[PATCHv2 1/2] usb: bcma: add regulator support

[Rosen Penev <rosenp@gmail.com>]

bcma-hcd drives the USB power line by grabbing the undocumented
"vcc-gpio" from the controller node and poking it through gpiolib.
Besides relying on a non-standard binding, this cannot work on boards
such as the NETGEAR R7000 and R8000 where one chipcommon GPIO powers
both the USB2 and USB3 cores: the two controllers each request that
GPIO exclusively, so the second one fails with -EBUSY and its port
stays dead.

Add support for the standard regulator interface. Each core obtains its
(shared) VBUS supply through devm_regulator_get() and the regulator core
reference-counts the enable/disable requests, allowing both controllers to
drive one GPIO without conflicts.

Assisted-by: LLM
Signed-off-by: Rosen Penev <rosenp@gmail.com>
---
 drivers/usb/host/bcma-hcd.c | 54 +++++++++++++++++++++++++++++--------
 1 file changed, 43 insertions(+), 11 deletions(-)

diff --git a/drivers/usb/host/bcma-hcd.c b/drivers/usb/host/bcma-hcd.c
index 519386255886..0d5a220b6988 100644
--- a/drivers/usb/host/bcma-hcd.c
+++ b/drivers/usb/host/bcma-hcd.c
@@ -26,6 +26,7 @@
 #include <linux/slab.h>
 #include <linux/of.h>
 #include <linux/of_platform.h>
+#include <linux/regulator/consumer.h>
 #include <linux/usb/ehci_pdriver.h>
 #include <linux/usb/ohci_pdriver.h>
 
@@ -41,6 +42,7 @@ struct bcma_hcd_device {
 	struct platform_device *ehci_dev;
 	struct platform_device *ohci_dev;
 	struct gpio_desc *gpio_desc;
+	struct regulator *regulator;
 };
 
 /* Wait for bitmask in a register to get set or cleared.
@@ -280,14 +282,23 @@ static int bcma_hcd_usb20_ns_init(struct bcma_hcd_device *bcma_hcd)
 	return 0;
 }
 
-static void bcma_hci_platform_power_gpio(struct bcma_device *dev, bool val)
+static int bcma_hci_platform_power(struct bcma_device *dev, bool on)
 {
 	struct bcma_hcd_device *usb_dev = bcma_get_drvdata(dev);
+	int err;
+
+	if (usb_dev->gpio_desc)
+		return gpiod_set_value(usb_dev->gpio_desc, on);
 
-	if (!usb_dev->gpio_desc)
-		return;
+	if (!usb_dev->regulator)
+		return 0;
 
-	gpiod_set_value(usb_dev->gpio_desc, val);
+	if (on)
+		err = regulator_enable(usb_dev->regulator);
+	else
+		err = regulator_disable(usb_dev->regulator);
+
+	return err;
 }
 
 static const struct usb_ehci_pdata ehci_pdata = {
@@ -395,12 +406,12 @@ static int bcma_hcd_usb30_init(struct bcma_hcd_device *bcma_hcd)
 static int bcma_hcd_probe(struct bcma_device *core)
 {
 	int err;
+	struct device *dev = &core->dev;
 	struct bcma_hcd_device *usb_dev;
 
 	/* TODO: Probably need checks here; is the core connected? */
 
-	usb_dev = devm_kzalloc(&core->dev, sizeof(struct bcma_hcd_device),
-			       GFP_KERNEL);
+	usb_dev = devm_kzalloc(dev, sizeof(*usb_dev), GFP_KERNEL);
 	if (!usb_dev)
 		return -ENOMEM;
 	usb_dev->core = core;
@@ -411,6 +422,14 @@ static int bcma_hcd_probe(struct bcma_device *core)
 		return dev_err_probe(&core->dev, PTR_ERR(usb_dev->gpio_desc),
 				     "error obtaining VCC GPIO");
 
+	usb_dev->regulator = devm_regulator_get(dev, "vbus");
+	if (IS_ERR(usb_dev->regulator))
+		return dev_err_probe(dev, PTR_ERR(usb_dev->regulator), "error obtaining VBUS regulator");
+
+	err = regulator_enable(usb_dev->regulator);
+	if (err)
+		return dev_err_probe(dev, err, "error enabling VCC regulator");
+
 	switch (core->id.id) {
 	case BCMA_CORE_USB20_HOST:
 		if (IS_ENABLED(CONFIG_ARM))
@@ -427,13 +446,16 @@ static int bcma_hcd_probe(struct bcma_device *core)
 		err = bcma_hcd_usb30_init(usb_dev);
 		break;
 	default:
-		return -ENODEV;
+		err = -ENODEV;
 	}
 	if (err)
-		return err;
+		goto error;
 
 	bcma_set_drvdata(core, usb_dev);
 	return 0;
+error:
+	regulator_disable(usb_dev->regulator);
+	return err;
 }
 
 static void bcma_hcd_remove(struct bcma_device *dev)
@@ -442,6 +464,8 @@ static void bcma_hcd_remove(struct bcma_device *dev)
 	struct platform_device *ohci_dev = usb_dev->ohci_dev;
 	struct platform_device *ehci_dev = usb_dev->ehci_dev;
 
+	regulator_disable(usb_dev->regulator);
+
 	if (ohci_dev)
 		platform_device_unregister(ohci_dev);
 	if (ehci_dev)
@@ -452,7 +476,7 @@ static void bcma_hcd_remove(struct bcma_device *dev)
 
 static void bcma_hcd_shutdown(struct bcma_device *dev)
 {
-	bcma_hci_platform_power_gpio(dev, false);
+	bcma_hci_platform_power(dev, false);
 	bcma_core_disable(dev, 0);
 }
 
@@ -460,7 +484,11 @@ static void bcma_hcd_shutdown(struct bcma_device *dev)
 
 static int bcma_hcd_suspend(struct bcma_device *dev)
 {
-	bcma_hci_platform_power_gpio(dev, false);
+	int err;
+
+	err = bcma_hci_platform_power(dev, false);
+	if (err)
+		return err;
 	bcma_core_disable(dev, 0);
 
 	return 0;
@@ -468,7 +496,11 @@ static int bcma_hcd_suspend(struct bcma_device *dev)
 
 static int bcma_hcd_resume(struct bcma_device *dev)
 {
-	bcma_hci_platform_power_gpio(dev, true);
+	int err;
+
+	err = bcma_hci_platform_power(dev, true);
+	if (err)
+		return err;
 	bcma_core_enable(dev, 0);
 
 	return 0;
-- 
2.55.0