/*
* bios-less APM driver for ARM Linux
*/
#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>
/*
* The apm_bios device is one of the misc char devices.
* This is its minor number.
*/
#define APM_MINOR_DEV 134
/*
* 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-