ARM: imx: add mmdc ipg clock operation for mmdc

[ Upstream commit 9454a0c ]

i.MX6 SoCs have MMDC ipg clock for registers access, to make
sure MMDC registers access successfully, add optional clock
enable for MMDC driver.

Signed-off-by: Anson Huang <Anson.Huang@nxp.com>
Signed-off-by: Shawn Guo <shawnguo@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>

arch/arm/mach-imx/mmdc.c

@@ -11,6 +11,7 @@
  * http://www.gnu.org/copyleft/gpl.html
  */
 
+#include <linux/clk.h>
 #include <linux/hrtimer.h>
 #include <linux/init.h>
 #include <linux/interrupt.h>
@@ -547,7 +548,20 @@ static int imx_mmdc_probe(struct platform_device *pdev)
 {
 	struct device_node *np = pdev->dev.of_node;
 	void __iomem *mmdc_base, *reg;
+	struct clk *mmdc_ipg_clk;
 	u32 val;
+	int err;
+
+	/* the ipg clock is optional */
+	mmdc_ipg_clk = devm_clk_get(&pdev->dev, NULL);
+	if (IS_ERR(mmdc_ipg_clk))
+		mmdc_ipg_clk = NULL;
+
+	err = clk_prepare_enable(mmdc_ipg_clk);
+	if (err) {
+		dev_err(&pdev->dev, "Unable to enable mmdc ipg clock.\n");
+		return err;
+	}
 
 	mmdc_base = of_iomap(np, 0);
 	WARN_ON(!mmdc_base);