/* * RTC client/driver for the Maxim/Dallas DS3232 Real-Time Clock over I2C * * Copyright (C) 2009-2011 Freescale Semiconductor. * Author: Jack Lan <jack.lan@freescale.com> * * 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); } /* Day of the week in linux range is 0~6 while 1~7 in RTC chip */ time->tm_wday = bcd2bin(week) - 1; time->tm_mday = bcd2bin(day); /* linux tm_mon range:0~11, while month range is 1~12 in RTC chip */ time->tm_mon = bcd2bin(month & 0x7F) - 1; 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); /* Day of the week in linux range is 0~6 while 1~7 in RTC chip */ buf[3] = bin2bcd(time->tm_wday + 1); buf[4] = bin2bcd(time->tm_mday); /* Date */ /* linux tm_mon range:0~11, while month range is 1~12 in RTC chip */ buf[5] = bin2bcd(time->tm_mon + 1); 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); } /* * DS3232 has two alarm, we only use alarm1 * According to linux specification, only support one-shot alarm * no periodic alarm mode */ static int ds3232_read_alarm(struct device *dev, struct rtc_wkalrm *alarm) { struct i2c_client *client = to_i2c_client(dev); struct ds3232 *ds3232 = i2c_get_clientdata(client); int control, stat; int ret; u8 buf[4]; mutex_lock(&ds3232->mutex); ret = i2c_smbus_read_byte_data(client, DS3232_REG_SR); if (ret < 0) goto out; stat = ret; ret = i2c_smbus_read_byte_data(client, DS3232_REG_CR); if (ret < 0) goto out; control = ret; ret = i2c_smbus_read_i2c_block_data(client, DS3232_REG_ALARM1, 4, buf); if (ret < 0) goto out; alarm->time.tm_sec = bcd2bin(buf[0] & 0x7F); alarm->time.tm_min = bcd2bin(buf[1] & 0x7F); alarm->time.tm_hour = bcd2bin(buf[2] & 0x7F); alarm->time.tm_mday = bcd2bin(buf[3] & 0x7F); alarm->time.tm_mon = -1; alarm->time.tm_year = -1; alarm->time.tm_wday = -1; alarm->time.tm_yday = -1; alarm->time.tm_isdst = -1; alarm->enabled = !!(control & DS3232_REG_CR_A1IE); alarm->pending = !!(stat & DS3232_REG_SR_A1F); ret = 0; out: mutex_unlock(&ds3232->mutex); return ret; } /* * linux rtc-module does not support wday alarm * and only 24h time mode supported indeed */ static int ds3232_set_alarm(struct device *dev, struct rtc_wkalrm *alarm) { struct i2c_client *client = to_i2c_client(dev); struct ds3232 *ds3232 = i2c_get_clientdata(client); int control, stat; int ret; u8 buf[4]; if (client->irq <= 0) return -EINVAL; mutex_lock(&ds3232->mutex); buf[0] = bin2bcd(alarm->time.tm_sec); buf[1] = bin2bcd(alarm->time.tm_min); buf[2] = bin2bcd(alarm->time.tm_hour); buf[3] = bin2bcd(alarm->time.tm_mday); /* clear alarm interrupt enable bit */ ret = i2c_smbus_read_byte_data(client, DS3232_REG_CR); if (ret < 0) goto out; control = ret; control &= ~(DS3232_REG_CR_A1IE | DS3232_REG_CR_A2IE); ret = i2c_smbus_write_byte_data(client, DS3232_REG_CR, control); if (ret < 0) goto out; /* clear any pending alarm flag */ ret = i2c_smbus_read_byte_data(client, DS3232_REG_SR); if (ret < 0) goto out; stat = ret; stat &= ~(DS3232_REG_SR_A1F | DS3232_REG_SR_A2F); ret = i2c_smbus_write_byte_data(client, DS3232_REG_SR, stat); if (ret < 0) goto out; ret = i2c_smbus_write_i2c_block_data(client, DS3232_REG_ALARM1, 4, buf); if (alarm->enabled) { control |= DS3232_REG_CR_A1IE; ret = i2c_smbus_write_byte_data(client, DS3232_REG_CR, control); } out: mutex_unlock(&ds3232->mutex); return ret; } static void ds3232_update_alarm(struct i2c_client *client) { struct ds3232 *ds3232 = i2c_get_clientdata(client); int control; int ret; u8 buf[4]; mutex_lock(&ds3232->mutex); ret = i2c_smbus_read_i2c_block_data(client, DS3232_REG_ALARM1, 4, buf); if (ret < 0) goto unlock; buf[0] = bcd2bin(buf[0]) < 0 || (ds3232->rtc->irq_data & RTC_UF) ? 0x80 : buf[0]; buf[1] = bcd2bin(buf[1]) < 0 || (ds3232->rtc->irq_data & RTC_UF) ? 0x80 : buf[1]; buf[2] = bcd2bin(buf[2]) < 0 || (ds3232->rtc->irq_data & RTC_UF) ? 0x80 : buf[2]; buf[3] = bcd2bin(buf[3]) < 0 || (ds3232->rtc->irq_data & RTC_UF) ? 0x80 : buf[3]; ret = i2c_smbus_write_i2c_block_data(client, DS3232_REG_ALARM1, 4, buf); if (ret < 0) goto unlock; control = i2c_smbus_read_byte_data(client, DS3232_REG_CR); if (control < 0) goto unlock; if (ds3232->rtc->irq_data & (RTC_AF | RTC_UF)) /* enable alarm1 interrupt */ control |= DS3232_REG_CR_A1IE; else /* disable alarm1 interrupt */ control &= ~(DS3232_REG_CR_A1IE); i2c_smbus_write_byte_data(client, DS3232_REG_CR, control); unlock: mutex_unlock(&ds3232->mutex); } static int ds3232_alarm_irq_enable(struct device *dev, unsigned int enabled) { struct i2c_client *client = to_i2c_client(dev); struct ds3232 *ds3232 = i2c_get_clientdata(client); if (client->irq <= 0) return -EINVAL; if (enabled) ds3232->rtc->irq_data |= RTC_AF; else ds3232->rtc->irq_data &= ~RTC_AF; ds3232_update_alarm(client); return 0; } 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, .read_alarm = ds3232_read_alarm, .set_alarm = ds3232_set_alarm, .alarm_irq_enable = ds3232_alarm_irq_enable, }; static int ds3232_probe(struct i2c_client *client, const struct i2c_device_id *id) { struct ds3232 *ds3232; int ret; ds3232 = devm_kzalloc(&client->dev, 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) return ret; ds3232->rtc = devm_rtc_device_register(&client->dev, client->name, &ds3232_rtc_ops, THIS_MODULE); if (IS_ERR(ds3232->rtc)) { dev_err(&client->dev, "unable to register the class device\n"); return PTR_ERR(ds3232->rtc); } if (client->irq >= 0) { ret = devm_request_irq(&client->dev, client->irq, ds3232_irq, 0, "ds3232", client); if (ret) { dev_err(&client->dev, "unable to request IRQ\n"); return ret; } } return 0; } static int 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); devm_free_irq(&client->dev, client->irq, client); cancel_work_sync(&ds3232->work); } 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 = ds3232_remove, .id_table = ds3232_id, }; module_i2c_driver(ds3232_driver); MODULE_AUTHOR("Srikanth Srinivasan <srikanth.srinivasan@freescale.com>"); MODULE_DESCRIPTION("Maxim/Dallas DS3232 RTC Driver"); MODULE_LICENSE("GPL");