rtc: add driver for BQ32000 I2C RTC
This patch adds basic support for Texas Instruments BQ32000 I2C RTC. Only
time reading/writing is implemented. Advanced features, such as trickle
charger and crystal calibration are not supported.
Signed-off-by: Piotr Ziecik <kosmo@semihalf.com>
Signed-off-by: Alessandro Zummo <a.zummo@towertech.it>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/drivers/rtc/rtc-bq32k.c b/drivers/rtc/rtc-bq32k.c
new file mode 100644
index 0000000..408cc8f
--- /dev/null
+++ b/drivers/rtc/rtc-bq32k.c
@@ -0,0 +1,204 @@
+/*
+ * Driver for TI BQ32000 RTC.
+ *
+ * Copyright (C) 2009 Semihalf.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ */
+
+#include <linux/module.h>
+#include <linux/i2c.h>
+#include <linux/rtc.h>
+#include <linux/init.h>
+#include <linux/errno.h>
+#include <linux/bcd.h>
+
+#define BQ32K_SECONDS 0x00 /* Seconds register address */
+#define BQ32K_SECONDS_MASK 0x7F /* Mask over seconds value */
+#define BQ32K_STOP 0x80 /* Oscillator Stop flat */
+
+#define BQ32K_MINUTES 0x01 /* Minutes register address */
+#define BQ32K_MINUTES_MASK 0x7F /* Mask over minutes value */
+#define BQ32K_OF 0x80 /* Oscillator Failure flag */
+
+#define BQ32K_HOURS_MASK 0x3F /* Mask over hours value */
+#define BQ32K_CENT 0x40 /* Century flag */
+#define BQ32K_CENT_EN 0x80 /* Century flag enable bit */
+
+struct bq32k_regs {
+ uint8_t seconds;
+ uint8_t minutes;
+ uint8_t cent_hours;
+ uint8_t day;
+ uint8_t date;
+ uint8_t month;
+ uint8_t years;
+};
+
+static struct i2c_driver bq32k_driver;
+
+static int bq32k_read(struct device *dev, void *data, uint8_t off, uint8_t len)
+{
+ struct i2c_client *client = to_i2c_client(dev);
+ struct i2c_msg msgs[] = {
+ {
+ .addr = client->addr,
+ .flags = 0,
+ .len = 1,
+ .buf = &off,
+ }, {
+ .addr = client->addr,
+ .flags = I2C_M_RD,
+ .len = len,
+ .buf = data,
+ }
+ };
+
+ if (i2c_transfer(client->adapter, msgs, 2) == 2)
+ return 0;
+
+ return -EIO;
+}
+
+static int bq32k_write(struct device *dev, void *data, uint8_t off, uint8_t len)
+{
+ struct i2c_client *client = to_i2c_client(dev);
+ uint8_t buffer[len + 1];
+
+ buffer[0] = off;
+ memcpy(&buffer[1], data, len);
+
+ if (i2c_master_send(client, buffer, len + 1) == len + 1)
+ return 0;
+
+ return -EIO;
+}
+
+static int bq32k_rtc_read_time(struct device *dev, struct rtc_time *tm)
+{
+ struct bq32k_regs regs;
+ int error;
+
+ error = bq32k_read(dev, ®s, 0, sizeof(regs));
+ if (error)
+ return error;
+
+ tm->tm_sec = bcd2bin(regs.seconds & BQ32K_SECONDS_MASK);
+ tm->tm_min = bcd2bin(regs.minutes & BQ32K_SECONDS_MASK);
+ tm->tm_hour = bcd2bin(regs.cent_hours & BQ32K_HOURS_MASK);
+ tm->tm_mday = bcd2bin(regs.date);
+ tm->tm_wday = bcd2bin(regs.day) - 1;
+ tm->tm_mon = bcd2bin(regs.month) - 1;
+ tm->tm_year = bcd2bin(regs.years) +
+ ((regs.cent_hours & BQ32K_CENT) ? 100 : 0);
+
+ return rtc_valid_tm(tm);
+}
+
+static int bq32k_rtc_set_time(struct device *dev, struct rtc_time *tm)
+{
+ struct bq32k_regs regs;
+
+ regs.seconds = bin2bcd(tm->tm_sec);
+ regs.minutes = bin2bcd(tm->tm_min);
+ regs.cent_hours = bin2bcd(tm->tm_hour) | BQ32K_CENT_EN;
+ regs.day = bin2bcd(tm->tm_wday + 1);
+ regs.date = bin2bcd(tm->tm_mday);
+ regs.month = bin2bcd(tm->tm_mon + 1);
+
+ if (tm->tm_year >= 100) {
+ regs.cent_hours |= BQ32K_CENT;
+ regs.years = bin2bcd(tm->tm_year - 100);
+ } else
+ regs.years = bin2bcd(tm->tm_year);
+
+ return bq32k_write(dev, ®s, 0, sizeof(regs));
+}
+
+static const struct rtc_class_ops bq32k_rtc_ops = {
+ .read_time = bq32k_rtc_read_time,
+ .set_time = bq32k_rtc_set_time,
+};
+
+static int bq32k_probe(struct i2c_client *client,
+ const struct i2c_device_id *id)
+{
+ struct device *dev = &client->dev;
+ struct rtc_device *rtc;
+ uint8_t reg;
+ int error;
+
+ if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C))
+ return -ENODEV;
+
+ /* Check Oscillator Stop flag */
+ error = bq32k_read(dev, ®, BQ32K_SECONDS, 1);
+ if (!error && (reg & BQ32K_STOP)) {
+ dev_warn(dev, "Oscillator was halted. Restarting...\n");
+ reg &= ~BQ32K_STOP;
+ error = bq32k_write(dev, ®, BQ32K_SECONDS, 1);
+ }
+ if (error)
+ return error;
+
+ /* Check Oscillator Failure flag */
+ error = bq32k_read(dev, ®, BQ32K_MINUTES, 1);
+ if (!error && (reg & BQ32K_OF)) {
+ dev_warn(dev, "Oscillator Failure. Check RTC battery.\n");
+ reg &= ~BQ32K_OF;
+ error = bq32k_write(dev, ®, BQ32K_MINUTES, 1);
+ }
+ if (error)
+ return error;
+
+ rtc = rtc_device_register(bq32k_driver.driver.name, &client->dev,
+ &bq32k_rtc_ops, THIS_MODULE);
+ if (IS_ERR(rtc))
+ return PTR_ERR(rtc);
+
+ i2c_set_clientdata(client, rtc);
+
+ return 0;
+}
+
+static int __devexit bq32k_remove(struct i2c_client *client)
+{
+ struct rtc_device *rtc = i2c_get_clientdata(client);
+
+ rtc_device_unregister(rtc);
+ return 0;
+}
+
+static const struct i2c_device_id bq32k_id[] = {
+ { "bq32000", 0 },
+ { }
+};
+MODULE_DEVICE_TABLE(i2c, bq32k_id);
+
+static struct i2c_driver bq32k_driver = {
+ .driver = {
+ .name = "bq32k",
+ .owner = THIS_MODULE,
+ },
+ .probe = bq32k_probe,
+ .remove = __devexit_p(bq32k_remove),
+ .id_table = bq32k_id,
+};
+
+static __init int bq32k_init(void)
+{
+ return i2c_add_driver(&bq32k_driver);
+}
+module_init(bq32k_init);
+
+static __exit void bq32k_exit(void)
+{
+ i2c_del_driver(&bq32k_driver);
+}
+module_exit(bq32k_exit);
+
+MODULE_AUTHOR("Semihalf, Piotr Ziecik <kosmo@semihalf.com>");
+MODULE_DESCRIPTION("TI BQ32000 I2C RTC driver");
+MODULE_LICENSE("GPL");