drivers/rtc/rtc-pcf2123.c - kernel/mindspeed - Git at Google

 /*
  * An SPI driver for the Philips PCF2123 RTC
  * Copyright 2009 Cyber Switching, Inc.
  *
  * Author: Chris Verges <chrisv@cyberswitching.com>
  * Maintainers: http://www.cyberswitching.com
  *
  * based on the RS5C348 driver in this same directory.
  *
  * Thanks to Christian Pellegrin <chripell@fsfe.org> for
  * the sysfs contributions to this driver.
  *
  * 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.
  *
  * Please note that the CS is active high, so platform data
  * should look something like:
  *
  * static struct spi_board_info ek_spi_devices[] = {
  * 	...
  * 	{
  * 		.modalias		= "rtc-pcf2123",
  * 		.chip_select		= 1,
  * 		.controller_data	= (void *)AT91_PIN_PA10,
  *		.max_speed_hz		= 1000 * 1000,
  *		.mode			= SPI_CS_HIGH,
  *		.bus_num		= 0,
  *	},
  *	...
  *};
  *
  */

 #include <linux/bcd.h>
 #include <linux/delay.h>
 #include <linux/device.h>
 #include <linux/errno.h>
 #include <linux/init.h>
 #include <linux/kernel.h>
 #include <linux/string.h>
 #include <linux/slab.h>
 #include <linux/rtc.h>
 #include <linux/spi/spi.h>
 #include <linux/module.h>

 #define DRV_VERSION "0.6"

 #define PCF2123_REG_CTRL1	(0x00)	/* Control Register 1 */
 #define PCF2123_REG_CTRL2	(0x01)	/* Control Register 2 */
 #define PCF2123_REG_SC		(0x02)	/* datetime */
 #define PCF2123_REG_MN		(0x03)
 #define PCF2123_REG_HR		(0x04)
 #define PCF2123_REG_DM		(0x05)
 #define PCF2123_REG_DW		(0x06)
 #define PCF2123_REG_MO		(0x07)
 #define PCF2123_REG_YR		(0x08)

 #define PCF2123_SUBADDR		(1 << 4)
 #define PCF2123_WRITE		((0 << 7) | PCF2123_SUBADDR)
 #define PCF2123_READ		((1 << 7) | PCF2123_SUBADDR)

 static struct spi_driver pcf2123_driver;

 struct pcf2123_sysfs_reg {
 	struct device_attribute attr;
 	char name[2];
 };

 struct pcf2123_plat_data {
 	struct rtc_device *rtc;
 	struct pcf2123_sysfs_reg regs[16];
 };

 /*
  * Causes a 30 nanosecond delay to ensure that the PCF2123 chip select
  * is released properly after an SPI write.  This function should be
  * called after EVERY read/write call over SPI.
  */
 static inline void pcf2123_delay_trec(void)
 {
 	ndelay(30);
 }

 static ssize_t pcf2123_show(struct device *dev, struct device_attribute *attr,
 			    char *buffer)
 {
 	struct spi_device *spi = to_spi_device(dev);
 	struct pcf2123_sysfs_reg *r;
 	u8 txbuf[1], rxbuf[1];
 	unsigned long reg;
 	int ret;

 	r = container_of(attr, struct pcf2123_sysfs_reg, attr);

 	if (strict_strtoul(r->name, 16, &reg))
 		return -EINVAL;

 	txbuf[0] = PCF2123_READ | reg;
 	ret = spi_write_then_read(spi, txbuf, 1, rxbuf, 1);
 	if (ret < 0)
 		return -EIO;
 	pcf2123_delay_trec();
 	return sprintf(buffer, "0x%x\n", rxbuf[0]);
 }

 static ssize_t pcf2123_store(struct device *dev, struct device_attribute *attr,
 			     const char *buffer, size_t count) {
 	struct spi_device *spi = to_spi_device(dev);
 	struct pcf2123_sysfs_reg *r;
 	u8 txbuf[2];
 	unsigned long reg;
 	unsigned long val;

 	int ret;

 	r = container_of(attr, struct pcf2123_sysfs_reg, attr);

 	if (strict_strtoul(r->name, 16, &reg)
 		|| strict_strtoul(buffer, 10, &val))
 		return -EINVAL;

 	txbuf[0] = PCF2123_WRITE | reg;
 	txbuf[1] = val;
 	ret = spi_write(spi, txbuf, sizeof(txbuf));
 	if (ret < 0)
 		return -EIO;
 	pcf2123_delay_trec();
 	return count;
 }

 static int pcf2123_rtc_read_time(struct device *dev, struct rtc_time *tm)
 {
 	struct spi_device *spi = to_spi_device(dev);
 	u8 txbuf[1], rxbuf[7];
 	int ret;

 	txbuf[0] = PCF2123_READ | PCF2123_REG_SC;
 	ret = spi_write_then_read(spi, txbuf, sizeof(txbuf),
 			rxbuf, sizeof(rxbuf));
 	if (ret < 0)
 		return ret;
 	pcf2123_delay_trec();

 	tm->tm_sec = bcd2bin(rxbuf[0] & 0x7F);
 	tm->tm_min = bcd2bin(rxbuf[1] & 0x7F);
 	tm->tm_hour = bcd2bin(rxbuf[2] & 0x3F); /* rtc hr 0-23 */
 	tm->tm_mday = bcd2bin(rxbuf[3] & 0x3F);
 	tm->tm_wday = rxbuf[4] & 0x07;
 	tm->tm_mon = bcd2bin(rxbuf[5] & 0x1F) - 1; /* rtc mn 1-12 */
 	tm->tm_year = bcd2bin(rxbuf[6]);
 	if (tm->tm_year < 70)
 		tm->tm_year += 100;	/* assume we are in 1970...2069 */

 	dev_dbg(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);

 	/* the clock can give out invalid datetime, but we cannot return
 	 * -EINVAL otherwise hwclock will refuse to set the time on bootup.
 	 */
 	if (rtc_valid_tm(tm) < 0)
 		dev_err(dev, "retrieved date/time is not valid.\n");

 	return 0;
 }

 static int pcf2123_rtc_set_time(struct device *dev, struct rtc_time *tm)
 {
 	struct spi_device *spi = to_spi_device(dev);
 	u8 txbuf[8];
 	int ret;

 	dev_dbg(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);

 	/* Stop the counter first */
 	txbuf[0] = PCF2123_WRITE | PCF2123_REG_CTRL1;
 	txbuf[1] = 0x20;
 	ret = spi_write(spi, txbuf, 2);
 	if (ret < 0)
 		return ret;
 	pcf2123_delay_trec();

 	/* Set the new time */
 	txbuf[0] = PCF2123_WRITE | PCF2123_REG_SC;
 	txbuf[1] = bin2bcd(tm->tm_sec & 0x7F);
 	txbuf[2] = bin2bcd(tm->tm_min & 0x7F);
 	txbuf[3] = bin2bcd(tm->tm_hour & 0x3F);
 	txbuf[4] = bin2bcd(tm->tm_mday & 0x3F);
 	txbuf[5] = tm->tm_wday & 0x07;
 	txbuf[6] = bin2bcd((tm->tm_mon + 1) & 0x1F); /* rtc mn 1-12 */
 	txbuf[7] = bin2bcd(tm->tm_year < 100 ? tm->tm_year : tm->tm_year - 100);

 	ret = spi_write(spi, txbuf, sizeof(txbuf));
 	if (ret < 0)
 		return ret;
 	pcf2123_delay_trec();

 	/* Start the counter */
 	txbuf[0] = PCF2123_WRITE | PCF2123_REG_CTRL1;
 	txbuf[1] = 0x00;
 	ret = spi_write(spi, txbuf, 2);
 	if (ret < 0)
 		return ret;
 	pcf2123_delay_trec();

 	return 0;
 }

 static const struct rtc_class_ops pcf2123_rtc_ops = {
 	.read_time	= pcf2123_rtc_read_time,
 	.set_time	= pcf2123_rtc_set_time,
 };

 static int __devinit pcf2123_probe(struct spi_device *spi)
 {
 	struct rtc_device *rtc;
 	struct pcf2123_plat_data *pdata;
 	u8 txbuf[2], rxbuf[2];
 	int ret, i;

 	pdata = kzalloc(sizeof(struct pcf2123_plat_data), GFP_KERNEL);
 	if (!pdata)
 		return -ENOMEM;
 	spi->dev.platform_data = pdata;

 	/* Send a software reset command */
 	txbuf[0] = PCF2123_WRITE | PCF2123_REG_CTRL1;
 	txbuf[1] = 0x58;
 	dev_dbg(&spi->dev, "resetting RTC (0x%02X 0x%02X)\n",
 			txbuf[0], txbuf[1]);
 	ret = spi_write(spi, txbuf, 2 * sizeof(u8));
 	if (ret < 0)
 		goto kfree_exit;
 	pcf2123_delay_trec();

 	/* Stop the counter */
 	txbuf[0] = PCF2123_WRITE | PCF2123_REG_CTRL1;
 	txbuf[1] = 0x20;
 	dev_dbg(&spi->dev, "stopping RTC (0x%02X 0x%02X)\n",
 			txbuf[0], txbuf[1]);
 	ret = spi_write(spi, txbuf, 2 * sizeof(u8));
 	if (ret < 0)
 		goto kfree_exit;
 	pcf2123_delay_trec();

 	/* See if the counter was actually stopped */
 	txbuf[0] = PCF2123_READ | PCF2123_REG_CTRL1;
 	dev_dbg(&spi->dev, "checking for presence of RTC (0x%02X)\n",
 			txbuf[0]);
 	ret = spi_write_then_read(spi, txbuf, 1 * sizeof(u8),
 					rxbuf, 2 * sizeof(u8));
 	dev_dbg(&spi->dev, "received data from RTC (0x%02X 0x%02X)\n",
 			rxbuf[0], rxbuf[1]);
 	if (ret < 0)
 		goto kfree_exit;
 	pcf2123_delay_trec();

 	if (!(rxbuf[0] & 0x20)) {
 		dev_err(&spi->dev, "chip not found\n");
 		goto kfree_exit;
 	}

 	dev_info(&spi->dev, "chip found, driver version " DRV_VERSION "\n");
 	dev_info(&spi->dev, "spiclk %u KHz.\n",
 			(spi->max_speed_hz + 500) / 1000);

 	/* Start the counter */
 	txbuf[0] = PCF2123_WRITE | PCF2123_REG_CTRL1;
 	txbuf[1] = 0x00;
 	ret = spi_write(spi, txbuf, sizeof(txbuf));
 	if (ret < 0)
 		goto kfree_exit;
 	pcf2123_delay_trec();

 	/* Finalize the initialization */
 	rtc = rtc_device_register(pcf2123_driver.driver.name, &spi->dev,
 			&pcf2123_rtc_ops, THIS_MODULE);

 	if (IS_ERR(rtc)) {
 		dev_err(&spi->dev, "failed to register.\n");
 		ret = PTR_ERR(rtc);
 		goto kfree_exit;
 	}

 	pdata->rtc = rtc;

 	for (i = 0; i < 16; i++) {
 		sprintf(pdata->regs[i].name, "%1x", i);
 		pdata->regs[i].attr.attr.mode = S_IRUGO | S_IWUSR;
 		pdata->regs[i].attr.attr.name = pdata->regs[i].name;
 		pdata->regs[i].attr.show = pcf2123_show;
 		pdata->regs[i].attr.store = pcf2123_store;
 		ret = device_create_file(&spi->dev, &pdata->regs[i].attr);
 		if (ret) {
 			dev_err(&spi->dev, "Unable to create sysfs %s\n",
 				pdata->regs[i].name);
 			goto sysfs_exit;
 		}
 	}

 	return 0;

 sysfs_exit:
 	for (i--; i >= 0; i--)
 		device_remove_file(&spi->dev, &pdata->regs[i].attr);

 kfree_exit:
 	kfree(pdata);
 	spi->dev.platform_data = NULL;
 	return ret;
 }

 static int __devexit pcf2123_remove(struct spi_device *spi)
 {
 	struct pcf2123_plat_data *pdata = spi->dev.platform_data;
 	int i;

 	if (pdata) {
 		struct rtc_device *rtc = pdata->rtc;

 		if (rtc)
 			rtc_device_unregister(rtc);
 		for (i = 0; i < 16; i++)
 			if (pdata->regs[i].name[0])
 				device_remove_file(&spi->dev,
 						   &pdata->regs[i].attr);
 		kfree(pdata);
 	}

 	return 0;
 }

 static struct spi_driver pcf2123_driver = {
 	.driver	= {
 			.name	= "rtc-pcf2123",
 			.bus	= &spi_bus_type,
 			.owner	= THIS_MODULE,
 	},
 	.probe	= pcf2123_probe,
 	.remove	= __devexit_p(pcf2123_remove),
 };

 static int __init pcf2123_init(void)
 {
 	return spi_register_driver(&pcf2123_driver);
 }

 static void __exit pcf2123_exit(void)
 {
 	spi_unregister_driver(&pcf2123_driver);
 }

 MODULE_AUTHOR("Chris Verges <chrisv@cyberswitching.com>");
 MODULE_DESCRIPTION("NXP PCF2123 RTC driver");
 MODULE_LICENSE("GPL");
 MODULE_VERSION(DRV_VERSION);

 module_init(pcf2123_init);
 module_exit(pcf2123_exit);
	/*
	* An SPI driver for the Philips PCF2123 RTC
	* Copyright 2009 Cyber Switching, Inc.
	*
	* Author: Chris Verges <chrisv@cyberswitching.com>
	* Maintainers: http://www.cyberswitching.com
	*
	* based on the RS5C348 driver in this same directory.
	*
	* Thanks to Christian Pellegrin <chripell@fsfe.org> for
	* the sysfs contributions to this driver.
	*
	* 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.
	*
	* Please note that the CS is active high, so platform data
	* should look something like:
	*
	* static struct spi_board_info ek_spi_devices[] = {
	* ...
	* {
	* .modalias = "rtc-pcf2123",
	* .chip_select = 1,
	* .controller_data = (void *)AT91_PIN_PA10,
	* .max_speed_hz = 1000 * 1000,
	* .mode = SPI_CS_HIGH,
	* .bus_num = 0,
	* },
	* ...
	*};
	*
	*/

	#include <linux/bcd.h>
	#include <linux/delay.h>
	#include <linux/device.h>
	#include <linux/errno.h>
	#include <linux/init.h>
	#include <linux/kernel.h>
	#include <linux/string.h>
	#include <linux/slab.h>
	#include <linux/rtc.h>
	#include <linux/spi/spi.h>
	#include <linux/module.h>

	#define DRV_VERSION "0.6"

	#define PCF2123_REG_CTRL1 (0x00) /* Control Register 1 */
	#define PCF2123_REG_CTRL2 (0x01) /* Control Register 2 */
	#define PCF2123_REG_SC (0x02) /* datetime */
	#define PCF2123_REG_MN (0x03)
	#define PCF2123_REG_HR (0x04)
	#define PCF2123_REG_DM (0x05)
	#define PCF2123_REG_DW (0x06)
	#define PCF2123_REG_MO (0x07)
	#define PCF2123_REG_YR (0x08)

	#define PCF2123_SUBADDR (1 << 4)
	#define PCF2123_WRITE ((0 << 7) \| PCF2123_SUBADDR)
	#define PCF2123_READ ((1 << 7) \| PCF2123_SUBADDR)

	static struct spi_driver pcf2123_driver;

	struct pcf2123_sysfs_reg {
	struct device_attribute attr;
	char name[2];
	};

	struct pcf2123_plat_data {
	struct rtc_device *rtc;
	struct pcf2123_sysfs_reg regs[16];
	};

	/*
	* Causes a 30 nanosecond delay to ensure that the PCF2123 chip select
	* is released properly after an SPI write. This function should be
	* called after EVERY read/write call over SPI.
	*/
	static inline void pcf2123_delay_trec(void)
	{
	ndelay(30);
	}

	static ssize_t pcf2123_show(struct device dev, struct device_attribute attr,
	char *buffer)
	{
	struct spi_device *spi = to_spi_device(dev);
	struct pcf2123_sysfs_reg *r;
	u8 txbuf[1], rxbuf[1];
	unsigned long reg;
	int ret;

	r = container_of(attr, struct pcf2123_sysfs_reg, attr);

	if (strict_strtoul(r->name, 16, &reg))
	return -EINVAL;

	txbuf[0] = PCF2123_READ \| reg;
	ret = spi_write_then_read(spi, txbuf, 1, rxbuf, 1);
	if (ret < 0)
	return -EIO;
	pcf2123_delay_trec();
	return sprintf(buffer, "0x%x\n", rxbuf[0]);
	}

	static ssize_t pcf2123_store(struct device dev, struct device_attribute attr,
	const char *buffer, size_t count) {
	struct spi_device *spi = to_spi_device(dev);
	struct pcf2123_sysfs_reg *r;
	u8 txbuf[2];
	unsigned long reg;
	unsigned long val;

	int ret;

	r = container_of(attr, struct pcf2123_sysfs_reg, attr);

	if (strict_strtoul(r->name, 16, &reg)
	\|\| strict_strtoul(buffer, 10, &val))
	return -EINVAL;

	txbuf[0] = PCF2123_WRITE \| reg;
	txbuf[1] = val;
	ret = spi_write(spi, txbuf, sizeof(txbuf));
	if (ret < 0)
	return -EIO;
	pcf2123_delay_trec();
	return count;
	}

	static int pcf2123_rtc_read_time(struct device dev, struct rtc_time tm)
	{
	struct spi_device *spi = to_spi_device(dev);
	u8 txbuf[1], rxbuf[7];
	int ret;

	txbuf[0] = PCF2123_READ \| PCF2123_REG_SC;
	ret = spi_write_then_read(spi, txbuf, sizeof(txbuf),
	rxbuf, sizeof(rxbuf));
	if (ret < 0)
	return ret;
	pcf2123_delay_trec();

	tm->tm_sec = bcd2bin(rxbuf[0] & 0x7F);
	tm->tm_min = bcd2bin(rxbuf[1] & 0x7F);
	tm->tm_hour = bcd2bin(rxbuf[2] & 0x3F); /* rtc hr 0-23 */
	tm->tm_mday = bcd2bin(rxbuf[3] & 0x3F);
	tm->tm_wday = rxbuf[4] & 0x07;
	tm->tm_mon = bcd2bin(rxbuf[5] & 0x1F) - 1; /* rtc mn 1-12 */
	tm->tm_year = bcd2bin(rxbuf[6]);
	if (tm->tm_year < 70)
	tm->tm_year += 100; /* assume we are in 1970...2069 */

	dev_dbg(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);

	/* the clock can give out invalid datetime, but we cannot return
	* -EINVAL otherwise hwclock will refuse to set the time on bootup.
	*/
	if (rtc_valid_tm(tm) < 0)
	dev_err(dev, "retrieved date/time is not valid.\n");

	return 0;
	}

	static int pcf2123_rtc_set_time(struct device dev, struct rtc_time tm)
	{
	struct spi_device *spi = to_spi_device(dev);
	u8 txbuf[8];
	int ret;

	dev_dbg(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);

	/* Stop the counter first */
	txbuf[0] = PCF2123_WRITE \| PCF2123_REG_CTRL1;
	txbuf[1] = 0x20;
	ret = spi_write(spi, txbuf, 2);
	if (ret < 0)
	return ret;
	pcf2123_delay_trec();

	/* Set the new time */
	txbuf[0] = PCF2123_WRITE \| PCF2123_REG_SC;
	txbuf[1] = bin2bcd(tm->tm_sec & 0x7F);
	txbuf[2] = bin2bcd(tm->tm_min & 0x7F);
	txbuf[3] = bin2bcd(tm->tm_hour & 0x3F);
	txbuf[4] = bin2bcd(tm->tm_mday & 0x3F);
	txbuf[5] = tm->tm_wday & 0x07;
	txbuf[6] = bin2bcd((tm->tm_mon + 1) & 0x1F); /* rtc mn 1-12 */
	txbuf[7] = bin2bcd(tm->tm_year < 100 ? tm->tm_year : tm->tm_year - 100);

	ret = spi_write(spi, txbuf, sizeof(txbuf));
	if (ret < 0)
	return ret;
	pcf2123_delay_trec();

	/* Start the counter */
	txbuf[0] = PCF2123_WRITE \| PCF2123_REG_CTRL1;
	txbuf[1] = 0x00;
	ret = spi_write(spi, txbuf, 2);
	if (ret < 0)
	return ret;
	pcf2123_delay_trec();

	return 0;
	}

	static const struct rtc_class_ops pcf2123_rtc_ops = {
	.read_time = pcf2123_rtc_read_time,
	.set_time = pcf2123_rtc_set_time,
	};

	static int __devinit pcf2123_probe(struct spi_device *spi)
	{
	struct rtc_device *rtc;
	struct pcf2123_plat_data *pdata;
	u8 txbuf[2], rxbuf[2];
	int ret, i;

	pdata = kzalloc(sizeof(struct pcf2123_plat_data), GFP_KERNEL);
	if (!pdata)
	return -ENOMEM;
	spi->dev.platform_data = pdata;

	/* Send a software reset command */
	txbuf[0] = PCF2123_WRITE \| PCF2123_REG_CTRL1;
	txbuf[1] = 0x58;
	dev_dbg(&spi->dev, "resetting RTC (0x%02X 0x%02X)\n",
	txbuf[0], txbuf[1]);
	ret = spi_write(spi, txbuf, 2 * sizeof(u8));
	if (ret < 0)
	goto kfree_exit;
	pcf2123_delay_trec();

	/* Stop the counter */
	txbuf[0] = PCF2123_WRITE \| PCF2123_REG_CTRL1;
	txbuf[1] = 0x20;
	dev_dbg(&spi->dev, "stopping RTC (0x%02X 0x%02X)\n",
	txbuf[0], txbuf[1]);
	ret = spi_write(spi, txbuf, 2 * sizeof(u8));
	if (ret < 0)
	goto kfree_exit;
	pcf2123_delay_trec();

	/* See if the counter was actually stopped */
	txbuf[0] = PCF2123_READ \| PCF2123_REG_CTRL1;
	dev_dbg(&spi->dev, "checking for presence of RTC (0x%02X)\n",
	txbuf[0]);
	ret = spi_write_then_read(spi, txbuf, 1 * sizeof(u8),
	rxbuf, 2 * sizeof(u8));
	dev_dbg(&spi->dev, "received data from RTC (0x%02X 0x%02X)\n",
	rxbuf[0], rxbuf[1]);
	if (ret < 0)
	goto kfree_exit;
	pcf2123_delay_trec();

	if (!(rxbuf[0] & 0x20)) {
	dev_err(&spi->dev, "chip not found\n");
	goto kfree_exit;
	}

	dev_info(&spi->dev, "chip found, driver version " DRV_VERSION "\n");
	dev_info(&spi->dev, "spiclk %u KHz.\n",
	(spi->max_speed_hz + 500) / 1000);

	/* Start the counter */
	txbuf[0] = PCF2123_WRITE \| PCF2123_REG_CTRL1;
	txbuf[1] = 0x00;
	ret = spi_write(spi, txbuf, sizeof(txbuf));
	if (ret < 0)
	goto kfree_exit;
	pcf2123_delay_trec();

	/* Finalize the initialization */
	rtc = rtc_device_register(pcf2123_driver.driver.name, &spi->dev,
	&pcf2123_rtc_ops, THIS_MODULE);

	if (IS_ERR(rtc)) {
	dev_err(&spi->dev, "failed to register.\n");
	ret = PTR_ERR(rtc);
	goto kfree_exit;
	}

	pdata->rtc = rtc;

	for (i = 0; i < 16; i++) {
	sprintf(pdata->regs[i].name, "%1x", i);
	pdata->regs[i].attr.attr.mode = S_IRUGO \| S_IWUSR;
	pdata->regs[i].attr.attr.name = pdata->regs[i].name;
	pdata->regs[i].attr.show = pcf2123_show;
	pdata->regs[i].attr.store = pcf2123_store;
	ret = device_create_file(&spi->dev, &pdata->regs[i].attr);
	if (ret) {
	dev_err(&spi->dev, "Unable to create sysfs %s\n",
	pdata->regs[i].name);
	goto sysfs_exit;
	}
	}

	return 0;

	sysfs_exit:
	for (i--; i >= 0; i--)
	device_remove_file(&spi->dev, &pdata->regs[i].attr);

	kfree_exit:
	kfree(pdata);
	spi->dev.platform_data = NULL;
	return ret;
	}

	static int __devexit pcf2123_remove(struct spi_device *spi)
	{
	struct pcf2123_plat_data *pdata = spi->dev.platform_data;
	int i;

	if (pdata) {
	struct rtc_device *rtc = pdata->rtc;

	if (rtc)
	rtc_device_unregister(rtc);
	for (i = 0; i < 16; i++)
	if (pdata->regs[i].name[0])
	device_remove_file(&spi->dev,
	&pdata->regs[i].attr);
	kfree(pdata);
	}

	return 0;
	}

	static struct spi_driver pcf2123_driver = {
	.driver = {
	.name = "rtc-pcf2123",
	.bus = &spi_bus_type,
	.owner = THIS_MODULE,
	},
	.probe = pcf2123_probe,
	.remove = __devexit_p(pcf2123_remove),
	};

	static int __init pcf2123_init(void)
	{
	return spi_register_driver(&pcf2123_driver);
	}

	static void __exit pcf2123_exit(void)
	{
	spi_unregister_driver(&pcf2123_driver);
	}

	MODULE_AUTHOR("Chris Verges <chrisv@cyberswitching.com>");
	MODULE_DESCRIPTION("NXP PCF2123 RTC driver");
	MODULE_LICENSE("GPL");
	MODULE_VERSION(DRV_VERSION);

	module_init(pcf2123_init);
	module_exit(pcf2123_exit);