drivers/i2c/chips/m41t00.c

   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 #include <linux/mutex.h>
  28 #include <linux/workqueue.h>
  29
  30 #include <asm/time.h>
  31 #include <asm/rtc.h>
  32
  33 #define M41T00_DRV_NAME         "m41t00"
  34
  35 static DEFINE_MUTEX(m41t00_mutex);
  36
  37 static struct i2c_driver m41t00_driver;
  38 static struct i2c_client *save_client;
  39
  40 static unsigned short ignore[] = { I2C_CLIENT_END };
  41 static unsigned short normal_addr[] = { 0x68, I2C_CLIENT_END };
  42
  43 static struct i2c_client_address_data addr_data = {
  44         .normal_i2c             = normal_addr,
  45         .probe                  = ignore,
  46         .ignore                 = ignore,
  47 };
  48
  49 ulong
  50 m41t00_get_rtc_time(void)
  51 {
  52         s32     sec, min, hour, day, mon, year;
  53         s32     sec1, min1, hour1, day1, mon1, year1;
  54         ulong   limit = 10;
  55
  56         sec = min = hour = day = mon = year = 0;
  57         sec1 = min1 = hour1 = day1 = mon1 = year1 = 0;
  58
  59         mutex_lock(&m41t00_mutex);
  60         do {
  61                 if (((sec = i2c_smbus_read_byte_data(save_client, 0)) >= 0)
  62                         && ((min = i2c_smbus_read_byte_data(save_client, 1))
  63                                 >= 0)
  64                         && ((hour = i2c_smbus_read_byte_data(save_client, 2))
  65                                 >= 0)
  66                         && ((day = i2c_smbus_read_byte_data(save_client, 4))
  67                                 >= 0)
  68                         && ((mon = i2c_smbus_read_byte_data(save_client, 5))
  69                                 >= 0)
  70                         && ((year = i2c_smbus_read_byte_data(save_client, 6))
  71                                 >= 0)
  72                         && ((sec == sec1) && (min == min1) && (hour == hour1)
  73                                 && (day == day1) && (mon == mon1)
  74                                 && (year == year1)))
  75
  76                                 break;
  77
  78                 sec1 = sec;
  79                 min1 = min;
  80                 hour1 = hour;
  81                 day1 = day;
  82                 mon1 = mon;
  83                 year1 = year;
  84         } while (--limit > 0);
  85         mutex_unlock(&m41t00_mutex);
  86
  87         if (limit == 0) {
  88                 dev_warn(&save_client->dev,
  89                         "m41t00: can't read rtc chip\n");
  90                 sec = min = hour = day = mon = year = 0;
  91         }
  92
  93         sec &= 0x7f;
  94         min &= 0x7f;
  95         hour &= 0x3f;
  96         day &= 0x3f;
  97         mon &= 0x1f;
  98         year &= 0xff;
  99
 100         BCD_TO_BIN(sec);
 101         BCD_TO_BIN(min);
 102         BCD_TO_BIN(hour);
 103         BCD_TO_BIN(day);
 104         BCD_TO_BIN(mon);
 105         BCD_TO_BIN(year);
 106
 107         year += 1900;
 108         if (year < 1970)
 109                 year += 100;
 110
 111         return mktime(year, mon, day, hour, min, sec);
 112 }
 113
 114 static void
 115 m41t00_set(void *arg)
 116 {
 117         struct rtc_time tm;
 118         ulong   nowtime = *(ulong *)arg;
 119
 120         to_tm(nowtime, &tm);
 121         tm.tm_year = (tm.tm_year - 1900) % 100;
 122
 123         BIN_TO_BCD(tm.tm_sec);
 124         BIN_TO_BCD(tm.tm_min);
 125         BIN_TO_BCD(tm.tm_hour);
 126         BIN_TO_BCD(tm.tm_mon);
 127         BIN_TO_BCD(tm.tm_mday);
 128         BIN_TO_BCD(tm.tm_year);
 129
 130         mutex_lock(&m41t00_mutex);
 131         if ((i2c_smbus_write_byte_data(save_client, 0, tm.tm_sec & 0x7f) < 0)
 132                 || (i2c_smbus_write_byte_data(save_client, 1, tm.tm_min & 0x7f)
 133                         < 0)
 134                 || (i2c_smbus_write_byte_data(save_client, 2, tm.tm_hour & 0x3f)
 135                         < 0)
 136                 || (i2c_smbus_write_byte_data(save_client, 4, tm.tm_mday & 0x3f)
 137                         < 0)
 138                 || (i2c_smbus_write_byte_data(save_client, 5, tm.tm_mon & 0x1f)
 139                         < 0)
 140                 || (i2c_smbus_write_byte_data(save_client, 6, tm.tm_year & 0xff)
 141                         < 0))
 142
 143                 dev_warn(&save_client->dev,"m41t00: can't write to rtc chip\n");
 144
 145         mutex_unlock(&m41t00_mutex);
 146         return;
 147 }
 148
 149 static ulong new_time;
 150 static struct workqueue_struct *m41t00_wq;
 151 static DECLARE_WORK(m41t00_work, m41t00_set, &new_time);
 152
 153 int
 154 m41t00_set_rtc_time(ulong nowtime)
 155 {
 156         new_time = nowtime;
 157
 158         if (in_interrupt())
 159                 queue_work(m41t00_wq, &m41t00_work);
 160         else
 161                 m41t00_set(&new_time);
 162
 163         return 0;
 164 }
 165
 166 /*
 167  *****************************************************************************
 168  *
 169  *      Driver Interface
 170  *
 171  *****************************************************************************
 172  */
 173 static int
 174 m41t00_probe(struct i2c_adapter *adap, int addr, int kind)
 175 {
 176         struct i2c_client *client;
 177         int rc;
 178
 179         client = kzalloc(sizeof(struct i2c_client), GFP_KERNEL);
 180         if (!client)
 181                 return -ENOMEM;
 182
 183         strncpy(client->name, M41T00_DRV_NAME, I2C_NAME_SIZE);
 184         client->addr = addr;
 185         client->adapter = adap;
 186         client->driver = &m41t00_driver;
 187
 188         if ((rc = i2c_attach_client(client)) != 0) {
 189                 kfree(client);
 190                 return rc;
 191         }
 192
 193         m41t00_wq = create_singlethread_workqueue("m41t00");
 194         save_client = client;
 195         return 0;
 196 }
 197
 198 static int
 199 m41t00_attach(struct i2c_adapter *adap)
 200 {
 201         return i2c_probe(adap, &addr_data, m41t00_probe);
 202 }
 203
 204 static int
 205 m41t00_detach(struct i2c_client *client)
 206 {
 207         int     rc;
 208
 209         if ((rc = i2c_detach_client(client)) == 0) {
 210                 kfree(client);
 211                 destroy_workqueue(m41t00_wq);
 212         }
 213         return rc;
 214 }
 215
 216 static struct i2c_driver m41t00_driver = {
 217         .driver = {
 218                 .name   = M41T00_DRV_NAME,
 219         },
 220         .id             = I2C_DRIVERID_STM41T00,
 221         .attach_adapter = m41t00_attach,
 222         .detach_client  = m41t00_detach,
 223 };
 224
 225 static int __init
 226 m41t00_init(void)
 227 {
 228         return i2c_add_driver(&m41t00_driver);
 229 }
 230
 231 static void __exit
 232 m41t00_exit(void)
 233 {
 234         i2c_del_driver(&m41t00_driver);
 235         return;
 236 }
 237
 238 module_init(m41t00_init);
 239 module_exit(m41t00_exit);
 240
 241 MODULE_AUTHOR("Mark A. Greer <mgreer@mvista.com>");
 242 MODULE_DESCRIPTION("ST Microelectronics M41T00 RTC I2C Client Driver");
 243 MODULE_LICENSE("GPL");