drivers/serial/serial_ixp.c

   1 /*
   2  * (C) Copyright 2002
   3  * Wolfgang Denk, DENX Software Engineering, <wd@denx.de>
   4  *
   5  * (C) Copyright 2002
   6  * Sysgo Real-Time Solutions, GmbH <www.elinos.com>
   7  * Marius Groeger <mgroeger@sysgo.de>
   8  *
   9  * (C) Copyright 2002
  10  * Sysgo Real-Time Solutions, GmbH <www.elinos.com>
  11  * Alex Zuepke <azu@sysgo.de>
  12  *
  13  * Copyright (C) 1999 2000 2001 Erik Mouw (J.A.K.Mouw@its.tudelft.nl)
  14  *
  15  * SPDX-License-Identifier:     GPL-2.0+
  16  */
  17
  18 #include <common.h>
  19 #include <asm/arch/ixp425.h>
  20 #include <watchdog.h>
  21 #include <serial.h>
  22 #include <linux/compiler.h>
  23
  24 /*
  25  *               14.7456 MHz
  26  * Baud Rate = --------------
  27  *              16 x Divisor
  28  */
  29 #define SERIAL_CLOCK 921600
  30
  31 DECLARE_GLOBAL_DATA_PTR;
  32
  33 static void ixp_serial_setbrg(void)
  34 {
  35         unsigned int quot = 0;
  36         int uart = CONFIG_SYS_IXP425_CONSOLE;
  37
  38         if ((gd->baudrate <= SERIAL_CLOCK) && (SERIAL_CLOCK % gd->baudrate == 0))
  39                 quot = SERIAL_CLOCK / gd->baudrate;
  40         else
  41                 hang ();
  42
  43         IER(uart) = 0;                                  /* Disable for now */
  44         FCR(uart) = 0;                                  /* No fifos enabled */
  45
  46         /* set baud rate */
  47         LCR(uart) = LCR_WLS0 | LCR_WLS1 | LCR_DLAB;
  48         DLL(uart) = quot & 0xff;
  49         DLH(uart) = quot >> 8;
  50         LCR(uart) = LCR_WLS0 | LCR_WLS1;
  51 #ifdef CONFIG_SERIAL_RTS_ACTIVE
  52         MCR(uart) = MCR_RTS;                            /* set RTS active */
  53 #else
  54         MCR(uart) = 0;                                  /* set RTS inactive */
  55 #endif
  56         IER(uart) = IER_UUE;
  57 }
  58
  59 /*
  60  * Initialise the serial port with the given baudrate. The settings
  61  * are always 8 data bits, no parity, 1 stop bit, no start bits.
  62  *
  63  */
  64 static int ixp_serial_init(void)
  65 {
  66         serial_setbrg ();
  67
  68         return (0);
  69 }
  70
  71
  72 /*
  73  * Output a single byte to the serial port.
  74  */
  75 static void ixp_serial_putc(const char c)
  76 {
  77         /* wait for room in the tx FIFO on UART */
  78         while ((LSR(CONFIG_SYS_IXP425_CONSOLE) & LSR_TEMT) == 0)
  79                 WATCHDOG_RESET();       /* Reset HW Watchdog, if needed */
  80
  81         THR(CONFIG_SYS_IXP425_CONSOLE) = c;
  82
  83         /* If \n, also do \r */
  84         if (c == '\n')
  85                 serial_putc ('\r');
  86 }
  87
  88 /*
  89  * Read a single byte from the serial port. Returns 1 on success, 0
  90  * otherwise. When the function is succesfull, the character read is
  91  * written into its argument c.
  92  */
  93 static int ixp_serial_tstc(void)
  94 {
  95         return LSR(CONFIG_SYS_IXP425_CONSOLE) & LSR_DR;
  96 }
  97
  98 /*
  99  * Read a single byte from the serial port. Returns 1 on success, 0
 100  * otherwise. When the function is succesfull, the character read is
 101  * written into its argument c.
 102  */
 103 static int ixp_serial_getc(void)
 104 {
 105         while (!(LSR(CONFIG_SYS_IXP425_CONSOLE) & LSR_DR))
 106                 WATCHDOG_RESET();       /* Reset HW Watchdog, if needed */
 107
 108         return (char) RBR(CONFIG_SYS_IXP425_CONSOLE) & 0xff;
 109 }
 110
 111 static struct serial_device ixp_serial_drv = {
 112         .name   = "ixp_serial",
 113         .start  = ixp_serial_init,
 114         .stop   = NULL,
 115         .setbrg = ixp_serial_setbrg,
 116         .putc   = ixp_serial_putc,
 117         .puts   = default_serial_puts,
 118         .getc   = ixp_serial_getc,
 119         .tstc   = ixp_serial_tstc,
 120 };
 121
 122 void ixp_serial_initialize(void)
 123 {
 124         serial_register(&ixp_serial_drv);
 125 }
 126
 127 __weak struct serial_device *default_serial_console(void)
 128 {
 129         return &ixp_serial_drv;
 130 }