dm: demo: Add a simple GPIO demonstration

Add a new 'demo light' command which uses GPIOs to control imaginary lights.
Each light is assigned a bit number in the overall value. This provides an
example driver for using the new GPIO API.

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

arch/sandbox/dts/sandbox.dts

@@ -19,6 +19,7 @@
 		colour = "cyan";
 		sides = <3>;
 		character = <83>;
+		light-gpios = <&gpio_a 2>, <&gpio_b 6 0>;
 	};
 	square {
 		compatible = "demo-shape";
@@ -126,7 +127,7 @@
 			0x070b0067 0x070c0069>;
 	};
 
-	gpio_a: gpios {
+	gpio_a: gpios@0 {
 		gpio-controller;
 		compatible = "sandbox,gpio";
 		#gpio-cells = <1>;
@@ -134,6 +135,14 @@
 		num-gpios = <20>;
 	};
 
+	gpio_b: gpios@1 {
+		gpio-controller;
+		compatible = "sandbox,gpio";
+		#gpio-cells = <2>;
+		gpio-bank-name = "b";
+		num-gpios = <10>;
+	};
+
 	i2c@0 {
 		#address-cells = <1>;
 		#size-cells = <0>;

common/cmd_demo.c

@@ -39,6 +39,26 @@ static int do_demo_status(cmd_tbl_t *cmdtp, int flag, int argc,
 	return 0;
 }
 
+static int do_demo_light(cmd_tbl_t *cmdtp, int flag, int argc,
+			 char * const argv[])
+{
+	int light;
+	int ret;
+
+	if (argc) {
+		light = simple_strtoul(argv[0], NULL, 16);
+		ret = demo_set_light(demo_dev, light);
+	} else {
+		ret = demo_get_light(demo_dev);
+		if (ret >= 0) {
+			printf("Light: %x\n", ret);
+			ret = 0;
+		}
+	}
+
+	return ret;
+}
+
 int do_demo_list(cmd_tbl_t *cmdtp, int flag, int argc, char * const argv[])
 {
 	struct udevice *dev;
@@ -61,6 +81,7 @@ int do_demo_list(cmd_tbl_t *cmdtp, int flag, int argc, char * const argv[])
 static cmd_tbl_t demo_commands[] = {
 	U_BOOT_CMD_MKENT(list, 0, 1, do_demo_list, "", ""),
 	U_BOOT_CMD_MKENT(hello, 2, 1, do_demo_hello, "", ""),
+	U_BOOT_CMD_MKENT(light, 2, 1, do_demo_light, "", ""),
 	U_BOOT_CMD_MKENT(status, 1, 1, do_demo_status, "", ""),
 };
 
@@ -86,6 +107,10 @@ static int do_demo(cmd_tbl_t *cmdtp, int flag, int argc, char * const argv[])
 			return cmd_process_error(cmdtp, ret);
 		argc--;
 		argv++;
+	} else {
+		demo_dev = NULL;
+		if (demo_cmd->cmd != do_demo_list)
+			return CMD_RET_USAGE;
 	}
 
 	ret = demo_cmd->cmd(demo_cmd, flag, argc, argv);
@@ -98,5 +123,7 @@ U_BOOT_CMD(
 	"Driver model (dm) demo operations",
 	"list                     List available demo devices\n"
 	"demo hello <num> [<char>]     Say hello\n"
-	"demo status <num>             Get demo device status"
+	"demo light [<num>]            Set or get the lights\n"
+	"demo status <num>             Get demo device status\n"
+	"demo list                     List available demo devices"
 );

drivers/demo/demo-shape.c

@@ -11,6 +11,7 @@
 #include <malloc.h>
 #include <dm-demo.h>
 #include <asm/io.h>
+#include <asm/gpio.h>
 
 DECLARE_GLOBAL_DATA_PTR;
 
@@ -20,6 +21,8 @@ DECLARE_GLOBAL_DATA_PTR;
 
 struct shape_data {
 	int num_chars;	/* Number of non-space characters output so far */
+	struct gpio_desc gpio_desc[8];
+	int gpio_count;
 };
 
 /* Crazy little function to draw shapes on the console */
@@ -89,9 +92,52 @@ static int shape_status(struct udevice *dev, int *status)
 	return 0;
 }
 
+static int set_light(struct udevice *dev, int light)
+{
+	struct shape_data *priv = dev_get_priv(dev);
+	struct gpio_desc *desc;
+	int ret;
+	int i;
+
+	desc = priv->gpio_desc;
+	for (i = 0; i < priv->gpio_count; i++, desc++) {
+		uint mask = 1 << i;
+
+		ret = dm_gpio_set_value(desc, light & mask);
+		if (ret < 0)
+			return ret;
+	}
+
+	return 0;
+}
+
+static int get_light(struct udevice *dev)
+{
+	struct shape_data *priv = dev_get_priv(dev);
+	struct gpio_desc *desc;
+	uint value = 0;
+	int ret;
+	int i;
+
+	desc = priv->gpio_desc;
+	for (i = 0; i < priv->gpio_count; i++, desc++) {
+		uint mask = 1 << i;
+
+		ret = dm_gpio_get_value(desc);
+		if (ret < 0)
+			return ret;
+		if (ret)
+			value |= mask;
+	}
+
+	return value;
+}
+
 static const struct demo_ops shape_ops = {
 	.hello = shape_hello,
 	.status = shape_status,
+	.get_light = get_light,
+	.set_light = set_light,
 };
 
 static int shape_ofdata_to_platdata(struct udevice *dev)
@@ -111,6 +157,29 @@ static int shape_ofdata_to_platdata(struct udevice *dev)
 	return 0;
 }
 
+static int dm_shape_probe(struct udevice *dev)
+{
+	struct shape_data *priv = dev_get_priv(dev);
+	int ret;
+
+	ret = gpio_request_list_by_name(dev, "light-gpios", priv->gpio_desc,
+					ARRAY_SIZE(priv->gpio_desc),
+					GPIOD_IS_OUT | GPIOD_IS_OUT_ACTIVE);
+	if (ret < 0)
+		return ret;
+	priv->gpio_count = ret;
+	debug("%s: %d GPIOs\n", __func__, priv->gpio_count);
+
+	return 0;
+}
+
+static int dm_shape_remove(struct udevice *dev)
+{
+	struct shape_data *priv = dev_get_priv(dev);
+
+	return gpio_free_list(dev, priv->gpio_desc, priv->gpio_count);
+}
+
 static const struct udevice_id demo_shape_id[] = {
 	{ "demo-shape", 0 },
 	{ },
@@ -122,6 +191,8 @@ U_BOOT_DRIVER(demo_shape_drv) = {
 	.id	= UCLASS_DEMO,
 	.ofdata_to_platdata = shape_ofdata_to_platdata,
 	.ops	= &shape_ops,
+	.probe = dm_shape_probe,
+	.remove = dm_shape_remove,
 	.priv_auto_alloc_size = sizeof(struct shape_data),
 	.platdata_auto_alloc_size = sizeof(struct dm_demo_pdata),
 };

drivers/demo/demo-uclass.c

@@ -43,6 +43,26 @@ int demo_status(struct udevice *dev, int *status)
 	return ops->status(dev, status);
 }
 
+int demo_get_light(struct udevice *dev)
+{
+	const struct demo_ops *ops = device_get_ops(dev);
+
+	if (!ops->get_light)
+		return -ENOSYS;
+
+	return ops->get_light(dev);
+}
+
+int demo_set_light(struct udevice *dev, int light)
+{
+	const struct demo_ops *ops = device_get_ops(dev);
+
+	if (!ops->set_light)
+		return -ENOSYS;
+
+	return ops->set_light(dev, light);
+}
+
 int demo_parse_dt(struct udevice *dev)
 {
 	struct dm_demo_pdata *pdata = dev_get_platdata(dev);

include/dm-demo.h

@@ -25,10 +25,14 @@ struct dm_demo_pdata {
 struct demo_ops {
 	int (*hello)(struct udevice *dev, int ch);
 	int (*status)(struct udevice *dev, int *status);
+	int (*set_light)(struct udevice *dev, int light);
+	int (*get_light)(struct udevice *dev);
 };
 
 int demo_hello(struct udevice *dev, int ch);
 int demo_status(struct udevice *dev, int *status);
+int demo_set_light(struct udevice *dev, int light);
+int demo_get_light(struct udevice *dev);
 int demo_list(void);
 
 int demo_parse_dt(struct udevice *dev);