/*
* bios-less APM driver for ARM Linux
* Jamey Hicks <jamey@crl.dec.com>
* 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/whdc/archive/amp_12.mspx
*/
#include <linux/module.h>
#include <linux/poll.h>
#include <linux/slab.h>
#include <linux/mutex.h>
#include <linux/proc_fs.h>
#include <linux/seq_file.h>
#include <linux/miscdevice.h>
#include <linux/apm_bios.h>
#include <linux/capability.h>
#include <linux/sched.h>
#include <linux/suspend.h>
#include <linux/apm-emulation.h>
#include <linux/freezer.h>
#include <linux/device.h>
#include <linux/kernel.h>
#include <linux/list.h>
#include <linux/init.h>
#include <linux/completion.h>
#include <linux/kthread.h>
#include <linux/delay.h>
/*
* One option can be changed at boot time as follows:
* 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];
};
/*
* thread states (for threads using a writable /dev/apm_bios fd):
*
* SUSPEND_NONE: nothing happening
* SUSPEND_PENDING: suspend event queued for thread and pending to be read
* SUSPEND_READ: suspend event read, pending acknowledgement
* SUSPEND_ACKED: acknowledgement received from thread (via ioctl),
* waiting for resume
* SUSPEND_ACKTO: acknowledgement timeout
* SUSPEND_DONE: thread had acked suspend and is now notified of
* resume
*
* SUSPEND_WAIT: this thread invoked suspend and is waiting for resume
*
* A thread migrates in one of three paths:
* NONE -1-> PENDING -2-> READ -3-> ACKED -4-> DONE -5-> NONE
* -6-> ACKTO -7-> NONE
* NONE -8-> WAIT -9-> NONE
*
* While in PENDING or READ, the thread is accounted for in the
* suspend_acks_pending counter.
*
* The transitions are invoked as follows:
* 1: suspend event is signalled from the core PM code
* 2: the suspend event is read from the fd by the userspace thread
* 3: userspace thread issues the APM_IOC_SUSPEND ioctl (as ack)
* 4: core PM code signals that we have resumed
* 5: APM_IOC_SUSPEND ioctl returns
*
* 6: the notifier invoked from the core PM code timed out waiting
* for all relevant threds to enter ACKED state and puts those
* that haven't into ACKTO
* 7: those threads issue APM_IOC_SUSPEND ioctl too late,
* get an error
*
* 8: userspace thread issues the APM_IOC_SUSPEND ioctl (to suspend),
* ioctl code invokes pm_suspend()
* 9: pm_suspend() returns indicating resume
*/
enum apm_suspend_state {
SUSPEND_NONE,
SUSPEND_PENDING,
SUSPEND_READ,
SUSPEND_ACKED,
SUSPEND_ACKTO,
SUSPEND_WAIT,
SUSPEND_DONE,
};
/*
* 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;
enum apm_suspend_state suspend_state;
struct apm_queue queue;
};
/*
* Local variables
*/
static atomic_t suspend_acks_pending = ATOMIC_INIT(0);
static atomic_t userspace_notification_inhibit = ATOMIC_INIT(0);
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);
}
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 long
apm_ioctl(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;
switch (as->suspend_state) {
case SUSPEND_READ:
/*
* 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;
atomic_dec(&suspend_acks_pending);
mutex_unlock(&state_lock);
/*
* suspend_acks_pending changed, the notifier needs to
* be woken up for this
*/
wake_up(&apm_suspend_waitqueue);
/*
* Wait for the suspend/resume to complete. If there
* are pending acknowledges, we wait here for them.
* wait_event_freezable() is interruptible and pending
* signal can cause busy looping. We aren't doing
* anything critical, chill a bit on each iteration.
*/
while (wait_event_freezable(apm_suspend_waitqueue,
as->suspend_state != SUSPEND_ACKED))
msleep(10);
break;
case SUSPEND_ACKTO:
as->suspend_result = -ETIMEDOUT;
mutex_unlock(&state_lock);
break;
default:
as->suspend_state = SUSPEND_WAIT;
mutex_unlock(&state_lock);
/*
* Otherwise it is a request to suspend the system.
* Just invoke pm_suspend(), we'll handle it from
* there via the notifier.
*/
as->suspend_result = pm_suspend(PM_SUSPEND_MEM);
}
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;
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.
*/
mutex_lock(&state_lock);
if (as->suspend_state == SUSPEND_PENDING ||
as->suspend_state == SUSPEND_READ)
atomic_dec(&suspend_acks_pending);
mutex_unlock(&state_lock);
wake_up(&apm_suspend_waitqueue);
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 const struct file_operations apm_bios_fops = {
.owner = THIS_MODULE,
.read = apm_read,
.poll = apm_poll,
.unlocked_ioctl = apm_ioctl,
.open = apm_open,
.release = apm_release,
.llseek = noop_llseek,
};
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 proc_apm_show(struct seq_file *m, void *v)
{
struct apm_power_info info;
char *units;
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;
}
seq_printf(m, "%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 0;
}
static int proc_apm_open(struct inode *inode, struct file *file)
{
return single_open(file, proc_apm_show, NULL);
}
static const struct file_operations apm_proc_fops = {
.owner = THIS_MODULE,
.open = proc_apm_open,
.read = seq_read,
.llseek = seq_lseek,
.release = single_release,
};
#endif
static int kapmd(void *arg)
{
do {
apm_event_t event;
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:
pm_suspend(PM_SUSPEND_MEM);
break;
case APM_CRITICAL_SUSPEND:
atomic_inc(&userspace_notification_inhibit);
pm_suspend(PM_SUSPEND_MEM);
atomic_dec(&userspace_notification_inhibit);
break;
}
} while (1);
return 0;
}
static int apm_suspend_notifier(struct notifier_block *nb,
unsigned long event,
void *dummy)
{
struct apm_user *as;
int err;
unsigned long apm_event;
/* short-cut emergency suspends */
if (atomic_read(&userspace_notification_inhibit))
return NOTIFY_DONE;
switch (event) {
case PM_SUSPEND_PREPARE:
case PM_HIBERNATION_PREPARE:
apm_event = (event == PM_SUSPEND_PREPARE) ?
APM_USER_SUSPEND : APM_USER_HIBERNATION;
/*
* Queue an event to all "writer" users that we want
* to suspend and need their ack.
*/
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->reader &&
as->writer && as->suser) {
as->suspend_state = SUSPEND_PENDING;
atomic_inc(&suspend_acks_pending);
queue_add_event(&as->queue, apm_event);
}
}
up_read(&user_list_lock);
mutex_unlock(&state_lock);
wake_up_interruptible(&apm_waitqueue);
/*
* Wait for the the suspend_acks_pending variable to drop to
* zero, meaning everybody acked the suspend event (or the
* process was killed.)
*
* If the app won't answer within a short while we assume it
* locked up and ignore it.
*/
err = wait_event_interruptible_timeout(
apm_suspend_waitqueue,
atomic_read(&suspend_acks_pending) == 0,
5*HZ);
/* timed out */
if (err == 0) {
/*
* Move anybody who timed out to "ack timeout" state.
*
* We could time out and the userspace does the ACK
* right after we time out but before we enter the
* locked section here, but that's fine.
*/
mutex_lock(&state_lock);
down_read(&user_list_lock);
list_for_each_entry(as, &apm_user_list, list) {
if (as->suspend_state == SUSPEND_PENDING ||
as->suspend_state == SUSPEND_READ) {
as->suspend_state = SUSPEND_ACKTO;
atomic_dec(&suspend_acks_pending);
}
}
up_read(&user_list_lock);
mutex_unlock(&state_lock);
}
/* let suspend proceed */
if (err >= 0)
return NOTIFY_OK;
/* interrupted by signal */
return notifier_from_errno(err);
case PM_POST_SUSPEND:
case PM_POST_HIBERNATION:
apm_event = (event == PM_POST_SUSPEND) ?
APM_NORMAL_RESUME : APM_HIBERNATION_RESUME;
/*
* 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_event);
/*
* 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_ACKED) {
/*
* TODO: maybe grab error code, needs core
* changes to push the error to the notifier
* chain (could use the second parameter if
* implemented)
*/
as->suspend_result = 0;
as->suspend_state = SUSPEND_DONE;
}
}
up_read(&user_list_lock);
mutex_unlock(&state_lock);
wake_up(&apm_suspend_waitqueue);
return NOTIFY_OK;
default:
return NOTIFY_DONE;
}
}
static struct notifier_block apm_notif_block = {
.notifier_call = apm_suspend_notifier,
};
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;
goto out;
}
wake_up_process(kapmd_tsk);
#ifdef CONFIG_PROC_FS
proc_create("apm", 0, NULL, &apm_proc_fops);
#endif
ret = misc_register(&apm_device);
if (ret)
goto out_stop;
ret = register_pm_notifier(&apm_notif_block);
if (ret)
goto out_unregister;
return 0;
out_unregister:
misc_deregister(&apm_device);
out_stop:
remove_proc_entry("apm", NULL);
kthread_stop(kapmd_tsk);
out:
return ret;
}
static void __exit apm_exit(void)
{
unregister_pm_notifier(&apm_notif_block);
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);
