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/*
* libusual
*
* The libusual contains the table of devices common for ub and usb-storage.
*/
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/usb.h>
#include <linux/usb_usual.h>
#include <linux/vmalloc.h>
#include <linux/kthread.h>
#include <linux/mutex.h>
/*
*/
#define USU_MOD_FL_THREAD 1 /* Thread is running */
#define USU_MOD_FL_PRESENT 2 /* The module is loaded */
struct mod_status {
unsigned long fls;
};
static struct mod_status stat[3];
static DEFINE_SPINLOCK(usu_lock);
/*
*/
#define USB_US_DEFAULT_BIAS USB_US_TYPE_STOR
static atomic_t usu_bias = ATOMIC_INIT(USB_US_DEFAULT_BIAS);
#define BIAS_NAME_SIZE (sizeof("usb-storage"))
static const char *bias_names[3] = { "none", "usb-storage", "ub" };
static DEFINE_MUTEX(usu_probe_mutex);
static DECLARE_COMPLETION(usu_end_notify);
static atomic_t total_threads = ATOMIC_INIT(0);
static int usu_probe_thread(void *arg);
/*
* @type: the module type as an integer
*/
void usb_usual_set_present(int type)
{
struct mod_status *st;
unsigned long flags;
if (type <= 0 || type >= 3)
return;
st = &stat[type];
spin_lock_irqsave(&usu_lock, flags);
st->fls |= USU_MOD_FL_PRESENT;
spin_unlock_irqrestore(&usu_lock, flags);
}
EXPORT_SYMBOL_GPL(usb_usual_set_present);
void usb_usual_clear_present(int type)
{
struct mod_status *st;
unsigned long flags;
if (type <= 0 || type >= 3)
return;
st = &stat[type];
spin_lock_irqsave(&usu_lock, flags);
st->fls &= ~USU_MOD_FL_PRESENT;
spin_unlock_irqrestore(&usu_lock, flags);
}
EXPORT_SYMBOL_GPL(usb_usual_clear_present);
/*
* Match the calling driver type against the table.
* Returns: 0 if the device matches.
*/
int usb_usual_check_type(const struct usb_device_id *id, int caller_type)
{
int id_type = USB_US_TYPE(id->driver_info);
if (caller_type <= 0 || caller_type >= 3)
return -EINVAL;
/* Drivers grab fixed assignment devices */
if (id_type == caller_type)
return 0;
/* Drivers grab devices biased to them */
if (id_type == USB_US_TYPE_NONE && caller_type == atomic_read(&usu_bias))
return 0;
return -ENODEV;
}
EXPORT_SYMBOL_GPL(usb_usual_check_type);
/*
*/
static int usu_probe(struct usb_interface *intf,
const struct usb_device_id *id)
{
int rc;
unsigned long type;
struct task_struct* task;
unsigned long flags;
type = USB_US_TYPE(id->driver_info);
if (type == 0)
type = atomic_read(&usu_bias);
spin_lock_irqsave(&usu_lock, flags);
if ((stat[type].fls & (USU_MOD_FL_THREAD|USU_MOD_FL_PRESENT)) != 0) {
spin_unlock_irqrestore(&usu_lock, flags);
return -ENXIO;
}
stat[type].fls |= USU_MOD_FL_THREAD;
spin_unlock_irqrestore(&usu_lock, flags);
task = kthread_run(usu_probe_thread, (void*)type, "libusual_%ld", type);
if (IS_ERR(task)) {
rc = PTR_ERR(task);
printk(KERN_WARNING "libusual: "
"Unable to start the thread for %s: %d\n",
bias_names[type], rc);
spin_lock_irqsave(&usu_lock, flags);
stat[type].fls &= ~USU_MOD_FL_THREAD;
spin_unlock_irqrestore(&usu_lock, flags);
return rc; /* Not being -ENXIO causes a message printed */
}
atomic_inc(&total_threads);
return -ENXIO;
}
static void usu_disconnect(struct usb_interface *intf)
{
; /* We should not be here. */
}
static struct usb_driver usu_driver = {
.name = "libusual",
.probe = usu_probe,
.disconnect = usu_disconnect,
.id_table = usb_storage_usb_ids,
};
/*
* A whole new thread for a purpose of request_module seems quite stupid.
* The request_module forks once inside again. However, if we attempt
* to load a storage module from our own modprobe thread, that module
* references our symbols, which cannot be resolved until our module is
* initialized. I wish there was a way to wait for the end of initialization.
* The module notifier reports MODULE_STATE_COMING only.
* So, we wait until module->init ends as the next best thing.
*/
static int usu_probe_thread(void *arg)
{
int type = (unsigned long) arg;
struct mod_status *st = &stat[type];
int rc;
unsigned long flags;
mutex_lock(&usu_probe_mutex);
rc = request_module(bias_names[type]);
spin_lock_irqsave(&usu_lock, flags);
if (rc == 0 && (st->fls & USU_MOD_FL_PRESENT) == 0) {
/*
* This should not happen, but let us keep tabs on it.
*/
printk(KERN_NOTICE "libusual: "
"modprobe for %s succeeded, but module is not present\n",
bias_names[type]);
}
st->fls &= ~USU_MOD_FL_THREAD;
spin_unlock_irqrestore(&usu_lock, flags);
mutex_unlock(&usu_probe_mutex);
complete_and_exit(&usu_end_notify, 0);
}
/*
*/
static int __init usb_usual_init(void)
{
int rc;
mutex_lock(&usu_probe_mutex);
rc = usb_register(&usu_driver);
mutex_unlock(&usu_probe_mutex);
return rc;
}
static void __exit usb_usual_exit(void)
{
/*
* We do not check for any drivers present, because
* they keep us pinned with symbol references.
*/
usb_deregister(&usu_driver);
while (atomic_read(&total_threads) > 0) {
wait_for_completion(&usu_end_notify);
atomic_dec(&total_threads);
}
}
/*
* Validate and accept the bias parameter.
*/
static int usu_set_bias(const char *bias_s, struct kernel_param *kp)
{
int i;
int len;
int bias_n = 0;
len = strlen(bias_s);
if (len == 0)
return -EDOM;
if (bias_s[len-1] == '\n')
--len;
for (i = 1; i < 3; i++) {
if (strncmp(bias_s, bias_names[i], len) == 0) {
bias_n = i;
break;
}
}
if (bias_n == 0)
return -EINVAL;
atomic_set(&usu_bias, bias_n);
return 0;
}
static int usu_get_bias(char *buffer, struct kernel_param *kp)
{
return strlen(strcpy(buffer, bias_names[atomic_read(&usu_bias)]));
}
module_init(usb_usual_init);
module_exit(usb_usual_exit);
module_param_call(bias, usu_set_bias, usu_get_bias, NULL, S_IRUGO|S_IWUSR);
__MODULE_PARM_TYPE(bias, "string");
MODULE_PARM_DESC(bias, "Bias to usb-storage or ub");
MODULE_LICENSE("GPL");
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