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|
/*
* 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/pm.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);
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