[PATCH v4] mfd: rk808: add reboot support to rk808.c

[Peter Geis]

This adds reboot support to the rk808 pmic driver and enables it for
the rk809 and rk817 devices.
This only enables if the rockchip,system-power-controller flag is set.

Signed-off-by: Peter Geis <pgwipeout at gmail.com>
Signed-off-by: Frank Wunderlich <frank-w at public-files.de>
Reviewed-by: Dmitry Osipenko <digetx at gmail.com>
---
(Resending due to incorrect Subject line)

This patch was created to address issues with psci-reset on rk356x
chips. Until the rk356x series ATF open source code is released so we
can fix the issue at the source, this is the only way to ensure reliable
resetting on devices using these chips.

After testing the rk808 (thanks Robin!), it was found DEV_OFF_RST does
not reset the PMIC to a power on state. Since the rk805 and rk818 match
this register layout, I'm removing support for all three in the v2.
It may be possible to add support to them using an RTC wakeup, but that
has not been explored and is outside the scope of this patch.

Changelog:
V4:
- reorder rk808_restart_notify (Thanks Dmitry)
- drop of_property_read_bool before unregister (Good catch Frank)

V3: Thanks Dmitry!
- Adjust priority to be in line with other pmic drivers
- Move ret handling to case switch
- Make default registration debug
- Add unregister function on removal

V2:
- Squash the patch from Frank Wunderlich for rk809 support.
- Remove support for the rk805, rk808, and rk818 devices.
- Only register the reset handler for supported devices.
- Remove unnecessary dev_err and dev_warn statements.
- Register the reset handler directly

 drivers/mfd/rk808.c       | 44 +++++++++++++++++++++++++++++++++++++++
 include/linux/mfd/rk808.h |  1 +
 2 files changed, 45 insertions(+)

diff --git a/drivers/mfd/rk808.c b/drivers/mfd/rk808.c
index b181fe401330..874d461dda44 100644
--- a/drivers/mfd/rk808.c
+++ b/drivers/mfd/rk808.c
@@ -19,6 +19,7 @@
 #include <linux/module.h>
 #include <linux/of_device.h>
 #include <linux/regmap.h>
+#include <linux/reboot.h>
 
 struct rk808_reg_data {
 	int addr;
@@ -543,6 +544,7 @@ static void rk808_pm_power_off(void)
 		reg = RK808_DEVCTRL_REG,
 		bit = DEV_OFF_RST;
 		break;
+	case RK809_ID:
 	case RK817_ID:
 		reg = RK817_SYS_CFG(3);
 		bit = DEV_OFF;
@@ -559,6 +561,34 @@ static void rk808_pm_power_off(void)
 		dev_err(&rk808_i2c_client->dev, "Failed to shutdown device!\n");
 }
 
+static int rk808_restart_notify(struct notifier_block *this, unsigned long mode, void *cmd)
+{
+	struct rk808 *rk808 = i2c_get_clientdata(rk808_i2c_client);
+	unsigned int reg, bit;
+	int ret;
+
+	switch (rk808->variant) {
+	case RK809_ID:
+	case RK817_ID:
+		reg = RK817_SYS_CFG(3);
+		bit = DEV_RST;
+		break;
+
+	default:
+		return NOTIFY_DONE;
+	}
+	ret = regmap_update_bits(rk808->regmap, reg, bit, bit);
+	if (ret)
+		dev_err(&rk808_i2c_client->dev, "Failed to restart device!\n");
+
+	return NOTIFY_DONE;
+}
+
+static struct notifier_block rk808_restart_handler = {
+	.notifier_call = rk808_restart_notify,
+	.priority = 192,
+};
+
 static void rk8xx_shutdown(struct i2c_client *client)
 {
 	struct rk808 *rk808 = i2c_get_clientdata(client);
@@ -727,6 +757,18 @@ static int rk808_probe(struct i2c_client *client,
 	if (of_property_read_bool(np, "rockchip,system-power-controller")) {
 		rk808_i2c_client = client;
 		pm_power_off = rk808_pm_power_off;
+
+		switch (rk808->variant) {
+		case RK809_ID:
+		case RK817_ID:
+			ret = register_restart_handler(&rk808_restart_handler);
+			if (ret)
+				dev_warn(&client->dev, "failed to register restart handler, %d\n", ret);
+			break;
+		default:
+			dev_dbg(&client->dev, "pmic controlled board reset not supported\n");
+			break;
+		}
 	}
 
 	return 0;
@@ -749,6 +791,8 @@ static int rk808_remove(struct i2c_client *client)
 	if (pm_power_off == rk808_pm_power_off)
 		pm_power_off = NULL;
 
+	unregister_restart_handler(&rk808_restart_handler);
+
 	return 0;
 }
 
diff --git a/include/linux/mfd/rk808.h b/include/linux/mfd/rk808.h
index a96e6d43ca06..58602032e642 100644
--- a/include/linux/mfd/rk808.h
+++ b/include/linux/mfd/rk808.h
@@ -373,6 +373,7 @@ enum rk805_reg {
 #define SWITCH2_EN	BIT(6)
 #define SWITCH1_EN	BIT(5)
 #define DEV_OFF_RST	BIT(3)
+#define DEV_RST		BIT(2)
 #define DEV_OFF		BIT(0)
 #define RTC_STOP	BIT(0)
 
-- 
2.25.1