[PATCH] usb: fsl-mph-dr-of: add regulator support

[Rosen Penev <rosenp@gmail.com>]

Some devices have a GPIO that controls power to the USB bus. Add
support for a vbus regulator to have the kernel control it automatically
instead of having to rely on userspace.

Acquire the regulator in the common probe path so that it works for
all fsl-usb2-dr compatible controllers, not just MPC5121.

Tested on a TP-LINK WDR4900v1 by adding roughly the following

reg_power_usb: regulator {
	compatible = "regulator-fixed";
	regulator-name = "power_usb";
	regulator-min-microvolt = <5000000>;
	regulator-max-microvolt = <5000000>;
	gpios = <&gpio0 10 GPIO_ACTIVE_HIGH>;  
	enable-active-high;
	regulator-boot-on;
};

uhubctl and rmmod both turn USB power off.

Assisted-by: opencode:big-pickle
Signed-off-by: Rosen Penev <rosenp@gmail.com>
---
 drivers/usb/host/fsl-mph-dr-of.c | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/drivers/usb/host/fsl-mph-dr-of.c b/drivers/usb/host/fsl-mph-dr-of.c
index 852649156b16..85b08f2f162d 100644
--- a/drivers/usb/host/fsl-mph-dr-of.c
+++ b/drivers/usb/host/fsl-mph-dr-of.c
@@ -14,6 +14,7 @@
 #include <linux/clk.h>
 #include <linux/module.h>
 #include <linux/dma-mapping.h>
+#include <linux/regulator/consumer.h>
 
 struct fsl_usb2_dev_data {
 	char *dr_mode;		/* controller mode */
@@ -182,7 +183,7 @@ static int fsl_usb2_mph_dr_of_probe(struct platform_device *ofdev)
 	const struct fsl_usb2_platform_data *match_data;
 	const unsigned char *prop;
 	static unsigned int idx;
-	int i;
+	int i, err;
 
 	if (!of_device_is_available(np))
 		return -ENODEV;
@@ -242,6 +243,10 @@ static int fsl_usb2_mph_dr_of_probe(struct platform_device *ofdev)
 		}
 	}
 
+	err = devm_regulator_get_enable_optional(&ofdev->dev, "vbus");
+	if (err)
+		return dev_err_probe(&ofdev->dev, err, "failed to get vbus regulator\n");
+
 	for (i = 0; i < ARRAY_SIZE(dev_data->drivers); i++) {
 		if (!dev_data->drivers[i])
 			continue;
-- 
2.55.0