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common.c
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common.c
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/* Implementation of common driver functionality.
*/
#include "common.h"
#include <linux/freezer.h>
#include <linux/hrtimer.h>
#include <linux/moduleparam.h>
#include <linux/slab.h>
#include <linux/usb.h>
#include <linux/wait.h>
#include <linux/workqueue.h>
#define UPDATE_INTERVAL_DEFAULT_MS ((u64) 1000)
#define UPDATE_INTERVAL_MIN_MS ((u64) 500)
static ssize_t update_interval_show(struct device *dev,
struct device_attribute *attr, char *buf)
{
struct usb_kraken *kraken = usb_get_intfdata(to_usb_interface(dev));
const s64 interval_ms = ktime_to_ms(kraken->update_interval);
return scnprintf(buf, PAGE_SIZE, "%lld\n", interval_ms);
}
static ssize_t
update_interval_store(struct device *dev, struct device_attribute *attr,
const char *buf, size_t count)
{
ktime_t interval_old;
struct usb_kraken *kraken = usb_get_intfdata(to_usb_interface(dev));
u64 interval_ms;
int ret = kstrtoull(buf, 0, &interval_ms);
if (ret)
return ret;
// interval is 0: halt updates
if (interval_ms == 0) {
hrtimer_cancel(&kraken->update_timer);
kraken->update_interval = ktime_set(0, 0);
dev_info(dev, "halting updates: interval set to 0\n");
return count;
}
// interval not 0: save interval in kraken
interval_old = kraken->update_interval;
kraken->update_interval = ms_to_ktime(
max(interval_ms, UPDATE_INTERVAL_MIN_MS));
// and restart updates if they'd been halted
if (ktime_compare(interval_old, ktime_set(0, 0)) == 0)
dev_info(dev, "restarting updates: interval set to non-0\n");
hrtimer_start(&kraken->update_timer, kraken->update_interval,
HRTIMER_MODE_REL);
return count;
}
static DEVICE_ATTR_RW(update_interval);
/* Initial value of attribute `update_interval`, settable as a parameter.
*/
static ulong update_interval_initial = UPDATE_INTERVAL_DEFAULT_MS;
module_param_named(update_interval, update_interval_initial, ulong, 0);
static ssize_t update_sync_show(struct device *dev,
struct device_attribute *attr, char *buf)
{
struct usb_kraken *kraken = usb_get_intfdata(to_usb_interface(dev));
int ret;
kraken->update_sync_condition = false;
ret = !wait_event_interruptible(kraken->update_sync_waitqueue,
kraken->update_sync_condition);
return scnprintf(buf, PAGE_SIZE, "%d\n", ret);
}
static DEVICE_ATTR_RO(update_sync);
static int kraken_create_device_files(struct usb_interface *interface)
{
int retval;
if ((retval = device_create_file(&interface->dev,
&dev_attr_update_interval)))
goto error_update_interval;
if ((retval = device_create_file(&interface->dev,
&dev_attr_update_sync)))
goto error_update_sync;
if ((retval = kraken_driver_create_device_files(interface)))
goto error_driver_files;
return 0;
error_driver_files:
device_remove_file(&interface->dev, &dev_attr_update_sync);
error_update_sync:
device_remove_file(&interface->dev, &dev_attr_update_sync);
error_update_interval:
return retval;
}
static void kraken_remove_device_files(struct usb_interface *interface)
{
kraken_driver_remove_device_files(interface);
device_remove_file(&interface->dev, &dev_attr_update_sync);
device_remove_file(&interface->dev, &dev_attr_update_interval);
}
static enum hrtimer_restart kraken_update_timer(struct hrtimer *update_timer)
{
bool retval;
struct usb_kraken *kraken
= container_of(update_timer, struct usb_kraken, update_timer);
// last update failed: halt updates
if (kraken->update_retval) {
dev_err(&kraken->udev->dev,
"halting updates: last update failed: %d\n",
kraken->update_retval);
kraken->update_retval = 0;
kraken->update_interval = ktime_set(0, 0);
return HRTIMER_NORESTART;
}
// otherwise: queue new update and restart timer
retval = queue_work(kraken->update_workqueue, &kraken->update_work);
if (!retval)
dev_warn(&kraken->udev->dev, "work already on a queue\n");
hrtimer_forward(update_timer, ktime_get(), kraken->update_interval);
return HRTIMER_RESTART;
}
static void kraken_update_work(struct work_struct *update_work)
{
struct usb_kraken *kraken
= container_of(update_work, struct usb_kraken, update_work);
kraken->update_retval = kraken_driver_update(kraken);
// tell any waiting update syncs that the update has finished
kraken->update_sync_condition = true;
wake_up_interruptible_all(&kraken->update_sync_waitqueue);
}
int kraken_probe(struct usb_interface *interface,
const struct usb_device_id *id)
{
char workqueue_name[64];
int retval = -ENOMEM;
struct usb_device *udev = interface_to_usbdev(interface);
struct usb_kraken *kraken = kmalloc(sizeof(*kraken), GFP_KERNEL);
if (kraken == NULL)
goto error_kraken;
kraken->udev = usb_get_dev(udev);
usb_set_intfdata(interface, kraken);
retval = kraken_driver_probe(interface, id);
if (retval)
goto error_driver_probe;
retval = kraken_create_device_files(interface);
if (retval) {
dev_err(&interface->dev,
"failed to create device files: %d\n", retval);
goto error_create_files;
}
init_waitqueue_head(&kraken->update_sync_waitqueue);
kraken->update_sync_condition = false;
snprintf(workqueue_name, sizeof(workqueue_name),
"%s_up", kraken_driver_name);
kraken->update_workqueue
= create_singlethread_workqueue(workqueue_name);
INIT_WORK(&kraken->update_work, &kraken_update_work);
hrtimer_init(&kraken->update_timer, CLOCK_MONOTONIC, HRTIMER_MODE_REL);
kraken->update_timer.function = &kraken_update_timer;
if (update_interval_initial == 0) {
kraken->update_interval = ktime_set(0, 0);
dev_info(&interface->dev,
"not starting updates: interval set to 0\n");
} else {
kraken->update_interval = ms_to_ktime(
max((u64) update_interval_initial,
UPDATE_INTERVAL_MIN_MS));
hrtimer_start(&kraken->update_timer, kraken->update_interval,
HRTIMER_MODE_REL);
}
kraken->update_retval = 0;
return 0;
error_create_files:
kraken_driver_disconnect(interface);
error_driver_probe:
usb_set_intfdata(interface, NULL);
usb_put_dev(kraken->udev);
kfree(kraken);
error_kraken:
return retval;
}
void kraken_disconnect(struct usb_interface *interface)
{
struct usb_kraken *kraken = usb_get_intfdata(interface);
hrtimer_cancel(&kraken->update_timer);
flush_workqueue(kraken->update_workqueue);
destroy_workqueue(kraken->update_workqueue);
kraken->update_sync_condition = true;
wake_up_all(&kraken->update_sync_waitqueue);
kraken_remove_device_files(interface);
kraken_driver_disconnect(interface);
usb_set_intfdata(interface, NULL);
usb_put_dev(kraken->udev);
kfree(kraken);
}