drivers/serial/sandbox.c

   1 /*
   2  * Copyright (c) 2011 The Chromium OS Authors.
   3  * See file CREDITS for list of people who contributed to this
   4  * project.
   5  *
   6  * This program is free software; you can redistribute it and/or
   7  * modify it under the terms of the GNU General Public License as
   8  * published by the Free Software Foundation; either version 2 of
   9  * the License, or (at your option) any later version.
  10  *
  11  * This program is distributed in the hope that it will be useful,
  12  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  13  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
  14  * GNU General Public License for more details.
  15  *
  16  * You should have received a copy of the GNU General Public License
  17  * along with this program; if not, write to the Free Software
  18  * Foundation, Inc., 59 Temple Place, Suite 330, Boston,
  19  * MA 02111-1307 USA
  20  */
  21
  22 /*
  23  * This provide a test serial port. It provides an emulated serial port where
  24  * a test program and read out the serial output and inject serial input for
  25  * U-Boot.
  26  */
  27
  28 #include <common.h>
  29 #include <os.h>
  30 #include <serial.h>
  31 #include <linux/compiler.h>
  32
  33 /*
  34  *
  35  *   serial_buf: A buffer that holds keyboard characters for the
  36  *               Sandbox U-boot.
  37  *
  38  * invariants:
  39  *   serial_buf_write            == serial_buf_read -> empty buffer
  40  *   (serial_buf_write + 1) % 16 == serial_buf_read -> full buffer
  41  */
  42 static char serial_buf[16];
  43 static unsigned int serial_buf_write;
  44 static unsigned int serial_buf_read;
  45
  46 static int sandbox_serial_init(void)
  47 {
  48         os_tty_raw(0);
  49         return 0;
  50 }
  51
  52 static void sandbox_serial_setbrg(void)
  53 {
  54 }
  55
  56 static void sandbox_serial_putc(const char ch)
  57 {
  58         os_write(1, &ch, 1);
  59 }
  60
  61 static void sandbox_serial_puts(const char *str)
  62 {
  63         os_write(1, str, strlen(str));
  64 }
  65
  66 static unsigned int increment_buffer_index(unsigned int index)
  67 {
  68         return (index + 1) % ARRAY_SIZE(serial_buf);
  69 }
  70
  71 static int sandbox_serial_tstc(void)
  72 {
  73         const unsigned int next_index =
  74                 increment_buffer_index(serial_buf_write);
  75         ssize_t count;
  76
  77         os_usleep(100);
  78         if (next_index == serial_buf_read)
  79                 return 1;       /* buffer full */
  80
  81         count = os_read_no_block(0, &serial_buf[serial_buf_write], 1);
  82         if (count == 1)
  83                 serial_buf_write = next_index;
  84         return serial_buf_write != serial_buf_read;
  85 }
  86
  87 static int sandbox_serial_getc(void)
  88 {
  89         int result;
  90
  91         while (!sandbox_serial_tstc())
  92                 ;       /* buffer empty */
  93
  94         result = serial_buf[serial_buf_read];
  95         serial_buf_read = increment_buffer_index(serial_buf_read);
  96         return result;
  97 }
  98
  99 static struct serial_device sandbox_serial_drv = {
 100         .name   = "sandbox_serial",
 101         .start  = sandbox_serial_init,
 102         .stop   = NULL,
 103         .setbrg = sandbox_serial_setbrg,
 104         .putc   = sandbox_serial_putc,
 105         .puts   = sandbox_serial_puts,
 106         .getc   = sandbox_serial_getc,
 107         .tstc   = sandbox_serial_tstc,
 108 };
 109
 110 void sandbox_serial_initialize(void)
 111 {
 112         serial_register(&sandbox_serial_drv);
 113 }
 114
 115 __weak struct serial_device *default_serial_console(void)
 116 {
 117         return &sandbox_serial_drv;
 118 }