Re: [PATCH] rtc: add support for maxim dallas rtc ds1347

[Alessandro Zummo]

On Thu, 20 Mar 2014 21:55:33 +0530
RAGHAVENDRA GANIGA <ravi23ganiga@xxxxxxxxx> wrote:

 Thanks for your submission!
 just a few comments below:

> ---
>  drivers/rtc/Kconfig      |   12 ++++
>  drivers/rtc/Makefile     |    1 +
>  drivers/rtc/rtc-ds1347.c |  175 ++++++++++++++++++++++++++++++++++++++++++++++
>  3 files changed, 188 insertions(+)
>  create mode 100644 drivers/rtc/rtc-ds1347.c
> 
> diff --git a/drivers/rtc/Kconfig b/drivers/rtc/Kconfig
> index db933de..2e565f8 100644
> --- a/drivers/rtc/Kconfig
> +++ b/drivers/rtc/Kconfig
> @@ -573,6 +573,18 @@ config RTC_DRV_DS1305
>  	  This driver can also be built as a module. If so, the module
>  	  will be called rtc-ds1305.
>  
> +config RTC_DRV_DS1347
> +	tristate "Dallas/Maxim DS1347"
> +	help
> +	  If you say yes here you get support for the
> +	  Dallas/Maxim DS1347 chips.
> +
> +	  This driver only supports the RTC feature, and not other chip
> +	  features such as alarms.
> +
> +	  This driver can also be built as a module. If so, the module
> +	  will be called rtc-ds1347.
> +
>  config RTC_DRV_DS1390
>  	tristate "Dallas/Maxim DS1390/93/94"
>  	help
> diff --git a/drivers/rtc/Makefile b/drivers/rtc/Makefile
> index b427bf7..40a0991 100644
> --- a/drivers/rtc/Makefile
> +++ b/drivers/rtc/Makefile
> @@ -40,6 +40,7 @@ obj-$(CONFIG_RTC_DRV_DS1286)	+= rtc-ds1286.o
>  obj-$(CONFIG_RTC_DRV_DS1302)	+= rtc-ds1302.o
>  obj-$(CONFIG_RTC_DRV_DS1305)	+= rtc-ds1305.o
>  obj-$(CONFIG_RTC_DRV_DS1307)	+= rtc-ds1307.o
> +obj-$(CONFIG_RTC_DRV_DS1347)	+= rtc-ds1347.o
>  obj-$(CONFIG_RTC_DRV_DS1374)	+= rtc-ds1374.o
>  obj-$(CONFIG_RTC_DRV_DS1390)	+= rtc-ds1390.o
>  obj-$(CONFIG_RTC_DRV_DS1511)	+= rtc-ds1511.o
> diff --git a/drivers/rtc/rtc-ds1347.c b/drivers/rtc/rtc-ds1347.c
> new file mode 100644
> index 0000000..3c9a934
> --- /dev/null
> +++ b/drivers/rtc/rtc-ds1347.c
> @@ -0,0 +1,175 @@
> +/* rtc-ds1347.c
> + *
> + * Driver for Dallas Semiconductor DS1347 Low Current, SPI Compatible
> + * Real Time Clock
> + *
> + * Author : Raghavendra Chandra Ganiga <ravi23ganiga@xxxxxxxxx>
> + *
> + * 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/init.h>
> +#include <linux/module.h>
> +#include <linux/device.h>
> +#include <linux/platform_device.h>
> +#include <linux/rtc.h>
> +#include <linux/spi/spi.h>
> +#include <linux/bcd.h>
> +
> +/*Registers in ds1347 rtc*/
> +
> +#define DS1347_SECONDS_REG	0x01
> +#define DS1347_MINUTES_REG	0x03
> +#define DS1347_HOURS_REG	0x05
> +#define DS1347_DATE_REG		0x07
> +#define DS1347_MONTH_REG	0x09
> +#define DS1347_DAY_REG		0x0B
> +#define DS1347_YEAR_REG		0x0D
> +#define DS1347_CONTROL_REG	0x0F
> +#define DS1347_STATUS_REG	0x17
> +#define DS1347_CLOCK_BURST	0x3F
> +
> +
> +
> +static int ds1347_read_reg(struct device *dev, unsigned char address,
> +				unsigned char *data)
> +{
> +	struct spi_device *spi = to_spi_device(dev);
> +
> +	*data = address | 0x80;
> +
> +	return spi_write_then_read(spi, data, 1, data, 1);
> +}
> +
> +static int ds1347_write_reg(struct device *dev, unsigned char address,
> +				unsigned char data)
> +{
> +	struct spi_device *spi = to_spi_device(dev);
> +	unsigned char buf[2];
> +
> +	buf[0] = address & 0x7F;
> +	buf[1] = data;
> +
> +	return spi_write_then_read(spi, buf, 2, NULL, 0);
> +}
> +
> +static int ds1347_read_time(struct device *dev, struct rtc_time *dt)
> +{
> +	struct spi_device *spi = to_spi_device(dev);
> +	int err;
> +	unsigned char buf[8];
> +
> +	buf[0] = DS1347_CLOCK_BURST | 0x80;
> +
> +	err = spi_write_then_read(spi, buf, 1, buf, 8);
> +	if (err)
> +		return err;
> +
> +	dt->tm_sec = bcd2bin(buf[0]);
> +	dt->tm_min = bcd2bin(buf[1]);
> +	dt->tm_hour = bcd2bin(buf[2] & 0x3F);
> +	dt->tm_mday = bcd2bin(buf[3]);
> +	dt->tm_mon = bcd2bin(buf[4]) - 1;
> +	dt->tm_wday = bcd2bin(buf[5]) - 1;
> +	dt->tm_year = bcd2bin(buf[6]) + 100;
> +
> +	return rtc_valid_tm(dt);
> +}
> +
> +static int ds1347_set_time(struct device *dev, struct rtc_time *dt)
> +{
> +	struct spi_device *spi = to_spi_device(dev);
> +	unsigned char buf[9];
> +
> +	buf[0] = DS1347_CLOCK_BURST & 0x7F;
> +	buf[1] = bin2bcd(dt->tm_sec);
> +	buf[2] = bin2bcd(dt->tm_min);
> +	buf[3] = (bin2bcd(dt->tm_hour) & 0x3F);
> +	buf[4] = bin2bcd(dt->tm_mday);
> +	buf[5] = bin2bcd(dt->tm_mon + 1);
> +	buf[6] = bin2bcd(dt->tm_wday + 1);
> +
> +	/*year in linux is from 1900 i.e in range of 100
> +	in rtc it is from 00 to 99 so subtract

 please leave a space after /*

> +	the linux year by 100*/

 and before */

 (ditto for the other comments)

> +	if (dt->tm_year >= 100)
> +		dt->tm_year -= 100;
> +
> +	buf[7] = bin2bcd(dt->tm_year);
> +	buf[8] = bin2bcd(0x00);
> +
> +	/*write the rtc settings*/
> +	return spi_write_then_read(spi, buf, 9, NULL, 0);
> +}
> +
> +
> +

 extra white lines

> +static const struct rtc_class_ops ds1347_rtc_ops = {
> +	.read_time = ds1347_read_time,
> +	.set_time = ds1347_set_time,
> +};
> +
> +static int ds1347_probe(struct spi_device *spi)
> +{
> +	struct rtc_device *rtc;
> +	unsigned char data;
> +	int res;
> +
> +	/*spi setup with ds1347 in mode 3 and bits per word as 8*/
> +	spi->mode = SPI_MODE_3;
> +	spi->bits_per_word = 8;
> +	spi_setup(spi);
> +
> +	/*RTC Settings*/
> +

 unnecessary comment

> +	/*check if spi read is successfull*/

 unnecessary comment, this is pretty clear

> +	res = ds1347_read_reg(&spi->dev, DS1347_SECONDS_REG, &data);
> +	if (res)
> +		return res;
> +
> +	/*Disable the write protect of rtc*/
> +	ds1347_read_reg(&spi->dev, DS1347_CONTROL_REG, &data);
> +	data = data & ~(1<<7);
> +	ds1347_write_reg(&spi->dev, DS1347_CONTROL_REG, data);
> +
> +	/*Enable the oscillator , disable the oscillator stop flag,
> +	 and glitch filter to reduce current consumption*/
> +	ds1347_read_reg(&spi->dev, DS1347_STATUS_REG, &data);
> +	data = data & 0x1B;
> +	ds1347_write_reg(&spi->dev, DS1347_STATUS_REG, data);
> +
> +	/*display the settings*/
> +	ds1347_read_reg(&spi->dev, DS1347_CONTROL_REG, &data);
> +	dev_info(&spi->dev, "DS1347 RTC CTRL Reg = 0x%02x\n", data);
> +
> +	ds1347_read_reg(&spi->dev, DS1347_STATUS_REG, &data);
> +	dev_info(&spi->dev, "DS1347 RTC Status Reg = 0x%02x\n", data);
> +
> +	rtc = devm_rtc_device_register(&spi->dev, "ds1347",
> +				&ds1347_rtc_ops, THIS_MODULE);
> +
> +	if (IS_ERR(rtc))
> +		return PTR_ERR(rtc);
> +
> +	spi_set_drvdata(spi, rtc);
> +
> +	return 0;
> +}
> +
> +static struct spi_driver ds1347_driver = {
> +	.driver = {
> +		.name = "ds1347",
> +		.owner = THIS_MODULE,
> +	},
> +	.probe = ds1347_probe,
> +};
> +
> +module_spi_driver(ds1347_driver);
> +
> +MODULE_DESCRIPTION("DS1347 SPI RTC DRIVER");
> +MODULE_AUTHOR("Raghavendra C Ganiga <ravi23ganiga@xxxxxxxxx>");
> +MODULE_LICENSE("GPL");

 should be GPL v2
 as you declared in the comments at the top of the file.

-- 

 Best regards,

 Alessandro Zummo,
  Tower Technologies - Torino, Italy

  http://www.towertech.it

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