linux-kernel - [PATCH 2/2] cpufreq: imx6q: read OCOTP through nvmem for imx6ul/imx6ull

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Date:   Fri, 14 Sep 2018 10:59:22 +0800
From:   Anson Huang <Anson.Huang@....com>
To:     shawnguo@...nel.org, s.hauer@...gutronix.de, kernel@...gutronix.de,
        fabio.estevam@....com, robh+dt@...nel.org, mark.rutland@....com,
        rjw@...ysocki.net, viresh.kumar@...aro.org,
        linux-arm-kernel@...ts.infradead.org, devicetree@...r.kernel.org,
        linux-kernel@...r.kernel.org, linux-pm@...r.kernel.org
Cc:     Linux-imx@....com
Subject: [PATCH 2/2] cpufreq: imx6q: read OCOTP through nvmem for imx6ul/imx6ull

On i.MX6UL/i.MX6ULL, accessing OCOTP directly is wrong because
the ocotp clock needs to be enabled first. Add support for reading
OCOTP through the nvmem API instead.

Signed-off-by: Anson Huang <Anson.Huang@....com>
---
 drivers/cpufreq/imx6q-cpufreq.c | 39 +++++++++++++++++++--------------------
 1 file changed, 19 insertions(+), 20 deletions(-)

diff --git a/drivers/cpufreq/imx6q-cpufreq.c b/drivers/cpufreq/imx6q-cpufreq.c
index b2ff423..4ae6c74 100644
--- a/drivers/cpufreq/imx6q-cpufreq.c
+++ b/drivers/cpufreq/imx6q-cpufreq.c
@@ -12,6 +12,7 @@
 #include <linux/cpu_cooling.h>
 #include <linux/err.h>
 #include <linux/module.h>
+#include <linux/nvmem-consumer.h>
 #include <linux/of.h>
 #include <linux/of_address.h>
 #include <linux/pm_opp.h>
@@ -290,22 +291,11 @@ static void imx6q_opp_check_speed_grading(struct device *dev)
 #define OCOTP_CFG3_6ULL_SPEED_792MHZ	0x2
 #define OCOTP_CFG3_6ULL_SPEED_900MHZ	0x3
 
-static void imx6ul_opp_check_speed_grading(struct device *dev)
+static int imx6ul_opp_check_speed_grading(struct device *dev)
 {
-	struct device_node *np;
-	void __iomem *base;
+	int ret;
 	u32 val;
 
-	np = of_find_compatible_node(NULL, NULL, "fsl,imx6ul-ocotp");
-	if (!np)
-		return;
-
-	base = of_iomap(np, 0);
-	if (!base) {
-		dev_err(dev, "failed to map ocotp\n");
-		goto put_node;
-	}
-
 	/*
 	 * Speed GRADING[1:0] defines the max speed of ARM:
 	 * 2b'00: Reserved;
@@ -314,7 +304,10 @@ static void imx6ul_opp_check_speed_grading(struct device *dev)
 	 * 2b'11: 900000000Hz on i.MX6ULL only;
 	 * We need to set the max speed of ARM according to fuse map.
 	 */
-	val = readl_relaxed(base + OCOTP_CFG3);
+	ret = nvmem_cell_read_u32(dev, "speed_grade", &val);
+	if (ret)
+		return ret;
+
 	val >>= OCOTP_CFG3_SPEED_SHIFT;
 	val &= 0x3;
 
@@ -334,9 +327,7 @@ static void imx6ul_opp_check_speed_grading(struct device *dev)
 				dev_warn(dev, "failed to disable 900MHz OPP\n");
 	}
 
-	iounmap(base);
-put_node:
-	of_node_put(np);
+	return ret;
 }
 
 static int imx6q_cpufreq_probe(struct platform_device *pdev)
@@ -394,10 +385,18 @@ static int imx6q_cpufreq_probe(struct platform_device *pdev)
 	}
 
 	if (of_machine_is_compatible("fsl,imx6ul") ||
-	    of_machine_is_compatible("fsl,imx6ull"))
-		imx6ul_opp_check_speed_grading(cpu_dev);
-	else
+	    of_machine_is_compatible("fsl,imx6ull")) {
+		ret = imx6ul_opp_check_speed_grading(cpu_dev);
+		if (ret == -EPROBE_DEFER)
+			return ret;
+		if (ret) {
+			dev_err(cpu_dev, "failed to read from nvmem: %d\n",
+				ret);
+			return ret;
+		}
+	} else {
 		imx6q_opp_check_speed_grading(cpu_dev);
+	}
 
 	/* Because we have added the OPPs here, we must free them */
 	free_opp = true;
-- 
2.7.4