drivers/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 #ifdef CFG_NS9750_UART
  32
  33 #include "ns9750_bbus.h"        /* for GPIOs */
  34 #include "ns9750_ser.h"         /* for serial configuration */
  35
  36 DECLARE_GLOBAL_DATA_PTR;
  37
  38 #if !defined(CONFIG_CONS_INDEX)
  39 #error "No console index specified."
  40 #endif
  41
  42 #define CONSOLE CONFIG_CONS_INDEX
  43
  44 static unsigned int calcBitrateRegister( void );
  45 static unsigned int calcRxCharGapRegister( void );
  46
  47 static char cCharsAvailable; /* Numbers of chars in unCharCache */
  48 static unsigned int unCharCache; /* unCharCache is only valid if
  49                                   * cCharsAvailable > 0 */
  50
  51 /***********************************************************************
  52  * @Function: serial_init
  53  * @Return: 0
  54  * @Descr: configures GPIOs and UART. Requires BBUS Master Reset turned off
  55  ***********************************************************************/
  56
  57 int serial_init( void )
  58 {
  59         unsigned int aunGPIOTxD[] = { 0, 8, 40, 44 };
  60         unsigned int aunGPIORxD[] = { 1, 9, 41, 45 };
  61
  62         cCharsAvailable = 0;
  63
  64         /* configure TxD and RxD pins for their special function */
  65         set_gpio_cfg_reg_val( aunGPIOTxD[ CONSOLE ],
  66                               NS9750_GPIO_CFG_FUNC_0 | NS9750_GPIO_CFG_OUTPUT );
  67         set_gpio_cfg_reg_val( aunGPIORxD[ CONSOLE ],
  68                               NS9750_GPIO_CFG_FUNC_0 | NS9750_GPIO_CFG_INPUT );
  69
  70         /* configure serial engine */
  71         *get_ser_reg_addr_channel( NS9750_SER_CTRL_A, CONSOLE ) =
  72                 NS9750_SER_CTRL_A_CE |
  73                 NS9750_SER_CTRL_A_STOP |
  74                 NS9750_SER_CTRL_A_WLS_8;
  75
  76         serial_setbrg();
  77
  78         *get_ser_reg_addr_channel( NS9750_SER_CTRL_B, CONSOLE ) =
  79                 NS9750_SER_CTRL_B_RCGT;
  80
  81         return 0;
  82 }
  83
  84 /***********************************************************************
  85  * @Function: serial_putc
  86  * @Return: n/a
  87  * @Descr: writes one character to the FIFO. Blocks until FIFO is not full
  88  ***********************************************************************/
  89
  90 void serial_putc( const char c )
  91 {
  92         if (c == '\n')
  93                 serial_putc( '\r' );
  94
  95         while (!(*get_ser_reg_addr_channel( NS9750_SER_STAT_A, CONSOLE) &
  96                  NS9750_SER_STAT_A_TRDY ) ) {
  97                 /* do nothing, wait for characters in FIFO sent */
  98         }
  99
 100         *(volatile char*) get_ser_reg_addr_channel( NS9750_SER_FIFO,
 101                                                     CONSOLE) = c;
 102 }
 103
 104 /***********************************************************************
 105  * @Function: serial_puts
 106  * @Return: n/a
 107  * @Descr: writes non-zero string to the FIFO.
 108  ***********************************************************************/
 109
 110 void serial_puts( const char *s )
 111 {
 112         while (*s) {
 113                 serial_putc( *s++ );
 114         }
 115 }
 116
 117 /***********************************************************************
 118  * @Function: serial_getc
 119  * @Return: the character read
 120  * @Descr: performs only 8bit accesses to the FIFO. No error handling
 121  ***********************************************************************/
 122
 123 int serial_getc( void )
 124 {
 125         int i;
 126
 127         while (!serial_tstc() ) {
 128                 /* do nothing, wait for incoming characters */
 129         }
 130
 131         /*  at least one character in unCharCache */
 132         i = (int) (unCharCache & 0xff);
 133
 134         unCharCache >>= 8;
 135         cCharsAvailable--;
 136
 137         return i;
 138 }
 139
 140 /***********************************************************************
 141  * @Function: serial_tstc
 142  * @Return: 0 if no input available, otherwise != 0
 143  * @Descr: checks for incoming FIFO not empty. Stores the incoming chars in
 144  *         unCharCache and the numbers of characters in cCharsAvailable
 145  ***********************************************************************/
 146
 147 int serial_tstc( void )
 148 {
 149         unsigned int unRegCache;
 150
 151         if ( cCharsAvailable )
 152                 return 1;
 153
 154         unRegCache = *get_ser_reg_addr_channel( NS9750_SER_STAT_A,CONSOLE );
 155         if( unRegCache & NS9750_SER_STAT_A_RBC ) {
 156                 *get_ser_reg_addr_channel( NS9750_SER_STAT_A, CONSOLE ) =
 157                         NS9750_SER_STAT_A_RBC;
 158                 unRegCache = *get_ser_reg_addr_channel( NS9750_SER_STAT_A,
 159                                                         CONSOLE );
 160         }
 161
 162         if ( unRegCache & NS9750_SER_STAT_A_RRDY ) {
 163                 cCharsAvailable = (unRegCache & NS9750_SER_STAT_A_RXFDB_MA)>>20;
 164                 if ( !cCharsAvailable )
 165                         cCharsAvailable = 4;
 166
 167                 unCharCache = *get_ser_reg_addr_channel( NS9750_SER_FIFO,
 168                                                          CONSOLE );
 169                 return 1;
 170         }
 171
 172         /* no chars available */
 173         return 0;
 174 }
 175
 176 void serial_setbrg( void )
 177 {
 178         *get_ser_reg_addr_channel( NS9750_SER_BITRATE, CONSOLE ) =
 179                 calcBitrateRegister();
 180         *get_ser_reg_addr_channel( NS9750_SER_RX_CHAR_TIMER, CONSOLE ) =
 181                 calcRxCharGapRegister();
 182 }
 183
 184 /***********************************************************************
 185  * @Function: calcBitrateRegister
 186  * @Return: value for the serial bitrate register
 187  * @Descr: register value depends on clock frequency and baudrate
 188  ***********************************************************************/
 189
 190 static unsigned int calcBitrateRegister( void )
 191 {
 192         return ( NS9750_SER_BITRATE_EBIT |
 193                  NS9750_SER_BITRATE_CLKMUX_BCLK |
 194                  NS9750_SER_BITRATE_TMODE |
 195                  NS9750_SER_BITRATE_TCDR_16 |
 196                  NS9750_SER_BITRATE_RCDR_16 |
 197                  ( ( ( ( CONFIG_SYS_CLK_FREQ / 8 ) / /* BBUS clock,[1] Fig. 38 */
 198                        ( gd->baudrate * 16 ) ) - 1 ) &
 199                    NS9750_SER_BITRATE_N_MA ) );
 200 }
 201
 202 /***********************************************************************
 203  * @Function: calcRxCharGapRegister
 204  * @Return: value for the character gap timer register
 205  * @Descr: register value depends on clock frequency and baudrate. Currently 0
 206  *         is used as there is a bug with the gap timer in PLL bypass mode.
 207  ***********************************************************************/
 208
 209 static unsigned int calcRxCharGapRegister( void )
 210 {
 211         return NS9750_SER_RX_CHAR_TIMER_TRUN;
 212 }
 213
 214 #endif /* CFG_NS9750_UART */