usb: uhci: Add clk support to uhci-platform

[Benjamin Herrenschmidt <benh@kernel.crashing.org>]

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>
---
 drivers/usb/host/uhci-hcd.h      |  3 +++
 drivers/usb/host/uhci-platform.c | 15 +++++++++++++++
 2 files changed, 18 insertions(+)


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diff --git a/drivers/usb/host/uhci-hcd.h b/drivers/usb/host/uhci-hcd.h
index f1cc47292a59..7f9f33c8c232 100644
--- a/drivers/usb/host/uhci-hcd.h
+++ b/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);
diff --git a/drivers/usb/host/uhci-platform.c b/drivers/usb/host/uhci-platform.c
index 6cb16d4b2257..7d959071f92b 100644
--- a/drivers/usb/host/uhci-platform.c
+++ b/drivers/usb/host/uhci-platform.c
@@ -119,6 +119,21 @@ 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;
+        }
+	if (uhci->clk) {
+		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;