usb: dwc2: Add reset control to dwc2

Allow for platforms that have a reset controller driver in place to bring
the USB IP out of reset.

Signed-off-by: Dinh Nguyen <dinguyen@opensource.altera.com>
Acked-by: John Youn <johnyoun@synopsys.com>
Tested-by: Stefan Wahren <stefan.wahren@i2se.com>
Signed-off-by: Felipe Balbi <felipe.balbi@linux.intel.com>

2 files changed, 23 insertions, 0 deletions

diff --git a/drivers/usb/dwc2/core.h b/drivers/usb/dwc2/core.h
index 9fae0291cd69..d64551243789 100644
--- a/drivers/usb/dwc2/core.h
+++ b/drivers/usb/dwc2/core.h
@@ -868,6 +868,7 @@ struct dwc2_hsotg {
         void *priv;
         int     irq;
         struct clk *clk;
+        struct reset_control *reset;
 
         unsigned int queuing_high_bandwidth:1;
         unsigned int srp_success:1;
diff --git a/drivers/usb/dwc2/platform.c b/drivers/usb/dwc2/platform.c
index fc6f5251de5d..530959a8a6d1 100644
--- a/drivers/usb/dwc2/platform.c
+++ b/drivers/usb/dwc2/platform.c
@@ -45,6 +45,7 @@
 #include <linux/platform_device.h>
 #include <linux/phy/phy.h>
 #include <linux/platform_data/s3c-hsotg.h>
+#include <linux/reset.h>
 
 #include <linux/usb/of.h>
 
@@ -337,6 +338,24 @@ static int dwc2_lowlevel_hw_init(struct dwc2_hsotg *hsotg)
 {
         int i, ret;
 
+        hsotg->reset = devm_reset_control_get_optional(hsotg->dev, "dwc2");
+        if (IS_ERR(hsotg->reset)) {
+                ret = PTR_ERR(hsotg->reset);
+                switch (ret) {
+                case -ENOENT:
+                case -ENOTSUPP:
+                        hsotg->reset = NULL;
+                        break;
+                default:
+                        dev_err(hsotg->dev, "error getting reset control %d\n",
+                                ret);
+                        return ret;
+                }
+        }
+
+        if (hsotg->reset)
+                reset_control_deassert(hsotg->reset);
+
         /* Set default UTMI width */
         hsotg->phyif = GUSBCFG_PHYIF16;
 
@@ -434,6 +453,9 @@ static int dwc2_driver_remove(struct platform_device *dev)
         if (hsotg->ll_hw_enabled)
                 dwc2_lowlevel_hw_disable(hsotg);
 
+        if (hsotg->reset)
+                reset_control_assert(hsotg->reset);
+
         return 0;
 }