[PATCH v3 2/2] regulator: rpi-panel-v2: Add vcc-supply support

[Shashank Maurya]

The Raspberry Pi 7" touchscreen panel V2 MCU is powered from an external
power rail which has to be enabled before any I2C register access is
attempted. Use devm_regulator_get() to obtain the vcc supply and enable
it at the start of probe.

devm_regulator_get() returns a dummy regulator when the supply is not
described in the device tree, so device trees without a vcc-supply
property keep working as before.

Signed-off-by: Shashank Maurya <shashank.maurya at oss.qualcomm.com>
---
 drivers/regulator/rpi-panel-v2-regulator.c | 12 ++++++++++++
 1 file changed, 12 insertions(+)

diff --git a/drivers/regulator/rpi-panel-v2-regulator.c b/drivers/regulator/rpi-panel-v2-regulator.c
index 30b78aa75ee3..e54d675962e7 100644
--- a/drivers/regulator/rpi-panel-v2-regulator.c
+++ b/drivers/regulator/rpi-panel-v2-regulator.c
@@ -11,6 +11,7 @@
 #include <linux/module.h>
 #include <linux/pwm.h>
 #include <linux/regmap.h>
+#include <linux/regulator/consumer.h>
 
 /* I2C registers of the microcontroller. */
 #define REG_ID		0x01
@@ -66,10 +67,21 @@ static int rpi_panel_v2_i2c_probe(struct i2c_client *i2c)
 		.parent		= &i2c->dev,
 		.reg_set_base	= REG_POWERON,
 	};
+	struct regulator *vcc;
 	struct regmap *regmap;
 	struct pwm_chip *pc;
 	int ret;
 
+	vcc = devm_regulator_get(&i2c->dev, "vcc");
+	if (IS_ERR(vcc))
+		return dev_err_probe(&i2c->dev, PTR_ERR(vcc),
+				     "Failed to get vcc supply\n");
+
+	ret = regulator_enable(vcc);
+	if (ret)
+		return dev_err_probe(&i2c->dev, ret,
+				     "Failed to enable vcc supply\n");
+
 	pc = devm_pwmchip_alloc(&i2c->dev, 1, 0);
 	if (IS_ERR(pc))
 		return PTR_ERR(pc);

-- 
2.34.1