+++ /dev/null
-/* drivers/char/dcc_tty.c
- *
- * Copyright (C) 2007 Google, Inc.
- *
- * This software is licensed under the terms of the GNU General Public
- * License version 2, as published by the Free Software Foundation, and
- * may be copied, distributed, and modified under those terms.
- *
- * This program is distributed in the hope that it will be useful,
- * but WITHOUT ANY WARRANTY; without even the implied warranty of
- * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
- * GNU General Public License for more details.
- *
- */
-
-#include <linux/module.h>
-#include <linux/platform_device.h>
-#include <linux/delay.h>
-#include <linux/console.h>
-#include <linux/hrtimer.h>
-#include <linux/tty.h>
-#include <linux/tty_driver.h>
-#include <linux/tty_flip.h>
-
-MODULE_DESCRIPTION("DCC TTY Driver");
-MODULE_LICENSE("GPL");
-MODULE_VERSION("1.0");
-
-static spinlock_t g_dcc_tty_lock = SPIN_LOCK_UNLOCKED;
-static struct hrtimer g_dcc_timer;
-static char g_dcc_buffer[16];
-static int g_dcc_buffer_head;
-static int g_dcc_buffer_count;
-static unsigned g_dcc_write_delay_usecs = 1;
-static struct tty_driver *g_dcc_tty_driver;
-static struct tty_struct *g_dcc_tty;
-static int g_dcc_tty_open_count;
-
-static void dcc_poll_locked(void)
-{
- char ch;
- int rch;
- int written;
-
- while (g_dcc_buffer_count) {
- ch = g_dcc_buffer[g_dcc_buffer_head];
- asm(
- "mrc 14, 0, r15, c0, c1, 0\n"
- "mcrcc 14, 0, %1, c0, c5, 0\n"
- "movcc %0, #1\n"
- "movcs %0, #0\n"
- : "=r" (written)
- : "r" (ch)
- );
- if (written) {
- if (ch == '\n')
- g_dcc_buffer[g_dcc_buffer_head] = '\r';
- else {
- g_dcc_buffer_head = (g_dcc_buffer_head + 1) % ARRAY_SIZE(g_dcc_buffer);
- g_dcc_buffer_count--;
- if (g_dcc_tty)
- tty_wakeup(g_dcc_tty);
- }
- g_dcc_write_delay_usecs = 1;
- } else {
- if (g_dcc_write_delay_usecs > 0x100)
- break;
- g_dcc_write_delay_usecs <<= 1;
- udelay(g_dcc_write_delay_usecs);
- }
- }
-
- if (g_dcc_tty && !test_bit(TTY_THROTTLED, &g_dcc_tty->flags)) {
- asm(
- "mrc 14, 0, %0, c0, c1, 0\n"
- "tst %0, #(1 << 30)\n"
- "moveq %0, #-1\n"
- "mrcne 14, 0, %0, c0, c5, 0\n"
- : "=r" (rch)
- );
- if (rch >= 0) {
- ch = rch;
- tty_insert_flip_string(g_dcc_tty, &ch, 1);
- tty_flip_buffer_push(g_dcc_tty);
- }
- }
-
-
- if (g_dcc_buffer_count)
- hrtimer_start(&g_dcc_timer, ktime_set(0, g_dcc_write_delay_usecs * NSEC_PER_USEC), HRTIMER_MODE_REL);
- else
- hrtimer_start(&g_dcc_timer, ktime_set(0, 20 * NSEC_PER_MSEC), HRTIMER_MODE_REL);
-}
-
-static int dcc_tty_open(struct tty_struct * tty, struct file * filp)
-{
- int ret;
- unsigned long irq_flags;
-
- spin_lock_irqsave(&g_dcc_tty_lock, irq_flags);
- if (g_dcc_tty == NULL || g_dcc_tty == tty) {
- g_dcc_tty = tty;
- g_dcc_tty_open_count++;
- ret = 0;
- } else
- ret = -EBUSY;
- spin_unlock_irqrestore(&g_dcc_tty_lock, irq_flags);
-
- printk("dcc_tty_open, tty %p, f_flags %x, returned %d\n", tty, filp->f_flags, ret);
-
- return ret;
-}
-
-static void dcc_tty_close(struct tty_struct * tty, struct file * filp)
-{
- printk("dcc_tty_close, tty %p, f_flags %x\n", tty, filp->f_flags);
- if (g_dcc_tty == tty) {
- if (--g_dcc_tty_open_count == 0)
- g_dcc_tty = NULL;
- }
-}
-
-static int dcc_write(const unsigned char *buf_start, int count)
-{
- const unsigned char *buf = buf_start;
- unsigned long irq_flags;
- int copy_len;
- int space_left;
- int tail;
-
- if (count < 1)
- return 0;
-
- spin_lock_irqsave(&g_dcc_tty_lock, irq_flags);
- do {
- tail = (g_dcc_buffer_head + g_dcc_buffer_count) % ARRAY_SIZE(g_dcc_buffer);
- copy_len = ARRAY_SIZE(g_dcc_buffer) - tail;
- space_left = ARRAY_SIZE(g_dcc_buffer) - g_dcc_buffer_count;
- if (copy_len > space_left)
- copy_len = space_left;
- if (copy_len > count)
- copy_len = count;
- memcpy(&g_dcc_buffer[tail], buf, copy_len);
- g_dcc_buffer_count += copy_len;
- buf += copy_len;
- count -= copy_len;
- if (copy_len < count && copy_len < space_left) {
- space_left -= copy_len;
- copy_len = count;
- if (copy_len > space_left) {
- copy_len = space_left;
- }
- memcpy(g_dcc_buffer, buf, copy_len);
- buf += copy_len;
- count -= copy_len;
- g_dcc_buffer_count += copy_len;
- }
- dcc_poll_locked();
- space_left = ARRAY_SIZE(g_dcc_buffer) - g_dcc_buffer_count;
- } while(count && space_left);
- spin_unlock_irqrestore(&g_dcc_tty_lock, irq_flags);
- return buf - buf_start;
-}
-
-static int dcc_tty_write(struct tty_struct * tty, const unsigned char *buf, int count)
-{
- int ret;
- /* printk("dcc_tty_write %p, %d\n", buf, count); */
- ret = dcc_write(buf, count);
- if (ret != count)
- printk("dcc_tty_write %p, %d, returned %d\n", buf, count, ret);
- return ret;
-}
-
-static int dcc_tty_write_room(struct tty_struct *tty)
-{
- int space_left;
- unsigned long irq_flags;
-
- spin_lock_irqsave(&g_dcc_tty_lock, irq_flags);
- space_left = ARRAY_SIZE(g_dcc_buffer) - g_dcc_buffer_count;
- spin_unlock_irqrestore(&g_dcc_tty_lock, irq_flags);
- return space_left;
-}
-
-static int dcc_tty_chars_in_buffer(struct tty_struct *tty)
-{
- int ret;
- asm(
- "mrc 14, 0, %0, c0, c1, 0\n"
- "mov %0, %0, LSR #30\n"
- "and %0, %0, #1\n"
- : "=r" (ret)
- );
- return ret;
-}
-
-static void dcc_tty_unthrottle(struct tty_struct * tty)
-{
- unsigned long irq_flags;
-
- spin_lock_irqsave(&g_dcc_tty_lock, irq_flags);
- dcc_poll_locked();
- spin_unlock_irqrestore(&g_dcc_tty_lock, irq_flags);
-}
-
-static enum hrtimer_restart dcc_tty_timer_func(struct hrtimer *timer)
-{
- unsigned long irq_flags;
-
- spin_lock_irqsave(&g_dcc_tty_lock, irq_flags);
- dcc_poll_locked();
- spin_unlock_irqrestore(&g_dcc_tty_lock, irq_flags);
- return HRTIMER_NORESTART;
-}
-
-void dcc_console_write(struct console *co, const char *b, unsigned count)
-{
-#if 1
- dcc_write(b, count);
-#else
- /* blocking printk */
- while (count > 0) {
- int written;
- written = dcc_write(b, count);
- if (written) {
- b += written;
- count -= written;
- }
- }
-#endif
-}
-
-static struct tty_driver *dcc_console_device(struct console *c, int *index)
-{
- *index = 0;
- return g_dcc_tty_driver;
-}
-
-static int __init dcc_console_setup(struct console *co, char *options)
-{
- if (co->index != 0)
- return -ENODEV;
- return 0;
-}
-
-
-static struct console dcc_console =
-{
- .name = "ttyDCC",
- .write = dcc_console_write,
- .device = dcc_console_device,
- .setup = dcc_console_setup,
- .flags = CON_PRINTBUFFER,
- .index = -1,
-};
-
-static struct tty_operations dcc_tty_ops = {
- .open = dcc_tty_open,
- .close = dcc_tty_close,
- .write = dcc_tty_write,
- .write_room = dcc_tty_write_room,
- .chars_in_buffer = dcc_tty_chars_in_buffer,
- .unthrottle = dcc_tty_unthrottle,
-};
-
-static int __init dcc_tty_init(void)
-{
- int ret;
-
- hrtimer_init(&g_dcc_timer, CLOCK_MONOTONIC, HRTIMER_MODE_REL);
- g_dcc_timer.function = dcc_tty_timer_func;
-
- g_dcc_tty_driver = alloc_tty_driver(1);
- if (!g_dcc_tty_driver) {
- printk(KERN_ERR "dcc_tty_probe: alloc_tty_driver failed\n");
- ret = -ENOMEM;
- goto err_alloc_tty_driver_failed;
- }
- g_dcc_tty_driver->owner = THIS_MODULE;
- g_dcc_tty_driver->driver_name = "dcc";
- g_dcc_tty_driver->name = "ttyDCC";
- g_dcc_tty_driver->major = 0; // auto assign
- g_dcc_tty_driver->minor_start = 0;
- g_dcc_tty_driver->type = TTY_DRIVER_TYPE_SERIAL;
- g_dcc_tty_driver->subtype = SERIAL_TYPE_NORMAL;
- g_dcc_tty_driver->init_termios = tty_std_termios;
- g_dcc_tty_driver->flags = TTY_DRIVER_RESET_TERMIOS | TTY_DRIVER_REAL_RAW | TTY_DRIVER_DYNAMIC_DEV;
- tty_set_operations(g_dcc_tty_driver, &dcc_tty_ops);
- ret = tty_register_driver(g_dcc_tty_driver);
- if (ret) {
- printk(KERN_ERR "dcc_tty_probe: tty_register_driver failed, %d\n", ret);
- goto err_tty_register_driver_failed;
- }
- tty_register_device(g_dcc_tty_driver, 0, NULL);
-
- register_console(&dcc_console);
- hrtimer_start(&g_dcc_timer, ktime_set(0, 0), HRTIMER_MODE_REL);
-
- return 0;
-
-err_tty_register_driver_failed:
- put_tty_driver(g_dcc_tty_driver);
- g_dcc_tty_driver = NULL;
-err_alloc_tty_driver_failed:
- return ret;
-}
-
-static void __exit dcc_tty_exit(void)
-{
- int ret;
-
- tty_unregister_device(g_dcc_tty_driver, 0);
- ret = tty_unregister_driver(g_dcc_tty_driver);
- if (ret < 0) {
- printk(KERN_ERR "dcc_tty_remove: tty_unregister_driver failed, %d\n", ret);
- } else {
- put_tty_driver(g_dcc_tty_driver);
- }
- g_dcc_tty_driver = NULL;
-}
-
-module_init(dcc_tty_init);
-module_exit(dcc_tty_exit);
-
-
projects / firefly-linux-kernel-4.4.55.git / commitdiff