[PATCH 4/7] usb: ehci-platform: add optional reset controller retrieval

[Maxime Ripard]

From: Boris BREZILLON <boris.brezillon at free-electrons.com>

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 at free-electrons.com>
Signed-off-by: Maxime Ripard <maxime.ripard at free-electrons.com>
---
 Documentation/devicetree/bindings/usb/usb-ehci.txt |  1 +
 drivers/usb/host/ehci-platform.c                   | 25 +++++++++++++++++++++-
 2 files changed, 25 insertions(+), 1 deletion(-)

diff --git a/Documentation/devicetree/bindings/usb/usb-ehci.txt b/Documentation/devicetree/bindings/usb/usb-ehci.txt
index ff151ec084c4..43c1a4e06767 100644
--- a/Documentation/devicetree/bindings/usb/usb-ehci.txt
+++ b/Documentation/devicetree/bindings/usb/usb-ehci.txt
@@ -15,6 +15,7 @@ Optional properties:
  - clocks : a list of phandle + clock specifier pairs
  - phys : phandle + phy specifier pair
  - phy-names : "usb"
+ - resets : phandle + reset specifier pair
 
 Example (Sequoia 440EPx):
     ehci at e0000300 {
diff --git a/drivers/usb/host/ehci-platform.c b/drivers/usb/host/ehci-platform.c
index c7dd93aad20c..4ee67728e443 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;
 };
 
@@ -84,10 +86,16 @@ static int ehci_platform_power_on(struct platform_device *dev)
 			goto err_disable_clks;
 	}
 
+	if (priv->rst) {
+		ret = reset_control_deassert(priv->rst);
+		if (ret)
+			goto err_disable_clks;
+	}
+
 	if (priv->phy) {
 		ret = phy_init(priv->phy);
 		if (ret)
-			goto err_disable_clks;
+			goto err_assert_rst;
 
 		ret = phy_power_on(priv->phy);
 		if (ret)
@@ -98,6 +106,9 @@ static int ehci_platform_power_on(struct platform_device *dev)
 
 err_exit_phy:
 	phy_exit(priv->phy);
+err_assert_rst:
+	if (priv->rst)
+		reset_control_assert(priv->rst);
 err_disable_clks:
 	while (--clk >= 0)
 		clk_disable_unprepare(priv->clks[clk]);
@@ -119,6 +130,9 @@ static void ehci_platform_power_off(struct platform_device *dev)
 	for (clk = EHCI_MAX_CLKS - 1; clk >= 0; clk--)
 		if (priv->clks[clk])
 			clk_disable_unprepare(priv->clks[clk]);
+
+	if (priv->rst)
+		reset_control_assert(priv->rst);
 }
 
 static struct hc_driver __read_mostly ehci_platform_hc_driver;
@@ -206,6 +220,15 @@ static int ehci_platform_probe(struct platform_device *dev)
 				break;
 			}
 		}
+
+		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;
+		}
 	}
 
 	if (pdata->big_endian_desc)
-- 
1.9.1