/*
* Updates the cached state of a character device
* based on sensor data. Must be called with the
* character device state lock held.
*/
static int lunix_chrdev_state_update(struct lunix_chrdev_state_struct *state)
{
//struct lunix_sensor_struct *sensor;
unsigned long flags;
int need_refresh, n;
long int data;
uint32_t raw_data, raw_time;
char c;
debug("entering lunix_chrdev_state_update\n");
/*
* Grab the raw data quickly, hold the
* spinlock for as little as possible.
*/
/* ? */
/* Why use spinlocks? See LDD3, p. 119 */
/*
* Any new data available?
*/
/* ? */
need_refresh = lunix_chrdev_state_needs_refresh(state);
if (need_refresh) {
debug("Spinlock almost at hand.\n");
spin_lock_irqsave(&(state->sensor->lock), flags);
debug("Spinlock at hand.\n");
raw_data = state->sensor->msr_data[state->type]->values[0];
raw_time = state->sensor->msr_data[state->type]->last_update;
spin_unlock_irqrestore(&(state->sensor->lock), flags);
}
else {
debug("Again!\n");
return -EAGAIN; /* No new data */
}
/*
* Now we can take our time to format them,
* holding only the private state semaphore
*/
/* ? */
switch(state->type) {
debug("case 0\n");
case BATT: data = lookup_voltage[raw_data]; break;
debug("case 1\n");
case TEMP: data = lookup_temperature[raw_data]; break;
debug("case 2\n");
case LIGHT: data = lookup_light[raw_data]; break;
default: ;
debug("case default\n");
}
c = (data >= 0) ? '+' : '-';
data = (data > 0) ? data : (-data);
n = sprintf(state->buf_data, "%c%ld.%ld\n", c, data/1000, data%1000 );
state->buf_timestamp = raw_time;
state->buf_lim = n;
debug("leaving\n");
return 0;
}
static ssize_t lunix_chrdev_read(struct file *filp, char __user *usrbuf, size_t cnt, loff_t *f_pos)
{
ssize_t ret;
struct lunix_sensor_struct *sensor;
struct lunix_chrdev_state_struct *state;
int di,bytes;
debug("entering\n");
state = filp->private_data;
WARN_ON(!state);
sensor = state->sensor;
WARN_ON(!sensor);
/* Lock? */
di = down_interruptible(&(state->lock));
if (di) {
/* Failed to V */
debug("failed down_interruptible\n");
ret = -EINTR;
goto out;
}
/*
* If the cached character device state needs to be
* updated by actual sensor data (i.e. we need to report
* on a "fresh" measurement, do so
*/
if (*f_pos == 0) {
while (lunix_chrdev_state_update(state) == -EAGAIN) {
/* ? */
/* The process needs to sleep */
/* See LDD3, page 153 for a hint */
up(&(state->lock));
if (wait_event_interruptible(sensor->wq, lunix_chrdev_state_needs_refresh(state)))
return -ERESTARTSYS; /* signal: tell the fs layer to handle it */
di = down_interruptible(&(state->lock));
if (di) {
/* Failed to V */
debug("failed down_interruptible\n");
ret = -EINTR;
goto out;
}
}
}
debug("ready to copy_to_user\n");
bytes = (cnt < state->buf_lim - *f_pos) ? cnt : state->buf_lim-*f_pos;
ret = copy_to_user(usrbuf, state->buf_data + *f_pos, bytes);
if (ret) {
/* Failed to copy */
debug("copy_to_user failed\n");
}
/* Auto-rewind on EOF mode? */
/* ? */
(*f_pos)+=bytes;
if(*f_pos >= state->buf_lim) *f_pos=0;
ret = bytes;
out:
/* Unlock? */
up(&(state->lock));
return ret;
}
/*
* Updates the cached state of a character device
* based on sensor data. Must be called with the
* character device state lock held.
*/
static int lunix_chrdev_state_update(struct lunix_chrdev_state_struct *state)
{
struct lunix_sensor_struct *sensor;
unsigned long flags;
int new_data;
uint16_t portion; /* fract_portion; */
long res ; /* res_fract */
uint32_t temp, temp1 ;
unsigned char temp_buf[20];
/*
* Grab the raw data quickly, hold the
* spinlock for as little as possible.
*/
/* ? */
/* Why use spinlocks? See LDD3, p. 119 */
debug("going into lunix_chrdev_state_update \n ");
spin_lock_irqsave(&sensor->lock, flags );
/*
* Any new data available?
*/
/* ? */
new_data = lunix_chrdev_state_needs_refresh(&state);
spin_unlock_irqrestore(&sensor->lock, flags);
/*
* Now we can take our time to format them,
* holding only the private state semaphore
*/
/* ? */
if (down_interruptible(&state->lock)) {
debug("Could not acquire lock\n");
return -ERESTARTSYS;
}
if ((new_data) == 1) {
debug("there is new data")
memcpy(&temp1,((sensor->msr_data[state->type])->values[0]), 4);
temp = cpu_to_le32(temp1);
memcpy(&portion,&temp,2);
/* temp = temp >> 16; */
/* memcpy(&integ_portion,&temp,2); */
if ((state->type) == 0 ) {
res = uint16_to_batt(portion);
/* res_fract = uint16_to_batt(fract_portion); */
}
if ((state->type) == 1 ){
res = uint16_to_temp(portion);
/* res_fract = uint16_to_temp(fract_portion); */
}
if ((state->type) == 2 ){
res = uint16_to_light(portion);
/* res_fract = uint16_to_light(fract_portion); */
}
up(&state->lock);
sprintf(temp_buf, "%ld" , res);
(state->buf_lim) = strlen(temp_buf);
memcpy((state->buf_data), &temp_buf, (state->buf_lim));
return 0;
}
else {
up(&state->lock);
return -EAGAIN;
}
debug("leaving\n");
return 0;
}