drivers/rtc/rtc-v3020.c - kernel/msm-5.4 - Gitiles

 /* drivers/rtc/rtc-v3020.c
  *
  * Copyright (C) 2006 8D Technologies inc.
  * Copyright (C) 2004 Compulab Ltd.
  *
  * 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.
  *
  * Driver for the V3020 RTC
  *
  * Changelog:
  *
  *  10-May-2006: Raphael Assenat <raph@8d.com>
  *				- Converted to platform driver
  *				- Use the generic rtc class
  *
  *  ??-???-2004: Someone at Compulab
  *  			- Initial driver creation.
  *
  */
 #include <linux/platform_device.h>
 #include <linux/module.h>
 #include <linux/init.h>
 #include <linux/rtc.h>
 #include <linux/types.h>
 #include <linux/bcd.h>
 #include <linux/rtc-v3020.h>
 #include <linux/delay.h>
 #include <linux/gpio.h>

 #include <linux/io.h>

 #undef DEBUG

 struct v3020;

 struct v3020_chip_ops {
 	int (*map_io)(struct v3020 *chip, struct platform_device *pdev,
 		      struct v3020_platform_data *pdata);
 	void (*unmap_io)(struct v3020 *chip);
 	unsigned char (*read_bit)(struct v3020 *chip);
 	void (*write_bit)(struct v3020 *chip, unsigned char bit);
 };

 #define V3020_CS	0
 #define V3020_WR	1
 #define V3020_RD	2
 #define V3020_IO	3

 struct v3020_gpio {
 	const char *name;
 	unsigned int gpio;
 };

 struct v3020 {
 	/* MMIO access */
 	void __iomem *ioaddress;
 	int leftshift;

 	/* GPIO access */
 	struct v3020_gpio *gpio;

 	struct v3020_chip_ops *ops;

 	struct rtc_device *rtc;
 };


 static int v3020_mmio_map(struct v3020 *chip, struct platform_device *pdev,
 			  struct v3020_platform_data *pdata)
 {
 	if (pdev->num_resources != 1)
 		return -EBUSY;

 	if (pdev->resource[0].flags != IORESOURCE_MEM)
 		return -EBUSY;

 	chip->leftshift = pdata->leftshift;
 	chip->ioaddress = ioremap(pdev->resource[0].start, 1);
 	if (chip->ioaddress == NULL)
 		return -EBUSY;

 	return 0;
 }

 static void v3020_mmio_unmap(struct v3020 *chip)
 {
 	iounmap(chip->ioaddress);
 }

 static void v3020_mmio_write_bit(struct v3020 *chip, unsigned char bit)
 {
 	writel(bit << chip->leftshift, chip->ioaddress);
 }

 static unsigned char v3020_mmio_read_bit(struct v3020 *chip)
 {
 	return !!(readl(chip->ioaddress) & (1 << chip->leftshift));
 }

 static struct v3020_chip_ops v3020_mmio_ops = {
 	.map_io		= v3020_mmio_map,
 	.unmap_io	= v3020_mmio_unmap,
 	.read_bit	= v3020_mmio_read_bit,
 	.write_bit	= v3020_mmio_write_bit,
 };

 static struct v3020_gpio v3020_gpio[] = {
 	{ "RTC CS", 0 },
 	{ "RTC WR", 0 },
 	{ "RTC RD", 0 },
 	{ "RTC IO", 0 },
 };

 static int v3020_gpio_map(struct v3020 *chip, struct platform_device *pdev,
 			  struct v3020_platform_data *pdata)
 {
 	int i, err;

 	v3020_gpio[V3020_CS].gpio = pdata->gpio_cs;
 	v3020_gpio[V3020_WR].gpio = pdata->gpio_wr;
 	v3020_gpio[V3020_RD].gpio = pdata->gpio_rd;
 	v3020_gpio[V3020_IO].gpio = pdata->gpio_io;

 	for (i = 0; i < ARRAY_SIZE(v3020_gpio); i++) {
 		err = gpio_request(v3020_gpio[i].gpio, v3020_gpio[i].name);
 		if (err)
 			goto err_request;

 		gpio_direction_output(v3020_gpio[i].gpio, 1);
 	}

 	chip->gpio = v3020_gpio;

 	return 0;

 err_request:
 	while (--i >= 0)
 		gpio_free(v3020_gpio[i].gpio);

 	return err;
 }

 static void v3020_gpio_unmap(struct v3020 *chip)
 {
 	int i;

 	for (i = 0; i < ARRAY_SIZE(v3020_gpio); i++)
 		gpio_free(v3020_gpio[i].gpio);
 }

 static void v3020_gpio_write_bit(struct v3020 *chip, unsigned char bit)
 {
 	gpio_direction_output(chip->gpio[V3020_IO].gpio, bit);
 	gpio_set_value(chip->gpio[V3020_CS].gpio, 0);
 	gpio_set_value(chip->gpio[V3020_WR].gpio, 0);
 	udelay(1);
 	gpio_set_value(chip->gpio[V3020_WR].gpio, 1);
 	gpio_set_value(chip->gpio[V3020_CS].gpio, 1);
 }

 static unsigned char v3020_gpio_read_bit(struct v3020 *chip)
 {
 	int bit;

 	gpio_direction_input(chip->gpio[V3020_IO].gpio);
 	gpio_set_value(chip->gpio[V3020_CS].gpio, 0);
 	gpio_set_value(chip->gpio[V3020_RD].gpio, 0);
 	udelay(1);
 	bit = !!gpio_get_value(chip->gpio[V3020_IO].gpio);
 	udelay(1);
 	gpio_set_value(chip->gpio[V3020_RD].gpio, 1);
 	gpio_set_value(chip->gpio[V3020_CS].gpio, 1);

 	return bit;
 }

 static struct v3020_chip_ops v3020_gpio_ops = {
 	.map_io		= v3020_gpio_map,
 	.unmap_io	= v3020_gpio_unmap,
 	.read_bit	= v3020_gpio_read_bit,
 	.write_bit	= v3020_gpio_write_bit,
 };

 static void v3020_set_reg(struct v3020 *chip, unsigned char address,
 			unsigned char data)
 {
 	int i;
 	unsigned char tmp;

 	tmp = address;
 	for (i = 0; i < 4; i++) {
 		chip->ops->write_bit(chip, (tmp & 1));
 		tmp >>= 1;
 		udelay(1);
 	}

 	/* Commands dont have data */
 	if (!V3020_IS_COMMAND(address)) {
 		for (i = 0; i < 8; i++) {
 			chip->ops->write_bit(chip, (data & 1));
 			data >>= 1;
 			udelay(1);
 		}
 	}
 }

 static unsigned char v3020_get_reg(struct v3020 *chip, unsigned char address)
 {
 	unsigned int data = 0;
 	int i;

 	for (i = 0; i < 4; i++) {
 		chip->ops->write_bit(chip, (address & 1));
 		address >>= 1;
 		udelay(1);
 	}

 	for (i = 0; i < 8; i++) {
 		data >>= 1;
 		if (chip->ops->read_bit(chip))
 			data |= 0x80;
 		udelay(1);
 	}

 	return data;
 }

 static int v3020_read_time(struct device *dev, struct rtc_time *dt)
 {
 	struct v3020 *chip = dev_get_drvdata(dev);
 	int tmp;

 	/* Copy the current time to ram... */
 	v3020_set_reg(chip, V3020_CMD_CLOCK2RAM, 0);

 	/* ...and then read constant values. */
 	tmp = v3020_get_reg(chip, V3020_SECONDS);
 	dt->tm_sec	= bcd2bin(tmp);
 	tmp = v3020_get_reg(chip, V3020_MINUTES);
 	dt->tm_min	= bcd2bin(tmp);
 	tmp = v3020_get_reg(chip, V3020_HOURS);
 	dt->tm_hour	= bcd2bin(tmp);
 	tmp = v3020_get_reg(chip, V3020_MONTH_DAY);
 	dt->tm_mday	= bcd2bin(tmp);
 	tmp = v3020_get_reg(chip, V3020_MONTH);
 	dt->tm_mon    = bcd2bin(tmp) - 1;
 	tmp = v3020_get_reg(chip, V3020_WEEK_DAY);
 	dt->tm_wday	= bcd2bin(tmp);
 	tmp = v3020_get_reg(chip, V3020_YEAR);
 	dt->tm_year = bcd2bin(tmp)+100;

 	dev_dbg(dev, "\n%s : Read RTC values\n", __func__);
 	dev_dbg(dev, "tm_hour: %i\n", dt->tm_hour);
 	dev_dbg(dev, "tm_min : %i\n", dt->tm_min);
 	dev_dbg(dev, "tm_sec : %i\n", dt->tm_sec);
 	dev_dbg(dev, "tm_year: %i\n", dt->tm_year);
 	dev_dbg(dev, "tm_mon : %i\n", dt->tm_mon);
 	dev_dbg(dev, "tm_mday: %i\n", dt->tm_mday);
 	dev_dbg(dev, "tm_wday: %i\n", dt->tm_wday);

 	return 0;
 }


 static int v3020_set_time(struct device *dev, struct rtc_time *dt)
 {
 	struct v3020 *chip = dev_get_drvdata(dev);

 	dev_dbg(dev, "\n%s : Setting RTC values\n", __func__);
 	dev_dbg(dev, "tm_sec : %i\n", dt->tm_sec);
 	dev_dbg(dev, "tm_min : %i\n", dt->tm_min);
 	dev_dbg(dev, "tm_hour: %i\n", dt->tm_hour);
 	dev_dbg(dev, "tm_mday: %i\n", dt->tm_mday);
 	dev_dbg(dev, "tm_wday: %i\n", dt->tm_wday);
 	dev_dbg(dev, "tm_year: %i\n", dt->tm_year);

 	/* Write all the values to ram... */
 	v3020_set_reg(chip, V3020_SECONDS, 	bin2bcd(dt->tm_sec));
 	v3020_set_reg(chip, V3020_MINUTES, 	bin2bcd(dt->tm_min));
 	v3020_set_reg(chip, V3020_HOURS, 	bin2bcd(dt->tm_hour));
 	v3020_set_reg(chip, V3020_MONTH_DAY,	bin2bcd(dt->tm_mday));
 	v3020_set_reg(chip, V3020_MONTH,     bin2bcd(dt->tm_mon + 1));
 	v3020_set_reg(chip, V3020_WEEK_DAY, 	bin2bcd(dt->tm_wday));
 	v3020_set_reg(chip, V3020_YEAR, 	bin2bcd(dt->tm_year % 100));

 	/* ...and set the clock. */
 	v3020_set_reg(chip, V3020_CMD_RAM2CLOCK, 0);

 	/* Compulab used this delay here. I dont know why,
 	 * the datasheet does not specify a delay. */
 	/*mdelay(5);*/

 	return 0;
 }

 static const struct rtc_class_ops v3020_rtc_ops = {
 	.read_time	= v3020_read_time,
 	.set_time	= v3020_set_time,
 };

 static int rtc_probe(struct platform_device *pdev)
 {
 	struct v3020_platform_data *pdata = pdev->dev.platform_data;
 	struct v3020 *chip;
 	int retval = -EBUSY;
 	int i;
 	int temp;

 	chip = kzalloc(sizeof *chip, GFP_KERNEL);
 	if (!chip)
 		return -ENOMEM;

 	if (pdata->use_gpio)
 		chip->ops = &v3020_gpio_ops;
 	else
 		chip->ops = &v3020_mmio_ops;

 	retval = chip->ops->map_io(chip, pdev, pdata);
 	if (retval)
 		goto err_chip;

 	/* Make sure the v3020 expects a communication cycle
 	 * by reading 8 times */
 	for (i = 0; i < 8; i++)
 		temp = chip->ops->read_bit(chip);

 	/* Test chip by doing a write/read sequence
 	 * to the chip ram */
 	v3020_set_reg(chip, V3020_SECONDS, 0x33);
 	if (v3020_get_reg(chip, V3020_SECONDS) != 0x33) {
 		retval = -ENODEV;
 		goto err_io;
 	}

 	/* Make sure frequency measurement mode, test modes, and lock
 	 * are all disabled */
 	v3020_set_reg(chip, V3020_STATUS_0, 0x0);

 	if (pdata->use_gpio)
 		dev_info(&pdev->dev, "Chip available at GPIOs "
 			 "%d, %d, %d, %d\n",
 			 chip->gpio[V3020_CS].gpio, chip->gpio[V3020_WR].gpio,
 			 chip->gpio[V3020_RD].gpio, chip->gpio[V3020_IO].gpio);
 	else
 		dev_info(&pdev->dev, "Chip available at "
 			 "physical address 0x%llx,"
 			 "data connected to D%d\n",
 			 (unsigned long long)pdev->resource[0].start,
 			 chip->leftshift);

 	platform_set_drvdata(pdev, chip);

 	chip->rtc = rtc_device_register("v3020",
 				&pdev->dev, &v3020_rtc_ops, THIS_MODULE);
 	if (IS_ERR(chip->rtc)) {
 		retval = PTR_ERR(chip->rtc);
 		goto err_io;
 	}

 	return 0;

 err_io:
 	chip->ops->unmap_io(chip);
 err_chip:
 	kfree(chip);

 	return retval;
 }

 static int rtc_remove(struct platform_device *dev)
 {
 	struct v3020 *chip = platform_get_drvdata(dev);
 	struct rtc_device *rtc = chip->rtc;

 	if (rtc)
 		rtc_device_unregister(rtc);

 	chip->ops->unmap_io(chip);
 	kfree(chip);

 	return 0;
 }

 static struct platform_driver rtc_device_driver = {
 	.probe	= rtc_probe,
 	.remove = rtc_remove,
 	.driver = {
 		.name	= "v3020",
 		.owner	= THIS_MODULE,
 	},
 };

 static __init int v3020_init(void)
 {
 	return platform_driver_register(&rtc_device_driver);
 }

 static __exit void v3020_exit(void)
 {
 	platform_driver_unregister(&rtc_device_driver);
 }

 module_init(v3020_init);
 module_exit(v3020_exit);

 MODULE_DESCRIPTION("V3020 RTC");
 MODULE_AUTHOR("Raphael Assenat");
 MODULE_LICENSE("GPL");
 MODULE_ALIAS("platform:v3020");
	/* drivers/rtc/rtc-v3020.c
	*
	* Copyright (C) 2006 8D Technologies inc.
	* Copyright (C) 2004 Compulab Ltd.
	*
	* 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.
	*
	* Driver for the V3020 RTC
	*
	* Changelog:
	*
	* 10-May-2006: Raphael Assenat <raph@8d.com>
	* - Converted to platform driver
	* - Use the generic rtc class
	*
	* ??-???-2004: Someone at Compulab
	* - Initial driver creation.
	*
	*/
	#include <linux/platform_device.h>
	#include <linux/module.h>
	#include <linux/init.h>
	#include <linux/rtc.h>
	#include <linux/types.h>
	#include <linux/bcd.h>
	#include <linux/rtc-v3020.h>
	#include <linux/delay.h>
	#include <linux/gpio.h>

	#include <linux/io.h>

	#undef DEBUG

	struct v3020;

	struct v3020_chip_ops {
	int (map_io)(struct v3020 chip, struct platform_device *pdev,
	struct v3020_platform_data *pdata);
	void (unmap_io)(struct v3020 chip);
	unsigned char (read_bit)(struct v3020 chip);
	void (write_bit)(struct v3020 chip, unsigned char bit);
	};

	#define V3020_CS 0
	#define V3020_WR 1
	#define V3020_RD 2
	#define V3020_IO 3

	struct v3020_gpio {
	const char *name;
	unsigned int gpio;
	};

	struct v3020 {
	/* MMIO access */
	void __iomem *ioaddress;
	int leftshift;

	/* GPIO access */
	struct v3020_gpio *gpio;

	struct v3020_chip_ops *ops;

	struct rtc_device *rtc;
	};


	static int v3020_mmio_map(struct v3020 chip, struct platform_device pdev,
	struct v3020_platform_data *pdata)
	{
	if (pdev->num_resources != 1)
	return -EBUSY;

	if (pdev->resource[0].flags != IORESOURCE_MEM)
	return -EBUSY;

	chip->leftshift = pdata->leftshift;
	chip->ioaddress = ioremap(pdev->resource[0].start, 1);
	if (chip->ioaddress == NULL)
	return -EBUSY;

	return 0;
	}

	static void v3020_mmio_unmap(struct v3020 *chip)
	{
	iounmap(chip->ioaddress);
	}

	static void v3020_mmio_write_bit(struct v3020 *chip, unsigned char bit)
	{
	writel(bit << chip->leftshift, chip->ioaddress);
	}

	static unsigned char v3020_mmio_read_bit(struct v3020 *chip)
	{
	return !!(readl(chip->ioaddress) & (1 << chip->leftshift));
	}

	static struct v3020_chip_ops v3020_mmio_ops = {
	.map_io = v3020_mmio_map,
	.unmap_io = v3020_mmio_unmap,
	.read_bit = v3020_mmio_read_bit,
	.write_bit = v3020_mmio_write_bit,
	};

	static struct v3020_gpio v3020_gpio[] = {
	{ "RTC CS", 0 },
	{ "RTC WR", 0 },
	{ "RTC RD", 0 },
	{ "RTC IO", 0 },
	};

	static int v3020_gpio_map(struct v3020 chip, struct platform_device pdev,
	struct v3020_platform_data *pdata)
	{
	int i, err;

	v3020_gpio[V3020_CS].gpio = pdata->gpio_cs;
	v3020_gpio[V3020_WR].gpio = pdata->gpio_wr;
	v3020_gpio[V3020_RD].gpio = pdata->gpio_rd;
	v3020_gpio[V3020_IO].gpio = pdata->gpio_io;

	for (i = 0; i < ARRAY_SIZE(v3020_gpio); i++) {
	err = gpio_request(v3020_gpio[i].gpio, v3020_gpio[i].name);
	if (err)
	goto err_request;

	gpio_direction_output(v3020_gpio[i].gpio, 1);
	}

	chip->gpio = v3020_gpio;

	return 0;

	err_request:
	while (--i >= 0)
	gpio_free(v3020_gpio[i].gpio);

	return err;
	}

	static void v3020_gpio_unmap(struct v3020 *chip)
	{
	int i;

	for (i = 0; i < ARRAY_SIZE(v3020_gpio); i++)
	gpio_free(v3020_gpio[i].gpio);
	}

	static void v3020_gpio_write_bit(struct v3020 *chip, unsigned char bit)
	{
	gpio_direction_output(chip->gpio[V3020_IO].gpio, bit);
	gpio_set_value(chip->gpio[V3020_CS].gpio, 0);
	gpio_set_value(chip->gpio[V3020_WR].gpio, 0);
	udelay(1);
	gpio_set_value(chip->gpio[V3020_WR].gpio, 1);
	gpio_set_value(chip->gpio[V3020_CS].gpio, 1);
	}

	static unsigned char v3020_gpio_read_bit(struct v3020 *chip)
	{
	int bit;

	gpio_direction_input(chip->gpio[V3020_IO].gpio);
	gpio_set_value(chip->gpio[V3020_CS].gpio, 0);
	gpio_set_value(chip->gpio[V3020_RD].gpio, 0);
	udelay(1);
	bit = !!gpio_get_value(chip->gpio[V3020_IO].gpio);
	udelay(1);
	gpio_set_value(chip->gpio[V3020_RD].gpio, 1);
	gpio_set_value(chip->gpio[V3020_CS].gpio, 1);

	return bit;
	}

	static struct v3020_chip_ops v3020_gpio_ops = {
	.map_io = v3020_gpio_map,
	.unmap_io = v3020_gpio_unmap,
	.read_bit = v3020_gpio_read_bit,
	.write_bit = v3020_gpio_write_bit,
	};

	static void v3020_set_reg(struct v3020 *chip, unsigned char address,
	unsigned char data)
	{
	int i;
	unsigned char tmp;

	tmp = address;
	for (i = 0; i < 4; i++) {
	chip->ops->write_bit(chip, (tmp & 1));
	tmp >>= 1;
	udelay(1);
	}

	/* Commands dont have data */
	if (!V3020_IS_COMMAND(address)) {
	for (i = 0; i < 8; i++) {
	chip->ops->write_bit(chip, (data & 1));
	data >>= 1;
	udelay(1);
	}
	}
	}

	static unsigned char v3020_get_reg(struct v3020 *chip, unsigned char address)
	{
	unsigned int data = 0;
	int i;

	for (i = 0; i < 4; i++) {
	chip->ops->write_bit(chip, (address & 1));
	address >>= 1;
	udelay(1);
	}

	for (i = 0; i < 8; i++) {
	data >>= 1;
	if (chip->ops->read_bit(chip))
	data \|= 0x80;
	udelay(1);
	}

	return data;
	}

	static int v3020_read_time(struct device dev, struct rtc_time dt)
	{
	struct v3020 *chip = dev_get_drvdata(dev);
	int tmp;

	/* Copy the current time to ram... */
	v3020_set_reg(chip, V3020_CMD_CLOCK2RAM, 0);

	/* ...and then read constant values. */
	tmp = v3020_get_reg(chip, V3020_SECONDS);
	dt->tm_sec = bcd2bin(tmp);
	tmp = v3020_get_reg(chip, V3020_MINUTES);
	dt->tm_min = bcd2bin(tmp);
	tmp = v3020_get_reg(chip, V3020_HOURS);
	dt->tm_hour = bcd2bin(tmp);
	tmp = v3020_get_reg(chip, V3020_MONTH_DAY);
	dt->tm_mday = bcd2bin(tmp);
	tmp = v3020_get_reg(chip, V3020_MONTH);
	dt->tm_mon = bcd2bin(tmp) - 1;
	tmp = v3020_get_reg(chip, V3020_WEEK_DAY);
	dt->tm_wday = bcd2bin(tmp);
	tmp = v3020_get_reg(chip, V3020_YEAR);
	dt->tm_year = bcd2bin(tmp)+100;

	dev_dbg(dev, "\n%s : Read RTC values\n", __func__);
	dev_dbg(dev, "tm_hour: %i\n", dt->tm_hour);
	dev_dbg(dev, "tm_min : %i\n", dt->tm_min);
	dev_dbg(dev, "tm_sec : %i\n", dt->tm_sec);
	dev_dbg(dev, "tm_year: %i\n", dt->tm_year);
	dev_dbg(dev, "tm_mon : %i\n", dt->tm_mon);
	dev_dbg(dev, "tm_mday: %i\n", dt->tm_mday);
	dev_dbg(dev, "tm_wday: %i\n", dt->tm_wday);

	return 0;
	}


	static int v3020_set_time(struct device dev, struct rtc_time dt)
	{
	struct v3020 *chip = dev_get_drvdata(dev);

	dev_dbg(dev, "\n%s : Setting RTC values\n", __func__);
	dev_dbg(dev, "tm_sec : %i\n", dt->tm_sec);
	dev_dbg(dev, "tm_min : %i\n", dt->tm_min);
	dev_dbg(dev, "tm_hour: %i\n", dt->tm_hour);
	dev_dbg(dev, "tm_mday: %i\n", dt->tm_mday);
	dev_dbg(dev, "tm_wday: %i\n", dt->tm_wday);
	dev_dbg(dev, "tm_year: %i\n", dt->tm_year);

	/* Write all the values to ram... */
	v3020_set_reg(chip, V3020_SECONDS, bin2bcd(dt->tm_sec));
	v3020_set_reg(chip, V3020_MINUTES, bin2bcd(dt->tm_min));
	v3020_set_reg(chip, V3020_HOURS, bin2bcd(dt->tm_hour));
	v3020_set_reg(chip, V3020_MONTH_DAY, bin2bcd(dt->tm_mday));
	v3020_set_reg(chip, V3020_MONTH, bin2bcd(dt->tm_mon + 1));
	v3020_set_reg(chip, V3020_WEEK_DAY, bin2bcd(dt->tm_wday));
	v3020_set_reg(chip, V3020_YEAR, bin2bcd(dt->tm_year % 100));

	/* ...and set the clock. */
	v3020_set_reg(chip, V3020_CMD_RAM2CLOCK, 0);

	/* Compulab used this delay here. I dont know why,
	* the datasheet does not specify a delay. */
	/mdelay(5);/

	return 0;
	}

	static const struct rtc_class_ops v3020_rtc_ops = {
	.read_time = v3020_read_time,
	.set_time = v3020_set_time,
	};

	static int rtc_probe(struct platform_device *pdev)
	{
	struct v3020_platform_data *pdata = pdev->dev.platform_data;
	struct v3020 *chip;
	int retval = -EBUSY;
	int i;
	int temp;

	chip = kzalloc(sizeof *chip, GFP_KERNEL);
	if (!chip)
	return -ENOMEM;

	if (pdata->use_gpio)
	chip->ops = &v3020_gpio_ops;
	else
	chip->ops = &v3020_mmio_ops;

	retval = chip->ops->map_io(chip, pdev, pdata);
	if (retval)
	goto err_chip;

	/* Make sure the v3020 expects a communication cycle
	* by reading 8 times */
	for (i = 0; i < 8; i++)
	temp = chip->ops->read_bit(chip);

	/* Test chip by doing a write/read sequence
	* to the chip ram */
	v3020_set_reg(chip, V3020_SECONDS, 0x33);
	if (v3020_get_reg(chip, V3020_SECONDS) != 0x33) {
	retval = -ENODEV;
	goto err_io;
	}

	/* Make sure frequency measurement mode, test modes, and lock
	* are all disabled */
	v3020_set_reg(chip, V3020_STATUS_0, 0x0);

	if (pdata->use_gpio)
	dev_info(&pdev->dev, "Chip available at GPIOs "
	"%d, %d, %d, %d\n",
	chip->gpio[V3020_CS].gpio, chip->gpio[V3020_WR].gpio,
	chip->gpio[V3020_RD].gpio, chip->gpio[V3020_IO].gpio);
	else
	dev_info(&pdev->dev, "Chip available at "
	"physical address 0x%llx,"
	"data connected to D%d\n",
	(unsigned long long)pdev->resource[0].start,
	chip->leftshift);

	platform_set_drvdata(pdev, chip);

	chip->rtc = rtc_device_register("v3020",
	&pdev->dev, &v3020_rtc_ops, THIS_MODULE);
	if (IS_ERR(chip->rtc)) {
	retval = PTR_ERR(chip->rtc);
	goto err_io;
	}

	return 0;

	err_io:
	chip->ops->unmap_io(chip);
	err_chip:
	kfree(chip);

	return retval;
	}

	static int rtc_remove(struct platform_device *dev)
	{
	struct v3020 *chip = platform_get_drvdata(dev);
	struct rtc_device *rtc = chip->rtc;

	if (rtc)
	rtc_device_unregister(rtc);

	chip->ops->unmap_io(chip);
	kfree(chip);

	return 0;
	}

	static struct platform_driver rtc_device_driver = {
	.probe = rtc_probe,
	.remove = rtc_remove,
	.driver = {
	.name = "v3020",
	.owner = THIS_MODULE,
	},
	};

	static __init int v3020_init(void)
	{
	return platform_driver_register(&rtc_device_driver);
	}

	static __exit void v3020_exit(void)
	{
	platform_driver_unregister(&rtc_device_driver);
	}

	module_init(v3020_init);
	module_exit(v3020_exit);

	MODULE_DESCRIPTION("V3020 RTC");
	MODULE_AUTHOR("Raphael Assenat");
	MODULE_LICENSE("GPL");
	MODULE_ALIAS("platform:v3020");