drivers/serial_max3100.c

   1 /*
   2  * (C) Copyright 2003
   3  *
   4  * Pantelis Antoniou <panto@intracom.gr>
   5  * Intracom S.A.
   6  *
   7  * See file CREDITS for list of people who contributed to this
   8  * project.
   9  *
  10  * This program is free software; you can redistribute it and/or
  11  * modify it under the terms of the GNU General Public License as
  12  * published by the Free Software Foundation; either version 2 of
  13  * the License, or (at your option) any later version.
  14  *
  15  * This program is distributed in the hope that it will be useful,
  16  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  17  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  18  * GNU General Public License for more details.
  19  *
  20  * You should have received a copy of the GNU General Public License
  21  * along with this program; if not, write to the Free Software
  22  * Foundation, Inc., 59 Temple Place, Suite 330, Boston,
  23  * MA 02111-1307 USA
  24  */
  25
  26 #include <common.h>
  27 #include <watchdog.h>
  28
  29 #ifdef CONFIG_MAX3100_SERIAL
  30
  31 /**************************************************************/
  32
  33 /* convienient macros */
  34 #define MAX3100_SPI_RXD() (MAX3100_SPI_RXD_PORT & MAX3100_SPI_RXD_BIT)
  35
  36 #define MAX3100_SPI_TXD(x) \
  37         do { \
  38                 if (x) \
  39                         MAX3100_SPI_TXD_PORT |=  MAX3100_SPI_TXD_BIT; \
  40                 else \
  41                         MAX3100_SPI_TXD_PORT &= ~MAX3100_SPI_TXD_BIT; \
  42         } while(0)
  43
  44 #define MAX3100_SPI_CLK(x) \
  45         do { \
  46                 if (x) \
  47                         MAX3100_SPI_CLK_PORT |=  MAX3100_SPI_CLK_BIT; \
  48                 else \
  49                         MAX3100_SPI_CLK_PORT &= ~MAX3100_SPI_CLK_BIT; \
  50         } while(0)
  51
  52 #define MAX3100_SPI_CLK_TOGGLE() (MAX3100_SPI_CLK_PORT ^= MAX3100_SPI_CLK_BIT)
  53
  54 #define MAX3100_CS(x) \
  55         do { \
  56                 if (x) \
  57                         MAX3100_CS_PORT |=  MAX3100_CS_BIT; \
  58                 else \
  59                         MAX3100_CS_PORT &= ~MAX3100_CS_BIT; \
  60         } while(0)
  61
  62 /**************************************************************/
  63
  64 /* MAX3100 definitions */
  65
  66 #define MAX3100_WC      (3 << 14)               /* write configuration */
  67 #define MAX3100_RC      (1 << 14)               /* read  configuration */
  68 #define MAX3100_WD      (2 << 14)               /* write data          */
  69 #define MAX3100_RD      (0 << 14)               /* read  data          */
  70
  71 /* configuration register bits */
  72 #define MAX3100_FEN     (1 << 13)               /* FIFO enable           */
  73 #define MAX3100_SHDN    (1 << 12)               /* shutdown bit          */
  74 #define MAX3100_TM      (1 << 11)               /* T bit irq mask        */
  75 #define MAX3100_RM      (1 << 10)               /* R bit irq mask        */
  76 #define MAX3100_PM      (1 <<  9)               /* P bit irq mask        */
  77 #define MAX3100_RAM     (1 <<  8)               /* mask for RA/FE bit    */
  78 #define MAX3100_IR      (1 <<  7)               /* IRDA timing mode      */
  79 #define MAX3100_ST      (1 <<  6)               /* transmit stop bit     */
  80 #define MAX3100_PE      (1 <<  5)               /* parity enable bit     */
  81 #define MAX3100_L       (1 <<  4)               /* Length bit            */
  82 #define MAX3100_B_MASK  (0x000F)                /* baud rate bits mask   */
  83 #define MAX3100_B(x)    ((x) & 0x000F)  /* baud rate select bits */
  84
  85 /* data register bits (write) */
  86 #define MAX3100_TE      (1 << 10)               /* transmit enable bit (active low)        */
  87 #define MAX3100_RTS     (1 <<  9)               /* request-to-send bit (inverted ~RTS pin) */
  88
  89 /* data register bits (read) */
  90 #define MAX3100_RA      (1 << 10)               /* receiver activity when in shutdown mode */
  91 #define MAX3100_FE      (1 << 10)               /* framing error when in normal mode       */
  92 #define MAX3100_CTS     (1 <<  9)               /* clear-to-send bit (inverted ~CTS pin)   */
  93
  94 /* data register bits (both directions) */
  95 #define MAX3100_R       (1 << 15)               /* receive bit    */
  96 #define MAX3100_T       (1 << 14)               /* transmit bit   */
  97 #define MAX3100_P       (1 <<  8)               /* parity bit     */
  98 #define MAX3100_D_MASK  0x00FF                  /* data bits mask */
  99 #define MAX3100_D(x)    ((x) & 0x00FF)          /* data bits      */
 100
 101 /* these definitions are valid only for fOSC = 3.6864MHz */
 102 #define MAX3100_B_230400        MAX3100_B(0)
 103 #define MAX3100_B_115200        MAX3100_B(1)
 104 #define MAX3100_B_57600         MAX3100_B(2)
 105 #define MAX3100_B_38400         MAX3100_B(9)
 106 #define MAX3100_B_19200         MAX3100_B(10)
 107 #define MAX3100_B_9600          MAX3100_B(11)
 108 #define MAX3100_B_4800          MAX3100_B(12)
 109 #define MAX3100_B_2400          MAX3100_B(13)
 110 #define MAX3100_B_1200          MAX3100_B(14)
 111 #define MAX3100_B_600           MAX3100_B(15)
 112
 113 /**************************************************************/
 114
 115 static inline unsigned int max3100_transfer(unsigned int val)
 116 {
 117         unsigned int rx;
 118         int b;
 119
 120         MAX3100_SPI_CLK(0);
 121         MAX3100_CS(0);
 122
 123         rx = 0; b = 16;
 124         while (--b >= 0) {
 125                 MAX3100_SPI_TXD(val & 0x8000);
 126                 val <<= 1;
 127                 MAX3100_SPI_CLK_TOGGLE();
 128                 udelay(1);
 129                 rx <<= 1;
 130                 if (MAX3100_SPI_RXD())
 131                         rx |= 1;
 132                 MAX3100_SPI_CLK_TOGGLE();
 133                 udelay(1);
 134         }
 135
 136         MAX3100_SPI_CLK(1);
 137         MAX3100_CS(1);
 138
 139         return rx;
 140 }
 141
 142 /**************************************************************/
 143
 144 /* must be power of 2 */
 145 #define RXFIFO_SZ       16
 146
 147 static int rxfifo_cnt;
 148 static int rxfifo_in;
 149 static int rxfifo_out;
 150 static unsigned char rxfifo_buf[16];
 151
 152 static void max3100_putc(int c)
 153 {
 154         unsigned int rx;
 155
 156         while (((rx = max3100_transfer(MAX3100_RC)) & MAX3100_T) == 0)
 157                 WATCHDOG_RESET();
 158
 159         rx = max3100_transfer(MAX3100_WD | (c & 0xff));
 160         if ((rx & MAX3100_RD) != 0 && rxfifo_cnt < RXFIFO_SZ) {
 161                 rxfifo_cnt++;
 162                 rxfifo_buf[rxfifo_in++] = rx & 0xff;
 163                 rxfifo_in &= RXFIFO_SZ - 1;
 164         }
 165 }
 166
 167 static int max3100_getc(void)
 168 {
 169         int c;
 170         unsigned int rx;
 171
 172         while (rxfifo_cnt == 0) {
 173                 rx = max3100_transfer(MAX3100_RD);
 174                 if ((rx & MAX3100_R) != 0) {
 175                         do {
 176                                 rxfifo_cnt++;
 177                                 rxfifo_buf[rxfifo_in++] = rx & 0xff;
 178                                 rxfifo_in &= RXFIFO_SZ - 1;
 179
 180                                 if (rxfifo_cnt >= RXFIFO_SZ)
 181                                         break;
 182                         } while (((rx = max3100_transfer(MAX3100_RD)) & MAX3100_R) != 0);
 183                 }
 184                 WATCHDOG_RESET();
 185         }
 186
 187         rxfifo_cnt--;
 188         c = rxfifo_buf[rxfifo_out++];
 189         rxfifo_out &= RXFIFO_SZ - 1;
 190         return c;
 191 }
 192
 193 static int max3100_tstc(void)
 194 {
 195         unsigned int rx;
 196
 197         if (rxfifo_cnt > 0)
 198                 return 1;
 199
 200         rx = max3100_transfer(MAX3100_RD);
 201         if ((rx & MAX3100_R) == 0)
 202                 return 0;
 203
 204         do {
 205                 rxfifo_cnt++;
 206                 rxfifo_buf[rxfifo_in++] = rx & 0xff;
 207                 rxfifo_in &= RXFIFO_SZ - 1;
 208
 209                 if (rxfifo_cnt >= RXFIFO_SZ)
 210                         break;
 211         } while (((rx = max3100_transfer(MAX3100_RD)) & MAX3100_R) != 0);
 212
 213         return 1;
 214 }
 215
 216 int serial_init(void)
 217 {
 218         unsigned int wconf, rconf;
 219         int i;
 220         DECLARE_GLOBAL_DATA_PTR;
 221
 222         wconf = 0;
 223
 224         /* Set baud rate */
 225         switch (gd->baudrate) {
 226                 case 1200:
 227                         wconf = MAX3100_B_1200;
 228                         break;
 229                 case 2400:
 230                         wconf = MAX3100_B_2400;
 231                         break;
 232                 case 4800:
 233                         wconf = MAX3100_B_4800;
 234                         break;
 235                 case 9600:
 236                         wconf = MAX3100_B_9600;
 237                         break;
 238                 case 19200:
 239                         wconf = MAX3100_B_19200;
 240                         break;
 241                 case 38400:
 242                         wconf = MAX3100_B_38400;
 243                         break;
 244                 case 57600:
 245                         wconf = MAX3100_B_57600;
 246                         break;
 247                 default:
 248                 case 115200:
 249                         wconf = MAX3100_B_115200;
 250                         break;
 251                 case 230400:
 252                         wconf = MAX3100_B_230400;
 253                         break;
 254         }
 255
 256         /* try for 10ms, with a 100us gap */
 257         for (i = 0; i < 10000; i += 100) {
 258
 259                 max3100_transfer(MAX3100_WC | wconf);
 260                 rconf = max3100_transfer(MAX3100_RC) & 0x3fff;
 261
 262                 if (rconf == wconf)
 263                         break;
 264                 udelay(100);
 265         }
 266
 267         rxfifo_in = rxfifo_out = rxfifo_cnt = 0;
 268
 269         return (0);
 270 }
 271
 272 void serial_putc(const char c)
 273 {
 274         if (c == '\n')
 275                 max3100_putc('\r');
 276
 277         max3100_putc(c);
 278 }
 279
 280 void serial_puts(const char *s)
 281 {
 282         while (*s)
 283                 serial_putc (*s++);
 284 }
 285
 286 int serial_getc(void)
 287 {
 288         return max3100_getc();
 289 }
 290
 291 int serial_tstc(void)
 292 {
 293         return max3100_tstc();
 294 }
 295
 296 /* XXX WTF? */
 297 void serial_setbrg(void)
 298 {
 299 }
 300
 301 #endif