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authorRandy Vinson <rvinson@mvista.com>2005-06-03 17:36:06 -0400
committerGreg Kroah-Hartman <gregkh@suse.de>2005-06-22 00:52:06 -0400
commitc124a78d8c7475ecc43f385f34112b638c4228d9 (patch)
tree46de795c5e2da258a54501658f74e9619c271527 /drivers/i2c
parent69dd204b6b45987dbf9ce7058cd238d355865281 (diff)
[PATCH] I2C: Add support for Maxim/Dallas DS1374 Real-Time Clock Chip (1/2)
Add support for Maxim/Dallas DS1374 Real-Time Clock Chip This change adds support for the Maxim/Dallas DS1374 RTC chip. This chip is an I2C-based RTC that maintains a simple 32-bit binary seconds count with battery backup support. Signed-off-by: Randy Vinson <rvinson@mvista.com> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
Diffstat (limited to 'drivers/i2c')
-rw-r--r--drivers/i2c/chips/Kconfig11
-rw-r--r--drivers/i2c/chips/Makefile1
-rw-r--r--drivers/i2c/chips/ds1374.c266
3 files changed, 278 insertions, 0 deletions
diff --git a/drivers/i2c/chips/Kconfig b/drivers/i2c/chips/Kconfig
index 33de80afd6c6..a0982da09803 100644
--- a/drivers/i2c/chips/Kconfig
+++ b/drivers/i2c/chips/Kconfig
@@ -417,6 +417,17 @@ config SENSORS_DS1337
417 This driver can also be built as a module. If so, the module 417 This driver can also be built as a module. If so, the module
418 will be called ds1337. 418 will be called ds1337.
419 419
420config SENSORS_DS1374
421 tristate "Maxim/Dallas Semiconductor DS1374 Real Time Clock"
422 depends on I2C && EXPERIMENTAL
423 select I2C_SENSOR
424 help
425 If you say yes here you get support for Dallas Semiconductor
426 DS1374 real-time clock chips.
427
428 This driver can also be built as a module. If so, the module
429 will be called ds1374.
430
420config SENSORS_EEPROM 431config SENSORS_EEPROM
421 tristate "EEPROM reader" 432 tristate "EEPROM reader"
422 depends on I2C && EXPERIMENTAL 433 depends on I2C && EXPERIMENTAL
diff --git a/drivers/i2c/chips/Makefile b/drivers/i2c/chips/Makefile
index 6bebdc104166..b5e6d2f84f97 100644
--- a/drivers/i2c/chips/Makefile
+++ b/drivers/i2c/chips/Makefile
@@ -14,6 +14,7 @@ obj-$(CONFIG_SENSORS_ADM1031) += adm1031.o
14obj-$(CONFIG_SENSORS_ADM9240) += adm9240.o 14obj-$(CONFIG_SENSORS_ADM9240) += adm9240.o
15obj-$(CONFIG_SENSORS_ATXP1) += atxp1.o 15obj-$(CONFIG_SENSORS_ATXP1) += atxp1.o
16obj-$(CONFIG_SENSORS_DS1337) += ds1337.o 16obj-$(CONFIG_SENSORS_DS1337) += ds1337.o
17obj-$(CONFIG_SENSORS_DS1374) += ds1374.o
17obj-$(CONFIG_SENSORS_DS1621) += ds1621.o 18obj-$(CONFIG_SENSORS_DS1621) += ds1621.o
18obj-$(CONFIG_SENSORS_EEPROM) += eeprom.o 19obj-$(CONFIG_SENSORS_EEPROM) += eeprom.o
19obj-$(CONFIG_SENSORS_FSCHER) += fscher.o 20obj-$(CONFIG_SENSORS_FSCHER) += fscher.o
diff --git a/drivers/i2c/chips/ds1374.c b/drivers/i2c/chips/ds1374.c
new file mode 100644
index 000000000000..1278d979db2b
--- /dev/null
+++ b/drivers/i2c/chips/ds1374.c
@@ -0,0 +1,266 @@
1/*
2 * drivers/i2c/chips/ds1374.c
3 *
4 * I2C client/driver for the Maxim/Dallas DS1374 Real-Time Clock
5 *
6 * Author: Randy Vinson <rvinson@mvista.com>
7 *
8 * Based on the m41t00.c by Mark Greer <mgreer@mvista.com>
9 *
10 * 2005 (c) MontaVista Software, Inc. This file is licensed under
11 * the terms of the GNU General Public License version 2. This program
12 * is licensed "as is" without any warranty of any kind, whether express
13 * or implied.
14 */
15/*
16 * This i2c client/driver wedges between the drivers/char/genrtc.c RTC
17 * interface and the SMBus interface of the i2c subsystem.
18 * It would be more efficient to use i2c msgs/i2c_transfer directly but, as
19 * recommened in .../Documentation/i2c/writing-clients section
20 * "Sending and receiving", using SMBus level communication is preferred.
21 */
22
23#include <linux/kernel.h>
24#include <linux/module.h>
25#include <linux/interrupt.h>
26#include <linux/i2c.h>
27#include <linux/rtc.h>
28#include <linux/bcd.h>
29
30#include <asm/time.h>
31#include <asm/rtc.h>
32
33#define DS1374_REG_TOD0 0x00
34#define DS1374_REG_TOD1 0x01
35#define DS1374_REG_TOD2 0x02
36#define DS1374_REG_TOD3 0x03
37#define DS1374_REG_WDALM0 0x04
38#define DS1374_REG_WDALM1 0x05
39#define DS1374_REG_WDALM2 0x06
40#define DS1374_REG_CR 0x07
41#define DS1374_REG_SR 0x08
42#define DS1374_REG_SR_OSF 0x80
43#define DS1374_REG_TCR 0x09
44
45#define DS1374_DRV_NAME "ds1374"
46
47static DECLARE_MUTEX(ds1374_mutex);
48
49static struct i2c_driver ds1374_driver;
50static struct i2c_client *save_client;
51
52static unsigned short ignore[] = { I2C_CLIENT_END };
53static unsigned short normal_addr[] = { 0x68, I2C_CLIENT_END };
54
55static struct i2c_client_address_data addr_data = {
56 .normal_i2c = normal_addr,
57 .normal_i2c_range = ignore,
58 .probe = ignore,
59 .probe_range = ignore,
60 .ignore = ignore,
61 .ignore_range = ignore,
62 .force = ignore,
63};
64
65static ulong ds1374_read_rtc(void)
66{
67 ulong time = 0;
68 int reg = DS1374_REG_WDALM0;
69
70 while (reg--) {
71 s32 tmp;
72 if ((tmp = i2c_smbus_read_byte_data(save_client, reg)) < 0) {
73 dev_warn(&save_client->dev,
74 "can't read from rtc chip\n");
75 return 0;
76 }
77 time = (time << 8) | (tmp & 0xff);
78 }
79 return time;
80}
81
82static void ds1374_write_rtc(ulong time)
83{
84 int reg;
85
86 for (reg = DS1374_REG_TOD0; reg < DS1374_REG_WDALM0; reg++) {
87 if (i2c_smbus_write_byte_data(save_client, reg, time & 0xff)
88 < 0) {
89 dev_warn(&save_client->dev,
90 "can't write to rtc chip\n");
91 break;
92 }
93 time = time >> 8;
94 }
95}
96
97static void ds1374_check_rtc_status(void)
98{
99 s32 tmp;
100
101 tmp = i2c_smbus_read_byte_data(save_client, DS1374_REG_SR);
102 if (tmp < 0) {
103 dev_warn(&save_client->dev,
104 "can't read status from rtc chip\n");
105 return;
106 }
107 if (tmp & DS1374_REG_SR_OSF) {
108 dev_warn(&save_client->dev,
109 "oscillator discontinuity flagged, time unreliable\n");
110 tmp &= ~DS1374_REG_SR_OSF;
111 tmp = i2c_smbus_write_byte_data(save_client, DS1374_REG_SR,
112 tmp & 0xff);
113 if (tmp < 0)
114 dev_warn(&save_client->dev,
115 "can't clear discontinuity notification\n");
116 }
117}
118
119ulong ds1374_get_rtc_time(void)
120{
121 ulong t1, t2;
122 int limit = 10; /* arbitrary retry limit */
123
124 down(&ds1374_mutex);
125
126 /*
127 * Since the reads are being performed one byte at a time using
128 * the SMBus vs a 4-byte i2c transfer, there is a chance that a
129 * carry will occur during the read. To detect this, 2 reads are
130 * performed and compared.
131 */
132 do {
133 t1 = ds1374_read_rtc();
134 t2 = ds1374_read_rtc();
135 } while (t1 != t2 && limit--);
136
137 up(&ds1374_mutex);
138
139 if (t1 != t2) {
140 dev_warn(&save_client->dev,
141 "can't get consistent time from rtc chip\n");
142 t1 = 0;
143 }
144
145 return t1;
146}
147
148static void ds1374_set_tlet(ulong arg)
149{
150 ulong t1, t2;
151 int limit = 10; /* arbitrary retry limit */
152
153 t1 = *(ulong *) arg;
154
155 down(&ds1374_mutex);
156
157 /*
158 * Since the writes are being performed one byte at a time using
159 * the SMBus vs a 4-byte i2c transfer, there is a chance that a
160 * carry will occur during the write. To detect this, the write
161 * value is read back and compared.
162 */
163 do {
164 ds1374_write_rtc(t1);
165 t2 = ds1374_read_rtc();
166 } while (t1 != t2 && limit--);
167
168 up(&ds1374_mutex);
169
170 if (t1 != t2)
171 dev_warn(&save_client->dev,
172 "can't confirm time set from rtc chip\n");
173}
174
175ulong new_time;
176
177DECLARE_TASKLET_DISABLED(ds1374_tasklet, ds1374_set_tlet, (ulong) & new_time);
178
179int ds1374_set_rtc_time(ulong nowtime)
180{
181 new_time = nowtime;
182
183 if (in_interrupt())
184 tasklet_schedule(&ds1374_tasklet);
185 else
186 ds1374_set_tlet((ulong) & new_time);
187
188 return 0;
189}
190
191/*
192 *****************************************************************************
193 *
194 * Driver Interface
195 *
196 *****************************************************************************
197 */
198static int ds1374_probe(struct i2c_adapter *adap, int addr, int kind)
199{
200 struct i2c_client *client;
201 int rc;
202
203 client = kmalloc(sizeof(struct i2c_client), GFP_KERNEL);
204 if (!client)
205 return -ENOMEM;
206
207 memset(client, 0, sizeof(struct i2c_client));
208 strncpy(client->name, DS1374_DRV_NAME, I2C_NAME_SIZE);
209 client->flags = I2C_DF_NOTIFY;
210 client->addr = addr;
211 client->adapter = adap;
212 client->driver = &ds1374_driver;
213
214 if ((rc = i2c_attach_client(client)) != 0) {
215 kfree(client);
216 return rc;
217 }
218
219 save_client = client;
220
221 ds1374_check_rtc_status();
222
223 return 0;
224}
225
226static int ds1374_attach(struct i2c_adapter *adap)
227{
228 return i2c_probe(adap, &addr_data, ds1374_probe);
229}
230
231static int ds1374_detach(struct i2c_client *client)
232{
233 int rc;
234
235 if ((rc = i2c_detach_client(client)) == 0) {
236 kfree(i2c_get_clientdata(client));
237 tasklet_kill(&ds1374_tasklet);
238 }
239 return rc;
240}
241
242static struct i2c_driver ds1374_driver = {
243 .owner = THIS_MODULE,
244 .name = DS1374_DRV_NAME,
245 .id = I2C_DRIVERID_DS1374,
246 .flags = I2C_DF_NOTIFY,
247 .attach_adapter = ds1374_attach,
248 .detach_client = ds1374_detach,
249};
250
251static int __init ds1374_init(void)
252{
253 return i2c_add_driver(&ds1374_driver);
254}
255
256static void __exit ds1374_exit(void)
257{
258 i2c_del_driver(&ds1374_driver);
259}
260
261module_init(ds1374_init);
262module_exit(ds1374_exit);
263
264MODULE_AUTHOR("Randy Vinson <rvinson@mvista.com>");
265MODULE_DESCRIPTION("Maxim/Dallas DS1374 RTC I2C Client Driver");
266MODULE_LICENSE("GPL");