2 * linux/drivers/i2c/chips/ds1337.c
4 * Copyright (C) 2005 James Chapman <jchapman@katalix.com>
6 * based on linux/drivers/acorn/char/pcf8583.c
7 * Copyright (C) 2000 Russell King
9 * This program is free software; you can redistribute it and/or modify
10 * it under the terms of the GNU General Public License version 2 as
11 * published by the Free Software Foundation.
13 * Driver for Dallas Semiconductor DS1337 and DS1339 real time clock chip
16 #include <linux/module.h>
17 #include <linux/init.h>
18 #include <linux/slab.h>
19 #include <linux/i2c.h>
20 #include <linux/string.h>
21 #include <linux/rtc.h> /* get the user-level API */
22 #include <linux/bcd.h>
23 #include <linux/list.h>
25 /* Device registers */
26 #define DS1337_REG_HOUR 2
27 #define DS1337_REG_DAY 3
28 #define DS1337_REG_DATE 4
29 #define DS1337_REG_MONTH 5
30 #define DS1337_REG_CONTROL 14
31 #define DS1337_REG_STATUS 15
33 /* FIXME - how do we export these interface constants? */
34 #define DS1337_GET_DATE 0
35 #define DS1337_SET_DATE 1
38 * Functions declaration
40 static unsigned short normal_i2c[] = { 0x68, I2C_CLIENT_END };
42 I2C_CLIENT_INSMOD_1(ds1337);
44 static int ds1337_attach_adapter(struct i2c_adapter *adapter);
45 static int ds1337_detect(struct i2c_adapter *adapter, int address, int kind);
46 static void ds1337_init_client(struct i2c_client *client);
47 static int ds1337_detach_client(struct i2c_client *client);
48 static int ds1337_command(struct i2c_client *client, unsigned int cmd,
52 * Driver data (common to all clients)
54 static struct i2c_driver ds1337_driver = {
57 .attach_adapter = ds1337_attach_adapter,
58 .detach_client = ds1337_detach_client,
59 .command = ds1337_command,
63 * Client data (each client gets its own)
66 struct i2c_client client;
67 struct list_head list;
73 static LIST_HEAD(ds1337_clients);
75 static inline int ds1337_read(struct i2c_client *client, u8 reg, u8 *value)
77 s32 tmp = i2c_smbus_read_byte_data(client, reg);
88 * Chip access functions
90 static int ds1337_get_datetime(struct i2c_client *client, struct rtc_time *dt)
95 struct i2c_msg msg[2];
99 dev_dbg(&client->dev, "%s: EINVAL: dt=NULL\n", __FUNCTION__);
103 msg[0].addr = client->addr;
108 msg[1].addr = client->addr;
109 msg[1].flags = I2C_M_RD;
110 msg[1].len = sizeof(buf);
111 msg[1].buf = &buf[0];
113 result = i2c_transfer(client->adapter, msg, 2);
115 dev_dbg(&client->dev, "%s: [%d] %02x %02x %02x %02x %02x %02x %02x\n",
116 __FUNCTION__, result, buf[0], buf[1], buf[2], buf[3],
117 buf[4], buf[5], buf[6]);
120 dt->tm_sec = BCD2BIN(buf[0]);
121 dt->tm_min = BCD2BIN(buf[1]);
123 dt->tm_hour = BCD2BIN(val);
124 dt->tm_wday = BCD2BIN(buf[3]) - 1;
125 dt->tm_mday = BCD2BIN(buf[4]);
127 dt->tm_mon = BCD2BIN(val) - 1;
128 dt->tm_year = BCD2BIN(buf[6]);
132 dev_dbg(&client->dev, "%s: secs=%d, mins=%d, "
133 "hours=%d, mday=%d, mon=%d, year=%d, wday=%d\n",
134 __FUNCTION__, dt->tm_sec, dt->tm_min,
135 dt->tm_hour, dt->tm_mday,
136 dt->tm_mon, dt->tm_year, dt->tm_wday);
141 dev_err(&client->dev, "error reading data! %d\n", result);
145 static int ds1337_set_datetime(struct i2c_client *client, struct rtc_time *dt)
150 struct i2c_msg msg[1];
153 dev_dbg(&client->dev, "%s: EINVAL: dt=NULL\n", __FUNCTION__);
157 dev_dbg(&client->dev, "%s: secs=%d, mins=%d, hours=%d, "
158 "mday=%d, mon=%d, year=%d, wday=%d\n", __FUNCTION__,
159 dt->tm_sec, dt->tm_min, dt->tm_hour,
160 dt->tm_mday, dt->tm_mon, dt->tm_year, dt->tm_wday);
162 buf[0] = 0; /* reg offset */
163 buf[1] = BIN2BCD(dt->tm_sec);
164 buf[2] = BIN2BCD(dt->tm_min);
165 buf[3] = BIN2BCD(dt->tm_hour);
166 buf[4] = BIN2BCD(dt->tm_wday + 1);
167 buf[5] = BIN2BCD(dt->tm_mday);
168 buf[6] = BIN2BCD(dt->tm_mon + 1);
174 buf[7] = BIN2BCD(val);
176 msg[0].addr = client->addr;
178 msg[0].len = sizeof(buf);
179 msg[0].buf = &buf[0];
181 result = i2c_transfer(client->adapter, msg, 1);
185 dev_err(&client->dev, "error writing data! %d\n", result);
189 static int ds1337_command(struct i2c_client *client, unsigned int cmd,
192 dev_dbg(&client->dev, "%s: cmd=%d\n", __FUNCTION__, cmd);
195 case DS1337_GET_DATE:
196 return ds1337_get_datetime(client, arg);
198 case DS1337_SET_DATE:
199 return ds1337_set_datetime(client, arg);
207 * Public API for access to specific device. Useful for low-level
208 * RTC access from kernel code.
210 int ds1337_do_command(int bus, int cmd, void *arg)
212 struct list_head *walk;
213 struct list_head *tmp;
214 struct ds1337_data *data;
216 list_for_each_safe(walk, tmp, &ds1337_clients) {
217 data = list_entry(walk, struct ds1337_data, list);
218 if (data->client.adapter->nr == bus)
219 return ds1337_command(&data->client, cmd, arg);
225 static int ds1337_attach_adapter(struct i2c_adapter *adapter)
227 return i2c_probe(adapter, &addr_data, ds1337_detect);
231 * The following function does more than just detection. If detection
232 * succeeds, it also registers the new chip.
234 static int ds1337_detect(struct i2c_adapter *adapter, int address, int kind)
236 struct i2c_client *new_client;
237 struct ds1337_data *data;
239 const char *name = "";
241 if (!i2c_check_functionality(adapter, I2C_FUNC_SMBUS_BYTE_DATA |
245 if (!(data = kzalloc(sizeof(struct ds1337_data), GFP_KERNEL))) {
249 INIT_LIST_HEAD(&data->list);
251 /* The common I2C client data is placed right before the
252 * DS1337-specific data.
254 new_client = &data->client;
255 i2c_set_clientdata(new_client, data);
256 new_client->addr = address;
257 new_client->adapter = adapter;
258 new_client->driver = &ds1337_driver;
259 new_client->flags = 0;
262 * Now we do the remaining detection. A negative kind means that
263 * the driver was loaded with no force parameter (default), so we
264 * must both detect and identify the chip. A zero kind means that
265 * the driver was loaded with the force parameter, the detection
266 * step shall be skipped. A positive kind means that the driver
267 * was loaded with the force parameter and a given kind of chip is
268 * requested, so both the detection and the identification steps
271 * For detection, we read registers that are most likely to cause
272 * detection failure, i.e. those that have more bits with fixed
273 * or reserved values.
276 /* Default to an DS1337 if forced */
280 if (kind < 0) { /* detection and identification */
283 /* Check that status register bits 6-2 are zero */
284 if ((ds1337_read(new_client, DS1337_REG_STATUS, &data) < 0) ||
288 /* Check for a valid day register value */
289 if ((ds1337_read(new_client, DS1337_REG_DAY, &data) < 0) ||
290 (data == 0) || (data & 0xf8))
293 /* Check for a valid date register value */
294 if ((ds1337_read(new_client, DS1337_REG_DATE, &data) < 0) ||
295 (data == 0) || (data & 0xc0) || ((data & 0x0f) > 9) ||
299 /* Check for a valid month register value */
300 if ((ds1337_read(new_client, DS1337_REG_MONTH, &data) < 0) ||
301 (data == 0) || (data & 0x60) || ((data & 0x0f) > 9) ||
302 ((data >= 0x13) && (data <= 0x19)))
305 /* Check that control register bits 6-5 are zero */
306 if ((ds1337_read(new_client, DS1337_REG_CONTROL, &data) < 0) ||
316 /* We can fill in the remaining client fields */
317 strlcpy(new_client->name, name, I2C_NAME_SIZE);
319 /* Tell the I2C layer a new client has arrived */
320 if ((err = i2c_attach_client(new_client)))
323 /* Initialize the DS1337 chip */
324 ds1337_init_client(new_client);
326 /* Add client to local list */
327 list_add(&data->list, &ds1337_clients);
337 static void ds1337_init_client(struct i2c_client *client)
341 /* On some boards, the RTC isn't configured by boot firmware.
342 * Handle that case by starting/configuring the RTC now.
344 status = i2c_smbus_read_byte_data(client, DS1337_REG_STATUS);
345 control = i2c_smbus_read_byte_data(client, DS1337_REG_CONTROL);
347 if ((status & 0x80) || (control & 0x80)) {
348 /* RTC not running */
350 struct i2c_msg msg[1];
352 dev_dbg(&client->dev, "%s: RTC not running!\n", __FUNCTION__);
354 /* Initialize all, including STATUS and CONTROL to zero */
355 memset(buf, 0, sizeof(buf));
356 msg[0].addr = client->addr;
358 msg[0].len = sizeof(buf);
359 msg[0].buf = &buf[0];
361 i2c_transfer(client->adapter, msg, 1);
363 /* Running: ensure that device is set in 24-hour mode */
366 val = i2c_smbus_read_byte_data(client, DS1337_REG_HOUR);
367 if ((val >= 0) && (val & (1 << 6)))
368 i2c_smbus_write_byte_data(client, DS1337_REG_HOUR,
373 static int ds1337_detach_client(struct i2c_client *client)
376 struct ds1337_data *data = i2c_get_clientdata(client);
378 if ((err = i2c_detach_client(client)))
381 list_del(&data->list);
386 static int __init ds1337_init(void)
388 return i2c_add_driver(&ds1337_driver);
391 static void __exit ds1337_exit(void)
393 i2c_del_driver(&ds1337_driver);
396 MODULE_AUTHOR("James Chapman <jchapman@katalix.com>");
397 MODULE_DESCRIPTION("DS1337 RTC driver");
398 MODULE_LICENSE("GPL");
400 EXPORT_SYMBOL_GPL(ds1337_do_command);
402 module_init(ds1337_init);
403 module_exit(ds1337_exit);