Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1 | /* |
| 2 | * arch/v850/kernel/memcons.c -- Console I/O to a memory buffer |
| 3 | * |
| 4 | * Copyright (C) 2001,02 NEC Corporation |
| 5 | * Copyright (C) 2001,02 Miles Bader <miles@gnu.org> |
| 6 | * |
| 7 | * This file is subject to the terms and conditions of the GNU General |
| 8 | * Public License. See the file COPYING in the main directory of this |
| 9 | * archive for more details. |
| 10 | * |
| 11 | * Written by Miles Bader <miles@gnu.org> |
| 12 | */ |
| 13 | |
| 14 | #include <linux/kernel.h> |
| 15 | #include <linux/console.h> |
| 16 | #include <linux/tty.h> |
| 17 | #include <linux/tty_driver.h> |
| 18 | #include <linux/init.h> |
| 19 | |
| 20 | /* If this device is enabled, the linker map should define start and |
| 21 | end points for its buffer. */ |
| 22 | extern char memcons_output[], memcons_output_end; |
| 23 | |
| 24 | /* Current offset into the buffer. */ |
| 25 | static unsigned long memcons_offs = 0; |
| 26 | |
| 27 | /* Spinlock protecting memcons_offs. */ |
| 28 | static DEFINE_SPINLOCK(memcons_lock); |
| 29 | |
| 30 | |
| 31 | static size_t write (const char *buf, size_t len) |
| 32 | { |
| 33 | int flags; |
| 34 | char *point; |
| 35 | |
| 36 | spin_lock_irqsave (memcons_lock, flags); |
| 37 | |
| 38 | point = memcons_output + memcons_offs; |
| 39 | if (point + len >= &memcons_output_end) { |
| 40 | len = &memcons_output_end - point; |
| 41 | memcons_offs = 0; |
| 42 | } else |
| 43 | memcons_offs += len; |
| 44 | |
| 45 | spin_unlock_irqrestore (memcons_lock, flags); |
| 46 | |
| 47 | memcpy (point, buf, len); |
| 48 | |
| 49 | return len; |
| 50 | } |
| 51 | |
| 52 | |
| 53 | /* Low-level console. */ |
| 54 | |
| 55 | static void memcons_write (struct console *co, const char *buf, unsigned len) |
| 56 | { |
| 57 | while (len > 0) |
| 58 | len -= write (buf, len); |
| 59 | } |
| 60 | |
| 61 | static struct tty_driver *tty_driver; |
| 62 | |
| 63 | static struct tty_driver *memcons_device (struct console *co, int *index) |
| 64 | { |
| 65 | *index = co->index; |
| 66 | return tty_driver; |
| 67 | } |
| 68 | |
| 69 | static struct console memcons = |
| 70 | { |
| 71 | .name = "memcons", |
| 72 | .write = memcons_write, |
| 73 | .device = memcons_device, |
| 74 | .flags = CON_PRINTBUFFER, |
| 75 | .index = -1, |
| 76 | }; |
| 77 | |
| 78 | void memcons_setup (void) |
| 79 | { |
| 80 | register_console (&memcons); |
| 81 | printk (KERN_INFO "Console: static memory buffer (memcons)\n"); |
| 82 | } |
| 83 | |
| 84 | /* Higher level TTY interface. */ |
| 85 | |
| 86 | int memcons_tty_open (struct tty_struct *tty, struct file *filp) |
| 87 | { |
| 88 | return 0; |
| 89 | } |
| 90 | |
| 91 | int memcons_tty_write (struct tty_struct *tty, const unsigned char *buf, int len) |
| 92 | { |
| 93 | return write (buf, len); |
| 94 | } |
| 95 | |
| 96 | int memcons_tty_write_room (struct tty_struct *tty) |
| 97 | { |
| 98 | return &memcons_output_end - (memcons_output + memcons_offs); |
| 99 | } |
| 100 | |
| 101 | int memcons_tty_chars_in_buffer (struct tty_struct *tty) |
| 102 | { |
| 103 | /* We have no buffer. */ |
| 104 | return 0; |
| 105 | } |
| 106 | |
| 107 | static struct tty_operations ops = { |
| 108 | .open = memcons_tty_open, |
| 109 | .write = memcons_tty_write, |
| 110 | .write_room = memcons_tty_write_room, |
| 111 | .chars_in_buffer = memcons_tty_chars_in_buffer, |
| 112 | }; |
| 113 | |
| 114 | int __init memcons_tty_init (void) |
| 115 | { |
| 116 | int err; |
| 117 | struct tty_driver *driver = alloc_tty_driver(1); |
| 118 | if (!driver) |
| 119 | return -ENOMEM; |
| 120 | |
| 121 | driver->name = "memcons"; |
| 122 | driver->major = TTY_MAJOR; |
| 123 | driver->minor_start = 64; |
| 124 | driver->type = TTY_DRIVER_TYPE_SYSCONS; |
| 125 | driver->init_termios = tty_std_termios; |
| 126 | tty_set_operations(driver, &ops); |
| 127 | err = tty_register_driver(driver); |
| 128 | if (err) { |
| 129 | put_tty_driver(driver); |
| 130 | return err; |
| 131 | } |
| 132 | tty_driver = driver; |
| 133 | return 0; |
| 134 | } |
| 135 | __initcall (memcons_tty_init); |