rtc: add support for maxim dallas ds1682

This is a patch to add support for
maxim dallas ds1682 total elapsed time recorder

Signed‐off‐by: Venkat Prashanth B U <venkat.prashanth2498@gmail.com>
---
---
 drivers/rtc/Kconfig      |   9 ++
 drivers/rtc/Makefile     |   1 +
 drivers/rtc/rtc-ds1682.c | 288 +++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 298 insertions(+)

Hi,

Please run checkpatch --strict before submitting.

Also, it seems to me this is a regular i2c chip, I don't think the whole
bitbanging is necessary.

On 24/12/2016 at 08:47:14 -0800, Venkat Prashanth B U wrote:
> This is a patch to add support for
> maxim dallas ds1682 total elapsed time recorder
> 
> Signed‐off‐by: Venkat Prashanth B U <venkat.prashanth2498@gmail.com>
> ---
> ---
>  drivers/rtc/Kconfig      |   9 ++
>  drivers/rtc/Makefile     |   1 +
>  drivers/rtc/rtc-ds1682.c | 288 +++++++++++++++++++++++++++++++++++++++++++
>  3 files changed, 298 insertions(+)
> 
> diff --git a/drivers/rtc/Kconfig b/drivers/rtc/Kconfig
> index e859d14..bcab91f 100644
> --- a/drivers/rtc/Kconfig
> +++ b/drivers/rtc/Kconfig
> @@ -275,6 +275,15 @@ config RTC_DRV_DS1672
>  	  This driver can also be built as a module. If so, the module
>  	  will be called rtc-ds1672.
>  
> +config RTC_DRV_DS1682
> +	tristate "Dallas/Maxim DS1682"
> +	help
> +	  If you say yes here you get support for the
> +	  Dallas/Maxim DS1682 total elapsed time recorder.
> +
> +	  This driver can also be built as a module. If so, the module
> +	  will be called rtc-ds1682.
> +
>  config RTC_DRV_HYM8563
>  	tristate "Haoyu Microelectronics HYM8563"
>  	depends on OF
> diff --git a/drivers/rtc/Makefile b/drivers/rtc/Makefile
> index 1ac694a..70bb28c 100644
> --- a/drivers/rtc/Makefile
> +++ b/drivers/rtc/Makefile
> @@ -58,6 +58,7 @@ obj-$(CONFIG_RTC_DRV_DS1390)	+= rtc-ds1390.o
>  obj-$(CONFIG_RTC_DRV_DS1511)	+= rtc-ds1511.o
>  obj-$(CONFIG_RTC_DRV_DS1553)	+= rtc-ds1553.o
>  obj-$(CONFIG_RTC_DRV_DS1672)	+= rtc-ds1672.o
> +obj-$(CONFIG_RTC_DRV_DS1682)	+= rtc-ds1682.o
>  obj-$(CONFIG_RTC_DRV_DS1685_FAMILY)	+= rtc-ds1685.o
>  obj-$(CONFIG_RTC_DRV_DS1742)	+= rtc-ds1742.o
>  obj-$(CONFIG_RTC_DRV_DS2404)	+= rtc-ds2404.o
> diff --git a/drivers/rtc/rtc-ds1682.c b/drivers/rtc/rtc-ds1682.c
> index e69de29..fad440e 100644
> --- a/drivers/rtc/rtc-ds1682.c
> +++ b/drivers/rtc/rtc-ds1682.c
> @@ -0,0 +1,288 @@
> +/* Driver for Dallas Semiconductor DS1682 2 wire total elapsed
> + * time recorder
> + *
> + * Author : Venkat Prashanth B U <venkat.prashanth2498@gmail.com>
> + *
> + * 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/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/delay.h>
> +#include <linux/gpio.h>
> +#include <linux/slab.h>
> +
> +#include <linux/io.h>
> +
> +#define DS1682_READ_MEMORY_CMD 0x1D
> +
> +#ifndef __LINUX_DS1682_H
> +#define __LINUX_DS1682_H
> +
> +const struct ds1682_platform_data {
> +
> +
> +	unsigned int gpio_rst;
> +	unsigned int gpio_clk;
> +	unsigned int gpio_dq;
> +};
> +#endif
> +
> +const struct ds1682;
> +
> +const struct ds1682_chip_ops {
> +	int (*map_io)(const struct ds1682 *chip, struct platform_device *pdev,
> +		  const struct ds1682_platform_data *pdata);
> +	void (*unmap_io)(const struct ds1682 *chip);
> +};
> +
> +#define DS1682_RST	0
> +#define DS1682_CLK	1
> +#define DS1682_DQ	2
> +
> +const struct ds1682_gpio {
> +	const char *name;
> +	unsigned int gpio;
> +};
> +
> +const struct ds1682 {
> +	const struct ds1682_gpio *gpio;
> +	const struct ds1682_chip_ops *ops;
> +	const struct rtc_device *rtc;
> +};
> +
> +const struct ds1682_gpio ds1682_gpio[] = {
> +	{ "RTC RST", 0 },
> +	{ "RTC CLK", 0 },
> +	{ "RTC DQ", 0 },
> +};
> +
> +int ds1682_gpio_map(const struct ds1682 *chip, struct platform_device *pdev,
> +			  const struct ds1682_platform_data *pdata)
> +{
> +	int i, err;
> +
> +	ds1682_gpio[DS1682_RST].gpio = pdata->gpio_rst;
> +	ds1682_gpio[DS1682_CLK].gpio = pdata->gpio_clk;
> +	ds1682_gpio[DS1682_DQ].gpio = pdata->gpio_dq;
> +
> +	for (i = 0; i < ARRAY_SIZE(ds1682_gpio); i++) {
> +		err = gpio_request(ds1682_gpio[i].gpio, ds1682_gpio[i].name);
> +		if (err) {
> +			dev_err(&pdev->dev, "error mapping gpio %s: %d\n",
> +				ds1682_gpio[i].name, err);
> +			goto err_request;
> +		}
> +		if (i != DS1682_DQ)
> +			gpio_direction_output(ds1682_gpio[i].gpio, 1);
> +	}
> +
> +	chip->gpio = ds1682_gpio;
> +	return 0;
> +
> +err_request:
> +	while (--i >= 0)
> +		gpio_free(ds1682_gpio[i].gpio);
> +	return err;
> +}
> +
> +static void ds1682_gpio_unmap(const struct ds1682 *chip)
> +{
> +	int i;
> +
> +	for (i = 0; i < ARRAY_SIZE(ds1682_gpio); i++)
> +		gpio_free(ds1682_gpio[i].gpio);
> +}
> +
> +static const struct ds1682_chip_ops ds1682_gpio_ops = {
> +	.map_io		= ds1682_gpio_map,
> +	.unmap_io	= ds1682_gpio_unmap,
> +};
> +
> +static void ds1682_reset(const struct device *dev)
> +{
> +	gpio_set_value(ds1682_gpio[DS1682_RST].gpio, 0);
> +	udelay(1000);
> +	gpio_set_value(ds1682_gpio[DS1682_RST].gpio, 1);
> +	gpio_set_value(ds1682_gpio[DS1682_CLK].gpio, 0);
> +	gpio_direction_output(ds1682_gpio[DS1682_DQ].gpio, 0);
> +	udelay(10);
> +}
> +
> +static void ds1682_write_byte(const struct device *dev, u8 byte)
> +{
> +	int i;
> +
> +	gpio_direction_output(ds1682_gpio[DS1682_DQ].gpio, 1);
> +	for (i = 0; i < 8; i++) {
> +		gpio_set_value(ds1682_gpio[DS1682_DQ].gpio, byte & (1 << i));
> +		udelay(10);
> +		gpio_set_value(ds1682_gpio[DS1682_CLK].gpio, 1);
> +		udelay(10);
> +		gpio_set_value(ds1682_gpio[DS1682_CLK].gpio, 0);
> +		udelay(10);
> +	}
> +}
> +
> +static u8 ds1682_read_byte(const struct device *dev)
> +{
> +	int i;
> +	u8 ret = 0;
> +
> +	gpio_direction_input(ds1682_gpio[DS1682_DQ].gpio);
> +
> +	for (i = 0; i < 8; i++) {
> +		gpio_set_value(ds1682_gpio[DS1682_CLK].gpio, 0);
> +		udelay(10);
> +		if (gpio_get_value(ds1682_gpio[DS1682_DQ].gpio))
> +			ret |= 1 << i;
> +		gpio_set_value(ds1682_gpio[DS1682_CLK].gpio, 1);
> +		udelay(10);
> +	}
> +	return ret;
> +}
> +
> +static void ds1682_read_memory(const struct device *dev, u16 offset,
> +			       int length, u8 *out)
> +{
> +	ds1682_reset(dev);
> +	ds1682_write_byte(dev, DS1682_READ_MEMORY_CMD);
> +	ds1682_write_byte(dev, offset & 0xff);
> +	ds1682_write_byte(dev, (offset >> 8) & 0xff);
> +	while (length--)
> +		*out++ = ds1682_read_byte(dev);
> +}
> +
> +static void ds1682_write_memory(const struct device *dev, u16 offset,
> +				int length, u8 *out)
> +{
> +	int i;
> +	u8 ta01, ta02, es;
> +
> +	ds1682_reset(dev);
> +	ds1682_write_byte(dev, offset & 0xff);
> +	ds1682_write_byte(dev, (offset >> 8) & 0xff);
> +
> +	for (i = 0; i < length; i++)
> +		ds1682_write_byte(dev, out[i]);
> +
> +	ds1682_reset(dev);
> +
> +	ta01 = ds1682_read_byte(dev);
> +	ta02 = ds1682_read_byte(dev);
> +	es = ds1682_read_byte(dev);
> +
> +	for (i = 0; i < length; i++) {
> +		if (out[i] != ds1682_read_byte(dev)) {
> +			dev_err(dev, "read invalid data\n");
> +			return;
> +		}
> +	}
> +
> +	ds1682_reset(dev);
> +	ds1682_write_byte(dev, ta01);
> +	ds1682_write_byte(dev, ta02);
> +	ds1682_write_byte(dev, es);
> +	gpio_direction_input(ds1682_gpio[DS1682_DQ].gpio);
> +	while (gpio_get_value(ds1682_gpio[DS1682_DQ].gpio))
> +	;
> +}
> +
> +static void ds1682_enable_osc(const struct device *dev)
> +{
> +	u8 in[1] = { 0x10 }; /* enable oscillator */
> +
> +	ds1682_write_memory(dev, 0x201, 1, in);
> +}
> +
> +static int ds1682_read_time(const struct device *dev, struct rtc_time *dt)
> +{
> +	unsigned long time = 0;
> +
> +	ds1682_read_memory(dev, 0x203, 4, (u8 *)&time);
> +	time = le32_to_cpu(time);
> +	rtc_time_to_tm(time, dt);
> +	return rtc_valid_tm(dt);
> +}
> +
> +static int ds1682_set_mmss(const struct device *dev, unsigned long secs)
> +{
> +	u32 time = cpu_to_le32(secs);
> +
> +	ds1682_write_memory(dev, 0x203, 4, (u8 *)&time);
> +	return 0;
> +}
> +
> +static const struct rtc_class_ops ds1682_rtc_ops = {
> +	.read_time	= ds1682_read_time,
> +	.set_mmss	= ds1682_set_mmss,
> +};
> +
> +static int rtc_probe(const struct platform_device *pdev)
> +{
> +const struct ds1682_platform_data *pdata = dev_get_platdata(&pdev->dev);
> +	const struct ds1682 *chip;
> +	int retval = -EBUSY;
> +
> +chip = devm_kzalloc(&pdev->dev, sizeof(const struct ds1682), GFP_KERNEL);
> +	if (!chip)
> +		return -ENOMEM;
> +
> +	chip->ops = &ds1682_gpio_ops;
> +
> +	retval = chip->ops->map_io(chip, pdev, pdata);
> +	if (retval)
> +		goto err_chip;
> +
> +	dev_info(&pdev->dev, "using GPIOs RST:%d, CLK:%d, DQ:%d\n",
> +		 chip->gpio[DS1682_RST].gpio, chip->gpio[DS1682_CLK].gpio,
> +		 chip->gpio[DS1682_DQ].gpio);
> +
> +	platform_set_drvdata(pdev, chip);
> +
> +	chip->rtc = devm_rtc_device_register(&pdev->dev, "ds1682",
> +					&ds1682_rtc_ops, THIS_MODULE);
> +	if (IS_ERR(chip->rtc)) {
> +		retval = PTR_ERR(chip->rtc);
> +		goto err_io;
> +	}
> +
> +	ds1682_enable_osc(&pdev->dev);
> +	return 0;
> +
> +err_io:
> +	chip->ops->unmap_io(chip);
> +err_chip:
> +	return retval;
> +}
> +
> +static int rtc_remove(const struct platform_device *dev)
> +{
> +const struct ds1682 *chip = platform_get_drvdata(dev);
> +
> +	chip->ops->unmap_io(chip);
> +
> +	return 0;
> +}
> +
> +const struct platform_driver rtc_device_driver = {
> +	.probe	= rtc_probe,
> +	.remove = rtc_remove,
> +	.driver = {
> +		.name	= "ds1682",
> +	},
> +};
> +module_platform_driver(rtc_device_driver);
> +
> +MODULE_DESCRIPTION("DS1682 Total Elapsed Time Recorder");
> +MODULE_AUTHOR("Venkat Prashanth B U <venkat.prashanth2498@gmail.com>");
> +MODULE_LICENSE("GPL");
> +MODULE_ALIAS("platform:ds1682");
> +
> -- 
> 1.9.2
>