mfd: sec-core: Disable buck voltage reset on watchdog falling edge

The WRSTBI bit (disabled by default but enabled by bootloader), when
set, is responsible for resetting voltages to default values of
certain bucks on falling edge of Warm Reset Input pin from AP.

However on some boards (with S2MPS13) the pin is pulled down so any
suspend will effectively trigger the reset of bucks supplying the power
to the little and big cores. In the same time when resuming, these bucks
must provide voltage greater or equal to voltage before suspend to match
the frequency chosen by cpufreq. If voltage (default value of voltage
after reset) is lower than one set by cpufreq before suspend, then
system will hang during resuming.

Signed-off-by: Krzysztof Kozlowski <k.kozlowski@samsung.com>
Reported-by: Bartlomiej Zolnierkiewicz <b.zolnierkie@samsung.com>
Tested-by: Bartlomiej Zolnierkiewicz <b.zolnierkie@samsung.com>
Signed-off-by: Lee Jones <lee.jones@linaro.org>

1 files changed, 26 insertions, 0 deletions

diff --git a/drivers/mfd/sec-core.c b/drivers/mfd/sec-core.c
index 589e5efc2d7f..2626fc0b5b8c 100644
--- a/drivers/mfd/sec-core.c
+++ b/drivers/mfd/sec-core.c
@@ -262,6 +262,29 @@ static void sec_pmic_dump_rev(struct sec_pmic_dev *sec_pmic)
 		dev_dbg(sec_pmic->dev, "Revision: 0x%x\n", val);
 }
 
+static void sec_pmic_configure(struct sec_pmic_dev *sec_pmic)
+{
+	int err;
+
+	if (sec_pmic->device_type != S2MPS13X)
+		return;
+
+	if (sec_pmic->pdata->disable_wrstbi) {
+		/*
+		 * If WRSTBI pin is pulled down this feature must be disabled
+		 * because each Suspend to RAM will trigger buck voltage reset
+		 * to default values.
+		 */
+		err = regmap_update_bits(sec_pmic->regmap_pmic,
+					 S2MPS13_REG_WRSTBI,
+					 S2MPS13_REG_WRSTBI_MASK, 0x0);
+		if (err)
+			dev_warn(sec_pmic->dev,
+				 "Cannot initialize WRSTBI config: %d\n",
+				 err);
+	}
+}
+
 #ifdef CONFIG_OF
 /*
  * Only the common platform data elements for s5m8767 are parsed here from the
@@ -289,6 +312,8 @@ static struct sec_platform_data *sec_pmic_i2c_parse_dt_pdata(
 
 	pd->manual_poweroff = of_property_read_bool(dev->of_node,
 						"samsung,s2mps11-acokb-ground");
+	pd->disable_wrstbi = of_property_read_bool(dev->of_node,
+						"samsung,s2mps11-wrstbi-ground");
 	return pd;
 }
 #else
@@ -434,6 +459,7 @@ static int sec_pmic_probe(struct i2c_client *i2c,
 		goto err_mfd;
 
 	device_init_wakeup(sec_pmic->dev, sec_pmic->wakeup);
+	sec_pmic_configure(sec_pmic);
 	sec_pmic_dump_rev(sec_pmic);
 
 	return ret;