[PATCH v5 2/2] thermal: imx8mm: Allow reboot after critical temperature

[Fabio Estevam <festevam@gmail.com>]

From: Fabio Estevam <festevam@denx.de>

Currently, after the SoC reaches the critical temperature, the board
goes through a poweroff mechanism.

In some cases, such behavior does not suit well, as the board may be
unattended in the field and rebooting may be a better approach.

The bootloader may also check the temperature and only allow the boot to
proceed when the temperature is below a certain threshold.

Introduce the 'nxp,reboot-on-critical' property to indicate that the
board will go through a reboot after the critical temperature is reached.

When this property is absent, the default behavior of forcing a shutdown
is kept.

Tested on a imx8mm-evk board.

Signed-off-by: Fabio Estevam <festevam@denx.de>
---
Changes since v4:
- Went back to the devicetree approach.
- Populate tmu_tz_ops.critical inside probe (Daniel).
Changes since v3:
- Switch to sysfs.
Changes since v2:
- Populate tmu_tz_ops.critical inside probe (Daniel).
Changes since v1:
- Use module_param().

 drivers/thermal/imx8mm_thermal.c | 13 ++++++++++++-
 1 file changed, 12 insertions(+), 1 deletion(-)

diff --git a/drivers/thermal/imx8mm_thermal.c b/drivers/thermal/imx8mm_thermal.c
index e89b11b3f2b9..0ca3cba33f39 100644
--- a/drivers/thermal/imx8mm_thermal.c
+++ b/drivers/thermal/imx8mm_thermal.c
@@ -13,6 +13,7 @@
 #include <linux/nvmem-consumer.h>
 #include <linux/of.h>
 #include <linux/platform_device.h>
+#include <linux/reboot.h>
 #include <linux/slab.h>
 #include <linux/thermal.h>
 
@@ -146,7 +147,7 @@ static int tmu_get_temp(struct thermal_zone_device *tz, int *temp)
 	return tmu->socdata->get_temp(sensor, temp);
 }
 
-static const struct thermal_zone_device_ops tmu_tz_ops = {
+static struct thermal_zone_device_ops tmu_tz_ops = {
 	.get_temp = tmu_get_temp,
 };
 
@@ -293,6 +294,13 @@ static int imx8mm_tmu_probe_set_calib(struct platform_device *pdev,
 	return imx8mm_tmu_probe_set_calib_v2(pdev, tmu);
 }
 
+static void tmu_critical(struct thermal_zone_device *tz)
+{
+	dev_emerg(thermal_zone_device(tz), "%s: critical temperature reached\n",
+		  thermal_zone_device_type(tz));
+	kernel_restart(NULL);
+}
+
 static int imx8mm_tmu_probe(struct platform_device *pdev)
 {
 	const struct thermal_soc_data *data;
@@ -313,6 +321,9 @@ static int imx8mm_tmu_probe(struct platform_device *pdev)
 	if (IS_ERR(tmu->base))
 		return PTR_ERR(tmu->base);
 
+	if (of_property_present(pdev->dev.of_node, "nxp,reboot-on-critical"))
+		tmu_tz_ops.critical = tmu_critical;
+
 	tmu->clk = devm_clk_get(&pdev->dev, NULL);
 	if (IS_ERR(tmu->clk))
 		return dev_err_probe(&pdev->dev, PTR_ERR(tmu->clk),
-- 
2.34.1