drivers/acorn/char/i2c.c

   1 /*
   2  *  linux/drivers/acorn/char/i2c.c
   3  *
   4  *  Copyright (C) 2000 Russell King
   5  *
   6  * This program is free software; you can redistribute it and/or modify
   7  * it under the terms of the GNU General Public License version 2 as
   8  * published by the Free Software Foundation.
   9  *
  10  *  ARM IOC/IOMD i2c driver.
  11  *
  12  *  On Acorn machines, the following i2c devices are on the bus:
  13  *      - PCF8583 real time clock & static RAM
  14  */
  15 #include <linux/capability.h>
  16 #include <linux/init.h>
  17 #include <linux/sched.h>
  18 #include <linux/time.h>
  19 #include <linux/miscdevice.h>
  20 #include <linux/rtc.h>
  21 #include <linux/i2c.h>
  22 #include <linux/i2c-algo-bit.h>
  23 #include <linux/fs.h>
  24
  25 #include <asm/hardware.h>
  26 #include <asm/io.h>
  27 #include <asm/hardware/ioc.h>
  28 #include <asm/system.h>
  29 #include <asm/uaccess.h>
  30
  31 #include "pcf8583.h"
  32
  33 extern int (*set_rtc)(void);
  34
  35 static struct i2c_client *rtc_client;
  36 static const unsigned char days_in_mon[] =
  37         { 0, 31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31 };
  38
  39 #define CMOS_CHECKSUM   (63)
  40
  41 /*
  42  * Acorn machines store the year in the static RAM at
  43  * location 128.
  44  */
  45 #define CMOS_YEAR       (64 + 128)
  46
  47 static inline int rtc_command(int cmd, void *data)
  48 {
  49         int ret = -EIO;
  50
  51         if (rtc_client)
  52                 ret = rtc_client->driver->command(rtc_client, cmd, data);
  53
  54         return ret;
  55 }
  56
  57 /*
  58  * Update the century + year bytes in the CMOS RAM, ensuring
  59  * that the check byte is correctly adjusted for the change.
  60  */
  61 static int rtc_update_year(unsigned int new_year)
  62 {
  63         unsigned char yr[2], chk;
  64         struct mem cmos_year  = { CMOS_YEAR, sizeof(yr), yr };
  65         struct mem cmos_check = { CMOS_CHECKSUM, 1, &chk };
  66         int ret;
  67
  68         ret = rtc_command(MEM_READ, &cmos_check);
  69         if (ret)
  70                 goto out;
  71         ret = rtc_command(MEM_READ, &cmos_year);
  72         if (ret)
  73                 goto out;
  74
  75         chk -= yr[1] + yr[0];
  76
  77         yr[1] = new_year / 100;
  78         yr[0] = new_year % 100;
  79
  80         chk += yr[1] + yr[0];
  81
  82         ret = rtc_command(MEM_WRITE, &cmos_year);
  83         if (ret == 0)
  84                 ret = rtc_command(MEM_WRITE, &cmos_check);
  85  out:
  86         return ret;
  87 }
  88
  89 /*
  90  * Read the current RTC time and date, and update xtime.
  91  */
  92 static void get_rtc_time(struct rtc_tm *rtctm, unsigned int *year)
  93 {
  94         unsigned char ctrl, yr[2];
  95         struct mem rtcmem = { CMOS_YEAR, sizeof(yr), yr };
  96         int real_year, year_offset;
  97
  98         /*
  99          * Ensure that the RTC is running.
 100          */
 101         rtc_command(RTC_GETCTRL, &ctrl);
 102         if (ctrl & 0xc0) {
 103                 unsigned char new_ctrl = ctrl & ~0xc0;
 104
 105                 printk(KERN_WARNING "RTC: resetting control %02x -> %02x\n",
 106                        ctrl, new_ctrl);
 107
 108                 rtc_command(RTC_SETCTRL, &new_ctrl);
 109         }
 110
 111         if (rtc_command(RTC_GETDATETIME, rtctm) ||
 112             rtc_command(MEM_READ, &rtcmem))
 113                 return;
 114
 115         real_year = yr[0];
 116
 117         /*
 118          * The RTC year holds the LSB two bits of the current
 119          * year, which should reflect the LSB two bits of the
 120          * CMOS copy of the year.  Any difference indicates
 121          * that we have to correct the CMOS version.
 122          */
 123         year_offset = rtctm->year_off - (real_year & 3);
 124         if (year_offset < 0)
 125                 /*
 126                  * RTC year wrapped.  Adjust it appropriately.
 127                  */
 128                 year_offset += 4;
 129
 130         *year = real_year + year_offset + yr[1] * 100;
 131 }
 132
 133 static int set_rtc_time(struct rtc_tm *rtctm, unsigned int year)
 134 {
 135         unsigned char leap;
 136         int ret;
 137
 138         leap = (!(year % 4) && (year % 100)) || !(year % 400);
 139
 140         if (rtctm->mon > 12 || rtctm->mon == 0 || rtctm->mday == 0)
 141                 return -EINVAL;
 142
 143         if (rtctm->mday > (days_in_mon[rtctm->mon] + (rtctm->mon == 2 && leap)))
 144                 return -EINVAL;
 145
 146         if (rtctm->hours >= 24 || rtctm->mins >= 60 || rtctm->secs >= 60)
 147                 return -EINVAL;
 148
 149         /*
 150          * The RTC's own 2-bit year must reflect the least
 151          * significant two bits of the CMOS year.
 152          */
 153         rtctm->year_off = (year % 100) & 3;
 154
 155         ret = rtc_command(RTC_SETDATETIME, rtctm);
 156         if (ret == 0)
 157                 ret = rtc_update_year(year);
 158
 159         return ret;
 160 }
 161
 162 /*
 163  * Set the RTC time only.  Note that
 164  * we do not touch the date.
 165  */
 166 static int k_set_rtc_time(void)
 167 {
 168         struct rtc_tm new_rtctm, old_rtctm;
 169         unsigned long nowtime = xtime.tv_sec;
 170
 171         if (rtc_command(RTC_GETDATETIME, &old_rtctm))
 172                 return 0;
 173
 174         new_rtctm.cs    = xtime.tv_nsec / 10000000;
 175         new_rtctm.secs  = nowtime % 60; nowtime /= 60;
 176         new_rtctm.mins  = nowtime % 60; nowtime /= 60;
 177         new_rtctm.hours = nowtime % 24;
 178
 179         /*
 180          * avoid writing when we're going to change the day
 181          * of the month.  We will retry in the next minute.
 182          * This basically means that if the RTC must not drift
 183          * by more than 1 minute in 11 minutes.
 184          *
 185          * [ rtc: 1/1/2000 23:58:00, real 2/1/2000 00:01:00,
 186          *   rtc gets set to 1/1/2000 00:01:00 ]
 187          */
 188         if ((old_rtctm.hours == 23 && old_rtctm.mins == 59) ||
 189             (new_rtctm.hours == 23 && new_rtctm.mins == 59))
 190                 return 1;
 191
 192         return rtc_command(RTC_SETTIME, &new_rtctm);
 193 }
 194
 195 static int rtc_ioctl(struct inode *inode, struct file *file,
 196                      unsigned int cmd, unsigned long arg)
 197 {
 198         unsigned int year;
 199         struct rtc_time rtctm;
 200         struct rtc_tm rtc_raw;
 201
 202         switch (cmd) {
 203         case RTC_ALM_READ:
 204         case RTC_ALM_SET:
 205                 break;
 206
 207         case RTC_RD_TIME:
 208                 memset(&rtctm, 0, sizeof(struct rtc_time));
 209                 get_rtc_time(&rtc_raw, &year);
 210                 rtctm.tm_sec  = rtc_raw.secs;
 211                 rtctm.tm_min  = rtc_raw.mins;
 212                 rtctm.tm_hour = rtc_raw.hours;
 213                 rtctm.tm_mday = rtc_raw.mday;
 214                 rtctm.tm_mon  = rtc_raw.mon - 1; /* month starts at 0 */
 215                 rtctm.tm_year = year - 1900; /* starts at 1900 */
 216                 return copy_to_user((void *)arg, &rtctm, sizeof(rtctm))
 217                                  ? -EFAULT : 0;
 218
 219         case RTC_SET_TIME:
 220                 if (!capable(CAP_SYS_TIME))
 221                         return -EACCES;
 222
 223                 if (copy_from_user(&rtctm, (void *)arg, sizeof(rtctm)))
 224                         return -EFAULT;
 225                 rtc_raw.secs     = rtctm.tm_sec;
 226                 rtc_raw.mins     = rtctm.tm_min;
 227                 rtc_raw.hours    = rtctm.tm_hour;
 228                 rtc_raw.mday     = rtctm.tm_mday;
 229                 rtc_raw.mon      = rtctm.tm_mon + 1;
 230                 year             = rtctm.tm_year + 1900;
 231                 return set_rtc_time(&rtc_raw, year);
 232                 break;
 233
 234         case RTC_EPOCH_READ:
 235                 return put_user(1900, (unsigned long *)arg);
 236
 237         }
 238         return -EINVAL;
 239 }
 240
 241 static struct file_operations rtc_fops = {
 242         .ioctl  = rtc_ioctl,
 243 };
 244
 245 static struct miscdevice rtc_dev = {
 246         .minor  = RTC_MINOR,
 247         .name   = "rtc",
 248         .fops   = &rtc_fops,
 249 };
 250
 251 /* IOC / IOMD i2c driver */
 252
 253 #define FORCE_ONES      0xdc
 254 #define SCL             0x02
 255 #define SDA             0x01
 256
 257 /*
 258  * We must preserve all non-i2c output bits in IOC_CONTROL.
 259  * Note also that we need to preserve the value of SCL and
 260  * SDA outputs as well (which may be different from the
 261  * values read back from IOC_CONTROL).
 262  */
 263 static u_int force_ones;
 264
 265 static void ioc_setscl(void *data, int state)
 266 {
 267         u_int ioc_control = ioc_readb(IOC_CONTROL) & ~(SCL | SDA);
 268         u_int ones = force_ones;
 269
 270         if (state)
 271                 ones |= SCL;
 272         else
 273                 ones &= ~SCL;
 274
 275         force_ones = ones;
 276
 277         ioc_writeb(ioc_control | ones, IOC_CONTROL);
 278 }
 279
 280 static void ioc_setsda(void *data, int state)
 281 {
 282         u_int ioc_control = ioc_readb(IOC_CONTROL) & ~(SCL | SDA);
 283         u_int ones = force_ones;
 284
 285         if (state)
 286                 ones |= SDA;
 287         else
 288                 ones &= ~SDA;
 289
 290         force_ones = ones;
 291
 292         ioc_writeb(ioc_control | ones, IOC_CONTROL);
 293 }
 294
 295 static int ioc_getscl(void *data)
 296 {
 297         return (ioc_readb(IOC_CONTROL) & SCL) != 0;
 298 }
 299
 300 static int ioc_getsda(void *data)
 301 {
 302         return (ioc_readb(IOC_CONTROL) & SDA) != 0;
 303 }
 304
 305 static struct i2c_algo_bit_data ioc_data = {
 306         .setsda         = ioc_setsda,
 307         .setscl         = ioc_setscl,
 308         .getsda         = ioc_getsda,
 309         .getscl         = ioc_getscl,
 310         .udelay         = 80,
 311         .timeout        = 100
 312 };
 313
 314 static int ioc_client_reg(struct i2c_client *client)
 315 {
 316         if (client->driver->id == I2C_DRIVERID_PCF8583 &&
 317             client->addr == 0x50) {
 318                 struct rtc_tm rtctm;
 319                 unsigned int year;
 320                 struct timespec tv;
 321
 322                 rtc_client = client;
 323                 get_rtc_time(&rtctm, &year);
 324
 325                 tv.tv_nsec = rtctm.cs * 10000000;
 326                 tv.tv_sec  = mktime(year, rtctm.mon, rtctm.mday,
 327                                     rtctm.hours, rtctm.mins, rtctm.secs);
 328                 do_settimeofday(&tv);
 329                 set_rtc = k_set_rtc_time;
 330         }
 331
 332         return 0;
 333 }
 334
 335 static int ioc_client_unreg(struct i2c_client *client)
 336 {
 337         if (client == rtc_client) {
 338                 set_rtc = NULL;
 339                 rtc_client = NULL;
 340         }
 341
 342         return 0;
 343 }
 344
 345 static struct i2c_adapter ioc_ops = {
 346         .id                     = I2C_HW_B_IOC,
 347         .algo_data              = &ioc_data,
 348         .client_register        = ioc_client_reg,
 349         .client_unregister      = ioc_client_unreg,
 350 };
 351
 352 static int __init i2c_ioc_init(void)
 353 {
 354         int ret;
 355
 356         force_ones = FORCE_ONES | SCL | SDA;
 357
 358         ret = i2c_bit_add_bus(&ioc_ops);
 359
 360         if (ret >= 0){
 361                 ret = misc_register(&rtc_dev);
 362                 if(ret < 0)
 363                         i2c_del_adapter(&ioc_ops);
 364         }
 365
 366         return ret;
 367 }
 368
 369 __initcall(i2c_ioc_init);