arm: imx8mq: Add USB clock init function

Add clock function to setup relevant clocks for USB3.0 controllers and
PHYs on i.MX8MQ

Signed-off-by: Ye Li <ye.li@nxp.com>
Reviewed-by: Patrick Wildt <patrick@blueri.se>
Tested-by: Patrick Wildt <patrick@blueri.se>

arch/arm/include/asm/arch-imx8m/clock.h

@@ -257,6 +257,7 @@ u32 imx_get_uartclk(void);
 int clock_init(void);
 void init_clk_usdhc(u32 index);
 void init_uart_clk(u32 index);
+void init_usb_clk(void);
 void init_wdog_clk(void);
 unsigned int mxc_get_clock(enum mxc_clock clk);
 int clock_enable(enum clk_ccgr_index index, bool enable);

arch/arm/mach-imx/imx8m/clock_imx8mq.c

@@ -400,6 +400,28 @@ void init_wdog_clk(void)
 	clock_enable(CCGR_WDOG3, 1);
 }
 
+void init_usb_clk(void)
+{
+	if (!is_usb_boot()) {
+		clock_enable(CCGR_USB_CTRL1, 0);
+		clock_enable(CCGR_USB_CTRL2, 0);
+		clock_enable(CCGR_USB_PHY1, 0);
+		clock_enable(CCGR_USB_PHY2, 0);
+		/* 500MHz */
+		clock_set_target_val(USB_BUS_CLK_ROOT, CLK_ROOT_ON |
+				     CLK_ROOT_SOURCE_SEL(1));
+		/* 100MHz */
+		clock_set_target_val(USB_CORE_REF_CLK_ROOT, CLK_ROOT_ON |
+				     CLK_ROOT_SOURCE_SEL(1));
+		/* 100MHz */
+		clock_set_target_val(USB_PHY_REF_CLK_ROOT, CLK_ROOT_ON |
+				     CLK_ROOT_SOURCE_SEL(1));
+		clock_enable(CCGR_USB_CTRL1, 1);
+		clock_enable(CCGR_USB_CTRL2, 1);
+		clock_enable(CCGR_USB_PHY1, 1);
+		clock_enable(CCGR_USB_PHY2, 1);
+	}
+}
 
 void init_nand_clk(void)
 {