/* * bios-less APM driver for ARM Linux * Jamey Hicks * adapted from the APM BIOS driver for Linux by Stephen Rothwell (sfr@linuxcare.com) * * APM 1.2 Reference: * Intel Corporation, Microsoft Corporation. Advanced Power Management * (APM) BIOS Interface Specification, Revision 1.2, February 1996. * * [This document is available from Microsoft at: * http://www.microsoft.com/hwdev/busbios/amp_12.htm] */ #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include /* * The apm_bios device is one of the misc char devices. * This is its minor number. */ #define APM_MINOR_DEV 134 /* * See Documentation/Config.help for the configuration options. * * Various options can be changed at boot time as follows: * (We allow underscores for compatibility with the modules code) * apm=on/off enable/disable APM */ /* * Maximum number of events stored */ #define APM_MAX_EVENTS 16 struct apm_queue { unsigned int event_head; unsigned int event_tail; apm_event_t events[APM_MAX_EVENTS]; }; /* * The per-file APM data */ struct apm_user { struct list_head list; unsigned int suser: 1; unsigned int writer: 1; unsigned int reader: 1; int suspend_result; unsigned int suspend_state; #define SUSPEND_NONE 0 /* no suspend pending */ #define SUSPEND_PENDING 1 /* suspend pending read */ #define SUSPEND_READ 2 /* suspend read, pending ack */ #define SUSPEND_ACKED 3 /* suspend acked */ #define SUSPEND_WAIT 4 /* waiting for suspend */ #define SUSPEND_DONE 5 /* suspend completed */ struct apm_queue queue; }; /* * Local variables */ static int suspends_pending; static int apm_disabled; static struct task_struct *kapmd_tsk; static DECLARE_WAIT_QUEUE_HEAD(apm_waitqueue); static DECLARE_WAIT_QUEUE_HEAD(apm_suspend_waitqueue); /* * This is a list of everyone who has opened /dev/apm_bios */ static DECLARE_RWSEM(user_list_lock); static LIST_HEAD(apm_user_list); /* * kapmd info. kapmd provides us a process context to handle * "APM" events within - specifically necessary if we're going * to be suspending the system. */ static DECLARE_WAIT_QUEUE_HEAD(kapmd_wait); static DEFINE_SPINLOCK(kapmd_queue_lock); static struct apm_queue kapmd_queue; static DEFINE_MUTEX(state_lock); static const char driver_version[] = "1.13"; /* no spaces */ /* * Compatibility cruft until the IPAQ people move over to the new * interface. */ static void __apm_get_power_status(struct apm_power_info *info) { } /* * This allows machines to provide their own "apm get power status" function. */ void (*apm_get_power_status)(struct apm_power_info *) = __apm_get_power_status; EXPORT_SYMBOL(apm_get_power_status); /* * APM event queue management. */ static inline int queue_empty(struct apm_queue *q) { return q->event_head == q->event_tail; } static inline apm_event_t queue_get_event(struct apm_queue *q) { q->event_tail = (q->event_tail + 1) % APM_MAX_EVENTS; return q->events[q->event_tail]; } static void queue_add_event(struct apm_queue *q, apm_event_t event) { q->event_head = (q->event_head + 1) % APM_MAX_EVENTS; if (q->event_head == q->event_tail) { static int notified; if (notified++ == 0) printk(KERN_ERR "apm: an event queue overflowed\n"); q->event_tail = (q->event_tail + 1) % APM_MAX_EVENTS; } q->events[q->event_head] = event; } static void queue_event(apm_event_t event) { struct apm_user *as; down_read(&user_list_lock); list_for_each_entry(as, &apm_user_list, list) { if (as->reader) queue_add_event(&as->queue, event); } up_read(&user_list_lock); wake_up_interruptible(&apm_waitqueue); } /* * queue_suspend_event - queue an APM suspend event. * * Check that we're in a state where we can suspend. If not, * return -EBUSY. Otherwise, queue an event to all "writer" * users. If there are no "writer" users, return '1' to * indicate that we can immediately suspend. */ static int queue_suspend_event(apm_event_t event, struct apm_user *sender) { struct apm_user *as; int ret = 1; mutex_lock(&state_lock); down_read(&user_list_lock); /* * If a thread is still processing, we can't suspend, so reject * the request. */ list_for_each_entry(as, &apm_user_list, list) { if (as != sender && as->reader && as->writer && as->suser && as->suspend_state != SUSPEND_NONE) { ret = -EBUSY; goto out; } } list_for_each_entry(as, &apm_user_list, list) { if (as != sender && as->reader && as->writer && as->suser) { as->suspend_state = SUSPEND_PENDING; suspends_pending++; queue_add_event(&as->queue, event); ret = 0; } } out: up_read(&user_list_lock); mutex_unlock(&state_lock); wake_up_interruptible(&apm_waitqueue); return ret; } static void apm_suspend(void) { struct apm_user *as; int err = pm_suspend(PM_SUSPEND_MEM); /* * Anyone on the APM queues will think we're still suspended. * Send a message so everyone knows we're now awake again. */ queue_event(APM_NORMAL_RESUME); /* * Finally, wake up anyone who is sleeping on the suspend. */ mutex_lock(&state_lock); down_read(&user_list_lock); list_for_each_entry(as, &apm_user_list, list) { if (as->suspend_state == SUSPEND_WAIT || as->suspend_state == SUSPEND_ACKED) { as->suspend_result = err; as->suspend_state = SUSPEND_DONE; } } up_read(&user_list_lock); mutex_unlock(&state_lock); wake_up(&apm_suspend_waitqueue); } static ssize_t apm_read(struct file *fp, char __user *buf, size_t count, loff_t *ppos) { struct apm_user *as = fp->private_data; apm_event_t event; int i = count, ret = 0; if (count < sizeof(apm_event_t)) return -EINVAL; if (queue_empty(&as->queue) && fp->f_flags & O_NONBLOCK) return -EAGAIN; wait_event_interruptible(apm_waitqueue, !queue_empty(&as->queue)); while ((i >= sizeof(event)) && !queue_empty(&as->queue)) { event = queue_get_event(&as->queue); ret = -EFAULT; if (copy_to_user(buf, &event, sizeof(event))) break; mutex_lock(&state_lock); if (as->suspend_state == SUSPEND_PENDING && (event == APM_SYS_SUSPEND || event == APM_USER_SUSPEND)) as->suspend_state = SUSPEND_READ; mutex_unlock(&state_lock); buf += sizeof(event); i -= sizeof(event); } if (i < count) ret = count - i; return ret; } static unsigned int apm_poll(struct file *fp, poll_table * wait) { struct apm_user *as = fp->private_data; poll_wait(fp, &apm_waitqueue, wait); return queue_empty(&as->queue) ? 0 : POLLIN | POLLRDNORM; } /* * apm_ioctl - handle APM ioctl * * APM_IOC_SUSPEND * This IOCTL is overloaded, and performs two functions. It is used to: * - initiate a suspend * - acknowledge a suspend read from /dev/apm_bios. * Only when everyone who has opened /dev/apm_bios with write permission * has acknowledge does the actual suspend happen. */ static int apm_ioctl(struct inode * inode, struct file *filp, u_int cmd, u_long arg) { struct apm_user *as = filp->private_data; int err = -EINVAL; if (!as->suser || !as->writer) return -EPERM; switch (cmd) { case APM_IOC_SUSPEND: mutex_lock(&state_lock); as->suspend_result = -EINTR; if (as->suspend_state == SUSPEND_READ) { int pending; /* * If we read a suspend command from /dev/apm_bios, * then the corresponding APM_IOC_SUSPEND ioctl is * interpreted as an acknowledge. */ as->suspend_state = SUSPEND_ACKED; suspends_pending--; pending = suspends_pending == 0; mutex_unlock(&state_lock); /* * If there are no further acknowledges required, * suspend the system. */ if (pending) apm_suspend(); /* * Wait for the suspend/resume to complete. If there * are pending acknowledges, we wait here for them. */ freezer_do_not_count(); wait_event(apm_suspend_waitqueue, as->suspend_state == SUSPEND_DONE); /* * Since we are waiting until the suspend is done, the * try_to_freeze() in freezer_count() will not trigger */ freezer_count(); } else { as->suspend_state = SUSPEND_WAIT; mutex_unlock(&state_lock); /* * Otherwise it is a request to suspend the system. * Queue an event for all readers, and expect an * acknowledge from all writers who haven't already * acknowledged. */ err = queue_suspend_event(APM_USER_SUSPEND, as); if (err < 0) { /* * Avoid taking the lock here - this * should be fine. */ as->suspend_state = SUSPEND_NONE; break; } if (err > 0) apm_suspend(); /* * Wait for the suspend/resume to complete. If there * are pending acknowledges, we wait here for them. */ wait_event_freezable(apm_suspend_waitqueue, as->suspend_state == SUSPEND_DONE); } mutex_lock(&state_lock); err = as->suspend_result; as->suspend_state = SUSPEND_NONE; mutex_unlock(&state_lock); break; } return err; } static int apm_release(struct inode * inode, struct file * filp) { struct apm_user *as = filp->private_data; int pending = 0; filp->private_data = NULL; down_write(&user_list_lock); list_del(&as->list); up_write(&user_list_lock); /* * We are now unhooked from the chain. As far as new * events are concerned, we no longer exist. However, we * need to balance suspends_pending, which means the * possibility of sleeping. */ mutex_lock(&state_lock); if (as->suspend_state != SUSPEND_NONE) { suspends_pending -= 1; pending = suspends_pending == 0; } mutex_unlock(&state_lock); if (pending) apm_suspend(); kfree(as); return 0; } static int apm_open(struct inode * inode, struct file * filp) { struct apm_user *as; as = kzalloc(sizeof(*as), GFP_KERNEL); if (as) { /* * XXX - this is a tiny bit broken, when we consider BSD * process accounting. If the device is opened by root, we * instantly flag that we used superuser privs. Who knows, * we might close the device immediately without doing a * privileged operation -- cevans */ as->suser = capable(CAP_SYS_ADMIN); as->writer = (filp->f_mode & FMODE_WRITE) == FMODE_WRITE; as->reader = (filp->f_mode & FMODE_READ) == FMODE_READ; down_write(&user_list_lock); list_add(&as->list, &apm_user_list); up_write(&user_list_lock); filp->private_data = as; } return as ? 0 : -ENOMEM; } static struct file_operations apm_bios_fops = { .owner = THIS_MODULE, .read = apm_read, .poll = apm_poll, .ioctl = apm_ioctl, .open = apm_open, .release = apm_release, }; static struct miscdevice apm_device = { .minor = APM_MINOR_DEV, .name = "apm_bios", .fops = &apm_bios_fops }; #ifdef CONFIG_PROC_FS /* * Arguments, with symbols from linux/apm_bios.h. * * 0) Linux driver version (this will change if format changes) * 1) APM BIOS Version. Usually 1.0, 1.1 or 1.2. * 2) APM flags from APM Installation Check (0x00): * bit 0: APM_16_BIT_SUPPORT * bit 1: APM_32_BIT_SUPPORT * bit 2: APM_IDLE_SLOWS_CLOCK * bit 3: APM_BIOS_DISABLED * bit 4: APM_BIOS_DISENGAGED * 3) AC line status * 0x00: Off-line * 0x01: On-line * 0x02: On backup power (BIOS >= 1.1 only) * 0xff: Unknown * 4) Battery status * 0x00: High * 0x01: Low * 0x02: Critical * 0x03: Charging * 0x04: Selected battery not present (BIOS >= 1.2 only) * 0xff: Unknown * 5) Battery flag * bit 0: High * bit 1: Low * bit 2: Critical * bit 3: Charging * bit 7: No system battery * 0xff: Unknown * 6) Remaining battery life (percentage of charge): * 0-100: valid * -1: Unknown * 7) Remaining battery life (time units): * Number of remaining minutes or seconds * -1: Unknown * 8) min = minutes; sec = seconds */ static int apm_get_info(char *buf, char **start, off_t fpos, int length) { struct apm_power_info info; char *units; int ret; info.ac_line_status = 0xff; info.battery_status = 0xff; info.battery_flag = 0xff; info.battery_life = -1; info.time = -1; info.units = -1; if (apm_get_power_status) apm_get_power_status(&info); switch (info.units) { default: units = "?"; break; case 0: units = "min"; break; case 1: units = "sec"; break; } ret = sprintf(buf, "%s 1.2 0x%02x 0x%02x 0x%02x 0x%02x %d%% %d %s\n", driver_version, APM_32_BIT_SUPPORT, info.ac_line_status, info.battery_status, info.battery_flag, info.battery_life, info.time, units); return ret; } #endif static int kapmd(void *arg) { do { apm_event_t event; int ret; wait_event_interruptible(kapmd_wait, !queue_empty(&kapmd_queue) || kthread_should_stop()); if (kthread_should_stop()) break; spin_lock_irq(&kapmd_queue_lock); event = 0; if (!queue_empty(&kapmd_queue)) event = queue_get_event(&kapmd_queue); spin_unlock_irq(&kapmd_queue_lock); switch (event) { case 0: break; case APM_LOW_BATTERY: case APM_POWER_STATUS_CHANGE: queue_event(event); break; case APM_USER_SUSPEND: case APM_SYS_SUSPEND: ret = queue_suspend_event(event, NULL); if (ret < 0) { /* * We were busy. Try again in 50ms. */ queue_add_event(&kapmd_queue, event); msleep(50); } if (ret > 0) apm_suspend(); break; case APM_CRITICAL_SUSPEND: apm_suspend(); break; } } while (1); return 0; } static int __init apm_init(void) { int ret; if (apm_disabled) { printk(KERN_NOTICE "apm: disabled on user request.\n"); return -ENODEV; } kapmd_tsk = kthread_create(kapmd, NULL, "kapmd"); if (IS_ERR(kapmd_tsk)) { ret = PTR_ERR(kapmd_tsk); kapmd_tsk = NULL; return ret; } wake_up_process(kapmd_tsk); #ifdef CONFIG_PROC_FS create_proc_info_entry("apm", 0, NULL, apm_get_info); #endif ret = misc_register(&apm_device); if (ret != 0) { remove_proc_entry("apm", NULL); kthread_stop(kapmd_tsk); } return ret; } static void __exit apm_exit(void) { misc_deregister(&apm_device); remove_proc_entry("apm", NULL); kthread_stop(kapmd_tsk); } module_init(apm_init); module_exit(apm_exit); MODULE_AUTHOR("Stephen Rothwell"); MODULE_DESCRIPTION("Advanced Power Management"); MODULE_LICENSE("GPL"); #ifndef MODULE static int __init apm_setup(char *str) { while ((str != NULL) && (*str != '\0')) { if (strncmp(str, "off", 3) == 0) apm_disabled = 1; if (strncmp(str, "on", 2) == 0) apm_disabled = 0; str = strchr(str, ','); if (str != NULL) str += strspn(str, ", \t"); } return 1; } __setup("apm=", apm_setup); #endif /** * apm_queue_event - queue an APM event for kapmd * @event: APM event * * Queue an APM event for kapmd to process and ultimately take the * appropriate action. Only a subset of events are handled: * %APM_LOW_BATTERY * %APM_POWER_STATUS_CHANGE * %APM_USER_SUSPEND * %APM_SYS_SUSPEND * %APM_CRITICAL_SUSPEND */ void apm_queue_event(apm_event_t event) { unsigned long flags; spin_lock_irqsave(&kapmd_queue_lock, flags); queue_add_event(&kapmd_queue, event); spin_unlock_irqrestore(&kapmd_queue_lock, flags); wake_up_interruptible(&kapmd_wait); } EXPORT_SYMBOL(apm_queue_event);