drivers/serial/serial_arc.c

   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         writel(arc_console_baud & 0xff, &regs->baudl);
  42         writel((arc_console_baud & 0xff00) >> 8, &regs->baudh);
  43 }
  44
  45 static int arc_serial_init(void)
  46 {
  47         regs = (struct arc_serial_regs *)CONFIG_ARC_UART_BASE;
  48         serial_setbrg();
  49         return 0;
  50 }
  51
  52 static void arc_serial_putc(const char c)
  53 {
  54         if (c == '\n')
  55                 arc_serial_putc('\r');
  56
  57         while (!(readl(&regs->status) & UART_TXEMPTY))
  58                 ;
  59
  60         writel(c, &regs->data);
  61 }
  62
  63 static int arc_serial_tstc(void)
  64 {
  65         return !(readl(&regs->status) & UART_RXEMPTY);
  66 }
  67
  68 static int arc_serial_getc(void)
  69 {
  70         while (!arc_serial_tstc())
  71                 ;
  72
  73         /* Check for overflow errors */
  74         if (readl(&regs->status) & UART_OVERFLOW_ERR)
  75                 return 0;
  76
  77         return readl(&regs->data) & 0xFF;
  78 }
  79
  80 static void arc_serial_puts(const char *s)
  81 {
  82         while (*s)
  83                 arc_serial_putc(*s++);
  84 }
  85
  86 static struct serial_device arc_serial_drv = {
  87         .name   = "arc_serial",
  88         .start  = arc_serial_init,
  89         .stop   = NULL,
  90         .setbrg = arc_serial_setbrg,
  91         .putc   = arc_serial_putc,
  92         .puts   = arc_serial_puts,
  93         .getc   = arc_serial_getc,
  94         .tstc   = arc_serial_tstc,
  95 };
  96
  97 void arc_serial_initialize(void)
  98 {
  99         serial_register(&arc_serial_drv);
 100 }
 101
 102 __weak struct serial_device *default_serial_console(void)
 103 {
 104         return &arc_serial_drv;
 105 }