/*
* 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/hwdev/busbios/amp_12.htm]
*/
#include <linux/module.h>
#include <linux/poll.h>
#include <linux/slab.h>
#include <linux/proc_fs.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>
#include <asm/system.h>
/*
* 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);
