thermal: imx: Add support for reading OCOTP through nvmem

On newer imx SOCs accessing OCOTP directly is wrong because the ocotp
clock needs to be enabled first. Add support for reading those same
values through the nvmem API instead.

The older path is preserved for compatibility with older dts and because
it works correctly on imx6qdl chips.

Signed-off-by: Leonard Crestez <leonard.crestez@nxp.com>
Acked-by: Shawn Guo <shawnguo@kernel.org>
Signed-off-by: Zhang Rui <rui.zhang@intel.com>

drivers/thermal/imx_thermal.c

@@ -25,6 +25,7 @@
 #include <linux/slab.h>
 #include <linux/thermal.h>
 #include <linux/types.h>
+#include <linux/nvmem-consumer.h>
 
 #define REG_SET		0x4
 #define REG_CLR		0x8
@@ -94,7 +95,7 @@ struct imx_thermal_data {
 	struct thermal_cooling_device *cdev;
 	enum thermal_device_mode mode;
 	struct regmap *tempmon;
-	u32 c1, c2; /* See formula in imx_get_sensor_data() */
+	u32 c1, c2; /* See formula in imx_init_calib() */
 	int temp_passive;
 	int temp_critical;
 	int temp_max;
@@ -177,7 +178,7 @@ static int imx_get_temp(struct thermal_zone_device *tz, int *temp)
 
 	n_meas = (val & TEMPSENSE0_TEMP_CNT_MASK) >> TEMPSENSE0_TEMP_CNT_SHIFT;
 
-	/* See imx_get_sensor_data() for formula derivation */
+	/* See imx_init_calib() for formula derivation */
 	*temp = data->c2 - n_meas * data->c1;
 
 	/* Update alarm value to next higher trip point for TEMPMON_IMX6Q */
@@ -346,29 +347,12 @@ static struct thermal_zone_device_ops imx_tz_ops = {
 	.set_trip_temp = imx_set_trip_temp,
 };
 
-static int imx_get_sensor_data(struct platform_device *pdev)
+static int imx_init_calib(struct platform_device *pdev, u32 val)
 {
 	struct imx_thermal_data *data = platform_get_drvdata(pdev);
-	struct regmap *map;
 	int t1, n1;
-	int ret;
-	u32 val;
 	u64 temp64;
 
-	map = syscon_regmap_lookup_by_phandle(pdev->dev.of_node,
-					      "fsl,tempmon-data");
-	if (IS_ERR(map)) {
-		ret = PTR_ERR(map);
-		dev_err(&pdev->dev, "failed to get sensor regmap: %d\n", ret);
-		return ret;
-	}
-
-	ret = regmap_read(map, OCOTP_ANA1, &val);
-	if (ret) {
-		dev_err(&pdev->dev, "failed to read sensor data: %d\n", ret);
-		return ret;
-	}
-
 	if (val == 0 || val == ~0) {
 		dev_err(&pdev->dev, "invalid sensor calibration data\n");
 		return -EINVAL;
@@ -405,12 +389,12 @@ static int imx_get_sensor_data(struct platform_device *pdev)
 	data->c1 = temp64;
 	data->c2 = n1 * data->c1 + 1000 * t1;
 
-	/* use OTP for thermal grade */
-	ret = regmap_read(map, OCOTP_MEM0, &val);
-	if (ret) {
-		dev_err(&pdev->dev, "failed to read temp grade: %d\n", ret);
-		return ret;
-	}
+	return 0;
+}
+
+static void imx_init_temp_grade(struct platform_device *pdev, u32 val)
+{
+	struct imx_thermal_data *data = platform_get_drvdata(pdev);
 
 	/* The maximum die temp is specified by the Temperature Grade */
 	switch ((val >> 6) & 0x3) {
@@ -438,6 +422,55 @@ static int imx_get_sensor_data(struct platform_device *pdev)
 	 */
 	data->temp_critical = data->temp_max - (1000 * 5);
 	data->temp_passive = data->temp_max - (1000 * 10);
+}
+
+static int imx_init_from_tempmon_data(struct platform_device *pdev)
+{
+	struct regmap *map;
+	int ret;
+	u32 val;
+
+	map = syscon_regmap_lookup_by_phandle(pdev->dev.of_node,
+					      "fsl,tempmon-data");
+	if (IS_ERR(map)) {
+		ret = PTR_ERR(map);
+		dev_err(&pdev->dev, "failed to get sensor regmap: %d\n", ret);
+		return ret;
+	}
+
+	ret = regmap_read(map, OCOTP_ANA1, &val);
+	if (ret) {
+		dev_err(&pdev->dev, "failed to read sensor data: %d\n", ret);
+		return ret;
+	}
+	ret = imx_init_calib(pdev, val);
+	if (ret)
+		return ret;
+
+	ret = regmap_read(map, OCOTP_MEM0, &val);
+	if (ret) {
+		dev_err(&pdev->dev, "failed to read sensor data: %d\n", ret);
+		return ret;
+	}
+	imx_init_temp_grade(pdev, val);
+
+	return 0;
+}
+
+static int imx_init_from_nvmem_cells(struct platform_device *pdev)
+{
+	int ret;
+	u32 val;
+
+	ret = nvmem_cell_read_u32(&pdev->dev, "calib", &val);
+	if (ret)
+		return ret;
+	imx_init_calib(pdev, val);
+
+	ret = nvmem_cell_read_u32(&pdev->dev, "temp_grade", &val);
+	if (ret)
+		return ret;
+	imx_init_temp_grade(pdev, val);
 
 	return 0;
 }
@@ -514,10 +547,21 @@ static int imx_thermal_probe(struct platform_device *pdev)
 
 	platform_set_drvdata(pdev, data);
 
-	ret = imx_get_sensor_data(pdev);
-	if (ret) {
-		dev_err(&pdev->dev, "failed to get sensor data\n");
-		return ret;
+	if (of_find_property(pdev->dev.of_node, "nvmem-cells", NULL)) {
+		ret = imx_init_from_nvmem_cells(pdev);
+		if (ret == -EPROBE_DEFER)
+			return ret;
+		if (ret) {
+			dev_err(&pdev->dev, "failed to init from nvmem: %d\n",
+				ret);
+			return ret;
+		}
+	} else {
+		ret = imx_init_from_tempmon_data(pdev);
+		if (ret) {
+			dev_err(&pdev->dev, "failed to init from from fsl,tempmon-data\n");
+			return ret;
+		}
 	}
 
 	/* Make sure sensor is in known good state for measurements */