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 <os.h> 15 #include <serial.h> 16 #include <linux/compiler.h> 17 18 /* 19 * 20 * serial_buf: A buffer that holds keyboard characters for the 21 * Sandbox U-boot. 22 * 23 * invariants: 24 * serial_buf_write == serial_buf_read -> empty buffer 25 * (serial_buf_write + 1) % 16 == serial_buf_read -> full buffer 26 */ 27 static char serial_buf[16]; 28 static unsigned int serial_buf_write; 29 static unsigned int serial_buf_read; 30 31 static int sandbox_serial_init(void) 32 { 33 os_tty_raw(0); 34 return 0; 35 } 36 37 static void sandbox_serial_setbrg(void) 38 { 39 } 40 41 static void sandbox_serial_putc(const char ch) 42 { 43 os_write(1, &ch, 1); 44 } 45 46 static void sandbox_serial_puts(const char *str) 47 { 48 os_write(1, str, strlen(str)); 49 } 50 51 static unsigned int increment_buffer_index(unsigned int index) 52 { 53 return (index + 1) % ARRAY_SIZE(serial_buf); 54 } 55 56 static int sandbox_serial_tstc(void) 57 { 58 const unsigned int next_index = 59 increment_buffer_index(serial_buf_write); 60 ssize_t count; 61 62 os_usleep(100); 63 if (next_index == serial_buf_read) 64 return 1; /* buffer full */ 65 66 count = os_read_no_block(0, &serial_buf[serial_buf_write], 1); 67 if (count == 1) 68 serial_buf_write = next_index; 69 return serial_buf_write != serial_buf_read; 70 } 71 72 static int sandbox_serial_getc(void) 73 { 74 int result; 75 76 while (!sandbox_serial_tstc()) 77 ; /* buffer empty */ 78 79 result = serial_buf[serial_buf_read]; 80 serial_buf_read = increment_buffer_index(serial_buf_read); 81 return result; 82 } 83 84 static struct serial_device sandbox_serial_drv = { 85 .name = "sandbox_serial", 86 .start = sandbox_serial_init, 87 .stop = NULL, 88 .setbrg = sandbox_serial_setbrg, 89 .putc = sandbox_serial_putc, 90 .puts = sandbox_serial_puts, 91 .getc = sandbox_serial_getc, 92 .tstc = sandbox_serial_tstc, 93 }; 94 95 void sandbox_serial_initialize(void) 96 { 97 serial_register(&sandbox_serial_drv); 98 } 99 100 __weak struct serial_device *default_serial_console(void) 101 { 102 return &sandbox_serial_drv; 103 } 104