linux-kernel - [PATCH v3 1/2] leds: is31fl32xx: Add shutdown pin and generate a 5ms low pulse when startup

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Message-Id: <20200825080758.5283-1-von81@163.com>
Date:   Tue, 25 Aug 2020 16:07:57 +0800
From:   Grant Feng <von81@....com>
To:     von81@....com, jacek.anaszewski@...il.com, pavel@....cz,
        dmurphy@...com, robh+dt@...nel.org, linux-leds@...r.kernel.org,
        devicetree@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: [PATCH v3 1/2] leds: is31fl32xx: Add shutdown pin and generate a 5ms low pulse when startup

generate a 5ms low pulse on shutdown pin when startup, then the chip
becomes more stable in the complex EM environment.

Signed-off-by: Grant Feng <von81@....com>
---
 drivers/leds/leds-is31fl32xx.c | 24 +++++++++++++++++++++---
 1 file changed, 21 insertions(+), 3 deletions(-)

diff --git a/drivers/leds/leds-is31fl32xx.c b/drivers/leds/leds-is31fl32xx.c
index cd768f991da1..946ad2f71e00 100644
--- a/drivers/leds/leds-is31fl32xx.c
+++ b/drivers/leds/leds-is31fl32xx.c
@@ -16,6 +16,8 @@
 #include <linux/module.h>
 #include <linux/of.h>
 #include <linux/of_device.h>
+#include <linux/delay.h>
+#include <linux/gpio/consumer.h>
 
 /* Used to indicate a device has no such register */
 #define IS31FL32XX_REG_NONE 0xFF
@@ -43,6 +45,7 @@ struct is31fl32xx_led_data {
 struct is31fl32xx_priv {
 	const struct is31fl32xx_chipdef *cdef;
 	struct i2c_client *client;
+	struct gpio_desc *shutdown_gpio;
 	unsigned int num_leds;
 	struct is31fl32xx_led_data leds[];
 };
@@ -282,11 +285,17 @@ static int is31fl32xx_software_shutdown(struct is31fl32xx_priv *priv,
 	return 0;
 }
 
-static int is31fl32xx_init_regs(struct is31fl32xx_priv *priv)
+static int is31fl32xx_init(struct is31fl32xx_priv *priv)
 {
 	const struct is31fl32xx_chipdef *cdef = priv->cdef;
 	int ret;
 
+	if (priv->shutdown_gpio) {
+		gpiod_direction_output(priv->shutdown_gpio, 0);
+		mdelay(5);
+		gpiod_direction_output(priv->shutdown_gpio, 1);
+	}
+
 	ret = is31fl32xx_reset_regs(priv);
 	if (ret)
 		return ret;
@@ -372,6 +381,15 @@ static int is31fl32xx_parse_dt(struct device *dev,
 	struct device_node *child;
 	int ret = 0;
 
+	priv->shutdown_gpio = devm_gpiod_get_optional(dev,
+						"shutdown",
+						GPIOD_OUT_HIGH);
+	if (IS_ERR(priv->shutdown_gpio)) {
+		ret = PTR_ERR(priv->shutdown_gpio);
+		dev_err(dev, "Failed to get shutdown gpio: %d\n", ret);
+		return ret;
+	}
+
 	for_each_child_of_node(dev->of_node, child) {
 		struct is31fl32xx_led_data *led_data =
 			&priv->leds[priv->num_leds];
@@ -453,11 +471,11 @@ static int is31fl32xx_probe(struct i2c_client *client,
 	priv->cdef = cdef;
 	i2c_set_clientdata(client, priv);
 
-	ret = is31fl32xx_init_regs(priv);
+	ret = is31fl32xx_parse_dt(dev, priv);
 	if (ret)
 		return ret;
 
-	ret = is31fl32xx_parse_dt(dev, priv);
+	ret = is31fl32xx_init(priv);
 	if (ret)
 		return ret;
 
-- 
2.17.1