[PATCH] [v3] leds: gpio: make legacy gpiolib interface optional

[Arnd Bergmann <arnd@kernel.org>]

From: Arnd Bergmann <arnd@arndb.de>

There are still a handful of ancient mips/armv5/sh boards that use the
gpio_led:gpio member to pass an old-style gpio number, but all modern
users have been converted to gpio descriptors.

While the CONFIG_GPIOLIB_LEGACY option that guards devm_gpio_request_one()
and related helpers is currently turned on in all kernel builds,
the plan is to only enable it on the few platforms that actually
pass gpio numbers in any platform_data.

Split out the legacy portion of the platform_data handling into a custom
helper function that is guarded with in #ifdef block, to allow the
the leds-gpio driver to compile cleanly when CONFIG_GPIOLIB_LEGACY
gets turned off. Once the last user is converted, this function can
be removed.

Link: https://lore.kernel.org/all/e9252384-a55c-4a91-9c61-06e05a0b2ce4@app.fastmail.com/
Reviewed-by: Linus Walleij <linusw@kernel.org>
Reviewed-by: Bartosz Golaszewski <bartosz.golaszewski@oss.qualcomm.com>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
---
v3: simplify gpio_led_get_gpiod
v2: rework a little bit to keep the legacy code path more separate,
    extend changelog description

Related to this, we may also want to remove support for passing
a gpio descriptor in the ->gpiod flag. The only user doing this
at the moment was introduced in commit 1892e87a3e91 ("powerpc/warp:
switch to using gpiod API").
---
 drivers/leds/leds-gpio.c | 54 ++++++++++++++++++++++++++--------------
 include/linux/leds.h     |  2 ++
 2 files changed, 38 insertions(+), 18 deletions(-)

diff --git a/drivers/leds/leds-gpio.c b/drivers/leds/leds-gpio.c
index 961acc18d0ac..109e2316b775 100644
--- a/drivers/leds/leds-gpio.c
+++ b/drivers/leds/leds-gpio.c
@@ -212,7 +212,6 @@ static struct gpio_desc *gpio_led_get_gpiod(struct device *dev, int idx,
 					    const struct gpio_led *template)
 {
 	struct gpio_desc *gpiod;
-	int ret;
 
 	/*
 	 * This means the LED does not come from the device tree
@@ -221,18 +220,30 @@ static struct gpio_desc *gpio_led_get_gpiod(struct device *dev, int idx,
 	 * the GPIO from there.
 	 */
 	gpiod = devm_gpiod_get_index_optional(dev, NULL, idx, GPIOD_OUT_LOW);
-	if (IS_ERR(gpiod))
-		return gpiod;
-	if (gpiod) {
+	if (!IS_ERR(gpiod))
 		gpiod_set_consumer_name(gpiod, template->name);
-		return gpiod;
-	}
 
-	/*
-	 * This is the legacy code path for platform code that
-	 * still uses GPIO numbers. Ultimately we would like to get
-	 * rid of this block completely.
-	 */
+	return gpiod;
+}
+
+#ifdef CONFIG_GPIOLIB_LEGACY
+/*
+ * This is the legacy code path for platform code that still uses
+ * GPIO numbers, mainly MIPS and SuperH board files.
+ * Ultimately we would like to get rid of this block completely.
+ *
+ * ppc44x-warp sets the template->gpiod directly instead of
+ * adding a lookup table or device properties. This is not
+ * much better.
+ */
+static struct gpio_desc *gpio_led_get_legacy_gpiod(struct device *dev, int idx,
+						   const struct gpio_led *template)
+{
+	struct gpio_desc *gpiod;
+	int ret;
+
+	if (template->gpiod)
+		return template->gpiod;
 
 	/* skip leds that aren't available */
 	if (!gpio_is_valid(template->gpio))
@@ -252,6 +263,13 @@ static struct gpio_desc *gpio_led_get_gpiod(struct device *dev, int idx,
 
 	return gpiod;
 }
+#else
+static struct gpio_desc *gpio_led_get_legacy_gpiod(struct device *dev, int idx,
+						   const struct gpio_led *template)
+{
+	return template->gpiod ?: ERR_PTR(-ENOENT);
+}
+#endif
 
 static int gpio_led_probe(struct platform_device *pdev)
 {
@@ -270,14 +288,14 @@ static int gpio_led_probe(struct platform_device *pdev)
 			const struct gpio_led *template = &pdata->leds[i];
 			struct gpio_led_data *led_dat = &priv->leds[i];
 
-			if (template->gpiod)
-				led_dat->gpiod = template->gpiod;
-			else
-				led_dat->gpiod =
-					gpio_led_get_gpiod(dev, i, template);
+			led_dat->gpiod = gpio_led_get_gpiod(dev, i, template);
+			if (!led_dat->gpiod)
+				led_dat->gpiod = gpio_led_get_legacy_gpiod(dev,
+								  i, template);
+
 			if (IS_ERR(led_dat->gpiod)) {
-				dev_info(dev, "Skipping unavailable LED gpio %d (%s)\n",
-					 template->gpio, template->name);
+				dev_info(dev, "Skipping unavailable LED gpio %s\n",
+					 template->name);
 				continue;
 			}
 
diff --git a/include/linux/leds.h b/include/linux/leds.h
index b16b803cc1ac..e646bffcd8e7 100644
--- a/include/linux/leds.h
+++ b/include/linux/leds.h
@@ -676,8 +676,10 @@ typedef int (*gpio_blink_set_t)(struct gpio_desc *desc, int state,
 struct gpio_led {
 	const char *name;
 	const char *default_trigger;
+#ifdef CONFIG_GPIOLIB_LEGACY
 	unsigned 	gpio;
 	unsigned	active_low : 1;
+#endif
 	unsigned	retain_state_suspended : 1;
 	unsigned	panic_indicator : 1;
 	unsigned	default_state : 2;
-- 
2.39.5