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>

2 files changed, 184 insertions, 2 deletions

diff --git a/drivers/gpio/gpio-uclass.c b/drivers/gpio/gpio-uclass.c
index 0a4d9e4..a69bbd2 100644
--- a/drivers/gpio/gpio-uclass.c
+++ b/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)
 {
diff --git a/drivers/gpio/sandbox.c b/drivers/gpio/sandbox.c
index 53c80d5..d564c25 100644
--- a/drivers/gpio/sandbox.c
+++ b/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)