diff options
Diffstat (limited to 'drivers/rtc/rtc-ds3232.c')
| -rw-r--r-- | drivers/rtc/rtc-ds3232.c | 326 |
1 files changed, 326 insertions, 0 deletions
diff --git a/drivers/rtc/rtc-ds3232.c b/drivers/rtc/rtc-ds3232.c new file mode 100644 index 000000000000..9daed8db83d3 --- /dev/null +++ b/drivers/rtc/rtc-ds3232.c @@ -0,0 +1,326 @@ +/* + * RTC client/driver for the Maxim/Dallas DS3232 Real-Time Clock over I2C + * + * Copyright (C) 2009-2010 Freescale Semiconductor. + * + * This program is free software; you can redistribute it and/or modify it + * under the terms of the GNU General Public License as published by the + * Free Software Foundation; either version 2 of the License, or (at your + * option) any later version. + */ +/* + * It would be more efficient to use i2c msgs/i2c_transfer directly but, as + * recommened in .../Documentation/i2c/writing-clients section + * "Sending and receiving", using SMBus level communication is preferred. + */ + +#include <linux/kernel.h> +#include <linux/module.h> +#include <linux/interrupt.h> +#include <linux/i2c.h> +#include <linux/rtc.h> +#include <linux/bcd.h> +#include <linux/workqueue.h> +#include <linux/slab.h> + +#define DS3232_REG_SECONDS 0x00 +#define DS3232_REG_MINUTES 0x01 +#define DS3232_REG_HOURS 0x02 +#define DS3232_REG_AMPM 0x02 +#define DS3232_REG_DAY 0x03 +#define DS3232_REG_DATE 0x04 +#define DS3232_REG_MONTH 0x05 +#define DS3232_REG_CENTURY 0x05 +#define DS3232_REG_YEAR 0x06 +#define DS3232_REG_ALARM1 0x07 /* Alarm 1 BASE */ +#define DS3232_REG_ALARM2 0x0B /* Alarm 2 BASE */ +#define DS3232_REG_CR 0x0E /* Control register */ +# define DS3232_REG_CR_nEOSC 0x80 +# define DS3232_REG_CR_INTCN 0x04 +# define DS3232_REG_CR_A2IE 0x02 +# define DS3232_REG_CR_A1IE 0x01 + +#define DS3232_REG_SR 0x0F /* control/status register */ +# define DS3232_REG_SR_OSF 0x80 +# define DS3232_REG_SR_BSY 0x04 +# define DS3232_REG_SR_A2F 0x02 +# define DS3232_REG_SR_A1F 0x01 + +struct ds3232 { + struct i2c_client *client; + struct rtc_device *rtc; + struct work_struct work; + + /* The mutex protects alarm operations, and prevents a race + * between the enable_irq() in the workqueue and the free_irq() + * in the remove function. + */ + struct mutex mutex; + int exiting; +}; + +static struct i2c_driver ds3232_driver; + +static int ds3232_check_rtc_status(struct i2c_client *client) +{ + int ret = 0; + int control, stat; + + stat = i2c_smbus_read_byte_data(client, DS3232_REG_SR); + if (stat < 0) + return stat; + + if (stat & DS3232_REG_SR_OSF) + dev_warn(&client->dev, + "oscillator discontinuity flagged, " + "time unreliable\n"); + + stat &= ~(DS3232_REG_SR_OSF | DS3232_REG_SR_A1F | DS3232_REG_SR_A2F); + + ret = i2c_smbus_write_byte_data(client, DS3232_REG_SR, stat); + if (ret < 0) + return ret; + + /* If the alarm is pending, clear it before requesting + * the interrupt, so an interrupt event isn't reported + * before everything is initialized. + */ + + control = i2c_smbus_read_byte_data(client, DS3232_REG_CR); + if (control < 0) + return control; + + control &= ~(DS3232_REG_CR_A1IE | DS3232_REG_CR_A2IE); + control |= DS3232_REG_CR_INTCN; + + return i2c_smbus_write_byte_data(client, DS3232_REG_CR, control); +} + +static int ds3232_read_time(struct device *dev, struct rtc_time *time) +{ + struct i2c_client *client = to_i2c_client(dev); + int ret; + u8 buf[7]; + unsigned int year, month, day, hour, minute, second; + unsigned int week, twelve_hr, am_pm; + unsigned int century, add_century = 0; + + ret = i2c_smbus_read_i2c_block_data(client, DS3232_REG_SECONDS, 7, buf); + + if (ret < 0) + return ret; + if (ret < 7) + return -EIO; + + second = buf[0]; + minute = buf[1]; + hour = buf[2]; + week = buf[3]; + day = buf[4]; + month = buf[5]; + year = buf[6]; + + /* Extract additional information for AM/PM and century */ + + twelve_hr = hour & 0x40; + am_pm = hour & 0x20; + century = month & 0x80; + + /* Write to rtc_time structure */ + + time->tm_sec = bcd2bin(second); + time->tm_min = bcd2bin(minute); + if (twelve_hr) { + /* Convert to 24 hr */ + if (am_pm) + time->tm_hour = bcd2bin(hour & 0x1F) + 12; + else + time->tm_hour = bcd2bin(hour & 0x1F); + } else { + time->tm_hour = bcd2bin(hour); + } + + time->tm_wday = bcd2bin(week); + time->tm_mday = bcd2bin(day); + time->tm_mon = bcd2bin(month & 0x7F); + if (century) + add_century = 100; + + time->tm_year = bcd2bin(year) + add_century; + + return rtc_valid_tm(time); +} + +static int ds3232_set_time(struct device *dev, struct rtc_time *time) +{ + struct i2c_client *client = to_i2c_client(dev); + u8 buf[7]; + + /* Extract time from rtc_time and load into ds3232*/ + + buf[0] = bin2bcd(time->tm_sec); + buf[1] = bin2bcd(time->tm_min); + buf[2] = bin2bcd(time->tm_hour); + buf[3] = bin2bcd(time->tm_wday); /* Day of the week */ + buf[4] = bin2bcd(time->tm_mday); /* Date */ + buf[5] = bin2bcd(time->tm_mon); + if (time->tm_year >= 100) { + buf[5] |= 0x80; + buf[6] = bin2bcd(time->tm_year - 100); + } else { + buf[6] = bin2bcd(time->tm_year); + } + + return i2c_smbus_write_i2c_block_data(client, + DS3232_REG_SECONDS, 7, buf); +} + +static irqreturn_t ds3232_irq(int irq, void *dev_id) +{ + struct i2c_client *client = dev_id; + struct ds3232 *ds3232 = i2c_get_clientdata(client); + + disable_irq_nosync(irq); + schedule_work(&ds3232->work); + return IRQ_HANDLED; +} + +static void ds3232_work(struct work_struct *work) +{ + struct ds3232 *ds3232 = container_of(work, struct ds3232, work); + struct i2c_client *client = ds3232->client; + int stat, control; + + mutex_lock(&ds3232->mutex); + + stat = i2c_smbus_read_byte_data(client, DS3232_REG_SR); + if (stat < 0) + goto unlock; + + if (stat & DS3232_REG_SR_A1F) { + control = i2c_smbus_read_byte_data(client, DS3232_REG_CR); + if (control < 0) + goto out; + /* disable alarm1 interrupt */ + control &= ~(DS3232_REG_CR_A1IE); + i2c_smbus_write_byte_data(client, DS3232_REG_CR, control); + + /* clear the alarm pend flag */ + stat &= ~DS3232_REG_SR_A1F; + i2c_smbus_write_byte_data(client, DS3232_REG_SR, stat); + + rtc_update_irq(ds3232->rtc, 1, RTC_AF | RTC_IRQF); + } + +out: + if (!ds3232->exiting) + enable_irq(client->irq); +unlock: + mutex_unlock(&ds3232->mutex); +} + +static const struct rtc_class_ops ds3232_rtc_ops = { + .read_time = ds3232_read_time, + .set_time = ds3232_set_time, +}; + +static int __devinit ds3232_probe(struct i2c_client *client, + const struct i2c_device_id *id) +{ + struct ds3232 *ds3232; + int ret; + + ds3232 = kzalloc(sizeof(struct ds3232), GFP_KERNEL); + if (!ds3232) + return -ENOMEM; + + ds3232->client = client; + i2c_set_clientdata(client, ds3232); + + INIT_WORK(&ds3232->work, ds3232_work); + mutex_init(&ds3232->mutex); + + ret = ds3232_check_rtc_status(client); + if (ret) + goto out_free; + + ds3232->rtc = rtc_device_register(client->name, &client->dev, + &ds3232_rtc_ops, THIS_MODULE); + if (IS_ERR(ds3232->rtc)) { + ret = PTR_ERR(ds3232->rtc); + dev_err(&client->dev, "unable to register the class device\n"); + goto out_irq; + } + + if (client->irq >= 0) { + ret = request_irq(client->irq, ds3232_irq, 0, + "ds3232", client); + if (ret) { + dev_err(&client->dev, "unable to request IRQ\n"); + goto out_free; + } + } + + return 0; + +out_irq: + if (client->irq >= 0) + free_irq(client->irq, client); + +out_free: + i2c_set_clientdata(client, NULL); + kfree(ds3232); + return ret; +} + +static int __devexit ds3232_remove(struct i2c_client *client) +{ + struct ds3232 *ds3232 = i2c_get_clientdata(client); + + if (client->irq >= 0) { + mutex_lock(&ds3232->mutex); + ds3232->exiting = 1; + mutex_unlock(&ds3232->mutex); + + free_irq(client->irq, client); + flush_scheduled_work(); + } + + rtc_device_unregister(ds3232->rtc); + i2c_set_clientdata(client, NULL); + kfree(ds3232); + return 0; +} + +static const struct i2c_device_id ds3232_id[] = { + { "ds3232", 0 }, + { } +}; +MODULE_DEVICE_TABLE(i2c, ds3232_id); + +static struct i2c_driver ds3232_driver = { + .driver = { + .name = "rtc-ds3232", + .owner = THIS_MODULE, + }, + .probe = ds3232_probe, + .remove = __devexit_p(ds3232_remove), + .id_table = ds3232_id, +}; + +static int __init ds3232_init(void) +{ + return i2c_add_driver(&ds3232_driver); +} + +static void __exit ds3232_exit(void) +{ + i2c_del_driver(&ds3232_driver); +} + +module_init(ds3232_init); +module_exit(ds3232_exit); + +MODULE_AUTHOR("Srikanth Srinivasan <srikanth.srinivasan@freescale.com>"); +MODULE_DESCRIPTION("Maxim/Dallas DS3232 RTC Driver"); +MODULE_LICENSE("GPL"); |