1 files changed, 326 insertions, 0 deletions
diff --git a/drivers/rtc/rtc-pcf8523.c b/drivers/rtc/rtc-pcf8523.c
new file mode 100644
index 000000000000..be05a645f99e
--- /dev/null
+++ b/drivers/rtc/rtc-pcf8523.c
@@ -0,0 +1,326 @@
+/*
+ * Copyright (C) 2012 Avionic Design GmbH
+ *
+ * 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/bcd.h>
+#include <linux/i2c.h>
+#include <linux/module.h>
+#include <linux/rtc.h>
+#include <linux/of.h>
+
+#define DRIVER_NAME "rtc-pcf8523"
+
+#define REG_CONTROL1 0x00
+#define REG_CONTROL1_CAP_SEL (1 << 7)
+#define REG_CONTROL1_STOP    (1 << 5)
+
+#define REG_CONTROL3 0x02
+#define REG_CONTROL3_PM_BLD (1 << 7) /* battery low detection disabled */
+#define REG_CONTROL3_PM_VDD (1 << 6) /* switch-over disabled */
+#define REG_CONTROL3_PM_DSM (1 << 5) /* direct switching mode */
+#define REG_CONTROL3_PM_MASK 0xe0
+
+#define REG_SECONDS  0x03
+#define REG_SECONDS_OS (1 << 7)
+
+#define REG_MINUTES  0x04
+#define REG_HOURS    0x05
+#define REG_DAYS     0x06
+#define REG_WEEKDAYS 0x07
+#define REG_MONTHS   0x08
+#define REG_YEARS    0x09
+
+struct pcf8523 {
+	struct rtc_device *rtc;
+};
+
+static int pcf8523_read(struct i2c_client *client, u8 reg, u8 *valuep)
+{
+	struct i2c_msg msgs[2];
+	u8 value = 0;
+	int err;
+
+	msgs[0].addr = client->addr;
+	msgs[0].flags = 0;
+	msgs[0].len = sizeof(reg);
+	msgs[0].buf = &reg;
+
+	msgs[1].addr = client->addr;
+	msgs[1].flags = I2C_M_RD;
+	msgs[1].len = sizeof(value);
+	msgs[1].buf = &value;
+
+	err = i2c_transfer(client->adapter, msgs, ARRAY_SIZE(msgs));
+	if (err < 0)
+		return err;
+
+	*valuep = value;
+
+	return 0;
+}
+
+static int pcf8523_write(struct i2c_client *client, u8 reg, u8 value)
+{
+	u8 buffer[2] = { reg, value };
+	struct i2c_msg msg;
+	int err;
+
+	msg.addr = client->addr;
+	msg.flags = 0;
+	msg.len = sizeof(buffer);
+	msg.buf = buffer;
+
+	err = i2c_transfer(client->adapter, &msg, 1);
+	if (err < 0)
+		return err;
+
+	return 0;
+}
+
+static int pcf8523_select_capacitance(struct i2c_client *client, bool high)
+{
+	u8 value;
+	int err;
+
+	err = pcf8523_read(client, REG_CONTROL1, &value);
+	if (err < 0)
+		return err;
+
+	if (!high)
+		value &= ~REG_CONTROL1_CAP_SEL;
+	else
+		value |= REG_CONTROL1_CAP_SEL;
+
+	err = pcf8523_write(client, REG_CONTROL1, value);
+	if (err < 0)
+		return err;
+
+	return err;
+}
+
+static int pcf8523_set_pm(struct i2c_client *client, u8 pm)
+{
+	u8 value;
+	int err;
+
+	err = pcf8523_read(client, REG_CONTROL3, &value);
+	if (err < 0)
+		return err;
+
+	value = (value & ~REG_CONTROL3_PM_MASK) | pm;
+
+	err = pcf8523_write(client, REG_CONTROL3, value);
+	if (err < 0)
+		return err;
+
+	return 0;
+}
+
+static int pcf8523_stop_rtc(struct i2c_client *client)
+{
+	u8 value;
+	int err;
+
+	err = pcf8523_read(client, REG_CONTROL1, &value);
+	if (err < 0)
+		return err;
+
+	value |= REG_CONTROL1_STOP;
+
+	err = pcf8523_write(client, REG_CONTROL1, value);
+	if (err < 0)
+		return err;
+
+	return 0;
+}
+
+static int pcf8523_start_rtc(struct i2c_client *client)
+{
+	u8 value;
+	int err;
+
+	err = pcf8523_read(client, REG_CONTROL1, &value);
+	if (err < 0)
+		return err;
+
+	value &= ~REG_CONTROL1_STOP;
+
+	err = pcf8523_write(client, REG_CONTROL1, value);
+	if (err < 0)
+		return err;
+
+	return 0;
+}
+
+static int pcf8523_rtc_read_time(struct device *dev, struct rtc_time *tm)
+{
+	struct i2c_client *client = to_i2c_client(dev);
+	u8 start = REG_SECONDS, regs[7];
+	struct i2c_msg msgs[2];
+	int err;
+
+	msgs[0].addr = client->addr;
+	msgs[0].flags = 0;
+	msgs[0].len = 1;
+	msgs[0].buf = &start;
+
+	msgs[1].addr = client->addr;
+	msgs[1].flags = I2C_M_RD;
+	msgs[1].len = sizeof(regs);
+	msgs[1].buf = regs;
+
+	err = i2c_transfer(client->adapter, msgs, ARRAY_SIZE(msgs));
+	if (err < 0)
+		return err;
+
+	if (regs[0] & REG_SECONDS_OS) {
+		/*
+		 * If the oscillator was stopped, try to clear the flag. Upon
+		 * power-up the flag is always set, but if we cannot clear it
+		 * the oscillator isn't running properly for some reason. The
+		 * sensible thing therefore is to return an error, signalling
+		 * that the clock cannot be assumed to be correct.
+		 */
+
+		regs[0] &= ~REG_SECONDS_OS;
+
+		err = pcf8523_write(client, REG_SECONDS, regs[0]);
+		if (err < 0)
+			return err;
+
+		err = pcf8523_read(client, REG_SECONDS, &regs[0]);
+		if (err < 0)
+			return err;
+
+		if (regs[0] & REG_SECONDS_OS)
+			return -EAGAIN;
+	}
+
+	tm->tm_sec = bcd2bin(regs[0] & 0x7f);
+	tm->tm_min = bcd2bin(regs[1] & 0x7f);
+	tm->tm_hour = bcd2bin(regs[2] & 0x3f);
+	tm->tm_mday = bcd2bin(regs[3] & 0x3f);
+	tm->tm_wday = regs[4] & 0x7;
+	tm->tm_mon = bcd2bin(regs[5] & 0x1f);
+	tm->tm_year = bcd2bin(regs[6]) + 100;
+
+	return rtc_valid_tm(tm);
+}
+
+static int pcf8523_rtc_set_time(struct device *dev, struct rtc_time *tm)
+{
+	struct i2c_client *client = to_i2c_client(dev);
+	struct i2c_msg msg;
+	u8 regs[8];
+	int err;
+
+	err = pcf8523_stop_rtc(client);
+	if (err < 0)
+		return err;
+
+	regs[0] = REG_SECONDS;
+	regs[1] = bin2bcd(tm->tm_sec);
+	regs[2] = bin2bcd(tm->tm_min);
+	regs[3] = bin2bcd(tm->tm_hour);
+	regs[4] = bin2bcd(tm->tm_mday);
+	regs[5] = tm->tm_wday;
+	regs[6] = bin2bcd(tm->tm_mon);
+	regs[7] = bin2bcd(tm->tm_year - 100);
+
+	msg.addr = client->addr;
+	msg.flags = 0;
+	msg.len = sizeof(regs);
+	msg.buf = regs;
+
+	err = i2c_transfer(client->adapter, &msg, 1);
+	if (err < 0) {
+		/*
+		 * If the time cannot be set, restart the RTC anyway. Note
+		 * that errors are ignored if the RTC cannot be started so
+		 * that we have a chance to propagate the original error.
+		 */
+		pcf8523_start_rtc(client);
+		return err;
+	}
+
+	return pcf8523_start_rtc(client);
+}
+
+static const struct rtc_class_ops pcf8523_rtc_ops = {
+	.read_time = pcf8523_rtc_read_time,
+	.set_time = pcf8523_rtc_set_time,
+};
+
+static int pcf8523_probe(struct i2c_client *client,
+			 const struct i2c_device_id *id)
+{
+	struct pcf8523 *pcf;
+	int err;
+
+	if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C))
+		return -ENODEV;
+
+	pcf = devm_kzalloc(&client->dev, sizeof(*pcf), GFP_KERNEL);
+	if (!pcf)
+		return -ENOMEM;
+
+	err = pcf8523_select_capacitance(client, true);
+	if (err < 0)
+		return err;
+
+	err = pcf8523_set_pm(client, 0);
+	if (err < 0)
+		return err;
+
+	pcf->rtc = rtc_device_register(DRIVER_NAME, &client->dev,
+				       &pcf8523_rtc_ops, THIS_MODULE);
+	if (IS_ERR(pcf->rtc))
+		return PTR_ERR(pcf->rtc);
+
+	i2c_set_clientdata(client, pcf);
+
+	return 0;
+}
+
+static int pcf8523_remove(struct i2c_client *client)
+{
+	struct pcf8523 *pcf = i2c_get_clientdata(client);
+
+	rtc_device_unregister(pcf->rtc);
+
+	return 0;
+}
+
+static const struct i2c_device_id pcf8523_id[] = {
+	{ "pcf8523", 0 },
+	{ }
+};
+MODULE_DEVICE_TABLE(i2c, pcf8523_id);
+
+#ifdef CONFIG_OF
+static const struct of_device_id pcf8523_of_match[] = {
+	{ .compatible = "nxp,pcf8523" },
+	{ }
+};
+MODULE_DEVICE_TABLE(of, pcf8523_of_match);
+#endif
+
+static struct i2c_driver pcf8523_driver = {
+	.driver = {
+		.name = DRIVER_NAME,
+		.owner = THIS_MODULE,
+		.of_match_table = of_match_ptr(pcf8523_of_match),
+	},
+	.probe = pcf8523_probe,
+	.remove = pcf8523_remove,
+	.id_table = pcf8523_id,
+};
+module_i2c_driver(pcf8523_driver);
+
+MODULE_AUTHOR("Thierry Reding <thierry.reding@avionic-design.de>");
+MODULE_DESCRIPTION("NXP PCF8523 RTC driver");
+MODULE_LICENSE("GPL v2");