ACPI: thinkpad-acpi: add sysfs support to the thermal subdriver

Export thinkpad thermal sensors to sysfs, following the hwmon
specification for thermal monitoring sensors.

ThinkPad thermal monitoring is done by the EC.  Sensors can show up or
disappear at runtime when they are inside hotswappable hardware, such as
batteries.  Sensors that are not available return -ENXIO when accessed.

Up to 16 thermal sensors are supported on new firmware (but nobody has
reported a ThinkPad with more than 12 sensors so far), and 8 sensors are
supported on older firmware.  Thermal sensor mapping is model-specific.
Precision varies, it is 1 degree Celcius on new ThinkPads, but higher on
some older models.

Signed-off-by: Henrique de Moraes Holschuh <hmh@hmh.eng.br>
Signed-off-by: Len Brown <len.brown@intel.com>

1 files changed, 2 insertions, 0 deletions

diff --git a/drivers/misc/thinkpad_acpi.h b/drivers/misc/thinkpad_acpi.h
index a9feb53c6d3c..e833ff3caf39 100644
--- a/drivers/misc/thinkpad_acpi.h
+++ b/drivers/misc/thinkpad_acpi.h
@@ -38,6 +38,7 @@
 #include <linux/fb.h>
 #include <linux/platform_device.h>
 #include <linux/hwmon.h>
+#include <linux/hwmon-sysfs.h>
 #include <asm/uaccess.h>
 
 #include <linux/dmi.h>
@@ -467,6 +468,7 @@ enum thermal_access_mode {
 enum { /* TPACPI_THERMAL_TPEC_* */
         TP_EC_THERMAL_TMP0 = 0x78,      /* ACPI EC regs TMP 0..7 */
         TP_EC_THERMAL_TMP8 = 0xC0,      /* ACPI EC regs TMP 8..15 */
+        TP_EC_THERMAL_TMP_NA = -128,    /* ACPI EC sensor not available */
 };
 
 #define TPACPI_MAX_THERMAL_SENSORS 16   /* Max thermal sensors supported */