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 19 /* 20 * 21 * serial_buf: A buffer that holds keyboard characters for the 22 * Sandbox U-boot. 23 * 24 * invariants: 25 * serial_buf_write == serial_buf_read -> empty buffer 26 * (serial_buf_write + 1) % 16 == serial_buf_read -> full buffer 27 */ 28 static char serial_buf[16]; 29 static unsigned int serial_buf_write; 30 static unsigned int serial_buf_read; 31 32 static int sandbox_serial_init(void) 33 { 34 os_tty_raw(0); 35 return 0; 36 } 37 38 static void sandbox_serial_setbrg(void) 39 { 40 } 41 42 static void sandbox_serial_putc(const char ch) 43 { 44 os_write(1, &ch, 1); 45 } 46 47 static void sandbox_serial_puts(const char *str) 48 { 49 os_write(1, str, strlen(str)); 50 } 51 52 static unsigned int increment_buffer_index(unsigned int index) 53 { 54 return (index + 1) % ARRAY_SIZE(serial_buf); 55 } 56 57 static int sandbox_serial_tstc(void) 58 { 59 const unsigned int next_index = 60 increment_buffer_index(serial_buf_write); 61 ssize_t count; 62 63 os_usleep(100); 64 #ifdef CONFIG_LCD 65 lcd_sync(); 66 #endif 67 if (next_index == serial_buf_read) 68 return 1; /* buffer full */ 69 70 count = os_read_no_block(0, &serial_buf[serial_buf_write], 1); 71 if (count == 1) 72 serial_buf_write = next_index; 73 return serial_buf_write != serial_buf_read; 74 } 75 76 static int sandbox_serial_getc(void) 77 { 78 int result; 79 80 while (!sandbox_serial_tstc()) 81 ; /* buffer empty */ 82 83 result = serial_buf[serial_buf_read]; 84 serial_buf_read = increment_buffer_index(serial_buf_read); 85 return result; 86 } 87 88 static struct serial_device sandbox_serial_drv = { 89 .name = "sandbox_serial", 90 .start = sandbox_serial_init, 91 .stop = NULL, 92 .setbrg = sandbox_serial_setbrg, 93 .putc = sandbox_serial_putc, 94 .puts = sandbox_serial_puts, 95 .getc = sandbox_serial_getc, 96 .tstc = sandbox_serial_tstc, 97 }; 98 99 void sandbox_serial_initialize(void) 100 { 101 serial_register(&sandbox_serial_drv); 102 } 103 104 __weak struct serial_device *default_serial_console(void) 105 { 106 return &sandbox_serial_drv; 107 } 108