drivers/serial/serial_max3100.c

   1 /*
   2  * (C) Copyright 2003
   3  *
   4  * Pantelis Antoniou <panto@intracom.gr>
   5  * Intracom S.A.
   6  *
   7  * SPDX-License-Identifier:     GPL-2.0+
   8  */
   9
  10 #include <common.h>
  11 #include <watchdog.h>
  12 #include <serial.h>
  13 #include <linux/compiler.h>
  14
  15 DECLARE_GLOBAL_DATA_PTR;
  16
  17 /**************************************************************/
  18
  19 /* convienient macros */
  20 #define MAX3100_SPI_RXD() (MAX3100_SPI_RXD_PORT & MAX3100_SPI_RXD_BIT)
  21
  22 #define MAX3100_SPI_TXD(x) \
  23         do { \
  24                 if (x) \
  25                         MAX3100_SPI_TXD_PORT |=  MAX3100_SPI_TXD_BIT; \
  26                 else \
  27                         MAX3100_SPI_TXD_PORT &= ~MAX3100_SPI_TXD_BIT; \
  28         } while(0)
  29
  30 #define MAX3100_SPI_CLK(x) \
  31         do { \
  32                 if (x) \
  33                         MAX3100_SPI_CLK_PORT |=  MAX3100_SPI_CLK_BIT; \
  34                 else \
  35                         MAX3100_SPI_CLK_PORT &= ~MAX3100_SPI_CLK_BIT; \
  36         } while(0)
  37
  38 #define MAX3100_SPI_CLK_TOGGLE() (MAX3100_SPI_CLK_PORT ^= MAX3100_SPI_CLK_BIT)
  39
  40 #define MAX3100_CS(x) \
  41         do { \
  42                 if (x) \
  43                         MAX3100_CS_PORT |=  MAX3100_CS_BIT; \
  44                 else \
  45                         MAX3100_CS_PORT &= ~MAX3100_CS_BIT; \
  46         } while(0)
  47
  48 /**************************************************************/
  49
  50 /* MAX3100 definitions */
  51
  52 #define MAX3100_WC      (3 << 14)               /* write configuration */
  53 #define MAX3100_RC      (1 << 14)               /* read  configuration */
  54 #define MAX3100_WD      (2 << 14)               /* write data          */
  55 #define MAX3100_RD      (0 << 14)               /* read  data          */
  56
  57 /* configuration register bits */
  58 #define MAX3100_FEN     (1 << 13)               /* FIFO enable           */
  59 #define MAX3100_SHDN    (1 << 12)               /* shutdown bit          */
  60 #define MAX3100_TM      (1 << 11)               /* T bit irq mask        */
  61 #define MAX3100_RM      (1 << 10)               /* R bit irq mask        */
  62 #define MAX3100_PM      (1 <<  9)               /* P bit irq mask        */
  63 #define MAX3100_RAM     (1 <<  8)               /* mask for RA/FE bit    */
  64 #define MAX3100_IR      (1 <<  7)               /* IRDA timing mode      */
  65 #define MAX3100_ST      (1 <<  6)               /* transmit stop bit     */
  66 #define MAX3100_PE      (1 <<  5)               /* parity enable bit     */
  67 #define MAX3100_L       (1 <<  4)               /* Length bit            */
  68 #define MAX3100_B_MASK  (0x000F)                /* baud rate bits mask   */
  69 #define MAX3100_B(x)    ((x) & 0x000F)  /* baud rate select bits */
  70
  71 /* data register bits (write) */
  72 #define MAX3100_TE      (1 << 10)               /* transmit enable bit (active low)        */
  73 #define MAX3100_RTS     (1 <<  9)               /* request-to-send bit (inverted ~RTS pin) */
  74
  75 /* data register bits (read) */
  76 #define MAX3100_RA      (1 << 10)               /* receiver activity when in shutdown mode */
  77 #define MAX3100_FE      (1 << 10)               /* framing error when in normal mode       */
  78 #define MAX3100_CTS     (1 <<  9)               /* clear-to-send bit (inverted ~CTS pin)   */
  79
  80 /* data register bits (both directions) */
  81 #define MAX3100_R       (1 << 15)               /* receive bit    */
  82 #define MAX3100_T       (1 << 14)               /* transmit bit   */
  83 #define MAX3100_P       (1 <<  8)               /* parity bit     */
  84 #define MAX3100_D_MASK  0x00FF                  /* data bits mask */
  85 #define MAX3100_D(x)    ((x) & 0x00FF)          /* data bits      */
  86
  87 /* these definitions are valid only for fOSC = 3.6864MHz */
  88 #define MAX3100_B_230400        MAX3100_B(0)
  89 #define MAX3100_B_115200        MAX3100_B(1)
  90 #define MAX3100_B_57600         MAX3100_B(2)
  91 #define MAX3100_B_38400         MAX3100_B(9)
  92 #define MAX3100_B_19200         MAX3100_B(10)
  93 #define MAX3100_B_9600          MAX3100_B(11)
  94 #define MAX3100_B_4800          MAX3100_B(12)
  95 #define MAX3100_B_2400          MAX3100_B(13)
  96 #define MAX3100_B_1200          MAX3100_B(14)
  97 #define MAX3100_B_600           MAX3100_B(15)
  98
  99 /**************************************************************/
 100
 101 static inline unsigned int max3100_transfer(unsigned int val)
 102 {
 103         unsigned int rx;
 104         int b;
 105
 106         MAX3100_SPI_CLK(0);
 107         MAX3100_CS(0);
 108
 109         rx = 0; b = 16;
 110         while (--b >= 0) {
 111                 MAX3100_SPI_TXD(val & 0x8000);
 112                 val <<= 1;
 113                 MAX3100_SPI_CLK_TOGGLE();
 114                 udelay(1);
 115                 rx <<= 1;
 116                 if (MAX3100_SPI_RXD())
 117                         rx |= 1;
 118                 MAX3100_SPI_CLK_TOGGLE();
 119                 udelay(1);
 120         }
 121
 122         MAX3100_SPI_CLK(1);
 123         MAX3100_CS(1);
 124
 125         return rx;
 126 }
 127
 128 /**************************************************************/
 129
 130 /* must be power of 2 */
 131 #define RXFIFO_SZ       16
 132
 133 static int rxfifo_cnt;
 134 static int rxfifo_in;
 135 static int rxfifo_out;
 136 static unsigned char rxfifo_buf[16];
 137
 138 static void max3100_serial_putc_raw(int c)
 139 {
 140         unsigned int rx;
 141
 142         while (((rx = max3100_transfer(MAX3100_RC)) & MAX3100_T) == 0)
 143                 WATCHDOG_RESET();
 144
 145         rx = max3100_transfer(MAX3100_WD | (c & 0xff));
 146         if ((rx & MAX3100_RD) != 0 && rxfifo_cnt < RXFIFO_SZ) {
 147                 rxfifo_cnt++;
 148                 rxfifo_buf[rxfifo_in++] = rx & 0xff;
 149                 rxfifo_in &= RXFIFO_SZ - 1;
 150         }
 151 }
 152
 153 static int max3100_serial_getc(void)
 154 {
 155         int c;
 156         unsigned int rx;
 157
 158         while (rxfifo_cnt == 0) {
 159                 rx = max3100_transfer(MAX3100_RD);
 160                 if ((rx & MAX3100_R) != 0) {
 161                         do {
 162                                 rxfifo_cnt++;
 163                                 rxfifo_buf[rxfifo_in++] = rx & 0xff;
 164                                 rxfifo_in &= RXFIFO_SZ - 1;
 165
 166                                 if (rxfifo_cnt >= RXFIFO_SZ)
 167                                         break;
 168                         } while (((rx = max3100_transfer(MAX3100_RD)) & MAX3100_R) != 0);
 169                 }
 170                 WATCHDOG_RESET();
 171         }
 172
 173         rxfifo_cnt--;
 174         c = rxfifo_buf[rxfifo_out++];
 175         rxfifo_out &= RXFIFO_SZ - 1;
 176         return c;
 177 }
 178
 179 static int max3100_serial_tstc(void)
 180 {
 181         unsigned int rx;
 182
 183         if (rxfifo_cnt > 0)
 184                 return 1;
 185
 186         rx = max3100_transfer(MAX3100_RD);
 187         if ((rx & MAX3100_R) == 0)
 188                 return 0;
 189
 190         do {
 191                 rxfifo_cnt++;
 192                 rxfifo_buf[rxfifo_in++] = rx & 0xff;
 193                 rxfifo_in &= RXFIFO_SZ - 1;
 194
 195                 if (rxfifo_cnt >= RXFIFO_SZ)
 196                         break;
 197         } while (((rx = max3100_transfer(MAX3100_RD)) & MAX3100_R) != 0);
 198
 199         return 1;
 200 }
 201
 202 static int max3100_serial_init(void)
 203 {
 204         unsigned int wconf, rconf;
 205         int i;
 206
 207         wconf = 0;
 208
 209         /* Set baud rate */
 210         switch (gd->baudrate) {
 211                 case 1200:
 212                         wconf = MAX3100_B_1200;
 213                         break;
 214                 case 2400:
 215                         wconf = MAX3100_B_2400;
 216                         break;
 217                 case 4800:
 218                         wconf = MAX3100_B_4800;
 219                         break;
 220                 case 9600:
 221                         wconf = MAX3100_B_9600;
 222                         break;
 223                 case 19200:
 224                         wconf = MAX3100_B_19200;
 225                         break;
 226                 case 38400:
 227                         wconf = MAX3100_B_38400;
 228                         break;
 229                 case 57600:
 230                         wconf = MAX3100_B_57600;
 231                         break;
 232                 default:
 233                 case 115200:
 234                         wconf = MAX3100_B_115200;
 235                         break;
 236                 case 230400:
 237                         wconf = MAX3100_B_230400;
 238                         break;
 239         }
 240
 241         /* try for 10ms, with a 100us gap */
 242         for (i = 0; i < 10000; i += 100) {
 243
 244                 max3100_transfer(MAX3100_WC | wconf);
 245                 rconf = max3100_transfer(MAX3100_RC) & 0x3fff;
 246
 247                 if (rconf == wconf)
 248                         break;
 249                 udelay(100);
 250         }
 251
 252         rxfifo_in = rxfifo_out = rxfifo_cnt = 0;
 253
 254         return (0);
 255 }
 256
 257 static void max3100_serial_putc(const char c)
 258 {
 259         if (c == '\n')
 260                 max3100_serial_putc_raw('\r');
 261
 262         max3100_serial_putc_raw(c);
 263 }
 264
 265 static void max3100_serial_puts(const char *s)
 266 {
 267         while (*s)
 268                 max3100_serial_putc_raw(*s++);
 269 }
 270
 271 static void max3100_serial_setbrg(void)
 272 {
 273 }
 274
 275 static struct serial_device max3100_serial_drv = {
 276         .name   = "max3100_serial",
 277         .start  = max3100_serial_init,
 278         .stop   = NULL,
 279         .setbrg = max3100_serial_setbrg,
 280         .putc   = max3100_serial_putc,
 281         .puts   = max3100_serial_puts,
 282         .getc   = max3100_serial_getc,
 283         .tstc   = max3100_serial_tstc,
 284 };
 285
 286 void max3100_serial_initialize(void)
 287 {
 288         serial_register(&max3100_serial_drv);
 289 }
 290
 291 __weak struct serial_device *default_serial_console(void)
 292 {
 293         return &max3100_serial_drv;
 294 }