regulator: tps6586x: add support for SYS rail

Device have SYS rail which is always ON. It is system power bus. LDO5
and LDO_RTC get powered through this rail internally. Add support for
this rail and make the LDO5/LDO_RTC supply by it. Update document
accordingly.

[swarren: Instantiate the sys regulator from board-harmony-power.c to
 avoid regression.]

Signed-off-by: Laxman Dewangan <ldewangan@nvidia.com>
Signed-off-by: Stephen Warren <swarren@nvidia.com>
Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com>
diff --git a/drivers/mfd/tps6586x.c b/drivers/mfd/tps6586x.c
index 353c348..380a3c8 100644
--- a/drivers/mfd/tps6586x.c
+++ b/drivers/mfd/tps6586x.c
@@ -25,6 +25,7 @@
 #include <linux/i2c.h>
 #include <linux/regmap.h>
 #include <linux/regulator/of_regulator.h>
+#include <linux/regulator/machine.h>
 
 #include <linux/mfd/core.h>
 #include <linux/mfd/tps6586x.h>
@@ -346,6 +347,7 @@
 
 #ifdef CONFIG_OF
 static struct of_regulator_match tps6586x_matches[] = {
+	{ .name = "sys",     .driver_data = (void *)TPS6586X_ID_SYS     },
 	{ .name = "sm0",     .driver_data = (void *)TPS6586X_ID_SM_0    },
 	{ .name = "sm1",     .driver_data = (void *)TPS6586X_ID_SM_1    },
 	{ .name = "sm2",     .driver_data = (void *)TPS6586X_ID_SM_2    },
@@ -369,6 +371,7 @@
 	struct tps6586x_platform_data *pdata;
 	struct tps6586x_subdev_info *devs;
 	struct device_node *regs;
+	const char *sys_rail_name = NULL;
 	unsigned int count;
 	unsigned int i, j;
 	int err;
@@ -391,12 +394,22 @@
 		return NULL;
 
 	for (i = 0, j = 0; i < num && j < count; i++) {
+		struct regulator_init_data *reg_idata;
+
 		if (!tps6586x_matches[i].init_data)
 			continue;
 
+		reg_idata  = tps6586x_matches[i].init_data;
 		devs[j].name = "tps6586x-regulator";
 		devs[j].platform_data = tps6586x_matches[i].init_data;
 		devs[j].id = (int)tps6586x_matches[i].driver_data;
+		if (devs[j].id == TPS6586X_ID_SYS)
+			sys_rail_name = reg_idata->constraints.name;
+
+		if ((devs[j].id == TPS6586X_ID_LDO_5) ||
+			(devs[j].id == TPS6586X_ID_LDO_RTC))
+			reg_idata->supply_regulator = sys_rail_name;
+
 		devs[j].of_node = tps6586x_matches[i].of_node;
 		j++;
 	}