hwmon: (jc42) optionally try to disable the SMBUS timeout

[android-x86/kernel.git] / drivers / hwmon / jc42.c

diff --git a/drivers/hwmon/jc42.c b/drivers/hwmon/jc42.c
index 1bf22ef..0f1f642 100644 (file)
--- a/drivers/hwmon/jc42.c
+++ b/drivers/hwmon/jc42.c
@@ -22,6 +22,7 @@
  * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
  */
 
+#include <linux/bitops.h>
 #include <linux/module.h>
 #include <linux/init.h>
 #include <linux/slab.h>
@@ -45,6 +46,7 @@ static const unsigned short normal_i2c[] = {
 #define JC42_REG_TEMP          0x05
 #define JC42_REG_MANID         0x06
 #define JC42_REG_DEVICEID      0x07
+#define JC42_REG_SMBUS         0x22 /* NXP and Atmel, possibly others? */
 
 /* Status bits in temperature register */
 #define JC42_ALARM_CRIT_BIT    15
@@ -73,6 +75,9 @@ static const unsigned short normal_i2c[] = {
 #define ONS_MANID              0x1b09  /* ON Semiconductor */
 #define STM_MANID              0x104a  /* ST Microelectronics */
 
+/* SMBUS register */
+#define SMBUS_STMOUT           BIT(7)  /* SMBus time-out, active low */
+
 /* Supported chips */
 
 /* Analog Devices */
@@ -476,6 +481,22 @@ static int jc42_probe(struct i2c_client *client, const struct i2c_device_id *id)
 
        data->extended = !!(cap & JC42_CAP_RANGE);
 
+       if (device_property_read_bool(dev, "smbus-timeout-disable")) {
+               int smbus;
+
+               /*
+                * Not all chips support this register, but from a
+                * quick read of various datasheets no chip appears
+                * incompatible with the below attempt to disable
+                * the timeout. And the whole thing is opt-in...
+                */
+               smbus = i2c_smbus_read_word_swapped(client, JC42_REG_SMBUS);
+               if (smbus < 0)
+                       return smbus;
+               i2c_smbus_write_word_swapped(client, JC42_REG_SMBUS,
+                                            smbus | SMBUS_STMOUT);
+       }
+
        config = i2c_smbus_read_word_swapped(client, JC42_REG_CONFIG);
        if (config < 0)
                return config;