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From: Kent Gibson <warthog618@gmail.com>
To: linux-gpio@vger.kernel.org, bgolaszewski@baylibre.com,
	linus.walleij@linaro.org, bamv2005@gmail.com
Cc: drew@pdp7.com, thomas.petazzoni@bootlin.com,
	Kent Gibson <warthog618@gmail.com>
Subject: [PATCH v6 3/7] gpiolib: add support for disabling line bias
Date: Tue,  5 Nov 2019 10:04:25 +0800	[thread overview]
Message-ID: <20191105020429.18942-4-warthog618@gmail.com> (raw)
In-Reply-To: <20191105020429.18942-1-warthog618@gmail.com>

Allow pull up/down bias to be disabled, allowing the line to float
or to be biased only by external circuitry.
Use case is for where the bias has been applied previously, either
by default or by the user, but that setting may conflict with the
current use of the line.

Signed-off-by: Kent Gibson <warthog618@gmail.com>
---
 drivers/gpio/gpiolib.c    | 61 ++++++++++++++++++++++++++++++++-------
 drivers/gpio/gpiolib.h    |  1 +
 include/uapi/linux/gpio.h |  2 ++
 3 files changed, 54 insertions(+), 10 deletions(-)

diff --git a/drivers/gpio/gpiolib.c b/drivers/gpio/gpiolib.c
index 24bdfdd26b85..0ac0a250b17a 100644
--- a/drivers/gpio/gpiolib.c
+++ b/drivers/gpio/gpiolib.c
@@ -424,6 +424,7 @@ struct linehandle_state {
 	GPIOHANDLE_REQUEST_ACTIVE_LOW | \
 	GPIOHANDLE_REQUEST_BIAS_PULL_UP | \
 	GPIOHANDLE_REQUEST_BIAS_PULL_DOWN | \
+	GPIOHANDLE_REQUEST_BIAS_DISABLE | \
 	GPIOHANDLE_REQUEST_OPEN_DRAIN | \
 	GPIOHANDLE_REQUEST_OPEN_SOURCE)
 
@@ -555,12 +556,21 @@ static int linehandle_create(struct gpio_device *gdev, void __user *ip)
 	     (lflags & GPIOHANDLE_REQUEST_OPEN_SOURCE)))
 		return -EINVAL;
 
-	/* PULL_UP and PULL_DOWN flags only make sense for input mode. */
+	/* Bias flags only allowed for input mode. */
 	if (!(lflags & GPIOHANDLE_REQUEST_INPUT) &&
-	    ((lflags & GPIOHANDLE_REQUEST_BIAS_PULL_UP) ||
+	    ((lflags & GPIOHANDLE_REQUEST_BIAS_DISABLE) ||
+	     (lflags & GPIOHANDLE_REQUEST_BIAS_PULL_UP) ||
 	     (lflags & GPIOHANDLE_REQUEST_BIAS_PULL_DOWN)))
 		return -EINVAL;
 
+	/* Only one bias flag can be set. */
+	if (((lflags & GPIOHANDLE_REQUEST_BIAS_DISABLE) &&
+	     (lflags & (GPIOHANDLE_REQUEST_BIAS_PULL_DOWN |
+			GPIOHANDLE_REQUEST_BIAS_PULL_UP))) ||
+	    ((lflags & GPIOHANDLE_REQUEST_BIAS_PULL_DOWN) &&
+	     (lflags & GPIOHANDLE_REQUEST_BIAS_PULL_UP)))
+		return -EINVAL;
+
 	lh = kzalloc(sizeof(*lh), GFP_KERNEL);
 	if (!lh)
 		return -ENOMEM;
@@ -601,6 +611,8 @@ static int linehandle_create(struct gpio_device *gdev, void __user *ip)
 			set_bit(FLAG_OPEN_DRAIN, &desc->flags);
 		if (lflags & GPIOHANDLE_REQUEST_OPEN_SOURCE)
 			set_bit(FLAG_OPEN_SOURCE, &desc->flags);
+		if (lflags & GPIOHANDLE_REQUEST_BIAS_DISABLE)
+			set_bit(FLAG_BIAS_DISABLE, &desc->flags);
 		if (lflags & GPIOHANDLE_REQUEST_BIAS_PULL_DOWN)
 			set_bit(FLAG_PULL_DOWN, &desc->flags);
 		if (lflags & GPIOHANDLE_REQUEST_BIAS_PULL_UP)
@@ -925,6 +937,14 @@ static int lineevent_create(struct gpio_device *gdev, void __user *ip)
 	    (lflags & GPIOHANDLE_REQUEST_OPEN_SOURCE))
 		return -EINVAL;
 
+	/* Only one bias flag can be set. */
+	if (((lflags & GPIOHANDLE_REQUEST_BIAS_DISABLE) &&
+	     (lflags & (GPIOHANDLE_REQUEST_BIAS_PULL_DOWN |
+			GPIOHANDLE_REQUEST_BIAS_PULL_UP))) ||
+	    ((lflags & GPIOHANDLE_REQUEST_BIAS_PULL_DOWN) &&
+	     (lflags & GPIOHANDLE_REQUEST_BIAS_PULL_UP)))
+		return -EINVAL;
+
 	le = kzalloc(sizeof(*le), GFP_KERNEL);
 	if (!le)
 		return -ENOMEM;
@@ -951,6 +971,8 @@ static int lineevent_create(struct gpio_device *gdev, void __user *ip)
 
 	if (lflags & GPIOHANDLE_REQUEST_ACTIVE_LOW)
 		set_bit(FLAG_ACTIVE_LOW, &desc->flags);
+	if (lflags & GPIOHANDLE_REQUEST_BIAS_DISABLE)
+		set_bit(FLAG_BIAS_DISABLE, &desc->flags);
 	if (lflags & GPIOHANDLE_REQUEST_BIAS_PULL_DOWN)
 		set_bit(FLAG_PULL_DOWN, &desc->flags);
 	if (lflags & GPIOHANDLE_REQUEST_BIAS_PULL_UP)
@@ -1108,6 +1130,8 @@ static long gpio_ioctl(struct file *filp, unsigned int cmd, unsigned long arg)
 		if (test_bit(FLAG_OPEN_SOURCE, &desc->flags))
 			lineinfo.flags |= (GPIOLINE_FLAG_OPEN_SOURCE |
 					   GPIOLINE_FLAG_IS_OUT);
+		if (test_bit(FLAG_BIAS_DISABLE, &desc->flags))
+			lineinfo.flags |= GPIOLINE_FLAG_BIAS_DISABLE;
 		if (test_bit(FLAG_PULL_DOWN, &desc->flags))
 			lineinfo.flags |= GPIOLINE_FLAG_BIAS_PULL_DOWN;
 		if (test_bit(FLAG_PULL_UP, &desc->flags))
@@ -2806,6 +2830,7 @@ static bool gpiod_free_commit(struct gpio_desc *desc)
 		clear_bit(FLAG_OPEN_SOURCE, &desc->flags);
 		clear_bit(FLAG_PULL_UP, &desc->flags);
 		clear_bit(FLAG_PULL_DOWN, &desc->flags);
+		clear_bit(FLAG_BIAS_DISABLE, &desc->flags);
 		clear_bit(FLAG_IS_HOGGED, &desc->flags);
 		ret = true;
 	}
@@ -2932,6 +2957,7 @@ static int gpio_set_config(struct gpio_chip *gc, unsigned offset,
 	unsigned arg;
 
 	switch (mode) {
+	case PIN_CONFIG_BIAS_DISABLE:
 	case PIN_CONFIG_BIAS_PULL_DOWN:
 	case PIN_CONFIG_BIAS_PULL_UP:
 		arg = 1;
@@ -2945,6 +2971,26 @@ static int gpio_set_config(struct gpio_chip *gc, unsigned offset,
 	return gc->set_config ? gc->set_config(gc, offset, config) : -ENOTSUPP;
 }
 
+static int gpio_set_bias(struct gpio_chip *chip, struct gpio_desc *desc)
+{
+	int bias = 0;
+	int ret = 0;
+
+	if (test_bit(FLAG_BIAS_DISABLE, &desc->flags))
+		bias = PIN_CONFIG_BIAS_DISABLE;
+	else if (test_bit(FLAG_PULL_UP, &desc->flags))
+		bias = PIN_CONFIG_BIAS_PULL_UP;
+	else if (test_bit(FLAG_PULL_DOWN, &desc->flags))
+		bias = PIN_CONFIG_BIAS_PULL_DOWN;
+
+	if (bias) {
+		ret = gpio_set_config(chip, gpio_chip_hwgpio(desc), bias);
+		if (ret != -ENOTSUPP)
+			return ret;
+	}
+	return 0;
+}
+
 /**
  * gpiod_direction_input - set the GPIO direction to input
  * @desc:	GPIO to set to input
@@ -2989,15 +3035,10 @@ int gpiod_direction_input(struct gpio_desc *desc)
 			   __func__);
 		return -EIO;
 	}
-	if (ret == 0)
+	if (ret == 0) {
 		clear_bit(FLAG_IS_OUT, &desc->flags);
-
-	if (test_bit(FLAG_PULL_UP, &desc->flags))
-		gpio_set_config(chip, gpio_chip_hwgpio(desc),
-				PIN_CONFIG_BIAS_PULL_UP);
-	else if (test_bit(FLAG_PULL_DOWN, &desc->flags))
-		gpio_set_config(chip, gpio_chip_hwgpio(desc),
-				PIN_CONFIG_BIAS_PULL_DOWN);
+		ret = gpio_set_bias(chip, desc);
+	}
 
 	trace_gpio_direction(desc_to_gpio(desc), 1, ret);
 
diff --git a/drivers/gpio/gpiolib.h b/drivers/gpio/gpiolib.h
index b8b10a409c7b..ca9bc1e4803c 100644
--- a/drivers/gpio/gpiolib.h
+++ b/drivers/gpio/gpiolib.h
@@ -110,6 +110,7 @@ struct gpio_desc {
 #define FLAG_TRANSITORY 12	/* GPIO may lose value in sleep or reset */
 #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 */
 
 	/* Connection label */
 	const char		*label;
diff --git a/include/uapi/linux/gpio.h b/include/uapi/linux/gpio.h
index 39e6c7854d63..7cc21c3b0839 100644
--- a/include/uapi/linux/gpio.h
+++ b/include/uapi/linux/gpio.h
@@ -35,6 +35,7 @@ struct gpiochip_info {
 #define GPIOLINE_FLAG_OPEN_SOURCE	(1UL << 4)
 #define GPIOLINE_FLAG_BIAS_PULL_UP	(1UL << 5)
 #define GPIOLINE_FLAG_BIAS_PULL_DOWN	(1UL << 6)
+#define GPIOLINE_FLAG_BIAS_DISABLE	(1UL << 7)
 
 /**
  * struct gpioline_info - Information about a certain GPIO line
@@ -66,6 +67,7 @@ struct gpioline_info {
 #define GPIOHANDLE_REQUEST_OPEN_SOURCE	(1UL << 4)
 #define GPIOHANDLE_REQUEST_BIAS_PULL_UP	(1UL << 5)
 #define GPIOHANDLE_REQUEST_BIAS_PULL_DOWN	(1UL << 6)
+#define GPIOHANDLE_REQUEST_BIAS_DISABLE	(1UL << 7)
 
 /**
  * struct gpiohandle_request - Information about a GPIO handle request
-- 
2.23.0


  parent reply	other threads:[~2019-11-05  2:05 UTC|newest]

Thread overview: 26+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-11-05  2:04 [PATCH v6 0/7] gpio: expose line bias flags to userspace Kent Gibson
2019-11-05  2:04 ` [PATCH v6 1/7] gpio: expose pull-up/pull-down line " Kent Gibson
2019-11-05  2:04 ` [PATCH v6 2/7] gpiolib: add support for pull up/down to lineevent_create Kent Gibson
2019-11-05  2:04 ` Kent Gibson [this message]
2019-11-05  2:04 ` [PATCH v6 4/7] gpiolib: add support for biasing output lines Kent Gibson
2019-11-06 19:39   ` Drew Fustini
2019-11-06 23:56     ` Kent Gibson
2019-11-05  2:04 ` [PATCH v6 5/7] gpio: mockup: add set_config to support pull up/down Kent Gibson
2019-11-05  2:04 ` [PATCH v6 6/7] gpiolib: move validation of line handle flags into helper function Kent Gibson
2019-11-05  2:04 ` [PATCH v6 7/7] gpio: add new SET_CONFIG ioctl() to gpio chardev Kent Gibson
2019-11-05 15:05 ` [PATCH v6 0/7] gpio: expose line bias flags to userspace Bartosz Golaszewski
2019-11-07  8:10   ` Linus Walleij
2019-11-05 15:26 ` Kent Gibson
2019-11-05 16:24   ` Bartosz Golaszewski
2019-11-05 21:07     ` Bartosz Golaszewski
2019-11-06  6:48       ` Kent Gibson
2019-11-06 13:59         ` Bartosz Golaszewski
2019-11-06 16:58           ` Kent Gibson
2019-11-06 17:06             ` Bartosz Golaszewski
2019-11-06 23:20               ` Kent Gibson
2019-11-07 10:39             ` Kent Gibson
2019-11-07 11:28               ` Bartosz Golaszewski
2019-11-07 12:18                 ` Kent Gibson
2019-11-05 23:15     ` Kent Gibson
2019-11-07 17:57 ` Bartosz Golaszewski
2020-04-15 14:03 ` boards to test gpio line bias flags? Drew Fustini

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