[PATCH 3/4] mfd: max77620: override PSCI poweroff handler on Pixel C

[Diogo Ivo]

On Pixel C, shutdown must be handled by the MAX77620 PMIC rather
than the PSCI SYSTEM_OFF call, whose firmware implementation is:

__dead2 void tegra_system_off(void)
{
        ERROR("Tegra System Off: operation not handled.\n");
        panic();
}

Raise the MAX77620 sys-off handler priority above SYS_OFF_PRIO_FIRMWARE
on Pixel C systems so it takes precedence over the PSCI poweroff handler.

Other systems continue to use the default sys-off priority.

Signed-off-by: Diogo Ivo <diogo.ivo at tecnico.ulisboa.pt>
---
 drivers/mfd/max77620.c | 18 ++++++++++++++++--
 1 file changed, 16 insertions(+), 2 deletions(-)

diff --git a/drivers/mfd/max77620.c b/drivers/mfd/max77620.c
index c4f89a9681f3..3b1f3a2f3566 100644
--- a/drivers/mfd/max77620.c
+++ b/drivers/mfd/max77620.c
@@ -494,6 +494,18 @@ static int max77620_pm_power_off(struct sys_off_data *data)
 	return NOTIFY_DONE;
 }
 
+static int max77620_power_off_priority(void)
+{
+	/*
+	 * For Smaug  we need to override the PSCI poweroff handler
+	 * which is registered at priority SYS_OFF_PRIO_FIRMWARE.
+	 */
+	if (of_machine_is_compatible("google,smaug"))
+		return SYS_OFF_PRIO_FIRMWARE + 1;
+
+	return SYS_OFF_PRIO_DEFAULT;
+}
+
 static int max77620_probe(struct i2c_client *client)
 {
 	const struct i2c_device_id *id = i2c_client_get_device_id(client);
@@ -502,6 +514,7 @@ static int max77620_probe(struct i2c_client *client)
 	struct regmap_irq_chip *chip_desc;
 	const struct mfd_cell *mfd_cells;
 	int n_mfd_cells;
+	int priority;
 	int ret;
 
 	chip = devm_kzalloc(&client->dev, sizeof(*chip), GFP_KERNEL);
@@ -574,10 +587,11 @@ static int max77620_probe(struct i2c_client *client)
 	}
 
 	if (of_device_is_system_power_controller(client->dev.of_node)) {
+		priority = max77620_power_off_priority();
 		ret = devm_register_sys_off_handler(&client->dev,
 						    SYS_OFF_MODE_POWER_OFF,
-						    SYS_OFF_PRIO_DEFAULT,
-						    max77620_pm_power_off, chip);
+						    priority, max77620_pm_power_off,
+						    chip);
 		if (ret)
 			return dev_err_probe(&client->dev, ret,
 					"failed to register power-off handler\n");

-- 
2.54.0