![David Howells](/assets/img/avatar_default.png)
Maintain a per-CPU global "struct pt_regs *" variable which can be used instead of passing regs around manually through all ~1800 interrupt handlers in the Linux kernel. The regs pointer is used in few places, but it potentially costs both stack space and code to pass it around. On the FRV arch, removing the regs parameter from all the genirq function results in a 20% speed up of the IRQ exit path (ie: from leaving timer_interrupt() to leaving do_IRQ()). Where appropriate, an arch may override the generic storage facility and do something different with the variable. On FRV, for instance, the address is maintained in GR28 at all times inside the kernel as part of general exception handling. Having looked over the code, it appears that the parameter may be handed down through up to twenty or so layers of functions. Consider a USB character device attached to a USB hub, attached to a USB controller that posts its interrupts through a cascaded auxiliary interrupt controller. A character device driver may want to pass regs to the sysrq handler through the input layer which adds another few layers of parameter passing. I've build this code with allyesconfig for x86_64 and i386. I've runtested the main part of the code on FRV and i386, though I can't test most of the drivers. I've also done partial conversion for powerpc and MIPS - these at least compile with minimal configurations. This will affect all archs. Mostly the changes should be relatively easy. Take do_IRQ(), store the regs pointer at the beginning, saving the old one: struct pt_regs *old_regs = set_irq_regs(regs); And put the old one back at the end: set_irq_regs(old_regs); Don't pass regs through to generic_handle_irq() or __do_IRQ(). In timer_interrupt(), this sort of change will be necessary: - update_process_times(user_mode(regs)); - profile_tick(CPU_PROFILING, regs); + update_process_times(user_mode(get_irq_regs())); + profile_tick(CPU_PROFILING); I'd like to move update_process_times()'s use of get_irq_regs() into itself, except that i386, alone of the archs, uses something other than user_mode(). Some notes on the interrupt handling in the drivers: (*) input_dev() is now gone entirely. The regs pointer is no longer stored in the input_dev struct. (*) finish_unlinks() in drivers/usb/host/ohci-q.c needs checking. It does something different depending on whether it's been supplied with a regs pointer or not. (*) Various IRQ handler function pointers have been moved to type irq_handler_t. Signed-Off-By: David Howells <dhowells@redhat.com> (cherry picked from 1b16e7ac850969f38b375e511e3fa2f474a33867 commit)
403 lines
9 KiB
C
403 lines
9 KiB
C
/*
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* Raw serio device providing access to a raw byte stream from underlying
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* serio port. Closely emulates behavior of pre-2.6 /dev/psaux device
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*
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* Copyright (c) 2004 Dmitry Torokhov
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*
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* This program is free software; you can redistribute it and/or modify it
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* under the terms of the GNU General Public License version 2 as published by
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* the Free Software Foundation.
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*/
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#include <linux/slab.h>
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#include <linux/poll.h>
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#include <linux/module.h>
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#include <linux/serio.h>
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#include <linux/init.h>
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#include <linux/major.h>
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#include <linux/device.h>
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#include <linux/miscdevice.h>
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#include <linux/wait.h>
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#include <linux/mutex.h>
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#define DRIVER_DESC "Raw serio driver"
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MODULE_AUTHOR("Dmitry Torokhov <dtor@mail.ru>");
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MODULE_DESCRIPTION(DRIVER_DESC);
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MODULE_LICENSE("GPL");
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#define SERIO_RAW_QUEUE_LEN 64
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struct serio_raw {
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unsigned char queue[SERIO_RAW_QUEUE_LEN];
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unsigned int tail, head;
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char name[16];
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unsigned int refcnt;
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struct serio *serio;
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struct miscdevice dev;
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wait_queue_head_t wait;
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struct list_head list;
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struct list_head node;
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};
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struct serio_raw_list {
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struct fasync_struct *fasync;
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struct serio_raw *serio_raw;
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struct list_head node;
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};
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static DEFINE_MUTEX(serio_raw_mutex);
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static LIST_HEAD(serio_raw_list);
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static unsigned int serio_raw_no;
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/*********************************************************************
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* Interface with userspace (file operations) *
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*********************************************************************/
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static int serio_raw_fasync(int fd, struct file *file, int on)
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{
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struct serio_raw_list *list = file->private_data;
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int retval;
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retval = fasync_helper(fd, file, on, &list->fasync);
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return retval < 0 ? retval : 0;
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}
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static struct serio_raw *serio_raw_locate(int minor)
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{
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struct serio_raw *serio_raw;
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list_for_each_entry(serio_raw, &serio_raw_list, node) {
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if (serio_raw->dev.minor == minor)
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return serio_raw;
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}
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return NULL;
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}
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static int serio_raw_open(struct inode *inode, struct file *file)
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{
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struct serio_raw *serio_raw;
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struct serio_raw_list *list;
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int retval = 0;
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retval = mutex_lock_interruptible(&serio_raw_mutex);
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if (retval)
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return retval;
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if (!(serio_raw = serio_raw_locate(iminor(inode)))) {
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retval = -ENODEV;
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goto out;
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}
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if (!serio_raw->serio) {
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retval = -ENODEV;
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goto out;
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}
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if (!(list = kzalloc(sizeof(struct serio_raw_list), GFP_KERNEL))) {
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retval = -ENOMEM;
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goto out;
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}
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list->serio_raw = serio_raw;
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file->private_data = list;
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serio_raw->refcnt++;
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list_add_tail(&list->node, &serio_raw->list);
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out:
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mutex_unlock(&serio_raw_mutex);
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return retval;
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}
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static int serio_raw_cleanup(struct serio_raw *serio_raw)
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{
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if (--serio_raw->refcnt == 0) {
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misc_deregister(&serio_raw->dev);
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list_del_init(&serio_raw->node);
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kfree(serio_raw);
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return 1;
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}
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return 0;
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}
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static int serio_raw_release(struct inode *inode, struct file *file)
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{
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struct serio_raw_list *list = file->private_data;
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struct serio_raw *serio_raw = list->serio_raw;
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mutex_lock(&serio_raw_mutex);
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serio_raw_fasync(-1, file, 0);
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serio_raw_cleanup(serio_raw);
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mutex_unlock(&serio_raw_mutex);
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return 0;
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}
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static int serio_raw_fetch_byte(struct serio_raw *serio_raw, char *c)
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{
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unsigned long flags;
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int empty;
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spin_lock_irqsave(&serio_raw->serio->lock, flags);
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empty = serio_raw->head == serio_raw->tail;
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if (!empty) {
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*c = serio_raw->queue[serio_raw->tail];
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serio_raw->tail = (serio_raw->tail + 1) % SERIO_RAW_QUEUE_LEN;
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}
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spin_unlock_irqrestore(&serio_raw->serio->lock, flags);
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return !empty;
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}
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static ssize_t serio_raw_read(struct file *file, char __user *buffer, size_t count, loff_t *ppos)
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{
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struct serio_raw_list *list = file->private_data;
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struct serio_raw *serio_raw = list->serio_raw;
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char c;
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ssize_t retval = 0;
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if (!serio_raw->serio)
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return -ENODEV;
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if (serio_raw->head == serio_raw->tail && (file->f_flags & O_NONBLOCK))
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return -EAGAIN;
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retval = wait_event_interruptible(list->serio_raw->wait,
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serio_raw->head != serio_raw->tail || !serio_raw->serio);
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if (retval)
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return retval;
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if (!serio_raw->serio)
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return -ENODEV;
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while (retval < count && serio_raw_fetch_byte(serio_raw, &c)) {
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if (put_user(c, buffer++))
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return -EFAULT;
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retval++;
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}
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return retval;
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}
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static ssize_t serio_raw_write(struct file *file, const char __user *buffer, size_t count, loff_t *ppos)
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{
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struct serio_raw_list *list = file->private_data;
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ssize_t written = 0;
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int retval;
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unsigned char c;
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retval = mutex_lock_interruptible(&serio_raw_mutex);
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if (retval)
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return retval;
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if (!list->serio_raw->serio) {
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retval = -ENODEV;
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goto out;
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}
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if (count > 32)
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count = 32;
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while (count--) {
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if (get_user(c, buffer++)) {
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retval = -EFAULT;
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goto out;
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}
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if (serio_write(list->serio_raw->serio, c)) {
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retval = -EIO;
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goto out;
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}
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written++;
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};
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out:
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mutex_unlock(&serio_raw_mutex);
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return written;
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}
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static unsigned int serio_raw_poll(struct file *file, poll_table *wait)
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{
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struct serio_raw_list *list = file->private_data;
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poll_wait(file, &list->serio_raw->wait, wait);
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if (list->serio_raw->head != list->serio_raw->tail)
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return POLLIN | POLLRDNORM;
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return 0;
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}
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static struct file_operations serio_raw_fops = {
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.owner = THIS_MODULE,
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.open = serio_raw_open,
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.release = serio_raw_release,
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.read = serio_raw_read,
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.write = serio_raw_write,
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.poll = serio_raw_poll,
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.fasync = serio_raw_fasync,
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};
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/*********************************************************************
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* Interface with serio port *
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*********************************************************************/
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static irqreturn_t serio_raw_interrupt(struct serio *serio, unsigned char data,
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unsigned int dfl)
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{
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struct serio_raw *serio_raw = serio_get_drvdata(serio);
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struct serio_raw_list *list;
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unsigned int head = serio_raw->head;
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/* we are holding serio->lock here so we are prootected */
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serio_raw->queue[head] = data;
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head = (head + 1) % SERIO_RAW_QUEUE_LEN;
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if (likely(head != serio_raw->tail)) {
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serio_raw->head = head;
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list_for_each_entry(list, &serio_raw->list, node)
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kill_fasync(&list->fasync, SIGIO, POLL_IN);
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wake_up_interruptible(&serio_raw->wait);
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}
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return IRQ_HANDLED;
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}
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static int serio_raw_connect(struct serio *serio, struct serio_driver *drv)
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{
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struct serio_raw *serio_raw;
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int err;
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if (!(serio_raw = kzalloc(sizeof(struct serio_raw), GFP_KERNEL))) {
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printk(KERN_ERR "serio_raw.c: can't allocate memory for a device\n");
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return -ENOMEM;
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}
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mutex_lock(&serio_raw_mutex);
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snprintf(serio_raw->name, sizeof(serio_raw->name), "serio_raw%d", serio_raw_no++);
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serio_raw->refcnt = 1;
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serio_raw->serio = serio;
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INIT_LIST_HEAD(&serio_raw->list);
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init_waitqueue_head(&serio_raw->wait);
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serio_set_drvdata(serio, serio_raw);
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err = serio_open(serio, drv);
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if (err)
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goto out_free;
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list_add_tail(&serio_raw->node, &serio_raw_list);
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serio_raw->dev.minor = PSMOUSE_MINOR;
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serio_raw->dev.name = serio_raw->name;
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serio_raw->dev.dev = &serio->dev;
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serio_raw->dev.fops = &serio_raw_fops;
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err = misc_register(&serio_raw->dev);
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if (err) {
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serio_raw->dev.minor = MISC_DYNAMIC_MINOR;
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err = misc_register(&serio_raw->dev);
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}
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if (err) {
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printk(KERN_INFO "serio_raw: failed to register raw access device for %s\n",
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serio->phys);
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goto out_close;
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}
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printk(KERN_INFO "serio_raw: raw access enabled on %s (%s, minor %d)\n",
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serio->phys, serio_raw->name, serio_raw->dev.minor);
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goto out;
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out_close:
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serio_close(serio);
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list_del_init(&serio_raw->node);
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out_free:
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serio_set_drvdata(serio, NULL);
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kfree(serio_raw);
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out:
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mutex_unlock(&serio_raw_mutex);
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return err;
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}
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static int serio_raw_reconnect(struct serio *serio)
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{
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struct serio_raw *serio_raw = serio_get_drvdata(serio);
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struct serio_driver *drv = serio->drv;
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if (!drv || !serio_raw) {
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printk(KERN_DEBUG "serio_raw: reconnect request, but serio is disconnected, ignoring...\n");
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return -1;
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}
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/*
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* Nothing needs to be done here, we just need this method to
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* keep the same device.
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*/
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return 0;
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}
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static void serio_raw_disconnect(struct serio *serio)
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{
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struct serio_raw *serio_raw;
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mutex_lock(&serio_raw_mutex);
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serio_raw = serio_get_drvdata(serio);
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serio_close(serio);
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serio_set_drvdata(serio, NULL);
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serio_raw->serio = NULL;
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if (!serio_raw_cleanup(serio_raw))
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wake_up_interruptible(&serio_raw->wait);
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mutex_unlock(&serio_raw_mutex);
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}
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static struct serio_device_id serio_raw_serio_ids[] = {
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{
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.type = SERIO_8042,
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.proto = SERIO_ANY,
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.id = SERIO_ANY,
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.extra = SERIO_ANY,
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},
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{ 0 }
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};
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MODULE_DEVICE_TABLE(serio, serio_raw_serio_ids);
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static struct serio_driver serio_raw_drv = {
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.driver = {
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.name = "serio_raw",
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},
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.description = DRIVER_DESC,
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.id_table = serio_raw_serio_ids,
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.interrupt = serio_raw_interrupt,
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.connect = serio_raw_connect,
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.reconnect = serio_raw_reconnect,
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.disconnect = serio_raw_disconnect,
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.manual_bind = 1,
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};
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static int __init serio_raw_init(void)
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{
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serio_register_driver(&serio_raw_drv);
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return 0;
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}
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static void __exit serio_raw_exit(void)
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{
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serio_unregister_driver(&serio_raw_drv);
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}
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module_init(serio_raw_init);
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module_exit(serio_raw_exit);
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