[PATCH] usb: ci_hdrc_imx: add optional hub clock

[Maciej S. Szmigiero]

This patch adds ability to define optional clock of connected
USB hub to ChipIdea i.MX usb controller driver.

This is needed for example for UDOO board.
Previously, this board DT file used a fact that non-core registers
of this USB controller have a separate driver (usbmisc_imx) which
did allow defining a separate clock.

Because the non-core registers are in fact using the same clock as
main controller this allowed to use one of such clock definitions
to enable USB hub clock instead.

However, since commit 73dea4a912b2
("usb: chipidea: usbmisc_imx: delete clock information") this
possibility no longer exists and loading USB support on this board
results in a hard SoC lockup.

Note that this is not specific to particular USB hub chip used,
rather than to a particular board.
Since this is a DT-based board there is no board platform file to
put such clock enable.
Also, USB bus devices aren't instantiated in DT file since it is an
enumerable bus.

NOP PHY also can't be used as clock consumer since this
USB controller needs a true MXS phy definition, which accepts only
one clock (different from USB controller one).

Based on a patch previously submitted by Fabio Estevam, with consent.

Signed-off-by: Maciej Szmigiero <mail@xxxxxxxxxxxxxxxxxxxxx>

diff --git a/Documentation/devicetree/bindings/usb/ci-hdrc-imx.txt b/Documentation/devicetree/bindings/usb/ci-hdrc-imx.txt
index 38a5480..fc65f1c 100644
--- a/Documentation/devicetree/bindings/usb/ci-hdrc-imx.txt
+++ b/Documentation/devicetree/bindings/usb/ci-hdrc-imx.txt
@@ -5,6 +5,8 @@ Required properties:
 - reg: Should contain registers location and length
 - interrupts: Should contain controller interrupt
 - fsl,usbphy: phandle of usb phy that connects to the port
+- clocks: phandles of clocks that drive the controller and optionally
+  an USB hub connected to it
 
 Recommended properies:
 - phy_type: the type of the phy connected to the core. Should be one
@@ -20,12 +22,14 @@ Optional properties:
 - external-vbus-divider: enables off-chip resistor divider for Vbus
 - maximum-speed: limit the maximum connection speed to "full-speed".
 - tpl-support: TPL (Targeted Peripheral List) feature for targeted hosts
+- clock-names: must be "default", "hub" if optional USB hub clock is used
 
 Examples:
 usb@02184000 { /* USB OTG */
 	compatible = "fsl,imx6q-usb", "fsl,imx27-usb";
 	reg = <0x02184000 0x200>;
 	interrupts = <0 43 0x04>;
+	clocks = <&clks IMX6QDL_CLK_USBOH3>;
 	fsl,usbphy = <&usbphy1>;
 	fsl,usbmisc = <&usbmisc 0>;
 	disable-over-current;
diff --git a/drivers/usb/chipidea/ci_hdrc_imx.c b/drivers/usb/chipidea/ci_hdrc_imx.c
index 389f0e0..bb7f859 100644
--- a/drivers/usb/chipidea/ci_hdrc_imx.c
+++ b/drivers/usb/chipidea/ci_hdrc_imx.c
@@ -65,6 +65,7 @@ struct ci_hdrc_imx_data {
 	struct usb_phy *phy;
 	struct platform_device *ci_pdev;
 	struct clk *clk;
+	struct clk *clk_hub;
 	struct imx_usbmisc_data *usbmisc_data;
 	bool supports_runtime_pm;
 	bool in_lpm;
@@ -196,6 +197,16 @@ static int ci_hdrc_imx_probe(struct platform_device *pdev)
 		goto disable_device;
 	}
 
+	data->clk_hub = devm_clk_get(&pdev->dev, "hub");
+	if (!IS_ERR(data->clk_hub)) {
+		ret = clk_prepare_enable(data->clk_hub);
+		if (ret) {
+			dev_err(&pdev->dev,
+				"Failed to enable clk_hub: %d\n", ret);
+			goto disable_device;
+		}
+	}
+
 	platform_set_drvdata(pdev, data);
 
 	if (data->supports_runtime_pm) {
@@ -223,6 +234,8 @@ static int ci_hdrc_imx_remove(struct platform_device *pdev)
 		pm_runtime_disable(&pdev->dev);
 		pm_runtime_put_noidle(&pdev->dev);
 	}
+	if (!IS_ERR(data->clk_hub))
+		clk_disable_unprepare(data->clk_hub);
 	ci_hdrc_remove_device(data->ci_pdev);
 	clk_disable_unprepare(data->clk);
 

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