LXR uboot/drivers/serial/s3c64xx.c

   1/*
   2 * (C) Copyright 2002
   3 * Gary Jennejohn, DENX Software Engineering, <garyj@denx.de>
   4 *
   5 * (C) Copyright 2008
   6 * Guennadi Liakhovetki, DENX Software Engineering, <lg@denx.de>
   7 *
   8 * This program is free software; you can redistribute it and/or modify
   9 * it under the terms of the GNU General Public License as published by
  10 * the Free Software Foundation; either version 2 of the License, or
  11 * (at your option) any later version.
  12 *
  13 * This program is distributed in the hope that it will be useful,
  14 * but WITHOUT ANY WARRANTY; without even the implied warranty of
  15 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  16 * GNU General Public License for more details.
  17 *
  18 * You should have received a copy of the GNU General Public License
  19 * along with this program; if not, write to the Free Software
  20 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
  21 *
  22 */
  23
  24#include <common.h>
  25
  26#include <asm/arch/s3c6400.h>
  27
  28DECLARE_GLOBAL_DATA_PTR;
  29
  30#ifdef CONFIG_SERIAL1
  31#define UART_NR S3C64XX_UART0
  32
  33#elif defined(CONFIG_SERIAL2)
  34#define UART_NR S3C64XX_UART1
  35
  36#elif defined(CONFIG_SERIAL3)
  37#define UART_NR S3C64XX_UART2
  38
  39#else
  40#error "Bad: you didn't configure serial ..."
  41#endif
  42
  43#define barrier() asm volatile("" ::: "memory")
  44
  45/*
  46 * The coefficient, used to calculate the baudrate on S3C6400 UARTs is
  47 * calculated as
  48 * C = UBRDIV * 16 + number_of_set_bits_in_UDIVSLOT
  49 * however, section 31.6.11 of the datasheet doesn't recomment using 1 for 1,
  50 * 3 for 2, ... (2^n - 1) for n, instead, they suggest using these constants:
  51 */
  52static const int udivslot[] = {
  53        0,
  54        0x0080,
  55        0x0808,
  56        0x0888,
  57        0x2222,
  58        0x4924,
  59        0x4a52,
  60        0x54aa,
  61        0x5555,
  62        0xd555,
  63        0xd5d5,
  64        0xddd5,
  65        0xdddd,
  66        0xdfdd,
  67        0xdfdf,
  68        0xffdf,
  69};
  70
  71void serial_setbrg(void)
  72{
  73        s3c64xx_uart *const uart = s3c64xx_get_base_uart(UART_NR);
  74        u32 pclk = get_PCLK();
  75        u32 baudrate = gd->baudrate;
  76        int i;
  77
  78        i = (pclk / baudrate) % 16;
  79
  80        uart->UBRDIV = pclk / baudrate / 16 - 1;
  81        uart->UDIVSLOT = udivslot[i];
  82
  83        for (i = 0; i < 100; i++)
  84                barrier();
  85}
  86
  87/*
  88 * Initialise the serial port with the given baudrate. The settings
  89 * are always 8 data bits, no parity, 1 stop bit, no start bits.
  90 */
  91int serial_init(void)
  92{
  93        s3c64xx_uart *const uart = s3c64xx_get_base_uart(UART_NR);
  94
  95        /* reset and enable FIFOs, set triggers to the maximum */
  96        uart->UFCON = 0xff;
  97        uart->UMCON = 0;
  98        /* 8N1 */
  99        uart->ULCON = 3;
 100        /* No interrupts, no DMA, pure polling */
 101        uart->UCON = 5;
 102
 103        serial_setbrg();
 104
 105        return 0;
 106}
 107
 108/*
 109 * Read a single byte from the serial port. Returns 1 on success, 0
 110 * otherwise. When the function is succesfull, the character read is
 111 * written into its argument c.
 112 */
 113int serial_getc(void)
 114{
 115        s3c64xx_uart *const uart = s3c64xx_get_base_uart(UART_NR);
 116
 117        /* wait for character to arrive */
 118        while (!(uart->UTRSTAT & 0x1));
 119
 120        return uart->URXH & 0xff;
 121}
 122
 123#ifdef CONFIG_MODEM_SUPPORT
 124static int be_quiet;
 125void disable_putc(void)
 126{
 127        be_quiet = 1;
 128}
 129
 130void enable_putc(void)
 131{
 132        be_quiet = 0;
 133}
 134#endif
 135
 136
 137/*
 138 * Output a single byte to the serial port.
 139 */
 140void serial_putc(const char c)
 141{
 142        s3c64xx_uart *const uart = s3c64xx_get_base_uart(UART_NR);
 143
 144#ifdef CONFIG_MODEM_SUPPORT
 145        if (be_quiet)
 146                return;
 147#endif
 148
 149        /* wait for room in the tx FIFO */
 150        while (!(uart->UTRSTAT & 0x2));
 151
 152        uart->UTXH = c;
 153
 154        /* If \n, also do \r */
 155        if (c == '\n')
 156                serial_putc('\r');
 157}
 158
 159/*
 160 * Test whether a character is in the RX buffer
 161 */
 162int serial_tstc(void)
 163{
 164        s3c64xx_uart *const uart = s3c64xx_get_base_uart(UART_NR);
 165
 166        return uart->UTRSTAT & 0x1;
 167}
 168
 169void serial_puts(const char *s)
 170{
 171        while (*s)
 172                serial_putc(*s++);
 173}
 174