thermal: armada: Clarify control registers accesses

Bindings were incomplete for a long time by only exposing one of the two
available control registers. To ease the migration to the full bindings
(already in use for the Armada 375 SoC), rename the pointers for
clarification. This way, it will only be needed to add another pointer
to access the other control register when the time comes.

This avoids dangerous situations where the offset 0 of the control
area can be either one register or the other depending on the bindings
used. After this change, device trees of other SoCs could be migrated to
the "full" bindings if they may benefit from features from the
unaccessible register, without any change in the driver.

Signed-off-by: Miquel Raynal <miquel.raynal@free-electrons.com>
Reviewed-by: Gregory CLEMENT <gregory.clement@free-electrons.com>
Tested-by: Gregory CLEMENT <gregory.clement@free-electrons.com>
Signed-off-by: Eduardo Valentin <edubezval@gmail.com>

drivers/thermal/armada_thermal.c

@@ -39,12 +39,21 @@
 #define A375_HW_RESETn			BIT(8)
 #define A380_HW_RESET			BIT(8)
 
+/* Legacy bindings */
+#define LEGACY_CONTROL_MEM_LEN		0x4
+
+/* Current bindings with the 2 control registers under the same memory area */
+#define LEGACY_CONTROL1_OFFSET		0x0
+#define CONTROL0_OFFSET			0x0
+#define CONTROL1_OFFSET			0x4
+
 struct armada_thermal_data;
 
 /* Marvell EBU Thermal Sensor Dev Structure */
 struct armada_thermal_priv {
 	void __iomem *sensor;
-	void __iomem *control;
+	void __iomem *control0;
+	void __iomem *control1;
 	struct armada_thermal_data *data;
 };
 
@@ -66,27 +75,28 @@ struct armada_thermal_data {
 	unsigned int temp_shift;
 	unsigned int temp_mask;
 	u32 is_valid_bit;
+	bool needs_control0;
 };
 
 static void armadaxp_init_sensor(struct platform_device *pdev,
 				 struct armada_thermal_priv *priv)
 {
-	unsigned long reg;
+	u32 reg;
 
-	reg = readl_relaxed(priv->control);
+	reg = readl_relaxed(priv->control1);
 	reg |= PMU_TDC0_OTF_CAL_MASK;
-	writel(reg, priv->control);
+	writel(reg, priv->control1);
 
 	/* Reference calibration value */
 	reg &= ~PMU_TDC0_REF_CAL_CNT_MASK;
 	reg |= (0xf1 << PMU_TDC0_REF_CAL_CNT_OFFS);
-	writel(reg, priv->control);
+	writel(reg, priv->control1);
 
 	/* Reset the sensor */
-	reg = readl_relaxed(priv->control);
-	writel((reg | PMU_TDC0_SW_RST_MASK), priv->control);
+	reg = readl_relaxed(priv->control1);
+	writel((reg | PMU_TDC0_SW_RST_MASK), priv->control1);
 
-	writel(reg, priv->control);
+	writel(reg, priv->control1);
 
 	/* Enable the sensor */
 	reg = readl_relaxed(priv->sensor);
@@ -97,19 +107,19 @@ static void armadaxp_init_sensor(struct platform_device *pdev,
 static void armada370_init_sensor(struct platform_device *pdev,
 				  struct armada_thermal_priv *priv)
 {
-	unsigned long reg;
+	u32 reg;
 
-	reg = readl_relaxed(priv->control);
+	reg = readl_relaxed(priv->control1);
 	reg |= PMU_TDC0_OTF_CAL_MASK;
-	writel(reg, priv->control);
+	writel(reg, priv->control1);
 
 	/* Reference calibration value */
 	reg &= ~PMU_TDC0_REF_CAL_CNT_MASK;
 	reg |= (0xf1 << PMU_TDC0_REF_CAL_CNT_OFFS);
-	writel(reg, priv->control);
+	writel(reg, priv->control1);
 
 	reg &= ~PMU_TDC0_START_CAL_MASK;
-	writel(reg, priv->control);
+	writel(reg, priv->control1);
 
 	msleep(10);
 }
@@ -117,30 +127,30 @@ static void armada370_init_sensor(struct platform_device *pdev,
 static void armada375_init_sensor(struct platform_device *pdev,
 				  struct armada_thermal_priv *priv)
 {
-	unsigned long reg;
+	u32 reg;
 
-	reg = readl(priv->control + 4);
+	reg = readl(priv->control1);
 	reg &= ~(A375_UNIT_CONTROL_MASK << A375_UNIT_CONTROL_SHIFT);
 	reg &= ~A375_READOUT_INVERT;
 	reg &= ~A375_HW_RESETn;
 
-	writel(reg, priv->control + 4);
+	writel(reg, priv->control1);
 	msleep(20);
 
 	reg |= A375_HW_RESETn;
-	writel(reg, priv->control + 4);
+	writel(reg, priv->control1);
 	msleep(50);
 }
 
 static void armada380_init_sensor(struct platform_device *pdev,
 				  struct armada_thermal_priv *priv)
 {
-	unsigned long reg = readl_relaxed(priv->control);
+	u32 reg = readl_relaxed(priv->control1);
 
 	/* Reset hardware once */
 	if (!(reg & A380_HW_RESET)) {
 		reg |= A380_HW_RESET;
-		writel(reg, priv->control);
+		writel(reg, priv->control1);
 		msleep(10);
 	}
 }
@@ -214,6 +224,7 @@ static const struct armada_thermal_data armada375_data = {
 	.coef_b = 3171900000UL,
 	.coef_m = 10000000UL,
 	.coef_div = 13616,
+	.needs_control0 = true,
 };
 
 static const struct armada_thermal_data armada380_data = {
@@ -253,6 +264,7 @@ MODULE_DEVICE_TABLE(of, armada_thermal_id_table);
 
 static int armada_thermal_probe(struct platform_device *pdev)
 {
+	void __iomem *control = NULL;
 	struct thermal_zone_device *thermal;
 	const struct of_device_id *match;
 	struct armada_thermal_priv *priv;
@@ -272,11 +284,31 @@ static int armada_thermal_probe(struct platform_device *pdev)
 		return PTR_ERR(priv->sensor);
 
 	res = platform_get_resource(pdev, IORESOURCE_MEM, 1);
-	priv->control = devm_ioremap_resource(&pdev->dev, res);
-	if (IS_ERR(priv->control))
-		return PTR_ERR(priv->control);
+	control = devm_ioremap_resource(&pdev->dev, res);
+	if (IS_ERR(control))
+		return PTR_ERR(control);
 
 	priv->data = (struct armada_thermal_data *)match->data;
+
+	/*
+	 * Legacy DT bindings only described "control1" register (also referred
+	 * as "control MSB" on old documentation). New bindings cover
+	 * "control0/control LSB" and "control1/control MSB" registers within
+	 * the same resource, which is then of size 8 instead of 4.
+	 */
+	if (resource_size(res) == LEGACY_CONTROL_MEM_LEN) {
+		/* ->control0 unavailable in this configuration */
+		if (priv->data->needs_control0) {
+			dev_err(&pdev->dev, "No access to control0 register\n");
+			return -EINVAL;
+		}
+
+		priv->control1 = control + LEGACY_CONTROL1_OFFSET;
+	} else {
+		priv->control0 = control + CONTROL0_OFFSET;
+		priv->control1 = control + CONTROL1_OFFSET;
+	}
+
 	priv->data->init_sensor(pdev, priv);
 
 	thermal = thermal_zone_device_register("armada_thermal", 0, 0,