drivers/serial/sandbox.c

   1 /*
   2  * Copyright (c) 2011 The Chromium OS Authors.
   3  *
   4  * SPDX-License-Identifier:     GPL-2.0+
   5  */
   6
   7 /*
   8  * This provide a test serial port. It provides an emulated serial port where
   9  * a test program and read out the serial output and inject serial input for
  10  * U-Boot.
  11  */
  12
  13 #include <common.h>
  14 #include <lcd.h>
  15 #include <os.h>
  16 #include <serial.h>
  17 #include <linux/compiler.h>
  18 #include <asm/state.h>
  19
  20 /*
  21  *
  22  *   serial_buf: A buffer that holds keyboard characters for the
  23  *               Sandbox U-boot.
  24  *
  25  * invariants:
  26  *   serial_buf_write            == serial_buf_read -> empty buffer
  27  *   (serial_buf_write + 1) % 16 == serial_buf_read -> full buffer
  28  */
  29 static char serial_buf[16];
  30 static unsigned int serial_buf_write;
  31 static unsigned int serial_buf_read;
  32
  33 static int sandbox_serial_init(void)
  34 {
  35         struct sandbox_state *state = state_get_current();
  36
  37         if (state->term_raw != STATE_TERM_COOKED)
  38                 os_tty_raw(0, state->term_raw == STATE_TERM_RAW_WITH_SIGS);
  39         return 0;
  40 }
  41
  42 static void sandbox_serial_setbrg(void)
  43 {
  44 }
  45
  46 static void sandbox_serial_putc(const char ch)
  47 {
  48         os_write(1, &ch, 1);
  49 }
  50
  51 static void sandbox_serial_puts(const char *str)
  52 {
  53         os_write(1, str, strlen(str));
  54 }
  55
  56 static unsigned int increment_buffer_index(unsigned int index)
  57 {
  58         return (index + 1) % ARRAY_SIZE(serial_buf);
  59 }
  60
  61 static int sandbox_serial_tstc(void)
  62 {
  63         const unsigned int next_index =
  64                 increment_buffer_index(serial_buf_write);
  65         ssize_t count;
  66
  67         os_usleep(100);
  68 #ifdef CONFIG_LCD
  69         lcd_sync();
  70 #endif
  71         if (next_index == serial_buf_read)
  72                 return 1;       /* buffer full */
  73
  74         count = os_read_no_block(0, &serial_buf[serial_buf_write], 1);
  75         if (count == 1)
  76                 serial_buf_write = next_index;
  77         return serial_buf_write != serial_buf_read;
  78 }
  79
  80 static int sandbox_serial_getc(void)
  81 {
  82         int result;
  83
  84         while (!sandbox_serial_tstc())
  85                 ;       /* buffer empty */
  86
  87         result = serial_buf[serial_buf_read];
  88         serial_buf_read = increment_buffer_index(serial_buf_read);
  89         return result;
  90 }
  91
  92 static struct serial_device sandbox_serial_drv = {
  93         .name   = "sandbox_serial",
  94         .start  = sandbox_serial_init,
  95         .stop   = NULL,
  96         .setbrg = sandbox_serial_setbrg,
  97         .putc   = sandbox_serial_putc,
  98         .puts   = sandbox_serial_puts,
  99         .getc   = sandbox_serial_getc,
 100         .tstc   = sandbox_serial_tstc,
 101 };
 102
 103 void sandbox_serial_initialize(void)
 104 {
 105         serial_register(&sandbox_serial_drv);
 106 }
 107
 108 __weak struct serial_device *default_serial_console(void)
 109 {
 110         return &sandbox_serial_drv;
 111 }