usb: uhci: Add clk support to uhci-platform

The Aspeed SoCs use uhci-platform. With the new dynamic clock
control framework, the corresponding IP block clock must be
properly enabled.

This is a simplified variant of what ehci-platform does, it
looks for *one* clock attached to the device, and if it's
there, enables it.

Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Acked-by: Alan Stern <stern@rowland.harvard.edu>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/usb/host/uhci-hcd.h

@@ -4,6 +4,7 @@
 
 #include <linux/list.h>
 #include <linux/usb.h>
+#include <linux/clk.h>
 
 #define usb_packetid(pipe)	(usb_pipein(pipe) ? USB_PID_IN : USB_PID_OUT)
 #define PIPE_DEVEP_MASK		0x0007ff00
@@ -447,6 +448,8 @@ struct uhci_hcd {
 	int total_load;				/* Sum of array values */
 	short load[MAX_PHASE];			/* Periodic allocations */
 
+	struct clk *clk;			/* (optional) clock source */
+
 	/* Reset host controller */
 	void	(*reset_hc) (struct uhci_hcd *uhci);
 	int	(*check_and_reset_hc) (struct uhci_hcd *uhci);

drivers/usb/host/uhci-platform.c

@@ -89,6 +89,8 @@ static int uhci_hcd_platform_probe(struct platform_device *pdev)
 	if (!hcd)
 		return -ENOMEM;
 
+	uhci = hcd_to_uhci(hcd);
+
 	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
 	hcd->regs = devm_ioremap_resource(&pdev->dev, res);
 	if (IS_ERR(hcd->regs)) {
@@ -98,8 +100,6 @@ static int uhci_hcd_platform_probe(struct platform_device *pdev)
 	hcd->rsrc_start = res->start;
 	hcd->rsrc_len = resource_size(res);
 
-	uhci = hcd_to_uhci(hcd);
-
 	uhci->regs = hcd->regs;
 
 	/* Grab some things from the device-tree */
@@ -119,13 +119,28 @@ static int uhci_hcd_platform_probe(struct platform_device *pdev)
 				 "Enabled Aspeed implementation workarounds\n");
 		}
 	}
+
+	/* Get and enable clock if any specified */
+	uhci->clk = devm_clk_get(&pdev->dev, NULL);
+	if (IS_ERR(uhci->clk)) {
+		ret = PTR_ERR(uhci->clk);
+		goto err_rmr;
+	}
+	ret = clk_prepare_enable(uhci->clk);
+	if (ret) {
+		dev_err(&pdev->dev, "Error couldn't enable clock (%d)\n", ret);
+		goto err_rmr;
+	}
+
 	ret = usb_add_hcd(hcd, pdev->resource[1].start, IRQF_SHARED);
 	if (ret)
-		goto err_rmr;
+		goto err_clk;
 
 	device_wakeup_enable(hcd->self.controller);
 	return 0;
 
+err_clk:
+	clk_disable_unprepare(uhci->clk);
 err_rmr:
 	usb_put_hcd(hcd);
 
@@ -135,7 +150,9 @@ static int uhci_hcd_platform_probe(struct platform_device *pdev)
 static int uhci_hcd_platform_remove(struct platform_device *pdev)
 {
 	struct usb_hcd *hcd = platform_get_drvdata(pdev);
+	struct uhci_hcd *uhci = hcd_to_uhci(hcd);
 
+	clk_disable_unprepare(uhci->clk);
 	usb_remove_hcd(hcd);
 	usb_put_hcd(hcd);