dm: gpio: Add better functions to request GPIOs

At present U-Boot sort-of supports the standard way of reading GPIOs from
device tree nodes, but the support is incomplete, a bit clunky and only
works for GPIO bindings where #gpio-cells is 2.

Add new functions to request GPIOs, taking full account of the device
tree binding. These permit requesting a GPIO with a simple call like:

   gpio_request_by_name(dev, "cd-gpios", 0, &desc, GPIOD_IS_IN);

This will request the GPIO, looking at the device's node which might be
this, for example:

   cd-gpios = <&gpio TEGRA_GPIO(B, 3) GPIO_ACTIVE_LOW>;

The GPIO will be set to input mode in this case and polarity will be
honoured by the GPIO calls.

It is also possible to request and free a list of GPIOs.

Signed-off-by: Simon Glass <sjg@chromium.org>

drivers/gpio/gpio-uclass.c

@@ -12,6 +12,8 @@
 #include <asm/gpio.h>
 #include <linux/ctype.h>
 
+DECLARE_GLOBAL_DATA_PTR;
+
 /**
  * gpio_to_device() - Convert global GPIO number to device, number
  *
@@ -92,8 +94,8 @@ int gpio_lookup_name(const char *name, struct udevice **devp,
 	return 0;
 }
 
-int gpio_find_and_xlate(struct gpio_desc *desc,
-			struct fdtdec_phandle_args *args)
+static int gpio_find_and_xlate(struct gpio_desc *desc,
+			       struct fdtdec_phandle_args *args)
 {
 	struct dm_gpio_ops *ops = gpio_get_ops(desc->dev);
 
@@ -132,6 +134,17 @@ static int dm_gpio_request(struct gpio_desc *desc, const char *label)
 	return 0;
 }
 
+static int dm_gpio_requestf(struct gpio_desc *desc, const char *fmt, ...)
+{
+	va_list args;
+	char buf[40];
+
+	va_start(args, fmt);
+	vscnprintf(buf, sizeof(buf), fmt, args);
+	va_end(args);
+	return dm_gpio_request(desc, buf);
+}
+
 /**
  * gpio_request() - [COMPAT] Request GPIO
  * gpio:	GPIO number
@@ -501,6 +514,155 @@ unsigned gpio_get_values_as_int(const int *gpio_num_array)
 	return vector;
 }
 
+static int _gpio_request_by_name_nodev(const void *blob, int node,
+				       const char *list_name, int index,
+				       struct gpio_desc *desc, int flags,
+				       bool add_index)
+{
+	struct fdtdec_phandle_args args;
+	int ret;
+
+	desc->dev = NULL;
+	desc->offset = 0;
+	ret = fdtdec_parse_phandle_with_args(blob, node, list_name,
+					     "#gpio-cells", 0, index, &args);
+	if (ret) {
+		debug("%s: fdtdec_parse_phandle_with_args failed\n", __func__);
+		goto err;
+	}
+
+	ret = uclass_get_device_by_of_offset(UCLASS_GPIO, args.node,
+					     &desc->dev);
+	if (ret) {
+		debug("%s: uclass_get_device_by_of_offset failed\n", __func__);
+		goto err;
+	}
+	ret = gpio_find_and_xlate(desc, &args);
+	if (ret) {
+		debug("%s: gpio_find_and_xlate failed\n", __func__);
+		goto err;
+	}
+	ret = dm_gpio_requestf(desc, add_index ? "%s.%s%d" : "%s.%s",
+			       fdt_get_name(blob, node, NULL),
+			       list_name, index);
+	if (ret) {
+		debug("%s: dm_gpio_requestf failed\n", __func__);
+		goto err;
+	}
+	ret = dm_gpio_set_dir_flags(desc, flags | desc->flags);
+	if (ret) {
+		debug("%s: dm_gpio_set_dir failed\n", __func__);
+		goto err;
+	}
+
+	return 0;
+err:
+	debug("%s: Node '%s', property '%s', failed to request GPIO index %d: %d\n",
+	      __func__, fdt_get_name(blob, node, NULL), list_name, index, ret);
+	return ret;
+}
+
+int gpio_request_by_name_nodev(const void *blob, int node,
+			       const char *list_name, int index,
+			       struct gpio_desc *desc, int flags)
+{
+	return _gpio_request_by_name_nodev(blob, node, list_name, index, desc,
+					   flags, index > 0);
+}
+
+int gpio_request_by_name(struct udevice *dev,  const char *list_name, int index,
+			 struct gpio_desc *desc, int flags)
+{
+	/*
+	 * This isn't ideal since we don't use dev->name in the debug()
+	 * calls in gpio_request_by_name(), but we can do this until
+	 * gpio_request_by_name_nodev() can be dropped.
+	 */
+	return gpio_request_by_name_nodev(gd->fdt_blob, dev->of_offset,
+					  list_name, index, desc, flags);
+}
+
+int gpio_request_list_by_name_nodev(const void *blob, int node,
+				    const char *list_name,
+				    struct gpio_desc *desc, int max_count,
+				    int flags)
+{
+	int count;
+	int ret;
+
+	for (count = 0; ; count++) {
+		if (count >= max_count) {
+			ret = -ENOSPC;
+			goto err;
+		}
+		ret = _gpio_request_by_name_nodev(blob, node, list_name, count,
+						  &desc[count], flags, true);
+		if (ret == -ENOENT)
+			break;
+		else if (ret)
+			goto err;
+	}
+
+	/* We ran out of GPIOs in the list */
+	return count;
+
+err:
+	gpio_free_list_nodev(desc, count - 1);
+
+	return ret;
+}
+
+int gpio_request_list_by_name(struct udevice *dev, const char *list_name,
+			      struct gpio_desc *desc, int max_count,
+			      int flags)
+{
+	/*
+	 * This isn't ideal since we don't use dev->name in the debug()
+	 * calls in gpio_request_by_name(), but we can do this until
+	 * gpio_request_list_by_name_nodev() can be dropped.
+	 */
+	return gpio_request_list_by_name_nodev(gd->fdt_blob, dev->of_offset,
+					       list_name, desc, max_count,
+					       flags);
+}
+
+int gpio_get_list_count(struct udevice *dev, const char *list_name)
+{
+	int ret;
+
+	ret = fdtdec_parse_phandle_with_args(gd->fdt_blob, dev->of_offset,
+					     list_name, "#gpio-cells", 0, -1,
+					     NULL);
+	if (ret) {
+		debug("%s: Node '%s', property '%s', GPIO count failed: %d\n",
+		      __func__, dev->name, list_name, ret);
+	}
+
+	return ret;
+}
+
+int dm_gpio_free(struct udevice *dev, struct gpio_desc *desc)
+{
+	/* For now, we don't do any checking of dev */
+	return _dm_gpio_free(desc->dev, desc->offset);
+}
+
+int gpio_free_list(struct udevice *dev, struct gpio_desc *desc, int count)
+{
+	int i;
+
+	/* For now, we don't do any checking of dev */
+	for (i = 0; i < count; i++)
+		dm_gpio_free(dev, &desc[i]);
+
+	return 0;
+}
+
+int gpio_free_list_nodev(struct gpio_desc *desc, int count)
+{
+	return gpio_free_list(NULL, desc, count);
+}
+
 /* We need to renumber the GPIOs when any driver is probed/removed */
 static int gpio_renumber(struct udevice *removed_dev)
 {

drivers/gpio/sandbox.c

@@ -8,6 +8,7 @@
 #include <fdtdec.h>
 #include <malloc.h>
 #include <asm/gpio.h>
+#include <dt-bindings/gpio/gpio.h>
 
 DECLARE_GLOBAL_DATA_PTR;
 
@@ -130,12 +131,31 @@ static int sb_gpio_get_function(struct udevice *dev, unsigned offset)
 	return GPIOF_INPUT;
 }
 
+static int sb_gpio_xlate(struct udevice *dev, struct gpio_desc *desc,
+			 struct fdtdec_phandle_args *args)
+{
+	desc->offset = args->args[0];
+	if (args->args_count < 2)
+		return 0;
+	if (args->args[1] & GPIO_ACTIVE_LOW)
+		desc->flags |= GPIOD_ACTIVE_LOW;
+	if (args->args[1] & 2)
+		desc->flags |= GPIOD_IS_IN;
+	if (args->args[1] & 4)
+		desc->flags |= GPIOD_IS_OUT;
+	if (args->args[1] & 8)
+		desc->flags |= GPIOD_IS_OUT_ACTIVE;
+
+	return 0;
+}
+
 static const struct dm_gpio_ops gpio_sandbox_ops = {
 	.direction_input	= sb_gpio_direction_input,
 	.direction_output	= sb_gpio_direction_output,
 	.get_value		= sb_gpio_get_value,
 	.set_value		= sb_gpio_set_value,
 	.get_function		= sb_gpio_get_function,
+	.xlate			= sb_gpio_xlate,
 };
 
 static int sandbox_gpio_ofdata_to_platdata(struct udevice *dev)

include/asm-generic/gpio.h

@@ -111,6 +111,18 @@ struct gpio_desc {
 	 */
 };
 
+/**
+ * dm_gpio_is_valid() - Check if a GPIO is gpio_is_valie
+ *
+ * @desc:	GPIO description containing device, offset and flags,
+ *		previously returned by gpio_request_by_name()
+ * @return true if valid, false if not
+ */
+static inline bool dm_gpio_is_valid(struct gpio_desc *desc)
+{
+	return desc->dev != NULL;
+}
+
 /**
  * gpio_get_status() - get the current GPIO status as a string
  *
@@ -313,4 +325,191 @@ int gpio_lookup_name(const char *name, struct udevice **devp,
  */
 unsigned gpio_get_values_as_int(const int *gpio_list);
 
+/**
+ * gpio_request_by_name() - Locate and request a GPIO by name
+ *
+ * This operates by looking up the given list name in the device (device
+ * tree property) and requesting the GPIO for use. The property must exist
+ * in @dev's node.
+ *
+ * Use @flags to specify whether the GPIO should be an input or output. In
+ * principle this can also come from the device tree binding but most
+ * bindings don't provide this information. Specifically, when the GPIO uclass
+ * calls the xlate() method, it can return default flags, which are then
+ * ORed with this @flags.
+ *
+ * If we find that requesting the GPIO is not always needed we could add a
+ * new function or a new GPIOD_NO_REQUEST flag.
+ *
+ * At present driver model has no reference counting so if one device
+ * requests a GPIO which subsequently is unbound, the @desc->dev pointer
+ * will be invalid. However this will only happen if the GPIO device is
+ * unbound, not if it is removed, so this seems like a reasonable limitation
+ * for now. There is no real use case for unbinding drivers in normal
+ * operation.
+ *
+ * The device tree binding is doc/device-tree-bindings/gpio/gpio.txt in
+ * generate terms and each specific device may add additional details in
+ * a binding file in the same directory.
+ *
+ * @dev:	Device requesting the GPIO
+ * @list_name:	Name of GPIO list (e.g. "board-id-gpios")
+ * @index:	Index number of the GPIO in that list use request (0=first)
+ * @desc:	Returns GPIO description information. If there is no such
+ *		GPIO, dev->dev will be NULL.
+ * @flags:	Indicates the GPIO input/output settings (GPIOD_...)
+ * @return 0 if OK, -ENOENT if the GPIO does not exist, -EINVAL if there is
+ * something wrong with the list, or other -ve for another error (e.g.
+ * -EBUSY if a GPIO was already requested)
+ */
+int gpio_request_by_name(struct udevice *dev, const char *list_name,
+			 int index, struct gpio_desc *desc, int flags);
+
+/**
+ * gpio_request_list_by_name() - Request a list of GPIOs
+ *
+ * Reads all the GPIOs from a list and requetss them. See
+ * gpio_request_by_name() for additional details. Lists should not be
+ * misused to hold unrelated or optional GPIOs. They should only be used
+ * for things like parallel data lines. A zero phandle terminates the list
+ * the list.
+ *
+ * This function will either succeed, and request all GPIOs in the list, or
+ * fail and request none (it will free already-requested GPIOs in case of
+ * an error part-way through).
+ *
+ * @dev:	Device requesting the GPIO
+ * @list_name:	Name of GPIO list (e.g. "board-id-gpios")
+ * @desc_list:	Returns a list of GPIO description information
+ * @max_count:	Maximum number of GPIOs to return (@desc_list must be at least
+ *		this big)
+ * @flags:	Indicates the GPIO input/output settings (GPIOD_...)
+ * @return number of GPIOs requested, or -ve on error
+ */
+int gpio_request_list_by_name(struct udevice *dev, const char *list_name,
+			      struct gpio_desc *desc_list, int max_count,
+			      int flags);
+
+/**
+ * gpio_get_list_count() - Returns the number of GPIOs in a list
+ *
+ * Counts the GPIOs in a list. See gpio_request_by_name() for additional
+ * details.
+ *
+ * @dev:	Device requesting the GPIO
+ * @list_name:	Name of GPIO list (e.g. "board-id-gpios")
+ * @return number of GPIOs (0 for an empty property) or -ENOENT if the list
+ * does not exist
+ */
+int gpio_get_list_count(struct udevice *dev, const char *list_name);
+
+/**
+ * gpio_request_by_name_nodev() - request GPIOs without a device
+ *
+ * This is a version of gpio_request_list_by_name() that does not use a
+ * device. Avoid it unless the caller is not yet using driver model
+ */
+int gpio_request_by_name_nodev(const void *blob, int node,
+			       const char *list_name,
+			       int index, struct gpio_desc *desc, int flags);
+
+/**
+ * gpio_request_list_by_name_nodev() - request GPIOs without a device
+ *
+ * This is a version of gpio_request_list_by_name() that does not use a
+ * device. Avoid it unless the caller is not yet using driver model
+ */
+int gpio_request_list_by_name_nodev(const void *blob, int node,
+				    const char *list_name,
+				    struct gpio_desc *desc_list, int max_count,
+				    int flags);
+
+/**
+ * dm_gpio_free() - Free a single GPIO
+ *
+ * This frees a single GPIOs previously returned from gpio_request_by_name().
+ *
+ * @dev:	Device which requested the GPIO
+ * @desc:	GPIO to free
+ * @return 0 if OK, -ve on error
+ */
+int dm_gpio_free(struct udevice *dev, struct gpio_desc *desc);
+
+/**
+ * gpio_free_list() - Free a list of GPIOs
+ *
+ * This frees a list of GPIOs previously returned from
+ * gpio_request_list_by_name().
+ *
+ * @dev:	Device which requested the GPIOs
+ * @desc:	List of GPIOs to free
+ * @count:	Number of GPIOs in the list
+ * @return 0 if OK, -ve on error
+ */
+int gpio_free_list(struct udevice *dev, struct gpio_desc *desc, int count);
+
+/**
+ * gpio_free_list_nodev() - free GPIOs without a device
+ *
+ * This is a version of gpio_free_list() that does not use a
+ * device. Avoid it unless the caller is not yet using driver model
+ */
+int gpio_free_list_nodev(struct gpio_desc *desc, int count);
+
+/**
+ * dm_gpio_get_value() - Get the value of a GPIO
+ *
+ * This is the driver model version of the existing gpio_get_value() function
+ * and should be used instead of that.
+ *
+ * For now, these functions have a dm_ prefix since they conflict with
+ * existing names.
+ *
+ * @desc:	GPIO description containing device, offset and flags,
+ *		previously returned by gpio_request_by_name()
+ * @return GPIO value (0 for inactive, 1 for active) or -ve on error
+ */
+int dm_gpio_get_value(struct gpio_desc *desc);
+
+int dm_gpio_set_value(struct gpio_desc *desc, int value);
+
+/**
+ * dm_gpio_set_dir() - Set the direction for a GPIO
+ *
+ * This sets up the direction according tot the provided flags. It will do
+ * nothing unless the direction is actually specified.
+ *
+ * @desc:	GPIO description containing device, offset and flags,
+ *		previously returned by gpio_request_by_name()
+ * @return 0 if OK, -ve on error
+ */
+int dm_gpio_set_dir(struct gpio_desc *desc);
+
+/**
+ * dm_gpio_set_dir_flags() - Set direction using specific flags
+ *
+ * This is like dm_gpio_set_dir() except that the flags value is provided
+ * instead of being used from desc->flags. This is needed because in many
+ * cases the GPIO description does not include direction information.
+ * Note that desc->flags is updated by this function.
+ *
+ * @desc:	GPIO description containing device, offset and flags,
+ *		previously returned by gpio_request_by_name()
+ * @flags:	New flags to use
+ * @return 0 if OK, -ve on error, in which case desc->flags is not updated
+ */
+int dm_gpio_set_dir_flags(struct gpio_desc *desc, ulong flags);
+
+/**
+ * gpio_get_number() - Get the global GPIO number of a GPIO
+ *
+ * This should only be used for debugging or interest. It returns the nummber
+ * that should be used for gpio_get_value() etc. to access this GPIO.
+ *
+ * @desc:	GPIO description containing device, offset and flags,
+ *		previously returned by gpio_request_by_name()
+ * @return GPIO number, or -ve if not found
+ */
+int gpio_get_number(struct gpio_desc *desc);
+
 #endif	/* _ASM_GENERIC_GPIO_H_ */

test/dm/gpio.c

@@ -174,5 +174,72 @@ static int dm_test_gpio_leak(struct dm_test_state *dms)
 
 	return 0;
 }
-
 DM_TEST(dm_test_gpio_leak, DM_TESTF_SCAN_PDATA | DM_TESTF_SCAN_FDT);
+
+/* Test that we can find GPIOs using phandles */
+static int dm_test_gpio_phandles(struct dm_test_state *dms)
+{
+	struct gpio_desc desc, desc_list[8], desc_list2[8];
+	struct udevice *dev, *gpio_a, *gpio_b;
+
+	ut_assertok(uclass_get_device(UCLASS_TEST_FDT, 0, &dev));
+	ut_asserteq_str("a-test", dev->name);
+
+	ut_assertok(gpio_request_by_name(dev, "test-gpios", 1, &desc, 0));
+	ut_assertok(uclass_get_device(UCLASS_GPIO, 1, &gpio_a));
+	ut_assertok(uclass_get_device(UCLASS_GPIO, 2, &gpio_b));
+	ut_asserteq_str("base-gpios", gpio_a->name);
+	ut_asserteq(true, !!device_active(gpio_a));
+	ut_asserteq_ptr(gpio_a, desc.dev);
+	ut_asserteq(4, desc.offset);
+	/* GPIOF_INPUT is the sandbox GPIO driver default */
+	ut_asserteq(GPIOF_INPUT, gpio_get_function(gpio_a, 4, NULL));
+	ut_assertok(dm_gpio_free(dev, &desc));
+
+	ut_asserteq(-ENOENT, gpio_request_by_name(dev, "test-gpios", 3, &desc,
+						  0));
+	ut_asserteq_ptr(NULL, desc.dev);
+	ut_asserteq(desc.offset, 0);
+	ut_asserteq(-ENOENT, gpio_request_by_name(dev, "test-gpios", 5, &desc,
+						  0));
+
+	/* Last GPIO is ignord as it comes after <0> */
+	ut_asserteq(3, gpio_request_list_by_name(dev, "test-gpios", desc_list,
+						 ARRAY_SIZE(desc_list), 0));
+	ut_asserteq(-EBUSY, gpio_request_list_by_name(dev, "test-gpios",
+						      desc_list2,
+						      ARRAY_SIZE(desc_list2),
+						      0));
+	ut_assertok(gpio_free_list(dev, desc_list, 3));
+	ut_asserteq(3, gpio_request_list_by_name(dev,  "test-gpios", desc_list,
+						 ARRAY_SIZE(desc_list),
+						 GPIOD_IS_OUT |
+						 GPIOD_IS_OUT_ACTIVE));
+	ut_asserteq_ptr(gpio_a, desc_list[0].dev);
+	ut_asserteq(1, desc_list[0].offset);
+	ut_asserteq_ptr(gpio_a, desc_list[1].dev);
+	ut_asserteq(4, desc_list[1].offset);
+	ut_asserteq_ptr(gpio_b, desc_list[2].dev);
+	ut_asserteq(5, desc_list[2].offset);
+	ut_asserteq(1, dm_gpio_get_value(desc_list));
+	ut_assertok(gpio_free_list(dev, desc_list, 3));
+
+	ut_asserteq(6, gpio_request_list_by_name(dev, "test2-gpios", desc_list,
+						 ARRAY_SIZE(desc_list), 0));
+	/* This was set to output previously, so still will be */
+	ut_asserteq(GPIOF_OUTPUT, gpio_get_function(gpio_a, 1, NULL));
+
+	/* Active low should invert the input value */
+	ut_asserteq(GPIOF_INPUT, gpio_get_function(gpio_b, 6, NULL));
+	ut_asserteq(1, dm_gpio_get_value(&desc_list[2]));
+
+	ut_asserteq(GPIOF_INPUT, gpio_get_function(gpio_b, 7, NULL));
+	ut_asserteq(GPIOF_OUTPUT, gpio_get_function(gpio_b, 8, NULL));
+	ut_asserteq(0, dm_gpio_get_value(&desc_list[4]));
+	ut_asserteq(GPIOF_OUTPUT, gpio_get_function(gpio_b, 9, NULL));
+	ut_asserteq(1, dm_gpio_get_value(&desc_list[5]));
+
+
+	return 0;
+}
+DM_TEST(dm_test_gpio_phandles, DM_TESTF_SCAN_PDATA | DM_TESTF_SCAN_FDT);

test/dm/test.dts

@@ -22,6 +22,11 @@
 		ping-expect = <0>;
 		ping-add = <0>;
 		u-boot,dm-pre-reloc;
+		test-gpios = <&gpio_a 1>, <&gpio_a 4>, <&gpio_b 5 0 3 2 1>,
+			<0>, <&gpio_a 12>;
+		test2-gpios = <&gpio_a 1>, <&gpio_a 4>, <&gpio_b 6 1 3 2 1>,
+			<&gpio_b 7 2 3 2 1>, <&gpio_b 8 4 3 2 1>,
+			<&gpio_b 9 0xc 3 2 1>;
 	};
 
 	junk {
@@ -83,12 +88,16 @@
 
 	gpio_a: base-gpios {
 		compatible = "sandbox,gpio";
+		gpio-controller;
+		#gpio-cells = <1>;
 		gpio-bank-name = "a";
 		num-gpios = <20>;
 	};
 
-	extra-gpios {
+	gpio_b: extra-gpios {
 		compatible = "sandbox,gpio";
+		gpio-controller;
+		#gpio-cells = <5>;
 		gpio-bank-name = "b";
 		num-gpios = <10>;
 	};