--- /dev/null
+/*
+ * 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");
projects / linux-2.6 / commitdiff