/* * RTC client/driver for the Maxim/Dallas DS1374 Real-Time Clock over I2C * * Based on code by Randy Vinson <rvinson@mvista.com>, * which was based on the m41t00.c by Mark Greer <mgreer@mvista.com>. * * Copyright (C) 2006-2007 Freescale Semiconductor * * 2005 (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. */ /* * 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> #define DS1374_REG_TOD0 0x00 /* Time of Day */ #define DS1374_REG_TOD1 0x01 #define DS1374_REG_TOD2 0x02 #define DS1374_REG_TOD3 0x03 #define DS1374_REG_WDALM0 0x04 /* Watchdog/Alarm */ #define DS1374_REG_WDALM1 0x05 #define DS1374_REG_WDALM2 0x06 #define DS1374_REG_CR 0x07 /* Control */ #define DS1374_REG_CR_AIE 0x01 /* Alarm Int. Enable */ #define DS1374_REG_CR_WDALM 0x20 /* 1=Watchdog, 0=Alarm */ #define DS1374_REG_CR_WACE 0x40 /* WD/Alarm counter enable */ #define DS1374_REG_SR 0x08 /* Status */ #define DS1374_REG_SR_OSF 0x80 /* Oscillator Stop Flag */ #define DS1374_REG_SR_AF 0x01 /* Alarm Flag */ #define DS1374_REG_TCR 0x09 /* Trickle Charge */ struct ds1374 { 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 ds1374_driver; static int ds1374_read_rtc(struct i2c_client *client, u32 *time, int reg, int nbytes) { u8 buf[4]; int ret; int i; if (nbytes > 4) { WARN_ON(1); return -EINVAL; } ret = i2c_smbus_read_i2c_block_data(client, reg, nbytes, buf); if (ret < 0) return ret; if (ret < nbytes) return -EIO; for (i = nbytes - 1, *time = 0; i >= 0; i--) *time = (*time << 8) | buf[i]; return 0; } static int ds1374_write_rtc(struct i2c_client *client, u32 time, int reg, int nbytes) { u8 buf[4]; int i; if (nbytes > 4) { WARN_ON(1); return -EINVAL; } for (i = 0; i < nbytes; i++) { buf[i] = time & 0xff; time >>= 8; } return i2c_smbus_write_i2c_block_data(client, reg, nbytes, buf); } static int ds1374_check_rtc_status(struct i2c_client *client) { int ret = 0; int control, stat; stat = i2c_smbus_read_byte_data(client, DS1374_REG_SR); if (stat < 0) return stat; if (stat & DS1374_REG_SR_OSF) dev_warn(&client->dev, "oscillator discontinuity flagged, " "time unreliable\n"); stat &= ~(DS1374_REG_SR_OSF | DS1374_REG_SR_AF); ret = i2c_smbus_write_byte_data(client, DS1374_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, DS1374_REG_CR); if (control < 0) return control; control &= ~(DS1374_REG_CR_WACE | DS1374_REG_CR_AIE); return i2c_smbus_write_byte_data(client, DS1374_REG_CR, control); } static int ds1374_read_time(struct device *dev, struct rtc_time *time) { struct i2c_client *client = to_i2c_client(dev); u32 itime; int ret; ret = ds1374_read_rtc(client, &itime, DS1374_REG_TOD0, 4); if (!ret) rtc_time_to_tm(itime, time); return ret; } static int ds1374_set_time(struct device *dev, struct rtc_time *time) { struct i2c_client *client = to_i2c_client(dev); unsigned long itime; rtc_tm_to_time(time, &itime); return ds1374_write_rtc(client, itime, DS1374_REG_TOD0, 4); } /* The ds1374 has a decrementer for an alarm, rather than a comparator. * If the time of day is changed, then the alarm will need to be * reset. */ static int ds1374_read_alarm(struct device *dev, struct rtc_wkalrm *alarm) { struct i2c_client *client = to_i2c_client(dev); struct ds1374 *ds1374 = i2c_get_clientdata(client); u32 now, cur_alarm; int cr, sr; int ret = 0; if (client->irq < 0) return -EINVAL; mutex_lock(&ds1374->mutex); cr = ret = i2c_smbus_read_byte_data(client, DS1374_REG_CR); if (ret < 0) goto out; sr = ret = i2c_smbus_read_byte_data(client, DS1374_REG_SR); if (ret < 0) goto out; ret = ds1374_read_rtc(client, &now, DS1374_REG_TOD0, 4); if (ret) goto out; ret = ds1374_read_rtc(client, &cur_alarm, DS1374_REG_WDALM0, 3); if (ret) goto out; rtc_time_to_tm(now + cur_alarm, &alarm->time); alarm->enabled = !!(cr & DS1374_REG_CR_WACE); alarm->pending = !!(sr & DS1374_REG_SR_AF); out: mutex_unlock(&ds1374->mutex); return ret; } static int ds1374_set_alarm(struct device *dev, struct rtc_wkalrm *alarm) { struct i2c_client *client = to_i2c_client(dev); struct ds1374 *ds1374 = i2c_get_clientdata(client); struct rtc_time now; unsigned long new_alarm, itime; int cr; int ret = 0; if (client->irq < 0) return -EINVAL; ret = ds1374_read_time(dev, &now); if (ret < 0) return ret; rtc_tm_to_time(&alarm->time, &new_alarm); rtc_tm_to_time(&now, &itime); new_alarm -= itime; /* This can happen due to races, in addition to dates that are * truly in the past. To avoid requiring the caller to check for * races, dates in the past are assumed to be in the recent past * (i.e. not something that we'd rather the caller know about via * an error), and the alarm is set to go off as soon as possible. */ if (new_alarm <= 0) new_alarm = 1; mutex_lock(&ds1374->mutex); ret = cr = i2c_smbus_read_byte_data(client, DS1374_REG_CR); if (ret < 0) goto out; /* Disable any existing alarm before setting the new one * (or lack thereof). */ cr &= ~DS1374_REG_CR_WACE; ret = i2c_smbus_write_byte_data(client, DS1374_REG_CR, cr); if (ret < 0) goto out; ret = ds1374_write_rtc(client, new_alarm, DS1374_REG_WDALM0, 3); if (ret) goto out; if (alarm->enabled) { cr |= DS1374_REG_CR_WACE | DS1374_REG_CR_AIE; cr &= ~DS1374_REG_CR_WDALM; ret = i2c_smbus_write_byte_data(client, DS1374_REG_CR, cr); } out: mutex_unlock(&ds1374->mutex); return ret; } static irqreturn_t ds1374_irq(int irq, void *dev_id) { struct i2c_client *client = dev_id; struct ds1374 *ds1374 = i2c_get_clientdata(client); disable_irq_nosync(irq); schedule_work(&ds1374->work); return IRQ_HANDLED; } static void ds1374_work(struct work_struct *work) { struct ds1374 *ds1374 = container_of(work, struct ds1374, work); struct i2c_client *client = ds1374->client; int stat, control; mutex_lock(&ds1374->mutex); stat = i2c_smbus_read_byte_data(client, DS1374_REG_SR); if (stat < 0) return; if (stat & DS1374_REG_SR_AF) { stat &= ~DS1374_REG_SR_AF; i2c_smbus_write_byte_data(client, DS1374_REG_SR, stat); control = i2c_smbus_read_byte_data(client, DS1374_REG_CR); if (control < 0) goto out; control &= ~(DS1374_REG_CR_WACE | DS1374_REG_CR_AIE); i2c_smbus_write_byte_data(client, DS1374_REG_CR, control); /* rtc_update_irq() assumes that it is called * from IRQ-disabled context. */ local_irq_disable(); rtc_update_irq(ds1374->rtc, 1, RTC_AF | RTC_IRQF); local_irq_enable(); } out: if (!ds1374->exiting) enable_irq(client->irq); mutex_unlock(&ds1374->mutex); } static int ds1374_ioctl(struct device *dev, unsigned int cmd, unsigned long arg) { struct i2c_client *client = to_i2c_client(dev); struct ds1374 *ds1374 = i2c_get_clientdata(client); int ret = -ENOIOCTLCMD; mutex_lock(&ds1374->mutex); switch (cmd) { case RTC_AIE_OFF: ret = i2c_smbus_read_byte_data(client, DS1374_REG_CR); if (ret < 0) goto out; ret &= ~DS1374_REG_CR_WACE; ret = i2c_smbus_write_byte_data(client, DS1374_REG_CR, ret); if (ret < 0) goto out; break; case RTC_AIE_ON: ret = i2c_smbus_read_byte_data(client, DS1374_REG_CR); if (ret < 0) goto out; ret |= DS1374_REG_CR_WACE | DS1374_REG_CR_AIE; ret &= ~DS1374_REG_CR_WDALM; ret = i2c_smbus_write_byte_data(client, DS1374_REG_CR, ret); if (ret < 0) goto out; break; } out: mutex_unlock(&ds1374->mutex); return ret; } static const struct rtc_class_ops ds1374_rtc_ops = { .read_time = ds1374_read_time, .set_time = ds1374_set_time, .read_alarm = ds1374_read_alarm, .set_alarm = ds1374_set_alarm, .ioctl = ds1374_ioctl, }; static int ds1374_probe(struct i2c_client *client) { struct ds1374 *ds1374; int ret; ds1374 = kzalloc(sizeof(struct ds1374), GFP_KERNEL); if (!ds1374) return -ENOMEM; ds1374->client = client; i2c_set_clientdata(client, ds1374); INIT_WORK(&ds1374->work, ds1374_work); mutex_init(&ds1374->mutex); ret = ds1374_check_rtc_status(client); if (ret) goto out_free; if (client->irq >= 0) { ret = request_irq(client->irq, ds1374_irq, 0, "ds1374", client); if (ret) { dev_err(&client->dev, "unable to request IRQ\n"); goto out_free; } } ds1374->rtc = rtc_device_register(client->name, &client->dev, &ds1374_rtc_ops, THIS_MODULE); if (IS_ERR(ds1374->rtc)) { ret = PTR_ERR(ds1374->rtc); dev_err(&client->dev, "unable to register the class device\n"); goto out_irq; } return 0; out_irq: if (client->irq >= 0) free_irq(client->irq, client); out_free: i2c_set_clientdata(client, NULL); kfree(ds1374); return ret; } static int __devexit ds1374_remove(struct i2c_client *client) { struct ds1374 *ds1374 = i2c_get_clientdata(client); if (client->irq >= 0) { mutex_lock(&ds1374->mutex); ds1374->exiting = 1; mutex_unlock(&ds1374->mutex); free_irq(client->irq, client); flush_scheduled_work(); } rtc_device_unregister(ds1374->rtc); i2c_set_clientdata(client, NULL); kfree(ds1374); return 0; } static struct i2c_driver ds1374_driver = { .driver = { .name = "rtc-ds1374", .owner = THIS_MODULE, }, .probe = ds1374_probe, .remove = __devexit_p(ds1374_remove), }; static int __init ds1374_init(void) { return i2c_add_driver(&ds1374_driver); } static void __exit ds1374_exit(void) { i2c_del_driver(&ds1374_driver); } module_init(ds1374_init); module_exit(ds1374_exit); MODULE_AUTHOR("Scott Wood <scottwood@freescale.com>"); MODULE_DESCRIPTION("Maxim/Dallas DS1374 RTC Driver"); MODULE_LICENSE("GPL");