[PATCH v3 0/2] gpio: Add a managed API

[PATCH v3 0/2] gpio: Add a managed API

[Pratyush Yadav]

Hi,

This is a re-submission of Jean-Jacques' earlier work in October last
year. It can be fount at [0]. The goal is to facilitate porting drivers
from the linux kernel. Most of the series will be about adding managed
API to existing infrastructure (GPIO, reset, regmap (already
submitted)).

This particular series is about GPIOs. It adds a managed API using the
API as Linux. To make it 100% compatible with linux, there is a small
deviation from u-boot's way of naming the gpio lists: the managed
equivalent of gpio_request_by_name(..,"blabla-gpios", ...) is
devm_gpiod_get_index(..., "blabla", ...)

Changes in v3:
- Add a blank line before return in devm_gpiod_get_index().
- Add Simon's Reviwed-by in both patches.

Changes in v2:
- The original series had a patch that checked for NULL pointers in the
  core GPIO functions. The checks were needed because of the addition of
  devm_gpiod_get_index_optional() which would return NULL when when no
  GPIO was assigned to the requested function. This is convenient for
  drivers that need to handle optional GPIOs.

  Simon argued that those should be behind a Kconfig option because of
  code size concerns. He also argued against implicit return in the
  macro that checked for the optional GPIOs.

  This submission removes the controversial patch so that base
  functionality can get merged.

  We still need to take a stance on who is responsible for the NULL
  check: the driver or the GPIO core? Do we want to trust drivers to
  take care of the NULL checks, or do we want to distrust them and make
  sure they don't send us anything bogus in the GPIO core. I will send a
  separate RFC of the NULL check patch and we can probably discuss the
  issue there.

[0] https://patchwork.ozlabs.org/project/uboot/cover/20191001115130.18886-1-jjhiblot at ti.com/

Jean-Jacques Hiblot (2):
  drivers: gpio: Add a managed API to get a GPIO from the device-tree
  test: gpio: Add tests for the managed API

 arch/sandbox/dts/test.dts  |  10 ++++
 drivers/gpio/gpio-uclass.c |  71 ++++++++++++++++++++++++++
 include/asm-generic/gpio.h |  47 +++++++++++++++++
 test/dm/gpio.c             | 102 +++++++++++++++++++++++++++++++++++++
 4 files changed, 230 insertions(+)

--
2.27.0

[PATCH v3 1/2] drivers: gpio: Add a managed API to get a GPIO from the device-tree

[Pratyush Yadav]

From: Jean-Jacques Hiblot <jjhiblot@ti.com>

Add managed functions to get a gpio from the devce-tree, based on a
property name (minus the '-gpios' suffix) and optionally an index.

When the device is unbound, the GPIO is automatically released and the
data structure is freed.

Signed-off-by: Jean-Jacques Hiblot <jjhiblot@ti.com>
Reviewed-by: Simon Glass <sjg@chromium.org>
Signed-off-by: Pratyush Yadav <p.yadav@ti.com>
---
 drivers/gpio/gpio-uclass.c | 71 ++++++++++++++++++++++++++++++++++++++
 include/asm-generic/gpio.h | 47 +++++++++++++++++++++++++
 2 files changed, 118 insertions(+)

diff --git a/drivers/gpio/gpio-uclass.c b/drivers/gpio/gpio-uclass.c
index 9eeab22eef..c460ebc63b 100644
--- a/drivers/gpio/gpio-uclass.c
+++ b/drivers/gpio/gpio-uclass.c
@@ -6,6 +6,8 @@
 #include <common.h>
 #include <dm.h>
 #include <log.h>
+#include <dm/devres.h>
+#include <dm/device_compat.h>
 #include <dm/device-internal.h>
 #include <dm/lists.h>
 #include <dm/uclass-internal.h>
@@ -1141,6 +1143,75 @@ int gpio_dev_request_index(struct udevice *dev, const char *nodename,
 				 flags, 0, dev);
 }

+static void devm_gpiod_release(struct udevice *dev, void *res)
+{
+	dm_gpio_free(dev, res);
+}
+
+static int devm_gpiod_match(struct udevice *dev, void *res, void *data)
+{
+	return res == data;
+}
+
+struct gpio_desc *devm_gpiod_get_index(struct udevice *dev, const char *id,
+				       unsigned int index, int flags)
+{
+	int rc;
+	struct gpio_desc *desc;
+	char *propname;
+	static const char suffix[] = "-gpios";
+
+	propname = malloc(strlen(id) + sizeof(suffix));
+	if (!propname) {
+		rc = -ENOMEM;
+		goto end;
+	}
+
+	strcpy(propname, id);
+	strcat(propname, suffix);
+
+	desc = devres_alloc(devm_gpiod_release, sizeof(struct gpio_desc),
+			    __GFP_ZERO);
+	if (unlikely(!desc)) {
+		rc = -ENOMEM;
+		goto end;
+	}
+
+	rc = gpio_request_by_name(dev, propname, index, desc, flags);
+
+end:
+	if (propname)
+		free(propname);
+
+	if (rc)
+		return ERR_PTR(rc);
+
+	devres_add(dev, desc);
+
+	return desc;
+}
+
+struct gpio_desc *devm_gpiod_get_index_optional(struct udevice *dev,
+						const char *id,
+						unsigned int index,
+						int flags)
+{
+	struct gpio_desc *desc = devm_gpiod_get_index(dev, id, index, flags);
+
+	if (IS_ERR(desc))
+		return NULL;
+
+	return desc;
+}
+
+void devm_gpiod_put(struct udevice *dev, struct gpio_desc *desc)
+{
+	int rc;
+
+	rc = devres_release(dev, devm_gpiod_release, devm_gpiod_match, desc);
+	WARN_ON(rc);
+}
+
 static int gpio_post_bind(struct udevice *dev)
 {
 	struct udevice *child;
diff --git a/include/asm-generic/gpio.h b/include/asm-generic/gpio.h
index e16c2f31d9..76e0e902c4 100644
--- a/include/asm-generic/gpio.h
+++ b/include/asm-generic/gpio.h
@@ -674,4 +674,51 @@ int dm_gpio_get_dir_flags(struct gpio_desc *desc, ulong *flags);
  */
 int gpio_get_number(const struct gpio_desc *desc);

+/**
+ * devm_gpiod_get_index - Resource-managed gpiod_get()
+ * @dev:	GPIO consumer
+ * @con_id:	function within the GPIO consumer
+ * @index:	index of the GPIO to obtain in the consumer
+ * @flags:	optional GPIO initialization flags
+ *
+ * Managed gpiod_get(). GPIO descriptors returned from this function are
+ * automatically disposed on driver detach.
+ * Return the GPIO descriptor corresponding to the function con_id of device
+ * dev, -ENOENT if no GPIO has been assigned to the requested function, or
+ * another IS_ERR() code if an error occurred while trying to acquire the GPIO.
+ */
+struct gpio_desc *devm_gpiod_get_index(struct udevice *dev, const char *id,
+				       unsigned int index, int flags);
+
+#define devm_gpiod_get(dev, id, flags) devm_gpiod_get_index(dev, id, 0, flags)
+/**
+ * gpiod_get_optional - obtain an optional GPIO for a given GPIO function
+ * @dev: GPIO consumer, can be NULL for system-global GPIOs
+ * @con_id: function within the GPIO consumer
+ * @index:	index of the GPIO to obtain in the consumer
+ * @flags: optional GPIO initialization flags
+ *
+ * This is equivalent to devm_gpiod_get(), except that when no GPIO was
+ * assigned to the requested function it will return NULL. This is convenient
+ * for drivers that need to handle optional GPIOs.
+ */
+struct gpio_desc *devm_gpiod_get_index_optional(struct udevice *dev,
+						const char *id,
+						unsigned int index,
+						int flags);
+
+#define devm_gpiod_get_optional(dev, id, flags) \
+	devm_gpiod_get_index_optional(dev, id, 0, flags)
+
+/**
+ * devm_gpiod_put - Resource-managed gpiod_put()
+ * @dev:	GPIO consumer
+ * @desc:	GPIO descriptor to dispose of
+ *
+ * Dispose of a GPIO descriptor obtained with devm_gpiod_get() or
+ * devm_gpiod_get_index(). Normally this function will not be called as the GPIO
+ * will be disposed of by the resource management code.
+ */
+void devm_gpiod_put(struct udevice *dev, struct gpio_desc *desc);
+
 #endif	/* _ASM_GENERIC_GPIO_H_ */
--
2.27.0

[PATCH v3 2/2] test: gpio: Add tests for the managed API

[Pratyush Yadav]

From: Jean-Jacques Hiblot <jjhiblot@ti.com>

Add a test to verify that GPIOs can be acquired/released using the managed
API. Also check that the GPIOs are released when the consumer device is
removed.

Signed-off-by: Jean-Jacques Hiblot <jjhiblot@ti.com>
Reviewed-by: Simon Glass <sjg@chromium.org>
Signed-off-by: Pratyush Yadav <p.yadav@ti.com>
---
 arch/sandbox/dts/test.dts |  10 ++++
 test/dm/gpio.c            | 102 ++++++++++++++++++++++++++++++++++++++
 2 files changed, 112 insertions(+)

diff --git a/arch/sandbox/dts/test.dts b/arch/sandbox/dts/test.dts
index 5ce5e28476..a8618ccade 100644
--- a/arch/sandbox/dts/test.dts
+++ b/arch/sandbox/dts/test.dts
@@ -107,6 +107,9 @@
 			<&gpio_c 5 GPIO_IN>,
 			<&gpio_c 6 (GPIO_ACTIVE_LOW|GPIO_OUT|GPIO_OPEN_DRAIN)>,
 			<&gpio_c 7 (GPIO_ACTIVE_LOW|GPIO_OUT|GPIO_OPEN_SOURCE)>;
+		test4-gpios = <&gpio_a 14>, <&gpio_b 4 1 3 2 1>;
+		test5-gpios = <&gpio_a 19>;
+
 		int-value = <1234>;
 		uint-value = <(-1234)>;
 		int64-value = /bits/ 64 <0x1111222233334444>;
@@ -114,6 +117,13 @@
 		interrupts-extended = <&irq 3 0>;
 	};

+	another-test {
+		reg = <0 2>;
+		compatible = "denx,u-boot-fdt-test";
+		test4-gpios = <&gpio_a 14>, <&gpio_b 4 1 3 2 1>;
+		test5-gpios = <&gpio_a 19>;
+	};
+
 	junk {
 		reg = <1 1>;
 		compatible = "not,compatible";
diff --git a/test/dm/gpio.c b/test/dm/gpio.c
index b5ee4e4f87..40bea32b13 100644
--- a/test/dm/gpio.c
+++ b/test/dm/gpio.c
@@ -8,6 +8,7 @@
 #include <dm.h>
 #include <log.h>
 #include <malloc.h>
+#include <dm/device-internal.h>
 #include <dm/root.h>
 #include <dm/test.h>
 #include <dm/util.h>
@@ -385,3 +386,104 @@ static int dm_test_gpio_get_dir_flags(struct unit_test_state *uts)
 	return 0;
 }
 DM_TEST(dm_test_gpio_get_dir_flags, DM_TESTF_SCAN_PDATA | DM_TESTF_SCAN_FDT);
+
+/* Test that we can get/release GPIOs using managed API */
+static int dm_test_gpio_devm(struct unit_test_state *uts)
+{
+	static const u32 flags = GPIOD_IS_OUT | GPIOD_IS_OUT_ACTIVE;
+	struct gpio_desc *desc1, *desc2, *desc3, *desc_err;
+	struct udevice *dev;
+	struct udevice *dev2;
+
+	ut_assertok(uclass_get_device_by_name(UCLASS_TEST_FDT, "a-test",
+					      &dev));
+	ut_assertok(uclass_get_device_by_name(UCLASS_TEST_FDT, "another-test",
+					      &dev2));
+
+	/* Get 3 GPIOs from 'a-test' dev */
+	desc1 = devm_gpiod_get_index(dev, "test4", 0, flags);
+	ut_assert(!IS_ERR(desc1));
+	desc2 = devm_gpiod_get_index(dev, "test4", 1, flags);
+	ut_assert(!IS_ERR(desc2));
+	desc3 = devm_gpiod_get_index_optional(dev, "test5", 0, flags);
+	ut_assert(!IS_ERR(desc3));
+	ut_assert(desc3);
+
+	/*
+	 * Try get the same 3 GPIOs from 'a-test' and 'another-test' devices.
+	 * check that it fails
+	 */
+	desc_err = devm_gpiod_get_index(dev, "test4", 0, flags);
+	ut_asserteq(-EBUSY, PTR_ERR(desc_err));
+	desc_err = devm_gpiod_get_index(dev2, "test4", 0, flags);
+	ut_asserteq(-EBUSY, PTR_ERR(desc_err));
+	desc_err = devm_gpiod_get_index(dev, "test4", 1, flags);
+	ut_asserteq(-EBUSY, PTR_ERR(desc_err));
+	desc_err = devm_gpiod_get_index(dev2, "test4", 1, flags);
+	ut_asserteq(-EBUSY, PTR_ERR(desc_err));
+	desc_err = devm_gpiod_get_index_optional(dev, "test5", 0, flags);
+	ut_asserteq_ptr(NULL, desc_err);
+	desc_err = devm_gpiod_get_index_optional(dev2, "test5", 0, flags);
+	ut_asserteq_ptr(NULL, desc_err);
+
+	/* Try get GPIOs outside of the list */
+	desc_err = devm_gpiod_get_index(dev, "test4", 2, flags);
+	ut_assert(IS_ERR(desc_err));
+	desc_err = devm_gpiod_get_index_optional(dev, "test5", 1, flags);
+	ut_asserteq_ptr(NULL, desc_err);
+
+	/* Manipulate the GPIOs */
+	ut_assertok(dm_gpio_set_value(desc1, 1));
+	ut_asserteq(1, dm_gpio_get_value(desc1));
+	ut_assertok(dm_gpio_set_value(desc1, 0));
+	ut_asserteq(0, dm_gpio_get_value(desc1));
+
+	ut_assertok(dm_gpio_set_value(desc2, 1));
+	ut_asserteq(1, dm_gpio_get_value(desc2));
+	ut_assertok(dm_gpio_set_value(desc2, 0));
+	ut_asserteq(0, dm_gpio_get_value(desc2));
+
+	ut_assertok(dm_gpio_set_value(desc3, 1));
+	ut_asserteq(1, dm_gpio_get_value(desc3));
+	ut_assertok(dm_gpio_set_value(desc3, 0));
+	ut_asserteq(0, dm_gpio_get_value(desc3));
+
+	/* Check that the GPIO cannot be owned by more than one device */
+	desc_err = devm_gpiod_get_index(dev2, "test4", 0, flags);
+	ut_asserteq(-EBUSY, PTR_ERR(desc_err));
+	desc_err = devm_gpiod_get_index(dev2, "test4", 1, flags);
+	ut_asserteq(-EBUSY, PTR_ERR(desc_err));
+	desc_err = devm_gpiod_get_index_optional(dev2, "test5", 0, flags);
+	ut_asserteq_ptr(NULL, desc_err);
+
+	/*
+	 * Release one GPIO and check that we can get it back using
+	 * 'another-test' and then 'a-test'
+	 */
+	devm_gpiod_put(dev, desc2);
+	desc2 = devm_gpiod_get_index(dev2, "test4", 1, flags);
+	ut_assert(!IS_ERR(desc2));
+
+	devm_gpiod_put(dev2, desc2);
+	desc2 = devm_gpiod_get_index(dev, "test4", 1, flags);
+	ut_assert(!IS_ERR(desc2));
+
+	/* Release one GPIO before removing the 'a-test' dev. */
+	devm_gpiod_put(dev, desc2);
+	device_remove(dev, DM_REMOVE_NORMAL);
+
+	/* All the GPIOs must have been freed. We should be able to claim
+	 * them with the 'another-test' device.
+	 */
+	desc1 = devm_gpiod_get_index(dev2, "test4", 0, flags);
+	ut_assert(!IS_ERR(desc1));
+	desc2 = devm_gpiod_get_index(dev2, "test4", 1, flags);
+	ut_assert(!IS_ERR(desc2));
+	desc3 = devm_gpiod_get_index_optional(dev2, "test5", 0, flags);
+	ut_assert(!IS_ERR(desc3));
+	ut_assert(desc3);
+
+	device_remove(dev2, DM_REMOVE_NORMAL);
+	return 0;
+}
+DM_TEST(dm_test_gpio_devm, DM_TESTF_SCAN_PDATA | DM_TESTF_SCAN_FDT);
--
2.27.0