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   1 /*
   2  * drivers/i2c/chips/m41t00.c
   3  *
   4  * I2C client/driver for the ST M41T00 Real-Time Clock chip.
   5  *
   6  * Author: Mark A. Greer <mgreer@mvista.com>
   7  *
   8  * 2005 (c) MontaVista Software, Inc. This file is licensed under
   9  * the terms of the GNU General Public License version 2. This program
  10  * is licensed "as is" without any warranty of any kind, whether express
  11  * or implied.
  12  */
  13 /*
  14  * This i2c client/driver wedges between the drivers/char/genrtc.c RTC
  15  * interface and the SMBus interface of the i2c subsystem.
  16  * It would be more efficient to use i2c msgs/i2c_transfer directly but, as
  17  * recommened in .../Documentation/i2c/writing-clients section
  18  * "Sending and receiving", using SMBus level communication is preferred.
  19  */
  20
  21 #include <linux/kernel.h>
  22 #include <linux/module.h>
  23 #include <linux/interrupt.h>
  24 #include <linux/i2c.h>
  25 #include <linux/rtc.h>
  26 #include <linux/bcd.h>
  27
  28 #include <asm/time.h>
  29 #include <asm/rtc.h>
  30
  31 #define M41T00_DRV_NAME         "m41t00"
  32
  33 static DECLARE_MUTEX(m41t00_mutex);
  34
  35 static struct i2c_driver m41t00_driver;
  36 static struct i2c_client *save_client;
  37
  38 static unsigned short ignore[] = { I2C_CLIENT_END };
  39 static unsigned short normal_addr[] = { 0x68, I2C_CLIENT_END };
  40
  41 static struct i2c_client_address_data addr_data = {
  42         .normal_i2c             = normal_addr,
  43         .probe                  = ignore,
  44         .ignore                 = ignore,
  45 };
  46
  47 ulong
  48 m41t00_get_rtc_time(void)
  49 {
  50         s32     sec, min, hour, day, mon, year;
  51         s32     sec1, min1, hour1, day1, mon1, year1;
  52         ulong   limit = 10;
  53
  54         sec = min = hour = day = mon = year = 0;
  55         sec1 = min1 = hour1 = day1 = mon1 = year1 = 0;
  56
  57         down(&m41t00_mutex);
  58         do {
  59                 if (((sec = i2c_smbus_read_byte_data(save_client, 0)) >= 0)
  60                         && ((min = i2c_smbus_read_byte_data(save_client, 1))
  61                                 >= 0)
  62                         && ((hour = i2c_smbus_read_byte_data(save_client, 2))
  63                                 >= 0)
  64                         && ((day = i2c_smbus_read_byte_data(save_client, 4))
  65                                 >= 0)
  66                         && ((mon = i2c_smbus_read_byte_data(save_client, 5))
  67                                 >= 0)
  68                         && ((year = i2c_smbus_read_byte_data(save_client, 6))
  69                                 >= 0)
  70                         && ((sec == sec1) && (min == min1) && (hour == hour1)
  71                                 && (day == day1) && (mon == mon1)
  72                                 && (year == year1)))
  73
  74                                 break;
  75
  76                 sec1 = sec;
  77                 min1 = min;
  78                 hour1 = hour;
  79                 day1 = day;
  80                 mon1 = mon;
  81                 year1 = year;
  82         } while (--limit > 0);
  83         up(&m41t00_mutex);
  84
  85         if (limit == 0) {
  86                 dev_warn(&save_client->dev,
  87                         "m41t00: can't read rtc chip\n");
  88                 sec = min = hour = day = mon = year = 0;
  89         }
  90
  91         sec &= 0x7f;
  92         min &= 0x7f;
  93         hour &= 0x3f;
  94         day &= 0x3f;
  95         mon &= 0x1f;
  96         year &= 0xff;
  97
  98         BCD_TO_BIN(sec);
  99         BCD_TO_BIN(min);
 100         BCD_TO_BIN(hour);
 101         BCD_TO_BIN(day);
 102         BCD_TO_BIN(mon);
 103         BCD_TO_BIN(year);
 104
 105         year += 1900;
 106         if (year < 1970)
 107                 year += 100;
 108
 109         return mktime(year, mon, day, hour, min, sec);
 110 }
 111
 112 static void
 113 m41t00_set_tlet(ulong arg)
 114 {
 115         struct rtc_time tm;
 116         ulong   nowtime = *(ulong *)arg;
 117
 118         to_tm(nowtime, &tm);
 119         tm.tm_year = (tm.tm_year - 1900) % 100;
 120
 121         BIN_TO_BCD(tm.tm_sec);
 122         BIN_TO_BCD(tm.tm_min);
 123         BIN_TO_BCD(tm.tm_hour);
 124         BIN_TO_BCD(tm.tm_mon);
 125         BIN_TO_BCD(tm.tm_mday);
 126         BIN_TO_BCD(tm.tm_year);
 127
 128         down(&m41t00_mutex);
 129         if ((i2c_smbus_write_byte_data(save_client, 0, tm.tm_sec & 0x7f) < 0)
 130                 || (i2c_smbus_write_byte_data(save_client, 1, tm.tm_min & 0x7f)
 131                         < 0)
 132                 || (i2c_smbus_write_byte_data(save_client, 2, tm.tm_hour & 0x7f)
 133                         < 0)
 134                 || (i2c_smbus_write_byte_data(save_client, 4, tm.tm_mday & 0x7f)
 135                         < 0)
 136                 || (i2c_smbus_write_byte_data(save_client, 5, tm.tm_mon & 0x7f)
 137                         < 0)
 138                 || (i2c_smbus_write_byte_data(save_client, 6, tm.tm_year & 0x7f)
 139                         < 0))
 140
 141                 dev_warn(&save_client->dev,"m41t00: can't write to rtc chip\n");
 142
 143         up(&m41t00_mutex);
 144         return;
 145 }
 146
 147 static ulong    new_time;
 148
 149 DECLARE_TASKLET_DISABLED(m41t00_tasklet, m41t00_set_tlet, (ulong)&new_time);
 150
 151 int
 152 m41t00_set_rtc_time(ulong nowtime)
 153 {
 154         new_time = nowtime;
 155
 156         if (in_interrupt())
 157                 tasklet_schedule(&m41t00_tasklet);
 158         else
 159                 m41t00_set_tlet((ulong)&new_time);
 160
 161         return 0;
 162 }
 163
 164 /*
 165  *****************************************************************************
 166  *
 167  *      Driver Interface
 168  *
 169  *****************************************************************************
 170  */
 171 static int
 172 m41t00_probe(struct i2c_adapter *adap, int addr, int kind)
 173 {
 174         struct i2c_client *client;
 175         int rc;
 176
 177         client = kzalloc(sizeof(struct i2c_client), GFP_KERNEL);
 178         if (!client)
 179                 return -ENOMEM;
 180
 181         strncpy(client->name, M41T00_DRV_NAME, I2C_NAME_SIZE);
 182         client->addr = addr;
 183         client->adapter = adap;
 184         client->driver = &m41t00_driver;
 185
 186         if ((rc = i2c_attach_client(client)) != 0) {
 187                 kfree(client);
 188                 return rc;
 189         }
 190
 191         save_client = client;
 192         return 0;
 193 }
 194
 195 static int
 196 m41t00_attach(struct i2c_adapter *adap)
 197 {
 198         return i2c_probe(adap, &addr_data, m41t00_probe);
 199 }
 200
 201 static int
 202 m41t00_detach(struct i2c_client *client)
 203 {
 204         int     rc;
 205
 206         if ((rc = i2c_detach_client(client)) == 0) {
 207                 kfree(client);
 208                 tasklet_kill(&m41t00_tasklet);
 209         }
 210         return rc;
 211 }
 212
 213 static struct i2c_driver m41t00_driver = {
 214         .owner          = THIS_MODULE,
 215         .name           = M41T00_DRV_NAME,
 216         .id             = I2C_DRIVERID_STM41T00,
 217         .flags          = I2C_DF_NOTIFY,
 218         .attach_adapter = m41t00_attach,
 219         .detach_client  = m41t00_detach,
 220 };
 221
 222 static int __init
 223 m41t00_init(void)
 224 {
 225         return i2c_add_driver(&m41t00_driver);
 226 }
 227
 228 static void __exit
 229 m41t00_exit(void)
 230 {
 231         i2c_del_driver(&m41t00_driver);
 232         return;
 233 }
 234
 235 module_init(m41t00_init);
 236 module_exit(m41t00_exit);
 237
 238 MODULE_AUTHOR("Mark A. Greer <mgreer@mvista.com>");
 239 MODULE_DESCRIPTION("ST Microelectronics M41T00 RTC I2C Client Driver");
 240 MODULE_LICENSE("GPL");