312 lines
7.0 KiB
C
312 lines
7.0 KiB
C
/*
|
|
* rtc class driver for the Maxim MAX6900 chip
|
|
*
|
|
* Author: Dale Farnsworth <dale@farnsworth.org>
|
|
*
|
|
* based on previously existing rtc class drivers
|
|
*
|
|
* 2007 (c) MontaVista, Software, Inc. This file is licensed under
|
|
* the terms of the GNU General Public License version 2. This program
|
|
* is licensed "as is" without any warranty of any kind, whether express
|
|
* or implied.
|
|
*/
|
|
|
|
#include <linux/module.h>
|
|
#include <linux/i2c.h>
|
|
#include <linux/bcd.h>
|
|
#include <linux/rtc.h>
|
|
#include <linux/delay.h>
|
|
|
|
#define DRV_NAME "max6900"
|
|
#define DRV_VERSION "0.1"
|
|
|
|
/*
|
|
* register indices
|
|
*/
|
|
#define MAX6900_REG_SC 0 /* seconds 00-59 */
|
|
#define MAX6900_REG_MN 1 /* minutes 00-59 */
|
|
#define MAX6900_REG_HR 2 /* hours 00-23 */
|
|
#define MAX6900_REG_DT 3 /* day of month 00-31 */
|
|
#define MAX6900_REG_MO 4 /* month 01-12 */
|
|
#define MAX6900_REG_DW 5 /* day of week 1-7 */
|
|
#define MAX6900_REG_YR 6 /* year 00-99 */
|
|
#define MAX6900_REG_CT 7 /* control */
|
|
#define MAX6900_REG_LEN 8
|
|
|
|
#define MAX6900_REG_CT_WP (1 << 7) /* Write Protect */
|
|
|
|
/*
|
|
* register read/write commands
|
|
*/
|
|
#define MAX6900_REG_CONTROL_WRITE 0x8e
|
|
#define MAX6900_REG_BURST_READ 0xbf
|
|
#define MAX6900_REG_BURST_WRITE 0xbe
|
|
#define MAX6900_REG_RESERVED_READ 0x96
|
|
|
|
#define MAX6900_IDLE_TIME_AFTER_WRITE 3 /* specification says 2.5 mS */
|
|
|
|
#define MAX6900_I2C_ADDR 0xa0
|
|
|
|
static unsigned short normal_i2c[] = {
|
|
MAX6900_I2C_ADDR >> 1,
|
|
I2C_CLIENT_END
|
|
};
|
|
|
|
I2C_CLIENT_INSMOD; /* defines addr_data */
|
|
|
|
static int max6900_probe(struct i2c_adapter *adapter, int addr, int kind);
|
|
|
|
static int max6900_i2c_read_regs(struct i2c_client *client, u8 *buf)
|
|
{
|
|
u8 reg_addr[1] = { MAX6900_REG_BURST_READ };
|
|
struct i2c_msg msgs[2] = {
|
|
{
|
|
.addr = client->addr,
|
|
.flags = 0, /* write */
|
|
.len = sizeof(reg_addr),
|
|
.buf = reg_addr
|
|
},
|
|
{
|
|
.addr = client->addr,
|
|
.flags = I2C_M_RD,
|
|
.len = MAX6900_REG_LEN,
|
|
.buf = buf
|
|
}
|
|
};
|
|
int rc;
|
|
|
|
rc = i2c_transfer(client->adapter, msgs, ARRAY_SIZE(msgs));
|
|
if (rc != ARRAY_SIZE(msgs)) {
|
|
dev_err(&client->dev, "%s: register read failed\n",
|
|
__FUNCTION__);
|
|
return -EIO;
|
|
}
|
|
return 0;
|
|
}
|
|
|
|
static int max6900_i2c_write_regs(struct i2c_client *client, u8 const *buf)
|
|
{
|
|
u8 i2c_buf[MAX6900_REG_LEN + 1] = { MAX6900_REG_BURST_WRITE };
|
|
struct i2c_msg msgs[1] = {
|
|
{
|
|
.addr = client->addr,
|
|
.flags = 0, /* write */
|
|
.len = MAX6900_REG_LEN + 1,
|
|
.buf = i2c_buf
|
|
}
|
|
};
|
|
int rc;
|
|
|
|
memcpy(&i2c_buf[1], buf, MAX6900_REG_LEN);
|
|
|
|
rc = i2c_transfer(client->adapter, msgs, ARRAY_SIZE(msgs));
|
|
if (rc != ARRAY_SIZE(msgs)) {
|
|
dev_err(&client->dev, "%s: register write failed\n",
|
|
__FUNCTION__);
|
|
return -EIO;
|
|
}
|
|
msleep(MAX6900_IDLE_TIME_AFTER_WRITE);
|
|
return 0;
|
|
}
|
|
|
|
static int max6900_i2c_validate_client(struct i2c_client *client)
|
|
{
|
|
u8 regs[MAX6900_REG_LEN];
|
|
u8 zero_mask[MAX6900_REG_LEN] = {
|
|
0x80, /* seconds */
|
|
0x80, /* minutes */
|
|
0x40, /* hours */
|
|
0xc0, /* day of month */
|
|
0xe0, /* month */
|
|
0xf8, /* day of week */
|
|
0x00, /* year */
|
|
0x7f, /* control */
|
|
};
|
|
int i;
|
|
int rc;
|
|
int reserved;
|
|
|
|
reserved = i2c_smbus_read_byte_data(client, MAX6900_REG_RESERVED_READ);
|
|
if (reserved != 0x07)
|
|
return -ENODEV;
|
|
|
|
rc = max6900_i2c_read_regs(client, regs);
|
|
if (rc < 0)
|
|
return rc;
|
|
|
|
for (i = 0; i < MAX6900_REG_LEN; ++i) {
|
|
if (regs[i] & zero_mask[i])
|
|
return -ENODEV;
|
|
}
|
|
|
|
return 0;
|
|
}
|
|
|
|
static int max6900_i2c_read_time(struct i2c_client *client, struct rtc_time *tm)
|
|
{
|
|
int rc;
|
|
u8 regs[MAX6900_REG_LEN];
|
|
|
|
rc = max6900_i2c_read_regs(client, regs);
|
|
if (rc < 0)
|
|
return rc;
|
|
|
|
tm->tm_sec = BCD2BIN(regs[MAX6900_REG_SC]);
|
|
tm->tm_min = BCD2BIN(regs[MAX6900_REG_MN]);
|
|
tm->tm_hour = BCD2BIN(regs[MAX6900_REG_HR] & 0x3f);
|
|
tm->tm_mday = BCD2BIN(regs[MAX6900_REG_DT]);
|
|
tm->tm_mon = BCD2BIN(regs[MAX6900_REG_MO]) - 1;
|
|
tm->tm_year = BCD2BIN(regs[MAX6900_REG_YR]) + 100;
|
|
tm->tm_wday = BCD2BIN(regs[MAX6900_REG_DW]);
|
|
|
|
return 0;
|
|
}
|
|
|
|
static int max6900_i2c_clear_write_protect(struct i2c_client *client)
|
|
{
|
|
int rc;
|
|
rc = i2c_smbus_write_byte_data (client, MAX6900_REG_CONTROL_WRITE, 0);
|
|
if (rc < 0) {
|
|
dev_err(&client->dev, "%s: control register write failed\n",
|
|
__FUNCTION__);
|
|
return -EIO;
|
|
}
|
|
return 0;
|
|
}
|
|
|
|
static int max6900_i2c_set_time(struct i2c_client *client,
|
|
struct rtc_time const *tm)
|
|
{
|
|
u8 regs[MAX6900_REG_LEN];
|
|
int rc;
|
|
|
|
rc = max6900_i2c_clear_write_protect(client);
|
|
if (rc < 0)
|
|
return rc;
|
|
|
|
regs[MAX6900_REG_SC] = BIN2BCD(tm->tm_sec);
|
|
regs[MAX6900_REG_MN] = BIN2BCD(tm->tm_min);
|
|
regs[MAX6900_REG_HR] = BIN2BCD(tm->tm_hour);
|
|
regs[MAX6900_REG_DT] = BIN2BCD(tm->tm_mday);
|
|
regs[MAX6900_REG_MO] = BIN2BCD(tm->tm_mon + 1);
|
|
regs[MAX6900_REG_YR] = BIN2BCD(tm->tm_year - 100);
|
|
regs[MAX6900_REG_DW] = BIN2BCD(tm->tm_wday);
|
|
regs[MAX6900_REG_CT] = MAX6900_REG_CT_WP; /* set write protect */
|
|
|
|
rc = max6900_i2c_write_regs(client, regs);
|
|
if (rc < 0)
|
|
return rc;
|
|
|
|
return 0;
|
|
}
|
|
|
|
static int max6900_rtc_read_time(struct device *dev, struct rtc_time *tm)
|
|
{
|
|
return max6900_i2c_read_time(to_i2c_client(dev), tm);
|
|
}
|
|
|
|
static int max6900_rtc_set_time(struct device *dev, struct rtc_time *tm)
|
|
{
|
|
return max6900_i2c_set_time(to_i2c_client(dev), tm);
|
|
}
|
|
|
|
static int max6900_attach_adapter(struct i2c_adapter *adapter)
|
|
{
|
|
return i2c_probe(adapter, &addr_data, max6900_probe);
|
|
}
|
|
|
|
static int max6900_detach_client(struct i2c_client *client)
|
|
{
|
|
struct rtc_device *const rtc = i2c_get_clientdata(client);
|
|
|
|
if (rtc)
|
|
rtc_device_unregister(rtc);
|
|
|
|
return i2c_detach_client(client);
|
|
}
|
|
|
|
static struct i2c_driver max6900_driver = {
|
|
.driver = {
|
|
.name = DRV_NAME,
|
|
},
|
|
.id = I2C_DRIVERID_MAX6900,
|
|
.attach_adapter = max6900_attach_adapter,
|
|
.detach_client = max6900_detach_client,
|
|
};
|
|
|
|
static const struct rtc_class_ops max6900_rtc_ops = {
|
|
.read_time = max6900_rtc_read_time,
|
|
.set_time = max6900_rtc_set_time,
|
|
};
|
|
|
|
static int max6900_probe(struct i2c_adapter *adapter, int addr, int kind)
|
|
{
|
|
int rc = 0;
|
|
struct i2c_client *client = NULL;
|
|
struct rtc_device *rtc = NULL;
|
|
|
|
if (!i2c_check_functionality(adapter, I2C_FUNC_I2C)) {
|
|
rc = -ENODEV;
|
|
goto failout;
|
|
}
|
|
|
|
client = kzalloc(sizeof(struct i2c_client), GFP_KERNEL);
|
|
if (client == NULL) {
|
|
rc = -ENOMEM;
|
|
goto failout;
|
|
}
|
|
|
|
client->addr = addr;
|
|
client->adapter = adapter;
|
|
client->driver = &max6900_driver;
|
|
strlcpy(client->name, DRV_NAME, I2C_NAME_SIZE);
|
|
|
|
if (kind < 0) {
|
|
rc = max6900_i2c_validate_client(client);
|
|
if (rc < 0)
|
|
goto failout;
|
|
}
|
|
|
|
rc = i2c_attach_client(client);
|
|
if (rc < 0)
|
|
goto failout;
|
|
|
|
dev_info(&client->dev,
|
|
"chip found, driver version " DRV_VERSION "\n");
|
|
|
|
rtc = rtc_device_register(max6900_driver.driver.name,
|
|
&client->dev,
|
|
&max6900_rtc_ops, THIS_MODULE);
|
|
if (IS_ERR(rtc)) {
|
|
rc = PTR_ERR(rtc);
|
|
goto failout_detach;
|
|
}
|
|
|
|
i2c_set_clientdata(client, rtc);
|
|
|
|
return 0;
|
|
|
|
failout_detach:
|
|
i2c_detach_client(client);
|
|
failout:
|
|
kfree(client);
|
|
return rc;
|
|
}
|
|
|
|
static int __init max6900_init(void)
|
|
{
|
|
return i2c_add_driver(&max6900_driver);
|
|
}
|
|
|
|
static void __exit max6900_exit(void)
|
|
{
|
|
i2c_del_driver(&max6900_driver);
|
|
}
|
|
|
|
MODULE_DESCRIPTION("Maxim MAX6900 RTC driver");
|
|
MODULE_LICENSE("GPL");
|
|
MODULE_VERSION(DRV_VERSION);
|
|
|
|
module_init(max6900_init);
|
|
module_exit(max6900_exit);
|