soc: imx8m: Enable OCOTP clock for imx8mm before reading registers

Commit 836fb30 ("soc: imx8m: Enable OCOTP clock before reading the
register") added configuration to enable the OCOTP clock before
attempting to read from the associated registers.

This same kexec issue is present with the imx8m SoCs that use the
imx8mm_soc_uid function (e.g. imx8mp). This requires the imx8mm_soc_uid
function to configure the OCOTP clock before accessing the associated
registers. This change implements the same clock enable functionality
that is present in the imx8mq_soc_revision function for the
imx8mm_soc_uid function.

Signed-off-by: Nathan Rossi <nathan.rossi@digi.com>
Reviewed-by: Fabio Estevam <festevam@gmail.com>
Fixes: 836fb30 ("soc: imx8m: Enable OCOTP clock before reading the register")
Signed-off-by: Shawn Guo <shawnguo@kernel.org>

Author: Nathan Rossi

drivers/soc/imx/soc-imx8m.c

@@ -100,6 +100,7 @@ static void __init imx8mm_soc_uid(void)
 {
 	void __iomem *ocotp_base;
 	struct device_node *np;
+	struct clk *clk;
 	u32 offset = of_machine_is_compatible("fsl,imx8mp") ?
 		     IMX8MP_OCOTP_UID_OFFSET : 0;
 
@@ -109,11 +110,20 @@ static void __init imx8mm_soc_uid(void)
 
 	ocotp_base = of_iomap(np, 0);
 	WARN_ON(!ocotp_base);
+	clk = of_clk_get_by_name(np, NULL);
+	if (IS_ERR(clk)) {
+		WARN_ON(IS_ERR(clk));
+		return;
+	}
+
+	clk_prepare_enable(clk);
 
 	soc_uid = readl_relaxed(ocotp_base + OCOTP_UID_HIGH + offset);
 	soc_uid <<= 32;
 	soc_uid |= readl_relaxed(ocotp_base + OCOTP_UID_LOW + offset);
 
+	clk_disable_unprepare(clk);
+	clk_put(clk);
 	iounmap(ocotp_base);
 	of_node_put(np);
 }