[rtc-linux] [PATCH] rtc: add support for maxim rtc max6916

[rtc-linux] [PATCH] rtc: add support for maxim rtc max6916

[venkat.prashanth2498]

From: venkat-prashanth <venkat.prashanth2498@gmail.com>

This is a patch to add support for
maxim rtc max6916

Signed-off-by:Venkat Prashanth B U <venkat.prashanth2498@gmail.com>
---
---
 rtc-max6916.c | 157 ++++++++++++++++++++++++++++++++++++++++++++++++++++++=
++++
 txtfile       |  11 ++++
 2 files changed, 168 insertions(+)
 create mode 100644 rtc-max6916.c
 create mode 100644 txtfile

diff --git a/rtc-max6916.c b/rtc-max6916.c
new file mode 100644
index 0000000..7fabaa2
--- /dev/null
+++ b/rtc-max6916.c
@@ -0,0 +1,157 @@
+/* rtc-max6916.c
+ *
+ * Driver for MAXIM  max6916 Low Current, SPI Compatible
+ * Real Time Clock
+ *
+ * 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/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 max6916 rtc */
+
+#define MAX6916_SECONDS_REG	0x01
+#define MAX6916_MINUTES_REG	0x02
+#define MAX6916_HOURS_REG	0x03
+#define MAX6916_DATE_REG	0x04
+#define MAX6916_MONTH_REG	0x05
+#define MAX6916_DAY_REG	0x06
+#define MAX6916_YEAR_REG	0x07
+#define MAX6916_CONTROL_REG	0x08
+#define MAX6916_STATUS_REG	0x0C
+#define MAX6916_CLOCK_BURST	0x00
+#define ADDRESS_REG            0x70
+#define DATA_REG               0x71
+#define ADDRESS_REG_MASK       0xe0
+
+static unsigned char get_rtc(unsigned char addr)
+{
+	outb(addr, ADDRESS_REG);
+	return inb(DATA_REG);
+}
+
+static int max6916_read_reg(struct device *dev, unsigned char address,unsi=
gned char *data)
+{
+	struct spi_device *spi =3D to_spi_device(dev);
+	*data =3D address | 0x80;
+	return spi_write_then_read(spi, data, 1, data, 1);
+}
+
+static int max6916_write_reg(struct device *dev, unsigned char address,uns=
igned char data)
+{
+	struct spi_device *spi =3D to_spi_device(dev);
+	unsigned char buf[2];
+	buf[0] =3D address & 0x7F;
+	buf[1] =3D data;
+	return spi_write_then_read(spi, buf, 2, NULL, 0);
+}
+
+static int max6916_read_time(struct device *dev, struct rtc_time *dt)
+{
+	struct spi_device *spi =3D to_spi_device(dev);
+	int err;
+	unsigned char buf[8];
+	buf[0] =3D MAX6916_CLOCK_BURST | 0x80;
+	err =3D spi_write_then_read(spi, buf, 1, buf, 8);
+	if (err)
+	return err;
+	dt->tm_sec =3D get_rtc(buf[0]);
+	dt->tm_min =3D get_rtc(buf[1]);
+	dt->tm_hour =3D get_rtc(buf[2] & 0x00);
+	dt->tm_mday =3D get_rtc(buf[3]);
+	dt->tm_mon =3D get_rtc(buf[4]) - 1;
+	dt->tm_wday =3D get_rtc(buf[5]) - 1;
+	dt->tm_year =3D get_rtc(buf[6]) + 100;
+	return rtc_valid_tm(dt);
+}
+
+static int max6916_set_time(struct device *dev, struct rtc_time *dt)
+{
+	struct spi_device *spi =3D to_spi_device(dev);
+	unsigned char buf[9];
+
+	buf[0] =3D MAX6916_CLOCK_BURST & 0x7F;
+	buf[1] =3D bcd2bin(dt->tm_sec);
+	buf[2] =3D bcd2bin(dt->tm_min);
+	buf[3] =3D (bcd2bin(dt->tm_hour) & 0x00);
+	buf[4] =3D bcd2bin(dt->tm_mday);
+	buf[5] =3D bcd2bin(dt->tm_mon + 1);
+	buf[6] =3D bcd2bin(dt->tm_wday + 1);
+
+	/* year in linux is from 1900 i.e in range of 100
+	in rtc it is from 00 to 99 */
+	dt->tm_year =3D dt->tm_year % 100;
+
+	buf[7] =3D bcd2bin(dt->tm_year);
+	buf[8] =3D bcd2bin(0x00);
+
+	/* write the rtc settings */
+	return spi_write_then_read(spi, buf, 9, NULL, 0);
+}
+
+static const struct rtc_class_ops max6916_rtc_ops =3D {
+	.read_time =3D max6916_read_time,
+	.set_time =3D max6916_set_time,
+};
+
+static int max6916_probe(struct spi_device *spi)
+{
+	struct rtc_device *rtc;
+	unsigned char data;
+	int res;
+
+	/* spi setup with max6916 in mode 3 and bits per word as 8 */
+	spi->mode =3D SPI_MODE_3;
+	spi->bits_per_word =3D 8;
+	spi_setup(spi);
+
+	/* RTC Settings */
+	res =3D max6916_read_reg(&spi->dev, MAX6916_SECONDS_REG, &data);
+	if (res)
+	return res;
+	/* Disable the write protect of rtc */
+	max6916_read_reg(&spi->dev, MAX6916_CONTROL_REG, &data);
+	data =3D data & ~(1<<7);
+	max6916_write_reg(&spi->dev, MAX6916_CONTROL_REG, data);
+	/* Enable the oscillator , disable the oscillator stop flag,
+	 and glitch filter to reduce current consumption */
+	max6916_read_reg(&spi->dev, MAX6916_STATUS_REG, &data);
+	data =3D data & 0x1B;
+	max6916_write_reg(&spi->dev, MAX6916_STATUS_REG, data);
+	/* display the settings */
+	max6916_read_reg(&spi->dev, MAX6916_CONTROL_REG, &data);
+	dev_info(&spi->dev, "MAX6916 RTC CTRL Reg =3D 0x%02x\n", data);
+	max6916_read_reg(&spi->dev, MAX6916_STATUS_REG, &data);
+	dev_info(&spi->dev, "MAX6916 RTC Status Reg =3D 0x%02x\n", data);
+	rtc =3D devm_rtc_device_register(&spi->dev, "max6916",&max6916_rtc_ops, T=
HIS_MODULE);
+	if (IS_ERR(rtc))
+	return PTR_ERR(rtc);
+	spi_set_drvdata(spi, rtc);
+
+	return 0;
+}
+static struct spi_driver max6916_driver =3D {
+	.driver =3D {
+	.name =3D "max6916",
+	},
+	.probe =3D max6916_probe,
+};
+static void __exit rtc_exit(void)
+{
+	pr_info("rtc module unloaded\n");
+}
+
+module_spi_driver(max6916_driver);
+MODULE_DESCRIPTION("MAX6916 SPI RTC DRIVER");
+MODULE_AUTHOR("Venkat Prashanth B U <venkat.prashanth2498@gmail.com>");
+MODULE_LICENSE("GPL v2");
diff --git a/txtfile b/txtfile
new file mode 100644
index 0000000..1604409
--- /dev/null
+++ b/txtfile
@@ -0,0 +1,11 @@
+config RTC_DRV_MAX6916
+tristate "Maxim MAX6916"
+
+help=20
+  If you say yes here you get support for the=20
+  Maxim MAX6916 chips.=20
+  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=E2=80=90max6916.
--=20
1.9.2

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Re: [rtc-linux] [PATCH] rtc: add support for maxim rtc max6916

[Alexandre Belloni]

Hi,

Please use checkpatch before submitting.

On 03/05/2016 at 04:00:40 -0700, venkat.prashanth2498@gmail.com wrote :
> From: venkat-prashanth <venkat.prashanth2498@gmail.com>
> 
> This is a patch to add support for
> maxim rtc max6916
> 
> Signed-off-by:Venkat Prashanth B U <venkat.prashanth2498@gmail.com>
> ---
> ---
>  rtc-max6916.c | 157 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++

This will not apply, that driver has to be in drivers/rtc

>  txtfile       |  11 ++++

What is that file?

>  2 files changed, 168 insertions(+)
>  create mode 100644 rtc-max6916.c
>  create mode 100644 txtfile
> 
> diff --git a/rtc-max6916.c b/rtc-max6916.c
> new file mode 100644
> index 0000000..7fabaa2
> --- /dev/null
> +++ b/rtc-max6916.c
> @@ -0,0 +1,157 @@
> +/* rtc-max6916.c
> + *
> + * Driver for MAXIM  max6916 Low Current, SPI Compatible
> + * Real Time Clock
> + *
> + * 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/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 max6916 rtc */
> +
> +#define MAX6916_SECONDS_REG	0x01
> +#define MAX6916_MINUTES_REG	0x02
> +#define MAX6916_HOURS_REG	0x03
> +#define MAX6916_DATE_REG	0x04
> +#define MAX6916_MONTH_REG	0x05
> +#define MAX6916_DAY_REG	0x06
> +#define MAX6916_YEAR_REG	0x07
> +#define MAX6916_CONTROL_REG	0x08
> +#define MAX6916_STATUS_REG	0x0C
> +#define MAX6916_CLOCK_BURST	0x00
> +#define ADDRESS_REG            0x70
> +#define DATA_REG               0x71
> +#define ADDRESS_REG_MASK       0xe0
> +
> +static unsigned char get_rtc(unsigned char addr)
> +{
> +	outb(addr, ADDRESS_REG);
> +	return inb(DATA_REG);

What is the use of those port IOs?

> +}
> +
> +static int max6916_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 max6916_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 max6916_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] = MAX6916_CLOCK_BURST | 0x80;
> +	err = spi_write_then_read(spi, buf, 1, buf, 8);
> +	if (err)
> +	return err;
> +	dt->tm_sec = get_rtc(buf[0]);
> +	dt->tm_min = get_rtc(buf[1]);
> +	dt->tm_hour = get_rtc(buf[2] & 0x00);

How can that work?

> +	dt->tm_mday = get_rtc(buf[3]);
> +	dt->tm_mon = get_rtc(buf[4]) - 1;
> +	dt->tm_wday = get_rtc(buf[5]) - 1;
> +	dt->tm_year = get_rtc(buf[6]) + 100;
> +	return rtc_valid_tm(dt);
> +}
> +
> +static int max6916_set_time(struct device *dev, struct rtc_time *dt)
> +{
> +	struct spi_device *spi = to_spi_device(dev);
> +	unsigned char buf[9];
> +
> +	buf[0] = MAX6916_CLOCK_BURST & 0x7F;
> +	buf[1] = bcd2bin(dt->tm_sec);
> +	buf[2] = bcd2bin(dt->tm_min);
> +	buf[3] = (bcd2bin(dt->tm_hour) & 0x00);

Same question, this is always setting 0...

> +	buf[4] = bcd2bin(dt->tm_mday);
> +	buf[5] = bcd2bin(dt->tm_mon + 1);
> +	buf[6] = bcd2bin(dt->tm_wday + 1);
> +
> +	/* year in linux is from 1900 i.e in range of 100
> +	in rtc it is from 00 to 99 */
> +	dt->tm_year = dt->tm_year % 100;

You should enforce the year range instead of accepting any value.

> +
> +	buf[7] = bcd2bin(dt->tm_year);
> +	buf[8] = bcd2bin(0x00);
> +
> +	/* write the rtc settings */
> +	return spi_write_then_read(spi, buf, 9, NULL, 0);
> +}
> +
> +static const struct rtc_class_ops max6916_rtc_ops = {
> +	.read_time = max6916_read_time,
> +	.set_time = max6916_set_time,
> +};
> +
> +static int max6916_probe(struct spi_device *spi)
> +{
> +	struct rtc_device *rtc;
> +	unsigned char data;
> +	int res;
> +
> +	/* spi setup with max6916 in mode 3 and bits per word as 8 */
> +	spi->mode = SPI_MODE_3;
> +	spi->bits_per_word = 8;
> +	spi_setup(spi);
> +
> +	/* RTC Settings */
> +	res = max6916_read_reg(&spi->dev, MAX6916_SECONDS_REG, &data);
> +	if (res)
> +	return res;
> +	/* Disable the write protect of rtc */
> +	max6916_read_reg(&spi->dev, MAX6916_CONTROL_REG, &data);
> +	data = data & ~(1<<7);
> +	max6916_write_reg(&spi->dev, MAX6916_CONTROL_REG, data);
> +	/* Enable the oscillator , disable the oscillator stop flag,
> +	 and glitch filter to reduce current consumption */
> +	max6916_read_reg(&spi->dev, MAX6916_STATUS_REG, &data);
> +	data = data & 0x1B;
> +	max6916_write_reg(&spi->dev, MAX6916_STATUS_REG, data);
> +	/* display the settings */
> +	max6916_read_reg(&spi->dev, MAX6916_CONTROL_REG, &data);
> +	dev_info(&spi->dev, "MAX6916 RTC CTRL Reg = 0x%02x\n", data);
> +	max6916_read_reg(&spi->dev, MAX6916_STATUS_REG, &data);
> +	dev_info(&spi->dev, "MAX6916 RTC Status Reg = 0x%02x\n", data);
> +	rtc = devm_rtc_device_register(&spi->dev, "max6916",&max6916_rtc_ops, THIS_MODULE);
> +	if (IS_ERR(rtc))
> +	return PTR_ERR(rtc);
> +	spi_set_drvdata(spi, rtc);
> +
> +	return 0;
> +}
> +static struct spi_driver max6916_driver = {
> +	.driver = {
> +	.name = "max6916",
> +	},
> +	.probe = max6916_probe,
> +};
> +static void __exit rtc_exit(void)
> +{
> +	pr_info("rtc module unloaded\n");
> +}
> +
> +module_spi_driver(max6916_driver);
> +MODULE_DESCRIPTION("MAX6916 SPI RTC DRIVER");
> +MODULE_AUTHOR("Venkat Prashanth B U <venkat.prashanth2498@gmail.com>");
> +MODULE_LICENSE("GPL v2");
> diff --git a/txtfile b/txtfile
> new file mode 100644
> index 0000000..1604409
> --- /dev/null
> +++ b/txtfile
> @@ -0,0 +1,11 @@
> +config RTC_DRV_MAX6916
> +tristate "Maxim MAX6916"
> +
> +help 
> +  If you say yes here you get support for the 
> +  Maxim MAX6916 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‐max6916.

Ok, this should go in drivers/rtc/Kconfig

-- 
Alexandre Belloni, Free Electrons
Embedded Linux, Kernel and Android engineering
http://free-electrons.com

[rtc-linux] [PATCH] rtc:add support for maxim rtc max6916

[venkat.prashanth2498]

From: venkat-prashanth <venkat.prashanth2498@gmail.com>

This is a patch to add support for
maxim rtc max6916
Signed-off-by:Venkat Prashanth B U <venkat.prashanth2498@gmail.com>
---
 Kconfig       |   9 ++++
 Makefile      |   6 +++
 rtc-max6916.c | 133 ++++++++++++++++++++++++++++++++++++++++++++++++++++++=
++++
 3 files changed, 148 insertions(+)
 create mode 100644 Kconfig
 create mode 100644 Makefile
 create mode 100644 rtc-max6916.c
diff --git a/drivers/rtc/Kconfig b/drivers/rtc/Kconfig
new file mode 100644
index 0000000..fa7a2fa
--- a/drivers/rtc/Kconfig
+++ b/drivers/rtc/Kconfig
@@ -0,0 +1,9 @@
+config RTC_DRV_MAX6916
+tristate "Maxim MAX6916"
+ help
+  If you say yes here you get support for the
+  Maxim MAX6916 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=E2=80=90max6916.
diff --git a/drivers/rtc/Makefile b/drivers/rtc/Makefile
new file mode 100644
index 0000000..db34a02
--- a/drivers/rtc/Makefile
+++ b/drivers/rtc/Makefile
@@ -0,0 +1,6 @@
+CONFIG_MODULE_SIG=3Dn
+obj-m+=3Drtc-max6916.o
+all:
+	make -C /lib/modules/$(shell uname -r)/build M=3D$(PWD) modules
+clean:
+	make -C /lib/modules/$(shell uname -r)/build M=3D$(PWD) clean
diff --git a/drivers/rtc/rtc-max6916.c b/drivers/rtc/rtc-max6916.c
new file mode 100644
index 0000000..8e9bcdc
--- a/drivers/rtc/rtc-max6916.c
+++ b/drivers/rtc/rtc-max6916.c
@@ -0,0 +1,133 @@
+/* rtc-max6916.c
+ *
+ * Driver for MAXIM  max6916 Low Current, SPI Compatible
+ * Real Time Clock
+ *
+ * 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/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 max6916 rtc */
+#define MAX6916_SECONDS_REG	0x01
+#define MAX6916_MINUTES_REG	0x02
+#define MAX6916_HOURS_REG	0x03
+#define MAX6916_DATE_REG	0x04
+#define MAX6916_MONTH_REG	0x05
+#define MAX6916_DAY_REG	0x06
+#define MAX6916_YEAR_REG	0x07
+#define MAX6916_CONTROL_REG	0x08
+#define MAX6916_STATUS_REG	0x0C
+#define MAX6916_CLOCK_BURST	0x00
+
+static int max6916_read_reg(struct device *dev, unsigned char address, uns=
igned char *data)
+{
+	struct spi_device *spi =3D to_spi_device(dev);
+	*data =3D address | 0x80;
+	return spi_write_then_read(spi, data, 1, data, 1);
+}
+
+static int max6916_write_reg(struct device *dev, unsigned char address, un=
signed char data)
+{
+	struct spi_device *spi =3D to_spi_device(dev);
+	unsigned char buf[2];
+
+	buf[0] =3D address&0x7F;
+	buf[1] =3D data;
+	return spi_write_then_read(spi, buf, 2, NULL, 0);
+}
+
+static int max6916_read_time(struct device *dev, struct rtc_time *dt)
+{
+	struct spi_device *spi =3D to_spi_device(dev);
+	int err;
+	unsigned char buf[8];
+
+	buf[0] =3D MAX6916_CLOCK_BURST | 0x80;
+	err =3D spi_write_then_read(spi, buf, 1, buf, 8);
+	if (err)
+	return err;
+	dt->tm_sec =3D bcd2bin(buf[0]);
+	dt->tm_min =3D bcd2bin(buf[1]);
+	dt->tm_hour =3D bcd2bin(buf[2] & MAX6916_CLOCK_BURST);
+	dt->tm_mday =3D bcd2bin(buf[3]);
+	dt->tm_mon =3D bcd2bin(buf[4]) - 1;
+	dt->tm_wday =3D bcd2bin(buf[5]) - 1;
+	dt->tm_year =3D bcd2bin(buf[6]) + 100;
+	return rtc_valid_tm(dt);
+}
+static int max6916_set_time(struct device *dev, struct rtc_time *dt)
+{
+	struct spi_device *spi =3D to_spi_device(dev);
+	unsigned char buf[9];
+
+	buf[0] =3D MAX6916_CLOCK_BURST & 0x7F;
+	buf[1] =3D bcd2bin(dt->tm_sec);
+	buf[2] =3D bcd2bin(dt->tm_min);
+	buf[3] =3D (bcd2bin(dt->tm_hour)&MAX6916_CLOCK_BURST);
+	buf[4] =3D bcd2bin(dt->tm_mday);
+	buf[5] =3D bcd2bin(dt->tm_mon + 1);
+	buf[6] =3D bcd2bin(dt->tm_wday + 1);
+	/* year from 1900-range of 100 in rtc from 00 to 99 */
+	dt->tm_year =3D dt->tm_year % 100;
+	buf[7] =3D bcd2bin(dt->tm_year);
+	buf[8] =3D bcd2bin(0x00);
+	/* write the rtc settings */
+	return spi_write_then_read(spi, buf, 9, NULL, 0);
+}
+static const struct rtc_class_ops max6916_rtc_ops =3D {
+	.read_time =3D max6916_read_time,
+	.set_time =3D max6916_set_time,
+};
+static int max6916_probe(struct spi_device *spi)
+{
+	struct rtc_device *rtc;
+	unsigned char data;
+	int res;
+
+	/* spi setup with max6916 in mode 3 and bits per word as 8 */
+	spi->mode =3D SPI_MODE_3;
+	spi->bits_per_word =3D 8;
+	spi_setup(spi);
+	/* RTC Settings */
+	res =3D max6916_read_reg(&spi->dev, MAX6916_SECONDS_REG, &data);
+	if (res)
+	return res;
+	/* Disable the write protect of rtc */
+	max6916_read_reg(&spi->dev, MAX6916_CONTROL_REG, &data);
+	data =3D data & ~(1<<7);
+	max6916_write_reg(&spi->dev, MAX6916_CONTROL_REG, data);
+	/* Enable the oscillator,disable the oscillator stop flag,and glitch filt=
er to reduce current consumption */
+	max6916_read_reg(&spi->dev, MAX6916_STATUS_REG, &data);
+	data =3D data & 0x1B;
+	max6916_write_reg(&spi->dev, MAX6916_STATUS_REG, data);
+	/* display the settings */
+	max6916_read_reg(&spi->dev, MAX6916_CONTROL_REG, &data);
+	dev_info(&spi->dev, "MAX6916 RTC CTRL Reg =3D 0x%02x\n", data);
+	max6916_read_reg(&spi->dev, MAX6916_STATUS_REG, &data);
+	dev_info(&spi->dev, "MAX6916 RTC Status Reg =3D 0x%02x\n", data);
+	rtc =3D devm_rtc_device_register(&spi->dev, "max6916", &max6916_rtc_ops, =
THIS_MODULE);
+	if (IS_ERR(rtc))
+	return PTR_ERR(rtc);
+	spi_set_drvdata(spi, rtc);
+	return 0;
+}
+static struct spi_driver max6916_driver =3D {
+	.driver =3D {
+	.name =3D "max6916",
+	},
+	.probe =3D max6916_probe,
+};
+module_spi_driver(max6916_driver);
+MODULE_DESCRIPTION("MAX6916 SPI RTC DRIVER");
+MODULE_AUTHOR("Venkat Prashanth B U <venkat.prashanth2498@gmail.com>");
+MODULE_LICENSE("GPL v2");
--=20
1.9.2

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[rtc-linux] [PATCH] rtc: add support for maxim rtc max6916

[venkat.prashanth2498]

From: venkat-prashanth <venkat.prashanth2498@gmail.com>

This a patch to add support for
maxim rtc max6916

Signed-off-by: Venkat Prashanth B U <venkat.prashanth2498@gmail.com>
---
---
 drivers/rtc/rtc-max6916.c | 165 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 165 insertions(+)

diff --git a/drivers/rtc/rtc-max6916.c b/drivers/rtc/rtc-max6916.c
index e69de29..2085151 100644
--- a/drivers/rtc/rtc-max6916.c
+++ b/drivers/rtc/rtc-max6916.c
@@ -0,0 +1,165 @@
+/* rtc-max6916.c
+ *
+ * Driver for MAXIM  max6916 Low Current, SPI Compatible
+ * Real Time Clock
+ *
+ * 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/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 max6916 rtc */
+
+#define MAX6916_SECONDS_REG	0x01
+#define MAX6916_MINUTES_REG	0x02
+#define MAX6916_HOURS_REG	   0x03
+#define MAX6916_DATE_REG	   0x04
+#define MAX6916_MONTH_REG	   0x05
+#define MAX6916_DAY_REG	   0x06
+#define MAX6916_YEAR_REG	   0x07
+#define MAX6916_CONTROL_REG	0x08
+#define MAX6916_STATUS_REG	0x0C
+#define MAX6916_CLOCK_BURST	0x00
+
+static int max6916_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 max6916_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 max6916_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] = MAX6916_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] & MAX6916_CLOCK_BURST);
+	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 max6916_set_time(struct device *dev, struct rtc_time *dt)
+{
+	struct spi_device *spi = to_spi_device(dev);
+	unsigned char buf[9];
+
+	buf[0] = MAX6916_CLOCK_BURST & 0x7F;
+	buf[1] = bcd2bin(dt->tm_sec);
+	buf[2] = bcd2bin(dt->tm_min);
+	buf[3] = (bcd2bin(dt->tm_hour)&MAX6916_CLOCK_BURST);
+	buf[4] = bcd2bin(dt->tm_mday);
+	buf[5] = bcd2bin(dt->tm_mon + 1);
+	buf[6] = bcd2bin(dt->tm_wday + 1);
+
+	/* year from 1900-range of 100 in rtc from 00 to 99 */
+	dt->tm_year = dt->tm_year % 100;
+
+	buf[7] = bcd2bin(dt->tm_year);
+	buf[8] = bcd2bin(0x00);
+	
+	/* write the rtc settings */
+	return spi_write_then_read(spi, buf, 9, NULL, 0);
+}
+
+static const struct rtc_class_ops max6916_rtc_ops = {
+	.read_time = max6916_read_time,
+	.set_time = max6916_set_time,
+};
+
+static int max6916_probe(struct spi_device *spi)
+{
+	struct rtc_device *rtc;
+	unsigned char data;
+	int res;
+
+	/* spi setup with max6916 in mode 3 and bits per word as 8 */
+	spi->mode = SPI_MODE_3;
+	spi->bits_per_word = 8;
+	spi_setup(spi);
+
+	/* RTC Settings */
+	res = max6916_read_reg(&spi->dev, MAX6916_SECONDS_REG, &data);
+	
+	if (res)
+		return res;
+
+	/* Disable the write protect of rtc */
+	max6916_read_reg(&spi->dev, MAX6916_CONTROL_REG, &data);
+	data = data & ~(1<<7);
+	max6916_write_reg(&spi->dev, MAX6916_CONTROL_REG, data);
+
+	/* Enable the oscillator,disable the oscillator stop flag,
+	and glitch filter to reduce current consumption */
+	max6916_read_reg(&spi->dev, MAX6916_STATUS_REG, &data);
+	data = data & 0x1B;
+	max6916_write_reg(&spi->dev, MAX6916_STATUS_REG, data);
+
+	/* display the settings */
+	max6916_read_reg(&spi->dev, MAX6916_CONTROL_REG, &data);
+	dev_info(&spi->dev, "MAX6916 RTC CTRL Reg = 0x%02x\n", data);
+
+	max6916_read_reg(&spi->dev, MAX6916_STATUS_REG, &data);
+	dev_info(&spi->dev, "MAX6916 RTC Status Reg = 0x%02x\n", data);
+
+	rtc = devm_rtc_device_register(&spi->dev, "max6916", 
+			      &max6916_rtc_ops, THIS_MODULE);
+			      
+	if (IS_ERR(rtc))
+		return PTR_ERR(rtc);
+		
+	spi_set_drvdata(spi, rtc);
+
+	return 0;
+}
+
+static struct spi_driver max6916_driver = {
+	.driver = {
+	.name = "max6916",
+	},
+	.probe = max6916_probe,
+};
+
+module_spi_driver(max6916_driver);
+
+MODULE_DESCRIPTION("MAX6916 SPI RTC DRIVER");
+MODULE_AUTHOR("Venkat Prashanth B U <venkat.prashanth2498@gmail.com>");
+MODULE_LICENSE("GPL v2");
-- 
1.9.2

-- 
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