USB: ehci-atmel: add usb_clk for transition to CCF

The AT91 PMC (Power Management Controller) provides a USB clock used by
the different USB controllers (ehci, ohci and udc).
The atmel-ehci driver must configure the usb clock rate to 48Mhz in order
to get a fully functionnal USB host controller.
This configuration was formely done in mach-at91/clock.c, but will be
bypassed when moving to common clk framework.

This patch adds support for usb clock retrieval and configuration only if
CCF is enabled (CONFIG_COMMON_CLK).

Signed-off-by: Boris BREZILLON <b.brezillon@overkiz.com>
Cc: Nicolas Ferre <nicolas.ferre@atmel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/usb/host/ehci-atmel.c

@@ -30,13 +30,17 @@ static const char hcd_name[] = "ehci-atmel";
 static struct hc_driver __read_mostly ehci_atmel_hc_driver;
 
 /* interface and function clocks */
-static struct clk *iclk, *fclk;
+static struct clk *iclk, *fclk, *uclk;
 static int clocked;
 
 /*-------------------------------------------------------------------------*/
 
 static void atmel_start_clock(void)
 {
+	if (IS_ENABLED(CONFIG_COMMON_CLK)) {
+		clk_set_rate(uclk, 48000000);
+		clk_prepare_enable(uclk);
+	}
 	clk_prepare_enable(iclk);
 	clk_prepare_enable(fclk);
 	clocked = 1;
@@ -46,6 +50,8 @@ static void atmel_stop_clock(void)
 {
 	clk_disable_unprepare(fclk);
 	clk_disable_unprepare(iclk);
+	if (IS_ENABLED(CONFIG_COMMON_CLK))
+		clk_disable_unprepare(uclk);
 	clocked = 0;
 }
 
@@ -130,6 +136,14 @@ static int ehci_atmel_drv_probe(struct platform_device *pdev)
 		retval = -ENOENT;
 		goto fail_request_resource;
 	}
+	if (IS_ENABLED(CONFIG_COMMON_CLK)) {
+		uclk = devm_clk_get(&pdev->dev, "usb_clk");
+		if (IS_ERR(uclk)) {
+			dev_err(&pdev->dev, "failed to get uclk\n");
+			retval = PTR_ERR(uclk);
+			goto fail_request_resource;
+		}
+	}
 
 	ehci = hcd_to_ehci(hcd);
 	/* registers start at offset 0x0 */