dm: gpio: Add gpio_requestf() helper for printf() strings

Add a helper which permits a printf()-style format string for the requester
string.

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

doc/driver-model/README.txt

@@ -95,7 +95,7 @@ are provided in test/dm. To run them, try:
 You should see something like this:
 
     <...U-Boot banner...>
-    Running 26 driver model tests
+    Running 27 driver model tests
     Test: dm_test_autobind
     Test: dm_test_autoprobe
     Test: dm_test_bus_children
@@ -117,6 +117,7 @@ You should see something like this:
     Test: dm_test_gpio
     extra-gpios: get_value: error: gpio b5 not reserved
     Test: dm_test_gpio_anon
+    Test: dm_test_gpio_requestf
     Test: dm_test_leak
     Test: dm_test_lifecycle
     Test: dm_test_operations

drivers/gpio/gpio-uclass.c

@@ -130,6 +130,27 @@ int gpio_request(unsigned gpio, const char *label)
 	return 0;
 }
 
+/**
+ * gpio_requestf() - [COMPAT] Request GPIO
+ * @gpio:	GPIO number
+ * @fmt:	Format string for the requested GPIO
+ * @...:	Arguments for the printf() format string
+ *
+ * This function implements the API that's compatible with current
+ * GPIO API used in U-Boot. The request is forwarded to particular
+ * GPIO driver. Returns 0 on success, negative value on error.
+ */
+int gpio_requestf(unsigned gpio, const char *fmt, ...)
+{
+	va_list args;
+	char buf[40];
+
+	va_start(args, fmt);
+	vscnprintf(buf, sizeof(buf), fmt, args);
+	va_end(args);
+	return gpio_request(gpio, buf);
+}
+
 /**
  * gpio_free() - [COMPAT] Relinquish GPIO
  * gpio:	GPIO number

include/asm-generic/gpio.h

@@ -145,6 +145,16 @@ int gpio_get_function(struct udevice *dev, int offset, const char **namep);
  */
 int gpio_get_raw_function(struct udevice *dev, int offset, const char **namep);
 
+/**
+ * gpio_requestf() - request a GPIO using a format string for the owner
+ *
+ * This is a helper function for gpio_request(). It allows you to provide
+ * a printf()-format string for the GPIO owner. It calls gpio_request() with
+ * the string that is created
+ */
+int gpio_requestf(unsigned gpio, const char *fmt, ...)
+		__attribute__ ((format (__printf__, 2, 3)));
+
 /**
  * struct struct dm_gpio_ops - Driver model GPIO operations
  *

test/dm/gpio.c

@@ -120,3 +120,21 @@ static int dm_test_gpio_anon(struct dm_test_state *dms)
 	return 0;
 }
 DM_TEST(dm_test_gpio_anon, DM_TESTF_SCAN_PDATA | DM_TESTF_SCAN_FDT);
+
+/* Test that gpio_requestf() works as expected */
+static int dm_test_gpio_requestf(struct dm_test_state *dms)
+{
+	unsigned int offset, gpio;
+	struct udevice *dev;
+	char buf[80];
+
+	ut_assertok(gpio_lookup_name("b5", &dev, &offset, &gpio));
+	ut_assertok(gpio_requestf(gpio, "testing %d %s", 1, "hi"));
+	sandbox_gpio_set_direction(dev, offset, 1);
+	sandbox_gpio_set_value(dev, offset, 1);
+	ut_assertok(gpio_get_status(dev, offset, buf, sizeof(buf)));
+	ut_asserteq_str("b5: output: 1 [x] testing 1 hi", buf);
+
+	return 0;
+}
+DM_TEST(dm_test_gpio_requestf, DM_TESTF_SCAN_PDATA | DM_TESTF_SCAN_FDT);