hwmon: (it87) Prevent power-off on Shuttle SN68PT

On the Shuttle SN68PT, FAN_CTL2 is apparently not connected to a fan,
but to something else. One user has reported instant system power-off
when changing the PWM2 duty cycle, so we disable it.

I use the board name string as the trigger in case the same board is
ever used in other systems.

This closes lm-sensors ticket #2349:
pwmconfig causes a hard poweroff
http://www.lm-sensors.org/ticket/2349

Signed-off-by: Jean Delvare <khali@linux-fr.org>

1 files changed, 51 insertions, 19 deletions

diff --git a/drivers/hwmon/it87.c b/drivers/hwmon/it87.c
index f1133081cc4..d793cc01199 100644
--- a/drivers/hwmon/it87.c
+++ b/drivers/hwmon/it87.c
@@ -46,6 +46,8 @@
 #include <linux/err.h>
 #include <linux/mutex.h>
 #include <linux/sysfs.h>
+#include <linux/string.h>
+#include <linux/dmi.h>
 #include <asm/io.h>
 
 #define DRVNAME "it87"
@@ -236,6 +238,8 @@ struct it87_sio_data {
         /* Values read from Super-I/O config space */
         u8 revision;
         u8 vid_value;
+        /* Values set based on DMI strings */
+        u8 skip_pwm;
 };
 
 /* For each registered chip, we need to keep some data in memory.
@@ -964,6 +968,7 @@ static int __init it87_find(unsigned short *address,
 {
         int err = -ENODEV;
         u16 chip_type;
+        const char *board_vendor, *board_name;
 
         superio_enter();
         chip_type = force_id ? force_id : superio_inw(DEVID);
@@ -1022,6 +1027,24 @@ static int __init it87_find(unsigned short *address,
                         pr_info("it87: in7 is VCCH (+5V Stand-By)\n");
         }
 
+        /* Disable specific features based on DMI strings */
+        board_vendor = dmi_get_system_info(DMI_BOARD_VENDOR);
+        board_name = dmi_get_system_info(DMI_BOARD_NAME);
+        if (board_vendor && board_name) {
+                if (strcmp(board_vendor, "nVIDIA") == 0
+                 && strcmp(board_name, "FN68PT") == 0) {
+                        /* On the Shuttle SN68PT, FAN_CTL2 is apparently not
+                           connected to a fan, but to something else. One user
+                           has reported instant system power-off when changing
+                           the PWM2 duty cycle, so we disable it.
+                           I use the board name string as the trigger in case
+                           the same board is ever used in other systems. */
+                        pr_info("it87: Disabling pwm2 due to "
+                                "hardware constraints\n");
+                        sio_data->skip_pwm = (1 << 1);
+                }
+        }
+
 exit:
         superio_exit();
         return err;
@@ -1168,25 +1191,33 @@ static int __devinit it87_probe(struct platform_device *pdev)
         }
 
         if (enable_pwm_interface) {
-                if ((err = device_create_file(dev,
-                     &sensor_dev_attr_pwm1_enable.dev_attr))
-                 || (err = device_create_file(dev,
-                     &sensor_dev_attr_pwm2_enable.dev_attr))
-                 || (err = device_create_file(dev,
-                     &sensor_dev_attr_pwm3_enable.dev_attr))
-                 || (err = device_create_file(dev,
-                     &sensor_dev_attr_pwm1.dev_attr))
-                 || (err = device_create_file(dev,
-                     &sensor_dev_attr_pwm2.dev_attr))
-                 || (err = device_create_file(dev,
-                     &sensor_dev_attr_pwm3.dev_attr))
-                 || (err = device_create_file(dev,
-                     &dev_attr_pwm1_freq))
-                 || (err = device_create_file(dev,
-                     &dev_attr_pwm2_freq))
-                 || (err = device_create_file(dev,
-                     &dev_attr_pwm3_freq)))
-                        goto ERROR4;
+                if (!(sio_data->skip_pwm & (1 << 0))) {
+                        if ((err = device_create_file(dev,
+                             &sensor_dev_attr_pwm1_enable.dev_attr))
+                         || (err = device_create_file(dev,
+                             &sensor_dev_attr_pwm1.dev_attr))
+                         || (err = device_create_file(dev,
+                             &dev_attr_pwm1_freq)))
+                                goto ERROR4;
+                }
+                if (!(sio_data->skip_pwm & (1 << 1))) {
+                        if ((err = device_create_file(dev,
+                             &sensor_dev_attr_pwm2_enable.dev_attr))
+                         || (err = device_create_file(dev,
+                             &sensor_dev_attr_pwm2.dev_attr))
+                         || (err = device_create_file(dev,
+                             &dev_attr_pwm2_freq)))
+                                goto ERROR4;
+                }
+                if (!(sio_data->skip_pwm & (1 << 2))) {
+                        if ((err = device_create_file(dev,
+                             &sensor_dev_attr_pwm3_enable.dev_attr))
+                         || (err = device_create_file(dev,
+                             &sensor_dev_attr_pwm3.dev_attr))
+                         || (err = device_create_file(dev,
+                             &dev_attr_pwm3_freq)))
+                                goto ERROR4;
+                }
         }
 
         if (data->type == it8712 || data->type == it8716
@@ -1546,6 +1577,7 @@ static int __init sm_it87_init(void)
         unsigned short isa_address=0;
         struct it87_sio_data sio_data;
 
+        memset(&sio_data, 0, sizeof(struct it87_sio_data));
         err = it87_find(&isa_address, &sio_data);
         if (err)
                 return err;