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
  29 #include <asm/time.h>
  30 #include <asm/rtc.h>
  31
  32 #define M41T00_DRV_NAME         "m41t00"
  33
  34 static DEFINE_MUTEX(m41t00_mutex);
  35
  36 static struct i2c_driver m41t00_driver;
  37 static struct i2c_client *save_client;
  38
  39 static unsigned short ignore[] = { I2C_CLIENT_END };
  40 static unsigned short normal_addr[] = { 0x68, I2C_CLIENT_END };
  41
  42 static struct i2c_client_address_data addr_data = {
  43         .normal_i2c             = normal_addr,
  44         .probe                  = ignore,
  45         .ignore                 = ignore,
  46 };
  47
  48 ulong
  49 m41t00_get_rtc_time(void)
  50 {
  51         s32     sec, min, hour, day, mon, year;
  52         s32     sec1, min1, hour1, day1, mon1, year1;
  53         ulong   limit = 10;
  54
  55         sec = min = hour = day = mon = year = 0;
  56         sec1 = min1 = hour1 = day1 = mon1 = year1 = 0;
  57
  58         mutex_lock(&m41t00_mutex);
  59         do {
  60                 if (((sec = i2c_smbus_read_byte_data(save_client, 0)) >= 0)
  61                         && ((min = i2c_smbus_read_byte_data(save_client, 1))
  62                                 >= 0)
  63                         && ((hour = i2c_smbus_read_byte_data(save_client, 2))
  64                                 >= 0)
  65                         && ((day = i2c_smbus_read_byte_data(save_client, 4))
  66                                 >= 0)
  67                         && ((mon = i2c_smbus_read_byte_data(save_client, 5))
  68                                 >= 0)
  69                         && ((year = i2c_smbus_read_byte_data(save_client, 6))
  70                                 >= 0)
  71                         && ((sec == sec1) && (min == min1) && (hour == hour1)
  72                                 && (day == day1) && (mon == mon1)
  73                                 && (year == year1)))
  74
  75                                 break;
  76
  77                 sec1 = sec;
  78                 min1 = min;
  79                 hour1 = hour;
  80                 day1 = day;
  81                 mon1 = mon;
  82                 year1 = year;
  83         } while (--limit > 0);
  84         mutex_unlock(&m41t00_mutex);
  85
  86         if (limit == 0) {
  87                 dev_warn(&save_client->dev,
  88                         "m41t00: can't read rtc chip\n");
  89                 sec = min = hour = day = mon = year = 0;
  90         }
  91
  92         sec &= 0x7f;
  93         min &= 0x7f;
  94         hour &= 0x3f;
  95         day &= 0x3f;
  96         mon &= 0x1f;
  97         year &= 0xff;
  98
  99         BCD_TO_BIN(sec);
 100         BCD_TO_BIN(min);
 101         BCD_TO_BIN(hour);
 102         BCD_TO_BIN(day);
 103         BCD_TO_BIN(mon);
 104         BCD_TO_BIN(year);
 105
 106         year += 1900;
 107         if (year < 1970)
 108                 year += 100;
 109
 110         return mktime(year, mon, day, hour, min, sec);
 111 }
 112
 113 static void
 114 m41t00_set_tlet(ulong arg)
 115 {
 116         struct rtc_time tm;
 117         ulong   nowtime = *(ulong *)arg;
 118
 119         to_tm(nowtime, &tm);
 120         tm.tm_year = (tm.tm_year - 1900) % 100;
 121
 122         BIN_TO_BCD(tm.tm_sec);
 123         BIN_TO_BCD(tm.tm_min);
 124         BIN_TO_BCD(tm.tm_hour);
 125         BIN_TO_BCD(tm.tm_mon);
 126         BIN_TO_BCD(tm.tm_mday);
 127         BIN_TO_BCD(tm.tm_year);
 128
 129         mutex_lock(&m41t00_mutex);
 130         if ((i2c_smbus_write_byte_data(save_client, 0, tm.tm_sec & 0x7f) < 0)
 131                 || (i2c_smbus_write_byte_data(save_client, 1, tm.tm_min & 0x7f)
 132                         < 0)
 133                 || (i2c_smbus_write_byte_data(save_client, 2, tm.tm_hour & 0x7f)
 134                         < 0)
 135                 || (i2c_smbus_write_byte_data(save_client, 4, tm.tm_mday & 0x7f)
 136                         < 0)
 137                 || (i2c_smbus_write_byte_data(save_client, 5, tm.tm_mon & 0x7f)
 138                         < 0)
 139                 || (i2c_smbus_write_byte_data(save_client, 6, tm.tm_year & 0x7f)
 140                         < 0))
 141
 142                 dev_warn(&save_client->dev,"m41t00: can't write to rtc chip\n");
 143
 144         mutex_unlock(&m41t00_mutex);
 145         return;
 146 }
 147
 148 static ulong    new_time;
 149
 150 DECLARE_TASKLET_DISABLED(m41t00_tasklet, m41t00_set_tlet, (ulong)&new_time);
 151
 152 int
 153 m41t00_set_rtc_time(ulong nowtime)
 154 {
 155         new_time = nowtime;
 156
 157         if (in_interrupt())
 158                 tasklet_schedule(&m41t00_tasklet);
 159         else
 160                 m41t00_set_tlet((ulong)&new_time);
 161
 162         return 0;
 163 }
 164
 165 /*
 166  *****************************************************************************
 167  *
 168  *      Driver Interface
 169  *
 170  *****************************************************************************
 171  */
 172 static int
 173 m41t00_probe(struct i2c_adapter *adap, int addr, int kind)
 174 {
 175         struct i2c_client *client;
 176         int rc;
 177
 178         client = kzalloc(sizeof(struct i2c_client), GFP_KERNEL);
 179         if (!client)
 180                 return -ENOMEM;
 181
 182         strncpy(client->name, M41T00_DRV_NAME, I2C_NAME_SIZE);
 183         client->addr = addr;
 184         client->adapter = adap;
 185         client->driver = &m41t00_driver;
 186
 187         if ((rc = i2c_attach_client(client)) != 0) {
 188                 kfree(client);
 189                 return rc;
 190         }
 191
 192         save_client = client;
 193         return 0;
 194 }
 195
 196 static int
 197 m41t00_attach(struct i2c_adapter *adap)
 198 {
 199         return i2c_probe(adap, &addr_data, m41t00_probe);
 200 }
 201
 202 static int
 203 m41t00_detach(struct i2c_client *client)
 204 {
 205         int     rc;
 206
 207         if ((rc = i2c_detach_client(client)) == 0) {
 208                 kfree(client);
 209                 tasklet_kill(&m41t00_tasklet);
 210         }
 211         return rc;
 212 }
 213
 214 static struct i2c_driver m41t00_driver = {
 215         .driver = {
 216                 .name   = M41T00_DRV_NAME,
 217         },
 218         .id             = I2C_DRIVERID_STM41T00,
 219         .attach_adapter = m41t00_attach,
 220         .detach_client  = m41t00_detach,
 221 };
 222
 223 static int __init
 224 m41t00_init(void)
 225 {
 226         return i2c_add_driver(&m41t00_driver);
 227 }
 228
 229 static void __exit
 230 m41t00_exit(void)
 231 {
 232         i2c_del_driver(&m41t00_driver);
 233         return;
 234 }
 235
 236 module_init(m41t00_init);
 237 module_exit(m41t00_exit);
 238
 239 MODULE_AUTHOR("Mark A. Greer <mgreer@mvista.com>");
 240 MODULE_DESCRIPTION("ST Microelectronics M41T00 RTC I2C Client Driver");
 241 MODULE_LICENSE("GPL");