drivers/rtc/rtc-pcf8563.c - linux - Git at Google

 // SPDX-License-Identifier: GPL-2.0-only
 /*
  * An I2C driver for the Philips PCF8563 RTC
  * Copyright 2005-06 Tower Technologies
  *
  * Author: Alessandro Zummo <a.zummo@towertech.it>
  * Maintainers: http://www.nslu2-linux.org/
  *
  * based on the other drivers in this same directory.
  *
  * http://www.semiconductors.philips.com/acrobat/datasheets/PCF8563-04.pdf
  */

 #include <linux/clk-provider.h>
 #include <linux/i2c.h>
 #include <linux/bcd.h>
 #include <linux/rtc.h>
 #include <linux/slab.h>
 #include <linux/module.h>
 #include <linux/of.h>
 #include <linux/err.h>

 #define PCF8563_REG_ST1		0x00 /* status */
 #define PCF8563_REG_ST2		0x01
 #define PCF8563_BIT_AIE		(1 << 1)
 #define PCF8563_BIT_AF		(1 << 3)
 #define PCF8563_BITS_ST2_N	(7 << 5)

 #define PCF8563_REG_SC		0x02 /* datetime */
 #define PCF8563_REG_MN		0x03
 #define PCF8563_REG_HR		0x04
 #define PCF8563_REG_DM		0x05
 #define PCF8563_REG_DW		0x06
 #define PCF8563_REG_MO		0x07
 #define PCF8563_REG_YR		0x08

 #define PCF8563_REG_AMN		0x09 /* alarm */

 #define PCF8563_REG_CLKO		0x0D /* clock out */
 #define PCF8563_REG_CLKO_FE		0x80 /* clock out enabled */
 #define PCF8563_REG_CLKO_F_MASK		0x03 /* frequenc mask */
 #define PCF8563_REG_CLKO_F_32768HZ	0x00
 #define PCF8563_REG_CLKO_F_1024HZ	0x01
 #define PCF8563_REG_CLKO_F_32HZ		0x02
 #define PCF8563_REG_CLKO_F_1HZ		0x03

 #define PCF8563_REG_TMRC	0x0E /* timer control */
 #define PCF8563_TMRC_ENABLE	BIT(7)
 #define PCF8563_TMRC_4096	0
 #define PCF8563_TMRC_64		1
 #define PCF8563_TMRC_1		2
 #define PCF8563_TMRC_1_60	3
 #define PCF8563_TMRC_MASK	3

 #define PCF8563_REG_TMR		0x0F /* timer */

 #define PCF8563_SC_LV		0x80 /* low voltage */
 #define PCF8563_MO_C		0x80 /* century */

 static struct i2c_driver pcf8563_driver;

 struct pcf8563 {
 	struct rtc_device *rtc;
 	/*
 	 * The meaning of MO_C bit varies by the chip type.
 	 * From PCF8563 datasheet: this bit is toggled when the years
 	 * register overflows from 99 to 00
 	 *   0 indicates the century is 20xx
 	 *   1 indicates the century is 19xx
 	 * From RTC8564 datasheet: this bit indicates change of
 	 * century. When the year digit data overflows from 99 to 00,
 	 * this bit is set. By presetting it to 0 while still in the
 	 * 20th century, it will be set in year 2000, ...
 	 * There seems no reliable way to know how the system use this
 	 * bit.  So let's do it heuristically, assuming we are live in
 	 * 1970...2069.
 	 */
 	int c_polarity;	/* 0: MO_C=1 means 19xx, otherwise MO_C=1 means 20xx */
 	int voltage_low; /* incicates if a low_voltage was detected */

 	struct i2c_client *client;
 #ifdef CONFIG_COMMON_CLK
 	struct clk_hw		clkout_hw;
 #endif
 };

 static int pcf8563_read_block_data(struct i2c_client *client, unsigned char reg,
 				   unsigned char length, unsigned char *buf)
 {
 	struct i2c_msg msgs[] = {
 		{/* setup read ptr */
 			.addr = client->addr,
 			.len = 1,
 			.buf = &reg,
 		},
 		{
 			.addr = client->addr,
 			.flags = I2C_M_RD,
 			.len = length,
 			.buf = buf
 		},
 	};

 	if ((i2c_transfer(client->adapter, msgs, 2)) != 2) {
 		dev_err(&client->dev, "%s: read error\n", __func__);
 		return -EIO;
 	}

 	return 0;
 }

 static int pcf8563_write_block_data(struct i2c_client *client,
 				   unsigned char reg, unsigned char length,
 				   unsigned char *buf)
 {
 	int i, err;

 	for (i = 0; i < length; i++) {
 		unsigned char data[2] = { reg + i, buf[i] };

 		err = i2c_master_send(client, data, sizeof(data));
 		if (err != sizeof(data)) {
 			dev_err(&client->dev,
 				"%s: err=%d addr=%02x, data=%02x\n",
 				__func__, err, data[0], data[1]);
 			return -EIO;
 		}
 	}

 	return 0;
 }

 static int pcf8563_set_alarm_mode(struct i2c_client *client, bool on)
 {
 	unsigned char buf;
 	int err;

 	err = pcf8563_read_block_data(client, PCF8563_REG_ST2, 1, &buf);
 	if (err < 0)
 		return err;

 	if (on)
 		buf |= PCF8563_BIT_AIE;
 	else
 		buf &= ~PCF8563_BIT_AIE;

 	buf &= ~(PCF8563_BIT_AF | PCF8563_BITS_ST2_N);

 	err = pcf8563_write_block_data(client, PCF8563_REG_ST2, 1, &buf);
 	if (err < 0) {
 		dev_err(&client->dev, "%s: write error\n", __func__);
 		return -EIO;
 	}

 	return 0;
 }

 static int pcf8563_get_alarm_mode(struct i2c_client *client, unsigned char *en,
 				  unsigned char *pen)
 {
 	unsigned char buf;
 	int err;

 	err = pcf8563_read_block_data(client, PCF8563_REG_ST2, 1, &buf);
 	if (err)
 		return err;

 	if (en)
 		*en = !!(buf & PCF8563_BIT_AIE);
 	if (pen)
 		*pen = !!(buf & PCF8563_BIT_AF);

 	return 0;
 }

 static irqreturn_t pcf8563_irq(int irq, void *dev_id)
 {
 	struct pcf8563 *pcf8563 = i2c_get_clientdata(dev_id);
 	int err;
 	char pending;

 	err = pcf8563_get_alarm_mode(pcf8563->client, NULL, &pending);
 	if (err)
 		return IRQ_NONE;

 	if (pending) {
 		rtc_update_irq(pcf8563->rtc, 1, RTC_IRQF | RTC_AF);
 		pcf8563_set_alarm_mode(pcf8563->client, 1);
 		return IRQ_HANDLED;
 	}

 	return IRQ_NONE;
 }

 /*
  * In the routines that deal directly with the pcf8563 hardware, we use
  * rtc_time -- month 0-11, hour 0-23, yr = calendar year-epoch.
  */
 static int pcf8563_rtc_read_time(struct device *dev, struct rtc_time *tm)
 {
 	struct i2c_client *client = to_i2c_client(dev);
 	struct pcf8563 *pcf8563 = i2c_get_clientdata(client);
 	unsigned char buf[9];
 	int err;

 	err = pcf8563_read_block_data(client, PCF8563_REG_ST1, 9, buf);
 	if (err)
 		return err;

 	if (buf[PCF8563_REG_SC] & PCF8563_SC_LV) {
 		pcf8563->voltage_low = 1;
 		dev_err(&client->dev,
 			"low voltage detected, date/time is not reliable.\n");
 		return -EINVAL;
 	}

 	dev_dbg(&client->dev,
 		"%s: raw data is st1=%02x, st2=%02x, sec=%02x, min=%02x, hr=%02x, "
 		"mday=%02x, wday=%02x, mon=%02x, year=%02x\n",
 		__func__,
 		buf[0], buf[1], buf[2], buf[3],
 		buf[4], buf[5], buf[6], buf[7],
 		buf[8]);


 	tm->tm_sec = bcd2bin(buf[PCF8563_REG_SC] & 0x7F);
 	tm->tm_min = bcd2bin(buf[PCF8563_REG_MN] & 0x7F);
 	tm->tm_hour = bcd2bin(buf[PCF8563_REG_HR] & 0x3F); /* rtc hr 0-23 */
 	tm->tm_mday = bcd2bin(buf[PCF8563_REG_DM] & 0x3F);
 	tm->tm_wday = buf[PCF8563_REG_DW] & 0x07;
 	tm->tm_mon = bcd2bin(buf[PCF8563_REG_MO] & 0x1F) - 1; /* rtc mn 1-12 */
 	tm->tm_year = bcd2bin(buf[PCF8563_REG_YR]) + 100;
 	/* detect the polarity heuristically. see note above. */
 	pcf8563->c_polarity = (buf[PCF8563_REG_MO] & PCF8563_MO_C) ?
 		(tm->tm_year >= 100) : (tm->tm_year < 100);

 	dev_dbg(&client->dev, "%s: tm is secs=%d, mins=%d, hours=%d, "
 		"mday=%d, mon=%d, year=%d, wday=%d\n",
 		__func__,
 		tm->tm_sec, tm->tm_min, tm->tm_hour,
 		tm->tm_mday, tm->tm_mon, tm->tm_year, tm->tm_wday);

 	return 0;
 }

 static int pcf8563_rtc_set_time(struct device *dev, struct rtc_time *tm)
 {
 	struct i2c_client *client = to_i2c_client(dev);
 	struct pcf8563 *pcf8563 = i2c_get_clientdata(client);
 	unsigned char buf[9];

 	dev_dbg(&client->dev, "%s: secs=%d, mins=%d, hours=%d, "
 		"mday=%d, mon=%d, year=%d, wday=%d\n",
 		__func__,
 		tm->tm_sec, tm->tm_min, tm->tm_hour,
 		tm->tm_mday, tm->tm_mon, tm->tm_year, tm->tm_wday);

 	/* hours, minutes and seconds */
 	buf[PCF8563_REG_SC] = bin2bcd(tm->tm_sec);
 	buf[PCF8563_REG_MN] = bin2bcd(tm->tm_min);
 	buf[PCF8563_REG_HR] = bin2bcd(tm->tm_hour);

 	buf[PCF8563_REG_DM] = bin2bcd(tm->tm_mday);

 	/* month, 1 - 12 */
 	buf[PCF8563_REG_MO] = bin2bcd(tm->tm_mon + 1);

 	/* year and century */
 	buf[PCF8563_REG_YR] = bin2bcd(tm->tm_year - 100);
 	if (pcf8563->c_polarity ? (tm->tm_year >= 100) : (tm->tm_year < 100))
 		buf[PCF8563_REG_MO] |= PCF8563_MO_C;

 	buf[PCF8563_REG_DW] = tm->tm_wday & 0x07;

 	return pcf8563_write_block_data(client, PCF8563_REG_SC,
 				9 - PCF8563_REG_SC, buf + PCF8563_REG_SC);
 }

 #ifdef CONFIG_RTC_INTF_DEV
 static int pcf8563_rtc_ioctl(struct device *dev, unsigned int cmd, unsigned long arg)
 {
 	struct pcf8563 *pcf8563 = i2c_get_clientdata(to_i2c_client(dev));
 	struct rtc_time tm;

 	switch (cmd) {
 	case RTC_VL_READ:
 		if (pcf8563->voltage_low)
 			dev_info(dev, "low voltage detected, date/time is not reliable.\n");

 		if (copy_to_user((void __user *)arg, &pcf8563->voltage_low,
 					sizeof(int)))
 			return -EFAULT;
 		return 0;
 	case RTC_VL_CLR:
 		/*
 		 * Clear the VL bit in the seconds register in case
 		 * the time has not been set already (which would
 		 * have cleared it). This does not really matter
 		 * because of the cached voltage_low value but do it
 		 * anyway for consistency.
 		 */
 		if (pcf8563_rtc_read_time(dev, &tm))
 			pcf8563_rtc_set_time(dev, &tm);

 		/* Clear the cached value. */
 		pcf8563->voltage_low = 0;

 		return 0;
 	default:
 		return -ENOIOCTLCMD;
 	}
 }
 #else
 #define pcf8563_rtc_ioctl NULL
 #endif

 static int pcf8563_rtc_read_alarm(struct device *dev, struct rtc_wkalrm *tm)
 {
 	struct i2c_client *client = to_i2c_client(dev);
 	unsigned char buf[4];
 	int err;

 	err = pcf8563_read_block_data(client, PCF8563_REG_AMN, 4, buf);
 	if (err)
 		return err;

 	dev_dbg(&client->dev,
 		"%s: raw data is min=%02x, hr=%02x, mday=%02x, wday=%02x\n",
 		__func__, buf[0], buf[1], buf[2], buf[3]);

 	tm->time.tm_sec = 0;
 	tm->time.tm_min = bcd2bin(buf[0] & 0x7F);
 	tm->time.tm_hour = bcd2bin(buf[1] & 0x3F);
 	tm->time.tm_mday = bcd2bin(buf[2] & 0x3F);
 	tm->time.tm_wday = bcd2bin(buf[3] & 0x7);

 	err = pcf8563_get_alarm_mode(client, &tm->enabled, &tm->pending);
 	if (err < 0)
 		return err;

 	dev_dbg(&client->dev, "%s: tm is mins=%d, hours=%d, mday=%d, wday=%d,"
 		" enabled=%d, pending=%d\n", __func__, tm->time.tm_min,
 		tm->time.tm_hour, tm->time.tm_mday, tm->time.tm_wday,
 		tm->enabled, tm->pending);

 	return 0;
 }

 static int pcf8563_rtc_set_alarm(struct device *dev, struct rtc_wkalrm *tm)
 {
 	struct i2c_client *client = to_i2c_client(dev);
 	unsigned char buf[4];
 	int err;

 	/* The alarm has no seconds, round up to nearest minute */
 	if (tm->time.tm_sec) {
 		time64_t alarm_time = rtc_tm_to_time64(&tm->time);

 		alarm_time += 60 - tm->time.tm_sec;
 		rtc_time64_to_tm(alarm_time, &tm->time);
 	}

 	dev_dbg(dev, "%s, min=%d hour=%d wday=%d mday=%d "
 		"enabled=%d pending=%d\n", __func__,
 		tm->time.tm_min, tm->time.tm_hour, tm->time.tm_wday,
 		tm->time.tm_mday, tm->enabled, tm->pending);

 	buf[0] = bin2bcd(tm->time.tm_min);
 	buf[1] = bin2bcd(tm->time.tm_hour);
 	buf[2] = bin2bcd(tm->time.tm_mday);
 	buf[3] = tm->time.tm_wday & 0x07;

 	err = pcf8563_write_block_data(client, PCF8563_REG_AMN, 4, buf);
 	if (err)
 		return err;

 	return pcf8563_set_alarm_mode(client, !!tm->enabled);
 }

 static int pcf8563_irq_enable(struct device *dev, unsigned int enabled)
 {
 	dev_dbg(dev, "%s: en=%d\n", __func__, enabled);
 	return pcf8563_set_alarm_mode(to_i2c_client(dev), !!enabled);
 }

 #ifdef CONFIG_COMMON_CLK
 /*
  * Handling of the clkout
  */

 #define clkout_hw_to_pcf8563(_hw) container_of(_hw, struct pcf8563, clkout_hw)

 static const int clkout_rates[] = {
 	32768,
 	1024,
 	32,
 	1,
 };

 static unsigned long pcf8563_clkout_recalc_rate(struct clk_hw *hw,
 						unsigned long parent_rate)
 {
 	struct pcf8563 *pcf8563 = clkout_hw_to_pcf8563(hw);
 	struct i2c_client *client = pcf8563->client;
 	unsigned char buf;
 	int ret = pcf8563_read_block_data(client, PCF8563_REG_CLKO, 1, &buf);

 	if (ret < 0)
 		return 0;

 	buf &= PCF8563_REG_CLKO_F_MASK;
 	return clkout_rates[buf];
 }

 static long pcf8563_clkout_round_rate(struct clk_hw *hw, unsigned long rate,
 				      unsigned long *prate)
 {
 	int i;

 	for (i = 0; i < ARRAY_SIZE(clkout_rates); i++)
 		if (clkout_rates[i] <= rate)
 			return clkout_rates[i];

 	return 0;
 }

 static int pcf8563_clkout_set_rate(struct clk_hw *hw, unsigned long rate,
 				   unsigned long parent_rate)
 {
 	struct pcf8563 *pcf8563 = clkout_hw_to_pcf8563(hw);
 	struct i2c_client *client = pcf8563->client;
 	unsigned char buf;
 	int ret = pcf8563_read_block_data(client, PCF8563_REG_CLKO, 1, &buf);
 	int i;

 	if (ret < 0)
 		return ret;

 	for (i = 0; i < ARRAY_SIZE(clkout_rates); i++)
 		if (clkout_rates[i] == rate) {
 			buf &= ~PCF8563_REG_CLKO_F_MASK;
 			buf |= i;
 			ret = pcf8563_write_block_data(client,
 						       PCF8563_REG_CLKO, 1,
 						       &buf);
 			return ret;
 		}

 	return -EINVAL;
 }

 static int pcf8563_clkout_control(struct clk_hw *hw, bool enable)
 {
 	struct pcf8563 *pcf8563 = clkout_hw_to_pcf8563(hw);
 	struct i2c_client *client = pcf8563->client;
 	unsigned char buf;
 	int ret = pcf8563_read_block_data(client, PCF8563_REG_CLKO, 1, &buf);

 	if (ret < 0)
 		return ret;

 	if (enable)
 		buf |= PCF8563_REG_CLKO_FE;
 	else
 		buf &= ~PCF8563_REG_CLKO_FE;

 	ret = pcf8563_write_block_data(client, PCF8563_REG_CLKO, 1, &buf);
 	return ret;
 }

 static int pcf8563_clkout_prepare(struct clk_hw *hw)
 {
 	return pcf8563_clkout_control(hw, 1);
 }

 static void pcf8563_clkout_unprepare(struct clk_hw *hw)
 {
 	pcf8563_clkout_control(hw, 0);
 }

 static int pcf8563_clkout_is_prepared(struct clk_hw *hw)
 {
 	struct pcf8563 *pcf8563 = clkout_hw_to_pcf8563(hw);
 	struct i2c_client *client = pcf8563->client;
 	unsigned char buf;
 	int ret = pcf8563_read_block_data(client, PCF8563_REG_CLKO, 1, &buf);

 	if (ret < 0)
 		return ret;

 	return !!(buf & PCF8563_REG_CLKO_FE);
 }

 static const struct clk_ops pcf8563_clkout_ops = {
 	.prepare = pcf8563_clkout_prepare,
 	.unprepare = pcf8563_clkout_unprepare,
 	.is_prepared = pcf8563_clkout_is_prepared,
 	.recalc_rate = pcf8563_clkout_recalc_rate,
 	.round_rate = pcf8563_clkout_round_rate,
 	.set_rate = pcf8563_clkout_set_rate,
 };

 static struct clk *pcf8563_clkout_register_clk(struct pcf8563 *pcf8563)
 {
 	struct i2c_client *client = pcf8563->client;
 	struct device_node *node = client->dev.of_node;
 	struct clk *clk;
 	struct clk_init_data init;
 	int ret;
 	unsigned char buf;

 	/* disable the clkout output */
 	buf = 0;
 	ret = pcf8563_write_block_data(client, PCF8563_REG_CLKO, 1, &buf);
 	if (ret < 0)
 		return ERR_PTR(ret);

 	init.name = "pcf8563-clkout";
 	init.ops = &pcf8563_clkout_ops;
 	init.flags = 0;
 	init.parent_names = NULL;
 	init.num_parents = 0;
 	pcf8563->clkout_hw.init = &init;

 	/* optional override of the clockname */
 	of_property_read_string(node, "clock-output-names", &init.name);

 	/* register the clock */
 	clk = devm_clk_register(&client->dev, &pcf8563->clkout_hw);

 	if (!IS_ERR(clk))
 		of_clk_add_provider(node, of_clk_src_simple_get, clk);

 	return clk;
 }
 #endif

 static const struct rtc_class_ops pcf8563_rtc_ops = {
 	.ioctl		= pcf8563_rtc_ioctl,
 	.read_time	= pcf8563_rtc_read_time,
 	.set_time	= pcf8563_rtc_set_time,
 	.read_alarm	= pcf8563_rtc_read_alarm,
 	.set_alarm	= pcf8563_rtc_set_alarm,
 	.alarm_irq_enable = pcf8563_irq_enable,
 };

 static int pcf8563_probe(struct i2c_client *client,
 				const struct i2c_device_id *id)
 {
 	struct pcf8563 *pcf8563;
 	int err;
 	unsigned char buf;

 	dev_dbg(&client->dev, "%s\n", __func__);

 	if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C))
 		return -ENODEV;

 	pcf8563 = devm_kzalloc(&client->dev, sizeof(struct pcf8563),
 				GFP_KERNEL);
 	if (!pcf8563)
 		return -ENOMEM;

 	i2c_set_clientdata(client, pcf8563);
 	pcf8563->client = client;
 	device_set_wakeup_capable(&client->dev, 1);

 	/* Set timer to lowest frequency to save power (ref Haoyu datasheet) */
 	buf = PCF8563_TMRC_1_60;
 	err = pcf8563_write_block_data(client, PCF8563_REG_TMRC, 1, &buf);
 	if (err < 0) {
 		dev_err(&client->dev, "%s: write error\n", __func__);
 		return err;
 	}

 	/* Clear flags and disable interrupts */
 	buf = 0;
 	err = pcf8563_write_block_data(client, PCF8563_REG_ST2, 1, &buf);
 	if (err < 0) {
 		dev_err(&client->dev, "%s: write error\n", __func__);
 		return err;
 	}

 	pcf8563->rtc = devm_rtc_allocate_device(&client->dev);
 	if (IS_ERR(pcf8563->rtc))
 		return PTR_ERR(pcf8563->rtc);

 	pcf8563->rtc->ops = &pcf8563_rtc_ops;
 	/* the pcf8563 alarm only supports a minute accuracy */
 	pcf8563->rtc->uie_unsupported = 1;
 	pcf8563->rtc->range_min = RTC_TIMESTAMP_BEGIN_2000;
 	pcf8563->rtc->range_max = RTC_TIMESTAMP_END_2099;
 	pcf8563->rtc->set_start_time = true;

 	if (client->irq > 0) {
 		err = devm_request_threaded_irq(&client->dev, client->irq,
 				NULL, pcf8563_irq,
 				IRQF_SHARED | IRQF_ONESHOT | IRQF_TRIGGER_LOW,
 				pcf8563_driver.driver.name, client);
 		if (err) {
 			dev_err(&client->dev, "unable to request IRQ %d\n",
 								client->irq);
 			return err;
 		}
 	}

 	err = rtc_register_device(pcf8563->rtc);
 	if (err)
 		return err;

 #ifdef CONFIG_COMMON_CLK
 	/* register clk in common clk framework */
 	pcf8563_clkout_register_clk(pcf8563);
 #endif

 	return 0;
 }

 static const struct i2c_device_id pcf8563_id[] = {
 	{ "pcf8563", 0 },
 	{ "rtc8564", 0 },
 	{ }
 };
 MODULE_DEVICE_TABLE(i2c, pcf8563_id);

 #ifdef CONFIG_OF
 static const struct of_device_id pcf8563_of_match[] = {
 	{ .compatible = "nxp,pcf8563" },
 	{ .compatible = "epson,rtc8564" },
 	{ .compatible = "microcrystal,rv8564" },
 	{}
 };
 MODULE_DEVICE_TABLE(of, pcf8563_of_match);
 #endif

 static struct i2c_driver pcf8563_driver = {
 	.driver		= {
 		.name	= "rtc-pcf8563",
 		.of_match_table = of_match_ptr(pcf8563_of_match),
 	},
 	.probe		= pcf8563_probe,
 	.id_table	= pcf8563_id,
 };

 module_i2c_driver(pcf8563_driver);

 MODULE_AUTHOR("Alessandro Zummo <a.zummo@towertech.it>");
 MODULE_DESCRIPTION("Philips PCF8563/Epson RTC8564 RTC driver");
 MODULE_LICENSE("GPL");
	// SPDX-License-Identifier: GPL-2.0-only
	/*
	* An I2C driver for the Philips PCF8563 RTC
	* Copyright 2005-06 Tower Technologies
	*
	* Author: Alessandro Zummo <a.zummo@towertech.it>
	* Maintainers: http://www.nslu2-linux.org/
	*
	* based on the other drivers in this same directory.
	*
	* http://www.semiconductors.philips.com/acrobat/datasheets/PCF8563-04.pdf
	*/

	#include <linux/clk-provider.h>
	#include <linux/i2c.h>
	#include <linux/bcd.h>
	#include <linux/rtc.h>
	#include <linux/slab.h>
	#include <linux/module.h>
	#include <linux/of.h>
	#include <linux/err.h>

	#define PCF8563_REG_ST1 0x00 /* status */
	#define PCF8563_REG_ST2 0x01
	#define PCF8563_BIT_AIE (1 << 1)
	#define PCF8563_BIT_AF (1 << 3)
	#define PCF8563_BITS_ST2_N (7 << 5)

	#define PCF8563_REG_SC 0x02 /* datetime */
	#define PCF8563_REG_MN 0x03
	#define PCF8563_REG_HR 0x04
	#define PCF8563_REG_DM 0x05
	#define PCF8563_REG_DW 0x06
	#define PCF8563_REG_MO 0x07
	#define PCF8563_REG_YR 0x08

	#define PCF8563_REG_AMN 0x09 /* alarm */

	#define PCF8563_REG_CLKO 0x0D /* clock out */
	#define PCF8563_REG_CLKO_FE 0x80 /* clock out enabled */
	#define PCF8563_REG_CLKO_F_MASK 0x03 /* frequenc mask */
	#define PCF8563_REG_CLKO_F_32768HZ 0x00
	#define PCF8563_REG_CLKO_F_1024HZ 0x01
	#define PCF8563_REG_CLKO_F_32HZ 0x02
	#define PCF8563_REG_CLKO_F_1HZ 0x03

	#define PCF8563_REG_TMRC 0x0E /* timer control */
	#define PCF8563_TMRC_ENABLE BIT(7)
	#define PCF8563_TMRC_4096 0
	#define PCF8563_TMRC_64 1
	#define PCF8563_TMRC_1 2
	#define PCF8563_TMRC_1_60 3
	#define PCF8563_TMRC_MASK 3

	#define PCF8563_REG_TMR 0x0F /* timer */

	#define PCF8563_SC_LV 0x80 /* low voltage */
	#define PCF8563_MO_C 0x80 /* century */

	static struct i2c_driver pcf8563_driver;

	struct pcf8563 {
	struct rtc_device *rtc;
	/*
	* The meaning of MO_C bit varies by the chip type.
	* From PCF8563 datasheet: this bit is toggled when the years
	* register overflows from 99 to 00
	* 0 indicates the century is 20xx
	* 1 indicates the century is 19xx
	* From RTC8564 datasheet: this bit indicates change of
	* century. When the year digit data overflows from 99 to 00,
	* this bit is set. By presetting it to 0 while still in the
	* 20th century, it will be set in year 2000, ...
	* There seems no reliable way to know how the system use this
	* bit. So let's do it heuristically, assuming we are live in
	* 1970...2069.
	*/
	int c_polarity; /* 0: MO_C=1 means 19xx, otherwise MO_C=1 means 20xx */
	int voltage_low; /* incicates if a low_voltage was detected */

	struct i2c_client *client;
	#ifdef CONFIG_COMMON_CLK
	struct clk_hw clkout_hw;
	#endif
	};

	static int pcf8563_read_block_data(struct i2c_client *client, unsigned char reg,
	unsigned char length, unsigned char *buf)
	{
	struct i2c_msg msgs[] = {
	{/* setup read ptr */
	.addr = client->addr,
	.len = 1,
	.buf = &reg,
	},
	{
	.addr = client->addr,
	.flags = I2C_M_RD,
	.len = length,
	.buf = buf
	},
	};

	if ((i2c_transfer(client->adapter, msgs, 2)) != 2) {
	dev_err(&client->dev, "%s: read error\n", __func__);
	return -EIO;
	}

	return 0;
	}

	static int pcf8563_write_block_data(struct i2c_client *client,
	unsigned char reg, unsigned char length,
	unsigned char *buf)
	{
	int i, err;

	for (i = 0; i < length; i++) {
	unsigned char data[2] = { reg + i, buf[i] };

	err = i2c_master_send(client, data, sizeof(data));
	if (err != sizeof(data)) {
	dev_err(&client->dev,
	"%s: err=%d addr=%02x, data=%02x\n",
	__func__, err, data[0], data[1]);
	return -EIO;
	}
	}

	return 0;
	}

	static int pcf8563_set_alarm_mode(struct i2c_client *client, bool on)
	{
	unsigned char buf;
	int err;

	err = pcf8563_read_block_data(client, PCF8563_REG_ST2, 1, &buf);
	if (err < 0)
	return err;

	if (on)
	buf \|= PCF8563_BIT_AIE;
	else
	buf &= ~PCF8563_BIT_AIE;

	buf &= ~(PCF8563_BIT_AF \| PCF8563_BITS_ST2_N);

	err = pcf8563_write_block_data(client, PCF8563_REG_ST2, 1, &buf);
	if (err < 0) {
	dev_err(&client->dev, "%s: write error\n", __func__);
	return -EIO;
	}

	return 0;
	}

	static int pcf8563_get_alarm_mode(struct i2c_client client, unsigned char en,
	unsigned char *pen)
	{
	unsigned char buf;
	int err;

	err = pcf8563_read_block_data(client, PCF8563_REG_ST2, 1, &buf);
	if (err)
	return err;

	if (en)
	*en = !!(buf & PCF8563_BIT_AIE);
	if (pen)
	*pen = !!(buf & PCF8563_BIT_AF);

	return 0;
	}

	static irqreturn_t pcf8563_irq(int irq, void *dev_id)
	{
	struct pcf8563 *pcf8563 = i2c_get_clientdata(dev_id);
	int err;
	char pending;

	err = pcf8563_get_alarm_mode(pcf8563->client, NULL, &pending);
	if (err)
	return IRQ_NONE;

	if (pending) {
	rtc_update_irq(pcf8563->rtc, 1, RTC_IRQF \| RTC_AF);
	pcf8563_set_alarm_mode(pcf8563->client, 1);
	return IRQ_HANDLED;
	}

	return IRQ_NONE;
	}

	/*
	* In the routines that deal directly with the pcf8563 hardware, we use
	* rtc_time -- month 0-11, hour 0-23, yr = calendar year-epoch.
	*/
	static int pcf8563_rtc_read_time(struct device dev, struct rtc_time tm)
	{
	struct i2c_client *client = to_i2c_client(dev);
	struct pcf8563 *pcf8563 = i2c_get_clientdata(client);
	unsigned char buf[9];
	int err;

	err = pcf8563_read_block_data(client, PCF8563_REG_ST1, 9, buf);
	if (err)
	return err;

	if (buf[PCF8563_REG_SC] & PCF8563_SC_LV) {
	pcf8563->voltage_low = 1;
	dev_err(&client->dev,
	"low voltage detected, date/time is not reliable.\n");
	return -EINVAL;
	}

	dev_dbg(&client->dev,
	"%s: raw data is st1=%02x, st2=%02x, sec=%02x, min=%02x, hr=%02x, "
	"mday=%02x, wday=%02x, mon=%02x, year=%02x\n",
	__func__,
	buf[0], buf[1], buf[2], buf[3],
	buf[4], buf[5], buf[6], buf[7],
	buf[8]);


	tm->tm_sec = bcd2bin(buf[PCF8563_REG_SC] & 0x7F);
	tm->tm_min = bcd2bin(buf[PCF8563_REG_MN] & 0x7F);
	tm->tm_hour = bcd2bin(buf[PCF8563_REG_HR] & 0x3F); /* rtc hr 0-23 */
	tm->tm_mday = bcd2bin(buf[PCF8563_REG_DM] & 0x3F);
	tm->tm_wday = buf[PCF8563_REG_DW] & 0x07;
	tm->tm_mon = bcd2bin(buf[PCF8563_REG_MO] & 0x1F) - 1; /* rtc mn 1-12 */
	tm->tm_year = bcd2bin(buf[PCF8563_REG_YR]) + 100;
	/* detect the polarity heuristically. see note above. */
	pcf8563->c_polarity = (buf[PCF8563_REG_MO] & PCF8563_MO_C) ?
	(tm->tm_year >= 100) : (tm->tm_year < 100);

	dev_dbg(&client->dev, "%s: tm is secs=%d, mins=%d, hours=%d, "
	"mday=%d, mon=%d, year=%d, wday=%d\n",
	__func__,
	tm->tm_sec, tm->tm_min, tm->tm_hour,
	tm->tm_mday, tm->tm_mon, tm->tm_year, tm->tm_wday);

	return 0;
	}

	static int pcf8563_rtc_set_time(struct device dev, struct rtc_time tm)
	{
	struct i2c_client *client = to_i2c_client(dev);
	struct pcf8563 *pcf8563 = i2c_get_clientdata(client);
	unsigned char buf[9];

	dev_dbg(&client->dev, "%s: secs=%d, mins=%d, hours=%d, "
	"mday=%d, mon=%d, year=%d, wday=%d\n",
	__func__,
	tm->tm_sec, tm->tm_min, tm->tm_hour,
	tm->tm_mday, tm->tm_mon, tm->tm_year, tm->tm_wday);

	/* hours, minutes and seconds */
	buf[PCF8563_REG_SC] = bin2bcd(tm->tm_sec);
	buf[PCF8563_REG_MN] = bin2bcd(tm->tm_min);
	buf[PCF8563_REG_HR] = bin2bcd(tm->tm_hour);

	buf[PCF8563_REG_DM] = bin2bcd(tm->tm_mday);

	/* month, 1 - 12 */
	buf[PCF8563_REG_MO] = bin2bcd(tm->tm_mon + 1);

	/* year and century */
	buf[PCF8563_REG_YR] = bin2bcd(tm->tm_year - 100);
	if (pcf8563->c_polarity ? (tm->tm_year >= 100) : (tm->tm_year < 100))
	buf[PCF8563_REG_MO] \|= PCF8563_MO_C;

	buf[PCF8563_REG_DW] = tm->tm_wday & 0x07;

	return pcf8563_write_block_data(client, PCF8563_REG_SC,
	9 - PCF8563_REG_SC, buf + PCF8563_REG_SC);
	}

	#ifdef CONFIG_RTC_INTF_DEV
	static int pcf8563_rtc_ioctl(struct device *dev, unsigned int cmd, unsigned long arg)
	{
	struct pcf8563 *pcf8563 = i2c_get_clientdata(to_i2c_client(dev));
	struct rtc_time tm;

	switch (cmd) {
	case RTC_VL_READ:
	if (pcf8563->voltage_low)
	dev_info(dev, "low voltage detected, date/time is not reliable.\n");

	if (copy_to_user((void __user *)arg, &pcf8563->voltage_low,
	sizeof(int)))
	return -EFAULT;
	return 0;
	case RTC_VL_CLR:
	/*
	* Clear the VL bit in the seconds register in case
	* the time has not been set already (which would
	* have cleared it). This does not really matter
	* because of the cached voltage_low value but do it
	* anyway for consistency.
	*/
	if (pcf8563_rtc_read_time(dev, &tm))
	pcf8563_rtc_set_time(dev, &tm);

	/* Clear the cached value. */
	pcf8563->voltage_low = 0;

	return 0;
	default:
	return -ENOIOCTLCMD;
	}
	}
	#else
	#define pcf8563_rtc_ioctl NULL
	#endif

	static int pcf8563_rtc_read_alarm(struct device dev, struct rtc_wkalrm tm)
	{
	struct i2c_client *client = to_i2c_client(dev);
	unsigned char buf[4];
	int err;

	err = pcf8563_read_block_data(client, PCF8563_REG_AMN, 4, buf);
	if (err)
	return err;

	dev_dbg(&client->dev,
	"%s: raw data is min=%02x, hr=%02x, mday=%02x, wday=%02x\n",
	__func__, buf[0], buf[1], buf[2], buf[3]);

	tm->time.tm_sec = 0;
	tm->time.tm_min = bcd2bin(buf[0] & 0x7F);
	tm->time.tm_hour = bcd2bin(buf[1] & 0x3F);
	tm->time.tm_mday = bcd2bin(buf[2] & 0x3F);
	tm->time.tm_wday = bcd2bin(buf[3] & 0x7);

	err = pcf8563_get_alarm_mode(client, &tm->enabled, &tm->pending);
	if (err < 0)
	return err;

	dev_dbg(&client->dev, "%s: tm is mins=%d, hours=%d, mday=%d, wday=%d,"
	" enabled=%d, pending=%d\n", __func__, tm->time.tm_min,
	tm->time.tm_hour, tm->time.tm_mday, tm->time.tm_wday,
	tm->enabled, tm->pending);

	return 0;
	}

	static int pcf8563_rtc_set_alarm(struct device dev, struct rtc_wkalrm tm)
	{
	struct i2c_client *client = to_i2c_client(dev);
	unsigned char buf[4];
	int err;

	/* The alarm has no seconds, round up to nearest minute */
	if (tm->time.tm_sec) {
	time64_t alarm_time = rtc_tm_to_time64(&tm->time);

	alarm_time += 60 - tm->time.tm_sec;
	rtc_time64_to_tm(alarm_time, &tm->time);
	}

	dev_dbg(dev, "%s, min=%d hour=%d wday=%d mday=%d "
	"enabled=%d pending=%d\n", __func__,
	tm->time.tm_min, tm->time.tm_hour, tm->time.tm_wday,
	tm->time.tm_mday, tm->enabled, tm->pending);

	buf[0] = bin2bcd(tm->time.tm_min);
	buf[1] = bin2bcd(tm->time.tm_hour);
	buf[2] = bin2bcd(tm->time.tm_mday);
	buf[3] = tm->time.tm_wday & 0x07;

	err = pcf8563_write_block_data(client, PCF8563_REG_AMN, 4, buf);
	if (err)
	return err;

	return pcf8563_set_alarm_mode(client, !!tm->enabled);
	}

	static int pcf8563_irq_enable(struct device *dev, unsigned int enabled)
	{
	dev_dbg(dev, "%s: en=%d\n", __func__, enabled);
	return pcf8563_set_alarm_mode(to_i2c_client(dev), !!enabled);
	}

	#ifdef CONFIG_COMMON_CLK
	/*
	* Handling of the clkout
	*/

	#define clkout_hw_to_pcf8563(_hw) container_of(_hw, struct pcf8563, clkout_hw)

	static const int clkout_rates[] = {
	32768,
	1024,
	32,
	1,
	};

	static unsigned long pcf8563_clkout_recalc_rate(struct clk_hw *hw,
	unsigned long parent_rate)
	{
	struct pcf8563 *pcf8563 = clkout_hw_to_pcf8563(hw);
	struct i2c_client *client = pcf8563->client;
	unsigned char buf;
	int ret = pcf8563_read_block_data(client, PCF8563_REG_CLKO, 1, &buf);

	if (ret < 0)
	return 0;

	buf &= PCF8563_REG_CLKO_F_MASK;
	return clkout_rates[buf];
	}

	static long pcf8563_clkout_round_rate(struct clk_hw *hw, unsigned long rate,
	unsigned long *prate)
	{
	int i;

	for (i = 0; i < ARRAY_SIZE(clkout_rates); i++)
	if (clkout_rates[i] <= rate)
	return clkout_rates[i];

	return 0;
	}

	static int pcf8563_clkout_set_rate(struct clk_hw *hw, unsigned long rate,
	unsigned long parent_rate)
	{
	struct pcf8563 *pcf8563 = clkout_hw_to_pcf8563(hw);
	struct i2c_client *client = pcf8563->client;
	unsigned char buf;
	int ret = pcf8563_read_block_data(client, PCF8563_REG_CLKO, 1, &buf);
	int i;

	if (ret < 0)
	return ret;

	for (i = 0; i < ARRAY_SIZE(clkout_rates); i++)
	if (clkout_rates[i] == rate) {
	buf &= ~PCF8563_REG_CLKO_F_MASK;
	buf \|= i;
	ret = pcf8563_write_block_data(client,
	PCF8563_REG_CLKO, 1,
	&buf);
	return ret;
	}

	return -EINVAL;
	}

	static int pcf8563_clkout_control(struct clk_hw *hw, bool enable)
	{
	struct pcf8563 *pcf8563 = clkout_hw_to_pcf8563(hw);
	struct i2c_client *client = pcf8563->client;
	unsigned char buf;
	int ret = pcf8563_read_block_data(client, PCF8563_REG_CLKO, 1, &buf);

	if (ret < 0)
	return ret;

	if (enable)
	buf \|= PCF8563_REG_CLKO_FE;
	else
	buf &= ~PCF8563_REG_CLKO_FE;

	ret = pcf8563_write_block_data(client, PCF8563_REG_CLKO, 1, &buf);
	return ret;
	}

	static int pcf8563_clkout_prepare(struct clk_hw *hw)
	{
	return pcf8563_clkout_control(hw, 1);
	}

	static void pcf8563_clkout_unprepare(struct clk_hw *hw)
	{
	pcf8563_clkout_control(hw, 0);
	}

	static int pcf8563_clkout_is_prepared(struct clk_hw *hw)
	{
	struct pcf8563 *pcf8563 = clkout_hw_to_pcf8563(hw);
	struct i2c_client *client = pcf8563->client;
	unsigned char buf;
	int ret = pcf8563_read_block_data(client, PCF8563_REG_CLKO, 1, &buf);

	if (ret < 0)
	return ret;

	return !!(buf & PCF8563_REG_CLKO_FE);
	}

	static const struct clk_ops pcf8563_clkout_ops = {
	.prepare = pcf8563_clkout_prepare,
	.unprepare = pcf8563_clkout_unprepare,
	.is_prepared = pcf8563_clkout_is_prepared,
	.recalc_rate = pcf8563_clkout_recalc_rate,
	.round_rate = pcf8563_clkout_round_rate,
	.set_rate = pcf8563_clkout_set_rate,
	};

	static struct clk pcf8563_clkout_register_clk(struct pcf8563 pcf8563)
	{
	struct i2c_client *client = pcf8563->client;
	struct device_node *node = client->dev.of_node;
	struct clk *clk;
	struct clk_init_data init;
	int ret;
	unsigned char buf;

	/* disable the clkout output */
	buf = 0;
	ret = pcf8563_write_block_data(client, PCF8563_REG_CLKO, 1, &buf);
	if (ret < 0)
	return ERR_PTR(ret);

	init.name = "pcf8563-clkout";
	init.ops = &pcf8563_clkout_ops;
	init.flags = 0;
	init.parent_names = NULL;
	init.num_parents = 0;
	pcf8563->clkout_hw.init = &init;

	/* optional override of the clockname */
	of_property_read_string(node, "clock-output-names", &init.name);

	/* register the clock */
	clk = devm_clk_register(&client->dev, &pcf8563->clkout_hw);

	if (!IS_ERR(clk))
	of_clk_add_provider(node, of_clk_src_simple_get, clk);

	return clk;
	}
	#endif

	static const struct rtc_class_ops pcf8563_rtc_ops = {
	.ioctl = pcf8563_rtc_ioctl,
	.read_time = pcf8563_rtc_read_time,
	.set_time = pcf8563_rtc_set_time,
	.read_alarm = pcf8563_rtc_read_alarm,
	.set_alarm = pcf8563_rtc_set_alarm,
	.alarm_irq_enable = pcf8563_irq_enable,
	};

	static int pcf8563_probe(struct i2c_client *client,
	const struct i2c_device_id *id)
	{
	struct pcf8563 *pcf8563;
	int err;
	unsigned char buf;

	dev_dbg(&client->dev, "%s\n", __func__);

	if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C))
	return -ENODEV;

	pcf8563 = devm_kzalloc(&client->dev, sizeof(struct pcf8563),
	GFP_KERNEL);
	if (!pcf8563)
	return -ENOMEM;

	i2c_set_clientdata(client, pcf8563);
	pcf8563->client = client;
	device_set_wakeup_capable(&client->dev, 1);

	/* Set timer to lowest frequency to save power (ref Haoyu datasheet) */
	buf = PCF8563_TMRC_1_60;
	err = pcf8563_write_block_data(client, PCF8563_REG_TMRC, 1, &buf);
	if (err < 0) {
	dev_err(&client->dev, "%s: write error\n", __func__);
	return err;
	}

	/* Clear flags and disable interrupts */
	buf = 0;
	err = pcf8563_write_block_data(client, PCF8563_REG_ST2, 1, &buf);
	if (err < 0) {
	dev_err(&client->dev, "%s: write error\n", __func__);
	return err;
	}

	pcf8563->rtc = devm_rtc_allocate_device(&client->dev);
	if (IS_ERR(pcf8563->rtc))
	return PTR_ERR(pcf8563->rtc);

	pcf8563->rtc->ops = &pcf8563_rtc_ops;
	/* the pcf8563 alarm only supports a minute accuracy */
	pcf8563->rtc->uie_unsupported = 1;
	pcf8563->rtc->range_min = RTC_TIMESTAMP_BEGIN_2000;
	pcf8563->rtc->range_max = RTC_TIMESTAMP_END_2099;
	pcf8563->rtc->set_start_time = true;

	if (client->irq > 0) {
	err = devm_request_threaded_irq(&client->dev, client->irq,
	NULL, pcf8563_irq,
	IRQF_SHARED \| IRQF_ONESHOT \| IRQF_TRIGGER_LOW,
	pcf8563_driver.driver.name, client);
	if (err) {
	dev_err(&client->dev, "unable to request IRQ %d\n",
	client->irq);
	return err;
	}
	}

	err = rtc_register_device(pcf8563->rtc);
	if (err)
	return err;

	#ifdef CONFIG_COMMON_CLK
	/* register clk in common clk framework */
	pcf8563_clkout_register_clk(pcf8563);
	#endif

	return 0;
	}

	static const struct i2c_device_id pcf8563_id[] = {
	{ "pcf8563", 0 },
	{ "rtc8564", 0 },
	{ }
	};
	MODULE_DEVICE_TABLE(i2c, pcf8563_id);

	#ifdef CONFIG_OF
	static const struct of_device_id pcf8563_of_match[] = {
	{ .compatible = "nxp,pcf8563" },
	{ .compatible = "epson,rtc8564" },
	{ .compatible = "microcrystal,rv8564" },
	{}
	};
	MODULE_DEVICE_TABLE(of, pcf8563_of_match);
	#endif

	static struct i2c_driver pcf8563_driver = {
	.driver = {
	.name = "rtc-pcf8563",
	.of_match_table = of_match_ptr(pcf8563_of_match),
	},
	.probe = pcf8563_probe,
	.id_table = pcf8563_id,
	};

	module_i2c_driver(pcf8563_driver);

	MODULE_AUTHOR("Alessandro Zummo <a.zummo@towertech.it>");
	MODULE_DESCRIPTION("Philips PCF8563/Epson RTC8564 RTC driver");
	MODULE_LICENSE("GPL");