1 /* 2 * Copyright (C) 2013 Synopsys, Inc. (www.synopsys.com) 3 * 4 * This program is free software; you can redistribute it and/or modify 5 * it under the terms of the GNU General Public License version 2 as 6 * published by the Free Software Foundation. 7 * 8 */ 9 10 #include <common.h> 11 #include <serial.h> 12 13 DECLARE_GLOBAL_DATA_PTR; 14 15 struct arc_serial_regs { 16 unsigned int id0; 17 unsigned int id1; 18 unsigned int id2; 19 unsigned int id3; 20 unsigned int data; 21 unsigned int status; 22 unsigned int baudl; 23 unsigned int baudh; 24 }; 25 26 /* Bit definitions of STATUS register */ 27 #define UART_RXEMPTY (1 << 5) 28 #define UART_OVERFLOW_ERR (1 << 1) 29 #define UART_TXEMPTY (1 << 7) 30 31 struct arc_serial_regs *regs; 32 33 static void arc_serial_setbrg(void) 34 { 35 int arc_console_baud; 36 37 if (!gd->baudrate) 38 gd->baudrate = CONFIG_BAUDRATE; 39 40 arc_console_baud = gd->cpu_clk / (gd->baudrate * 4) - 1; 41 writeb(arc_console_baud & 0xff, ®s->baudl); 42 43 #ifdef CONFIG_ARC 44 /* 45 * UART ISS(Instruction Set simulator) emulation has a subtle bug: 46 * A existing value of Baudh = 0 is used as a indication to startup 47 * it's internal state machine. 48 * Thus if baudh is set to 0, 2 times, it chokes. 49 * This happens with BAUD=115200 and the formaula above 50 * Until that is fixed, when running on ISS, we will set baudh to !0 51 */ 52 if (gd->arch.running_on_hw) 53 writeb((arc_console_baud & 0xff00) >> 8, ®s->baudh); 54 else 55 writeb(1, ®s->baudh); 56 #else 57 writeb((arc_console_baud & 0xff00) >> 8, ®s->baudh); 58 #endif 59 } 60 61 static int arc_serial_init(void) 62 { 63 regs = (struct arc_serial_regs *)CONFIG_ARC_UART_BASE; 64 serial_setbrg(); 65 return 0; 66 } 67 68 static void arc_serial_putc(const char c) 69 { 70 if (c == '\n') 71 arc_serial_putc('\r'); 72 73 while (!(readb(®s->status) & UART_TXEMPTY)) 74 ; 75 76 writeb(c, ®s->data); 77 } 78 79 static int arc_serial_tstc(void) 80 { 81 return !(readb(®s->status) & UART_RXEMPTY); 82 } 83 84 static int arc_serial_getc(void) 85 { 86 while (!arc_serial_tstc()) 87 ; 88 89 /* Check for overflow errors */ 90 if (readb(®s->status) & UART_OVERFLOW_ERR) 91 return 0; 92 93 return readb(®s->data) & 0xFF; 94 } 95 96 static struct serial_device arc_serial_drv = { 97 .name = "arc_serial", 98 .start = arc_serial_init, 99 .stop = NULL, 100 .setbrg = arc_serial_setbrg, 101 .putc = arc_serial_putc, 102 .puts = default_serial_puts, 103 .getc = arc_serial_getc, 104 .tstc = arc_serial_tstc, 105 }; 106 107 void arc_serial_initialize(void) 108 { 109 serial_register(&arc_serial_drv); 110 } 111 112 __weak struct serial_device *default_serial_console(void) 113 { 114 return &arc_serial_drv; 115 } 116