---

yaml
---
r: 44973
b: refs/heads/master
c: 16663a8
h: refs/heads/master
i:
  44971: d8331a8
v: v3

[refs]

@@ -1,2 +1,2 @@
 ---
-refs/heads/master: 778b4d742b210b9cac31f223527f30f1fc70312b
+refs/heads/master: 16663a87ad1df7022661bc8813b7a2e84e7f5e66

trunk/Documentation/ibm-acpi.txt

@@ -670,6 +670,26 @@ example:
 
 	modprobe ibm_acpi hotkey=enable,0xffff video=auto_disable
 
+The ibm-acpi kernel driver can be programmed to revert the fan level
+to a safe setting if userspace does not issue one of the fan commands:
+"enable", "disable", "level" or "watchdog" within a configurable
+ammount of time.  To do this, use the "watchdog" command.
+
+	echo 'watchdog <interval>' > /proc/acpi/ibm/fan
+
+Interval is the ammount of time in seconds to wait for one of the
+above mentioned fan commands before reseting the fan level to a safe
+one.  If set to zero, the watchdog is disabled (default).  When the
+watchdog timer runs out, it does the exact equivalent of the "enable"
+fan command.
+
+Note that the watchdog timer stops after it enables the fan.  It will
+be rearmed again automatically (using the same interval) when one of
+the above mentioned fan commands is received.  The fan watchdog is,
+therefore, not suitable to protect against fan mode changes made
+through means other than the "enable", "disable", and "level" fan
+commands.
+
 
 Example Configuration
 ---------------------

trunk/drivers/acpi/ibm_acpi.c

@@ -82,6 +82,8 @@
 #include <linux/backlight.h>
 #include <asm/uaccess.h>
 #include <linux/dmi.h>
+#include <linux/jiffies.h>
+#include <linux/workqueue.h>
 
 #include <acpi/acpi_drivers.h>
 #include <acpi/acnamesp.h>
@@ -348,7 +350,8 @@ enum fan_control_access_mode {
 enum fan_control_commands {
 	IBMACPI_FAN_CMD_SPEED 	= 0x0001,	/* speed command */
 	IBMACPI_FAN_CMD_LEVEL 	= 0x0002,	/* level command  */
-	IBMACPI_FAN_CMD_ENABLE	= 0x0004,	/* enable/disable cmd */
+	IBMACPI_FAN_CMD_ENABLE	= 0x0004,	/* enable/disable cmd,
+						 * and also watchdog cmd */
 };
 
 enum {					/* Fan control constants */
@@ -1797,12 +1800,17 @@ static enum fan_control_commands fan_control_commands;
 static int fan_control_status_known;
 static u8 fan_control_initial_status;
 
+static void fan_watchdog_fire(void *ignored);
+static int fan_watchdog_maxinterval;
+static DECLARE_WORK(fan_watchdog_task, fan_watchdog_fire, NULL);
+
 static int fan_init(void)
 {
 	fan_status_access_mode = IBMACPI_FAN_NONE;
 	fan_control_access_mode = IBMACPI_FAN_WR_NONE;
 	fan_control_commands = 0;
 	fan_control_status_known = 1;
+	fan_watchdog_maxinterval = 0;
 
 	if (gfan_handle) {
 		/* 570, 600e/x, 770e, 770x */
@@ -1934,6 +1942,31 @@ static int fan_get_speed(unsigned int *speed)
 	return 0;
 }
 
+static void fan_exit(void)
+{
+	cancel_delayed_work(&fan_watchdog_task);
+	flush_scheduled_work();
+}
+
+static void fan_watchdog_reset(void)
+{
+	static int fan_watchdog_active = 0;
+
+	if (fan_watchdog_active)
+		cancel_delayed_work(&fan_watchdog_task);
+
+	if (fan_watchdog_maxinterval > 0) {
+		fan_watchdog_active = 1;
+		if (!schedule_delayed_work(&fan_watchdog_task,
+				msecs_to_jiffies(fan_watchdog_maxinterval
+						 * 1000))) {
+			printk(IBM_ERR "failed to schedule the fan watchdog, "
+			       "watchdog will not trigger\n");
+		}
+	} else
+		fan_watchdog_active = 0;
+}
+
 static int fan_read(char *p)
 {
 	int len = 0;
@@ -2007,7 +2040,9 @@ static int fan_read(char *p)
 	}
 
 	if (fan_control_commands & IBMACPI_FAN_CMD_ENABLE)
-		len += sprintf(p + len, "commands:\tenable, disable\n");
+		len += sprintf(p + len, "commands:\tenable, disable\n"
+			       "commands:\twatchdog <timeout> (<timeout> is 0 (off), "
+			       "1-120 (seconds))\n");
 
 	if (fan_control_commands & IBMACPI_FAN_CMD_SPEED)
 		len += sprintf(p + len, "commands:\tspeed <speed>"
@@ -2186,6 +2221,21 @@ static int fan_write_cmd_speed(const char *cmd, int *rc)
 	return 1;
 }
 
+static int fan_write_cmd_watchdog(const char *cmd, int *rc)
+{
+	int interval;
+
+	if (sscanf(cmd, "watchdog %d", &interval) != 1)
+		return 0;
+
+	if (interval < 0 || interval > 120)
+		*rc = -EINVAL;
+	else
+		fan_watchdog_maxinterval = interval;
+
+	return 1;
+}
+
 static int fan_write(char *buf)
 {
 	char *cmd;
@@ -2196,16 +2246,29 @@ static int fan_write(char *buf)
 		      fan_write_cmd_level(cmd, &rc)) &&
 		    !((fan_control_commands & IBMACPI_FAN_CMD_ENABLE) &&
 		      (fan_write_cmd_enable(cmd, &rc) ||
-		       fan_write_cmd_disable(cmd, &rc))) &&
+		       fan_write_cmd_disable(cmd, &rc) ||
+		       fan_write_cmd_watchdog(cmd, &rc))) &&
 		    !((fan_control_commands & IBMACPI_FAN_CMD_SPEED) &&
 		      fan_write_cmd_speed(cmd, &rc))
 		    )
 			rc = -EINVAL;
+		else if (!rc)
+			fan_watchdog_reset();
 	}
 
 	return rc;
 }
 
+static void fan_watchdog_fire(void *ignored)
+{
+	printk(IBM_NOTICE "fan watchdog: enabling fan\n");
+	if (fan_set_enable()) {
+		printk(IBM_ERR "fan watchdog: error while enabling fan\n");
+		/* reschedule for later */
+		fan_watchdog_reset();
+	}
+}
+
 static struct ibm_struct ibms[] = {
 	{
 	 .name = "driver",
@@ -2317,6 +2380,7 @@ static struct ibm_struct ibms[] = {
 	 .read = fan_read,
 	 .write = fan_write,
 	 .init = fan_init,
+	 .exit = fan_exit,
 	 .experimental = 1,
 	 },
 };