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 <dm.h>
  15 #include <fdtdec.h>
  16 #include <lcd.h>
  17 #include <os.h>
  18 #include <serial.h>
  19 #include <linux/compiler.h>
  20 #include <asm/state.h>
  21
  22 DECLARE_GLOBAL_DATA_PTR;
  23
  24 /*
  25  *
  26  *   serial_buf: A buffer that holds keyboard characters for the
  27  *               Sandbox U-boot.
  28  *
  29  * invariants:
  30  *   serial_buf_write            == serial_buf_read -> empty buffer
  31  *   (serial_buf_write + 1) % 16 == serial_buf_read -> full buffer
  32  */
  33 static char serial_buf[16];
  34 static unsigned int serial_buf_write;
  35 static unsigned int serial_buf_read;
  36
  37 static int sandbox_serial_probe(struct udevice *dev)
  38 {
  39         struct sandbox_state *state = state_get_current();
  40
  41         if (state->term_raw != STATE_TERM_COOKED)
  42                 os_tty_raw(0, state->term_raw == STATE_TERM_RAW_WITH_SIGS);
  43
  44         return 0;
  45 }
  46
  47 static int sandbox_serial_putc(struct udevice *dev, const char ch)
  48 {
  49         os_write(1, &ch, 1);
  50
  51         return 0;
  52 }
  53
  54 static unsigned int increment_buffer_index(unsigned int index)
  55 {
  56         return (index + 1) % ARRAY_SIZE(serial_buf);
  57 }
  58
  59 static int sandbox_serial_pending(struct udevice *dev, bool input)
  60 {
  61         const unsigned int next_index =
  62                 increment_buffer_index(serial_buf_write);
  63         ssize_t count;
  64
  65         if (!input)
  66                 return 0;
  67
  68         os_usleep(100);
  69 #ifdef CONFIG_LCD
  70         lcd_sync();
  71 #endif
  72         if (next_index == serial_buf_read)
  73                 return 1;       /* buffer full */
  74
  75         count = os_read_no_block(0, &serial_buf[serial_buf_write], 1);
  76         if (count == 1)
  77                 serial_buf_write = next_index;
  78
  79         return serial_buf_write != serial_buf_read;
  80 }
  81
  82 static int sandbox_serial_getc(struct udevice *dev)
  83 {
  84         int result;
  85
  86         if (!sandbox_serial_pending(dev, true))
  87                 return -EAGAIN; /* buffer empty */
  88
  89         result = serial_buf[serial_buf_read];
  90         serial_buf_read = increment_buffer_index(serial_buf_read);
  91         return result;
  92 }
  93
  94 static const struct dm_serial_ops sandbox_serial_ops = {
  95         .putc = sandbox_serial_putc,
  96         .pending = sandbox_serial_pending,
  97         .getc = sandbox_serial_getc,
  98 };
  99
 100 static const struct udevice_id sandbox_serial_ids[] = {
 101         { .compatible = "sandbox,serial" },
 102         { }
 103 };
 104
 105 U_BOOT_DRIVER(serial_sandbox) = {
 106         .name   = "serial_sandbox",
 107         .id     = UCLASS_SERIAL,
 108         .of_match = sandbox_serial_ids,
 109         .probe = sandbox_serial_probe,
 110         .ops    = &sandbox_serial_ops,
 111         .flags = DM_FLAG_PRE_RELOC,
 112 };
 113
 114 U_BOOT_DEVICE(serial_sandbox_non_fdt) = {
 115         .name = "serial_sandbox",
 116 };