thermal: Add QPNP PMIC temperature alarm driver

Add support for the temperature alarm peripheral found inside
Qualcomm plug-and-play (QPNP) PMIC chips. The temperature alarm
peripheral outputs a pulse on an interrupt line whenever the
thermal over temperature stage value changes.

Register a thermal sensor. The temperature reported by this thermal
sensor device should reflect the actual PMIC die temperature if an
ADC is present on the given PMIC. If no ADC is present, then the
reported temperature should be estimated from the over temperature
stage value.

Cc: David Collins <collinsd@codeaurora.org>
Signed-off-by: Ivan T. Ivanov <iivanov@mm-sol.com>
Signed-off-by: Eduardo Valentin <edubezval@gmail.com>

drivers/thermal/Kconfig

@@ -299,4 +299,15 @@ depends on ARCH_STI && OF
 source "drivers/thermal/st/Kconfig"
 endmenu
 
+config QCOM_SPMI_TEMP_ALARM
+	tristate "Qualcomm SPMI PMIC Temperature Alarm"
+	depends on OF && SPMI && IIO
+	select REGMAP_SPMI
+	help
+	  This enables a thermal sysfs driver for Qualcomm plug-and-play (QPNP)
+	  PMIC devices. It shows up in sysfs as a thermal sensor with multiple
+	  trip points. The temperature reported by the thermal sensor reflects the
+	  real time die temperature if an ADC is present or an estimate of the
+	  temperature based upon the over temperature stage value.
+
 endif