1 files changed, 645 insertions, 0 deletions

diff --git a/drivers/sbus/char/bbc_envctrl.c b/drivers/sbus/char/bbc_envctrl.c
new file mode 100644
index 000000000000..d5259f7fee6d
--- /dev/null
+++ b/drivers/sbus/char/bbc_envctrl.c
@@ -0,0 +1,645 @@
+/* $Id: bbc_envctrl.c,v 1.4 2001/04/06 16:48:08 davem Exp $
+ * bbc_envctrl.c: UltraSPARC-III environment control driver.
+ *
+ * Copyright (C) 2001 David S. Miller (davem@redhat.com)
+ */
+
+#include <linux/kernel.h>
+#include <linux/sched.h>
+#include <linux/slab.h>
+#include <linux/delay.h>
+#include <asm/oplib.h>
+#include <asm/ebus.h>
+#define __KERNEL_SYSCALLS__
+static int errno;
+#include <asm/unistd.h>
+
+#include "bbc_i2c.h"
+#include "max1617.h"
+
+#undef ENVCTRL_TRACE
+
+/* WARNING: Making changes to this driver is very dangerous.
+ *          If you misprogram the sensor chips they can
+ *          cut the power on you instantly.
+ */
+
+/* Two temperature sensors exist in the SunBLADE-1000 enclosure.
+ * Both are implemented using max1617 i2c devices.  Each max1617
+ * monitors 2 temperatures, one for one of the cpu dies and the other
+ * for the ambient temperature.
+ *
+ * The max1617 is capable of being programmed with power-off
+ * temperature values, one low limit and one high limit.  These
+ * can be controlled independently for the cpu or ambient temperature.
+ * If a limit is violated, the power is simply shut off.  The frequency
+ * with which the max1617 does temperature sampling can be controlled
+ * as well.
+ *
+ * Three fans exist inside the machine, all three are controlled with
+ * an i2c digital to analog converter.  There is a fan directed at the
+ * two processor slots, another for the rest of the enclosure, and the
+ * third is for the power supply.  The first two fans may be speed
+ * controlled by changing the voltage fed to them.  The third fan may
+ * only be completely off or on.  The third fan is meant to only be
+ * disabled/enabled when entering/exiting the lowest power-saving
+ * mode of the machine.
+ *
+ * An environmental control kernel thread periodically monitors all
+ * temperature sensors.  Based upon the samples it will adjust the
+ * fan speeds to try and keep the system within a certain temperature
+ * range (the goal being to make the fans as quiet as possible without
+ * allowing the system to get too hot).
+ *
+ * If the temperature begins to rise/fall outside of the acceptable
+ * operating range, a periodic warning will be sent to the kernel log.
+ * The fans will be put on full blast to attempt to deal with this
+ * situation.  After exceeding the acceptable operating range by a
+ * certain threshold, the kernel thread will shut down the system.
+ * Here, the thread is attempting to shut the machine down cleanly
+ * before the hardware based power-off event is triggered.
+ */
+
+/* These settings are in Celsius.  We use these defaults only
+ * if we cannot interrogate the cpu-fru SEEPROM.
+ */
+struct temp_limits {
+        s8 high_pwroff, high_shutdown, high_warn;
+        s8 low_warn, low_shutdown, low_pwroff;
+};
+
+static struct temp_limits cpu_temp_limits[2] = {
+        { 100, 85, 80, 5, -5, -10 },
+        { 100, 85, 80, 5, -5, -10 },
+};
+
+static struct temp_limits amb_temp_limits[2] = {
+        { 65, 55, 40, 5, -5, -10 },
+        { 65, 55, 40, 5, -5, -10 },
+};
+
+enum fan_action { FAN_SLOWER, FAN_SAME, FAN_FASTER, FAN_FULLBLAST, FAN_STATE_MAX };
+
+struct bbc_cpu_temperature {
+        struct bbc_cpu_temperature      *next;
+
+        struct bbc_i2c_client           *client;
+        int                             index;
+
+        /* Current readings, and history. */
+        s8                              curr_cpu_temp;
+        s8                              curr_amb_temp;
+        s8                              prev_cpu_temp;
+        s8                              prev_amb_temp;
+        s8                              avg_cpu_temp;
+        s8                              avg_amb_temp;
+
+        int                             sample_tick;
+
+        enum fan_action                 fan_todo[2];
+#define FAN_AMBIENT     0
+#define FAN_CPU         1
+};
+
+struct bbc_cpu_temperature *all_bbc_temps;
+
+struct bbc_fan_control {
+        struct bbc_fan_control  *next;
+
+        struct bbc_i2c_client   *client;
+        int                     index;
+
+        int                     psupply_fan_on;
+        int                     cpu_fan_speed;
+        int                     system_fan_speed;
+};
+
+struct bbc_fan_control *all_bbc_fans;
+
+#define CPU_FAN_REG     0xf0
+#define SYS_FAN_REG     0xf2
+#define PSUPPLY_FAN_REG 0xf4
+
+#define FAN_SPEED_MIN   0x0c
+#define FAN_SPEED_MAX   0x3f
+
+#define PSUPPLY_FAN_ON  0x1f
+#define PSUPPLY_FAN_OFF 0x00
+
+static void set_fan_speeds(struct bbc_fan_control *fp)
+{
+        /* Put temperatures into range so we don't mis-program
+         * the hardware.
+         */
+        if (fp->cpu_fan_speed < FAN_SPEED_MIN)
+                fp->cpu_fan_speed = FAN_SPEED_MIN;
+        if (fp->cpu_fan_speed > FAN_SPEED_MAX)
+                fp->cpu_fan_speed = FAN_SPEED_MAX;
+        if (fp->system_fan_speed < FAN_SPEED_MIN)
+                fp->system_fan_speed = FAN_SPEED_MIN;
+        if (fp->system_fan_speed > FAN_SPEED_MAX)
+                fp->system_fan_speed = FAN_SPEED_MAX;
+#ifdef ENVCTRL_TRACE
+        printk("fan%d: Changed fan speed to cpu(%02x) sys(%02x)\n",
+               fp->index,
+               fp->cpu_fan_speed, fp->system_fan_speed);
+#endif
+
+        bbc_i2c_writeb(fp->client, fp->cpu_fan_speed, CPU_FAN_REG);
+        bbc_i2c_writeb(fp->client, fp->system_fan_speed, SYS_FAN_REG);
+        bbc_i2c_writeb(fp->client,
+                       (fp->psupply_fan_on ?
+                        PSUPPLY_FAN_ON : PSUPPLY_FAN_OFF),
+                       PSUPPLY_FAN_REG);
+}
+
+static void get_current_temps(struct bbc_cpu_temperature *tp)
+{
+        tp->prev_amb_temp = tp->curr_amb_temp;
+        bbc_i2c_readb(tp->client,
+                      (unsigned char *) &tp->curr_amb_temp,
+                      MAX1617_AMB_TEMP);
+        tp->prev_cpu_temp = tp->curr_cpu_temp;
+        bbc_i2c_readb(tp->client,
+                      (unsigned char *) &tp->curr_cpu_temp,
+                      MAX1617_CPU_TEMP);
+#ifdef ENVCTRL_TRACE
+        printk("temp%d: cpu(%d C) amb(%d C)\n",
+               tp->index,
+               (int) tp->curr_cpu_temp, (int) tp->curr_amb_temp);
+#endif
+}
+
+
+static void do_envctrl_shutdown(struct bbc_cpu_temperature *tp)
+{
+        static int shutting_down = 0;
+        static char *envp[] = { "HOME=/", "TERM=linux", "PATH=/sbin:/usr/sbin:/bin:/usr/bin", NULL };
+        char *argv[] = { "/sbin/shutdown", "-h", "now", NULL };
+        char *type = "???";
+        s8 val = -1;
+
+        if (shutting_down != 0)
+                return;
+
+        if (tp->curr_amb_temp >= amb_temp_limits[tp->index].high_shutdown ||
+            tp->curr_amb_temp < amb_temp_limits[tp->index].low_shutdown) {
+                type = "ambient";
+                val = tp->curr_amb_temp;
+        } else if (tp->curr_cpu_temp >= cpu_temp_limits[tp->index].high_shutdown ||
+                   tp->curr_cpu_temp < cpu_temp_limits[tp->index].low_shutdown) {
+                type = "CPU";
+                val = tp->curr_cpu_temp;
+        }
+
+        printk(KERN_CRIT "temp%d: Outside of safe %s "
+               "operating temperature, %d C.\n",
+               tp->index, type, val);
+
+        printk(KERN_CRIT "kenvctrld: Shutting down the system now.\n");
+
+        shutting_down = 1;
+        if (execve("/sbin/shutdown", argv, envp) < 0)
+                printk(KERN_CRIT "envctrl: shutdown execution failed\n");
+}
+
+#define WARN_INTERVAL   (30 * HZ)
+
+static void analyze_ambient_temp(struct bbc_cpu_temperature *tp, unsigned long *last_warn, int tick)
+{
+        int ret = 0;
+
+        if (time_after(jiffies, (*last_warn + WARN_INTERVAL))) {
+                if (tp->curr_amb_temp >=
+                    amb_temp_limits[tp->index].high_warn) {
+                        printk(KERN_WARNING "temp%d: "
+                               "Above safe ambient operating temperature, %d C.\n",
+                               tp->index, (int) tp->curr_amb_temp);
+                        ret = 1;
+                } else if (tp->curr_amb_temp <
+                           amb_temp_limits[tp->index].low_warn) {
+                        printk(KERN_WARNING "temp%d: "
+                               "Below safe ambient operating temperature, %d C.\n",
+                               tp->index, (int) tp->curr_amb_temp);
+                        ret = 1;
+                }
+                if (ret)
+                        *last_warn = jiffies;
+        } else if (tp->curr_amb_temp >= amb_temp_limits[tp->index].high_warn ||
+                   tp->curr_amb_temp < amb_temp_limits[tp->index].low_warn)
+                ret = 1;
+
+        /* Now check the shutdown limits. */
+        if (tp->curr_amb_temp >= amb_temp_limits[tp->index].high_shutdown ||
+            tp->curr_amb_temp < amb_temp_limits[tp->index].low_shutdown) {
+                do_envctrl_shutdown(tp);
+                ret = 1;
+        }
+
+        if (ret) {
+                tp->fan_todo[FAN_AMBIENT] = FAN_FULLBLAST;
+        } else if ((tick & (8 - 1)) == 0) {
+                s8 amb_goal_hi = amb_temp_limits[tp->index].high_warn - 10;
+                s8 amb_goal_lo;
+
+                amb_goal_lo = amb_goal_hi - 3;
+
+                /* We do not try to avoid 'too cold' events.  Basically we
+                 * only try to deal with over-heating and fan noise reduction.
+                 */
+                if (tp->avg_amb_temp < amb_goal_hi) {
+                        if (tp->avg_amb_temp >= amb_goal_lo)
+                                tp->fan_todo[FAN_AMBIENT] = FAN_SAME;
+                        else
+                                tp->fan_todo[FAN_AMBIENT] = FAN_SLOWER;
+                } else {
+                        tp->fan_todo[FAN_AMBIENT] = FAN_FASTER;
+                }
+        } else {
+                tp->fan_todo[FAN_AMBIENT] = FAN_SAME;
+        }
+}
+
+static void analyze_cpu_temp(struct bbc_cpu_temperature *tp, unsigned long *last_warn, int tick)
+{
+        int ret = 0;
+
+        if (time_after(jiffies, (*last_warn + WARN_INTERVAL))) {
+                if (tp->curr_cpu_temp >=
+                    cpu_temp_limits[tp->index].high_warn) {
+                        printk(KERN_WARNING "temp%d: "
+                               "Above safe CPU operating temperature, %d C.\n",
+                               tp->index, (int) tp->curr_cpu_temp);
+                        ret = 1;
+                } else if (tp->curr_cpu_temp <
+                           cpu_temp_limits[tp->index].low_warn) {
+                        printk(KERN_WARNING "temp%d: "
+                               "Below safe CPU operating temperature, %d C.\n",
+                               tp->index, (int) tp->curr_cpu_temp);
+                        ret = 1;
+                }
+                if (ret)
+                        *last_warn = jiffies;
+        } else if (tp->curr_cpu_temp >= cpu_temp_limits[tp->index].high_warn ||
+                   tp->curr_cpu_temp < cpu_temp_limits[tp->index].low_warn)
+                ret = 1;
+
+        /* Now check the shutdown limits. */
+        if (tp->curr_cpu_temp >= cpu_temp_limits[tp->index].high_shutdown ||
+            tp->curr_cpu_temp < cpu_temp_limits[tp->index].low_shutdown) {
+                do_envctrl_shutdown(tp);
+                ret = 1;
+        }
+
+        if (ret) {
+                tp->fan_todo[FAN_CPU] = FAN_FULLBLAST;
+        } else if ((tick & (8 - 1)) == 0) {
+                s8 cpu_goal_hi = cpu_temp_limits[tp->index].high_warn - 10;
+                s8 cpu_goal_lo;
+
+                cpu_goal_lo = cpu_goal_hi - 3;
+
+                /* We do not try to avoid 'too cold' events.  Basically we
+                 * only try to deal with over-heating and fan noise reduction.
+                 */
+                if (tp->avg_cpu_temp < cpu_goal_hi) {
+                        if (tp->avg_cpu_temp >= cpu_goal_lo)
+                                tp->fan_todo[FAN_CPU] = FAN_SAME;
+                        else
+                                tp->fan_todo[FAN_CPU] = FAN_SLOWER;
+                } else {
+                        tp->fan_todo[FAN_CPU] = FAN_FASTER;
+                }
+        } else {
+                tp->fan_todo[FAN_CPU] = FAN_SAME;
+        }
+}
+
+static void analyze_temps(struct bbc_cpu_temperature *tp, unsigned long *last_warn)
+{
+        tp->avg_amb_temp = (s8)((int)((int)tp->avg_amb_temp + (int)tp->curr_amb_temp) / 2);
+        tp->avg_cpu_temp = (s8)((int)((int)tp->avg_cpu_temp + (int)tp->curr_cpu_temp) / 2);
+
+        analyze_ambient_temp(tp, last_warn, tp->sample_tick);
+        analyze_cpu_temp(tp, last_warn, tp->sample_tick);
+
+        tp->sample_tick++;
+}
+
+static enum fan_action prioritize_fan_action(int which_fan)
+{
+        struct bbc_cpu_temperature *tp;
+        enum fan_action decision = FAN_STATE_MAX;
+
+        /* Basically, prioritize what the temperature sensors
+         * recommend we do, and perform that action on all the
+         * fans.
+         */
+        for (tp = all_bbc_temps; tp; tp = tp->next) {
+                if (tp->fan_todo[which_fan] == FAN_FULLBLAST) {
+                        decision = FAN_FULLBLAST;
+                        break;
+                }
+                if (tp->fan_todo[which_fan] == FAN_SAME &&
+                    decision != FAN_FASTER)
+                        decision = FAN_SAME;
+                else if (tp->fan_todo[which_fan] == FAN_FASTER)
+                        decision = FAN_FASTER;
+                else if (decision != FAN_FASTER &&
+                         decision != FAN_SAME &&
+                         tp->fan_todo[which_fan] == FAN_SLOWER)
+                        decision = FAN_SLOWER;
+        }
+        if (decision == FAN_STATE_MAX)
+                decision = FAN_SAME;
+
+        return decision;
+}
+
+static int maybe_new_ambient_fan_speed(struct bbc_fan_control *fp)
+{
+        enum fan_action decision = prioritize_fan_action(FAN_AMBIENT);
+        int ret;
+
+        if (decision == FAN_SAME)
+                return 0;
+
+        ret = 1;
+        if (decision == FAN_FULLBLAST) {
+                if (fp->system_fan_speed >= FAN_SPEED_MAX)
+                        ret = 0;
+                else
+                        fp->system_fan_speed = FAN_SPEED_MAX;
+        } else {
+                if (decision == FAN_FASTER) {
+                        if (fp->system_fan_speed >= FAN_SPEED_MAX)
+                                ret = 0;
+                        else
+                                fp->system_fan_speed += 2;
+                } else {
+                        int orig_speed = fp->system_fan_speed;
+
+                        if (orig_speed <= FAN_SPEED_MIN ||
+                            orig_speed <= (fp->cpu_fan_speed - 3))
+                                ret = 0;
+                        else
+                                fp->system_fan_speed -= 1;
+                }
+        }
+
+        return ret;
+}
+
+static int maybe_new_cpu_fan_speed(struct bbc_fan_control *fp)
+{
+        enum fan_action decision = prioritize_fan_action(FAN_CPU);
+        int ret;
+
+        if (decision == FAN_SAME)
+                return 0;
+
+        ret = 1;
+        if (decision == FAN_FULLBLAST) {
+                if (fp->cpu_fan_speed >= FAN_SPEED_MAX)
+                        ret = 0;
+                else
+                        fp->cpu_fan_speed = FAN_SPEED_MAX;
+        } else {
+                if (decision == FAN_FASTER) {
+                        if (fp->cpu_fan_speed >= FAN_SPEED_MAX)
+                                ret = 0;
+                        else {
+                                fp->cpu_fan_speed += 2;
+                                if (fp->system_fan_speed <
+                                    (fp->cpu_fan_speed - 3))
+                                        fp->system_fan_speed =
+                                                fp->cpu_fan_speed - 3;
+                        }
+                } else {
+                        if (fp->cpu_fan_speed <= FAN_SPEED_MIN)
+                                ret = 0;
+                        else
+                                fp->cpu_fan_speed -= 1;
+                }
+        }
+
+        return ret;
+}
+
+static void maybe_new_fan_speeds(struct bbc_fan_control *fp)
+{
+        int new;
+
+        new  = maybe_new_ambient_fan_speed(fp);
+        new |= maybe_new_cpu_fan_speed(fp);
+
+        if (new)
+                set_fan_speeds(fp);
+}
+
+static void fans_full_blast(void)
+{
+        struct bbc_fan_control *fp;
+
+        /* Since we will not be monitoring things anymore, put
+         * the fans on full blast.
+         */
+        for (fp = all_bbc_fans; fp; fp = fp->next) {
+                fp->cpu_fan_speed = FAN_SPEED_MAX;
+                fp->system_fan_speed = FAN_SPEED_MAX;
+                fp->psupply_fan_on = 1;
+                set_fan_speeds(fp);
+        }
+}
+
+#define POLL_INTERVAL   (5 * 1000)
+static unsigned long last_warning_jiffies;
+static struct task_struct *kenvctrld_task;
+
+static int kenvctrld(void *__unused)
+{
+        daemonize("kenvctrld");
+        allow_signal(SIGKILL);
+        kenvctrld_task = current;
+
+        printk(KERN_INFO "bbc_envctrl: kenvctrld starting...\n");
+        last_warning_jiffies = jiffies - WARN_INTERVAL;
+        for (;;) {
+                struct bbc_cpu_temperature *tp;
+                struct bbc_fan_control *fp;
+
+                msleep_interruptible(POLL_INTERVAL);
+                if (signal_pending(current))
+                        break;
+
+                for (tp = all_bbc_temps; tp; tp = tp->next) {
+                        get_current_temps(tp);
+                        analyze_temps(tp, &last_warning_jiffies);
+                }
+                for (fp = all_bbc_fans; fp; fp = fp->next)
+                        maybe_new_fan_speeds(fp);
+        }
+        printk(KERN_INFO "bbc_envctrl: kenvctrld exiting...\n");
+
+        fans_full_blast();
+
+        return 0;
+}
+
+static void attach_one_temp(struct linux_ebus_child *echild, int temp_idx)
+{
+        struct bbc_cpu_temperature *tp = kmalloc(sizeof(*tp), GFP_KERNEL);
+
+        if (!tp)
+                return;
+        memset(tp, 0, sizeof(*tp));
+        tp->client = bbc_i2c_attach(echild);
+        if (!tp->client) {
+                kfree(tp);
+                return;
+        }
+
+        tp->index = temp_idx;
+        {
+                struct bbc_cpu_temperature **tpp = &all_bbc_temps;
+                while (*tpp)
+                        tpp = &((*tpp)->next);
+                tp->next = NULL;
+                *tpp = tp;
+        }
+
+        /* Tell it to convert once every 5 seconds, clear all cfg
+         * bits.
+         */
+        bbc_i2c_writeb(tp->client, 0x00, MAX1617_WR_CFG_BYTE);
+        bbc_i2c_writeb(tp->client, 0x02, MAX1617_WR_CVRATE_BYTE);
+
+        /* Program the hard temperature limits into the chip. */
+        bbc_i2c_writeb(tp->client, amb_temp_limits[tp->index].high_pwroff,
+                       MAX1617_WR_AMB_HIGHLIM);
+        bbc_i2c_writeb(tp->client, amb_temp_limits[tp->index].low_pwroff,
+                       MAX1617_WR_AMB_LOWLIM);
+        bbc_i2c_writeb(tp->client, cpu_temp_limits[tp->index].high_pwroff,
+                       MAX1617_WR_CPU_HIGHLIM);
+        bbc_i2c_writeb(tp->client, cpu_temp_limits[tp->index].low_pwroff,
+                       MAX1617_WR_CPU_LOWLIM);
+
+        get_current_temps(tp);
+        tp->prev_cpu_temp = tp->avg_cpu_temp = tp->curr_cpu_temp;
+        tp->prev_amb_temp = tp->avg_amb_temp = tp->curr_amb_temp;
+
+        tp->fan_todo[FAN_AMBIENT] = FAN_SAME;
+        tp->fan_todo[FAN_CPU] = FAN_SAME;
+}
+
+static void attach_one_fan(struct linux_ebus_child *echild, int fan_idx)
+{
+        struct bbc_fan_control *fp = kmalloc(sizeof(*fp), GFP_KERNEL);
+
+        if (!fp)
+                return;
+        memset(fp, 0, sizeof(*fp));
+        fp->client = bbc_i2c_attach(echild);
+        if (!fp->client) {
+                kfree(fp);
+                return;
+        }
+
+        fp->index = fan_idx;
+
+        {
+                struct bbc_fan_control **fpp = &all_bbc_fans;
+                while (*fpp)
+                        fpp = &((*fpp)->next);
+                fp->next = NULL;
+                *fpp = fp;
+        }
+
+        /* The i2c device controlling the fans is write-only.
+         * So the only way to keep track of the current power
+         * level fed to the fans is via software.  Choose half
+         * power for cpu/system and 'on' fo the powersupply fan
+         * and set it now.
+         */
+        fp->psupply_fan_on = 1;
+        fp->cpu_fan_speed = (FAN_SPEED_MAX - FAN_SPEED_MIN) / 2;
+        fp->cpu_fan_speed += FAN_SPEED_MIN;
+        fp->system_fan_speed = (FAN_SPEED_MAX - FAN_SPEED_MIN) / 2;
+        fp->system_fan_speed += FAN_SPEED_MIN;
+
+        set_fan_speeds(fp);
+}
+
+int bbc_envctrl_init(void)
+{
+        struct linux_ebus_child *echild;
+        int temp_index = 0;
+        int fan_index = 0;
+        int devidx = 0;
+        int err = 0;
+
+        while ((echild = bbc_i2c_getdev(devidx++)) != NULL) {
+                if (!strcmp(echild->prom_name, "temperature"))
+                        attach_one_temp(echild, temp_index++);
+                if (!strcmp(echild->prom_name, "fan-control"))
+                        attach_one_fan(echild, fan_index++);
+        }
+        if (temp_index != 0 && fan_index != 0)
+                err = kernel_thread(kenvctrld, NULL, CLONE_FS | CLONE_FILES);
+        return err;
+}
+
+static void destroy_one_temp(struct bbc_cpu_temperature *tp)
+{
+        bbc_i2c_detach(tp->client);
+        kfree(tp);
+}
+
+static void destroy_one_fan(struct bbc_fan_control *fp)
+{
+        bbc_i2c_detach(fp->client);
+        kfree(fp);
+}
+
+void bbc_envctrl_cleanup(void)
+{
+        struct bbc_cpu_temperature *tp;
+        struct bbc_fan_control *fp;
+
+        if (kenvctrld_task != NULL) {
+                force_sig(SIGKILL, kenvctrld_task);
+                for (;;) {
+                        struct task_struct *p;
+                        int found = 0;
+
+                        read_lock(&tasklist_lock);
+                        for_each_process(p) {
+                                if (p == kenvctrld_task) {
+                                        found = 1;
+                                        break;
+                                }
+                        }
+                        read_unlock(&tasklist_lock);
+                        if (!found)
+                                break;
+                        msleep(1000);
+                }
+                kenvctrld_task = NULL;
+        }
+
+        tp = all_bbc_temps;
+        while (tp != NULL) {
+                struct bbc_cpu_temperature *next = tp->next;
+                destroy_one_temp(tp);
+                tp = next;
+        }
+        all_bbc_temps = NULL;
+
+        fp = all_bbc_fans;
+        while (fp != NULL) {
+                struct bbc_fan_control *next = fp->next;
+                destroy_one_fan(fp);
+                fp = next;
+        }
+        all_bbc_fans = NULL;
+}