[PATCH v4 00/20] gpio: cdev: add uAPI v2

[PATCH v4 00/20] gpio: cdev: add uAPI v2

[Kent Gibson]

This patchset defines and implements adds a new version of the
GPIO CDEV uAPI to address existing 32/64-bit alignment issues, add
support for debounce, event sequence numbers, and allowing for requested
lines with different configurations.
It provides some future proofing by adding optional configuration fields
and padding reserved for future use.

The series can be partitioned into two sets; the first eleven
contain the v2 uAPI implementation, and the final seven port
the GPIO tools to the v2 uAPI and extend them to use new uAPI features.

The more complicated patches include their own commentary where
appropriate.

Cheers,
Kent.

Changes for v4:
 - bitmap width clarification in gpiod.h (patch 04)
 - fix info offset initialisation bug (patch 08 and inserting patch 01)
 - replace strncpy with strscpy to remove compiler warnings
   (patch 08 and inserting patch 02)
 - fix mask handling in line_get_values (patch 07)

Changes for v3:
 - disabling the character device from the build requires EXPERT
 - uAPI revisions (see patch 02)
 - replace padding_not_zeroed with calls to memchr_inv
 - don't use bitops on 64-bit flags as that doesn't work on BE-32
 - accept first attribute matching a line in gpio_v2_line_config.attrs
   rather than the last
 - rework lsgpio port to uAPI v2 as flags reverted to v1 like layout
   (since patch v2)
 - swapped patches 17 and 18 to apply debounce to multiple monitored
   lines

Changes for v2:
 - split out cleanup patches into a separate series.
 - split implementation patch into a patch for each ioctl or major feature.
 - split tool port patch into a patch per tool.
 - rework uAPI to allow requested lines with different configurations.


Kent Gibson (20):
  gpiolib: cdev: desc_to_lineinfo should set info offset
  gpiolib: cdev: replace strncpy with strscpy
  gpio: uapi: define GPIO_MAX_NAME_SIZE for array sizes
  gpio: uapi: define uAPI v2
  gpiolib: make cdev a build option
  gpiolib: add build option for CDEV v1 ABI
  gpiolib: cdev: support GPIO_V2_GET_LINE_IOCTL and
    GPIO_V2_LINE_GET_VALUES_IOCTL
  gpiolib: cdev: support GPIO_V2_GET_LINEINFO_IOCTL and
    GPIO_V2_GET_LINEINFO_WATCH_IOCTL
  gpiolib: cdev: support edge detection for uAPI v2
  gpiolib: cdev: support GPIO_V2_LINE_SET_CONFIG_IOCTL
  gpiolib: cdev: support GPIO_V2_LINE_SET_VALUES_IOCTL
  gpiolib: cdev: support setting debounce
  gpio: uapi: document uAPI v1 as deprecated
  tools: gpio: port lsgpio to v2 uAPI
  tools: gpio: port gpio-watch to v2 uAPI
  tools: gpio: rename nlines to num_lines
  tools: gpio: port gpio-hammer to v2 uAPI
  tools: gpio: port gpio-event-mon to v2 uAPI
  tools: gpio: add multi-line monitoring to gpio-event-mon
  tools: gpio: add debounce support to gpio-event-mon

 drivers/gpio/Kconfig        |   29 +-
 drivers/gpio/Makefile       |    2 +-
 drivers/gpio/gpiolib-cdev.c | 1354 +++++++++++++++++++++++++++++++++--
 drivers/gpio/gpiolib-cdev.h |   15 +
 drivers/gpio/gpiolib.c      |    2 +
 drivers/gpio/gpiolib.h      |    6 +
 include/uapi/linux/gpio.h   |  316 +++++++-
 tools/gpio/gpio-event-mon.c |  146 ++--
 tools/gpio/gpio-hammer.c    |   56 +-
 tools/gpio/gpio-utils.c     |  127 ++--
 tools/gpio/gpio-utils.h     |   50 +-
 tools/gpio/gpio-watch.c     |   16 +-
 tools/gpio/lsgpio.c         |   60 +-
 13 files changed, 1949 insertions(+), 230 deletions(-)


base-commit: 22cc422070d9a9a399f8a70b89f1b852945444cb
-- 
2.28.0

[PATCH v4 01/20] gpiolib: cdev: desc_to_lineinfo should set info offset

[Kent Gibson]

Set the value of the line info offset in desc_to_lineinfo, rather than
relying on it being passed in the info.  This makes the function behave
as you would expect from the name - it generates the line info
corresponding to a given GPIO desc.

Signed-off-by: Kent Gibson <warthog618@gmail.com>
---

There are some instances where this results in the offset being set when
it is already set in the info, but I think this is clearer especially
considering that, as part of the replacement of strncpy with strscpy and
to to ensure kernel stack cannot be leaked to userspace, the info is
zeroed in a subsequent patch.

 drivers/gpio/gpiolib-cdev.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/gpio/gpiolib-cdev.c b/drivers/gpio/gpiolib-cdev.c
index e6c9b78adfc2..e95e3eab9867 100644
--- a/drivers/gpio/gpiolib-cdev.c
+++ b/drivers/gpio/gpiolib-cdev.c
@@ -752,6 +752,7 @@ static void gpio_desc_to_lineinfo(struct gpio_desc *desc,
 	bool ok_for_pinctrl;
 	unsigned long flags;
 
+	info->line_offset = gpio_chip_hwgpio(desc);
 	/*
 	 * This function takes a mutex so we must check this before taking
 	 * the spinlock.
@@ -933,7 +934,6 @@ static int lineinfo_changed_notify(struct notifier_block *nb,
 		return NOTIFY_DONE;
 
 	memset(&chg, 0, sizeof(chg));
-	chg.info.line_offset = gpio_chip_hwgpio(desc);
 	chg.event_type = action;
 	chg.timestamp = ktime_get_ns();
 	gpio_desc_to_lineinfo(desc, &chg.info);
-- 
2.28.0

[PATCH v4 02/20] gpiolib: cdev: replace strncpy with strscpy

[Kent Gibson]

Replace usage of strncpy with strscpy to remove -Wstringop-truncation
warnings.

The structs being populated are zeroed, to prevent stack leakage as
they are returned to userspace, so strscpy performs the equivalent
function without the warnings.

Reported-by: kernel test robot <lkp@intel.com>
Signed-off-by: Kent Gibson <warthog618@gmail.com>
---

The memset in gpio_desc_to_lineinfo(), in conjunction with the strscpy,
is necessary as strncpy zeroed pads the remainder of the destination.
It is also guarantees that the info cannot contain kernel stack that could
get leaked to userspace.  This is useful here, but is even more important
for the v2 info that this function is changed to generate in a subsequent
patch as that struct contains padding and attribute arrays that need to be
initialised.

 drivers/gpio/gpiolib-cdev.c | 23 +++++++----------------
 1 file changed, 7 insertions(+), 16 deletions(-)

diff --git a/drivers/gpio/gpiolib-cdev.c b/drivers/gpio/gpiolib-cdev.c
index e95e3eab9867..8b012879fe3f 100644
--- a/drivers/gpio/gpiolib-cdev.c
+++ b/drivers/gpio/gpiolib-cdev.c
@@ -752,6 +752,7 @@ static void gpio_desc_to_lineinfo(struct gpio_desc *desc,
 	bool ok_for_pinctrl;
 	unsigned long flags;
 
+	memset(info, 0, sizeof(*info));
 	info->line_offset = gpio_chip_hwgpio(desc);
 	/*
 	 * This function takes a mutex so we must check this before taking
@@ -765,19 +766,11 @@ static void gpio_desc_to_lineinfo(struct gpio_desc *desc,
 
 	spin_lock_irqsave(&gpio_lock, flags);
 
-	if (desc->name) {
-		strncpy(info->name, desc->name, sizeof(info->name));
-		info->name[sizeof(info->name) - 1] = '\0';
-	} else {
-		info->name[0] = '\0';
-	}
+	if (desc->name)
+		strscpy(info->name, desc->name, sizeof(info->name));
 
-	if (desc->label) {
-		strncpy(info->consumer, desc->label, sizeof(info->consumer));
-		info->consumer[sizeof(info->consumer) - 1] = '\0';
-	} else {
-		info->consumer[0] = '\0';
-	}
+	if (desc->label)
+		strscpy(info->consumer, desc->label, sizeof(info->consumer));
 
 	/*
 	 * Userspace only need to know that the kernel is using this GPIO so
@@ -841,12 +834,10 @@ static long gpio_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
 
 		memset(&chipinfo, 0, sizeof(chipinfo));
 
-		strncpy(chipinfo.name, dev_name(&gdev->dev),
+		strscpy(chipinfo.name, dev_name(&gdev->dev),
 			sizeof(chipinfo.name));
-		chipinfo.name[sizeof(chipinfo.name)-1] = '\0';
-		strncpy(chipinfo.label, gdev->label,
+		strscpy(chipinfo.label, gdev->label,
 			sizeof(chipinfo.label));
-		chipinfo.label[sizeof(chipinfo.label)-1] = '\0';
 		chipinfo.lines = gdev->ngpio;
 		if (copy_to_user(ip, &chipinfo, sizeof(chipinfo)))
 			return -EFAULT;
-- 
2.28.0

[PATCH v4 03/20] gpio: uapi: define GPIO_MAX_NAME_SIZE for array sizes

[Kent Gibson]

Replace constant array sizes with a macro constant to clarify the source
of array sizes, provide a place to document any constraints on the size,
and to simplify array sizing in userspace if constructing structs
from their composite fields.

Signed-off-by: Kent Gibson <warthog618@gmail.com>
---
 include/uapi/linux/gpio.h | 17 +++++++++++------
 1 file changed, 11 insertions(+), 6 deletions(-)

diff --git a/include/uapi/linux/gpio.h b/include/uapi/linux/gpio.h
index 9c27cecf406f..285cc10355b2 100644
--- a/include/uapi/linux/gpio.h
+++ b/include/uapi/linux/gpio.h
@@ -14,6 +14,11 @@
 #include <linux/ioctl.h>
 #include <linux/types.h>
 
+/*
+ * The maximum size of name and label arrays.
+ */
+#define GPIO_MAX_NAME_SIZE 32
+
 /**
  * struct gpiochip_info - Information about a certain GPIO chip
  * @name: the Linux kernel name of this GPIO chip
@@ -22,8 +27,8 @@
  * @lines: number of GPIO lines on this chip
  */
 struct gpiochip_info {
-	char name[32];
-	char label[32];
+	char name[GPIO_MAX_NAME_SIZE];
+	char label[GPIO_MAX_NAME_SIZE];
 	__u32 lines;
 };
 
@@ -52,8 +57,8 @@ struct gpiochip_info {
 struct gpioline_info {
 	__u32 line_offset;
 	__u32 flags;
-	char name[32];
-	char consumer[32];
+	char name[GPIO_MAX_NAME_SIZE];
+	char consumer[GPIO_MAX_NAME_SIZE];
 };
 
 /* Maximum number of requested handles */
@@ -123,7 +128,7 @@ struct gpiohandle_request {
 	__u32 lineoffsets[GPIOHANDLES_MAX];
 	__u32 flags;
 	__u8 default_values[GPIOHANDLES_MAX];
-	char consumer_label[32];
+	char consumer_label[GPIO_MAX_NAME_SIZE];
 	__u32 lines;
 	int fd;
 };
@@ -182,7 +187,7 @@ struct gpioevent_request {
 	__u32 lineoffset;
 	__u32 handleflags;
 	__u32 eventflags;
-	char consumer_label[32];
+	char consumer_label[GPIO_MAX_NAME_SIZE];
 	int fd;
 };
 
-- 
2.28.0

[PATCH v4 04/20] gpio: uapi: define uAPI v2

[Kent Gibson]

Add a new version of the uAPI to address existing 32/64-bit alignment
issues, add support for debounce and event sequence numbers, allow
requested lines with different configurations, and provide some future
proofing by adding padding reserved for future use.

The alignment issue relates to the gpioevent_data, which packs to different
sizes on 32-bit and 64-bit platforms. That creates problems for 32-bit apps
running on 64-bit kernels.  uAPI v2 addresses that particular issue, and
the problem more generally, by adding pad fields that explicitly pad
structs out to 64-bit boundaries, so they will pack to the same size now,
and even if some of the reserved padding is used for __u64 fields in the
future.

The new structs have been analysed with pahole to ensure that they
are sized as expected and contain no implicit padding.

The lack of future proofing in v1 makes it impossible to, for example,
add the debounce feature that is included in v2.
The future proofing is addressed by providing configurable attributes in
line config and reserved padding in all structs for future features.
Specifically, the line request, config, info, info_changed and event
structs receive updated versions and new ioctls.

As the majority of the structs and ioctls were being replaced, it is
opportune to rework some of the other aspects of the uAPI:

v1 has three different flags fields, each with their own separate
bit definitions.  In v2 that is collapsed to one - gpio_v2_line_flag.

The handle and event requests are merged into a single request, the line
request, as the two requests were mostly the same other than the edge
detection provided by event requests.  As a byproduct, the v2 uAPI allows
for multiple lines producing edge events on the same line handle.
This is a new capability as v1 only supports a single line in an event
request.

As a consequence, there are now only two types of file handle to be
concerned with, the chip and the line, and it is clearer which ioctls
apply to which type of handle.

There is also some minor renaming of fields for consistency compared to
their v1 counterparts, e.g. offset rather than lineoffset or line_offset,
and consumer rather than consumer_label.

Additionally, v1 GPIOHANDLES_MAX becomes GPIO_V2_LINES_MAX in v2 for
clarity, and the gpiohandle_data __u8 array becomes a bitmap in
gpio_v2_line_values.

The v2 uAPI is mostly a reorganisation and extension of v1, so userspace
code, particularly libgpiod, should readily port to it.

Signed-off-by: Kent Gibson <warthog618@gmail.com>
---

Changes for v4:
 - clarify bitmap width in GPIO_V2_LINES_MAX description

Changes for v3:
 - relocated commentary into commit description
 - hard limit max requested lines to 64 so bitmaps always fit in a single
   u64.
 - prefix all v2 symbols with GPIO_V2
 - 64-bit flag values to ULL
 - use __aligned_u64 to ensure 64-bit fields are 64-bit aligned
 - support masked get values, as per set values.

Changes for v2:
 - lower case V1 and V2, except in capitalized names
 - hyphenate 32/64-bit
 - rename bitmap field to bits
 - drop PAD_SIZE consts in favour of hard coded numbers
 - sort includes
 - change config flags to __u64
 - increase padding of gpioline_event
 - relocate GPIOLINE_CHANGED enum into v2 section (is common with v1)
 - rework config to collapse direction, drive, bias and edge enums back
   into flags and add optional attributes that can be associated with a
   subset of the requested lines.

Changes for v1 (since the RFC):
 - document the constraints on array sizes to maintain 32/64 alignment
 - add sequence numbers to gpioline_event
 - use bitmap for values instead of array of __u8
 - gpioline_info_v2 contains gpioline_config instead of its composite fields
 - provide constants for all array sizes, especially padding
 - renamed "GPIOLINE_FLAG_V2_KERNEL" to "GPIOLINE_FLAG_V2_USED"
 - renamed "default_values" to "values"
 - made gpioline_direction zero based
 - document clock used in gpioline_event timestamp
 - add event_buffer_size to gpioline_request
 - rename debounce to debounce_period
 - rename lines to num_lines

 include/uapi/linux/gpio.h | 273 +++++++++++++++++++++++++++++++++++++-
 1 file changed, 266 insertions(+), 7 deletions(-)

diff --git a/include/uapi/linux/gpio.h b/include/uapi/linux/gpio.h
index 285cc10355b2..0eb1f53b47e0 100644
--- a/include/uapi/linux/gpio.h
+++ b/include/uapi/linux/gpio.h
@@ -16,6 +16,8 @@
 
 /*
  * The maximum size of name and label arrays.
+ *
+ * Must be a multiple of 8 to ensure 32/64-bit alignment of structs.
  */
 #define GPIO_MAX_NAME_SIZE 32
 
@@ -32,6 +34,248 @@ struct gpiochip_info {
 	__u32 lines;
 };
 
+/*
+ * Maximum number of requested lines.
+ *
+ * Must be no greater than 64, as bitmaps are restricted here to 64-bits
+ * for simplicity, and a multiple of 2 to ensure 32/64-bit alignment of
+ * structs.
+ */
+#define GPIO_V2_LINES_MAX 64
+
+/*
+ * The maximum number of configuration attributes associated with a line
+ * request.
+ */
+#define GPIO_V2_LINE_NUM_ATTRS_MAX 10
+
+/**
+ * enum gpio_v2_line_flag - &struct gpio_v2_line_attribute.flags values
+ */
+enum gpio_v2_line_flag {
+	GPIO_V2_LINE_FLAG_USED			= 1ULL << 0, /* line is not available for request */
+	GPIO_V2_LINE_FLAG_ACTIVE_LOW		= 1ULL << 1,
+	GPIO_V2_LINE_FLAG_INPUT			= 1ULL << 2,
+	GPIO_V2_LINE_FLAG_OUTPUT		= 1ULL << 3,
+	GPIO_V2_LINE_FLAG_EDGE_RISING		= 1ULL << 4,
+	GPIO_V2_LINE_FLAG_EDGE_FALLING		= 1ULL << 5,
+	GPIO_V2_LINE_FLAG_OPEN_DRAIN		= 1ULL << 6,
+	GPIO_V2_LINE_FLAG_OPEN_SOURCE		= 1ULL << 7,
+	GPIO_V2_LINE_FLAG_BIAS_PULL_UP		= 1ULL << 8,
+	GPIO_V2_LINE_FLAG_BIAS_PULL_DOWN	= 1ULL << 9,
+	GPIO_V2_LINE_FLAG_BIAS_DISABLED		= 1ULL << 10,
+};
+
+/**
+ * struct gpio_v2_line_values - Values of GPIO lines
+ * @mask: a bitmap identifying the lines to get or set, with each bit
+ * number corresponding to the index into &struct
+ * gpio_v2_line_request.offsets.
+ * @bits: a bitmap containing the value of the lines, set to 1 for active
+ * and 0 for inactive.  Note that this is the logical value, which will be
+ * the opposite of the physical value if the line is configured as active
+ * low.
+ */
+struct gpio_v2_line_values {
+	__aligned_u64 mask;
+	__aligned_u64 bits;
+};
+
+/**
+ * enum gpio_v2_line_attr_id - &struct gpio_v2_line_attribute.id values
+ */
+enum gpio_v2_line_attr_id {
+	GPIO_V2_LINE_ATTR_ID_FLAGS		= 1,
+	GPIO_V2_LINE_ATTR_ID_OUTPUT_VALUES	= 2,
+	GPIO_V2_LINE_ATTR_ID_DEBOUNCE		= 3,
+};
+
+/**
+ * struct gpio_v2_line_attribute - a configurable attribute of a line
+ * @id: attribute identifier with value from &enum gpio_v2_line_attr_id
+ * @padding: reserved for future use and must be zero filled
+ * @flags: if id is GPIO_V2_LINE_ATTR_ID_FLAGS, the flags for the GPIO
+ * line, with values from enum gpio_v2_line_flag, such as
+ * GPIO_V2_LINE_FLAG_ACTIVE_LOW, GPIO_V2_LINE_FLAG_OUTPUT etc, OR:ed
+ * together.  This overrides the default flags contained in the &struct
+ * gpio_v2_line_config for the associated line.
+ * @values: if id is GPIO_V2_LINE_ATTR_ID_OUTPUT_VALUES, a bitmap
+ * containing the values to which the lines will be set, with each bit
+ * number corresponding to the index into &struct
+ * gpio_v2_line_request.offsets.
+ * @debounce_period: if id is GPIO_V2_LINE_ATTR_ID_DEBOUNCE, the desired
+ * debounce period, in microseconds
+ */
+struct gpio_v2_line_attribute {
+	__u32 id;
+	__u32 padding;
+	union {
+		__aligned_u64 flags;
+		__aligned_u64 values;
+		__u32 debounce_period;
+	};
+};
+
+/**
+ * struct gpio_v2_line_config_attribute - a configuration attribute
+ * associated with one or more of the requested lines.
+ * @mask: a bitmap identifying the lines to which the attribute applies,
+ * with each bit number corresponding to the index into &struct
+ * gpio_v2_line_request.offsets.
+ * @attr: the configurable attribute
+ */
+struct gpio_v2_line_config_attribute {
+	__aligned_u64 mask;
+	struct gpio_v2_line_attribute attr;
+};
+
+/**
+ * struct gpio_v2_line_config - Configuration for GPIO lines
+ * @flags: flags for the GPIO lines, with values from enum
+ * gpio_v2_line_flag, such as GPIO_V2_LINE_FLAG_ACTIVE_LOW,
+ * GPIO_V2_LINE_FLAG_OUTPUT etc, OR:ed together.  This is the default for
+ * all requested lines but may be overridden for particular lines using
+ * attrs.
+ * @num_attrs: the number of attributes in attrs
+ * @padding: reserved for future use and must be zero filled
+ * @attrs: the configuration attributes associated with the requested
+ * lines.  Any attribute should only be associated with a particular line
+ * once.  If an attribute is associated with a line multiple times then the
+ * first occurrence (i.e. lowest index) has precedence.
+ */
+struct gpio_v2_line_config {
+	__aligned_u64 flags;
+	__u32 num_attrs;
+	/*
+	 * Pad to fill implicit padding and provide space for future use.
+	 */
+	__u32 padding[5];
+	struct gpio_v2_line_config_attribute attrs[GPIO_V2_LINE_NUM_ATTRS_MAX];
+};
+
+/**
+ * struct gpio_v2_line_request - Information about a request for GPIO lines
+ * @offsets: an array of desired lines, specified by offset index for the
+ * associated GPIO device
+ * @consumer: a desired consumer label for the selected GPIO lines such as
+ * "my-bitbanged-relay"
+ * @config: requested configuration for the lines.
+ * @num_lines: number of lines requested in this request, i.e. the number
+ * of valid fields in the GPIO_V2_LINES_MAX sized arrays, set to 1 to
+ * request a single line
+ * @event_buffer_size: a suggested minimum number of line events that the
+ * kernel should buffer.  This is only relevant if edge detection is
+ * enabled in the configuration. Note that this is only a suggested value
+ * and the kernel may allocate a larger buffer or cap the size of the
+ * buffer. If this field is zero then the buffer size defaults to a minimum
+ * of num_lines*16.
+ * @padding: reserved for future use and must be zero filled
+ * @fd: if successful this field will contain a valid anonymous file handle
+ * after a GPIO_GET_LINE_IOCTL operation, zero or negative value means
+ * error
+ */
+struct gpio_v2_line_request {
+	__u32 offsets[GPIO_V2_LINES_MAX];
+	char consumer[GPIO_MAX_NAME_SIZE];
+	struct gpio_v2_line_config config;
+	__u32 num_lines;
+	__u32 event_buffer_size;
+	/*
+	 * Pad struct to 64-bit boundary and provide space for future use.
+	 */
+	__u32 padding[5];
+	__s32 fd;
+};
+
+/**
+ * struct gpio_v2_line_info - Information about a certain GPIO line
+ * @name: the name of this GPIO line, such as the output pin of the line on
+ * the chip, a rail or a pin header name on a board, as specified by the
+ * gpio chip, may be empty
+ * @consumer: a functional name for the consumer of this GPIO line as set
+ * by whatever is using it, will be empty if there is no current user but
+ * may also be empty if the consumer doesn't set this up
+ * @flags: flags for the GPIO line, such as GPIO_V2_LINE_FLAG_ACTIVE_LOW,
+ * GPIO_V2_LINE_FLAG_OUTPUT etc, OR:ed together
+ * @offset: the local offset on this GPIO device, fill this in when
+ * requesting the line information from the kernel
+ * @num_attrs: the number of attributes in attrs
+ * @attrs: the configuration attributes associated with the line.
+ * @padding: reserved for future use
+ */
+struct gpio_v2_line_info {
+	char name[GPIO_MAX_NAME_SIZE];
+	char consumer[GPIO_MAX_NAME_SIZE];
+	__u32 offset;
+	__u32 num_attrs;
+	__aligned_u64 flags;
+	struct gpio_v2_line_attribute attrs[GPIO_V2_LINE_NUM_ATTRS_MAX];
+	/*
+	 * Pad struct to 64-bit boundary and provide space for future use.
+	 */
+	__u32 padding[4];
+};
+
+enum gpio_v2_line_changed_type {
+	GPIO_V2_LINE_CHANGED_REQUESTED	= 1,
+	GPIO_V2_LINE_CHANGED_RELEASED	= 2,
+	GPIO_V2_LINE_CHANGED_CONFIG	= 3,
+};
+
+/**
+ * struct gpio_v2_line_info_changed - Information about a change in status
+ * of a GPIO line
+ * @info: updated line information
+ * @timestamp: estimate of time of status change occurrence, in nanoseconds
+ * @event_type: the type of change with a value from enum
+ * gpio_v2_line_changed_type
+ * @padding: reserved for future use
+ */
+struct gpio_v2_line_info_changed {
+	struct gpio_v2_line_info info;
+	__aligned_u64 timestamp;
+	__u32 event_type;
+	/*
+	 * Pad struct to 64-bit boundary and provide space for future use.
+	 */
+	__u32 padding[5];
+};
+
+enum gpio_v2_line_event_id {
+	GPIO_V2_LINE_EVENT_RISING_EDGE	= 1,
+	GPIO_V2_LINE_EVENT_FALLING_EDGE	= 2,
+};
+
+/**
+ * struct gpio_v2_line_event - The actual event being pushed to userspace
+ * @timestamp: best estimate of time of event occurrence, in nanoseconds.
+ * The timestamp is read from CLOCK_MONOTONIC and is intended to allow the
+ * accurate measurement of the time between events.  It does not provide
+ * the wall-clock time.
+ * @id: event identifier with value from enum gpio_v2_line_event_id
+ * @offset: the offset of the line that triggered the event
+ * @seqno: the sequence number for this event in the sequence of events for
+ * all the lines in this line request
+ * @line_seqno: the sequence number for this event in the sequence of
+ * events on this particular line
+ * @padding: reserved for future use
+ */
+struct gpio_v2_line_event {
+	__aligned_u64 timestamp;
+	__u32 id;
+	__u32 offset;
+	__u32 seqno;
+	__u32 line_seqno;
+	/*
+	 * Pad struct to 64-bit boundary and provide space for future use.
+	 */
+	__u32 padding[6];
+};
+
+/*
+ *  ABI v1
+ */
+
 /* Informational flags */
 #define GPIOLINE_FLAG_KERNEL		(1UL << 0) /* Line used by the kernel */
 #define GPIOLINE_FLAG_IS_OUT		(1UL << 1)
@@ -149,8 +393,6 @@ struct gpiohandle_config {
 	__u32 padding[4]; /* padding for future use */
 };
 
-#define GPIOHANDLE_SET_CONFIG_IOCTL _IOWR(0xB4, 0x0a, struct gpiohandle_config)
-
 /**
  * struct gpiohandle_data - Information of values on a GPIO handle
  * @values: when getting the state of lines this contains the current
@@ -161,9 +403,6 @@ struct gpiohandle_data {
 	__u8 values[GPIOHANDLES_MAX];
 };
 
-#define GPIOHANDLE_GET_LINE_VALUES_IOCTL _IOWR(0xB4, 0x08, struct gpiohandle_data)
-#define GPIOHANDLE_SET_LINE_VALUES_IOCTL _IOWR(0xB4, 0x09, struct gpiohandle_data)
-
 /* Eventrequest flags */
 #define GPIOEVENT_REQUEST_RISING_EDGE	(1UL << 0)
 #define GPIOEVENT_REQUEST_FALLING_EDGE	(1UL << 1)
@@ -207,11 +446,31 @@ struct gpioevent_data {
 	__u32 id;
 };
 
+/*
+ * v1 and v2 ioctl()s
+ */
 #define GPIO_GET_CHIPINFO_IOCTL _IOR(0xB4, 0x01, struct gpiochip_info)
+#define GPIO_GET_LINEINFO_UNWATCH_IOCTL _IOWR(0xB4, 0x0C, __u32)
+
+/*
+ * v2 ioctl()s
+ */
+#define GPIO_V2_GET_LINEINFO_IOCTL _IOWR(0xB4, 0x05, struct gpio_v2_line_info)
+#define GPIO_V2_GET_LINEINFO_WATCH_IOCTL _IOWR(0xB4, 0x06, struct gpio_v2_line_info)
+#define GPIO_V2_GET_LINE_IOCTL _IOWR(0xB4, 0x07, struct gpio_v2_line_request)
+#define GPIO_V2_LINE_SET_CONFIG_IOCTL _IOWR(0xB4, 0x0D, struct gpio_v2_line_config)
+#define GPIO_V2_LINE_GET_VALUES_IOCTL _IOWR(0xB4, 0x0E, struct gpio_v2_line_values)
+#define GPIO_V2_LINE_SET_VALUES_IOCTL _IOWR(0xB4, 0x0F, struct gpio_v2_line_values)
+
+/*
+ * v1 ioctl()s
+ */
 #define GPIO_GET_LINEINFO_IOCTL _IOWR(0xB4, 0x02, struct gpioline_info)
-#define GPIO_GET_LINEINFO_WATCH_IOCTL _IOWR(0xB4, 0x0b, struct gpioline_info)
-#define GPIO_GET_LINEINFO_UNWATCH_IOCTL _IOWR(0xB4, 0x0c, __u32)
 #define GPIO_GET_LINEHANDLE_IOCTL _IOWR(0xB4, 0x03, struct gpiohandle_request)
 #define GPIO_GET_LINEEVENT_IOCTL _IOWR(0xB4, 0x04, struct gpioevent_request)
+#define GPIOHANDLE_GET_LINE_VALUES_IOCTL _IOWR(0xB4, 0x08, struct gpiohandle_data)
+#define GPIOHANDLE_SET_LINE_VALUES_IOCTL _IOWR(0xB4, 0x09, struct gpiohandle_data)
+#define GPIOHANDLE_SET_CONFIG_IOCTL _IOWR(0xB4, 0x0A, struct gpiohandle_config)
+#define GPIO_GET_LINEINFO_WATCH_IOCTL _IOWR(0xB4, 0x0B, struct gpioline_info)
 
 #endif /* _UAPI_GPIO_H_ */
-- 
2.28.0

[PATCH v4 05/20] gpiolib: make cdev a build option

[Kent Gibson]

Make the gpiolib-cdev module a build option.  This allows the CDEV
interface to be removed from the kernel to reduce kernel size in
applications where is it not required, and provides the parent for
other other CDEV interface specific build options to follow.

Suggested-by: Bartosz Golaszewski <bgolaszewski@baylibre.com>
Signed-off-by: Kent Gibson <warthog618@gmail.com>
---
 drivers/gpio/Kconfig        | 17 +++++++++++++++--
 drivers/gpio/Makefile       |  2 +-
 drivers/gpio/gpiolib-cdev.h | 15 +++++++++++++++
 3 files changed, 31 insertions(+), 3 deletions(-)

diff --git a/drivers/gpio/Kconfig b/drivers/gpio/Kconfig
index 8030fd91a3cc..8e409b9c33dc 100644
--- a/drivers/gpio/Kconfig
+++ b/drivers/gpio/Kconfig
@@ -66,8 +66,21 @@ config GPIO_SYSFS
 
 	  This ABI is deprecated. If you want to use GPIO from userspace,
 	  use the character device /dev/gpiochipN with the appropriate
-	  ioctl() operations instead. The character device is always
-	  available.
+	  ioctl() operations instead.
+
+config GPIO_CDEV
+	bool
+	prompt "Character device (/dev/gpiochipN) support" if EXPERT
+	default y
+	help
+	  Say Y here to add the character device /dev/gpiochipN interface
+	  for GPIOs. The character device allows userspace to control GPIOs
+	  using ioctl() operations.
+
+	  Only say N if you are sure that the GPIO character device is not
+	  required.
+
+	  If unsure, say Y.
 
 config GPIO_GENERIC
 	depends on HAS_IOMEM # Only for IOMEM drivers
diff --git a/drivers/gpio/Makefile b/drivers/gpio/Makefile
index 4f9abff4f2dc..7c24c8d77068 100644
--- a/drivers/gpio/Makefile
+++ b/drivers/gpio/Makefile
@@ -7,8 +7,8 @@ obj-$(CONFIG_GPIOLIB)		+= gpiolib.o
 obj-$(CONFIG_GPIOLIB)		+= gpiolib-devres.o
 obj-$(CONFIG_GPIOLIB)		+= gpiolib-legacy.o
 obj-$(CONFIG_GPIOLIB)		+= gpiolib-devprop.o
-obj-$(CONFIG_GPIOLIB)		+= gpiolib-cdev.o
 obj-$(CONFIG_OF_GPIO)		+= gpiolib-of.o
+obj-$(CONFIG_GPIO_CDEV)		+= gpiolib-cdev.o
 obj-$(CONFIG_GPIO_SYSFS)	+= gpiolib-sysfs.o
 obj-$(CONFIG_GPIO_ACPI)		+= gpiolib-acpi.o
 
diff --git a/drivers/gpio/gpiolib-cdev.h b/drivers/gpio/gpiolib-cdev.h
index 973578e7ad10..19a4e3d57120 100644
--- a/drivers/gpio/gpiolib-cdev.h
+++ b/drivers/gpio/gpiolib-cdev.h
@@ -5,7 +5,22 @@
 
 #include <linux/device.h>
 
+#ifdef CONFIG_GPIO_CDEV
+
 int gpiolib_cdev_register(struct gpio_device *gdev, dev_t devt);
 void gpiolib_cdev_unregister(struct gpio_device *gdev);
 
+#else
+
+static inline int gpiolib_cdev_register(struct gpio_device *gdev, dev_t devt)
+{
+	return 0;
+}
+
+static inline void gpiolib_cdev_unregister(struct gpio_device *gdev)
+{
+}
+
+#endif /* CONFIG_GPIO_CDEV */
+
 #endif /* GPIOLIB_CDEV_H */
-- 
2.28.0

[PATCH v4 06/20] gpiolib: add build option for CDEV v1 ABI

[Kent Gibson]

Add a build option to allow the removal of the CDEV v1 ABI.

Suggested-by: Bartosz Golaszewski <bgolaszewski@baylibre.com>
Signed-off-by: Kent Gibson <warthog618@gmail.com>
---

This patch is before the v2 implementation, and is non-functional until
that patch, as some parts of that patch would be written slightly
differently if removing v1 was not considered.
Adding this patch after that would necessitate revisiting the v2 changes,
so this ordering results in two simpler patches.

 drivers/gpio/Kconfig | 12 ++++++++++++
 1 file changed, 12 insertions(+)

diff --git a/drivers/gpio/Kconfig b/drivers/gpio/Kconfig
index 8e409b9c33dc..0c62e35cf3a6 100644
--- a/drivers/gpio/Kconfig
+++ b/drivers/gpio/Kconfig
@@ -82,6 +82,18 @@ config GPIO_CDEV
 
 	  If unsure, say Y.
 
+config GPIO_CDEV_V1
+	bool "Support GPIO ABI Version 1"
+	default y
+	depends on GPIO_CDEV
+	help
+	  Say Y here to support version 1 of the GPIO CDEV ABI.
+
+	  This ABI version is deprecated and will be removed in the future.
+	  Please use the latest ABI for new developments.
+
+	  If unsure, say Y.
+
 config GPIO_GENERIC
 	depends on HAS_IOMEM # Only for IOMEM drivers
 	tristate
-- 
2.28.0

[PATCH v4 07/20] gpiolib: cdev: support GPIO_V2_GET_LINE_IOCTL and GPIO_V2_LINE_GET_VALUES_IOCTL

[Kent Gibson]

Add support for requesting lines using the GPIO_V2_GET_LINE_IOCTL, and
returning their current values using GPIO_V2_LINE_GET_VALUES_IOCTL.

Signed-off-by: Kent Gibson <warthog618@gmail.com>
---

The struct line implementation is based on the v1 struct linehandle
implementation.

The line_ioctl() is a simple wrapper around line_get_values() here, but
will be extended with other ioctls in subsequent patches.

Changes for v4:
 - fix handling of mask in line_get_values

 drivers/gpio/gpiolib-cdev.c | 413 ++++++++++++++++++++++++++++++++++++
 1 file changed, 413 insertions(+)

diff --git a/drivers/gpio/gpiolib-cdev.c b/drivers/gpio/gpiolib-cdev.c
index 8b012879fe3f..8671e04ff989 100644
--- a/drivers/gpio/gpiolib-cdev.c
+++ b/drivers/gpio/gpiolib-cdev.c
@@ -1,7 +1,9 @@
 // SPDX-License-Identifier: GPL-2.0
 
 #include <linux/anon_inodes.h>
+#include <linux/atomic.h>
 #include <linux/bitmap.h>
+#include <linux/build_bug.h>
 #include <linux/cdev.h>
 #include <linux/compat.h>
 #include <linux/device.h>
@@ -34,6 +36,7 @@
  * GPIO line handle management
  */
 
+#ifdef CONFIG_GPIO_CDEV_V1
 /**
  * struct linehandle_state - contains the state of a userspace handle
  * @gdev: the GPIO device the handle pertains to
@@ -376,6 +379,390 @@ static int linehandle_create(struct gpio_device *gdev, void __user *ip)
 	linehandle_free(lh);
 	return ret;
 }
+#endif /* CONFIG_GPIO_CDEV_V1 */
+
+/**
+ * struct line - contains the state of a userspace line request
+ * @gdev: the GPIO device the line request pertains to
+ * @label: consumer label used to tag descriptors
+ * @num_descs: the number of descriptors held in the descs array
+ * @descs: the GPIO descriptors held by this line request, with @num_descs
+ * elements.
+ */
+struct line {
+	struct gpio_device *gdev;
+	const char *label;
+	u32 num_descs;
+	struct gpio_desc *descs[];
+};
+
+#define GPIO_V2_LINE_BIAS_FLAGS \
+	(GPIO_V2_LINE_FLAG_BIAS_PULL_UP | \
+	 GPIO_V2_LINE_FLAG_BIAS_PULL_DOWN | \
+	 GPIO_V2_LINE_FLAG_BIAS_DISABLED)
+
+#define GPIO_V2_LINE_DIRECTION_FLAGS \
+	(GPIO_V2_LINE_FLAG_INPUT | \
+	 GPIO_V2_LINE_FLAG_OUTPUT)
+
+#define GPIO_V2_LINE_DRIVE_FLAGS \
+	(GPIO_V2_LINE_FLAG_OPEN_DRAIN | \
+	 GPIO_V2_LINE_FLAG_OPEN_SOURCE)
+
+#define GPIO_V2_LINE_VALID_FLAGS \
+	(GPIO_V2_LINE_FLAG_ACTIVE_LOW | \
+	 GPIO_V2_LINE_DIRECTION_FLAGS | \
+	 GPIO_V2_LINE_DRIVE_FLAGS | \
+	 GPIO_V2_LINE_BIAS_FLAGS)
+
+static u64 gpio_v2_line_config_flags(struct gpio_v2_line_config *lc,
+				     int line_idx)
+{
+	int i;
+	u64 mask = BIT_ULL(line_idx);
+
+	for (i = 0; i < lc->num_attrs; i++) {
+		if ((lc->attrs[i].attr.id == GPIO_V2_LINE_ATTR_ID_FLAGS) &&
+		    (lc->attrs[i].mask & mask))
+			return lc->attrs[i].attr.flags;
+	}
+	return lc->flags;
+}
+
+static int gpio_v2_line_config_output_value(struct gpio_v2_line_config *lc,
+					    int line_idx)
+{
+	int i;
+	u64 mask = BIT_ULL(line_idx);
+
+	for (i = 0; i < lc->num_attrs; i++) {
+		if ((lc->attrs[i].attr.id == GPIO_V2_LINE_ATTR_ID_OUTPUT_VALUES) &&
+		    (lc->attrs[i].mask & mask))
+			return !!(lc->attrs[i].attr.values & mask);
+	}
+	return 0;
+}
+
+static int gpio_v2_line_flags_validate(u64 flags)
+{
+	/* Return an error if an unknown flag is set */
+	if (flags & ~GPIO_V2_LINE_VALID_FLAGS)
+		return -EINVAL;
+
+	/*
+	 * Do not allow both INPUT & OUTPUT flags to be set as they are
+	 * contradictory.
+	 */
+	if ((flags & GPIO_V2_LINE_FLAG_INPUT) &&
+	    (flags & GPIO_V2_LINE_FLAG_OUTPUT))
+		return -EINVAL;
+
+	/*
+	 * Do not allow OPEN_SOURCE & OPEN_DRAIN flags in a single request. If
+	 * the hardware actually supports enabling both at the same time the
+	 * electrical result would be disastrous.
+	 */
+	if ((flags & GPIO_V2_LINE_FLAG_OPEN_DRAIN) &&
+	    (flags & GPIO_V2_LINE_FLAG_OPEN_SOURCE))
+		return -EINVAL;
+
+	/* Drive requires explicit output direction. */
+	if ((flags & GPIO_V2_LINE_DRIVE_FLAGS) &&
+	    !(flags & GPIO_V2_LINE_FLAG_OUTPUT))
+		return -EINVAL;
+
+	/* Bias requies explicit direction. */
+	if ((flags & GPIO_V2_LINE_BIAS_FLAGS) &&
+	    !(flags & GPIO_V2_LINE_DIRECTION_FLAGS))
+		return -EINVAL;
+
+	/* Only one bias flag can be set. */
+	if (((flags & GPIO_V2_LINE_FLAG_BIAS_DISABLED) &&
+	     (flags & (GPIO_V2_LINE_FLAG_BIAS_PULL_DOWN |
+		       GPIO_V2_LINE_FLAG_BIAS_PULL_UP))) ||
+	    ((flags & GPIO_V2_LINE_FLAG_BIAS_PULL_DOWN) &&
+	     (flags & GPIO_V2_LINE_FLAG_BIAS_PULL_UP)))
+		return -EINVAL;
+
+	return 0;
+}
+
+static int gpio_v2_line_config_validate(struct gpio_v2_line_config *lc,
+					int num_lines)
+{
+	int i, ret;
+	u64 flags;
+
+	if (lc->num_attrs > GPIO_V2_LINE_NUM_ATTRS_MAX)
+		return -EINVAL;
+
+	if (memchr_inv(lc->padding, 0, sizeof(lc->padding)))
+		return -EINVAL;
+
+	for (i = 0; i < num_lines; i++) {
+		flags = gpio_v2_line_config_flags(lc, i);
+		ret = gpio_v2_line_flags_validate(flags);
+		if (ret)
+			return ret;
+	}
+	return 0;
+}
+
+static void gpio_v2_line_config_flags_to_desc_flags(u64 flags,
+						    unsigned long *flagsp)
+{
+	assign_bit(FLAG_ACTIVE_LOW, flagsp,
+		   flags & GPIO_V2_LINE_FLAG_ACTIVE_LOW);
+	if (flags & GPIO_V2_LINE_FLAG_OUTPUT)
+		set_bit(FLAG_IS_OUT, flagsp);
+	else if (flags & GPIO_V2_LINE_FLAG_INPUT)
+		clear_bit(FLAG_IS_OUT, flagsp);
+	assign_bit(FLAG_OPEN_DRAIN, flagsp,
+		   flags & GPIO_V2_LINE_FLAG_OPEN_DRAIN);
+	assign_bit(FLAG_OPEN_SOURCE, flagsp,
+		   flags & GPIO_V2_LINE_FLAG_OPEN_SOURCE);
+	assign_bit(FLAG_PULL_UP, flagsp,
+		   flags & GPIO_V2_LINE_FLAG_BIAS_PULL_UP);
+	assign_bit(FLAG_PULL_DOWN, flagsp,
+		   flags & GPIO_V2_LINE_FLAG_BIAS_PULL_DOWN);
+	assign_bit(FLAG_BIAS_DISABLE, flagsp,
+		   flags & GPIO_V2_LINE_FLAG_BIAS_DISABLED);
+}
+
+static long line_get_values(struct line *line, void __user *ip)
+{
+	struct gpio_v2_line_values lv;
+	DECLARE_BITMAP(vals, GPIO_V2_LINES_MAX);
+	struct gpio_desc **descs;
+	int ret, i, didx, num_get = 0;
+
+	/* NOTE: It's ok to read values of output lines. */
+	if (copy_from_user(&lv, ip, sizeof(lv)))
+		return -EFAULT;
+
+	if (lv.mask == 0)
+		return -EINVAL;
+
+	for (i = 0; i < line->num_descs; i++)
+		if (lv.mask & BIT_ULL(i))
+			num_get++;
+	if (num_get == line->num_descs)	{
+		descs = line->descs;
+	} else {
+		descs = kmalloc_array(num_get, sizeof(*descs), GFP_KERNEL);
+		for (didx = 0, i = 0; i < line->num_descs; i++) {
+			if (lv.mask & BIT_ULL(i)) {
+				descs[didx] = line->descs[i];
+				didx++;
+			}
+		}
+	}
+	ret = gpiod_get_array_value_complex(false,
+					    true,
+					    num_get,
+					    descs,
+					    NULL,
+					    vals);
+
+	if (descs != line->descs)
+		kfree(descs);
+	if (ret)
+		return ret;
+
+	lv.bits = 0;
+	for (didx = 0, i = 0; i < line->num_descs; i++) {
+		if (lv.mask & BIT_ULL(i)) {
+			if (test_bit(didx, vals))
+				lv.bits |= BIT_ULL(i);
+			didx++;
+		}
+	}
+
+	if (copy_to_user(ip, &lv, sizeof(lv)))
+		return -EFAULT;
+
+	return 0;
+}
+
+static long line_ioctl(struct file *file, unsigned int cmd,
+		       unsigned long arg)
+{
+	struct line *line = file->private_data;
+	void __user *ip = (void __user *)arg;
+
+	if (cmd == GPIO_V2_LINE_GET_VALUES_IOCTL)
+		return line_get_values(line, ip);
+
+	return -EINVAL;
+}
+
+#ifdef CONFIG_COMPAT
+static long line_ioctl_compat(struct file *file, unsigned int cmd,
+			      unsigned long arg)
+{
+	return line_ioctl(file, cmd, (unsigned long)compat_ptr(arg));
+}
+#endif
+
+static void line_free(struct line *line)
+{
+	int i;
+
+	for (i = 0; i < line->num_descs; i++) {
+		if (line->descs[i])
+			gpiod_free(line->descs[i]);
+	}
+	kfree(line->label);
+	put_device(&line->gdev->dev);
+	kfree(line);
+}
+
+static int line_release(struct inode *inode, struct file *file)
+{
+	struct line *line = file->private_data;
+
+	line_free(line);
+	return 0;
+}
+
+static const struct file_operations line_fileops = {
+	.release = line_release,
+	.owner = THIS_MODULE,
+	.llseek = noop_llseek,
+	.unlocked_ioctl = line_ioctl,
+#ifdef CONFIG_COMPAT
+	.compat_ioctl = line_ioctl_compat,
+#endif
+};
+
+static int line_create(struct gpio_device *gdev, void __user *ip)
+{
+	struct gpio_v2_line_request lr;
+	struct line *line;
+	struct file *file;
+	int fd, i, ret;
+	struct gpio_v2_line_config *lc;
+	unsigned long flags;
+
+	if (copy_from_user(&lr, ip, sizeof(lr)))
+		return -EFAULT;
+	if ((lr.num_lines == 0) || (lr.num_lines > GPIO_V2_LINES_MAX))
+		return -EINVAL;
+
+	if (memchr_inv(lr.padding, 0, sizeof(lr.padding)))
+		return -EINVAL;
+
+	lc = &lr.config;
+	ret = gpio_v2_line_config_validate(lc, lr.num_lines);
+	if (ret)
+		return ret;
+
+	line = kzalloc(struct_size(line, descs, lr.num_lines),
+		       GFP_KERNEL);
+	if (!line)
+		return -ENOMEM;
+
+	line->gdev = gdev;
+	get_device(&gdev->dev);
+
+	/* Make sure this is terminated */
+	lr.consumer[sizeof(lr.consumer)-1] = '\0';
+	if (strlen(lr.consumer)) {
+		line->label = kstrdup(lr.consumer, GFP_KERNEL);
+		if (!line->label) {
+			ret = -ENOMEM;
+			goto out_free_line;
+		}
+	}
+
+	line->num_descs = lr.num_lines;
+
+	/* Request each GPIO */
+	for (i = 0; i < lr.num_lines; i++) {
+		u32 offset = lr.offsets[i];
+		struct gpio_desc *desc = gpiochip_get_desc(gdev->chip, offset);
+
+		if (IS_ERR(desc)) {
+			ret = PTR_ERR(desc);
+			goto out_free_line;
+		}
+
+		ret = gpiod_request(desc, line->label);
+		if (ret)
+			goto out_free_line;
+
+		line->descs[i] = desc;
+		flags = gpio_v2_line_config_flags(lc, i);
+		gpio_v2_line_config_flags_to_desc_flags(flags, &desc->flags);
+
+		ret = gpiod_set_transitory(desc, false);
+		if (ret < 0)
+			goto out_free_line;
+
+		/*
+		 * Lines have to be requested explicitly for input
+		 * or output, else the line will be treated "as is".
+		 */
+		if (flags & GPIO_V2_LINE_FLAG_OUTPUT) {
+			int val = gpio_v2_line_config_output_value(lc, i);
+
+			ret = gpiod_direction_output(desc, val);
+			if (ret)
+				goto out_free_line;
+		} else if (flags & GPIO_V2_LINE_FLAG_INPUT) {
+			ret = gpiod_direction_input(desc);
+			if (ret)
+				goto out_free_line;
+		}
+
+		blocking_notifier_call_chain(&desc->gdev->notifier,
+					     GPIOLINE_CHANGED_REQUESTED, desc);
+
+		dev_dbg(&gdev->dev, "registered chardev handle for line %d\n",
+			offset);
+	}
+
+	fd = get_unused_fd_flags(O_RDONLY | O_CLOEXEC);
+	if (fd < 0) {
+		ret = fd;
+		goto out_free_line;
+	}
+
+	file = anon_inode_getfile("gpio-line",
+				  &line_fileops,
+				  line,
+				  O_RDONLY | O_CLOEXEC);
+	if (IS_ERR(file)) {
+		ret = PTR_ERR(file);
+		goto out_put_unused_fd;
+	}
+
+	lr.fd = fd;
+	if (copy_to_user(ip, &lr, sizeof(lr))) {
+		/*
+		 * fput() will trigger the release() callback, so do not go onto
+		 * the regular error cleanup path here.
+		 */
+		fput(file);
+		put_unused_fd(fd);
+		return -EFAULT;
+	}
+
+	fd_install(fd, file);
+
+	dev_dbg(&gdev->dev, "registered chardev handle for %d lines\n",
+		line->num_descs);
+
+	return 0;
+
+out_put_unused_fd:
+	put_unused_fd(fd);
+out_free_line:
+	line_free(line);
+	return ret;
+}
+
+#ifdef CONFIG_GPIO_CDEV_V1
 
 /*
  * GPIO line event management
@@ -745,6 +1132,8 @@ static int lineevent_create(struct gpio_device *gdev, void __user *ip)
 	return ret;
 }
 
+#endif /* CONFIG_GPIO_CDEV_V1 */
+
 static void gpio_desc_to_lineinfo(struct gpio_desc *desc,
 				  struct gpioline_info *info)
 {
@@ -842,6 +1231,7 @@ static long gpio_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
 		if (copy_to_user(ip, &chipinfo, sizeof(chipinfo)))
 			return -EFAULT;
 		return 0;
+#ifdef CONFIG_GPIO_CDEV_V1
 	} else if (cmd == GPIO_GET_LINEINFO_IOCTL) {
 		struct gpioline_info lineinfo;
 
@@ -884,6 +1274,9 @@ static long gpio_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
 		}
 
 		return 0;
+#endif /* CONFIG_GPIO_CDEV_V1 */
+	} else if (cmd == GPIO_V2_GET_LINE_IOCTL) {
+		return line_create(gdev, ip);
 	} else if (cmd == GPIO_GET_LINEINFO_UNWATCH_IOCTL) {
 		if (copy_from_user(&offset, ip, sizeof(offset)))
 			return -EFAULT;
@@ -1109,4 +1502,24 @@ int gpiolib_cdev_register(struct gpio_device *gdev, dev_t devt)
 void gpiolib_cdev_unregister(struct gpio_device *gdev)
 {
 	cdev_device_del(&gdev->chrdev, &gdev->dev);
+
+	/*
+	 * array sizes must ensure 64-bit alignment and not create holes in
+	 * the struct packing.
+	 */
+	BUILD_BUG_ON(GPIO_V2_LINES_MAX % 2);
+	BUILD_BUG_ON(GPIO_MAX_NAME_SIZE % 8);
+
+	/*
+	 * check that uAPI structs are 64-bit aligned for 32/64-bit
+	 * compatibility
+	 */
+	BUILD_BUG_ON(sizeof(struct gpio_v2_line_attribute) % 8);
+	BUILD_BUG_ON(sizeof(struct gpio_v2_line_config_attribute) % 8);
+	BUILD_BUG_ON(sizeof(struct gpio_v2_line_config) % 8);
+	BUILD_BUG_ON(sizeof(struct gpio_v2_line_request) % 8);
+	BUILD_BUG_ON(sizeof(struct gpio_v2_line_info) % 8);
+	BUILD_BUG_ON(sizeof(struct gpio_v2_line_info_changed) % 8);
+	BUILD_BUG_ON(sizeof(struct gpio_v2_line_event) % 8);
+	BUILD_BUG_ON(sizeof(struct gpio_v2_line_values) % 8);
 }
-- 
2.28.0

[PATCH v4 08/20] gpiolib: cdev: support GPIO_V2_GET_LINEINFO_IOCTL and GPIO_V2_GET_LINEINFO_WATCH_IOCTL

[Kent Gibson]

Add support for GPIO_V2_GET_LINEINFO_IOCTL and
GPIO_V2_GET_LINEINFO_WATCH_IOCTL.

Signed-off-by: Kent Gibson <warthog618@gmail.com>
---

The core of this change is the event kfifo switching to contain
struct gpioline_info_changed_v2, instead of v1 as v2 is richer.

The two uAPI versions are mostly independent - other than where they both
provide line info changes via reads on the chip fd.  As the info change
structs differ between v1 and v2, the infowatch implementation tracks which
version of the infowatch ioctl, either GPIO_GET_LINEINFO_WATCH_IOCTL or
GPIO_V2_GET_LINEINFO_WATCH_IOCTL, initiates the initial watch and returns
the corresponding info change struct to the read.  The version supported
on that fd locks to that version on the first watch request, so subsequent
watches from that process must use the same uAPI version.

Changes for v4:
 - replace strncpy with memcpy in gpio_v2_line_info_to_v1

 drivers/gpio/gpiolib-cdev.c | 194 +++++++++++++++++++++++++++++++-----
 1 file changed, 167 insertions(+), 27 deletions(-)

diff --git a/drivers/gpio/gpiolib-cdev.c b/drivers/gpio/gpiolib-cdev.c
index 8671e04ff989..28273f3105d3 100644
--- a/drivers/gpio/gpiolib-cdev.c
+++ b/drivers/gpio/gpiolib-cdev.c
@@ -162,7 +162,8 @@ static long linehandle_set_config(struct linehandle_state *lh,
 		}
 
 		blocking_notifier_call_chain(&desc->gdev->notifier,
-					     GPIOLINE_CHANGED_CONFIG, desc);
+					     GPIO_V2_LINE_CHANGED_CONFIG,
+					     desc);
 	}
 	return 0;
 }
@@ -334,7 +335,7 @@ static int linehandle_create(struct gpio_device *gdev, void __user *ip)
 		}
 
 		blocking_notifier_call_chain(&desc->gdev->notifier,
-					     GPIOLINE_CHANGED_REQUESTED, desc);
+					     GPIO_V2_LINE_CHANGED_REQUESTED, desc);
 
 		dev_dbg(&gdev->dev, "registered chardev handle for line %d\n",
 			offset);
@@ -716,7 +717,7 @@ static int line_create(struct gpio_device *gdev, void __user *ip)
 		}
 
 		blocking_notifier_call_chain(&desc->gdev->notifier,
-					     GPIOLINE_CHANGED_REQUESTED, desc);
+					     GPIO_V2_LINE_CHANGED_REQUESTED, desc);
 
 		dev_dbg(&gdev->dev, "registered chardev handle for line %d\n",
 			offset);
@@ -1065,7 +1066,7 @@ static int lineevent_create(struct gpio_device *gdev, void __user *ip)
 		goto out_free_le;
 
 	blocking_notifier_call_chain(&desc->gdev->notifier,
-				     GPIOLINE_CHANGED_REQUESTED, desc);
+				     GPIO_V2_LINE_CHANGED_REQUESTED, desc);
 
 	irq = gpiod_to_irq(desc);
 	if (irq <= 0) {
@@ -1132,17 +1133,59 @@ static int lineevent_create(struct gpio_device *gdev, void __user *ip)
 	return ret;
 }
 
+static void gpio_v2_line_info_to_v1(struct gpio_v2_line_info *info_v2,
+				    struct gpioline_info *info_v1)
+{
+	int flagsv2 = info_v2->flags;
+
+	memcpy(info_v1->name, info_v2->name, sizeof(info_v1->name));
+	memcpy(info_v1->consumer, info_v2->consumer,
+	       sizeof(info_v1->consumer));
+	info_v1->line_offset = info_v2->offset;
+	info_v1->flags = 0;
+
+	if (flagsv2 & GPIO_V2_LINE_FLAG_USED)
+		info_v1->flags |= GPIOLINE_FLAG_KERNEL;
+
+	if (flagsv2 & GPIO_V2_LINE_FLAG_OUTPUT)
+		info_v1->flags |= GPIOLINE_FLAG_IS_OUT;
+
+	if (flagsv2 & GPIO_V2_LINE_FLAG_ACTIVE_LOW)
+		info_v1->flags |= GPIOLINE_FLAG_ACTIVE_LOW;
+
+	if (flagsv2 & GPIO_V2_LINE_FLAG_OPEN_DRAIN)
+		info_v1->flags |= GPIOLINE_FLAG_OPEN_DRAIN;
+	if (flagsv2 & GPIO_V2_LINE_FLAG_OPEN_SOURCE)
+		info_v1->flags |= GPIOLINE_FLAG_OPEN_SOURCE;
+
+	if (flagsv2 & GPIO_V2_LINE_FLAG_BIAS_PULL_UP)
+		info_v1->flags |= GPIOLINE_FLAG_BIAS_PULL_UP;
+	if (flagsv2 & GPIO_V2_LINE_FLAG_BIAS_PULL_DOWN)
+		info_v1->flags |= GPIOLINE_FLAG_BIAS_PULL_DOWN;
+	if (flagsv2 & GPIO_V2_LINE_FLAG_BIAS_DISABLED)
+		info_v1->flags |= GPIOLINE_FLAG_BIAS_DISABLE;
+}
+
+static void gpio_v2_line_info_changed_to_v1(
+		struct gpio_v2_line_info_changed *lic_v2,
+		struct gpioline_info_changed *lic_v1)
+{
+	gpio_v2_line_info_to_v1(&lic_v2->info, &lic_v1->info);
+	lic_v1->timestamp = lic_v2->timestamp;
+	lic_v1->event_type = lic_v2->event_type;
+}
+
 #endif /* CONFIG_GPIO_CDEV_V1 */
 
 static void gpio_desc_to_lineinfo(struct gpio_desc *desc,
-				  struct gpioline_info *info)
+				  struct gpio_v2_line_info *info)
 {
 	struct gpio_chip *gc = desc->gdev->chip;
 	bool ok_for_pinctrl;
 	unsigned long flags;
 
 	memset(info, 0, sizeof(*info));
-	info->line_offset = gpio_chip_hwgpio(desc);
+	info->offset = gpio_chip_hwgpio(desc);
 	/*
 	 * This function takes a mutex so we must check this before taking
 	 * the spinlock.
@@ -1151,7 +1194,7 @@ static void gpio_desc_to_lineinfo(struct gpio_desc *desc,
 	 * lock common to both frameworks?
 	 */
 	ok_for_pinctrl =
-		pinctrl_gpio_can_use_line(gc->base + info->line_offset);
+		pinctrl_gpio_can_use_line(gc->base + info->offset);
 
 	spin_lock_irqsave(&gpio_lock, flags);
 
@@ -1172,23 +1215,27 @@ static void gpio_desc_to_lineinfo(struct gpio_desc *desc,
 	    test_bit(FLAG_EXPORT, &desc->flags) ||
 	    test_bit(FLAG_SYSFS, &desc->flags) ||
 	    !ok_for_pinctrl)
-		info->flags |= GPIOLINE_FLAG_KERNEL;
+		info->flags |= GPIO_V2_LINE_FLAG_USED;
+
 	if (test_bit(FLAG_IS_OUT, &desc->flags))
-		info->flags |= GPIOLINE_FLAG_IS_OUT;
+		info->flags |= GPIO_V2_LINE_FLAG_OUTPUT;
+	else
+		info->flags |= GPIO_V2_LINE_FLAG_INPUT;
+
 	if (test_bit(FLAG_ACTIVE_LOW, &desc->flags))
-		info->flags |= GPIOLINE_FLAG_ACTIVE_LOW;
+		info->flags |= GPIO_V2_LINE_FLAG_ACTIVE_LOW;
+
 	if (test_bit(FLAG_OPEN_DRAIN, &desc->flags))
-		info->flags |= (GPIOLINE_FLAG_OPEN_DRAIN |
-				GPIOLINE_FLAG_IS_OUT);
+		info->flags |= GPIO_V2_LINE_FLAG_OPEN_DRAIN;
 	if (test_bit(FLAG_OPEN_SOURCE, &desc->flags))
-		info->flags |= (GPIOLINE_FLAG_OPEN_SOURCE |
-				GPIOLINE_FLAG_IS_OUT);
+		info->flags |= GPIO_V2_LINE_FLAG_OPEN_SOURCE;
+
 	if (test_bit(FLAG_BIAS_DISABLE, &desc->flags))
-		info->flags |= GPIOLINE_FLAG_BIAS_DISABLE;
+		info->flags |= GPIO_V2_LINE_FLAG_BIAS_DISABLED;
 	if (test_bit(FLAG_PULL_DOWN, &desc->flags))
-		info->flags |= GPIOLINE_FLAG_BIAS_PULL_DOWN;
+		info->flags |= GPIO_V2_LINE_FLAG_BIAS_PULL_DOWN;
 	if (test_bit(FLAG_PULL_UP, &desc->flags))
-		info->flags |= GPIOLINE_FLAG_BIAS_PULL_UP;
+		info->flags |= GPIO_V2_LINE_FLAG_BIAS_PULL_UP;
 
 	spin_unlock_irqrestore(&gpio_lock, flags);
 }
@@ -1196,11 +1243,65 @@ static void gpio_desc_to_lineinfo(struct gpio_desc *desc,
 struct gpio_chardev_data {
 	struct gpio_device *gdev;
 	wait_queue_head_t wait;
-	DECLARE_KFIFO(events, struct gpioline_info_changed, 32);
+	DECLARE_KFIFO(events, struct gpio_v2_line_info_changed, 32);
 	struct notifier_block lineinfo_changed_nb;
 	unsigned long *watched_lines;
+#ifdef CONFIG_GPIO_CDEV_V1
+	atomic_t watch_abi_version;
+#endif
 };
 
+#ifdef CONFIG_GPIO_CDEV_V1
+static int lineinfo_ensure_abi_version(struct gpio_chardev_data *cdata,
+				       unsigned int version)
+{
+	int abiv = atomic_read(&cdata->watch_abi_version);
+
+	if (abiv == 0) {
+		atomic_cmpxchg(&cdata->watch_abi_version, 0, version);
+		abiv = atomic_read(&cdata->watch_abi_version);
+	}
+	if (abiv != version)
+		return -EPERM;
+	return 0;
+}
+#endif
+
+static int lineinfo_get(struct gpio_chardev_data *cdev, void __user *ip,
+			unsigned int cmd)
+{
+	struct gpio_desc *desc;
+	struct gpio_v2_line_info lineinfo;
+
+	if (copy_from_user(&lineinfo, ip, sizeof(lineinfo)))
+		return -EFAULT;
+
+	if (memchr_inv(lineinfo.padding, 0, sizeof(lineinfo.padding)))
+		return -EINVAL;
+
+	desc = gpiochip_get_desc(cdev->gdev->chip, lineinfo.offset);
+	if (IS_ERR(desc))
+		return PTR_ERR(desc);
+
+	if (cmd == GPIO_V2_GET_LINEINFO_WATCH_IOCTL) {
+#ifdef CONFIG_GPIO_CDEV_V1
+		if (lineinfo_ensure_abi_version(cdev, 2))
+			return -EPERM;
+#endif
+		if (test_and_set_bit(lineinfo.offset, cdev->watched_lines))
+			return -EBUSY;
+	}
+	gpio_desc_to_lineinfo(desc, &lineinfo);
+
+	if (copy_to_user(ip, &lineinfo, sizeof(lineinfo))) {
+		if (cmd == GPIO_V2_GET_LINEINFO_WATCH_IOCTL)
+			clear_bit(lineinfo.offset, cdev->watched_lines);
+		return -EFAULT;
+	}
+
+	return 0;
+}
+
 /*
  * gpio_ioctl() - ioctl handler for the GPIO chardev
  */
@@ -1210,7 +1311,6 @@ static long gpio_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
 	struct gpio_device *gdev = cdev->gdev;
 	struct gpio_chip *gc = gdev->chip;
 	void __user *ip = (void __user *)arg;
-	struct gpio_desc *desc;
 	__u32 offset;
 
 	/* We fail any subsequent ioctl():s when the chip is gone */
@@ -1233,7 +1333,9 @@ static long gpio_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
 		return 0;
 #ifdef CONFIG_GPIO_CDEV_V1
 	} else if (cmd == GPIO_GET_LINEINFO_IOCTL) {
+		struct gpio_desc *desc;
 		struct gpioline_info lineinfo;
+		struct gpio_v2_line_info lineinfo_v2;
 
 		if (copy_from_user(&lineinfo, ip, sizeof(lineinfo)))
 			return -EFAULT;
@@ -1243,7 +1345,8 @@ static long gpio_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
 		if (IS_ERR(desc))
 			return PTR_ERR(desc);
 
-		gpio_desc_to_lineinfo(desc, &lineinfo);
+		gpio_desc_to_lineinfo(desc, &lineinfo_v2);
+		gpio_v2_line_info_to_v1(&lineinfo_v2, &lineinfo);
 
 		if (copy_to_user(ip, &lineinfo, sizeof(lineinfo)))
 			return -EFAULT;
@@ -1253,7 +1356,9 @@ static long gpio_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
 	} else if (cmd == GPIO_GET_LINEEVENT_IOCTL) {
 		return lineevent_create(gdev, ip);
 	} else if (cmd == GPIO_GET_LINEINFO_WATCH_IOCTL) {
+		struct gpio_desc *desc;
 		struct gpioline_info lineinfo;
+		struct gpio_v2_line_info lineinfo_v2;
 
 		if (copy_from_user(&lineinfo, ip, sizeof(lineinfo)))
 			return -EFAULT;
@@ -1263,10 +1368,14 @@ static long gpio_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
 		if (IS_ERR(desc))
 			return PTR_ERR(desc);
 
+		if (lineinfo_ensure_abi_version(cdev, 1))
+			return -EPERM;
+
 		if (test_and_set_bit(lineinfo.line_offset, cdev->watched_lines))
 			return -EBUSY;
 
-		gpio_desc_to_lineinfo(desc, &lineinfo);
+		gpio_desc_to_lineinfo(desc, &lineinfo_v2);
+		gpio_v2_line_info_to_v1(&lineinfo_v2, &lineinfo);
 
 		if (copy_to_user(ip, &lineinfo, sizeof(lineinfo))) {
 			clear_bit(lineinfo.line_offset, cdev->watched_lines);
@@ -1275,6 +1384,9 @@ static long gpio_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
 
 		return 0;
 #endif /* CONFIG_GPIO_CDEV_V1 */
+	} else if (cmd == GPIO_V2_GET_LINEINFO_IOCTL ||
+		   cmd == GPIO_V2_GET_LINEINFO_WATCH_IOCTL) {
+		return lineinfo_get(cdev, ip, cmd);
 	} else if (cmd == GPIO_V2_GET_LINE_IOCTL) {
 		return line_create(gdev, ip);
 	} else if (cmd == GPIO_GET_LINEINFO_UNWATCH_IOCTL) {
@@ -1310,7 +1422,7 @@ static int lineinfo_changed_notify(struct notifier_block *nb,
 				   unsigned long action, void *data)
 {
 	struct gpio_chardev_data *cdev = to_gpio_chardev_data(nb);
-	struct gpioline_info_changed chg;
+	struct gpio_v2_line_info_changed chg;
 	struct gpio_desc *desc = data;
 	int ret;
 
@@ -1350,12 +1462,16 @@ static ssize_t lineinfo_watch_read(struct file *file, char __user *buf,
 				   size_t count, loff_t *off)
 {
 	struct gpio_chardev_data *cdev = file->private_data;
-	struct gpioline_info_changed event;
+	struct gpio_v2_line_info_changed event;
 	ssize_t bytes_read = 0;
 	int ret;
+	size_t event_size;
 
-	if (count < sizeof(event))
+#ifndef CONFIG_GPIO_CDEV_V1
+	event_size = sizeof(struct gpio_v2_line_info_changed);
+	if (count < event_size)
 		return -EINVAL;
+#endif
 
 	do {
 		spin_lock(&cdev->wait.lock);
@@ -1377,7 +1493,17 @@ static ssize_t lineinfo_watch_read(struct file *file, char __user *buf,
 				return ret;
 			}
 		}
-
+#ifdef CONFIG_GPIO_CDEV_V1
+		/* must be after kfifo check so watch_abi_version is set */
+		if (atomic_read(&cdev->watch_abi_version) == 2)
+			event_size = sizeof(struct gpio_v2_line_info_changed);
+		else
+			event_size = sizeof(struct gpioline_info_changed);
+		if (count < event_size) {
+			spin_unlock(&cdev->wait.lock);
+			return -EINVAL;
+		}
+#endif
 		ret = kfifo_out(&cdev->events, &event, 1);
 		spin_unlock(&cdev->wait.lock);
 		if (ret != 1) {
@@ -1386,9 +1512,23 @@ static ssize_t lineinfo_watch_read(struct file *file, char __user *buf,
 			/* We should never get here. See lineevent_read(). */
 		}
 
-		if (copy_to_user(buf + bytes_read, &event, sizeof(event)))
+#ifdef CONFIG_GPIO_CDEV_V1
+		if (event_size == sizeof(struct gpio_v2_line_info_changed)) {
+			if (copy_to_user(buf + bytes_read, &event, event_size))
+				return -EFAULT;
+		} else {
+			struct gpioline_info_changed event_v1;
+
+			gpio_v2_line_info_changed_to_v1(&event, &event_v1);
+			if (copy_to_user(buf + bytes_read, &event_v1,
+					 event_size))
+				return -EFAULT;
+		}
+#else
+		if (copy_to_user(buf + bytes_read, &event, event_size))
 			return -EFAULT;
-		bytes_read += sizeof(event);
+#endif
+		bytes_read += event_size;
 	} while (count >= bytes_read + sizeof(event));
 
 	return bytes_read;
-- 
2.28.0

[PATCH v4 09/20] gpiolib: cdev: support edge detection for uAPI v2

[Kent Gibson]

Add support for edge detection to lines requested using
GPIO_V2_GET_LINE_IOCTL.

Signed-off-by: Kent Gibson <warthog618@gmail.com>
---

The edge_detector implementation is based on the v1 lineevent implementation.

 drivers/gpio/gpiolib-cdev.c | 316 +++++++++++++++++++++++++++++++++++-
 drivers/gpio/gpiolib.c      |   2 +
 drivers/gpio/gpiolib.h      |   2 +
 3 files changed, 319 insertions(+), 1 deletion(-)

diff --git a/drivers/gpio/gpiolib-cdev.c b/drivers/gpio/gpiolib-cdev.c
index 28273f3105d3..1d42a01f5414 100644
--- a/drivers/gpio/gpiolib-cdev.c
+++ b/drivers/gpio/gpiolib-cdev.c
@@ -382,11 +382,43 @@ static int linehandle_create(struct gpio_device *gdev, void __user *ip)
 }
 #endif /* CONFIG_GPIO_CDEV_V1 */
 
+/**
+ * struct edge_detector - contains the state of a line edge detector
+ * @line: the corresponding line request
+ * @irq: the interrupt triggered in response to events on this GPIO
+ * @flags: the flags, GPIO_V2_LINE_FLAG_EDGE_RISING and/or
+ * GPIO_V2_LINE_FLAG_EDGE_FALLING, indicating the edge detection applied
+ * @timestamp: cache for the timestamp storing it between hardirq and IRQ
+ * thread, used to bring the timestamp close to the actual event
+ * @seqno: the seqno for the current edge event in the sequence of events
+ * for the corresponding line request. Ths is drawn from the @line.
+ * @line_seqno: the seqno for the current edge event in the sequence of
+ * events for this line.
+ */
+struct edge_detector {
+	struct line *line;
+	unsigned int irq;
+	u64 flags;
+	/*
+	 * timestamp and seqno are shared by edge_irq_handler() and
+	 * edge_irq_thread() which are themselves mutually exclusive.
+	 */
+	u64 timestamp;
+	u32 seqno;
+	u32 line_seqno;
+};
+
 /**
  * struct line - contains the state of a userspace line request
  * @gdev: the GPIO device the line request pertains to
  * @label: consumer label used to tag descriptors
  * @num_descs: the number of descriptors held in the descs array
+ * @wait: wait queue that handles blocking reads of events
+ * @events: KFIFO for the GPIO events
+ * @seqno: the sequence number for edge events generated on all lines in
+ * this line request.  Note that this is not used when @num_descs is 1, as
+ * the line_seqno is then the same and is cheaper to calculate.
+ * @edets: an array of edge detectors, of size @num_descs
  * @descs: the GPIO descriptors held by this line request, with @num_descs
  * elements.
  */
@@ -394,9 +426,146 @@ struct line {
 	struct gpio_device *gdev;
 	const char *label;
 	u32 num_descs;
+	wait_queue_head_t wait;
+	DECLARE_KFIFO_PTR(events, struct gpio_v2_line_event);
+	atomic_t seqno;
+	struct edge_detector *edets;
 	struct gpio_desc *descs[];
 };
 
+static inline struct gpio_desc *edge_detector_desc(
+		const struct edge_detector *edet)
+{
+	return edet->line->descs[edet - &edet->line->edets[0]];
+}
+
+static irqreturn_t edge_irq_thread(int irq, void *p)
+{
+	struct edge_detector *edet = p;
+	struct line *line = edet->line;
+	struct gpio_desc *desc = edge_detector_desc(edet);
+	struct gpio_v2_line_event le;
+	int ret;
+
+	/* Do not leak kernel stack to userspace */
+	memset(&le, 0, sizeof(le));
+
+	/*
+	 * We may be running from a nested threaded interrupt in which case
+	 * we didn't get the timestamp from edge_irq_handler().
+	 */
+	if (!edet->timestamp) {
+		le.timestamp = ktime_get_ns();
+		if (line->num_descs != 1)
+			edet->seqno = atomic_inc_return(&line->seqno);
+	} else {
+		le.timestamp = edet->timestamp;
+	}
+	edet->timestamp = 0;
+
+	if (edet->flags == (GPIO_V2_LINE_FLAG_EDGE_RISING |
+			    GPIO_V2_LINE_FLAG_EDGE_FALLING)) {
+		int level = gpiod_get_value_cansleep(desc);
+
+		if (level)
+			/* Emit low-to-high event */
+			le.id = GPIO_V2_LINE_EVENT_RISING_EDGE;
+		else
+			/* Emit high-to-low event */
+			le.id = GPIO_V2_LINE_EVENT_FALLING_EDGE;
+	} else if (edet->flags == GPIO_V2_LINE_FLAG_EDGE_RISING) {
+		/* Emit low-to-high event */
+		le.id = GPIO_V2_LINE_EVENT_RISING_EDGE;
+	} else if (edet->flags == GPIO_V2_LINE_FLAG_EDGE_FALLING) {
+		/* Emit high-to-low event */
+		le.id = GPIO_V2_LINE_EVENT_FALLING_EDGE;
+	} else {
+		return IRQ_NONE;
+	}
+	edet->line_seqno++;
+	le.line_seqno = edet->line_seqno;
+	le.seqno = (line->num_descs == 1) ? le.line_seqno : edet->seqno;
+	le.offset = gpio_chip_hwgpio(desc);
+
+	ret = kfifo_in_spinlocked_noirqsave(&line->events, &le,
+					    1, &line->wait.lock);
+	if (ret)
+		wake_up_poll(&line->wait, EPOLLIN);
+	else
+		pr_debug_ratelimited("event FIFO is full - event dropped\n");
+
+	return IRQ_HANDLED;
+}
+
+static irqreturn_t edge_irq_handler(int irq, void *p)
+{
+	struct edge_detector *edet = p;
+	struct line *line = edet->line;
+
+	/*
+	 * Just store the timestamp in hardirq context so we get it as
+	 * close in time as possible to the actual event.
+	 */
+	edet->timestamp = ktime_get_ns();
+
+	if (line->num_descs != 1)
+		edet->seqno = atomic_inc_return(&line->seqno);
+
+	return IRQ_WAKE_THREAD;
+}
+
+static int edge_detector_start(struct edge_detector *edet)
+{
+	int ret, irq, irqflags = 0;
+	struct gpio_desc *desc;
+
+	desc = edge_detector_desc(edet);
+	irq = gpiod_to_irq(desc);
+
+	if (irq <= 0)
+		return -ENODEV;
+
+	edet->seqno = 0;
+	edet->line_seqno = 0;
+
+	if (edet->flags & GPIO_V2_LINE_FLAG_EDGE_RISING)
+		irqflags |= test_bit(FLAG_ACTIVE_LOW, &desc->flags) ?
+			IRQF_TRIGGER_FALLING : IRQF_TRIGGER_RISING;
+	if (edet->flags & GPIO_V2_LINE_FLAG_EDGE_FALLING)
+		irqflags |= test_bit(FLAG_ACTIVE_LOW, &desc->flags) ?
+			IRQF_TRIGGER_RISING : IRQF_TRIGGER_FALLING;
+	irqflags |= IRQF_ONESHOT;
+
+	/* Request a thread to read the events */
+	ret = request_threaded_irq(irq,
+				   edge_irq_handler,
+				   edge_irq_thread,
+				   irqflags,
+				   edet->line->label,
+				   edet);
+	if (ret)
+		return ret;
+
+	edet->irq = irq;
+	return 0;
+}
+
+static void edge_detector_stop(struct edge_detector *edet)
+{
+	if (edet->irq) {
+		free_irq(edet->irq, edet);
+		edet->irq = 0;
+	}
+}
+
+static int edge_detector_setup(struct edge_detector *edet,
+			       struct gpio_v2_line_config *lc)
+{
+	if (edet->flags)
+		return edge_detector_start(edet);
+	return 0;
+}
+
 #define GPIO_V2_LINE_BIAS_FLAGS \
 	(GPIO_V2_LINE_FLAG_BIAS_PULL_UP | \
 	 GPIO_V2_LINE_FLAG_BIAS_PULL_DOWN | \
@@ -410,10 +579,15 @@ struct line {
 	(GPIO_V2_LINE_FLAG_OPEN_DRAIN | \
 	 GPIO_V2_LINE_FLAG_OPEN_SOURCE)
 
+#define GPIO_V2_LINE_EDGE_FLAGS \
+	(GPIO_V2_LINE_FLAG_EDGE_RISING | \
+	 GPIO_V2_LINE_FLAG_EDGE_FALLING)
+
 #define GPIO_V2_LINE_VALID_FLAGS \
 	(GPIO_V2_LINE_FLAG_ACTIVE_LOW | \
 	 GPIO_V2_LINE_DIRECTION_FLAGS | \
 	 GPIO_V2_LINE_DRIVE_FLAGS | \
+	 GPIO_V2_LINE_EDGE_FLAGS | \
 	 GPIO_V2_LINE_BIAS_FLAGS)
 
 static u64 gpio_v2_line_config_flags(struct gpio_v2_line_config *lc,
@@ -430,6 +604,21 @@ static u64 gpio_v2_line_config_flags(struct gpio_v2_line_config *lc,
 	return lc->flags;
 }
 
+static int gpio_v2_line_config_has_edge_detection(struct gpio_v2_line_config *lc)
+{
+	int i;
+
+	if (lc->flags & GPIO_V2_LINE_EDGE_FLAGS)
+		return 1;
+
+	for (i = 0; i < lc->num_attrs; i--) {
+		if ((lc->attrs[i].attr.id == GPIO_V2_LINE_ATTR_ID_FLAGS) &&
+		    (lc->attrs[i].attr.flags & GPIO_V2_LINE_EDGE_FLAGS))
+			return 1;
+	}
+	return 0;
+}
+
 static int gpio_v2_line_config_output_value(struct gpio_v2_line_config *lc,
 					    int line_idx)
 {
@@ -458,6 +647,11 @@ static int gpio_v2_line_flags_validate(u64 flags)
 	    (flags & GPIO_V2_LINE_FLAG_OUTPUT))
 		return -EINVAL;
 
+	/* Edge detection requires explicit input. */
+	if ((flags & GPIO_V2_LINE_EDGE_FLAGS) &&
+	    !(flags & GPIO_V2_LINE_FLAG_INPUT))
+		return -EINVAL;
+
 	/*
 	 * Do not allow OPEN_SOURCE & OPEN_DRAIN flags in a single request. If
 	 * the hardware actually supports enabling both at the same time the
@@ -518,6 +712,10 @@ static void gpio_v2_line_config_flags_to_desc_flags(u64 flags,
 		set_bit(FLAG_IS_OUT, flagsp);
 	else if (flags & GPIO_V2_LINE_FLAG_INPUT)
 		clear_bit(FLAG_IS_OUT, flagsp);
+	assign_bit(FLAG_EDGE_RISING, flagsp,
+		   flags & GPIO_V2_LINE_FLAG_EDGE_RISING);
+	assign_bit(FLAG_EDGE_FALLING, flagsp,
+		   flags & GPIO_V2_LINE_FLAG_EDGE_FALLING);
 	assign_bit(FLAG_OPEN_DRAIN, flagsp,
 		   flags & GPIO_V2_LINE_FLAG_OPEN_DRAIN);
 	assign_bit(FLAG_OPEN_SOURCE, flagsp,
@@ -605,14 +803,87 @@ static long line_ioctl_compat(struct file *file, unsigned int cmd,
 }
 #endif
 
+static __poll_t line_poll(struct file *file,
+			  struct poll_table_struct *wait)
+{
+	struct line *line = file->private_data;
+	__poll_t events = 0;
+
+	poll_wait(file, &line->wait, wait);
+
+	if (!kfifo_is_empty_spinlocked_noirqsave(&line->events,
+						 &line->wait.lock))
+		events = EPOLLIN | EPOLLRDNORM;
+
+	return events;
+}
+
+static ssize_t line_read(struct file *file,
+			 char __user *buf,
+			 size_t count,
+			 loff_t *f_ps)
+{
+	struct line *line = file->private_data;
+	struct gpio_v2_line_event le;
+	ssize_t bytes_read = 0;
+	int ret;
+
+	if (count < sizeof(le))
+		return -EINVAL;
+
+	do {
+		spin_lock(&line->wait.lock);
+		if (kfifo_is_empty(&line->events)) {
+			if (bytes_read) {
+				spin_unlock(&line->wait.lock);
+				return bytes_read;
+			}
+
+			if (file->f_flags & O_NONBLOCK) {
+				spin_unlock(&line->wait.lock);
+				return -EAGAIN;
+			}
+
+			ret = wait_event_interruptible_locked(line->wait,
+					!kfifo_is_empty(&line->events));
+			if (ret) {
+				spin_unlock(&line->wait.lock);
+				return ret;
+			}
+		}
+
+		ret = kfifo_out(&line->events, &le, 1);
+		spin_unlock(&line->wait.lock);
+		if (ret != 1) {
+			/*
+			 * This should never happen - we were holding the
+			 * lock from the moment we learned the fifo is no
+			 * longer empty until now.
+			 */
+			ret = -EIO;
+			break;
+		}
+
+		if (copy_to_user(buf + bytes_read, &le, sizeof(le)))
+			return -EFAULT;
+		bytes_read += sizeof(le);
+	} while (count >= bytes_read + sizeof(le));
+
+	return bytes_read;
+}
+
 static void line_free(struct line *line)
 {
 	int i;
 
 	for (i = 0; i < line->num_descs; i++) {
+		if (line->edets)
+			edge_detector_stop(&line->edets[i]);
 		if (line->descs[i])
 			gpiod_free(line->descs[i]);
 	}
+	kfifo_free(&line->events);
+	kfree(line->edets);
 	kfree(line->label);
 	put_device(&line->gdev->dev);
 	kfree(line);
@@ -628,6 +899,8 @@ static int line_release(struct inode *inode, struct file *file)
 
 static const struct file_operations line_fileops = {
 	.release = line_release,
+	.read = line_read,
+	.poll = line_poll,
 	.owner = THIS_MODULE,
 	.llseek = noop_llseek,
 	.unlocked_ioctl = line_ioctl,
@@ -641,7 +914,7 @@ static int line_create(struct gpio_device *gdev, void __user *ip)
 	struct gpio_v2_line_request lr;
 	struct line *line;
 	struct file *file;
-	int fd, i, ret;
+	int fd, i, ret, size, has_edge_detection;
 	struct gpio_v2_line_config *lc;
 	unsigned long flags;
 
@@ -658,6 +931,11 @@ static int line_create(struct gpio_device *gdev, void __user *ip)
 	if (ret)
 		return ret;
 
+	/* event_buffer_size only valid with edge detection */
+	has_edge_detection = gpio_v2_line_config_has_edge_detection(lc);
+	if (lr.event_buffer_size && !has_edge_detection)
+		return -EINVAL;
+
 	line = kzalloc(struct_size(line, descs, lr.num_lines),
 		       GFP_KERNEL);
 	if (!line)
@@ -666,6 +944,16 @@ static int line_create(struct gpio_device *gdev, void __user *ip)
 	line->gdev = gdev;
 	get_device(&gdev->dev);
 
+	line->edets = kcalloc(lr.num_lines, sizeof(*line->edets),
+			      GFP_KERNEL);
+	if (!line->edets) {
+		ret = -ENOMEM;
+		goto out_free_line;
+	}
+
+	for (i = 0; i < lr.num_lines; i++)
+		line->edets[i].line = line;
+
 	/* Make sure this is terminated */
 	lr.consumer[sizeof(lr.consumer)-1] = '\0';
 	if (strlen(lr.consumer)) {
@@ -676,6 +964,21 @@ static int line_create(struct gpio_device *gdev, void __user *ip)
 		}
 	}
 
+	init_waitqueue_head(&line->wait);
+	if (has_edge_detection) {
+		size = lr.event_buffer_size;
+
+		if (size > GPIO_V2_LINES_MAX*16)
+			size = GPIO_V2_LINES_MAX*16;
+		else if (size == 0)
+			size = lr.num_lines*16;
+
+		ret = kfifo_alloc(&line->events, size, GFP_KERNEL);
+		if (ret)
+			goto out_free_line;
+	}
+
+	atomic_set(&line->seqno, 0);
 	line->num_descs = lr.num_lines;
 
 	/* Request each GPIO */
@@ -714,6 +1017,10 @@ static int line_create(struct gpio_device *gdev, void __user *ip)
 			ret = gpiod_direction_input(desc);
 			if (ret)
 				goto out_free_line;
+			line->edets[i].flags = flags & GPIO_V2_LINE_EDGE_FLAGS;
+			ret = edge_detector_setup(&line->edets[i], lc);
+			if (ret)
+				goto out_free_line;
 		}
 
 		blocking_notifier_call_chain(&desc->gdev->notifier,
@@ -1237,6 +1544,13 @@ static void gpio_desc_to_lineinfo(struct gpio_desc *desc,
 	if (test_bit(FLAG_PULL_UP, &desc->flags))
 		info->flags |= GPIO_V2_LINE_FLAG_BIAS_PULL_UP;
 
+	if (test_bit(FLAG_EDGE_RISING, &desc->flags))
+		info->flags |= GPIO_V2_LINE_FLAG_EDGE_RISING;
+	if (test_bit(FLAG_EDGE_FALLING, &desc->flags))
+		info->flags |= GPIO_V2_LINE_FLAG_EDGE_FALLING;
+
+	info->num_attrs = 0;
+
 	spin_unlock_irqrestore(&gpio_lock, flags);
 }
 
diff --git a/drivers/gpio/gpiolib.c b/drivers/gpio/gpiolib.c
index 80137c1b3cdc..e4c81dca7f8b 100644
--- a/drivers/gpio/gpiolib.c
+++ b/drivers/gpio/gpiolib.c
@@ -2041,6 +2041,8 @@ static bool gpiod_free_commit(struct gpio_desc *desc)
 		clear_bit(FLAG_PULL_UP, &desc->flags);
 		clear_bit(FLAG_PULL_DOWN, &desc->flags);
 		clear_bit(FLAG_BIAS_DISABLE, &desc->flags);
+		clear_bit(FLAG_EDGE_RISING, &desc->flags);
+		clear_bit(FLAG_EDGE_FALLING, &desc->flags);
 		clear_bit(FLAG_IS_HOGGED, &desc->flags);
 #ifdef CONFIG_OF_DYNAMIC
 		desc->hog = NULL;
diff --git a/drivers/gpio/gpiolib.h b/drivers/gpio/gpiolib.h
index 6709f79c02dd..39b356160937 100644
--- a/drivers/gpio/gpiolib.h
+++ b/drivers/gpio/gpiolib.h
@@ -114,6 +114,8 @@ struct gpio_desc {
 #define FLAG_PULL_UP    13	/* GPIO has pull up enabled */
 #define FLAG_PULL_DOWN  14	/* GPIO has pull down enabled */
 #define FLAG_BIAS_DISABLE    15	/* GPIO has pull disabled */
+#define FLAG_EDGE_RISING     16	/* GPIO CDEV detects rising edge events */
+#define FLAG_EDGE_FALLING    17	/* GPIO CDEV detects falling edge events */
 
 	/* Connection label */
 	const char		*label;
-- 
2.28.0

[PATCH v4 10/20] gpiolib: cdev: support GPIO_V2_LINE_SET_CONFIG_IOCTL

[Kent Gibson]

Add support for GPIO_V2_LINE_SET_CONFIG_IOCTL, the uAPI v2
line set config ioctl.

Signed-off-by: Kent Gibson <warthog618@gmail.com>
---
 drivers/gpio/gpiolib-cdev.c | 92 +++++++++++++++++++++++++++++++++++++
 1 file changed, 92 insertions(+)

diff --git a/drivers/gpio/gpiolib-cdev.c b/drivers/gpio/gpiolib-cdev.c
index 1d42a01f5414..04472c2b6678 100644
--- a/drivers/gpio/gpiolib-cdev.c
+++ b/drivers/gpio/gpiolib-cdev.c
@@ -16,6 +16,7 @@
 #include <linux/kernel.h>
 #include <linux/kfifo.h>
 #include <linux/module.h>
+#include <linux/mutex.h>
 #include <linux/pinctrl/consumer.h>
 #include <linux/poll.h>
 #include <linux/spinlock.h>
@@ -418,6 +419,8 @@ struct edge_detector {
  * @seqno: the sequence number for edge events generated on all lines in
  * this line request.  Note that this is not used when @num_descs is 1, as
  * the line_seqno is then the same and is cheaper to calculate.
+ * @config_mutex: mutex for serializing ioctl() calls to ensure consistency
+ * of configuration, particularly multi-step accesses to desc flags.
  * @edets: an array of edge detectors, of size @num_descs
  * @descs: the GPIO descriptors held by this line request, with @num_descs
  * elements.
@@ -429,6 +432,7 @@ struct line {
 	wait_queue_head_t wait;
 	DECLARE_KFIFO_PTR(events, struct gpio_v2_line_event);
 	atomic_t seqno;
+	struct mutex config_mutex;
 	struct edge_detector *edets;
 	struct gpio_desc *descs[];
 };
@@ -703,6 +707,30 @@ static int gpio_v2_line_config_validate(struct gpio_v2_line_config *lc,
 	return 0;
 }
 
+static int gpio_v2_line_config_change_validate(struct line *line,
+					       struct gpio_v2_line_config *lc)
+{
+	int i;
+	u64 flags;
+	struct gpio_desc *desc;
+
+	for (i = 0; i < line->num_descs; i++) {
+		desc = line->descs[i];
+		flags = gpio_v2_line_config_flags(lc, i);
+		/* disallow edge detection changes */
+		if (line->edets[i].flags != (flags & GPIO_V2_LINE_EDGE_FLAGS))
+			return -EINVAL;
+
+		if (line->edets[i].flags) {
+			/* disallow polarity changes */
+			if (test_bit(FLAG_ACTIVE_LOW, &desc->flags) !=
+			    ((flags & GPIO_V2_LINE_FLAG_ACTIVE_LOW) != 0))
+				return -EINVAL;
+		}
+	}
+	return 0;
+}
+
 static void gpio_v2_line_config_flags_to_desc_flags(u64 flags,
 						    unsigned long *flagsp)
 {
@@ -783,6 +811,67 @@ static long line_get_values(struct line *line, void __user *ip)
 	return 0;
 }
 
+static long line_set_config_locked(struct line *line,
+				   struct gpio_v2_line_config *lc)
+{
+	struct gpio_desc *desc;
+	int i, ret;
+	u64 flags;
+
+	ret = gpio_v2_line_config_change_validate(line, lc);
+	if (ret)
+		return ret;
+
+	for (i = 0; i < line->num_descs; i++) {
+		desc = line->descs[i];
+		flags = gpio_v2_line_config_flags(lc, i);
+
+		gpio_v2_line_config_flags_to_desc_flags(flags, &desc->flags);
+		/*
+		 * Lines have to be requested explicitly for input
+		 * or output, else the line will be treated "as is".
+		 */
+		if (flags & GPIO_V2_LINE_FLAG_OUTPUT) {
+			int val = gpio_v2_line_config_output_value(lc, i);
+
+			edge_detector_stop(&line->edets[i]);
+			ret = gpiod_direction_output(desc, val);
+			if (ret)
+				return ret;
+		} else if (flags & GPIO_V2_LINE_FLAG_INPUT) {
+			ret = gpiod_direction_input(desc);
+			if (ret)
+				return ret;
+		}
+
+		blocking_notifier_call_chain(&desc->gdev->notifier,
+					     GPIO_V2_LINE_CHANGED_CONFIG,
+					     desc);
+	}
+	return 0;
+}
+
+static long line_set_config(struct line *line, void __user *ip)
+{
+	struct gpio_v2_line_config lc;
+	int ret;
+
+	if (copy_from_user(&lc, ip, sizeof(lc)))
+		return -EFAULT;
+
+	ret = gpio_v2_line_config_validate(&lc, line->num_descs);
+	if (ret)
+		return ret;
+
+	mutex_lock(&line->config_mutex);
+
+	ret = line_set_config_locked(line, &lc);
+
+	mutex_unlock(&line->config_mutex);
+
+	return ret;
+}
+
 static long line_ioctl(struct file *file, unsigned int cmd,
 		       unsigned long arg)
 {
@@ -791,6 +880,8 @@ static long line_ioctl(struct file *file, unsigned int cmd,
 
 	if (cmd == GPIO_V2_LINE_GET_VALUES_IOCTL)
 		return line_get_values(line, ip);
+	else if (cmd == GPIO_V2_LINE_SET_CONFIG_IOCTL)
+		return line_set_config(line, ip);
 
 	return -EINVAL;
 }
@@ -964,6 +1055,7 @@ static int line_create(struct gpio_device *gdev, void __user *ip)
 		}
 	}
 
+	mutex_init(&line->config_mutex);
 	init_waitqueue_head(&line->wait);
 	if (has_edge_detection) {
 		size = lr.event_buffer_size;
-- 
2.28.0

[PATCH v4 11/20] gpiolib: cdev: support GPIO_V2_LINE_SET_VALUES_IOCTL

[Kent Gibson]

Add support for the GPIO_V2_LINE_SET_VALUES_IOCTL.

Signed-off-by: Kent Gibson <warthog618@gmail.com>
---
 drivers/gpio/gpiolib-cdev.c | 67 +++++++++++++++++++++++++++++++++++++
 1 file changed, 67 insertions(+)

diff --git a/drivers/gpio/gpiolib-cdev.c b/drivers/gpio/gpiolib-cdev.c
index 04472c2b6678..de88b7a5ba0f 100644
--- a/drivers/gpio/gpiolib-cdev.c
+++ b/drivers/gpio/gpiolib-cdev.c
@@ -811,6 +811,71 @@ static long line_get_values(struct line *line, void __user *ip)
 	return 0;
 }
 
+static long line_set_values_locked(struct line *line,
+				   struct gpio_v2_line_values *lv)
+{
+	DECLARE_BITMAP(vals, GPIO_V2_LINES_MAX);
+	struct gpio_desc **descs;
+	int ret, i, didx, num_set = 0;
+
+	bitmap_zero(vals, GPIO_V2_LINES_MAX);
+	for (i = 0; i < line->num_descs; i++) {
+		if (lv->mask & BIT_ULL(i)) {
+			if (!test_bit(FLAG_IS_OUT, &line->descs[i]->flags))
+				return -EPERM;
+			if (lv->bits & BIT_ULL(i))
+				__set_bit(num_set, vals);
+			num_set++;
+		}
+	}
+	if (num_set == 0)
+		return -EINVAL;
+
+	if (num_set == line->num_descs)
+		/* Reuse the array setting function */
+		return gpiod_set_array_value_complex(false,
+						     true,
+						     line->num_descs,
+						     line->descs,
+						     NULL,
+						     vals);
+
+	/* build compacted desc array and values */
+	descs = kmalloc_array(num_set, sizeof(*descs), GFP_KERNEL);
+	for (didx = 0, i = 0; i < line->num_descs; i++) {
+		if (lv->mask & BIT_ULL(i)) {
+			descs[didx] = line->descs[i];
+			didx++;
+		}
+	}
+	ret = gpiod_set_array_value_complex(false,
+					    true,
+					    num_set,
+					    descs,
+					    NULL,
+					    vals);
+
+	kfree(descs);
+	return ret;
+}
+
+static long line_set_values(struct line *line, void __user *ip)
+{
+	struct gpio_v2_line_values lv;
+	int ret;
+
+	if (copy_from_user(&lv, ip, sizeof(lv)))
+		return -EFAULT;
+
+	mutex_lock(&line->config_mutex);
+
+	ret = line_set_values_locked(line, &lv);
+
+	mutex_unlock(&line->config_mutex);
+
+	return ret;
+}
+
 static long line_set_config_locked(struct line *line,
 				   struct gpio_v2_line_config *lc)
 {
@@ -880,6 +945,8 @@ static long line_ioctl(struct file *file, unsigned int cmd,
 
 	if (cmd == GPIO_V2_LINE_GET_VALUES_IOCTL)
 		return line_get_values(line, ip);
+	else if (cmd == GPIO_V2_LINE_SET_VALUES_IOCTL)
+		return line_set_values(line, ip);
 	else if (cmd == GPIO_V2_LINE_SET_CONFIG_IOCTL)
 		return line_set_config(line, ip);
 
-- 
2.28.0

[PATCH v4 12/20] gpiolib: cdev: support setting debounce

[Kent Gibson]

Add support for setting debounce on a line via the GPIO uAPI.
Where debounce is not supported by hardware, a software debounce is
provided.

Signed-off-by: Kent Gibson <warthog618@gmail.com>
---

The implementation of the software debouncer waits for the line to be
stable for the debounce period before determining if a level change,
and a corresponding edge event, has occurred.  This provides maximum
protection against glitches, but also introduces a debounce_period
latency to edge events.

The software debouncer is integrated with the edge detection as it
utilises the line interrupt, and integration is simpler than getting
the two to interwork.  Where software debounce AND edge detection is
required, the debouncer provides both.

Due to the tight integration between the debouncer and edge detection,
and to avoid particular corner cases, it is not allowed to alter the
debounce value if edge detection is enabled.  Changing the debounce with
edge detection enabled is a very unlikely use case, so it is preferable
to disallow it rather than complicate the code to allow it.
Should the user wish to alter the debounce value in such cases they will
need to release and re-request the line.

Changes for v4:
 - fix handling of mask in line_get_values

Changes for v3:
 - only GPIO_V2 field renaming

Changes for v2:
 - improve documentation on fields shared by threads.
 - use READ_ONCE/WRITE_ONCE for shared fields rather than atomic_t
   which was overkill.

 drivers/gpio/gpiolib-cdev.c | 265 +++++++++++++++++++++++++++++++++++-
 drivers/gpio/gpiolib.h      |   4 +
 2 files changed, 263 insertions(+), 6 deletions(-)

diff --git a/drivers/gpio/gpiolib-cdev.c b/drivers/gpio/gpiolib-cdev.c
index de88b7a5ba0f..77fabf815de8 100644
--- a/drivers/gpio/gpiolib-cdev.c
+++ b/drivers/gpio/gpiolib-cdev.c
@@ -6,6 +6,7 @@
 #include <linux/build_bug.h>
 #include <linux/cdev.h>
 #include <linux/compat.h>
+#include <linux/compiler.h>
 #include <linux/device.h>
 #include <linux/err.h>
 #include <linux/file.h>
@@ -22,6 +23,7 @@
 #include <linux/spinlock.h>
 #include <linux/timekeeping.h>
 #include <linux/uaccess.h>
+#include <linux/workqueue.h>
 #include <uapi/linux/gpio.h>
 
 #include "gpiolib.h"
@@ -395,6 +397,9 @@ static int linehandle_create(struct gpio_device *gdev, void __user *ip)
  * for the corresponding line request. Ths is drawn from the @line.
  * @line_seqno: the seqno for the current edge event in the sequence of
  * events for this line.
+ * @work: the worker that implements software debouncing
+ * @sw_debounced: flag indicating if the software debouncer is active
+ * @level: the current debounced physical level of the line
  */
 struct edge_detector {
 	struct line *line;
@@ -406,7 +411,27 @@ struct edge_detector {
 	 */
 	u64 timestamp;
 	u32 seqno;
+	/*
+	 * line_seqno is used by either edge_irq_thread() or
+	 * debounce_work_func() which are themselves mutually exclusive.
+	 */
 	u32 line_seqno;
+	/*
+	 * -- debouncer specific fields --
+	 */
+	struct delayed_work work;
+	/*
+	 * sw_debounce is shared by line_set_config(), which is the only
+	 * setter, and line_ioctl(), which can live with a slightly stale
+	 * value.
+	 */
+	unsigned int sw_debounced;
+	/*
+	 * level is shared by debounce_work_func(), which is the only
+	 * setter, and line_ioctl() which can live with a slightly stale
+	 * value.
+	 */
+	unsigned int level;
 };
 
 /**
@@ -523,6 +548,10 @@ static int edge_detector_start(struct edge_detector *edet)
 	int ret, irq, irqflags = 0;
 	struct gpio_desc *desc;
 
+	if (READ_ONCE(edet->sw_debounced))
+		/* debouncer is setup and will provide edge detection */
+		return 0;
+
 	desc = edge_detector_desc(edet);
 	irq = gpiod_to_irq(desc);
 
@@ -554,17 +583,215 @@ static int edge_detector_start(struct edge_detector *edet)
 	return 0;
 }
 
+/*
+ * returns the current debounced logical value.
+ */
+static int debounced_value(struct edge_detector *edet)
+{
+	int value;
+
+	/*
+	 * minor race - debouncer may be stopped here, so edge_detector_stop
+	 * must leave the value unchanged so the following will read the level
+	 * from when the debouncer was last running.
+	 */
+	value = READ_ONCE(edet->level);
+
+	if (test_bit(FLAG_ACTIVE_LOW, &edge_detector_desc(edet)->flags))
+		value = !value;
+
+	return value;
+}
+
+static irqreturn_t debounce_irq_handler(int irq, void *p)
+{
+	struct edge_detector *edet = p;
+	struct gpio_desc *desc = edge_detector_desc(edet);
+
+	mod_delayed_work(system_wq,
+			 &edet->work,
+			 usecs_to_jiffies(READ_ONCE(desc->debounce_period)));
+
+	return IRQ_HANDLED;
+}
+
+static void debounce_work_func(struct work_struct *work)
+{
+	struct gpio_v2_line_event le;
+	int ret, level;
+	struct edge_detector *edet =
+		container_of(work, struct edge_detector, work.work);
+	struct gpio_desc *desc = edge_detector_desc(edet);
+	struct line *line;
+
+	level = gpiod_get_raw_value_cansleep(desc);
+	if (level < 0) {
+		pr_debug_ratelimited("debouncer failed to read line value\n");
+		return;
+	}
+
+	if (READ_ONCE(edet->level) == level)
+		return;
+
+	WRITE_ONCE(edet->level, level);
+
+	/* -- edge detection -- */
+	if (!edet->flags)
+		return;
+
+	/* switch from physical level to logical - if they differ */
+	if (test_bit(FLAG_ACTIVE_LOW, &desc->flags))
+		level = !level;
+
+	/* ignore edges that are not being monitored */
+	if (((edet->flags == GPIO_V2_LINE_FLAG_EDGE_RISING) && !level) ||
+	    ((edet->flags == GPIO_V2_LINE_FLAG_EDGE_FALLING) && level))
+		return;
+
+	/* Do not leak kernel stack to userspace */
+	memset(&le, 0, sizeof(le));
+
+	line = edet->line;
+	le.timestamp = ktime_get_ns();
+	le.offset = gpio_chip_hwgpio(desc);
+	edet->line_seqno++;
+	le.line_seqno = edet->line_seqno;
+	le.seqno = (line->num_descs == 1) ?
+		le.line_seqno : atomic_inc_return(&line->seqno);
+
+	if (level)
+		/* Emit low-to-high event */
+		le.id = GPIO_V2_LINE_EVENT_RISING_EDGE;
+	else
+		/* Emit high-to-low event */
+		le.id = GPIO_V2_LINE_EVENT_FALLING_EDGE;
+
+	ret = kfifo_in_spinlocked_noirqsave(&line->events, &le,
+					    1, &line->wait.lock);
+	if (ret)
+		wake_up_poll(&line->wait, EPOLLIN);
+	else
+		pr_debug_ratelimited("event FIFO is full - event dropped\n");
+}
+
+static int debounce_setup(struct edge_detector *edet,
+			  unsigned int debounce_period)
+{
+	int ret, level, irq, irqflags;
+	struct gpio_desc *desc = edge_detector_desc(edet);
+
+	/* try hardware */
+	ret = gpiod_set_debounce(desc, debounce_period);
+	if (!ret) {
+		WRITE_ONCE(desc->debounce_period, debounce_period);
+		return ret;
+	}
+	if (ret != -ENOTSUPP)
+		return ret;
+
+	if (debounce_period) {
+		/* setup software debounce */
+		level = gpiod_get_raw_value_cansleep(desc);
+		if (level < 0)
+			return level;
+
+		irq = gpiod_to_irq(desc);
+		if (irq <= 0)
+			return -ENODEV;
+
+		WRITE_ONCE(edet->level, level);
+		edet->line_seqno = 0;
+		irqflags = IRQF_TRIGGER_FALLING | IRQF_TRIGGER_RISING;
+		ret = request_irq(irq,
+				  debounce_irq_handler,
+				  irqflags,
+				  edet->line->label,
+				  edet);
+		if (ret)
+			return ret;
+
+		WRITE_ONCE(edet->sw_debounced, 1);
+		edet->irq = irq;
+	}
+	WRITE_ONCE(desc->debounce_period, debounce_period);
+	return 0;
+}
+
 static void edge_detector_stop(struct edge_detector *edet)
 {
+	struct gpio_desc *desc = edge_detector_desc(edet);
+
 	if (edet->irq) {
 		free_irq(edet->irq, edet);
 		edet->irq = 0;
 	}
+
+	cancel_delayed_work_sync(&edet->work);
+	WRITE_ONCE(edet->sw_debounced, 0);
+	/* do not change edet->level - see comment in debounced_value */
+
+	if (desc)
+		WRITE_ONCE(desc->debounce_period, 0);
+}
+
+static int debounce_update(struct edge_detector *edet,
+			   unsigned int debounce_period)
+{
+	struct gpio_desc *desc = edge_detector_desc(edet);
+
+	if (READ_ONCE(desc->debounce_period) == debounce_period)
+		return 0;
+
+	if (!READ_ONCE(edet->sw_debounced))
+		return debounce_setup(edet, debounce_period);
+
+	if (!debounce_period)
+		edge_detector_stop(edet);
+	else
+		WRITE_ONCE(desc->debounce_period, debounce_period);
+	return 0;
+}
+
+static int gpio_v2_line_config_debounced(struct gpio_v2_line_config *lc,
+					 int line_idx)
+{
+	int i;
+	unsigned long long mask = BIT_ULL(line_idx);
+
+	for (i = 0; i < lc->num_attrs; i++) {
+		if ((lc->attrs[i].attr.id == GPIO_V2_LINE_ATTR_ID_DEBOUNCE) &&
+		    (lc->attrs[i].mask & mask))
+			return 1;
+	}
+	return 0;
+}
+
+static u32 gpio_v2_line_config_debounce_period(struct gpio_v2_line_config *lc,
+					       int line_idx)
+{
+	int i;
+	unsigned long long mask = BIT_ULL(line_idx);
+
+	for (i = 0; i < lc->num_attrs; i++) {
+		if ((lc->attrs[i].attr.id == GPIO_V2_LINE_ATTR_ID_DEBOUNCE) &&
+		    (lc->attrs[i].mask & mask))
+			return lc->attrs[i].attr.debounce_period;
+	}
+	return 0;
 }
 
 static int edge_detector_setup(struct edge_detector *edet,
-			       struct gpio_v2_line_config *lc)
+			       struct gpio_v2_line_config *lc,
+			       int line_idx)
 {
+	int ret;
+
+	if (gpio_v2_line_config_debounced(lc, line_idx)) {
+		ret = debounce_setup(edet,
+			gpio_v2_line_config_debounce_period(lc, line_idx));
+		if (ret)
+			return ret;
+	}
 	if (edet->flags)
 		return edge_detector_start(edet);
 	return 0;
@@ -703,6 +930,11 @@ static int gpio_v2_line_config_validate(struct gpio_v2_line_config *lc,
 		ret = gpio_v2_line_flags_validate(flags);
 		if (ret)
 			return ret;
+
+		/* debounce requires explicit input */
+		if (gpio_v2_line_config_debounced(lc, i) &&
+		    !(flags & GPIO_V2_LINE_FLAG_INPUT))
+			return -EINVAL;
 	}
 	return 0;
 }
@@ -761,7 +993,7 @@ static long line_get_values(struct line *line, void __user *ip)
 	struct gpio_v2_line_values lv;
 	DECLARE_BITMAP(vals, GPIO_V2_LINES_MAX);
 	struct gpio_desc **descs;
-	int ret, i, didx, num_get = 0;
+	int ret, i, val, didx, num_get = 0;
 
 	/* NOTE: It's ok to read values of output lines. */
 	if (copy_from_user(&lv, ip, sizeof(lv)))
@@ -799,7 +1031,11 @@ static long line_get_values(struct line *line, void __user *ip)
 	lv.bits = 0;
 	for (didx = 0, i = 0; i < line->num_descs; i++) {
 		if (lv.mask & BIT_ULL(i)) {
-			if (test_bit(didx, vals))
+			if (line->edets[i].sw_debounced)
+				val = debounced_value(&line->edets[i]);
+			else
+				val = test_bit(didx, vals);
+			if (val)
 				lv.bits |= BIT_ULL(i);
 			didx++;
 		}
@@ -907,6 +1143,12 @@ static long line_set_config_locked(struct line *line,
 			ret = gpiod_direction_input(desc);
 			if (ret)
 				return ret;
+			if (gpio_v2_line_config_debounced(lc, i)) {
+				ret = debounce_update(&line->edets[i],
+					gpio_v2_line_config_debounce_period(lc, i));
+				if (ret)
+					return ret;
+			}
 		}
 
 		blocking_notifier_call_chain(&desc->gdev->notifier,
@@ -1109,8 +1351,11 @@ static int line_create(struct gpio_device *gdev, void __user *ip)
 		goto out_free_line;
 	}
 
-	for (i = 0; i < lr.num_lines; i++)
+	for (i = 0; i < lr.num_lines; i++) {
 		line->edets[i].line = line;
+		WRITE_ONCE(line->edets[i].sw_debounced, 0);
+		INIT_DELAYED_WORK(&line->edets[i].work, debounce_work_func);
+	}
 
 	/* Make sure this is terminated */
 	lr.consumer[sizeof(lr.consumer)-1] = '\0';
@@ -1177,7 +1422,7 @@ static int line_create(struct gpio_device *gdev, void __user *ip)
 			if (ret)
 				goto out_free_line;
 			line->edets[i].flags = flags & GPIO_V2_LINE_EDGE_FLAGS;
-			ret = edge_detector_setup(&line->edets[i], lc);
+			ret = edge_detector_setup(&line->edets[i], lc, i);
 			if (ret)
 				goto out_free_line;
 		}
@@ -1649,6 +1894,8 @@ static void gpio_desc_to_lineinfo(struct gpio_desc *desc,
 	struct gpio_chip *gc = desc->gdev->chip;
 	bool ok_for_pinctrl;
 	unsigned long flags;
+	u32 debounce_period;
+	int num_attrs = 0;
 
 	memset(info, 0, sizeof(*info));
 	info->offset = gpio_chip_hwgpio(desc);
@@ -1708,7 +1955,13 @@ static void gpio_desc_to_lineinfo(struct gpio_desc *desc,
 	if (test_bit(FLAG_EDGE_FALLING, &desc->flags))
 		info->flags |= GPIO_V2_LINE_FLAG_EDGE_FALLING;
 
-	info->num_attrs = 0;
+	debounce_period = READ_ONCE(desc->debounce_period);
+	if (debounce_period) {
+		info->attrs[num_attrs].id = GPIO_V2_LINE_ATTR_ID_DEBOUNCE;
+		info->attrs[num_attrs].debounce_period = debounce_period;
+		num_attrs++;
+	}
+	info->num_attrs = num_attrs;
 
 	spin_unlock_irqrestore(&gpio_lock, flags);
 }
diff --git a/drivers/gpio/gpiolib.h b/drivers/gpio/gpiolib.h
index 39b356160937..671805a79a15 100644
--- a/drivers/gpio/gpiolib.h
+++ b/drivers/gpio/gpiolib.h
@@ -124,6 +124,10 @@ struct gpio_desc {
 #ifdef CONFIG_OF_DYNAMIC
 	struct device_node	*hog;
 #endif
+#ifdef CONFIG_GPIO_CDEV
+	/* debounce period in microseconds */
+	unsigned int		debounce_period;
+#endif
 };
 
 int gpiod_request(struct gpio_desc *desc, const char *label);
-- 
2.28.0

[PATCH v4 13/20] gpio: uapi: document uAPI v1 as deprecated

[Kent Gibson]

Update uAPI documentation to deprecate v1 structs and ioctls.

Signed-off-by: Kent Gibson <warthog618@gmail.com>
---
 include/uapi/linux/gpio.h | 26 ++++++++++++++++++++++++++
 1 file changed, 26 insertions(+)

diff --git a/include/uapi/linux/gpio.h b/include/uapi/linux/gpio.h
index 0eb1f53b47e0..4af67415d73e 100644
--- a/include/uapi/linux/gpio.h
+++ b/include/uapi/linux/gpio.h
@@ -274,6 +274,9 @@ struct gpio_v2_line_event {
 
 /*
  *  ABI v1
+ *
+ * This version of the ABI is deprecated and will be removed in the future.
+ * Use the latest version of the ABI, defined above, instead.
  */
 
 /* Informational flags */
@@ -297,6 +300,9 @@ struct gpio_v2_line_event {
  * @consumer: a functional name for the consumer of this GPIO line as set by
  * whatever is using it, will be empty if there is no current user but may
  * also be empty if the consumer doesn't set this up
+ *
+ * This struct is part of ABI v1 and is deprecated.
+ * Use struct gpio_v2_line_info instead.
  */
 struct gpioline_info {
 	__u32 line_offset;
@@ -328,6 +334,9 @@ enum {
  * guarantee there are no implicit holes between it and subsequent members.
  * The 20-byte padding at the end makes sure we don't add any implicit padding
  * at the end of the structure on 64-bit architectures.
+ *
+ * This struct is part of ABI v1 and is deprecated.
+ * Use struct gpio_v2_line_info_changed instead.
  */
 struct gpioline_info_changed {
 	struct gpioline_info info;
@@ -367,6 +376,9 @@ struct gpioline_info_changed {
  * @fd: if successful this field will contain a valid anonymous file handle
  * after a GPIO_GET_LINEHANDLE_IOCTL operation, zero or negative value
  * means error
+ *
+ * This struct is part of ABI v1 and is deprecated.
+ * Use struct gpio_v2_line_request instead.
  */
 struct gpiohandle_request {
 	__u32 lineoffsets[GPIOHANDLES_MAX];
@@ -386,6 +398,9 @@ struct gpiohandle_request {
  * this specifies the default output value, should be 0 (low) or
  * 1 (high), anything else than 0 or 1 will be interpreted as 1 (high)
  * @padding: reserved for future use and should be zero filled
+ *
+ * This struct is part of ABI v1 and is deprecated.
+ * Use struct gpio_v2_line_config instead.
  */
 struct gpiohandle_config {
 	__u32 flags;
@@ -398,6 +413,9 @@ struct gpiohandle_config {
  * @values: when getting the state of lines this contains the current
  * state of a line, when setting the state of lines these should contain
  * the desired target state
+ *
+ * This struct is part of ABI v1 and is deprecated.
+ * Use struct gpio_v2_line_values instead.
  */
 struct gpiohandle_data {
 	__u8 values[GPIOHANDLES_MAX];
@@ -421,6 +439,9 @@ struct gpiohandle_data {
  * @fd: if successful this field will contain a valid anonymous file handle
  * after a GPIO_GET_LINEEVENT_IOCTL operation, zero or negative value
  * means error
+ *
+ * This struct is part of ABI v1 and is deprecated.
+ * Use struct gpio_v2_line_request instead.
  */
 struct gpioevent_request {
 	__u32 lineoffset;
@@ -440,6 +461,9 @@ struct gpioevent_request {
  * struct gpioevent_data - The actual event being pushed to userspace
  * @timestamp: best estimate of time of event occurrence, in nanoseconds
  * @id: event identifier
+ *
+ * This struct is part of ABI v1 and is deprecated.
+ * Use struct gpio_v2_line_event instead.
  */
 struct gpioevent_data {
 	__u64 timestamp;
@@ -464,6 +488,8 @@ struct gpioevent_data {
 
 /*
  * v1 ioctl()s
+ *
+ * These ioctl()s are deprecated.  Use the v2 equivalent instead.
  */
 #define GPIO_GET_LINEINFO_IOCTL _IOWR(0xB4, 0x02, struct gpioline_info)
 #define GPIO_GET_LINEHANDLE_IOCTL _IOWR(0xB4, 0x03, struct gpiohandle_request)
-- 
2.28.0

[PATCH v4 14/20] tools: gpio: port lsgpio to v2 uAPI

[Kent Gibson]

Port the lsgpio tool to the latest GPIO uAPI.

Signed-off-by: Kent Gibson <warthog618@gmail.com>
---
 tools/gpio/lsgpio.c | 60 ++++++++++++++++++++++++++++-----------------
 1 file changed, 38 insertions(+), 22 deletions(-)

diff --git a/tools/gpio/lsgpio.c b/tools/gpio/lsgpio.c
index b08d7a5e779b..deda38244026 100644
--- a/tools/gpio/lsgpio.c
+++ b/tools/gpio/lsgpio.c
@@ -25,57 +25,73 @@
 
 struct gpio_flag {
 	char *name;
-	unsigned long mask;
+	unsigned long long mask;
 };
 
 struct gpio_flag flagnames[] = {
 	{
-		.name = "kernel",
-		.mask = GPIOLINE_FLAG_KERNEL,
+		.name = "used",
+		.mask = GPIO_V2_LINE_FLAG_USED,
+	},
+	{
+		.name = "input",
+		.mask = GPIO_V2_LINE_FLAG_INPUT,
 	},
 	{
 		.name = "output",
-		.mask = GPIOLINE_FLAG_IS_OUT,
+		.mask = GPIO_V2_LINE_FLAG_OUTPUT,
 	},
 	{
 		.name = "active-low",
-		.mask = GPIOLINE_FLAG_ACTIVE_LOW,
+		.mask = GPIO_V2_LINE_FLAG_ACTIVE_LOW,
 	},
 	{
 		.name = "open-drain",
-		.mask = GPIOLINE_FLAG_OPEN_DRAIN,
+		.mask = GPIO_V2_LINE_FLAG_OPEN_DRAIN,
 	},
 	{
 		.name = "open-source",
-		.mask = GPIOLINE_FLAG_OPEN_SOURCE,
+		.mask = GPIO_V2_LINE_FLAG_OPEN_SOURCE,
 	},
 	{
 		.name = "pull-up",
-		.mask = GPIOLINE_FLAG_BIAS_PULL_UP,
+		.mask = GPIO_V2_LINE_FLAG_BIAS_PULL_UP,
 	},
 	{
 		.name = "pull-down",
-		.mask = GPIOLINE_FLAG_BIAS_PULL_DOWN,
+		.mask = GPIO_V2_LINE_FLAG_BIAS_PULL_DOWN,
 	},
 	{
 		.name = "bias-disabled",
-		.mask = GPIOLINE_FLAG_BIAS_DISABLE,
+		.mask = GPIO_V2_LINE_FLAG_BIAS_DISABLED,
 	},
 };
 
-void print_flags(unsigned long flags)
+static void print_attributes(struct gpio_v2_line_info *info)
 {
 	int i;
-	int printed = 0;
+	const char *field_format = "%s";
 
 	for (i = 0; i < ARRAY_SIZE(flagnames); i++) {
-		if (flags & flagnames[i].mask) {
-			if (printed)
-				fprintf(stdout, " ");
-			fprintf(stdout, "%s", flagnames[i].name);
-			printed++;
+		if (info->flags & flagnames[i].mask) {
+			fprintf(stdout, field_format, flagnames[i].name);
+			field_format = ", %s";
 		}
 	}
+
+	if ((info->flags & GPIO_V2_LINE_FLAG_EDGE_RISING) &&
+	    (info->flags & GPIO_V2_LINE_FLAG_EDGE_FALLING))
+		fprintf(stdout, field_format, "both-edges");
+	else if (info->flags & GPIO_V2_LINE_FLAG_EDGE_RISING)
+		fprintf(stdout, field_format, "rising-edge");
+	else if (info->flags & GPIO_V2_LINE_FLAG_EDGE_FALLING)
+		fprintf(stdout, field_format, "falling-edge");
+
+	for (i = 0; i < info->num_attrs; i++) {
+		if (info->attrs[i].id == GPIO_V2_LINE_ATTR_ID_DEBOUNCE)
+			fprintf(stdout, ", debounce_period=%dusec",
+				info->attrs[0].debounce_period);
+	}
 }
 
 int list_device(const char *device_name)
@@ -109,18 +125,18 @@ int list_device(const char *device_name)
 
 	/* Loop over the lines and print info */
 	for (i = 0; i < cinfo.lines; i++) {
-		struct gpioline_info linfo;
+		struct gpio_v2_line_info linfo;
 
 		memset(&linfo, 0, sizeof(linfo));
-		linfo.line_offset = i;
+		linfo.offset = i;
 
-		ret = ioctl(fd, GPIO_GET_LINEINFO_IOCTL, &linfo);
+		ret = ioctl(fd, GPIO_V2_GET_LINEINFO_IOCTL, &linfo);
 		if (ret == -1) {
 			ret = -errno;
 			perror("Failed to issue LINEINFO IOCTL\n");
 			goto exit_close_error;
 		}
-		fprintf(stdout, "\tline %2d:", linfo.line_offset);
+		fprintf(stdout, "\tline %2d:", linfo.offset);
 		if (linfo.name[0])
 			fprintf(stdout, " \"%s\"", linfo.name);
 		else
@@ -131,7 +147,7 @@ int list_device(const char *device_name)
 			fprintf(stdout, " unused");
 		if (linfo.flags) {
 			fprintf(stdout, " [");
-			print_flags(linfo.flags);
+			print_attributes(&linfo);
 			fprintf(stdout, "]");
 		}
 		fprintf(stdout, "\n");
-- 
2.28.0

[PATCH v4 15/20] tools: gpio: port gpio-watch to v2 uAPI

[Kent Gibson]

Port the gpio-watch tool to the latest GPIO uAPI.

Signed-off-by: Kent Gibson <warthog618@gmail.com>
---
 tools/gpio/gpio-watch.c | 16 ++++++++--------
 1 file changed, 8 insertions(+), 8 deletions(-)

diff --git a/tools/gpio/gpio-watch.c b/tools/gpio/gpio-watch.c
index 5cea24fddfa7..6f048350a27e 100644
--- a/tools/gpio/gpio-watch.c
+++ b/tools/gpio/gpio-watch.c
@@ -21,8 +21,8 @@
 
 int main(int argc, char **argv)
 {
-	struct gpioline_info_changed chg;
-	struct gpioline_info req;
+	struct gpio_v2_line_info_changed chg;
+	struct gpio_v2_line_info req;
 	struct pollfd pfd;
 	int fd, i, j, ret;
 	char *event, *end;
@@ -40,11 +40,11 @@ int main(int argc, char **argv)
 	for (i = 0, j = 2; i < argc - 2; i++, j++) {
 		memset(&req, 0, sizeof(req));
 
-		req.line_offset = strtoul(argv[j], &end, 0);
+		req.offset = strtoul(argv[j], &end, 0);
 		if (*end != '\0')
 			goto err_usage;
 
-		ret = ioctl(fd, GPIO_GET_LINEINFO_WATCH_IOCTL, &req);
+		ret = ioctl(fd, GPIO_V2_GET_LINEINFO_WATCH_IOCTL, &req);
 		if (ret) {
 			perror("unable to set up line watch");
 			return EXIT_FAILURE;
@@ -71,13 +71,13 @@ int main(int argc, char **argv)
 			}
 
 			switch (chg.event_type) {
-			case GPIOLINE_CHANGED_REQUESTED:
+			case GPIO_V2_LINE_CHANGED_REQUESTED:
 				event = "requested";
 				break;
-			case GPIOLINE_CHANGED_RELEASED:
+			case GPIO_V2_LINE_CHANGED_RELEASED:
 				event = "released";
 				break;
-			case GPIOLINE_CHANGED_CONFIG:
+			case GPIO_V2_LINE_CHANGED_CONFIG:
 				event = "config changed";
 				break;
 			default:
@@ -87,7 +87,7 @@ int main(int argc, char **argv)
 			}
 
 			printf("line %u: %s at %llu\n",
-			       chg.info.line_offset, event, chg.timestamp);
+			       chg.info.offset, event, chg.timestamp);
 		}
 	}
 
-- 
2.28.0

[PATCH v4 16/20] tools: gpio: rename nlines to num_lines

[Kent Gibson]

Rename nlines to num_lines to be consistent with other usage for fields
describing the number of entries in an array.

Signed-off-by: Kent Gibson <warthog618@gmail.com>
---
 tools/gpio/gpio-hammer.c | 26 +++++++++++++-------------
 tools/gpio/gpio-utils.c  | 20 ++++++++++----------
 tools/gpio/gpio-utils.h  |  6 +++---
 3 files changed, 26 insertions(+), 26 deletions(-)

diff --git a/tools/gpio/gpio-hammer.c b/tools/gpio/gpio-hammer.c
index 9fd926e8cb52..a2c7577fad5c 100644
--- a/tools/gpio/gpio-hammer.c
+++ b/tools/gpio/gpio-hammer.c
@@ -22,7 +22,7 @@
 #include <linux/gpio.h>
 #include "gpio-utils.h"
 
-int hammer_device(const char *device_name, unsigned int *lines, int nlines,
+int hammer_device(const char *device_name, unsigned int *lines, int num_lines,
 		  unsigned int loops)
 {
 	struct gpiohandle_data data;
@@ -33,7 +33,7 @@ int hammer_device(const char *device_name, unsigned int *lines, int nlines,
 	unsigned int iteration = 0;
 
 	memset(&data.values, 0, sizeof(data.values));
-	ret = gpiotools_request_linehandle(device_name, lines, nlines,
+	ret = gpiotools_request_linehandle(device_name, lines, num_lines,
 					   GPIOHANDLE_REQUEST_OUTPUT, &data,
 					   "gpio-hammer");
 	if (ret < 0)
@@ -46,15 +46,15 @@ int hammer_device(const char *device_name, unsigned int *lines, int nlines,
 		goto exit_close_error;
 
 	fprintf(stdout, "Hammer lines [");
-	for (i = 0; i < nlines; i++) {
+	for (i = 0; i < num_lines; i++) {
 		fprintf(stdout, "%d", lines[i]);
-		if (i != (nlines - 1))
+		if (i != (num_lines - 1))
 			fprintf(stdout, ", ");
 	}
 	fprintf(stdout, "] on %s, initial states: [", device_name);
-	for (i = 0; i < nlines; i++) {
+	for (i = 0; i < num_lines; i++) {
 		fprintf(stdout, "%d", data.values[i]);
-		if (i != (nlines - 1))
+		if (i != (num_lines - 1))
 			fprintf(stdout, ", ");
 	}
 	fprintf(stdout, "]\n");
@@ -63,7 +63,7 @@ int hammer_device(const char *device_name, unsigned int *lines, int nlines,
 	j = 0;
 	while (1) {
 		/* Invert all lines so we blink */
-		for (i = 0; i < nlines; i++)
+		for (i = 0; i < num_lines; i++)
 			data.values[i] = !data.values[i];
 
 		ret = gpiotools_set_values(fd, &data);
@@ -81,9 +81,9 @@ int hammer_device(const char *device_name, unsigned int *lines, int nlines,
 			j = 0;
 
 		fprintf(stdout, "[");
-		for (i = 0; i < nlines; i++) {
+		for (i = 0; i < num_lines; i++) {
 			fprintf(stdout, "%d: %d", lines[i], data.values[i]);
-			if (i != (nlines - 1))
+			if (i != (num_lines - 1))
 				fprintf(stdout, ", ");
 		}
 		fprintf(stdout, "]\r");
@@ -121,7 +121,7 @@ int main(int argc, char **argv)
 	const char *device_name = NULL;
 	unsigned int lines[GPIOHANDLES_MAX];
 	unsigned int loops = 0;
-	int nlines;
+	int num_lines;
 	int c;
 	int i;
 
@@ -158,11 +158,11 @@ int main(int argc, char **argv)
 		return -1;
 	}
 
-	nlines = i;
+	num_lines = i;
 
-	if (!device_name || !nlines) {
+	if (!device_name || !num_lines) {
 		print_usage();
 		return -1;
 	}
-	return hammer_device(device_name, lines, nlines, loops);
+	return hammer_device(device_name, lines, num_lines, loops);
 }
diff --git a/tools/gpio/gpio-utils.c b/tools/gpio/gpio-utils.c
index 16a5d9cb9da2..d527980bcb94 100644
--- a/tools/gpio/gpio-utils.c
+++ b/tools/gpio/gpio-utils.c
@@ -38,7 +38,7 @@
  *			such as "gpiochip0"
  * @lines:		An array desired lines, specified by offset
  *			index for the associated GPIO device.
- * @nline:		The number of lines to request.
+ * @num_lines:		The number of lines to request.
  * @flag:		The new flag for requsted gpio. Reference
  *			"linux/gpio.h" for the meaning of flag.
  * @data:		Default value will be set to gpio when flag is
@@ -56,7 +56,7 @@
  *			On failure return the errno.
  */
 int gpiotools_request_linehandle(const char *device_name, unsigned int *lines,
-				 unsigned int nlines, unsigned int flag,
+				 unsigned int num_lines, unsigned int flag,
 				 struct gpiohandle_data *data,
 				 const char *consumer_label)
 {
@@ -78,12 +78,12 @@ int gpiotools_request_linehandle(const char *device_name, unsigned int *lines,
 		goto exit_free_name;
 	}
 
-	for (i = 0; i < nlines; i++)
+	for (i = 0; i < num_lines; i++)
 		req.lineoffsets[i] = lines[i];
 
 	req.flags = flag;
 	strcpy(req.consumer_label, consumer_label);
-	req.lines = nlines;
+	req.lines = num_lines;
 	if (flag & GPIOHANDLE_REQUEST_OUTPUT)
 		memcpy(req.default_values, data, sizeof(req.default_values));
 
@@ -194,20 +194,20 @@ int gpiotools_get(const char *device_name, unsigned int line)
  *			such as "gpiochip0".
  * @lines:		An array desired lines, specified by offset
  *			index for the associated GPIO device.
- * @nline:		The number of lines to request.
+ * @num_lines:		The number of lines to request.
  * @data:		The array of values get from gpiochip.
  *
  * Return:		On success return 0;
  *			On failure return the errno.
  */
 int gpiotools_gets(const char *device_name, unsigned int *lines,
-		   unsigned int nlines, struct gpiohandle_data *data)
+		   unsigned int num_lines, struct gpiohandle_data *data)
 {
 	int fd;
 	int ret;
 	int ret_close;
 
-	ret = gpiotools_request_linehandle(device_name, lines, nlines,
+	ret = gpiotools_request_linehandle(device_name, lines, num_lines,
 					   GPIOHANDLE_REQUEST_INPUT, data,
 					   CONSUMER);
 	if (ret < 0)
@@ -245,7 +245,7 @@ int gpiotools_set(const char *device_name, unsigned int line,
  *			such as "gpiochip0".
  * @lines:		An array desired lines, specified by offset
  *			index for the associated GPIO device.
- * @nline:		The number of lines to request.
+ * @num_lines:		The number of lines to request.
  * @data:		The array of values set to gpiochip, must be
  *			0(low) or 1(high).
  *
@@ -253,11 +253,11 @@ int gpiotools_set(const char *device_name, unsigned int line,
  *			On failure return the errno.
  */
 int gpiotools_sets(const char *device_name, unsigned int *lines,
-		   unsigned int nlines, struct gpiohandle_data *data)
+		   unsigned int num_lines, struct gpiohandle_data *data)
 {
 	int ret;
 
-	ret = gpiotools_request_linehandle(device_name, lines, nlines,
+	ret = gpiotools_request_linehandle(device_name, lines, num_lines,
 					   GPIOHANDLE_REQUEST_OUTPUT, data,
 					   CONSUMER);
 	if (ret < 0)
diff --git a/tools/gpio/gpio-utils.h b/tools/gpio/gpio-utils.h
index cf37f13f3dcb..324729577865 100644
--- a/tools/gpio/gpio-utils.h
+++ b/tools/gpio/gpio-utils.h
@@ -23,7 +23,7 @@ static inline int check_prefix(const char *str, const char *prefix)
 }
 
 int gpiotools_request_linehandle(const char *device_name, unsigned int *lines,
-				 unsigned int nlines, unsigned int flag,
+				 unsigned int num_lines, unsigned int flag,
 				 struct gpiohandle_data *data,
 				 const char *consumer_label);
 int gpiotools_set_values(const int fd, struct gpiohandle_data *data);
@@ -32,10 +32,10 @@ int gpiotools_release_linehandle(const int fd);
 
 int gpiotools_get(const char *device_name, unsigned int line);
 int gpiotools_gets(const char *device_name, unsigned int *lines,
-		   unsigned int nlines, struct gpiohandle_data *data);
+		   unsigned int num_lines, struct gpiohandle_data *data);
 int gpiotools_set(const char *device_name, unsigned int line,
 		  unsigned int value);
 int gpiotools_sets(const char *device_name, unsigned int *lines,
-		   unsigned int nlines, struct gpiohandle_data *data);
+		   unsigned int num_lines, struct gpiohandle_data *data);
 
 #endif /* _GPIO_UTILS_H_ */
-- 
2.28.0

[PATCH v4 17/20] tools: gpio: port gpio-hammer to v2 uAPI

[Kent Gibson]

Port the gpio-hammer tool to the latest GPIO uAPI.

Signed-off-by: Kent Gibson <warthog618@gmail.com>
---
 tools/gpio/gpio-hammer.c |  32 +++++++----
 tools/gpio/gpio-utils.c  | 119 ++++++++++++++++++++++-----------------
 tools/gpio/gpio-utils.h  |  50 +++++++++++++---
 3 files changed, 128 insertions(+), 73 deletions(-)

diff --git a/tools/gpio/gpio-hammer.c b/tools/gpio/gpio-hammer.c
index a2c7577fad5c..54fdf59dd320 100644
--- a/tools/gpio/gpio-hammer.c
+++ b/tools/gpio/gpio-hammer.c
@@ -25,23 +25,30 @@
 int hammer_device(const char *device_name, unsigned int *lines, int num_lines,
 		  unsigned int loops)
 {
-	struct gpiohandle_data data;
+	struct gpio_v2_line_values values;
+	struct gpio_v2_line_config config;
 	char swirr[] = "-\\|/";
 	int fd;
 	int ret;
 	int i, j;
 	unsigned int iteration = 0;
 
-	memset(&data.values, 0, sizeof(data.values));
-	ret = gpiotools_request_linehandle(device_name, lines, num_lines,
-					   GPIOHANDLE_REQUEST_OUTPUT, &data,
-					   "gpio-hammer");
+	memset(&config, 0, sizeof(config));
+	config.flags = GPIO_V2_LINE_FLAG_OUTPUT;
+
+	ret = gpiotools_request_line(device_name, lines, num_lines,
+				     &config, "gpio-hammer");
 	if (ret < 0)
 		goto exit_error;
 	else
 		fd = ret;
 
-	ret = gpiotools_get_values(fd, &data);
+	values.mask = 0;
+	values.bits = 0;
+	for (i = 0; i < num_lines; i++)
+		gpiotools_set_bit(&values.mask, i);
+
+	ret = gpiotools_get_values(fd, &values);
 	if (ret < 0)
 		goto exit_close_error;
 
@@ -53,7 +60,7 @@ int hammer_device(const char *device_name, unsigned int *lines, int num_lines,
 	}
 	fprintf(stdout, "] on %s, initial states: [", device_name);
 	for (i = 0; i < num_lines; i++) {
-		fprintf(stdout, "%d", data.values[i]);
+		fprintf(stdout, "%d", gpiotools_test_bit(values.bits, i));
 		if (i != (num_lines - 1))
 			fprintf(stdout, ", ");
 	}
@@ -64,14 +71,14 @@ int hammer_device(const char *device_name, unsigned int *lines, int num_lines,
 	while (1) {
 		/* Invert all lines so we blink */
 		for (i = 0; i < num_lines; i++)
-			data.values[i] = !data.values[i];
+			gpiotools_change_bit(&values.bits, i);
 
-		ret = gpiotools_set_values(fd, &data);
+		ret = gpiotools_set_values(fd, &values);
 		if (ret < 0)
 			goto exit_close_error;
 
 		/* Re-read values to get status */
-		ret = gpiotools_get_values(fd, &data);
+		ret = gpiotools_get_values(fd, &values);
 		if (ret < 0)
 			goto exit_close_error;
 
@@ -82,7 +89,8 @@ int hammer_device(const char *device_name, unsigned int *lines, int num_lines,
 
 		fprintf(stdout, "[");
 		for (i = 0; i < num_lines; i++) {
-			fprintf(stdout, "%d: %d", lines[i], data.values[i]);
+			fprintf(stdout, "%d: %d", lines[i],
+				gpiotools_test_bit(values.bits, i));
 			if (i != (num_lines - 1))
 				fprintf(stdout, ", ");
 		}
@@ -97,7 +105,7 @@ int hammer_device(const char *device_name, unsigned int *lines, int num_lines,
 	ret = 0;
 
 exit_close_error:
-	gpiotools_release_linehandle(fd);
+	gpiotools_release_line(fd);
 exit_error:
 	return ret;
 }
diff --git a/tools/gpio/gpio-utils.c b/tools/gpio/gpio-utils.c
index d527980bcb94..68edc1a329e2 100644
--- a/tools/gpio/gpio-utils.c
+++ b/tools/gpio/gpio-utils.c
@@ -33,34 +33,32 @@
  * release these lines.
  */
 /**
- * gpiotools_request_linehandle() - request gpio lines in a gpiochip
+ * gpiotools_request_line() - request gpio lines in a gpiochip
  * @device_name:	The name of gpiochip without prefix "/dev/",
  *			such as "gpiochip0"
  * @lines:		An array desired lines, specified by offset
  *			index for the associated GPIO device.
  * @num_lines:		The number of lines to request.
- * @flag:		The new flag for requsted gpio. Reference
- *			"linux/gpio.h" for the meaning of flag.
- * @data:		Default value will be set to gpio when flag is
- *			GPIOHANDLE_REQUEST_OUTPUT.
- * @consumer_label:	The name of consumer, such as "sysfs",
+ * @config:		The new config for requested gpio. Reference
+ *			"linux/gpio.h" for config details.
+ * @consumer:		The name of consumer, such as "sysfs",
  *			"powerkey". This is useful for other users to
  *			know who is using.
  *
  * Request gpio lines through the ioctl provided by chardev. User
  * could call gpiotools_set_values() and gpiotools_get_values() to
  * read and write respectively through the returned fd. Call
- * gpiotools_release_linehandle() to release these lines after that.
+ * gpiotools_release_line() to release these lines after that.
  *
  * Return:		On success return the fd;
  *			On failure return the errno.
  */
-int gpiotools_request_linehandle(const char *device_name, unsigned int *lines,
-				 unsigned int num_lines, unsigned int flag,
-				 struct gpiohandle_data *data,
-				 const char *consumer_label)
+int gpiotools_request_line(const char *device_name, unsigned int *lines,
+			   unsigned int num_lines,
+			   struct gpio_v2_line_config *config,
+			   const char *consumer)
 {
-	struct gpiohandle_request req;
+	struct gpio_v2_line_request req;
 	char *chrdev_name;
 	int fd;
 	int i;
@@ -78,20 +76,19 @@ int gpiotools_request_linehandle(const char *device_name, unsigned int *lines,
 		goto exit_free_name;
 	}
 
+	memset(&req, 0, sizeof(req));
 	for (i = 0; i < num_lines; i++)
-		req.lineoffsets[i] = lines[i];
+		req.offsets[i] = lines[i];
 
-	req.flags = flag;
-	strcpy(req.consumer_label, consumer_label);
-	req.lines = num_lines;
-	if (flag & GPIOHANDLE_REQUEST_OUTPUT)
-		memcpy(req.default_values, data, sizeof(req.default_values));
+	req.config = *config;
+	strcpy(req.consumer, consumer);
+	req.num_lines = num_lines;
 
-	ret = ioctl(fd, GPIO_GET_LINEHANDLE_IOCTL, &req);
+	ret = ioctl(fd, GPIO_V2_GET_LINE_IOCTL, &req);
 	if (ret == -1) {
 		ret = -errno;
 		fprintf(stderr, "Failed to issue %s (%d), %s\n",
-			"GPIO_GET_LINEHANDLE_IOCTL", ret, strerror(errno));
+			"GPIO_GET_LINE_IOCTL", ret, strerror(errno));
 	}
 
 	if (close(fd) == -1)
@@ -103,17 +100,17 @@ int gpiotools_request_linehandle(const char *device_name, unsigned int *lines,
 /**
  * gpiotools_set_values(): Set the value of gpio(s)
  * @fd:			The fd returned by
- *			gpiotools_request_linehandle().
- * @data:		The array of values want to set.
+ *			gpiotools_request_line().
+ * @values:		The array of values want to set.
  *
  * Return:		On success return 0;
  *			On failure return the errno.
  */
-int gpiotools_set_values(const int fd, struct gpiohandle_data *data)
+int gpiotools_set_values(const int fd, struct gpio_v2_line_values *values)
 {
 	int ret;
 
-	ret = ioctl(fd, GPIOHANDLE_SET_LINE_VALUES_IOCTL, data);
+	ret = ioctl(fd, GPIO_V2_LINE_SET_VALUES_IOCTL, values);
 	if (ret == -1) {
 		ret = -errno;
 		fprintf(stderr, "Failed to issue %s (%d), %s\n",
@@ -127,17 +124,17 @@ int gpiotools_set_values(const int fd, struct gpiohandle_data *data)
 /**
  * gpiotools_get_values(): Get the value of gpio(s)
  * @fd:			The fd returned by
- *			gpiotools_request_linehandle().
- * @data:		The array of values get from hardware.
+ *			gpiotools_request_line().
+ * @values:		The array of values get from hardware.
  *
  * Return:		On success return 0;
  *			On failure return the errno.
  */
-int gpiotools_get_values(const int fd, struct gpiohandle_data *data)
+int gpiotools_get_values(const int fd, struct gpio_v2_line_values *values)
 {
 	int ret;
 
-	ret = ioctl(fd, GPIOHANDLE_GET_LINE_VALUES_IOCTL, data);
+	ret = ioctl(fd, GPIO_V2_LINE_GET_VALUES_IOCTL, values);
 	if (ret == -1) {
 		ret = -errno;
 		fprintf(stderr, "Failed to issue %s (%d), %s\n",
@@ -149,14 +146,14 @@ int gpiotools_get_values(const int fd, struct gpiohandle_data *data)
 }
 
 /**
- * gpiotools_release_linehandle(): Release the line(s) of gpiochip
+ * gpiotools_release_line(): Release the line(s) of gpiochip
  * @fd:			The fd returned by
- *			gpiotools_request_linehandle().
+ *			gpiotools_request_line().
  *
  * Return:		On success return 0;
  *			On failure return the errno.
  */
-int gpiotools_release_linehandle(const int fd)
+int gpiotools_release_line(const int fd)
 {
 	int ret;
 
@@ -180,11 +177,14 @@ int gpiotools_release_linehandle(const int fd)
  */
 int gpiotools_get(const char *device_name, unsigned int line)
 {
-	struct gpiohandle_data data;
+	int ret;
+	unsigned int value;
 	unsigned int lines[] = {line};
 
-	gpiotools_gets(device_name, lines, 1, &data);
-	return data.values[0];
+	ret = gpiotools_gets(device_name, lines, 1, &value);
+	if (ret)
+		return ret;
+	return value;
 }
 
 
@@ -195,27 +195,35 @@ int gpiotools_get(const char *device_name, unsigned int line)
  * @lines:		An array desired lines, specified by offset
  *			index for the associated GPIO device.
  * @num_lines:		The number of lines to request.
- * @data:		The array of values get from gpiochip.
+ * @values:		The array of values get from gpiochip.
  *
  * Return:		On success return 0;
  *			On failure return the errno.
  */
 int gpiotools_gets(const char *device_name, unsigned int *lines,
-		   unsigned int num_lines, struct gpiohandle_data *data)
+		   unsigned int num_lines, unsigned int *values)
 {
-	int fd;
+	int fd, i;
 	int ret;
 	int ret_close;
+	struct gpio_v2_line_config config;
+	struct gpio_v2_line_values lv;
 
-	ret = gpiotools_request_linehandle(device_name, lines, num_lines,
-					   GPIOHANDLE_REQUEST_INPUT, data,
-					   CONSUMER);
+	memset(&config, 0, sizeof(config));
+	config.flags = GPIO_V2_LINE_FLAG_INPUT;
+	ret = gpiotools_request_line(device_name, lines, num_lines,
+				     &config, CONSUMER);
 	if (ret < 0)
 		return ret;
 
 	fd = ret;
-	ret = gpiotools_get_values(fd, data);
-	ret_close = gpiotools_release_linehandle(fd);
+	for (i = 0; i < num_lines; i++)
+		gpiotools_set_bit(&lv.mask, i);
+	ret = gpiotools_get_values(fd, &lv);
+	if (!ret)
+		for (i = 0; i < num_lines; i++)
+			values[i] = gpiotools_test_bit(lv.bits, i);
+	ret_close = gpiotools_release_line(fd);
 	return ret < 0 ? ret : ret_close;
 }
 
@@ -232,11 +240,9 @@ int gpiotools_gets(const char *device_name, unsigned int *lines,
 int gpiotools_set(const char *device_name, unsigned int line,
 		  unsigned int value)
 {
-	struct gpiohandle_data data;
 	unsigned int lines[] = {line};
 
-	data.values[0] = value;
-	return gpiotools_sets(device_name, lines, 1, &data);
+	return gpiotools_sets(device_name, lines, 1, &value);
 }
 
 /**
@@ -246,22 +252,31 @@ int gpiotools_set(const char *device_name, unsigned int line,
  * @lines:		An array desired lines, specified by offset
  *			index for the associated GPIO device.
  * @num_lines:		The number of lines to request.
- * @data:		The array of values set to gpiochip, must be
+ * @value:		The array of values set to gpiochip, must be
  *			0(low) or 1(high).
  *
  * Return:		On success return 0;
  *			On failure return the errno.
  */
 int gpiotools_sets(const char *device_name, unsigned int *lines,
-		   unsigned int num_lines, struct gpiohandle_data *data)
+		   unsigned int num_lines, unsigned int *values)
 {
-	int ret;
+	int ret, i;
+	struct gpio_v2_line_config config;
 
-	ret = gpiotools_request_linehandle(device_name, lines, num_lines,
-					   GPIOHANDLE_REQUEST_OUTPUT, data,
-					   CONSUMER);
+	memset(&config, 0, sizeof(config));
+	config.flags = GPIO_V2_LINE_FLAG_OUTPUT;
+	config.num_attrs = 1;
+	config.attrs[0].attr.id = GPIO_V2_LINE_ATTR_ID_OUTPUT_VALUES;
+	for (i = 0; i < num_lines; i++) {
+		gpiotools_set_bit(&config.attrs[0].mask, i);
+		gpiotools_assign_bit(&config.attrs[0].attr.values,
+				     i, values[i]);
+	}
+	ret = gpiotools_request_line(device_name, lines, num_lines,
+				     &config, CONSUMER);
 	if (ret < 0)
 		return ret;
 
-	return gpiotools_release_linehandle(ret);
+	return gpiotools_release_line(ret);
 }
diff --git a/tools/gpio/gpio-utils.h b/tools/gpio/gpio-utils.h
index 324729577865..58c93a90add6 100644
--- a/tools/gpio/gpio-utils.h
+++ b/tools/gpio/gpio-utils.h
@@ -12,7 +12,9 @@
 #ifndef _GPIO_UTILS_H_
 #define _GPIO_UTILS_H_
 
+#include <stdbool.h>
 #include <string.h>
+#include <linux/types.h>
 
 #define ARRAY_SIZE(arr) (sizeof(arr) / sizeof((arr)[0]))
 
@@ -22,20 +24,50 @@ static inline int check_prefix(const char *str, const char *prefix)
 		strncmp(str, prefix, strlen(prefix)) == 0;
 }
 
-int gpiotools_request_linehandle(const char *device_name, unsigned int *lines,
-				 unsigned int num_lines, unsigned int flag,
-				 struct gpiohandle_data *data,
-				 const char *consumer_label);
-int gpiotools_set_values(const int fd, struct gpiohandle_data *data);
-int gpiotools_get_values(const int fd, struct gpiohandle_data *data);
-int gpiotools_release_linehandle(const int fd);
+int gpiotools_request_line(const char *device_name,
+			   unsigned int *lines,
+			   unsigned int num_lines,
+			   struct gpio_v2_line_config *config,
+			   const char *consumer);
+int gpiotools_set_values(const int fd, struct gpio_v2_line_values *values);
+int gpiotools_get_values(const int fd, struct gpio_v2_line_values *values);
+int gpiotools_release_line(const int fd);
 
 int gpiotools_get(const char *device_name, unsigned int line);
 int gpiotools_gets(const char *device_name, unsigned int *lines,
-		   unsigned int num_lines, struct gpiohandle_data *data);
+		   unsigned int num_lines, unsigned int *values);
 int gpiotools_set(const char *device_name, unsigned int line,
 		  unsigned int value);
 int gpiotools_sets(const char *device_name, unsigned int *lines,
-		   unsigned int num_lines, struct gpiohandle_data *data);
+		   unsigned int num_lines, unsigned int *values);
+
+/* helper functions for gpio_v2_line_values bits */
+static inline void gpiotools_set_bit(__u64 *b, int n)
+{
+	*b |= 1ULL << n;
+}
+
+static inline void gpiotools_change_bit(__u64 *b, int n)
+{
+	*b ^= 1ULL << n;
+}
+
+static inline void gpiotools_clear_bit(__u64 *b, int n)
+{
+	*b &= ~(1ULL << n);
+}
+
+static inline int gpiotools_test_bit(__u64 b, int n)
+{
+	return !!(b & 1ULL << n);
+}
+
+static inline void gpiotools_assign_bit(__u64 *b, int n, bool value)
+{
+	if (value)
+		gpiotools_set_bit(b, n);
+	else
+		gpiotools_clear_bit(b, n);
+}
 
 #endif /* _GPIO_UTILS_H_ */
-- 
2.28.0

[PATCH v4 18/20] tools: gpio: port gpio-event-mon to v2 uAPI

[Kent Gibson]

Port the gpio-event-mon tool to the latest GPIO uAPI.

Signed-off-by: Kent Gibson <warthog618@gmail.com>
---
 tools/gpio/gpio-event-mon.c | 91 +++++++++++++++++++------------------
 1 file changed, 47 insertions(+), 44 deletions(-)

diff --git a/tools/gpio/gpio-event-mon.c b/tools/gpio/gpio-event-mon.c
index 1a303a81aeef..d6a831200c18 100644
--- a/tools/gpio/gpio-event-mon.c
+++ b/tools/gpio/gpio-event-mon.c
@@ -23,17 +23,16 @@
 #include <sys/ioctl.h>
 #include <sys/types.h>
 #include <linux/gpio.h>
+#include "gpio-utils.h"
 
 int monitor_device(const char *device_name,
 		   unsigned int line,
-		   uint32_t handleflags,
-		   uint32_t eventflags,
+		   struct gpio_v2_line_config *config,
 		   unsigned int loops)
 {
-	struct gpioevent_request req;
-	struct gpiohandle_data data;
+	struct gpio_v2_line_values values;
 	char *chrdev_name;
-	int fd;
+	int cfd, lfd;
 	int ret;
 	int i = 0;
 
@@ -41,44 +40,39 @@ int monitor_device(const char *device_name,
 	if (ret < 0)
 		return -ENOMEM;
 
-	fd = open(chrdev_name, 0);
-	if (fd == -1) {
+	cfd = open(chrdev_name, 0);
+	if (cfd == -1) {
 		ret = -errno;
 		fprintf(stderr, "Failed to open %s\n", chrdev_name);
 		goto exit_free_name;
 	}
 
-	req.lineoffset = line;
-	req.handleflags = handleflags;
-	req.eventflags = eventflags;
-	strcpy(req.consumer_label, "gpio-event-mon");
-
-	ret = ioctl(fd, GPIO_GET_LINEEVENT_IOCTL, &req);
-	if (ret == -1) {
-		ret = -errno;
-		fprintf(stderr, "Failed to issue GET EVENT "
-			"IOCTL (%d)\n",
-			ret);
-		goto exit_close_error;
-	}
+	ret = gpiotools_request_line(device_name, &line, 1, config,
+				     "gpio-event-mon");
+	if (ret < 0)
+		goto exit_device_close;
+	else
+		lfd = ret;
 
 	/* Read initial states */
-	ret = ioctl(req.fd, GPIOHANDLE_GET_LINE_VALUES_IOCTL, &data);
-	if (ret == -1) {
-		ret = -errno;
-		fprintf(stderr, "Failed to issue GPIOHANDLE GET LINE "
-			"VALUES IOCTL (%d)\n",
+	values.mask = 1;
+	values.bits = 0;
+	ret = gpiotools_get_values(lfd, &values);
+	if (ret < 0) {
+		fprintf(stderr,
+			"Failed to issue GPIO LINE GET VALUES IOCTL (%d)\n",
 			ret);
-		goto exit_close_error;
+		goto exit_line_close;
 	}
 
 	fprintf(stdout, "Monitoring line %d on %s\n", line, device_name);
-	fprintf(stdout, "Initial line value: %d\n", data.values[0]);
+	fprintf(stdout, "Initial line value: %d\n",
+		gpiotools_test_bit(values.bits, 0));
 
 	while (1) {
-		struct gpioevent_data event;
+		struct gpio_v2_line_event event;
 
-		ret = read(req.fd, &event, sizeof(event));
+		ret = read(lfd, &event, sizeof(event));
 		if (ret == -1) {
 			if (errno == -EAGAIN) {
 				fprintf(stderr, "nothing available\n");
@@ -96,12 +90,14 @@ int monitor_device(const char *device_name,
 			ret = -EIO;
 			break;
 		}
-		fprintf(stdout, "GPIO EVENT %llu: ", event.timestamp);
+		fprintf(stdout, "GPIO EVENT at %llu on line %d (%d|%d) ",
+			event.timestamp, event.offset, event.line_seqno,
+			event.seqno);
 		switch (event.id) {
-		case GPIOEVENT_EVENT_RISING_EDGE:
+		case GPIO_V2_LINE_EVENT_RISING_EDGE:
 			fprintf(stdout, "rising edge");
 			break;
-		case GPIOEVENT_EVENT_FALLING_EDGE:
+		case GPIO_V2_LINE_EVENT_FALLING_EDGE:
 			fprintf(stdout, "falling edge");
 			break;
 		default:
@@ -114,8 +110,11 @@ int monitor_device(const char *device_name,
 			break;
 	}
 
-exit_close_error:
-	if (close(fd) == -1)
+exit_line_close:
+	if (close(lfd) == -1)
+		perror("Failed to close line file");
+exit_device_close:
+	if (close(cfd) == -1)
 		perror("Failed to close GPIO character device file");
 exit_free_name:
 	free(chrdev_name);
@@ -140,15 +139,20 @@ void print_usage(void)
 	);
 }
 
+#define EDGE_FLAGS \
+	(GPIO_V2_LINE_FLAG_EDGE_RISING | \
+	 GPIO_V2_LINE_FLAG_EDGE_FALLING)
+
 int main(int argc, char **argv)
 {
 	const char *device_name = NULL;
 	unsigned int line = -1;
 	unsigned int loops = 0;
-	uint32_t handleflags = GPIOHANDLE_REQUEST_INPUT;
-	uint32_t eventflags = 0;
+	struct gpio_v2_line_config config;
 	int c;
 
+	memset(&config, 0, sizeof(config));
+	config.flags = GPIO_V2_LINE_FLAG_INPUT;
 	while ((c = getopt(argc, argv, "c:n:o:dsrf?")) != -1) {
 		switch (c) {
 		case 'c':
@@ -161,16 +165,16 @@ int main(int argc, char **argv)
 			line = strtoul(optarg, NULL, 10);
 			break;
 		case 'd':
-			handleflags |= GPIOHANDLE_REQUEST_OPEN_DRAIN;
+			config.flags |= GPIO_V2_LINE_FLAG_OPEN_DRAIN;
 			break;
 		case 's':
-			handleflags |= GPIOHANDLE_REQUEST_OPEN_SOURCE;
+			config.flags |= GPIO_V2_LINE_FLAG_OPEN_SOURCE;
 			break;
 		case 'r':
-			eventflags |= GPIOEVENT_REQUEST_RISING_EDGE;
+			config.flags |= GPIO_V2_LINE_FLAG_EDGE_RISING;
 			break;
 		case 'f':
-			eventflags |= GPIOEVENT_REQUEST_FALLING_EDGE;
+			config.flags |= GPIO_V2_LINE_FLAG_EDGE_FALLING;
 			break;
 		case '?':
 			print_usage();
@@ -182,11 +186,10 @@ int main(int argc, char **argv)
 		print_usage();
 		return -1;
 	}
-	if (!eventflags) {
+	if (!(config.flags & EDGE_FLAGS)) {
 		printf("No flags specified, listening on both rising and "
 		       "falling edges\n");
-		eventflags = GPIOEVENT_REQUEST_BOTH_EDGES;
+		config.flags |= EDGE_FLAGS;
 	}
-	return monitor_device(device_name, line, handleflags,
-			      eventflags, loops);
+	return monitor_device(device_name, line, &config, loops);
 }
-- 
2.28.0

[PATCH v4 19/20] tools: gpio: add multi-line monitoring to gpio-event-mon

[Kent Gibson]

Extend gpio-event-mon to support monitoring multiple lines.
This would require multiple lineevent requests to implement using uAPI v1,
but can be performed with a single line request using uAPI v2.

Signed-off-by: Kent Gibson <warthog618@gmail.com>
---
 tools/gpio/gpio-event-mon.c | 45 ++++++++++++++++++++++++++++---------
 1 file changed, 34 insertions(+), 11 deletions(-)

diff --git a/tools/gpio/gpio-event-mon.c b/tools/gpio/gpio-event-mon.c
index d6a831200c18..e50bb107ea3a 100644
--- a/tools/gpio/gpio-event-mon.c
+++ b/tools/gpio/gpio-event-mon.c
@@ -26,7 +26,8 @@
 #include "gpio-utils.h"
 
 int monitor_device(const char *device_name,
-		   unsigned int line,
+		   unsigned int *lines,
+		   unsigned int num_lines,
 		   struct gpio_v2_line_config *config,
 		   unsigned int loops)
 {
@@ -47,7 +48,7 @@ int monitor_device(const char *device_name,
 		goto exit_free_name;
 	}
 
-	ret = gpiotools_request_line(device_name, &line, 1, config,
+	ret = gpiotools_request_line(device_name, lines, num_lines, config,
 				     "gpio-event-mon");
 	if (ret < 0)
 		goto exit_device_close;
@@ -55,8 +56,10 @@ int monitor_device(const char *device_name,
 		lfd = ret;
 
 	/* Read initial states */
-	values.mask = 1;
+	values.mask = 0;
 	values.bits = 0;
+	for (i = 0; i < num_lines; i++)
+		gpiotools_set_bit(&values.mask, i);
 	ret = gpiotools_get_values(lfd, &values);
 	if (ret < 0) {
 		fprintf(stderr,
@@ -65,9 +68,23 @@ int monitor_device(const char *device_name,
 		goto exit_line_close;
 	}
 
-	fprintf(stdout, "Monitoring line %d on %s\n", line, device_name);
-	fprintf(stdout, "Initial line value: %d\n",
-		gpiotools_test_bit(values.bits, 0));
+	if (num_lines == 1) {
+		fprintf(stdout, "Monitoring line %d on %s\n", lines[0], device_name);
+		fprintf(stdout, "Initial line value: %d\n",
+			gpiotools_test_bit(values.bits, 0));
+	} else {
+		fprintf(stdout, "Monitoring lines %d", lines[0]);
+		for (i = 1; i < num_lines - 1; i++)
+			fprintf(stdout, ", %d", lines[i]);
+		fprintf(stdout, " and %d on %s\n", lines[i], device_name);
+		fprintf(stdout, "Initial line values: %d",
+			gpiotools_test_bit(values.bits, 0));
+		for (i = 1; i < num_lines - 1; i++)
+			fprintf(stdout, ", %d",
+				gpiotools_test_bit(values.bits, i));
+		fprintf(stdout, " and %d\n",
+			gpiotools_test_bit(values.bits, i));
+	}
 
 	while (1) {
 		struct gpio_v2_line_event event;
@@ -126,7 +143,7 @@ void print_usage(void)
 	fprintf(stderr, "Usage: gpio-event-mon [options]...\n"
 		"Listen to events on GPIO lines, 0->1 1->0\n"
 		"  -n <name>  Listen on GPIOs on a named device (must be stated)\n"
-		"  -o <n>     Offset to monitor\n"
+		"  -o <n>     Offset of line to monitor (may be repeated)\n"
 		"  -d         Set line as open drain\n"
 		"  -s         Set line as open source\n"
 		"  -r         Listen for rising edges\n"
@@ -146,7 +163,8 @@ void print_usage(void)
 int main(int argc, char **argv)
 {
 	const char *device_name = NULL;
-	unsigned int line = -1;
+	unsigned int lines[GPIO_V2_LINES_MAX];
+	unsigned int num_lines = 0;
 	unsigned int loops = 0;
 	struct gpio_v2_line_config config;
 	int c;
@@ -162,7 +180,12 @@ int main(int argc, char **argv)
 			device_name = optarg;
 			break;
 		case 'o':
-			line = strtoul(optarg, NULL, 10);
+			if (num_lines >= GPIO_V2_LINES_MAX) {
+				print_usage();
+				return -1;
+			}
+			lines[num_lines] = strtoul(optarg, NULL, 10);
+			num_lines++;
 			break;
 		case 'd':
 			config.flags |= GPIO_V2_LINE_FLAG_OPEN_DRAIN;
@@ -182,7 +205,7 @@ int main(int argc, char **argv)
 		}
 	}
 
-	if (!device_name || line == -1) {
+	if (!device_name || num_lines == 0) {
 		print_usage();
 		return -1;
 	}
@@ -191,5 +214,5 @@ int main(int argc, char **argv)
 		       "falling edges\n");
 		config.flags |= EDGE_FLAGS;
 	}
-	return monitor_device(device_name, line, &config, loops);
+	return monitor_device(device_name, lines, num_lines, &config, loops);
 }
-- 
2.28.0

[PATCH v4 20/20] tools: gpio: add debounce support to gpio-event-mon

[Kent Gibson]

Add support for debouncing monitored lines to gpio-event-mon.

Signed-off-by: Kent Gibson <warthog618@gmail.com>
---
 tools/gpio/gpio-event-mon.c | 20 +++++++++++++++++---
 1 file changed, 17 insertions(+), 3 deletions(-)

diff --git a/tools/gpio/gpio-event-mon.c b/tools/gpio/gpio-event-mon.c
index e50bb107ea3a..bd5ea3cc6e85 100644
--- a/tools/gpio/gpio-event-mon.c
+++ b/tools/gpio/gpio-event-mon.c
@@ -148,11 +148,12 @@ void print_usage(void)
 		"  -s         Set line as open source\n"
 		"  -r         Listen for rising edges\n"
 		"  -f         Listen for falling edges\n"
+		"  -b <n>     Debounce the line with period n microseconds\n"
 		" [-c <n>]    Do <n> loops (optional, infinite loop if not stated)\n"
 		"  -?         This helptext\n"
 		"\n"
 		"Example:\n"
-		"gpio-event-mon -n gpiochip0 -o 4 -r -f\n"
+		"gpio-event-mon -n gpiochip0 -o 4 -r -f -b 10000\n"
 	);
 }
 
@@ -167,11 +168,12 @@ int main(int argc, char **argv)
 	unsigned int num_lines = 0;
 	unsigned int loops = 0;
 	struct gpio_v2_line_config config;
-	int c;
+	int c, attr, i;
+	unsigned long debounce_period = 0;
 
 	memset(&config, 0, sizeof(config));
 	config.flags = GPIO_V2_LINE_FLAG_INPUT;
-	while ((c = getopt(argc, argv, "c:n:o:dsrf?")) != -1) {
+	while ((c = getopt(argc, argv, "c:n:o:b:dsrf?")) != -1) {
 		switch (c) {
 		case 'c':
 			loops = strtoul(optarg, NULL, 10);
@@ -187,6 +189,9 @@ int main(int argc, char **argv)
 			lines[num_lines] = strtoul(optarg, NULL, 10);
 			num_lines++;
 			break;
+		case 'b':
+			debounce_period = strtoul(optarg, NULL, 10);
+			break;
 		case 'd':
 			config.flags |= GPIO_V2_LINE_FLAG_OPEN_DRAIN;
 			break;
@@ -205,6 +210,15 @@ int main(int argc, char **argv)
 		}
 	}
 
+	if (debounce_period) {
+		attr = config.num_attrs;
+		config.num_attrs++;
+		for (i = 0; i < num_lines; i++)
+			gpiotools_set_bit(&config.attrs[attr].mask, i);
+		config.attrs[attr].attr.id = GPIO_V2_LINE_ATTR_ID_DEBOUNCE;
+		config.attrs[attr].attr.debounce_period = debounce_period;
+	}
+
 	if (!device_name || num_lines == 0) {
 		print_usage();
 		return -1;
-- 
2.28.0

Re: [PATCH v4 07/20] gpiolib: cdev: support GPIO_V2_GET_LINE_IOCTL and GPIO_V2_LINE_GET_VALUES_IOCTL

[Bartosz Golaszewski]

On Fri, Aug 14, 2020 at 5:04 AM Kent Gibson <warthog618@gmail.com> wrote:
>
> Add support for requesting lines using the GPIO_V2_GET_LINE_IOCTL, and
> returning their current values using GPIO_V2_LINE_GET_VALUES_IOCTL.
>
> Signed-off-by: Kent Gibson <warthog618@gmail.com>
> ---

Hi Kent,

not many comments here, just a couple minor details below.

>
> The struct line implementation is based on the v1 struct linehandle
> implementation.
>
> The line_ioctl() is a simple wrapper around line_get_values() here, but
> will be extended with other ioctls in subsequent patches.
>
> Changes for v4:
>  - fix handling of mask in line_get_values
>
>  drivers/gpio/gpiolib-cdev.c | 413 ++++++++++++++++++++++++++++++++++++
>  1 file changed, 413 insertions(+)
>
> diff --git a/drivers/gpio/gpiolib-cdev.c b/drivers/gpio/gpiolib-cdev.c
> index 8b012879fe3f..8671e04ff989 100644
> --- a/drivers/gpio/gpiolib-cdev.c
> +++ b/drivers/gpio/gpiolib-cdev.c
> @@ -1,7 +1,9 @@
>  // SPDX-License-Identifier: GPL-2.0
>
>  #include <linux/anon_inodes.h>
> +#include <linux/atomic.h>
>  #include <linux/bitmap.h>
> +#include <linux/build_bug.h>
>  #include <linux/cdev.h>
>  #include <linux/compat.h>
>  #include <linux/device.h>
> @@ -34,6 +36,7 @@
>   * GPIO line handle management
>   */
>
> +#ifdef CONFIG_GPIO_CDEV_V1
>  /**
>   * struct linehandle_state - contains the state of a userspace handle
>   * @gdev: the GPIO device the handle pertains to
> @@ -376,6 +379,390 @@ static int linehandle_create(struct gpio_device *gdev, void __user *ip)
>         linehandle_free(lh);
>         return ret;
>  }
> +#endif /* CONFIG_GPIO_CDEV_V1 */
> +
> +/**
> + * struct line - contains the state of a userspace line request
> + * @gdev: the GPIO device the line request pertains to
> + * @label: consumer label used to tag descriptors
> + * @num_descs: the number of descriptors held in the descs array
> + * @descs: the GPIO descriptors held by this line request, with @num_descs
> + * elements.
> + */
> +struct line {

How about line_request, line_request_data or line_req_ctx? Something
more intuitive than struct line that doesn't even refer to a single
line. Same for relevant functions below.

> +       struct gpio_device *gdev;
> +       const char *label;
> +       u32 num_descs;
> +       struct gpio_desc *descs[];
> +};
> +
> +#define GPIO_V2_LINE_BIAS_FLAGS \
> +       (GPIO_V2_LINE_FLAG_BIAS_PULL_UP | \
> +        GPIO_V2_LINE_FLAG_BIAS_PULL_DOWN | \
> +        GPIO_V2_LINE_FLAG_BIAS_DISABLED)
> +
> +#define GPIO_V2_LINE_DIRECTION_FLAGS \
> +       (GPIO_V2_LINE_FLAG_INPUT | \
> +        GPIO_V2_LINE_FLAG_OUTPUT)
> +
> +#define GPIO_V2_LINE_DRIVE_FLAGS \
> +       (GPIO_V2_LINE_FLAG_OPEN_DRAIN | \
> +        GPIO_V2_LINE_FLAG_OPEN_SOURCE)
> +
> +#define GPIO_V2_LINE_VALID_FLAGS \
> +       (GPIO_V2_LINE_FLAG_ACTIVE_LOW | \
> +        GPIO_V2_LINE_DIRECTION_FLAGS | \
> +        GPIO_V2_LINE_DRIVE_FLAGS | \
> +        GPIO_V2_LINE_BIAS_FLAGS)
> +
> +static u64 gpio_v2_line_config_flags(struct gpio_v2_line_config *lc,
> +                                    int line_idx)
> +{
> +       int i;
> +       u64 mask = BIT_ULL(line_idx);
> +
> +       for (i = 0; i < lc->num_attrs; i++) {
> +               if ((lc->attrs[i].attr.id == GPIO_V2_LINE_ATTR_ID_FLAGS) &&
> +                   (lc->attrs[i].mask & mask))
> +                       return lc->attrs[i].attr.flags;
> +       }
> +       return lc->flags;
> +}
> +
> +static int gpio_v2_line_config_output_value(struct gpio_v2_line_config *lc,
> +                                           int line_idx)
> +{
> +       int i;
> +       u64 mask = BIT_ULL(line_idx);
> +
> +       for (i = 0; i < lc->num_attrs; i++) {
> +               if ((lc->attrs[i].attr.id == GPIO_V2_LINE_ATTR_ID_OUTPUT_VALUES) &&
> +                   (lc->attrs[i].mask & mask))
> +                       return !!(lc->attrs[i].attr.values & mask);
> +       }
> +       return 0;
> +}
> +
> +static int gpio_v2_line_flags_validate(u64 flags)
> +{
> +       /* Return an error if an unknown flag is set */
> +       if (flags & ~GPIO_V2_LINE_VALID_FLAGS)
> +               return -EINVAL;
> +
> +       /*
> +        * Do not allow both INPUT & OUTPUT flags to be set as they are
> +        * contradictory.
> +        */
> +       if ((flags & GPIO_V2_LINE_FLAG_INPUT) &&
> +           (flags & GPIO_V2_LINE_FLAG_OUTPUT))
> +               return -EINVAL;
> +
> +       /*
> +        * Do not allow OPEN_SOURCE & OPEN_DRAIN flags in a single request. If
> +        * the hardware actually supports enabling both at the same time the
> +        * electrical result would be disastrous.
> +        */
> +       if ((flags & GPIO_V2_LINE_FLAG_OPEN_DRAIN) &&
> +           (flags & GPIO_V2_LINE_FLAG_OPEN_SOURCE))
> +               return -EINVAL;
> +
> +       /* Drive requires explicit output direction. */
> +       if ((flags & GPIO_V2_LINE_DRIVE_FLAGS) &&
> +           !(flags & GPIO_V2_LINE_FLAG_OUTPUT))
> +               return -EINVAL;
> +
> +       /* Bias requies explicit direction. */

s/requies/requires/

> +       if ((flags & GPIO_V2_LINE_BIAS_FLAGS) &&
> +           !(flags & GPIO_V2_LINE_DIRECTION_FLAGS))
> +               return -EINVAL;
> +
> +       /* Only one bias flag can be set. */
> +       if (((flags & GPIO_V2_LINE_FLAG_BIAS_DISABLED) &&
> +            (flags & (GPIO_V2_LINE_FLAG_BIAS_PULL_DOWN |
> +                      GPIO_V2_LINE_FLAG_BIAS_PULL_UP))) ||
> +           ((flags & GPIO_V2_LINE_FLAG_BIAS_PULL_DOWN) &&
> +            (flags & GPIO_V2_LINE_FLAG_BIAS_PULL_UP)))
> +               return -EINVAL;
> +
> +       return 0;
> +}
> +
> +static int gpio_v2_line_config_validate(struct gpio_v2_line_config *lc,
> +                                       int num_lines)

I recall sending some patches for gpiolib that would fix some
potential problems with casting between signed and unsigned integers.
I think they were of different size too though. I don't see any
potential problems here yet but maybe whenever an argument/local
variable can't take a negative value by design, let's use unsigned
int?

> +{
> +       int i, ret;

Same here and elsewhere for arguments and local variables.

> +       u64 flags;
> +
> +       if (lc->num_attrs > GPIO_V2_LINE_NUM_ATTRS_MAX)
> +               return -EINVAL;
> +
> +       if (memchr_inv(lc->padding, 0, sizeof(lc->padding)))
> +               return -EINVAL;
> +
> +       for (i = 0; i < num_lines; i++) {
> +               flags = gpio_v2_line_config_flags(lc, i);
> +               ret = gpio_v2_line_flags_validate(flags);
> +               if (ret)
> +                       return ret;
> +       }
> +       return 0;
> +}
> +
> +static void gpio_v2_line_config_flags_to_desc_flags(u64 flags,
> +                                                   unsigned long *flagsp)
> +{
> +       assign_bit(FLAG_ACTIVE_LOW, flagsp,
> +                  flags & GPIO_V2_LINE_FLAG_ACTIVE_LOW);
> +       if (flags & GPIO_V2_LINE_FLAG_OUTPUT)
> +               set_bit(FLAG_IS_OUT, flagsp);
> +       else if (flags & GPIO_V2_LINE_FLAG_INPUT)
> +               clear_bit(FLAG_IS_OUT, flagsp);
> +       assign_bit(FLAG_OPEN_DRAIN, flagsp,
> +                  flags & GPIO_V2_LINE_FLAG_OPEN_DRAIN);
> +       assign_bit(FLAG_OPEN_SOURCE, flagsp,
> +                  flags & GPIO_V2_LINE_FLAG_OPEN_SOURCE);
> +       assign_bit(FLAG_PULL_UP, flagsp,
> +                  flags & GPIO_V2_LINE_FLAG_BIAS_PULL_UP);
> +       assign_bit(FLAG_PULL_DOWN, flagsp,
> +                  flags & GPIO_V2_LINE_FLAG_BIAS_PULL_DOWN);
> +       assign_bit(FLAG_BIAS_DISABLE, flagsp,
> +                  flags & GPIO_V2_LINE_FLAG_BIAS_DISABLED);
> +}
> +
> +static long line_get_values(struct line *line, void __user *ip)
> +{
> +       struct gpio_v2_line_values lv;
> +       DECLARE_BITMAP(vals, GPIO_V2_LINES_MAX);
> +       struct gpio_desc **descs;
> +       int ret, i, didx, num_get = 0;
> +
> +       /* NOTE: It's ok to read values of output lines. */
> +       if (copy_from_user(&lv, ip, sizeof(lv)))
> +               return -EFAULT;
> +
> +       if (lv.mask == 0)
> +               return -EINVAL;
> +
> +       for (i = 0; i < line->num_descs; i++)
> +               if (lv.mask & BIT_ULL(i))
> +                       num_get++;
> +       if (num_get == line->num_descs) {
> +               descs = line->descs;
> +       } else {
> +               descs = kmalloc_array(num_get, sizeof(*descs), GFP_KERNEL);
> +               for (didx = 0, i = 0; i < line->num_descs; i++) {
> +                       if (lv.mask & BIT_ULL(i)) {
> +                               descs[didx] = line->descs[i];
> +                               didx++;
> +                       }
> +               }
> +       }
> +       ret = gpiod_get_array_value_complex(false,
> +                                           true,
> +                                           num_get,
> +                                           descs,
> +                                           NULL,
> +                                           vals);
> +
> +       if (descs != line->descs)
> +               kfree(descs);
> +       if (ret)
> +               return ret;
> +
> +       lv.bits = 0;
> +       for (didx = 0, i = 0; i < line->num_descs; i++) {
> +               if (lv.mask & BIT_ULL(i)) {
> +                       if (test_bit(didx, vals))
> +                               lv.bits |= BIT_ULL(i);
> +                       didx++;
> +               }
> +       }
> +
> +       if (copy_to_user(ip, &lv, sizeof(lv)))
> +               return -EFAULT;
> +
> +       return 0;
> +}
> +
> +static long line_ioctl(struct file *file, unsigned int cmd,
> +                      unsigned long arg)
> +{
> +       struct line *line = file->private_data;
> +       void __user *ip = (void __user *)arg;
> +
> +       if (cmd == GPIO_V2_LINE_GET_VALUES_IOCTL)
> +               return line_get_values(line, ip);
> +
> +       return -EINVAL;
> +}
> +
> +#ifdef CONFIG_COMPAT
> +static long line_ioctl_compat(struct file *file, unsigned int cmd,
> +                             unsigned long arg)
> +{
> +       return line_ioctl(file, cmd, (unsigned long)compat_ptr(arg));
> +}
> +#endif
> +
> +static void line_free(struct line *line)
> +{
> +       int i;
> +
> +       for (i = 0; i < line->num_descs; i++) {
> +               if (line->descs[i])
> +                       gpiod_free(line->descs[i]);
> +       }
> +       kfree(line->label);
> +       put_device(&line->gdev->dev);
> +       kfree(line);
> +}
> +
> +static int line_release(struct inode *inode, struct file *file)
> +{
> +       struct line *line = file->private_data;
> +
> +       line_free(line);
> +       return 0;
> +}
> +
> +static const struct file_operations line_fileops = {
> +       .release = line_release,
> +       .owner = THIS_MODULE,
> +       .llseek = noop_llseek,
> +       .unlocked_ioctl = line_ioctl,
> +#ifdef CONFIG_COMPAT
> +       .compat_ioctl = line_ioctl_compat,
> +#endif
> +};
> +
> +static int line_create(struct gpio_device *gdev, void __user *ip)
> +{
> +       struct gpio_v2_line_request lr;
> +       struct line *line;
> +       struct file *file;
> +       int fd, i, ret;
> +       struct gpio_v2_line_config *lc;
> +       unsigned long flags;
> +
> +       if (copy_from_user(&lr, ip, sizeof(lr)))
> +               return -EFAULT;
> +       if ((lr.num_lines == 0) || (lr.num_lines > GPIO_V2_LINES_MAX))
> +               return -EINVAL;
> +
> +       if (memchr_inv(lr.padding, 0, sizeof(lr.padding)))
> +               return -EINVAL;
> +
> +       lc = &lr.config;
> +       ret = gpio_v2_line_config_validate(lc, lr.num_lines);
> +       if (ret)
> +               return ret;
> +
> +       line = kzalloc(struct_size(line, descs, lr.num_lines),
> +                      GFP_KERNEL);
> +       if (!line)
> +               return -ENOMEM;
> +
> +       line->gdev = gdev;
> +       get_device(&gdev->dev);
> +
> +       /* Make sure this is terminated */
> +       lr.consumer[sizeof(lr.consumer)-1] = '\0';
> +       if (strlen(lr.consumer)) {
> +               line->label = kstrdup(lr.consumer, GFP_KERNEL);
> +               if (!line->label) {
> +                       ret = -ENOMEM;
> +                       goto out_free_line;
> +               }
> +       }
> +
> +       line->num_descs = lr.num_lines;
> +
> +       /* Request each GPIO */
> +       for (i = 0; i < lr.num_lines; i++) {
> +               u32 offset = lr.offsets[i];
> +               struct gpio_desc *desc = gpiochip_get_desc(gdev->chip, offset);
> +
> +               if (IS_ERR(desc)) {
> +                       ret = PTR_ERR(desc);
> +                       goto out_free_line;
> +               }
> +
> +               ret = gpiod_request(desc, line->label);
> +               if (ret)
> +                       goto out_free_line;
> +
> +               line->descs[i] = desc;
> +               flags = gpio_v2_line_config_flags(lc, i);
> +               gpio_v2_line_config_flags_to_desc_flags(flags, &desc->flags);
> +
> +               ret = gpiod_set_transitory(desc, false);
> +               if (ret < 0)
> +                       goto out_free_line;
> +
> +               /*
> +                * Lines have to be requested explicitly for input
> +                * or output, else the line will be treated "as is".
> +                */
> +               if (flags & GPIO_V2_LINE_FLAG_OUTPUT) {
> +                       int val = gpio_v2_line_config_output_value(lc, i);
> +
> +                       ret = gpiod_direction_output(desc, val);
> +                       if (ret)
> +                               goto out_free_line;
> +               } else if (flags & GPIO_V2_LINE_FLAG_INPUT) {
> +                       ret = gpiod_direction_input(desc);
> +                       if (ret)
> +                               goto out_free_line;
> +               }
> +
> +               blocking_notifier_call_chain(&desc->gdev->notifier,
> +                                            GPIOLINE_CHANGED_REQUESTED, desc);
> +
> +               dev_dbg(&gdev->dev, "registered chardev handle for line %d\n",
> +                       offset);
> +       }
> +
> +       fd = get_unused_fd_flags(O_RDONLY | O_CLOEXEC);
> +       if (fd < 0) {
> +               ret = fd;
> +               goto out_free_line;
> +       }
> +
> +       file = anon_inode_getfile("gpio-line",
> +                                 &line_fileops,
> +                                 line,
> +                                 O_RDONLY | O_CLOEXEC);
> +       if (IS_ERR(file)) {
> +               ret = PTR_ERR(file);
> +               goto out_put_unused_fd;
> +       }
> +
> +       lr.fd = fd;
> +       if (copy_to_user(ip, &lr, sizeof(lr))) {
> +               /*
> +                * fput() will trigger the release() callback, so do not go onto
> +                * the regular error cleanup path here.
> +                */
> +               fput(file);
> +               put_unused_fd(fd);
> +               return -EFAULT;
> +       }
> +
> +       fd_install(fd, file);
> +
> +       dev_dbg(&gdev->dev, "registered chardev handle for %d lines\n",
> +               line->num_descs);
> +
> +       return 0;
> +
> +out_put_unused_fd:
> +       put_unused_fd(fd);
> +out_free_line:
> +       line_free(line);
> +       return ret;
> +}
> +
> +#ifdef CONFIG_GPIO_CDEV_V1
>
>  /*
>   * GPIO line event management
> @@ -745,6 +1132,8 @@ static int lineevent_create(struct gpio_device *gdev, void __user *ip)
>         return ret;
>  }
>
> +#endif /* CONFIG_GPIO_CDEV_V1 */
> +
>  static void gpio_desc_to_lineinfo(struct gpio_desc *desc,
>                                   struct gpioline_info *info)
>  {
> @@ -842,6 +1231,7 @@ static long gpio_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
>                 if (copy_to_user(ip, &chipinfo, sizeof(chipinfo)))
>                         return -EFAULT;
>                 return 0;
> +#ifdef CONFIG_GPIO_CDEV_V1
>         } else if (cmd == GPIO_GET_LINEINFO_IOCTL) {
>                 struct gpioline_info lineinfo;
>
> @@ -884,6 +1274,9 @@ static long gpio_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
>                 }
>
>                 return 0;
> +#endif /* CONFIG_GPIO_CDEV_V1 */
> +       } else if (cmd == GPIO_V2_GET_LINE_IOCTL) {
> +               return line_create(gdev, ip);
>         } else if (cmd == GPIO_GET_LINEINFO_UNWATCH_IOCTL) {
>                 if (copy_from_user(&offset, ip, sizeof(offset)))
>                         return -EFAULT;
> @@ -1109,4 +1502,24 @@ int gpiolib_cdev_register(struct gpio_device *gdev, dev_t devt)
>  void gpiolib_cdev_unregister(struct gpio_device *gdev)
>  {
>         cdev_device_del(&gdev->chrdev, &gdev->dev);
> +
> +       /*
> +        * array sizes must ensure 64-bit alignment and not create holes in
> +        * the struct packing.
> +        */
> +       BUILD_BUG_ON(GPIO_V2_LINES_MAX % 2);
> +       BUILD_BUG_ON(GPIO_MAX_NAME_SIZE % 8);
> +
> +       /*
> +        * check that uAPI structs are 64-bit aligned for 32/64-bit
> +        * compatibility
> +        */
> +       BUILD_BUG_ON(sizeof(struct gpio_v2_line_attribute) % 8);
> +       BUILD_BUG_ON(sizeof(struct gpio_v2_line_config_attribute) % 8);
> +       BUILD_BUG_ON(sizeof(struct gpio_v2_line_config) % 8);
> +       BUILD_BUG_ON(sizeof(struct gpio_v2_line_request) % 8);
> +       BUILD_BUG_ON(sizeof(struct gpio_v2_line_info) % 8);
> +       BUILD_BUG_ON(sizeof(struct gpio_v2_line_info_changed) % 8);
> +       BUILD_BUG_ON(sizeof(struct gpio_v2_line_event) % 8);
> +       BUILD_BUG_ON(sizeof(struct gpio_v2_line_values) % 8);

You can use IS_ALIGNED() within BUILD_BUG_ON() for these checks and
I'd also put them somewhere else than the unregister function. Maybe
move it over to cdev_register() so that they're more visible?

>  }
> --
> 2.28.0
>

Bart

Re: [PATCH v4 07/20] gpiolib: cdev: support GPIO_V2_GET_LINE_IOCTL and GPIO_V2_LINE_GET_VALUES_IOCTL

[Kent Gibson]

On Fri, Aug 14, 2020 at 09:31:29PM +0200, Bartosz Golaszewski wrote:
> On Fri, Aug 14, 2020 at 5:04 AM Kent Gibson <warthog618@gmail.com> wrote:
> >
> > Add support for requesting lines using the GPIO_V2_GET_LINE_IOCTL, and
> > returning their current values using GPIO_V2_LINE_GET_VALUES_IOCTL.
> >
> > Signed-off-by: Kent Gibson <warthog618@gmail.com>
> > ---
> 
> Hi Kent,
> 
> not many comments here, just a couple minor details below.
> 

[snip]

> > +
> > +/**
> > + * struct line - contains the state of a userspace line request
> > + * @gdev: the GPIO device the line request pertains to
> > + * @label: consumer label used to tag descriptors
> > + * @num_descs: the number of descriptors held in the descs array
> > + * @descs: the GPIO descriptors held by this line request, with @num_descs
> > + * elements.
> > + */
> > +struct line {
> 
> How about line_request, line_request_data or line_req_ctx? Something
> more intuitive than struct line that doesn't even refer to a single
> line. Same for relevant functions below.
> 

As I've mentioned previously, I'm not a fan of names that include _data,
_ctx, _state, or similar that don't really add anything.

I did consider line_request, but that was too close to the
gpio_v2_line_request in gpio.d, not just the struct but also the
resulting local variables, particularly in line_create() where they
co-exist.

Given the ioctl names, GPIO_V2_GET_LINE_IOCTL and
GPIO_V2_LINE_GET/SET_xxx, that all create or operate on this struct, and
that this is within the scope of gpiolib-cdev, the name 'line' seemed the
best fit.

And how does it not refer to a single line - what are the descs??

No problems with your other comments.

Cheers,
Kent.

Re: [PATCH v4 07/20] gpiolib: cdev: support GPIO_V2_GET_LINE_IOCTL and GPIO_V2_LINE_GET_VALUES_IOCTL

[Bartosz Golaszewski]

On Sat, Aug 15, 2020 at 8:53 AM Kent Gibson <warthog618@gmail.com> wrote:
>
> On Fri, Aug 14, 2020 at 09:31:29PM +0200, Bartosz Golaszewski wrote:
> > On Fri, Aug 14, 2020 at 5:04 AM Kent Gibson <warthog618@gmail.com> wrote:
> > >
> > > Add support for requesting lines using the GPIO_V2_GET_LINE_IOCTL, and
> > > returning their current values using GPIO_V2_LINE_GET_VALUES_IOCTL.
> > >
> > > Signed-off-by: Kent Gibson <warthog618@gmail.com>
> > > ---
> >
> > Hi Kent,
> >
> > not many comments here, just a couple minor details below.
> >
>
> [snip]
>
> > > +
> > > +/**
> > > + * struct line - contains the state of a userspace line request
> > > + * @gdev: the GPIO device the line request pertains to
> > > + * @label: consumer label used to tag descriptors
> > > + * @num_descs: the number of descriptors held in the descs array
> > > + * @descs: the GPIO descriptors held by this line request, with @num_descs
> > > + * elements.
> > > + */
> > > +struct line {
> >
> > How about line_request, line_request_data or line_req_ctx? Something
> > more intuitive than struct line that doesn't even refer to a single
> > line. Same for relevant functions below.
> >
>
> As I've mentioned previously, I'm not a fan of names that include _data,
> _ctx, _state, or similar that don't really add anything.
>

I certainly disagree with you on this. I think it's useful to discern
the object itself from data associated with it. Let's consider struct
irq_data and let's imagine it would be called struct irq instead. The
latter would be misleading - as this struct contains a lot additional
fields that form the context for the irq but aren't logically part of
the "irq object". And then you have irq_common_data which is even more
disconnected from the irq. This also would make using the name "irq"
for the variables containing the global irq number confusing.

I think the same happens here: we may want to use the name "line" for
local variables and then having "struct line_data" (or similar) would
make it easier to read.

I'll listen to other's suggestions/voices but personally I think that
_ctx, _data etc. suffixes actually make sense.

> I did consider line_request, but that was too close to the
> gpio_v2_line_request in gpio.d, not just the struct but also the
> resulting local variables, particularly in line_create() where they
> co-exist.
>
> Given the ioctl names, GPIO_V2_GET_LINE_IOCTL and
> GPIO_V2_LINE_GET/SET_xxx, that all create or operate on this struct, and
> that this is within the scope of gpiolib-cdev, the name 'line' seemed the
> best fit.
>

And that's why line_data or line_request_data do make sense IMO.

> And how does it not refer to a single line - what are the descs??
>

I meant the fact that it can refer to multiple lines while being
called "struct line". I do find this misleading.

Bart

> No problems with your other comments.
>
> Cheers,
> Kent.
>

Re: [PATCH v4 07/20] gpiolib: cdev: support GPIO_V2_GET_LINE_IOCTL and GPIO_V2_LINE_GET_VALUES_IOCTL

[Kent Gibson]

On Sat, Aug 15, 2020 at 09:21:22AM +0200, Bartosz Golaszewski wrote:
> On Sat, Aug 15, 2020 at 8:53 AM Kent Gibson <warthog618@gmail.com> wrote:
> >
> > On Fri, Aug 14, 2020 at 09:31:29PM +0200, Bartosz Golaszewski wrote:
> > > On Fri, Aug 14, 2020 at 5:04 AM Kent Gibson <warthog618@gmail.com> wrote:
> > > >
> > > > Add support for requesting lines using the GPIO_V2_GET_LINE_IOCTL, and
> > > > returning their current values using GPIO_V2_LINE_GET_VALUES_IOCTL.
> > > >
> > > > Signed-off-by: Kent Gibson <warthog618@gmail.com>
> > > > ---
> > >
> > > Hi Kent,
> > >
> > > not many comments here, just a couple minor details below.
> > >
> >
> > [snip]
> >
> > > > +
> > > > +/**
> > > > + * struct line - contains the state of a userspace line request
> > > > + * @gdev: the GPIO device the line request pertains to
> > > > + * @label: consumer label used to tag descriptors
> > > > + * @num_descs: the number of descriptors held in the descs array
> > > > + * @descs: the GPIO descriptors held by this line request, with @num_descs
> > > > + * elements.
> > > > + */
> > > > +struct line {
> > >
> > > How about line_request, line_request_data or line_req_ctx? Something
> > > more intuitive than struct line that doesn't even refer to a single
> > > line. Same for relevant functions below.
> > >
> >
> > As I've mentioned previously, I'm not a fan of names that include _data,
> > _ctx, _state, or similar that don't really add anything.
> >
> 
> I certainly disagree with you on this. I think it's useful to discern
> the object itself from data associated with it. Let's consider struct
> irq_data and let's imagine it would be called struct irq instead. The
> latter would be misleading - as this struct contains a lot additional
> fields that form the context for the irq but aren't logically part of
> the "irq object". And then you have irq_common_data which is even more
> disconnected from the irq. This also would make using the name "irq"
> for the variables containing the global irq number confusing.
> 
> I think the same happens here: we may want to use the name "line" for
> local variables and then having "struct line_data" (or similar) would
> make it easier to read.
> 

My counter example to both points is "struct file *file".

> I'll listen to other's suggestions/voices but personally I think that
> _ctx, _data etc. suffixes actually make sense.
> 
> > I did consider line_request, but that was too close to the
> > gpio_v2_line_request in gpio.d, not just the struct but also the
> > resulting local variables, particularly in line_create() where they
> > co-exist.
> >
> > Given the ioctl names, GPIO_V2_GET_LINE_IOCTL and
> > GPIO_V2_LINE_GET/SET_xxx, that all create or operate on this struct, and
> > that this is within the scope of gpiolib-cdev, the name 'line' seemed the
> > best fit.
> >
> 
> And that's why line_data or line_request_data do make sense IMO.
> 
> > And how does it not refer to a single line - what are the descs??
> >
> 
> I meant the fact that it can refer to multiple lines while being
> called "struct line". I do find this misleading.
> 

And struct line_data isn't?

Cheers,
Kent.

Re: [PATCH v4 08/20] gpiolib: cdev: support GPIO_V2_GET_LINEINFO_IOCTL and GPIO_V2_GET_LINEINFO_WATCH_IOCTL

[Bartosz Golaszewski]

On Fri, Aug 14, 2020 at 5:04 AM Kent Gibson <warthog618@gmail.com> wrote:
>
> Add support for GPIO_V2_GET_LINEINFO_IOCTL and
> GPIO_V2_GET_LINEINFO_WATCH_IOCTL.
>
> Signed-off-by: Kent Gibson <warthog618@gmail.com>
> ---
>
> The core of this change is the event kfifo switching to contain
> struct gpioline_info_changed_v2, instead of v1 as v2 is richer.
>
> The two uAPI versions are mostly independent - other than where they both
> provide line info changes via reads on the chip fd.  As the info change
> structs differ between v1 and v2, the infowatch implementation tracks which
> version of the infowatch ioctl, either GPIO_GET_LINEINFO_WATCH_IOCTL or
> GPIO_V2_GET_LINEINFO_WATCH_IOCTL, initiates the initial watch and returns
> the corresponding info change struct to the read.  The version supported
> on that fd locks to that version on the first watch request, so subsequent
> watches from that process must use the same uAPI version.
>
> Changes for v4:
>  - replace strncpy with memcpy in gpio_v2_line_info_to_v1
>
>  drivers/gpio/gpiolib-cdev.c | 194 +++++++++++++++++++++++++++++++-----
>  1 file changed, 167 insertions(+), 27 deletions(-)
>
> diff --git a/drivers/gpio/gpiolib-cdev.c b/drivers/gpio/gpiolib-cdev.c
> index 8671e04ff989..28273f3105d3 100644
> --- a/drivers/gpio/gpiolib-cdev.c
> +++ b/drivers/gpio/gpiolib-cdev.c
> @@ -162,7 +162,8 @@ static long linehandle_set_config(struct linehandle_state *lh,
>                 }
>
>                 blocking_notifier_call_chain(&desc->gdev->notifier,
> -                                            GPIOLINE_CHANGED_CONFIG, desc);
> +                                            GPIO_V2_LINE_CHANGED_CONFIG,
> +                                            desc);
>         }
>         return 0;
>  }
> @@ -334,7 +335,7 @@ static int linehandle_create(struct gpio_device *gdev, void __user *ip)
>                 }
>
>                 blocking_notifier_call_chain(&desc->gdev->notifier,
> -                                            GPIOLINE_CHANGED_REQUESTED, desc);
> +                                            GPIO_V2_LINE_CHANGED_REQUESTED, desc);
>
>                 dev_dbg(&gdev->dev, "registered chardev handle for line %d\n",
>                         offset);
> @@ -716,7 +717,7 @@ static int line_create(struct gpio_device *gdev, void __user *ip)
>                 }
>
>                 blocking_notifier_call_chain(&desc->gdev->notifier,
> -                                            GPIOLINE_CHANGED_REQUESTED, desc);
> +                                            GPIO_V2_LINE_CHANGED_REQUESTED, desc);
>
>                 dev_dbg(&gdev->dev, "registered chardev handle for line %d\n",
>                         offset);
> @@ -1065,7 +1066,7 @@ static int lineevent_create(struct gpio_device *gdev, void __user *ip)
>                 goto out_free_le;
>
>         blocking_notifier_call_chain(&desc->gdev->notifier,
> -                                    GPIOLINE_CHANGED_REQUESTED, desc);
> +                                    GPIO_V2_LINE_CHANGED_REQUESTED, desc);
>
>         irq = gpiod_to_irq(desc);
>         if (irq <= 0) {
> @@ -1132,17 +1133,59 @@ static int lineevent_create(struct gpio_device *gdev, void __user *ip)
>         return ret;
>  }
>
> +static void gpio_v2_line_info_to_v1(struct gpio_v2_line_info *info_v2,
> +                                   struct gpioline_info *info_v1)
> +{
> +       int flagsv2 = info_v2->flags;
> +
> +       memcpy(info_v1->name, info_v2->name, sizeof(info_v1->name));
> +       memcpy(info_v1->consumer, info_v2->consumer,
> +              sizeof(info_v1->consumer));
> +       info_v1->line_offset = info_v2->offset;
> +       info_v1->flags = 0;
> +
> +       if (flagsv2 & GPIO_V2_LINE_FLAG_USED)
> +               info_v1->flags |= GPIOLINE_FLAG_KERNEL;
> +
> +       if (flagsv2 & GPIO_V2_LINE_FLAG_OUTPUT)
> +               info_v1->flags |= GPIOLINE_FLAG_IS_OUT;
> +
> +       if (flagsv2 & GPIO_V2_LINE_FLAG_ACTIVE_LOW)
> +               info_v1->flags |= GPIOLINE_FLAG_ACTIVE_LOW;
> +
> +       if (flagsv2 & GPIO_V2_LINE_FLAG_OPEN_DRAIN)
> +               info_v1->flags |= GPIOLINE_FLAG_OPEN_DRAIN;
> +       if (flagsv2 & GPIO_V2_LINE_FLAG_OPEN_SOURCE)
> +               info_v1->flags |= GPIOLINE_FLAG_OPEN_SOURCE;
> +
> +       if (flagsv2 & GPIO_V2_LINE_FLAG_BIAS_PULL_UP)
> +               info_v1->flags |= GPIOLINE_FLAG_BIAS_PULL_UP;
> +       if (flagsv2 & GPIO_V2_LINE_FLAG_BIAS_PULL_DOWN)
> +               info_v1->flags |= GPIOLINE_FLAG_BIAS_PULL_DOWN;
> +       if (flagsv2 & GPIO_V2_LINE_FLAG_BIAS_DISABLED)
> +               info_v1->flags |= GPIOLINE_FLAG_BIAS_DISABLE;
> +}
> +
> +static void gpio_v2_line_info_changed_to_v1(
> +               struct gpio_v2_line_info_changed *lic_v2,
> +               struct gpioline_info_changed *lic_v1)
> +{
> +       gpio_v2_line_info_to_v1(&lic_v2->info, &lic_v1->info);
> +       lic_v1->timestamp = lic_v2->timestamp;
> +       lic_v1->event_type = lic_v2->event_type;
> +}
> +
>  #endif /* CONFIG_GPIO_CDEV_V1 */
>
>  static void gpio_desc_to_lineinfo(struct gpio_desc *desc,
> -                                 struct gpioline_info *info)
> +                                 struct gpio_v2_line_info *info)
>  {
>         struct gpio_chip *gc = desc->gdev->chip;
>         bool ok_for_pinctrl;
>         unsigned long flags;
>
>         memset(info, 0, sizeof(*info));
> -       info->line_offset = gpio_chip_hwgpio(desc);
> +       info->offset = gpio_chip_hwgpio(desc);
>         /*
>          * This function takes a mutex so we must check this before taking
>          * the spinlock.
> @@ -1151,7 +1194,7 @@ static void gpio_desc_to_lineinfo(struct gpio_desc *desc,
>          * lock common to both frameworks?
>          */
>         ok_for_pinctrl =
> -               pinctrl_gpio_can_use_line(gc->base + info->line_offset);
> +               pinctrl_gpio_can_use_line(gc->base + info->offset);
>
>         spin_lock_irqsave(&gpio_lock, flags);
>
> @@ -1172,23 +1215,27 @@ static void gpio_desc_to_lineinfo(struct gpio_desc *desc,
>             test_bit(FLAG_EXPORT, &desc->flags) ||
>             test_bit(FLAG_SYSFS, &desc->flags) ||
>             !ok_for_pinctrl)
> -               info->flags |= GPIOLINE_FLAG_KERNEL;
> +               info->flags |= GPIO_V2_LINE_FLAG_USED;
> +
>         if (test_bit(FLAG_IS_OUT, &desc->flags))
> -               info->flags |= GPIOLINE_FLAG_IS_OUT;
> +               info->flags |= GPIO_V2_LINE_FLAG_OUTPUT;
> +       else
> +               info->flags |= GPIO_V2_LINE_FLAG_INPUT;
> +
>         if (test_bit(FLAG_ACTIVE_LOW, &desc->flags))
> -               info->flags |= GPIOLINE_FLAG_ACTIVE_LOW;
> +               info->flags |= GPIO_V2_LINE_FLAG_ACTIVE_LOW;
> +
>         if (test_bit(FLAG_OPEN_DRAIN, &desc->flags))
> -               info->flags |= (GPIOLINE_FLAG_OPEN_DRAIN |
> -                               GPIOLINE_FLAG_IS_OUT);
> +               info->flags |= GPIO_V2_LINE_FLAG_OPEN_DRAIN;
>         if (test_bit(FLAG_OPEN_SOURCE, &desc->flags))
> -               info->flags |= (GPIOLINE_FLAG_OPEN_SOURCE |
> -                               GPIOLINE_FLAG_IS_OUT);
> +               info->flags |= GPIO_V2_LINE_FLAG_OPEN_SOURCE;
> +
>         if (test_bit(FLAG_BIAS_DISABLE, &desc->flags))
> -               info->flags |= GPIOLINE_FLAG_BIAS_DISABLE;
> +               info->flags |= GPIO_V2_LINE_FLAG_BIAS_DISABLED;
>         if (test_bit(FLAG_PULL_DOWN, &desc->flags))
> -               info->flags |= GPIOLINE_FLAG_BIAS_PULL_DOWN;
> +               info->flags |= GPIO_V2_LINE_FLAG_BIAS_PULL_DOWN;
>         if (test_bit(FLAG_PULL_UP, &desc->flags))
> -               info->flags |= GPIOLINE_FLAG_BIAS_PULL_UP;
> +               info->flags |= GPIO_V2_LINE_FLAG_BIAS_PULL_UP;
>
>         spin_unlock_irqrestore(&gpio_lock, flags);
>  }
> @@ -1196,11 +1243,65 @@ static void gpio_desc_to_lineinfo(struct gpio_desc *desc,
>  struct gpio_chardev_data {
>         struct gpio_device *gdev;
>         wait_queue_head_t wait;
> -       DECLARE_KFIFO(events, struct gpioline_info_changed, 32);
> +       DECLARE_KFIFO(events, struct gpio_v2_line_info_changed, 32);
>         struct notifier_block lineinfo_changed_nb;
>         unsigned long *watched_lines;
> +#ifdef CONFIG_GPIO_CDEV_V1
> +       atomic_t watch_abi_version;
> +#endif
>  };
>
> +#ifdef CONFIG_GPIO_CDEV_V1
> +static int lineinfo_ensure_abi_version(struct gpio_chardev_data *cdata,
> +                                      unsigned int version)
> +{
> +       int abiv = atomic_read(&cdata->watch_abi_version);
> +
> +       if (abiv == 0) {
> +               atomic_cmpxchg(&cdata->watch_abi_version, 0, version);
> +               abiv = atomic_read(&cdata->watch_abi_version);
> +       }
> +       if (abiv != version)
> +               return -EPERM;
> +       return 0;
> +}
> +#endif
> +
> +static int lineinfo_get(struct gpio_chardev_data *cdev, void __user *ip,
> +                       unsigned int cmd)

I don't have many comments on this patch, it looks good. I'd only
prefer that the cmd argument be converted to 'bool watch' because this
is the only information we need here.

> +{
> +       struct gpio_desc *desc;
> +       struct gpio_v2_line_info lineinfo;
> +
> +       if (copy_from_user(&lineinfo, ip, sizeof(lineinfo)))
> +               return -EFAULT;
> +
> +       if (memchr_inv(lineinfo.padding, 0, sizeof(lineinfo.padding)))
> +               return -EINVAL;
> +
> +       desc = gpiochip_get_desc(cdev->gdev->chip, lineinfo.offset);
> +       if (IS_ERR(desc))
> +               return PTR_ERR(desc);
> +
> +       if (cmd == GPIO_V2_GET_LINEINFO_WATCH_IOCTL) {
> +#ifdef CONFIG_GPIO_CDEV_V1
> +               if (lineinfo_ensure_abi_version(cdev, 2))
> +                       return -EPERM;
> +#endif
> +               if (test_and_set_bit(lineinfo.offset, cdev->watched_lines))
> +                       return -EBUSY;
> +       }
> +       gpio_desc_to_lineinfo(desc, &lineinfo);
> +
> +       if (copy_to_user(ip, &lineinfo, sizeof(lineinfo))) {
> +               if (cmd == GPIO_V2_GET_LINEINFO_WATCH_IOCTL)
> +                       clear_bit(lineinfo.offset, cdev->watched_lines);
> +               return -EFAULT;
> +       }
> +
> +       return 0;
> +}
> +
>  /*
>   * gpio_ioctl() - ioctl handler for the GPIO chardev
>   */
> @@ -1210,7 +1311,6 @@ static long gpio_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
>         struct gpio_device *gdev = cdev->gdev;
>         struct gpio_chip *gc = gdev->chip;
>         void __user *ip = (void __user *)arg;
> -       struct gpio_desc *desc;
>         __u32 offset;
>
>         /* We fail any subsequent ioctl():s when the chip is gone */
> @@ -1233,7 +1333,9 @@ static long gpio_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
>                 return 0;
>  #ifdef CONFIG_GPIO_CDEV_V1
>         } else if (cmd == GPIO_GET_LINEINFO_IOCTL) {
> +               struct gpio_desc *desc;
>                 struct gpioline_info lineinfo;
> +               struct gpio_v2_line_info lineinfo_v2;
>
>                 if (copy_from_user(&lineinfo, ip, sizeof(lineinfo)))
>                         return -EFAULT;
> @@ -1243,7 +1345,8 @@ static long gpio_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
>                 if (IS_ERR(desc))
>                         return PTR_ERR(desc);
>
> -               gpio_desc_to_lineinfo(desc, &lineinfo);
> +               gpio_desc_to_lineinfo(desc, &lineinfo_v2);
> +               gpio_v2_line_info_to_v1(&lineinfo_v2, &lineinfo);
>
>                 if (copy_to_user(ip, &lineinfo, sizeof(lineinfo)))
>                         return -EFAULT;
> @@ -1253,7 +1356,9 @@ static long gpio_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
>         } else if (cmd == GPIO_GET_LINEEVENT_IOCTL) {
>                 return lineevent_create(gdev, ip);
>         } else if (cmd == GPIO_GET_LINEINFO_WATCH_IOCTL) {
> +               struct gpio_desc *desc;
>                 struct gpioline_info lineinfo;
> +               struct gpio_v2_line_info lineinfo_v2;
>
>                 if (copy_from_user(&lineinfo, ip, sizeof(lineinfo)))
>                         return -EFAULT;
> @@ -1263,10 +1368,14 @@ static long gpio_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
>                 if (IS_ERR(desc))
>                         return PTR_ERR(desc);
>
> +               if (lineinfo_ensure_abi_version(cdev, 1))
> +                       return -EPERM;
> +
>                 if (test_and_set_bit(lineinfo.line_offset, cdev->watched_lines))
>                         return -EBUSY;
>
> -               gpio_desc_to_lineinfo(desc, &lineinfo);
> +               gpio_desc_to_lineinfo(desc, &lineinfo_v2);
> +               gpio_v2_line_info_to_v1(&lineinfo_v2, &lineinfo);
>
>                 if (copy_to_user(ip, &lineinfo, sizeof(lineinfo))) {
>                         clear_bit(lineinfo.line_offset, cdev->watched_lines);
> @@ -1275,6 +1384,9 @@ static long gpio_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
>
>                 return 0;
>  #endif /* CONFIG_GPIO_CDEV_V1 */
> +       } else if (cmd == GPIO_V2_GET_LINEINFO_IOCTL ||
> +                  cmd == GPIO_V2_GET_LINEINFO_WATCH_IOCTL) {
> +               return lineinfo_get(cdev, ip, cmd);

... and then here it could be return lineinfo_get(cdev, ip, cmd ==
GPIO_V2_GET_LINEINFO_WATCH_IOCTL);

>         } else if (cmd == GPIO_V2_GET_LINE_IOCTL) {
>                 return line_create(gdev, ip);
>         } else if (cmd == GPIO_GET_LINEINFO_UNWATCH_IOCTL) {
> @@ -1310,7 +1422,7 @@ static int lineinfo_changed_notify(struct notifier_block *nb,
>                                    unsigned long action, void *data)
>  {
>         struct gpio_chardev_data *cdev = to_gpio_chardev_data(nb);
> -       struct gpioline_info_changed chg;
> +       struct gpio_v2_line_info_changed chg;
>         struct gpio_desc *desc = data;
>         int ret;
>
> @@ -1350,12 +1462,16 @@ static ssize_t lineinfo_watch_read(struct file *file, char __user *buf,
>                                    size_t count, loff_t *off)
>  {
>         struct gpio_chardev_data *cdev = file->private_data;
> -       struct gpioline_info_changed event;
> +       struct gpio_v2_line_info_changed event;
>         ssize_t bytes_read = 0;
>         int ret;
> +       size_t event_size;
>
> -       if (count < sizeof(event))
> +#ifndef CONFIG_GPIO_CDEV_V1
> +       event_size = sizeof(struct gpio_v2_line_info_changed);
> +       if (count < event_size)
>                 return -EINVAL;
> +#endif
>
>         do {
>                 spin_lock(&cdev->wait.lock);
> @@ -1377,7 +1493,17 @@ static ssize_t lineinfo_watch_read(struct file *file, char __user *buf,
>                                 return ret;
>                         }
>                 }
> -
> +#ifdef CONFIG_GPIO_CDEV_V1
> +               /* must be after kfifo check so watch_abi_version is set */
> +               if (atomic_read(&cdev->watch_abi_version) == 2)
> +                       event_size = sizeof(struct gpio_v2_line_info_changed);
> +               else
> +                       event_size = sizeof(struct gpioline_info_changed);
> +               if (count < event_size) {
> +                       spin_unlock(&cdev->wait.lock);
> +                       return -EINVAL;
> +               }
> +#endif
>                 ret = kfifo_out(&cdev->events, &event, 1);
>                 spin_unlock(&cdev->wait.lock);
>                 if (ret != 1) {
> @@ -1386,9 +1512,23 @@ static ssize_t lineinfo_watch_read(struct file *file, char __user *buf,
>                         /* We should never get here. See lineevent_read(). */
>                 }
>
> -               if (copy_to_user(buf + bytes_read, &event, sizeof(event)))
> +#ifdef CONFIG_GPIO_CDEV_V1
> +               if (event_size == sizeof(struct gpio_v2_line_info_changed)) {
> +                       if (copy_to_user(buf + bytes_read, &event, event_size))
> +                               return -EFAULT;
> +               } else {
> +                       struct gpioline_info_changed event_v1;
> +
> +                       gpio_v2_line_info_changed_to_v1(&event, &event_v1);
> +                       if (copy_to_user(buf + bytes_read, &event_v1,
> +                                        event_size))
> +                               return -EFAULT;
> +               }
> +#else
> +               if (copy_to_user(buf + bytes_read, &event, event_size))
>                         return -EFAULT;
> -               bytes_read += sizeof(event);
> +#endif
> +               bytes_read += event_size;
>         } while (count >= bytes_read + sizeof(event));
>
>         return bytes_read;
> --
> 2.28.0
>

Bart

Re: [PATCH v4 07/20] gpiolib: cdev: support GPIO_V2_GET_LINE_IOCTL and GPIO_V2_LINE_GET_VALUES_IOCTL

[Bartosz Golaszewski]

On Sat, Aug 15, 2020 at 3:21 PM Kent Gibson <warthog618@gmail.com> wrote:
>
> On Sat, Aug 15, 2020 at 09:21:22AM +0200, Bartosz Golaszewski wrote:
> > On Sat, Aug 15, 2020 at 8:53 AM Kent Gibson <warthog618@gmail.com> wrote:
> > >
> > > On Fri, Aug 14, 2020 at 09:31:29PM +0200, Bartosz Golaszewski wrote:
> > > > On Fri, Aug 14, 2020 at 5:04 AM Kent Gibson <warthog618@gmail.com> wrote:
> > > > >
> > > > > Add support for requesting lines using the GPIO_V2_GET_LINE_IOCTL, and
> > > > > returning their current values using GPIO_V2_LINE_GET_VALUES_IOCTL.
> > > > >
> > > > > Signed-off-by: Kent Gibson <warthog618@gmail.com>
> > > > > ---
> > > >
> > > > Hi Kent,
> > > >
> > > > not many comments here, just a couple minor details below.
> > > >
> > >
> > > [snip]
> > >
> > > > > +
> > > > > +/**
> > > > > + * struct line - contains the state of a userspace line request
> > > > > + * @gdev: the GPIO device the line request pertains to
> > > > > + * @label: consumer label used to tag descriptors
> > > > > + * @num_descs: the number of descriptors held in the descs array
> > > > > + * @descs: the GPIO descriptors held by this line request, with @num_descs
> > > > > + * elements.
> > > > > + */
> > > > > +struct line {
> > > >
> > > > How about line_request, line_request_data or line_req_ctx? Something
> > > > more intuitive than struct line that doesn't even refer to a single
> > > > line. Same for relevant functions below.
> > > >
> > >
> > > As I've mentioned previously, I'm not a fan of names that include _data,
> > > _ctx, _state, or similar that don't really add anything.
> > >
> >
> > I certainly disagree with you on this. I think it's useful to discern
> > the object itself from data associated with it. Let's consider struct
> > irq_data and let's imagine it would be called struct irq instead. The
> > latter would be misleading - as this struct contains a lot additional
> > fields that form the context for the irq but aren't logically part of
> > the "irq object". And then you have irq_common_data which is even more
> > disconnected from the irq. This also would make using the name "irq"
> > for the variables containing the global irq number confusing.
> >
> > I think the same happens here: we may want to use the name "line" for
> > local variables and then having "struct line_data" (or similar) would
> > make it easier to read.
> >
>
> My counter example to both points is "struct file *file".
>

But struct file is always associated with a single file descriptor,
it's not the case for struct line. I would be fine with this name if
it was an object representing a single line like in libgpiod's
gpiod_line.

> > I'll listen to other's suggestions/voices but personally I think that
> > _ctx, _data etc. suffixes actually make sense.
> >
> > > I did consider line_request, but that was too close to the
> > > gpio_v2_line_request in gpio.d, not just the struct but also the
> > > resulting local variables, particularly in line_create() where they
> > > co-exist.
> > >
> > > Given the ioctl names, GPIO_V2_GET_LINE_IOCTL and
> > > GPIO_V2_LINE_GET/SET_xxx, that all create or operate on this struct, and
> > > that this is within the scope of gpiolib-cdev, the name 'line' seemed the
> > > best fit.
> > >
> >
> > And that's why line_data or line_request_data do make sense IMO.
> >
> > > And how does it not refer to a single line - what are the descs??
> > >
> >
> > I meant the fact that it can refer to multiple lines while being
> > called "struct line". I do find this misleading.
> >
>
> And struct line_data isn't?

struct line sounds as if it represented a single line, struct
line_data is more ambiguous and can be understood both ways IMO.

Bart

Re: [PATCH v4 09/20] gpiolib: cdev: support edge detection for uAPI v2

[Bartosz Golaszewski]

On Fri, Aug 14, 2020 at 5:04 AM Kent Gibson <warthog618@gmail.com> wrote:
>
> Add support for edge detection to lines requested using
> GPIO_V2_GET_LINE_IOCTL.
>
> Signed-off-by: Kent Gibson <warthog618@gmail.com>
> ---
>
> The edge_detector implementation is based on the v1 lineevent implementation.
>
>  drivers/gpio/gpiolib-cdev.c | 316 +++++++++++++++++++++++++++++++++++-
>  drivers/gpio/gpiolib.c      |   2 +
>  drivers/gpio/gpiolib.h      |   2 +
>  3 files changed, 319 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/gpio/gpiolib-cdev.c b/drivers/gpio/gpiolib-cdev.c
> index 28273f3105d3..1d42a01f5414 100644
> --- a/drivers/gpio/gpiolib-cdev.c
> +++ b/drivers/gpio/gpiolib-cdev.c
> @@ -382,11 +382,43 @@ static int linehandle_create(struct gpio_device *gdev, void __user *ip)
>  }
>  #endif /* CONFIG_GPIO_CDEV_V1 */
>
> +/**
> + * struct edge_detector - contains the state of a line edge detector
> + * @line: the corresponding line request
> + * @irq: the interrupt triggered in response to events on this GPIO
> + * @flags: the flags, GPIO_V2_LINE_FLAG_EDGE_RISING and/or
> + * GPIO_V2_LINE_FLAG_EDGE_FALLING, indicating the edge detection applied
> + * @timestamp: cache for the timestamp storing it between hardirq and IRQ
> + * thread, used to bring the timestamp close to the actual event
> + * @seqno: the seqno for the current edge event in the sequence of events
> + * for the corresponding line request. Ths is drawn from the @line.
> + * @line_seqno: the seqno for the current edge event in the sequence of
> + * events for this line.
> + */
> +struct edge_detector {
> +       struct line *line;
> +       unsigned int irq;
> +       u64 flags;
> +       /*
> +        * timestamp and seqno are shared by edge_irq_handler() and
> +        * edge_irq_thread() which are themselves mutually exclusive.
> +        */
> +       u64 timestamp;
> +       u32 seqno;
> +       u32 line_seqno;
> +};
> +
>  /**
>   * struct line - contains the state of a userspace line request
>   * @gdev: the GPIO device the line request pertains to
>   * @label: consumer label used to tag descriptors
>   * @num_descs: the number of descriptors held in the descs array
> + * @wait: wait queue that handles blocking reads of events
> + * @events: KFIFO for the GPIO events
> + * @seqno: the sequence number for edge events generated on all lines in
> + * this line request.  Note that this is not used when @num_descs is 1, as
> + * the line_seqno is then the same and is cheaper to calculate.
> + * @edets: an array of edge detectors, of size @num_descs
>   * @descs: the GPIO descriptors held by this line request, with @num_descs
>   * elements.
>   */
> @@ -394,9 +426,146 @@ struct line {
>         struct gpio_device *gdev;
>         const char *label;
>         u32 num_descs;
> +       wait_queue_head_t wait;
> +       DECLARE_KFIFO_PTR(events, struct gpio_v2_line_event);
> +       atomic_t seqno;
> +       struct edge_detector *edets;
>         struct gpio_desc *descs[];
>  };
>
> +static inline struct gpio_desc *edge_detector_desc(
> +               const struct edge_detector *edet)
> +{
> +       return edet->line->descs[edet - &edet->line->edets[0]];
> +}
> +
> +static irqreturn_t edge_irq_thread(int irq, void *p)
> +{
> +       struct edge_detector *edet = p;
> +       struct line *line = edet->line;
> +       struct gpio_desc *desc = edge_detector_desc(edet);
> +       struct gpio_v2_line_event le;
> +       int ret;
> +
> +       /* Do not leak kernel stack to userspace */
> +       memset(&le, 0, sizeof(le));
> +
> +       /*
> +        * We may be running from a nested threaded interrupt in which case
> +        * we didn't get the timestamp from edge_irq_handler().
> +        */
> +       if (!edet->timestamp) {
> +               le.timestamp = ktime_get_ns();
> +               if (line->num_descs != 1)
> +                       edet->seqno = atomic_inc_return(&line->seqno);
> +       } else {
> +               le.timestamp = edet->timestamp;
> +       }
> +       edet->timestamp = 0;
> +
> +       if (edet->flags == (GPIO_V2_LINE_FLAG_EDGE_RISING |
> +                           GPIO_V2_LINE_FLAG_EDGE_FALLING)) {
> +               int level = gpiod_get_value_cansleep(desc);
> +
> +               if (level)
> +                       /* Emit low-to-high event */
> +                       le.id = GPIO_V2_LINE_EVENT_RISING_EDGE;
> +               else
> +                       /* Emit high-to-low event */
> +                       le.id = GPIO_V2_LINE_EVENT_FALLING_EDGE;
> +       } else if (edet->flags == GPIO_V2_LINE_FLAG_EDGE_RISING) {
> +               /* Emit low-to-high event */
> +               le.id = GPIO_V2_LINE_EVENT_RISING_EDGE;
> +       } else if (edet->flags == GPIO_V2_LINE_FLAG_EDGE_FALLING) {
> +               /* Emit high-to-low event */
> +               le.id = GPIO_V2_LINE_EVENT_FALLING_EDGE;
> +       } else {
> +               return IRQ_NONE;
> +       }
> +       edet->line_seqno++;
> +       le.line_seqno = edet->line_seqno;
> +       le.seqno = (line->num_descs == 1) ? le.line_seqno : edet->seqno;
> +       le.offset = gpio_chip_hwgpio(desc);
> +
> +       ret = kfifo_in_spinlocked_noirqsave(&line->events, &le,
> +                                           1, &line->wait.lock);
> +       if (ret)
> +               wake_up_poll(&line->wait, EPOLLIN);
> +       else
> +               pr_debug_ratelimited("event FIFO is full - event dropped\n");
> +
> +       return IRQ_HANDLED;
> +}
> +
> +static irqreturn_t edge_irq_handler(int irq, void *p)
> +{
> +       struct edge_detector *edet = p;
> +       struct line *line = edet->line;
> +
> +       /*
> +        * Just store the timestamp in hardirq context so we get it as
> +        * close in time as possible to the actual event.
> +        */
> +       edet->timestamp = ktime_get_ns();
> +
> +       if (line->num_descs != 1)
> +               edet->seqno = atomic_inc_return(&line->seqno);
> +
> +       return IRQ_WAKE_THREAD;
> +}
> +
> +static int edge_detector_start(struct edge_detector *edet)
> +{
> +       int ret, irq, irqflags = 0;
> +       struct gpio_desc *desc;
> +
> +       desc = edge_detector_desc(edet);
> +       irq = gpiod_to_irq(desc);
> +
> +       if (irq <= 0)
> +               return -ENODEV;
> +
> +       edet->seqno = 0;
> +       edet->line_seqno = 0;
> +
> +       if (edet->flags & GPIO_V2_LINE_FLAG_EDGE_RISING)
> +               irqflags |= test_bit(FLAG_ACTIVE_LOW, &desc->flags) ?
> +                       IRQF_TRIGGER_FALLING : IRQF_TRIGGER_RISING;
> +       if (edet->flags & GPIO_V2_LINE_FLAG_EDGE_FALLING)
> +               irqflags |= test_bit(FLAG_ACTIVE_LOW, &desc->flags) ?
> +                       IRQF_TRIGGER_RISING : IRQF_TRIGGER_FALLING;
> +       irqflags |= IRQF_ONESHOT;
> +
> +       /* Request a thread to read the events */
> +       ret = request_threaded_irq(irq,
> +                                  edge_irq_handler,
> +                                  edge_irq_thread,
> +                                  irqflags,
> +                                  edet->line->label,
> +                                  edet);
> +       if (ret)
> +               return ret;
> +
> +       edet->irq = irq;
> +       return 0;
> +}
> +
> +static void edge_detector_stop(struct edge_detector *edet)
> +{
> +       if (edet->irq) {
> +               free_irq(edet->irq, edet);
> +               edet->irq = 0;
> +       }
> +}
> +
> +static int edge_detector_setup(struct edge_detector *edet,
> +                              struct gpio_v2_line_config *lc)
> +{
> +       if (edet->flags)
> +               return edge_detector_start(edet);
> +       return 0;
> +}
> +
>  #define GPIO_V2_LINE_BIAS_FLAGS \
>         (GPIO_V2_LINE_FLAG_BIAS_PULL_UP | \
>          GPIO_V2_LINE_FLAG_BIAS_PULL_DOWN | \
> @@ -410,10 +579,15 @@ struct line {
>         (GPIO_V2_LINE_FLAG_OPEN_DRAIN | \
>          GPIO_V2_LINE_FLAG_OPEN_SOURCE)
>
> +#define GPIO_V2_LINE_EDGE_FLAGS \
> +       (GPIO_V2_LINE_FLAG_EDGE_RISING | \
> +        GPIO_V2_LINE_FLAG_EDGE_FALLING)
> +
>  #define GPIO_V2_LINE_VALID_FLAGS \
>         (GPIO_V2_LINE_FLAG_ACTIVE_LOW | \
>          GPIO_V2_LINE_DIRECTION_FLAGS | \
>          GPIO_V2_LINE_DRIVE_FLAGS | \
> +        GPIO_V2_LINE_EDGE_FLAGS | \
>          GPIO_V2_LINE_BIAS_FLAGS)
>
>  static u64 gpio_v2_line_config_flags(struct gpio_v2_line_config *lc,
> @@ -430,6 +604,21 @@ static u64 gpio_v2_line_config_flags(struct gpio_v2_line_config *lc,
>         return lc->flags;
>  }
>
> +static int gpio_v2_line_config_has_edge_detection(struct gpio_v2_line_config *lc)
> +{
> +       int i;
> +
> +       if (lc->flags & GPIO_V2_LINE_EDGE_FLAGS)
> +               return 1;
> +
> +       for (i = 0; i < lc->num_attrs; i--) {
> +               if ((lc->attrs[i].attr.id == GPIO_V2_LINE_ATTR_ID_FLAGS) &&
> +                   (lc->attrs[i].attr.flags & GPIO_V2_LINE_EDGE_FLAGS))
> +                       return 1;
> +       }
> +       return 0;
> +}
> +
>  static int gpio_v2_line_config_output_value(struct gpio_v2_line_config *lc,
>                                             int line_idx)
>  {
> @@ -458,6 +647,11 @@ static int gpio_v2_line_flags_validate(u64 flags)
>             (flags & GPIO_V2_LINE_FLAG_OUTPUT))
>                 return -EINVAL;
>
> +       /* Edge detection requires explicit input. */
> +       if ((flags & GPIO_V2_LINE_EDGE_FLAGS) &&
> +           !(flags & GPIO_V2_LINE_FLAG_INPUT))
> +               return -EINVAL;
> +
>         /*
>          * Do not allow OPEN_SOURCE & OPEN_DRAIN flags in a single request. If
>          * the hardware actually supports enabling both at the same time the
> @@ -518,6 +712,10 @@ static void gpio_v2_line_config_flags_to_desc_flags(u64 flags,
>                 set_bit(FLAG_IS_OUT, flagsp);
>         else if (flags & GPIO_V2_LINE_FLAG_INPUT)
>                 clear_bit(FLAG_IS_OUT, flagsp);
> +       assign_bit(FLAG_EDGE_RISING, flagsp,
> +                  flags & GPIO_V2_LINE_FLAG_EDGE_RISING);
> +       assign_bit(FLAG_EDGE_FALLING, flagsp,
> +                  flags & GPIO_V2_LINE_FLAG_EDGE_FALLING);
>         assign_bit(FLAG_OPEN_DRAIN, flagsp,
>                    flags & GPIO_V2_LINE_FLAG_OPEN_DRAIN);
>         assign_bit(FLAG_OPEN_SOURCE, flagsp,
> @@ -605,14 +803,87 @@ static long line_ioctl_compat(struct file *file, unsigned int cmd,
>  }
>  #endif
>
> +static __poll_t line_poll(struct file *file,
> +                         struct poll_table_struct *wait)
> +{
> +       struct line *line = file->private_data;
> +       __poll_t events = 0;
> +
> +       poll_wait(file, &line->wait, wait);
> +
> +       if (!kfifo_is_empty_spinlocked_noirqsave(&line->events,
> +                                                &line->wait.lock))
> +               events = EPOLLIN | EPOLLRDNORM;
> +
> +       return events;
> +}
> +
> +static ssize_t line_read(struct file *file,
> +                        char __user *buf,
> +                        size_t count,
> +                        loff_t *f_ps)
> +{
> +       struct line *line = file->private_data;
> +       struct gpio_v2_line_event le;
> +       ssize_t bytes_read = 0;
> +       int ret;
> +
> +       if (count < sizeof(le))
> +               return -EINVAL;
> +
> +       do {
> +               spin_lock(&line->wait.lock);
> +               if (kfifo_is_empty(&line->events)) {
> +                       if (bytes_read) {
> +                               spin_unlock(&line->wait.lock);
> +                               return bytes_read;
> +                       }
> +
> +                       if (file->f_flags & O_NONBLOCK) {
> +                               spin_unlock(&line->wait.lock);
> +                               return -EAGAIN;
> +                       }
> +
> +                       ret = wait_event_interruptible_locked(line->wait,
> +                                       !kfifo_is_empty(&line->events));
> +                       if (ret) {
> +                               spin_unlock(&line->wait.lock);
> +                               return ret;
> +                       }
> +               }
> +
> +               ret = kfifo_out(&line->events, &le, 1);
> +               spin_unlock(&line->wait.lock);
> +               if (ret != 1) {
> +                       /*
> +                        * This should never happen - we were holding the
> +                        * lock from the moment we learned the fifo is no
> +                        * longer empty until now.
> +                        */
> +                       ret = -EIO;
> +                       break;
> +               }
> +
> +               if (copy_to_user(buf + bytes_read, &le, sizeof(le)))
> +                       return -EFAULT;
> +               bytes_read += sizeof(le);
> +       } while (count >= bytes_read + sizeof(le));
> +
> +       return bytes_read;
> +}
> +
>  static void line_free(struct line *line)
>  {
>         int i;
>
>         for (i = 0; i < line->num_descs; i++) {
> +               if (line->edets)
> +                       edge_detector_stop(&line->edets[i]);
>                 if (line->descs[i])
>                         gpiod_free(line->descs[i]);
>         }
> +       kfifo_free(&line->events);
> +       kfree(line->edets);
>         kfree(line->label);
>         put_device(&line->gdev->dev);
>         kfree(line);
> @@ -628,6 +899,8 @@ static int line_release(struct inode *inode, struct file *file)
>
>  static const struct file_operations line_fileops = {
>         .release = line_release,
> +       .read = line_read,
> +       .poll = line_poll,
>         .owner = THIS_MODULE,
>         .llseek = noop_llseek,
>         .unlocked_ioctl = line_ioctl,
> @@ -641,7 +914,7 @@ static int line_create(struct gpio_device *gdev, void __user *ip)
>         struct gpio_v2_line_request lr;
>         struct line *line;
>         struct file *file;
> -       int fd, i, ret;
> +       int fd, i, ret, size, has_edge_detection;
>         struct gpio_v2_line_config *lc;
>         unsigned long flags;
>
> @@ -658,6 +931,11 @@ static int line_create(struct gpio_device *gdev, void __user *ip)
>         if (ret)
>                 return ret;
>
> +       /* event_buffer_size only valid with edge detection */
> +       has_edge_detection = gpio_v2_line_config_has_edge_detection(lc);
> +       if (lr.event_buffer_size && !has_edge_detection)
> +               return -EINVAL;
> +
>         line = kzalloc(struct_size(line, descs, lr.num_lines),
>                        GFP_KERNEL);
>         if (!line)
> @@ -666,6 +944,16 @@ static int line_create(struct gpio_device *gdev, void __user *ip)
>         line->gdev = gdev;
>         get_device(&gdev->dev);
>
> +       line->edets = kcalloc(lr.num_lines, sizeof(*line->edets),
> +                             GFP_KERNEL);

You're allocating num_lines of edge detectors even if only certain
lines have edge detection (via attributes). I don't like it but it
made me think about struct line. How about having struct line which
actually only represents a single line (and it contains the relevant
gpio_desc pointer as well as the associated edge detector and any
other data only relevant for this line) and a set of lines would be
aggregated in struct line_request or line_request_data which would
additionally contain common fields? Does that even make sense?

Bart


> +       if (!line->edets) {
> +               ret = -ENOMEM;
> +               goto out_free_line;
> +       }
> +
> +       for (i = 0; i < lr.num_lines; i++)
> +               line->edets[i].line = line;
> +
>         /* Make sure this is terminated */
>         lr.consumer[sizeof(lr.consumer)-1] = '\0';
>         if (strlen(lr.consumer)) {
> @@ -676,6 +964,21 @@ static int line_create(struct gpio_device *gdev, void __user *ip)
>                 }
>         }
>
> +       init_waitqueue_head(&line->wait);
> +       if (has_edge_detection) {
> +               size = lr.event_buffer_size;
> +
> +               if (size > GPIO_V2_LINES_MAX*16)
> +                       size = GPIO_V2_LINES_MAX*16;
> +               else if (size == 0)
> +                       size = lr.num_lines*16;
> +
> +               ret = kfifo_alloc(&line->events, size, GFP_KERNEL);
> +               if (ret)
> +                       goto out_free_line;
> +       }
> +
> +       atomic_set(&line->seqno, 0);
>         line->num_descs = lr.num_lines;
>
>         /* Request each GPIO */
> @@ -714,6 +1017,10 @@ static int line_create(struct gpio_device *gdev, void __user *ip)
>                         ret = gpiod_direction_input(desc);
>                         if (ret)
>                                 goto out_free_line;
> +                       line->edets[i].flags = flags & GPIO_V2_LINE_EDGE_FLAGS;
> +                       ret = edge_detector_setup(&line->edets[i], lc);
> +                       if (ret)
> +                               goto out_free_line;
>                 }
>
>                 blocking_notifier_call_chain(&desc->gdev->notifier,
> @@ -1237,6 +1544,13 @@ static void gpio_desc_to_lineinfo(struct gpio_desc *desc,
>         if (test_bit(FLAG_PULL_UP, &desc->flags))
>                 info->flags |= GPIO_V2_LINE_FLAG_BIAS_PULL_UP;
>
> +       if (test_bit(FLAG_EDGE_RISING, &desc->flags))
> +               info->flags |= GPIO_V2_LINE_FLAG_EDGE_RISING;
> +       if (test_bit(FLAG_EDGE_FALLING, &desc->flags))
> +               info->flags |= GPIO_V2_LINE_FLAG_EDGE_FALLING;
> +
> +       info->num_attrs = 0;
> +
>         spin_unlock_irqrestore(&gpio_lock, flags);
>  }
>
> diff --git a/drivers/gpio/gpiolib.c b/drivers/gpio/gpiolib.c
> index 80137c1b3cdc..e4c81dca7f8b 100644
> --- a/drivers/gpio/gpiolib.c
> +++ b/drivers/gpio/gpiolib.c
> @@ -2041,6 +2041,8 @@ static bool gpiod_free_commit(struct gpio_desc *desc)
>                 clear_bit(FLAG_PULL_UP, &desc->flags);
>                 clear_bit(FLAG_PULL_DOWN, &desc->flags);
>                 clear_bit(FLAG_BIAS_DISABLE, &desc->flags);
> +               clear_bit(FLAG_EDGE_RISING, &desc->flags);
> +               clear_bit(FLAG_EDGE_FALLING, &desc->flags);
>                 clear_bit(FLAG_IS_HOGGED, &desc->flags);
>  #ifdef CONFIG_OF_DYNAMIC
>                 desc->hog = NULL;
> diff --git a/drivers/gpio/gpiolib.h b/drivers/gpio/gpiolib.h
> index 6709f79c02dd..39b356160937 100644
> --- a/drivers/gpio/gpiolib.h
> +++ b/drivers/gpio/gpiolib.h
> @@ -114,6 +114,8 @@ struct gpio_desc {
>  #define FLAG_PULL_UP    13     /* GPIO has pull up enabled */
>  #define FLAG_PULL_DOWN  14     /* GPIO has pull down enabled */
>  #define FLAG_BIAS_DISABLE    15        /* GPIO has pull disabled */
> +#define FLAG_EDGE_RISING     16        /* GPIO CDEV detects rising edge events */
> +#define FLAG_EDGE_FALLING    17        /* GPIO CDEV detects falling edge events */
>
>         /* Connection label */
>         const char              *label;
> --
> 2.28.0
>

Re: [PATCH v4 10/20] gpiolib: cdev: support GPIO_V2_LINE_SET_CONFIG_IOCTL

[Bartosz Golaszewski]

On Fri, Aug 14, 2020 at 5:04 AM Kent Gibson <warthog618@gmail.com> wrote:
>
> Add support for GPIO_V2_LINE_SET_CONFIG_IOCTL, the uAPI v2
> line set config ioctl.
>
> Signed-off-by: Kent Gibson <warthog618@gmail.com>
> ---
>  drivers/gpio/gpiolib-cdev.c | 92 +++++++++++++++++++++++++++++++++++++
>  1 file changed, 92 insertions(+)
>
> diff --git a/drivers/gpio/gpiolib-cdev.c b/drivers/gpio/gpiolib-cdev.c
> index 1d42a01f5414..04472c2b6678 100644
> --- a/drivers/gpio/gpiolib-cdev.c
> +++ b/drivers/gpio/gpiolib-cdev.c
> @@ -16,6 +16,7 @@
>  #include <linux/kernel.h>
>  #include <linux/kfifo.h>
>  #include <linux/module.h>
> +#include <linux/mutex.h>
>  #include <linux/pinctrl/consumer.h>
>  #include <linux/poll.h>
>  #include <linux/spinlock.h>
> @@ -418,6 +419,8 @@ struct edge_detector {
>   * @seqno: the sequence number for edge events generated on all lines in
>   * this line request.  Note that this is not used when @num_descs is 1, as
>   * the line_seqno is then the same and is cheaper to calculate.
> + * @config_mutex: mutex for serializing ioctl() calls to ensure consistency
> + * of configuration, particularly multi-step accesses to desc flags.
>   * @edets: an array of edge detectors, of size @num_descs
>   * @descs: the GPIO descriptors held by this line request, with @num_descs
>   * elements.
> @@ -429,6 +432,7 @@ struct line {
>         wait_queue_head_t wait;
>         DECLARE_KFIFO_PTR(events, struct gpio_v2_line_event);
>         atomic_t seqno;
> +       struct mutex config_mutex;
>         struct edge_detector *edets;
>         struct gpio_desc *descs[];
>  };
> @@ -703,6 +707,30 @@ static int gpio_v2_line_config_validate(struct gpio_v2_line_config *lc,
>         return 0;
>  }
>
> +static int gpio_v2_line_config_change_validate(struct line *line,
> +                                              struct gpio_v2_line_config *lc)
> +{
> +       int i;
> +       u64 flags;
> +       struct gpio_desc *desc;
> +
> +       for (i = 0; i < line->num_descs; i++) {
> +               desc = line->descs[i];
> +               flags = gpio_v2_line_config_flags(lc, i);
> +               /* disallow edge detection changes */
> +               if (line->edets[i].flags != (flags & GPIO_V2_LINE_EDGE_FLAGS))
> +                       return -EINVAL;
> +
> +               if (line->edets[i].flags) {
> +                       /* disallow polarity changes */
> +                       if (test_bit(FLAG_ACTIVE_LOW, &desc->flags) !=
> +                           ((flags & GPIO_V2_LINE_FLAG_ACTIVE_LOW) != 0))
> +                               return -EINVAL;
> +               }
> +       }
> +       return 0;
> +}
> +
>  static void gpio_v2_line_config_flags_to_desc_flags(u64 flags,
>                                                     unsigned long *flagsp)
>  {
> @@ -783,6 +811,67 @@ static long line_get_values(struct line *line, void __user *ip)
>         return 0;
>  }
>
> +static long line_set_config_locked(struct line *line,
> +                                  struct gpio_v2_line_config *lc)

I think that the general consensus in the kernel is to suffix
functions that need to be called with some lock taken outside them
with _unlocked (as in: the function is unlocked on its own).
Alternatively such routines are prefixed with __ (__line_set_config())
but I know Linus prefers the former.

Bart

> +{
> +       struct gpio_desc *desc;
> +       int i, ret;
> +       u64 flags;
> +
> +       ret = gpio_v2_line_config_change_validate(line, lc);
> +       if (ret)
> +               return ret;
> +
> +       for (i = 0; i < line->num_descs; i++) {
> +               desc = line->descs[i];
> +               flags = gpio_v2_line_config_flags(lc, i);
> +
> +               gpio_v2_line_config_flags_to_desc_flags(flags, &desc->flags);
> +               /*
> +                * Lines have to be requested explicitly for input
> +                * or output, else the line will be treated "as is".
> +                */
> +               if (flags & GPIO_V2_LINE_FLAG_OUTPUT) {
> +                       int val = gpio_v2_line_config_output_value(lc, i);
> +
> +                       edge_detector_stop(&line->edets[i]);
> +                       ret = gpiod_direction_output(desc, val);
> +                       if (ret)
> +                               return ret;
> +               } else if (flags & GPIO_V2_LINE_FLAG_INPUT) {
> +                       ret = gpiod_direction_input(desc);
> +                       if (ret)
> +                               return ret;
> +               }
> +
> +               blocking_notifier_call_chain(&desc->gdev->notifier,
> +                                            GPIO_V2_LINE_CHANGED_CONFIG,
> +                                            desc);
> +       }
> +       return 0;
> +}
> +
> +static long line_set_config(struct line *line, void __user *ip)
> +{
> +       struct gpio_v2_line_config lc;
> +       int ret;
> +
> +       if (copy_from_user(&lc, ip, sizeof(lc)))
> +               return -EFAULT;
> +
> +       ret = gpio_v2_line_config_validate(&lc, line->num_descs);
> +       if (ret)
> +               return ret;
> +
> +       mutex_lock(&line->config_mutex);
> +
> +       ret = line_set_config_locked(line, &lc);
> +
> +       mutex_unlock(&line->config_mutex);
> +
> +       return ret;
> +}
> +
>  static long line_ioctl(struct file *file, unsigned int cmd,
>                        unsigned long arg)
>  {
> @@ -791,6 +880,8 @@ static long line_ioctl(struct file *file, unsigned int cmd,
>
>         if (cmd == GPIO_V2_LINE_GET_VALUES_IOCTL)
>                 return line_get_values(line, ip);
> +       else if (cmd == GPIO_V2_LINE_SET_CONFIG_IOCTL)
> +               return line_set_config(line, ip);
>
>         return -EINVAL;
>  }
> @@ -964,6 +1055,7 @@ static int line_create(struct gpio_device *gdev, void __user *ip)
>                 }
>         }
>
> +       mutex_init(&line->config_mutex);
>         init_waitqueue_head(&line->wait);
>         if (has_edge_detection) {
>                 size = lr.event_buffer_size;
> --
> 2.28.0
>

Re: [PATCH v4 11/20] gpiolib: cdev: support GPIO_V2_LINE_SET_VALUES_IOCTL

[Bartosz Golaszewski]

On Fri, Aug 14, 2020 at 5:04 AM Kent Gibson <warthog618@gmail.com> wrote:
>
> Add support for the GPIO_V2_LINE_SET_VALUES_IOCTL.
>
> Signed-off-by: Kent Gibson <warthog618@gmail.com>
> ---

Just the same thing as with patch 10/20 regarding the
_locked/_unlocked suffix. I don't have other comments, looks good to
me.

Bart

[snip]

Re: [PATCH v4 12/20] gpiolib: cdev: support setting debounce

[Bartosz Golaszewski]

On Fri, Aug 14, 2020 at 5:05 AM Kent Gibson <warthog618@gmail.com> wrote:
>
> Add support for setting debounce on a line via the GPIO uAPI.
> Where debounce is not supported by hardware, a software debounce is
> provided.
>
> Signed-off-by: Kent Gibson <warthog618@gmail.com>
> ---
>
> The implementation of the software debouncer waits for the line to be
> stable for the debounce period before determining if a level change,
> and a corresponding edge event, has occurred.  This provides maximum
> protection against glitches, but also introduces a debounce_period
> latency to edge events.
>
> The software debouncer is integrated with the edge detection as it
> utilises the line interrupt, and integration is simpler than getting
> the two to interwork.  Where software debounce AND edge detection is
> required, the debouncer provides both.
>
> Due to the tight integration between the debouncer and edge detection,
> and to avoid particular corner cases, it is not allowed to alter the
> debounce value if edge detection is enabled.  Changing the debounce with
> edge detection enabled is a very unlikely use case, so it is preferable
> to disallow it rather than complicate the code to allow it.
> Should the user wish to alter the debounce value in such cases they will
> need to release and re-request the line.
>
> Changes for v4:
>  - fix handling of mask in line_get_values
>
> Changes for v3:
>  - only GPIO_V2 field renaming
>
> Changes for v2:
>  - improve documentation on fields shared by threads.
>  - use READ_ONCE/WRITE_ONCE for shared fields rather than atomic_t
>    which was overkill.
>
>  drivers/gpio/gpiolib-cdev.c | 265 +++++++++++++++++++++++++++++++++++-
>  drivers/gpio/gpiolib.h      |   4 +
>  2 files changed, 263 insertions(+), 6 deletions(-)
>
> diff --git a/drivers/gpio/gpiolib-cdev.c b/drivers/gpio/gpiolib-cdev.c
> index de88b7a5ba0f..77fabf815de8 100644
> --- a/drivers/gpio/gpiolib-cdev.c
> +++ b/drivers/gpio/gpiolib-cdev.c
> @@ -6,6 +6,7 @@
>  #include <linux/build_bug.h>
>  #include <linux/cdev.h>
>  #include <linux/compat.h>
> +#include <linux/compiler.h>
>  #include <linux/device.h>
>  #include <linux/err.h>
>  #include <linux/file.h>
> @@ -22,6 +23,7 @@
>  #include <linux/spinlock.h>
>  #include <linux/timekeeping.h>
>  #include <linux/uaccess.h>
> +#include <linux/workqueue.h>
>  #include <uapi/linux/gpio.h>
>
>  #include "gpiolib.h"
> @@ -395,6 +397,9 @@ static int linehandle_create(struct gpio_device *gdev, void __user *ip)
>   * for the corresponding line request. Ths is drawn from the @line.
>   * @line_seqno: the seqno for the current edge event in the sequence of
>   * events for this line.
> + * @work: the worker that implements software debouncing
> + * @sw_debounced: flag indicating if the software debouncer is active
> + * @level: the current debounced physical level of the line
>   */
>  struct edge_detector {
>         struct line *line;
> @@ -406,7 +411,27 @@ struct edge_detector {
>          */
>         u64 timestamp;
>         u32 seqno;
> +       /*
> +        * line_seqno is used by either edge_irq_thread() or
> +        * debounce_work_func() which are themselves mutually exclusive.
> +        */
>         u32 line_seqno;
> +       /*
> +        * -- debouncer specific fields --
> +        */
> +       struct delayed_work work;
> +       /*
> +        * sw_debounce is shared by line_set_config(), which is the only
> +        * setter, and line_ioctl(), which can live with a slightly stale
> +        * value.
> +        */
> +       unsigned int sw_debounced;
> +       /*
> +        * level is shared by debounce_work_func(), which is the only
> +        * setter, and line_ioctl() which can live with a slightly stale
> +        * value.
> +        */
> +       unsigned int level;
>  };
>
>  /**
> @@ -523,6 +548,10 @@ static int edge_detector_start(struct edge_detector *edet)
>         int ret, irq, irqflags = 0;
>         struct gpio_desc *desc;
>
> +       if (READ_ONCE(edet->sw_debounced))
> +               /* debouncer is setup and will provide edge detection */
> +               return 0;
> +
>         desc = edge_detector_desc(edet);
>         irq = gpiod_to_irq(desc);
>
> @@ -554,17 +583,215 @@ static int edge_detector_start(struct edge_detector *edet)
>         return 0;
>  }
>
> +/*
> + * returns the current debounced logical value.
> + */
> +static int debounced_value(struct edge_detector *edet)
> +{
> +       int value;
> +
> +       /*
> +        * minor race - debouncer may be stopped here, so edge_detector_stop
> +        * must leave the value unchanged so the following will read the level
> +        * from when the debouncer was last running.
> +        */
> +       value = READ_ONCE(edet->level);
> +
> +       if (test_bit(FLAG_ACTIVE_LOW, &edge_detector_desc(edet)->flags))
> +               value = !value;
> +
> +       return value;
> +}
> +
> +static irqreturn_t debounce_irq_handler(int irq, void *p)
> +{
> +       struct edge_detector *edet = p;
> +       struct gpio_desc *desc = edge_detector_desc(edet);
> +
> +       mod_delayed_work(system_wq,
> +                        &edet->work,
> +                        usecs_to_jiffies(READ_ONCE(desc->debounce_period)));
> +
> +       return IRQ_HANDLED;
> +}
> +
> +static void debounce_work_func(struct work_struct *work)
> +{
> +       struct gpio_v2_line_event le;
> +       int ret, level;
> +       struct edge_detector *edet =
> +               container_of(work, struct edge_detector, work.work);
> +       struct gpio_desc *desc = edge_detector_desc(edet);
> +       struct line *line;
> +
> +       level = gpiod_get_raw_value_cansleep(desc);
> +       if (level < 0) {
> +               pr_debug_ratelimited("debouncer failed to read line value\n");
> +               return;
> +       }
> +
> +       if (READ_ONCE(edet->level) == level)
> +               return;
> +
> +       WRITE_ONCE(edet->level, level);
> +
> +       /* -- edge detection -- */
> +       if (!edet->flags)
> +               return;
> +
> +       /* switch from physical level to logical - if they differ */
> +       if (test_bit(FLAG_ACTIVE_LOW, &desc->flags))
> +               level = !level;
> +
> +       /* ignore edges that are not being monitored */
> +       if (((edet->flags == GPIO_V2_LINE_FLAG_EDGE_RISING) && !level) ||
> +           ((edet->flags == GPIO_V2_LINE_FLAG_EDGE_FALLING) && level))
> +               return;
> +
> +       /* Do not leak kernel stack to userspace */
> +       memset(&le, 0, sizeof(le));
> +
> +       line = edet->line;
> +       le.timestamp = ktime_get_ns();
> +       le.offset = gpio_chip_hwgpio(desc);
> +       edet->line_seqno++;
> +       le.line_seqno = edet->line_seqno;
> +       le.seqno = (line->num_descs == 1) ?
> +               le.line_seqno : atomic_inc_return(&line->seqno);
> +
> +       if (level)
> +               /* Emit low-to-high event */
> +               le.id = GPIO_V2_LINE_EVENT_RISING_EDGE;
> +       else
> +               /* Emit high-to-low event */
> +               le.id = GPIO_V2_LINE_EVENT_FALLING_EDGE;
> +
> +       ret = kfifo_in_spinlocked_noirqsave(&line->events, &le,
> +                                           1, &line->wait.lock);
> +       if (ret)
> +               wake_up_poll(&line->wait, EPOLLIN);
> +       else
> +               pr_debug_ratelimited("event FIFO is full - event dropped\n");
> +}
> +
> +static int debounce_setup(struct edge_detector *edet,
> +                         unsigned int debounce_period)
> +{
> +       int ret, level, irq, irqflags;
> +       struct gpio_desc *desc = edge_detector_desc(edet);
> +
> +       /* try hardware */
> +       ret = gpiod_set_debounce(desc, debounce_period);
> +       if (!ret) {
> +               WRITE_ONCE(desc->debounce_period, debounce_period);
> +               return ret;
> +       }
> +       if (ret != -ENOTSUPP)
> +               return ret;
> +
> +       if (debounce_period) {
> +               /* setup software debounce */
> +               level = gpiod_get_raw_value_cansleep(desc);
> +               if (level < 0)
> +                       return level;
> +
> +               irq = gpiod_to_irq(desc);
> +               if (irq <= 0)
> +                       return -ENODEV;
> +
> +               WRITE_ONCE(edet->level, level);
> +               edet->line_seqno = 0;
> +               irqflags = IRQF_TRIGGER_FALLING | IRQF_TRIGGER_RISING;
> +               ret = request_irq(irq,
> +                                 debounce_irq_handler,
> +                                 irqflags,
> +                                 edet->line->label,
> +                                 edet);

Nit: Don't break lines too eagerly: this call could fit in two lines.
I think I saw some other instances in other patches.

> +               if (ret)
> +                       return ret;
> +
> +               WRITE_ONCE(edet->sw_debounced, 1);
> +               edet->irq = irq;
> +       }
> +       WRITE_ONCE(desc->debounce_period, debounce_period);
> +       return 0;
> +}
> +
>  static void edge_detector_stop(struct edge_detector *edet)
>  {
> +       struct gpio_desc *desc = edge_detector_desc(edet);
> +
>         if (edet->irq) {
>                 free_irq(edet->irq, edet);
>                 edet->irq = 0;
>         }
> +
> +       cancel_delayed_work_sync(&edet->work);
> +       WRITE_ONCE(edet->sw_debounced, 0);
> +       /* do not change edet->level - see comment in debounced_value */
> +
> +       if (desc)
> +               WRITE_ONCE(desc->debounce_period, 0);
> +}
> +
> +static int debounce_update(struct edge_detector *edet,
> +                          unsigned int debounce_period)
> +{
> +       struct gpio_desc *desc = edge_detector_desc(edet);
> +
> +       if (READ_ONCE(desc->debounce_period) == debounce_period)
> +               return 0;
> +
> +       if (!READ_ONCE(edet->sw_debounced))
> +               return debounce_setup(edet, debounce_period);
> +
> +       if (!debounce_period)
> +               edge_detector_stop(edet);
> +       else
> +               WRITE_ONCE(desc->debounce_period, debounce_period);
> +       return 0;
> +}
> +
> +static int gpio_v2_line_config_debounced(struct gpio_v2_line_config *lc,
> +                                        int line_idx)
> +{
> +       int i;
> +       unsigned long long mask = BIT_ULL(line_idx);
> +
> +       for (i = 0; i < lc->num_attrs; i++) {
> +               if ((lc->attrs[i].attr.id == GPIO_V2_LINE_ATTR_ID_DEBOUNCE) &&
> +                   (lc->attrs[i].mask & mask))
> +                       return 1;
> +       }
> +       return 0;
> +}
> +
> +static u32 gpio_v2_line_config_debounce_period(struct gpio_v2_line_config *lc,
> +                                              int line_idx)
> +{
> +       int i;
> +       unsigned long long mask = BIT_ULL(line_idx);
> +
> +       for (i = 0; i < lc->num_attrs; i++) {
> +               if ((lc->attrs[i].attr.id == GPIO_V2_LINE_ATTR_ID_DEBOUNCE) &&
> +                   (lc->attrs[i].mask & mask))
> +                       return lc->attrs[i].attr.debounce_period;
> +       }
> +       return 0;
>  }
>
>  static int edge_detector_setup(struct edge_detector *edet,
> -                              struct gpio_v2_line_config *lc)
> +                              struct gpio_v2_line_config *lc,
> +                              int line_idx)
>  {
> +       int ret;
> +
> +       if (gpio_v2_line_config_debounced(lc, line_idx)) {
> +               ret = debounce_setup(edet,
> +                       gpio_v2_line_config_debounce_period(lc, line_idx));
> +               if (ret)
> +                       return ret;
> +       }
>         if (edet->flags)
>                 return edge_detector_start(edet);
>         return 0;
> @@ -703,6 +930,11 @@ static int gpio_v2_line_config_validate(struct gpio_v2_line_config *lc,
>                 ret = gpio_v2_line_flags_validate(flags);
>                 if (ret)
>                         return ret;
> +
> +               /* debounce requires explicit input */
> +               if (gpio_v2_line_config_debounced(lc, i) &&
> +                   !(flags & GPIO_V2_LINE_FLAG_INPUT))
> +                       return -EINVAL;
>         }
>         return 0;
>  }
> @@ -761,7 +993,7 @@ static long line_get_values(struct line *line, void __user *ip)
>         struct gpio_v2_line_values lv;
>         DECLARE_BITMAP(vals, GPIO_V2_LINES_MAX);
>         struct gpio_desc **descs;
> -       int ret, i, didx, num_get = 0;
> +       int ret, i, val, didx, num_get = 0;
>
>         /* NOTE: It's ok to read values of output lines. */
>         if (copy_from_user(&lv, ip, sizeof(lv)))
> @@ -799,7 +1031,11 @@ static long line_get_values(struct line *line, void __user *ip)
>         lv.bits = 0;
>         for (didx = 0, i = 0; i < line->num_descs; i++) {
>                 if (lv.mask & BIT_ULL(i)) {
> -                       if (test_bit(didx, vals))
> +                       if (line->edets[i].sw_debounced)
> +                               val = debounced_value(&line->edets[i]);
> +                       else
> +                               val = test_bit(didx, vals);
> +                       if (val)
>                                 lv.bits |= BIT_ULL(i);
>                         didx++;
>                 }
> @@ -907,6 +1143,12 @@ static long line_set_config_locked(struct line *line,
>                         ret = gpiod_direction_input(desc);
>                         if (ret)
>                                 return ret;
> +                       if (gpio_v2_line_config_debounced(lc, i)) {
> +                               ret = debounce_update(&line->edets[i],
> +                                       gpio_v2_line_config_debounce_period(lc, i));
> +                               if (ret)
> +                                       return ret;
> +                       }
>                 }
>
>                 blocking_notifier_call_chain(&desc->gdev->notifier,
> @@ -1109,8 +1351,11 @@ static int line_create(struct gpio_device *gdev, void __user *ip)
>                 goto out_free_line;
>         }
>
> -       for (i = 0; i < lr.num_lines; i++)
> +       for (i = 0; i < lr.num_lines; i++) {
>                 line->edets[i].line = line;
> +               WRITE_ONCE(line->edets[i].sw_debounced, 0);
> +               INIT_DELAYED_WORK(&line->edets[i].work, debounce_work_func);
> +       }
>
>         /* Make sure this is terminated */
>         lr.consumer[sizeof(lr.consumer)-1] = '\0';
> @@ -1177,7 +1422,7 @@ static int line_create(struct gpio_device *gdev, void __user *ip)
>                         if (ret)
>                                 goto out_free_line;
>                         line->edets[i].flags = flags & GPIO_V2_LINE_EDGE_FLAGS;
> -                       ret = edge_detector_setup(&line->edets[i], lc);
> +                       ret = edge_detector_setup(&line->edets[i], lc, i);
>                         if (ret)
>                                 goto out_free_line;
>                 }
> @@ -1649,6 +1894,8 @@ static void gpio_desc_to_lineinfo(struct gpio_desc *desc,
>         struct gpio_chip *gc = desc->gdev->chip;
>         bool ok_for_pinctrl;
>         unsigned long flags;
> +       u32 debounce_period;
> +       int num_attrs = 0;
>
>         memset(info, 0, sizeof(*info));
>         info->offset = gpio_chip_hwgpio(desc);
> @@ -1708,7 +1955,13 @@ static void gpio_desc_to_lineinfo(struct gpio_desc *desc,
>         if (test_bit(FLAG_EDGE_FALLING, &desc->flags))
>                 info->flags |= GPIO_V2_LINE_FLAG_EDGE_FALLING;
>
> -       info->num_attrs = 0;
> +       debounce_period = READ_ONCE(desc->debounce_period);
> +       if (debounce_period) {
> +               info->attrs[num_attrs].id = GPIO_V2_LINE_ATTR_ID_DEBOUNCE;
> +               info->attrs[num_attrs].debounce_period = debounce_period;
> +               num_attrs++;
> +       }
> +       info->num_attrs = num_attrs;

AFAICT this (reading it in gpio_desc_to_lineinfo) is the only reason
to store the debounce period in struct gpio_desc. I'm wondering if we
can avoid extending this struct only for such uncommon case and store
it elsewhere. In all other cases where you read or write to it - you
have access to the underlying edge detector. Would the single-line
struct line I suggested elsewhere be a good place? On the other hand
I'm not sure how to get it having only the desc. I need to think about
it more.

Bart

>
>         spin_unlock_irqrestore(&gpio_lock, flags);
>  }
> diff --git a/drivers/gpio/gpiolib.h b/drivers/gpio/gpiolib.h
> index 39b356160937..671805a79a15 100644
> --- a/drivers/gpio/gpiolib.h
> +++ b/drivers/gpio/gpiolib.h
> @@ -124,6 +124,10 @@ struct gpio_desc {
>  #ifdef CONFIG_OF_DYNAMIC
>         struct device_node      *hog;
>  #endif
> +#ifdef CONFIG_GPIO_CDEV
> +       /* debounce period in microseconds */
> +       unsigned int            debounce_period;
> +#endif
>  };
>
>  int gpiod_request(struct gpio_desc *desc, const char *label);
> --
> 2.28.0
>

Re: [PATCH v4 00/20] gpio: cdev: add uAPI v2

[Bartosz Golaszewski]

On Fri, Aug 14, 2020 at 5:03 AM Kent Gibson <warthog618@gmail.com> wrote:
>
> This patchset defines and implements adds a new version of the
> GPIO CDEV uAPI to address existing 32/64-bit alignment issues, add
> support for debounce, event sequence numbers, and allowing for requested
> lines with different configurations.
> It provides some future proofing by adding optional configuration fields
> and padding reserved for future use.
>
> The series can be partitioned into two sets; the first eleven
> contain the v2 uAPI implementation, and the final seven port
> the GPIO tools to the v2 uAPI and extend them to use new uAPI features.
>
> The more complicated patches include their own commentary where
> appropriate.
>
> Cheers,
> Kent.
>
> Changes for v4:
>  - bitmap width clarification in gpiod.h (patch 04)
>  - fix info offset initialisation bug (patch 08 and inserting patch 01)
>  - replace strncpy with strscpy to remove compiler warnings
>    (patch 08 and inserting patch 02)
>  - fix mask handling in line_get_values (patch 07)
>
> Changes for v3:
>  - disabling the character device from the build requires EXPERT
>  - uAPI revisions (see patch 02)
>  - replace padding_not_zeroed with calls to memchr_inv
>  - don't use bitops on 64-bit flags as that doesn't work on BE-32
>  - accept first attribute matching a line in gpio_v2_line_config.attrs
>    rather than the last
>  - rework lsgpio port to uAPI v2 as flags reverted to v1 like layout
>    (since patch v2)
>  - swapped patches 17 and 18 to apply debounce to multiple monitored
>    lines
>
> Changes for v2:
>  - split out cleanup patches into a separate series.
>  - split implementation patch into a patch for each ioctl or major feature.
>  - split tool port patch into a patch per tool.
>  - rework uAPI to allow requested lines with different configurations.
>
>
> Kent Gibson (20):
>   gpiolib: cdev: desc_to_lineinfo should set info offset
>   gpiolib: cdev: replace strncpy with strscpy
>   gpio: uapi: define GPIO_MAX_NAME_SIZE for array sizes
>   gpio: uapi: define uAPI v2
>   gpiolib: make cdev a build option
>   gpiolib: add build option for CDEV v1 ABI
>   gpiolib: cdev: support GPIO_V2_GET_LINE_IOCTL and
>     GPIO_V2_LINE_GET_VALUES_IOCTL
>   gpiolib: cdev: support GPIO_V2_GET_LINEINFO_IOCTL and
>     GPIO_V2_GET_LINEINFO_WATCH_IOCTL
>   gpiolib: cdev: support edge detection for uAPI v2
>   gpiolib: cdev: support GPIO_V2_LINE_SET_CONFIG_IOCTL
>   gpiolib: cdev: support GPIO_V2_LINE_SET_VALUES_IOCTL
>   gpiolib: cdev: support setting debounce
>   gpio: uapi: document uAPI v1 as deprecated
>   tools: gpio: port lsgpio to v2 uAPI
>   tools: gpio: port gpio-watch to v2 uAPI
>   tools: gpio: rename nlines to num_lines
>   tools: gpio: port gpio-hammer to v2 uAPI
>   tools: gpio: port gpio-event-mon to v2 uAPI
>   tools: gpio: add multi-line monitoring to gpio-event-mon
>   tools: gpio: add debounce support to gpio-event-mon
>
>  drivers/gpio/Kconfig        |   29 +-
>  drivers/gpio/Makefile       |    2 +-
>  drivers/gpio/gpiolib-cdev.c | 1354 +++++++++++++++++++++++++++++++++--
>  drivers/gpio/gpiolib-cdev.h |   15 +
>  drivers/gpio/gpiolib.c      |    2 +
>  drivers/gpio/gpiolib.h      |    6 +
>  include/uapi/linux/gpio.h   |  316 +++++++-
>  tools/gpio/gpio-event-mon.c |  146 ++--
>  tools/gpio/gpio-hammer.c    |   56 +-
>  tools/gpio/gpio-utils.c     |  127 ++--
>  tools/gpio/gpio-utils.h     |   50 +-
>  tools/gpio/gpio-watch.c     |   16 +-
>  tools/gpio/lsgpio.c         |   60 +-
>  13 files changed, 1949 insertions(+), 230 deletions(-)
>
>
> base-commit: 22cc422070d9a9a399f8a70b89f1b852945444cb
> --
> 2.28.0
>

Hi Kent!

The series looks quite good to me and I think we're on track to get it
in for v5.10. I'd love to have Andy (Cc'd) take a look as well. There
are some nits here and there but as long as we get the ABI right, any
implementation details can be ironed out later.

I need to think about some details a bit more but I really like the
current state of the patches.

Bart

Re: [PATCH v4 00/20] gpio: cdev: add uAPI v2

[Andy Shevchenko]

On Mon, Aug 17, 2020 at 08:24:24PM +0200, Bartosz Golaszewski wrote:
> On Fri, Aug 14, 2020 at 5:03 AM Kent Gibson <warthog618@gmail.com> wrote:
> >
> > This patchset defines and implements adds a new version of the
> > GPIO CDEV uAPI to address existing 32/64-bit alignment issues, add
> > support for debounce, event sequence numbers, and allowing for requested
> > lines with different configurations.
> > It provides some future proofing by adding optional configuration fields
> > and padding reserved for future use.
> >
> > The series can be partitioned into two sets; the first eleven
> > contain the v2 uAPI implementation, and the final seven port
> > the GPIO tools to the v2 uAPI and extend them to use new uAPI features.
> >
> > The more complicated patches include their own commentary where
> > appropriate.

> The series looks quite good to me and I think we're on track to get it
> in for v5.10. I'd love to have Andy (Cc'd) take a look as well. There
> are some nits here and there but as long as we get the ABI right, any
> implementation details can be ironed out later.
> 
> I need to think about some details a bit more but I really like the
> current state of the patches.

First of all, I apologize for being silent, I'm quite busy with internal
development / work.

Second, I didn't hear further why we can't fix current ABI as proposed by Arnd
and see what we will have afterwards?

Third, I'm not satisfied with the approach of wasting some memory for padding
and I think the proper solution for the ABI is to have versioning inside the
structures.

What do you think?

-- 
With Best Regards,
Andy Shevchenko

Re: [PATCH v4 00/20] gpio: cdev: add uAPI v2

[Bartosz Golaszewski]

On Mon, Aug 17, 2020 at 8:40 PM Andy Shevchenko
<andriy.shevchenko@linux.intel.com> wrote:
>
> On Mon, Aug 17, 2020 at 08:24:24PM +0200, Bartosz Golaszewski wrote:
> > On Fri, Aug 14, 2020 at 5:03 AM Kent Gibson <warthog618@gmail.com> wrote:
> > >
> > > This patchset defines and implements adds a new version of the
> > > GPIO CDEV uAPI to address existing 32/64-bit alignment issues, add
> > > support for debounce, event sequence numbers, and allowing for requested
> > > lines with different configurations.
> > > It provides some future proofing by adding optional configuration fields
> > > and padding reserved for future use.
> > >
> > > The series can be partitioned into two sets; the first eleven
> > > contain the v2 uAPI implementation, and the final seven port
> > > the GPIO tools to the v2 uAPI and extend them to use new uAPI features.
> > >
> > > The more complicated patches include their own commentary where
> > > appropriate.
>
> > The series looks quite good to me and I think we're on track to get it
> > in for v5.10. I'd love to have Andy (Cc'd) take a look as well. There
> > are some nits here and there but as long as we get the ABI right, any
> > implementation details can be ironed out later.
> >
> > I need to think about some details a bit more but I really like the
> > current state of the patches.
>
> First of all, I apologize for being silent, I'm quite busy with internal
> development / work.
>
> Second, I didn't hear further why we can't fix current ABI as proposed by Arnd
> and see what we will have afterwards?
>

Sure we can get back to fixing it but it will only address a single
bug and still not allow us to add new features and simplifications. Do
you mind rebasing your old patch on top of v5.9-rc1?

> Third, I'm not satisfied with the approach of wasting some memory for padding
> and I think the proper solution for the ABI is to have versioning inside the
> structures.
>
> What do you think?
>

Wasting a bit of memory is fine with me. As long as we're not copying
more than a page-worth of memory between the kernel and user-space,
the overhead is insignificant.

I prefer to make structs extensible over adding new versions in the future.

Bart

Re: [PATCH v4 09/20] gpiolib: cdev: support edge detection for uAPI v2

[Kent Gibson]

On Sun, Aug 16, 2020 at 04:32:34PM +0200, Bartosz Golaszewski wrote:
> On Fri, Aug 14, 2020 at 5:04 AM Kent Gibson <warthog618@gmail.com> wrote:
> >
> > Add support for edge detection to lines requested using
> > GPIO_V2_GET_LINE_IOCTL.
> >
[snip]

> >
> > +       /* event_buffer_size only valid with edge detection */
> > +       has_edge_detection = gpio_v2_line_config_has_edge_detection(lc);
> > +       if (lr.event_buffer_size && !has_edge_detection)
> > +               return -EINVAL;
> > +
> >         line = kzalloc(struct_size(line, descs, lr.num_lines),
> >                        GFP_KERNEL);
> >         if (!line)
> > @@ -666,6 +944,16 @@ static int line_create(struct gpio_device *gdev, void __user *ip)
> >         line->gdev = gdev;
> >         get_device(&gdev->dev);
> >
> > +       line->edets = kcalloc(lr.num_lines, sizeof(*line->edets),
> > +                             GFP_KERNEL);
> 
> You're allocating num_lines of edge detectors even if only certain
> lines have edge detection (via attributes). I don't like it but it
> made me think about struct line. How about having struct line which
> actually only represents a single line (and it contains the relevant
> gpio_desc pointer as well as the associated edge detector and any
> other data only relevant for this line) and a set of lines would be
> aggregated in struct line_request or line_request_data which would
> additionally contain common fields? Does that even make sense?
> 

You are right, and it makes total sense.

I'm not totally thrilled with the block allocation either, but an
earlier draft with edge detectors/debouncers created and destroyed as
required resulted in complicated lifecycle management that this approach
avoids.

I'll have a look at restructuring it as you suggest.
The only downside that springs to mind is that the gpiolib API expects
a desc array, which we'll no longer have handy, so it would have to be
built on the fly as per the sparse gets/sets.

Cheers,
Kent.

Re: [PATCH v4 12/20] gpiolib: cdev: support setting debounce

[Kent Gibson]

On Mon, Aug 17, 2020 at 08:21:58PM +0200, Bartosz Golaszewski wrote:
> On Fri, Aug 14, 2020 at 5:05 AM Kent Gibson <warthog618@gmail.com> wrote:
> >
> > Add support for setting debounce on a line via the GPIO uAPI.
> > Where debounce is not supported by hardware, a software debounce is
> > provided.
> >
> > Signed-off-by: Kent Gibson <warthog618@gmail.com>
> > ---

[snip]

> > +       debounce_period = READ_ONCE(desc->debounce_period);
> > +       if (debounce_period) {
> > +               info->attrs[num_attrs].id = GPIO_V2_LINE_ATTR_ID_DEBOUNCE;
> > +               info->attrs[num_attrs].debounce_period = debounce_period;
> > +               num_attrs++;
> > +       }
> > +       info->num_attrs = num_attrs;
> 
> AFAICT this (reading it in gpio_desc_to_lineinfo) is the only reason
> to store the debounce period in struct gpio_desc. I'm wondering if we
> can avoid extending this struct only for such uncommon case and store
> it elsewhere. In all other cases where you read or write to it - you
> have access to the underlying edge detector. Would the single-line
> struct line I suggested elsewhere be a good place? On the other hand
> I'm not sure how to get it having only the desc. I need to think about
> it more.
> 

Yeah, it is stored there so it can be returned by lineinfo_get() for the
GPIO_V2_GET_LINEINFO_IOCTL and GPIO_V2_GET_LINEINFO_WATCH_IOCTL.
And the same applies to any future config fields.
I would also like to not pollute the desc, or anything else in gpiolib,
but wasn't sure where else to put it.

I'm open to suggestions.

Cheers,
Kent.