linux-kernel - [PATCH] soc: imx8m: Enable OCOTP clock for imx8mm before reading registers

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Message-Id: <20230814015700.70156-1-nathan@nathanrossi.com>
Date:   Mon, 14 Aug 2023 01:57:00 +0000
From:   Nathan Rossi <nathan@...hanrossi.com>
To:     linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org
Cc:     Nathan Rossi <nathan@...hanrossi.com>,
        Nathan Rossi <nathan.rossi@...i.com>,
        Shawn Guo <shawnguo@...nel.org>,
        Sascha Hauer <s.hauer@...gutronix.de>,
        Pengutronix Kernel Team <kernel@...gutronix.de>,
        Fabio Estevam <festevam@...il.com>,
        NXP Linux Team <linux-imx@....com>
Subject: [PATCH] soc: imx8m: Enable OCOTP clock for imx8mm before reading registers

From: Nathan Rossi <nathan.rossi@...i.com>

Commit 836fb30949d9 ("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@...i.com>
---
 drivers/soc/imx/soc-imx8m.c | 10 ++++++++++
 1 file changed, 10 insertions(+)

diff --git a/drivers/soc/imx/soc-imx8m.c b/drivers/soc/imx/soc-imx8m.c
index 1dcd243df5..ec87d9d878 100644
--- a/drivers/soc/imx/soc-imx8m.c
+++ b/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);
 }
---
2.40.1