power: reset: syscon-poweroff: add a mask property

Make the syscon-poweroff driver accept value and mask instead of
just value.

Prior to this patch, the property name for the value was 'mask'. If
only the mask property is defined on a node, maintain compatibility
by using it as the value.

Signed-off-by: Guy Shapiro <guy.shapiro@mobi-wize.com>
Acked-by: Rob Herring <robh@kernel.org>
Signed-off-by: Sebastian Reichel <sre@kernel.org>

Author: Guy Shapiro

Documentation/devicetree/bindings/power/reset/syscon-poweroff.txt

@@ -3,13 +3,20 @@ Generic SYSCON mapped register poweroff driver
 This is a generic poweroff driver using syscon to map the poweroff register.
 The poweroff is generally performed with a write to the poweroff register
 defined by the register map pointed by syscon reference plus the offset
-with the mask defined in the poweroff node.
+with the value and mask defined in the poweroff node.
 
 Required properties:
 - compatible: should contain "syscon-poweroff"
 - regmap: this is phandle to the register map node
 - offset: offset in the register map for the poweroff register (in bytes)
-- mask: the poweroff value written to the poweroff register (32 bit access)
+- value: the poweroff value written to the poweroff register (32 bit access)
+
+Optional properties:
+- mask: update only the register bits defined by the mask (32 bit)
+
+Legacy usage:
+If a node doesn't contain a value property but contains a mask property, the
+mask property is used as the value.
 
 Default will be little endian mode, 32 bit access only.
 

drivers/power/reset/syscon-poweroff.c

@@ -28,12 +28,13 @@
 
 static struct regmap *map;
 static u32 offset;
+static u32 value;
 static u32 mask;
 
 static void syscon_poweroff(void)
 {
 	/* Issue the poweroff */
-	regmap_write(map, offset, mask);
+	regmap_update_bits(map, offset, mask, value);
 
 	mdelay(1000);
 
@@ -43,6 +44,7 @@ static void syscon_poweroff(void)
 static int syscon_poweroff_probe(struct platform_device *pdev)
 {
 	char symname[KSYM_NAME_LEN];
+	int mask_err, value_err;
 
 	map = syscon_regmap_lookup_by_phandle(pdev->dev.of_node, "regmap");
 	if (IS_ERR(map)) {
@@ -55,11 +57,22 @@ static int syscon_poweroff_probe(struct platform_device *pdev)
 		return -EINVAL;
 	}
 
-	if (of_property_read_u32(pdev->dev.of_node, "mask", &mask)) {
-		dev_err(&pdev->dev, "unable to read 'mask'");
+	value_err = of_property_read_u32(pdev->dev.of_node, "value", &value);
+	mask_err = of_property_read_u32(pdev->dev.of_node, "mask", &mask);
+	if (value_err && mask_err) {
+		dev_err(&pdev->dev, "unable to read 'value' and 'mask'");
 		return -EINVAL;
 	}
 
+	if (value_err) {
+		/* support old binding */
+		value = mask;
+		mask = 0xFFFFFFFF;
+	} else if (mask_err) {
+		/* support value without mask*/
+		mask = 0xFFFFFFFF;
+	}
+
 	if (pm_power_off) {
 		lookup_symbol_name((ulong)pm_power_off, symname);
 		dev_err(&pdev->dev,