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