drivers/serial/ns9750_serial.c

   1 /***********************************************************************
   2  *
   3  * Copyright (C) 2004 by FS Forth-Systeme GmbH.
   4  * All rights reserved.
   5  *
   6  * $Id: ns9750_serial.c,v 1.1 2004/02/16 10:37:20 mpietrek Exp $
   7  * @Author: Markus Pietrek
   8  * @Descr: Serial driver for the NS9750. Only one UART is supported yet.
   9  * @References: [1] NS9750 Hardware Reference/December 2003
  10  * @TODO: Implement Character GAP Timer when chip is fixed for PLL bypass
  11  *
  12  * This program is free software; you can redistribute it and/or
  13  * modify it under the terms of the GNU General Public License as
  14  * published by the Free Software Foundation; either version 2 of
  15  * the License, or (at your option) any later version.
  16  *
  17  * This program is distributed in the hope that it will be useful,
  18  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  19  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  20  * GNU General Public License for more details.
  21  *
  22  * You should have received a copy of the GNU General Public License
  23  * along with this program; if not, write to the Free Software
  24  * Foundation, Inc., 59 Temple Place, Suite 330, Boston,
  25  * MA 02111-1307 USA
  26  *
  27  ***********************************************************************/
  28
  29 #include <common.h>
  30
  31 #include "ns9750_bbus.h"        /* for GPIOs */
  32 #include "ns9750_ser.h"         /* for serial configuration */
  33
  34 DECLARE_GLOBAL_DATA_PTR;
  35
  36 #if !defined(CONFIG_CONS_INDEX)
  37 #error "No console index specified."
  38 #endif
  39
  40 #define CONSOLE CONFIG_CONS_INDEX
  41
  42 static unsigned int calcBitrateRegister( void );
  43 static unsigned int calcRxCharGapRegister( void );
  44
  45 static char cCharsAvailable; /* Numbers of chars in unCharCache */
  46 static unsigned int unCharCache; /* unCharCache is only valid if
  47                                   * cCharsAvailable > 0 */
  48
  49 /***********************************************************************
  50  * @Function: serial_init
  51  * @Return: 0
  52  * @Descr: configures GPIOs and UART. Requires BBUS Master Reset turned off
  53  ***********************************************************************/
  54
  55 int serial_init( void )
  56 {
  57         unsigned int aunGPIOTxD[] = { 0, 8, 40, 44 };
  58         unsigned int aunGPIORxD[] = { 1, 9, 41, 45 };
  59
  60         cCharsAvailable = 0;
  61
  62         /* configure TxD and RxD pins for their special function */
  63         set_gpio_cfg_reg_val( aunGPIOTxD[ CONSOLE ],
  64                               NS9750_GPIO_CFG_FUNC_0 | NS9750_GPIO_CFG_OUTPUT );
  65         set_gpio_cfg_reg_val( aunGPIORxD[ CONSOLE ],
  66                               NS9750_GPIO_CFG_FUNC_0 | NS9750_GPIO_CFG_INPUT );
  67
  68         /* configure serial engine */
  69         *get_ser_reg_addr_channel( NS9750_SER_CTRL_A, CONSOLE ) =
  70                 NS9750_SER_CTRL_A_CE |
  71                 NS9750_SER_CTRL_A_STOP |
  72                 NS9750_SER_CTRL_A_WLS_8;
  73
  74         serial_setbrg();
  75
  76         *get_ser_reg_addr_channel( NS9750_SER_CTRL_B, CONSOLE ) =
  77                 NS9750_SER_CTRL_B_RCGT;
  78
  79         return 0;
  80 }
  81
  82 /***********************************************************************
  83  * @Function: serial_putc
  84  * @Return: n/a
  85  * @Descr: writes one character to the FIFO. Blocks until FIFO is not full
  86  ***********************************************************************/
  87
  88 void serial_putc( const char c )
  89 {
  90         if (c == '\n')
  91                 serial_putc( '\r' );
  92
  93         while (!(*get_ser_reg_addr_channel( NS9750_SER_STAT_A, CONSOLE) &
  94                  NS9750_SER_STAT_A_TRDY ) ) {
  95                 /* do nothing, wait for characters in FIFO sent */
  96         }
  97
  98         *(volatile char*) get_ser_reg_addr_channel( NS9750_SER_FIFO,
  99                                                     CONSOLE) = c;
 100 }
 101
 102 /***********************************************************************
 103  * @Function: serial_puts
 104  * @Return: n/a
 105  * @Descr: writes non-zero string to the FIFO.
 106  ***********************************************************************/
 107
 108 void serial_puts( const char *s )
 109 {
 110         while (*s) {
 111                 serial_putc( *s++ );
 112         }
 113 }
 114
 115 /***********************************************************************
 116  * @Function: serial_getc
 117  * @Return: the character read
 118  * @Descr: performs only 8bit accesses to the FIFO. No error handling
 119  ***********************************************************************/
 120
 121 int serial_getc( void )
 122 {
 123         int i;
 124
 125         while (!serial_tstc() ) {
 126                 /* do nothing, wait for incoming characters */
 127         }
 128
 129         /*  at least one character in unCharCache */
 130         i = (int) (unCharCache & 0xff);
 131
 132         unCharCache >>= 8;
 133         cCharsAvailable--;
 134
 135         return i;
 136 }
 137
 138 /***********************************************************************
 139  * @Function: serial_tstc
 140  * @Return: 0 if no input available, otherwise != 0
 141  * @Descr: checks for incoming FIFO not empty. Stores the incoming chars in
 142  *         unCharCache and the numbers of characters in cCharsAvailable
 143  ***********************************************************************/
 144
 145 int serial_tstc( void )
 146 {
 147         unsigned int unRegCache;
 148
 149         if ( cCharsAvailable )
 150                 return 1;
 151
 152         unRegCache = *get_ser_reg_addr_channel( NS9750_SER_STAT_A,CONSOLE );
 153         if( unRegCache & NS9750_SER_STAT_A_RBC ) {
 154                 *get_ser_reg_addr_channel( NS9750_SER_STAT_A, CONSOLE ) =
 155                         NS9750_SER_STAT_A_RBC;
 156                 unRegCache = *get_ser_reg_addr_channel( NS9750_SER_STAT_A,
 157                                                         CONSOLE );
 158         }
 159
 160         if ( unRegCache & NS9750_SER_STAT_A_RRDY ) {
 161                 cCharsAvailable = (unRegCache & NS9750_SER_STAT_A_RXFDB_MA)>>20;
 162                 if ( !cCharsAvailable )
 163                         cCharsAvailable = 4;
 164
 165                 unCharCache = *get_ser_reg_addr_channel( NS9750_SER_FIFO,
 166                                                          CONSOLE );
 167                 return 1;
 168         }
 169
 170         /* no chars available */
 171         return 0;
 172 }
 173
 174 void serial_setbrg( void )
 175 {
 176         *get_ser_reg_addr_channel( NS9750_SER_BITRATE, CONSOLE ) =
 177                 calcBitrateRegister();
 178         *get_ser_reg_addr_channel( NS9750_SER_RX_CHAR_TIMER, CONSOLE ) =
 179                 calcRxCharGapRegister();
 180 }
 181
 182 /***********************************************************************
 183  * @Function: calcBitrateRegister
 184  * @Return: value for the serial bitrate register
 185  * @Descr: register value depends on clock frequency and baudrate
 186  ***********************************************************************/
 187
 188 static unsigned int calcBitrateRegister( void )
 189 {
 190         return ( NS9750_SER_BITRATE_EBIT |
 191                  NS9750_SER_BITRATE_CLKMUX_BCLK |
 192                  NS9750_SER_BITRATE_TMODE |
 193                  NS9750_SER_BITRATE_TCDR_16 |
 194                  NS9750_SER_BITRATE_RCDR_16 |
 195                  ( ( ( ( CONFIG_SYS_CLK_FREQ / 8 ) / /* BBUS clock,[1] Fig. 38 */
 196                        ( gd->baudrate * 16 ) ) - 1 ) &
 197                    NS9750_SER_BITRATE_N_MA ) );
 198 }
 199
 200 /***********************************************************************
 201  * @Function: calcRxCharGapRegister
 202  * @Return: value for the character gap timer register
 203  * @Descr: register value depends on clock frequency and baudrate. Currently 0
 204  *         is used as there is a bug with the gap timer in PLL bypass mode.
 205  ***********************************************************************/
 206
 207 static unsigned int calcRxCharGapRegister( void )
 208 {
 209         return NS9750_SER_RX_CHAR_TIMER_TRUN;
 210 }