--- /dev/null
+/*
+ * 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");
projects / GitHub / mt8127 / android_kernel_alcatel_ttab.git / commitdiff