usb: ehci-platform: add optional reset controller retrieval

On the Allwinner's A31 SoC the reset line connected to the EHCI IP has to
be deasserted for the EHCI block to be usable.

Add support for an optional reset controller that will be deasserted on
power off and asserted on power on.

Signed-off-by: Boris BREZILLON <boris.brezillon@free-electrons.com>
Signed-off-by: Maxime Ripard <maxime.ripard@free-electrons.com>
Reviewed-by: Hans de Goede <hdegoede@redhat.com>
Acked-by: Alan Stern <stern@rowland.harvard.edu>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

1 files changed, 23 insertions, 3 deletions

diff --git a/drivers/usb/host/ehci-platform.c b/drivers/usb/host/ehci-platform.c
index c7dd93aad20c..2f5b9ce3e042 100644
--- a/drivers/usb/host/ehci-platform.c
+++ b/drivers/usb/host/ehci-platform.c
@@ -29,6 +29,7 @@
 #include <linux/of.h>
 #include <linux/phy/phy.h>
 #include <linux/platform_device.h>
+#include <linux/reset.h>
 #include <linux/usb.h>
 #include <linux/usb/hcd.h>
 #include <linux/usb/ehci_pdriver.h>
@@ -41,6 +42,7 @@
 
 struct ehci_platform_priv {
         struct clk *clks[EHCI_MAX_CLKS];
+        struct reset_control *rst;
         struct phy *phy;
 };
 
@@ -208,6 +210,18 @@ static int ehci_platform_probe(struct platform_device *dev)
                 }
         }
 
+        priv->rst = devm_reset_control_get_optional(&dev->dev, NULL);
+        if (IS_ERR(priv->rst)) {
+                err = PTR_ERR(priv->rst);
+                if (err == -EPROBE_DEFER)
+                        goto err_put_clks;
+                priv->rst = NULL;
+        } else {
+                err = reset_control_deassert(priv->rst);
+                if (err)
+                        goto err_put_clks;
+        }
+
         if (pdata->big_endian_desc)
                 ehci->big_endian_desc = 1;
         if (pdata->big_endian_mmio)
@@ -218,7 +232,7 @@ static int ehci_platform_probe(struct platform_device *dev)
                 dev_err(&dev->dev,
                         "Error: CONFIG_USB_EHCI_BIG_ENDIAN_MMIO not set\n");
                 err = -EINVAL;
-                goto err_put_clks;
+                goto err_reset;
         }
 #endif
 #ifndef CONFIG_USB_EHCI_BIG_ENDIAN_DESC
@@ -226,14 +240,14 @@ static int ehci_platform_probe(struct platform_device *dev)
                 dev_err(&dev->dev,
                         "Error: CONFIG_USB_EHCI_BIG_ENDIAN_DESC not set\n");
                 err = -EINVAL;
-                goto err_put_clks;
+                goto err_reset;
         }
 #endif
 
         if (pdata->power_on) {
                 err = pdata->power_on(dev);
                 if (err < 0)
-                        goto err_put_clks;
+                        goto err_reset;
         }
 
         hcd->rsrc_start = res_mem->start;
@@ -256,6 +270,9 @@ static int ehci_platform_probe(struct platform_device *dev)
 err_power:
         if (pdata->power_off)
                 pdata->power_off(dev);
+err_reset:
+        if (priv->rst)
+                reset_control_assert(priv->rst);
 err_put_clks:
         while (--clk >= 0)
                 clk_put(priv->clks[clk]);
@@ -280,6 +297,9 @@ static int ehci_platform_remove(struct platform_device *dev)
         if (pdata->power_off)
                 pdata->power_off(dev);
 
+        if (priv->rst)
+                reset_control_assert(priv->rst);
+
         for (clk = 0; clk < EHCI_MAX_CLKS && priv->clks[clk]; clk++)
                 clk_put(priv->clks[clk]);