linux-kernel - [PATCH 1/2] backlight: lm3630a: add an enable gpio for the HWEN pin

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Date:   Sun,  8 Sep 2019 22:37:03 +0200
From:   Andreas Kemnade <andreas@...nade.info>
To:     lee.jones@...aro.org, daniel.thompson@...aro.org,
        jingoohan1@...il.com, jacek.anaszewski@...il.com, pavel@....cz,
        dmurphy@...com, robh+dt@...nel.org, mark.rutland@....com,
        b.zolnierkie@...sung.com, dri-devel@...ts.freedesktop.org,
        linux-leds@...r.kernel.org, devicetree@...r.kernel.org,
        linux-kernel@...r.kernel.org, linux-fbdev@...r.kernel.org,
        "H. Nikolaus Schaller" <hns@...delico.com>
Cc:     Andreas Kemnade <andreas@...nade.info>
Subject: [PATCH 1/2] backlight: lm3630a: add an enable gpio for the HWEN pin

For now just enable it in the probe function to allow i2c
access and disable it on remove. Disabling also means resetting
the register values to default.

Tested on Kobo Clara HD.

Signed-off-by: Andreas Kemnade <andreas@...nade.info>
---
 drivers/video/backlight/lm3630a_bl.c | 18 ++++++++++++++++++
 1 file changed, 18 insertions(+)

diff --git a/drivers/video/backlight/lm3630a_bl.c b/drivers/video/backlight/lm3630a_bl.c
index b04b35d007a2..3b45a1733198 100644
--- a/drivers/video/backlight/lm3630a_bl.c
+++ b/drivers/video/backlight/lm3630a_bl.c
@@ -12,6 +12,8 @@
 #include <linux/uaccess.h>
 #include <linux/interrupt.h>
 #include <linux/regmap.h>
+#include <linux/gpio/consumer.h>
+#include <linux/gpio.h>
 #include <linux/pwm.h>
 #include <linux/platform_data/lm3630a_bl.h>
 
@@ -48,6 +50,7 @@ struct lm3630a_chip {
 	struct lm3630a_platform_data *pdata;
 	struct backlight_device *bleda;
 	struct backlight_device *bledb;
+	struct gpio_desc *enable_gpio;
 	struct regmap *regmap;
 	struct pwm_device *pwmd;
 };
@@ -506,6 +509,14 @@ static int lm3630a_probe(struct i2c_client *client,
 		return -ENOMEM;
 	pchip->dev = &client->dev;
 
+	pchip->enable_gpio = devm_gpiod_get_optional(&client->dev, "enable",
+						GPIOD_ASIS);
+	if (IS_ERR(pchip->enable_gpio)) {
+		rval = PTR_ERR(pchip->enable_gpio);
+		return rval;
+	}
+
+
 	pchip->regmap = devm_regmap_init_i2c(client, &lm3630a_regmap);
 	if (IS_ERR(pchip->regmap)) {
 		rval = PTR_ERR(pchip->regmap);
@@ -535,6 +546,10 @@ static int lm3630a_probe(struct i2c_client *client,
 	}
 	pchip->pdata = pdata;
 
+	if (pchip->enable_gpio) {
+		gpiod_set_value_cansleep(pchip->enable_gpio, 1);
+		usleep_range(1000, 2000);
+	}
 	/* chip initialize */
 	rval = lm3630a_chip_init(pchip);
 	if (rval < 0) {
@@ -586,6 +601,9 @@ static int lm3630a_remove(struct i2c_client *client)
 	if (rval < 0)
 		dev_err(pchip->dev, "i2c failed to access register\n");
 
+	if (pchip->enable_gpio)
+		gpiod_set_value_cansleep(pchip->enable_gpio, 0);
+
 	if (pchip->irq) {
 		free_irq(pchip->irq, pchip);
 		flush_workqueue(pchip->irqthread);
-- 
2.20.1