Add support for bq27521 battery monitor

This adds basic support for BQ27521 battery monitor, used in Nokia N9
and N950. In particular, battery voltage is important to be able to
tell when the battery is almost empty. Emptying battery on N950 is
pretty painful, as flasher needs to be used to recover phone in such case.

Signed-off-by: Pavel Machek <pavel@ucw.cz>
Acked-by: Andrew F. Davis <afd@ti.com>
Acked-by: Rob Herring <robh@kernel.org>
Signed-off-by: Sebastian Reichel <sebastian.reichel@collabora.co.uk>

Documentation/devicetree/bindings/power/supply/bq27xxx.txt

@@ -15,6 +15,7 @@ Required properties:
  * "ti,bq27520g2" - BQ27520-g2
  * "ti,bq27520g3" - BQ27520-g3
  * "ti,bq27520g4" - BQ27520-g4
+ * "ti,bq27521" - BQ27521
  * "ti,bq27530" - BQ27530
  * "ti,bq27531" - BQ27531
  * "ti,bq27541" - BQ27541

drivers/power/supply/bq27xxx_battery.c

@@ -323,6 +323,30 @@ static u8
 		[BQ27XXX_REG_AP] = INVALID_REG_ADDR,
 		BQ27XXX_DM_REG_ROWS,
 	},
+	bq27521_regs[BQ27XXX_REG_MAX] = {
+		[BQ27XXX_REG_CTRL] = 0x02,
+		[BQ27XXX_REG_TEMP] = 0x0a,
+		[BQ27XXX_REG_INT_TEMP] = INVALID_REG_ADDR,
+		[BQ27XXX_REG_VOLT] = 0x0c,
+		[BQ27XXX_REG_AI] = 0x0e,
+		[BQ27XXX_REG_FLAGS] = 0x08,
+		[BQ27XXX_REG_TTE] = INVALID_REG_ADDR,
+		[BQ27XXX_REG_TTF] = INVALID_REG_ADDR,
+		[BQ27XXX_REG_TTES] = INVALID_REG_ADDR,
+		[BQ27XXX_REG_TTECP] = INVALID_REG_ADDR,
+		[BQ27XXX_REG_NAC] = INVALID_REG_ADDR,
+		[BQ27XXX_REG_FCC] = INVALID_REG_ADDR,
+		[BQ27XXX_REG_CYCT] = INVALID_REG_ADDR,
+		[BQ27XXX_REG_AE] = INVALID_REG_ADDR,
+		[BQ27XXX_REG_SOC] = INVALID_REG_ADDR,
+		[BQ27XXX_REG_DCAP] = INVALID_REG_ADDR,
+		[BQ27XXX_REG_AP] = INVALID_REG_ADDR,
+		[BQ27XXX_DM_CTRL] = INVALID_REG_ADDR,
+		[BQ27XXX_DM_CLASS] = INVALID_REG_ADDR,
+		[BQ27XXX_DM_BLOCK] = INVALID_REG_ADDR,
+		[BQ27XXX_DM_DATA] = INVALID_REG_ADDR,
+		[BQ27XXX_DM_CKSUM] = INVALID_REG_ADDR,
+	},
 	bq27530_regs[BQ27XXX_REG_MAX] = {
 		[BQ27XXX_REG_CTRL] = 0x00,
 		[BQ27XXX_REG_TEMP] = 0x06,
@@ -557,6 +581,15 @@ static enum power_supply_property bq27520g4_props[] = {
 	POWER_SUPPLY_PROP_MANUFACTURER,
 };
 
+static enum power_supply_property bq27521_props[] = {
+	POWER_SUPPLY_PROP_STATUS,
+	POWER_SUPPLY_PROP_PRESENT,
+	POWER_SUPPLY_PROP_VOLTAGE_NOW,
+	POWER_SUPPLY_PROP_CURRENT_NOW,
+	POWER_SUPPLY_PROP_TEMP,
+	POWER_SUPPLY_PROP_TECHNOLOGY,
+};
+
 static enum power_supply_property bq27530_props[] = {
 	POWER_SUPPLY_PROP_STATUS,
 	POWER_SUPPLY_PROP_PRESENT,
@@ -671,6 +704,7 @@ static struct bq27xxx_dm_reg bq27500_dm_regs[] = {
 #define bq27520g2_dm_regs 0
 #define bq27520g3_dm_regs 0
 #define bq27520g4_dm_regs 0
+#define bq27521_dm_regs 0
 #define bq27530_dm_regs 0
 #define bq27531_dm_regs 0
 #define bq27541_dm_regs 0
@@ -717,8 +751,8 @@ static struct bq27xxx_dm_reg bq27621_dm_regs[] = {
 #endif
 
 #define BQ27XXX_O_ZERO	0x00000001
-#define BQ27XXX_O_OTDC	0x00000002
-#define BQ27XXX_O_UTOT  0x00000004
+#define BQ27XXX_O_OTDC	0x00000002 /* has OTC/OTD overtemperature flags */
+#define BQ27XXX_O_UTOT  0x00000004 /* has OT overtemperature flag */
 #define BQ27XXX_O_CFGUP	0x00000008
 #define BQ27XXX_O_RAM	0x00000010
 
@@ -751,6 +785,7 @@ static struct {
 	[BQ27520G2] = BQ27XXX_DATA(bq27520g2, 0         , BQ27XXX_O_OTDC),
 	[BQ27520G3] = BQ27XXX_DATA(bq27520g3, 0         , BQ27XXX_O_OTDC),
 	[BQ27520G4] = BQ27XXX_DATA(bq27520g4, 0         , BQ27XXX_O_OTDC),
+	[BQ27521]   = BQ27XXX_DATA(bq27521,   0         , 0),
 	[BQ27530]   = BQ27XXX_DATA(bq27530,   0         , BQ27XXX_O_UTOT),
 	[BQ27531]   = BQ27XXX_DATA(bq27531,   0         , BQ27XXX_O_UTOT),
 	[BQ27541]   = BQ27XXX_DATA(bq27541,   0         , BQ27XXX_O_OTDC),

drivers/power/supply/bq27xxx_battery_i2c.c

@@ -239,6 +239,7 @@ static const struct i2c_device_id bq27xxx_i2c_id_table[] = {
 	{ "bq27520g2", BQ27520G2 },
 	{ "bq27520g3", BQ27520G3 },
 	{ "bq27520g4", BQ27520G4 },
+	{ "bq27521", BQ27521 },
 	{ "bq27530", BQ27530 },
 	{ "bq27531", BQ27531 },
 	{ "bq27541", BQ27541 },
@@ -269,6 +270,7 @@ static const struct of_device_id bq27xxx_battery_i2c_of_match_table[] = {
 	{ .compatible = "ti,bq27520g2" },
 	{ .compatible = "ti,bq27520g3" },
 	{ .compatible = "ti,bq27520g4" },
+	{ .compatible = "ti,bq27521" },
 	{ .compatible = "ti,bq27530" },
 	{ .compatible = "ti,bq27531" },
 	{ .compatible = "ti,bq27541" },

include/linux/power/bq27xxx_battery.h

@@ -16,6 +16,7 @@ enum bq27xxx_chip {
 	BQ27520G2, /* bq27520G2 */
 	BQ27520G3, /* bq27520G3 */
 	BQ27520G4, /* bq27520G4 */
+	BQ27521, /* bq27521 */
 	BQ27530, /* bq27530, bq27531 */
 	BQ27531,
 	BQ27541, /* bq27541, bq27542, bq27546, bq27742 */