Message-ID: <20161012113946.pr2mi5j3watelpng@piout.net>
Date:   Wed, 12 Oct 2016 13:39:46 +0200
From:   Alexandre Belloni <alexandre.belloni@...e-electrons.com>
To:     VENKAT PRASHANTH B U <venkat.prashanth2498@...il.com>
Cc:     rtc-linux@...glegroups.com, linux-kernel@...r.kernel.org
Subject: Re: [rtc-linux] [PATCH] rtc: Add support for maxim dallas rtc
 max-6917

Hi,

Seeing this has the same register map as max6916, please use regmap to
abstract the accesses and handle both with the same driver. You can have
a look at rtc-ds3232.c for an example.

On 12/10/2016 at 01:33:32 -0700, VENKAT PRASHANTH B U wrote :
> This is a patch to add support for
> maxim dallas rtc max6917.
> 
> Signed-off-by: Venkat Prashanth B U <venkat.prashanth2498@...il.com>
> ---
> ---
>  drivers/rtc/Kconfig       |   9 +
>  drivers/rtc/Makefile      |   1 +
>  drivers/rtc/rtc-max6917.c | 406 ++++++++++++++++++++++++++++++++++++++++++++++
>  3 files changed, 416 insertions(+)
> 
> diff --git a/drivers/rtc/Kconfig b/drivers/rtc/Kconfig
> index e215f50..2163606 100644
> --- a/drivers/rtc/Kconfig
> +++ b/drivers/rtc/Kconfig
> @@ -277,6 +277,15 @@ config RTC_DRV_MAX6900
>  	  This driver can also be built as a module. If so, the module
>  	  will be called rtc-max6900.
>  
> +config RTC_DRV_MAX6917
> +	tristate "Maxim MAX6917"
> +	help
> +	  If you say yes here you will get support for the
> +	  Maxim MAX6917 I2C RTC chip.
> +
> +	  This driver can also be built as a module. If so, the module
> +	  will be called rtc-max6917.
> +
>  config RTC_DRV_MAX8907
>  	tristate "Maxim MAX8907"
>  	depends on MFD_MAX8907
> diff --git a/drivers/rtc/Makefile b/drivers/rtc/Makefile
> index 7cf7ad5..29332fb 100644
> --- a/drivers/rtc/Makefile
> +++ b/drivers/rtc/Makefile
> @@ -87,6 +87,7 @@ obj-$(CONFIG_RTC_DRV_M48T86)	+= rtc-m48t86.o
>  obj-$(CONFIG_RTC_DRV_MAX6900)	+= rtc-max6900.o
>  obj-$(CONFIG_RTC_DRV_MAX6902)	+= rtc-max6902.o
>  obj-$(CONFIG_RTC_DRV_MAX6916)	+= rtc-max6916.o
> +obj-$(CONFIG_RTC_DRV_MAX6917)	+= rtc-max6917.o
>  obj-$(CONFIG_RTC_DRV_MAX77686)	+= rtc-max77686.o
>  obj-$(CONFIG_RTC_DRV_MAX8907)	+= rtc-max8907.o
>  obj-$(CONFIG_RTC_DRV_MAX8925)	+= rtc-max8925.o
> diff --git a/drivers/rtc/rtc-max6917.c b/drivers/rtc/rtc-max6917.c
> index e69de29..1176384 100644
> --- a/drivers/rtc/rtc-max6917.c
> +++ b/drivers/rtc/rtc-max6917.c
> @@ -0,0 +1,406 @@
> +	/* rtc-max6917.c
> +	*
> +	* Driver for MAXIM  max6917  I2C-Compatible Real Time Clock
> +	*
> +	* Author : Venkat Prashanth B U <venkat.prashanth2498@...il.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/bcd.h>
> +	#include <linux/i2c.h>
> +	#include <linux/init.h>
> +	#include <linux/module.h>
> +	#include <linux/rtc.h>
> +	#include <linux/string.h>
> +	#include <linux/delay.h>
> +	#include <linux/clk-provider.h>
> +	#include <linux/slab.h>
> +
> +	#define MAX6917_REG_SECS		0x01	/* 00-59 */
> +	#define MAX6917_REG_MIN			0x02	/* 00-59 */
> +	#define MAX6917_REG_HOUR		0x03	/* 00-23, or 1-12{am,pm} */
> +	#define MAX6917_REG_WDAY		0x04	/* 01-07 */
> +	#define MAX6917_REG_MDAY		0x05	/* 01-31 */
> +	#define MAX6917_REG_MONTH		0x06	/* 01-12 */
> +	#define MAX6917_REG_YEAR		0x07	/* 00-99 */
> +	#define MAX6917_REG_CONTROL		0x08
> +	#define MAX6917_REG_STATUS		0x0c
> +	#define MAX6917_REG_ALARM		0x0a
> +	#define MAX6917_BURST_LEN		8	/* can burst r/w first 8 regs */
> +	#define MAX6917_REG_CENTURY		9	/* century */
> +	#define MAX6917_REG_LEN			10
> +	#define MAX6917_REG_CT_WP		(1 << 7)	/* Write Protect */
> +	/*
> +	* register read/write commands
> +	*/
> +	#define MAX6917_REG_CONTROL_WRITE	0x8e
> +	#define MAX6917_REG_CENTURY_WRITE	0x92
> +	#define MAX6917_REG_CENTURY_READ	0x93
> +	#define MAX6917_REG_RESERVED_READ	0x96
> +	#define MAX6917_REG_BURST_WRITE		0xbe
> +	#define MAX6917_REG_BURST_READ		0xbf
> +
> +	#define MAX6917_IDLE_TIME_AFTER_WRITE	3	/* specification says 2.5 mS */
> +
> +	static struct i2c_driver max6917_driver;
> +
> +	struct max6917
> +	{
> +	u8 offset;			/* register's offset */
> +	u8 regs[11];
> +	u16 nvram_offset;
> +	struct bin_attribute *nvram;
> +	unsigned long flags;
> +	#define HAS_NVRAM			0	/* bit 0 == sysfs file active */
> +	#define HAS_ALARM			1	/* bit 1 == irq claimed */
> +	struct i2c_client *client;
> +	struct rtc_device *rtc;
> +		s32 (*read_block_data) (const struct i2c_client * client, u8 command,
> +					u8 length, u8 * values);
> +		s32 (*write_block_data) (const struct i2c_client * client, u8 command,
> +					u8 length, const u8 * values);
> +	};
> +
> +	struct chip_desc
> +	{
> +	unsigned alarm:1;
> +	u16 nvram_offset;
> +	u16 nvram_size;
> +	};
> +
> +	static int
> +	max6917_i2c_read_regs (struct i2c_client *client, u8 * buf)
> +	{
> +	u8 reg_burst_read[1] = { MAX6917_REG_BURST_READ };
> +	u8 reg_century_read[1] = { MAX6917_REG_CENTURY_READ };
> +	struct i2c_msg msgs[4] = {
> +		{
> +		.addr = client->addr,
> +		.flags = 0,		/* write */
> +		.len = sizeof (reg_burst_read),
> +		.buf = reg_burst_read}
> +		,
> +		{
> +		.addr = client->addr,
> +		.flags = I2C_M_RD,
> +		.len = MAX6917_BURST_LEN,
> +		.buf = buf}
> +		,
> +		{
> +		.addr = client->addr,
> +		.flags = 0,		/* write */
> +		.len = sizeof (reg_century_read),
> +		.buf = reg_century_read}
> +		,
> +		{
> +		.addr = client->addr,
> +		.flags = I2C_M_RD,
> +		.len = sizeof (buf[MAX6917_REG_CENTURY]),
> +		.buf = &buf[MAX6917_REG_CENTURY]}
> +	};
> +	int rc;
> +
> +	rc = i2c_transfer (client->adapter, msgs, ARRAY_SIZE (msgs));
> +	if (rc != ARRAY_SIZE (msgs))
> +		{
> +			dev_err (&client->dev, "%s: register read failed\n", __func__);
> +			return -EIO;
> +		}
> +	return 0;
> +	}
> +
> +	static int
> +	max6917_i2c_write_regs (struct i2c_client *client, u8 const *buf)
> +	{
> +	u8 i2c_century_buf[1 + 1] = { MAX6917_REG_CENTURY_WRITE };
> +	struct i2c_msg century_msgs[1] = {
> +		{
> +		.addr = client->addr,
> +		.flags = 0,		/* write */
> +		.len = sizeof (i2c_century_buf),
> +		.buf = i2c_century_buf}
> +	};
> +	u8 i2c_burst_buf[MAX6917_BURST_LEN + 1] = { MAX6917_REG_BURST_WRITE };
> +	struct i2c_msg burst_msgs[1] = {
> +		{
> +		.addr = client->addr,
> +		.flags = 0,		/* write */
> +		.len = sizeof (i2c_burst_buf),
> +		.buf = i2c_burst_buf}
> +	};
> +	int rc;
> +
> +	/*
> +		* We have to make separate calls to i2c_transfer because of
> +		* the need to delay after each write to the chip.  Also,
> +		* we write the century byte first, since we set the write-protect
> +		* bit as part of the burst write.
> +		*/
> +	i2c_century_buf[1] = buf[MAX6917_REG_CENTURY];
> +
> +	rc = i2c_transfer (client->adapter, century_msgs,
> +				ARRAY_SIZE (century_msgs));
> +	if (rc != ARRAY_SIZE (century_msgs))
> +		goto write_failed;
> +
> +	msleep (MAX6917_IDLE_TIME_AFTER_WRITE);
> +
> +	memcpy (&i2c_burst_buf[1], buf, MAX6917_BURST_LEN);
> +
> +	rc = i2c_transfer (client->adapter, burst_msgs, ARRAY_SIZE (burst_msgs));
> +	if (rc != ARRAY_SIZE (burst_msgs))
> +		goto write_failed;
> +	msleep (MAX6917_IDLE_TIME_AFTER_WRITE);
> +
> +	return 0;
> +
> +	write_failed:
> +	dev_err (&client->dev, "%s: register write failed\n", __func__);
> +	return -EIO;
> +	}
> +
> +	static int
> +	max6917_i2c_read_time (struct i2c_client *client, struct rtc_time *tm)
> +	{
> +	int rc;
> +	u8 regs[MAX6917_REG_LEN];
> +
> +	rc = max6917_i2c_read_regs (client, regs);
> +	if (rc < 0)
> +		return rc;
> +
> +	tm->tm_sec = bcd2bin (regs[MAX6917_REG_SECS]);
> +	tm->tm_min = bcd2bin (regs[MAX6917_REG_MIN]);
> +	tm->tm_hour = bcd2bin (regs[MAX6917_REG_HOUR] & 0x3f);
> +	tm->tm_mday = bcd2bin (regs[MAX6917_REG_MDAY]);
> +	tm->tm_mon = bcd2bin (regs[MAX6917_REG_MONTH]) - 1;
> +	tm->tm_year = bcd2bin (regs[MAX6917_REG_YEAR]) +
> +		bcd2bin (regs[MAX6917_REG_CENTURY]) * 100 - 1900;
> +	tm->tm_wday = bcd2bin (regs[MAX6917_REG_WDAY]);
> +
> +	return rtc_valid_tm (tm);
> +	}
> +
> +	static int
> +	max6917_i2c_clear_write_protect (struct i2c_client *client)
> +	{
> +	return i2c_smbus_write_byte_data (client, MAX6917_REG_CONTROL_WRITE, 0);
> +	}
> +
> +	static int
> +	max6917_i2c_set_time (struct i2c_client *client, struct rtc_time const *tm)
> +	{
> +	u8 regs[MAX6917_REG_LEN];
> +	int rc;
> +
> +	rc = max6917_i2c_clear_write_protect (client);
> +	if (rc < 0)
> +		return rc;
> +
> +	regs[MAX6917_REG_SECS] = bin2bcd (tm->tm_sec);
> +	regs[MAX6917_REG_MIN] = bin2bcd (tm->tm_min);
> +	regs[MAX6917_REG_HOUR] = bin2bcd (tm->tm_hour);
> +	regs[MAX6917_REG_MDAY] = bin2bcd (tm->tm_mday);
> +	regs[MAX6917_REG_MONTH] = bin2bcd (tm->tm_mon + 1);
> +	regs[MAX6917_REG_WDAY] = bin2bcd (tm->tm_wday);
> +	regs[MAX6917_REG_YEAR] = bin2bcd (tm->tm_year % 100);
> +	regs[MAX6917_REG_CENTURY] = bin2bcd ((tm->tm_year + 1900) / 100);
> +	/* set write protect */
> +	regs[MAX6917_REG_CONTROL] = MAX6917_REG_CT_WP;
> +
> +	rc = max6917_i2c_write_regs (client, regs);
> +	if (rc < 0)
> +		return rc;
> +
> +	return 0;
> +	}
> +
> +	static int
> +	max6917_rtc_read_time (struct device *dev, struct rtc_time *tm)
> +	{
> +	return max6917_i2c_read_time (to_i2c_client (dev), tm);
> +	}
> +
> +	static int
> +	max6917_rtc_set_time (struct device *dev, struct rtc_time *tm)
> +	{
> +	return max6917_i2c_set_time (to_i2c_client (dev), tm);
> +	}
> +
> +	static int
> +	max6917_read_alarm (struct device *dev, struct rtc_wkalrm *t)
> +	{
> +	struct i2c_client *client = to_i2c_client (dev);
> +	struct max6917 *max6917 = i2c_get_clientdata (client);
> +	int ret;
> +
> +	if (!test_bit (HAS_ALARM, &max6917->flags))
> +		return -EINVAL;
> +
> +	/* read all ALARM1, ALARM2, and status registers at once */
> +	ret = max6917->read_block_data (client,
> +					MAX6917_REG_ALARM, 9, max6917->regs);
> +	if (ret != 9)
> +		{
> +			dev_err (dev, " error %d\n", "alarm read", ret);
> +			return -EIO;
> +		}
> +
> +	dev_dbg (dev, "%4ph, %3ph, %2ph\n", "alarm read",
> +			&max6917->regs[0], &max6917->regs[4], &max6917->regs[7]);
> +
> +	/*
> +		* report alarm time (ALARM1); assume 24 hour and day-of-month modes,
> +		* and that all four fields are checked matches
> +		*/
> +	t->time.tm_sec = bcd2bin (max6917->regs[0] & 0x7f);
> +	t->time.tm_min = bcd2bin (max6917->regs[1] & 0x7f);
> +	t->time.tm_hour = bcd2bin (max6917->regs[2] & 0x3f);
> +	t->time.tm_mday = bcd2bin (max6917->regs[3] & 0x3f);
> +
> +	dev_dbg (dev, " %s secs=%d, mins=%d, "
> +			"hours=%d, mday=%d, enabled=%d, pending=%d\n",
> +			"alarm read", t->time.tm_sec, t->time.tm_min,
> +			t->time.tm_hour, t->time.tm_mday);
> +
> +	return 0;
> +	}
> +
> +	static int
> +	max6917_set_alarm (struct device *dev, struct rtc_wkalrm *t)
> +	{
> +	struct i2c_client *client = to_i2c_client (dev);
> +	struct max6917 *max6917 = i2c_get_clientdata (client);
> +	unsigned char *buf = max6917->regs;
> +	u8 control, status;
> +	int ret;
> +
> +	if (!test_bit (HAS_ALARM, &max6917->flags))
> +		return -EINVAL;
> +
> +	dev_dbg (dev, " %s secs=%d, mins=%d, "
> +			"hours=%d, mday=%d, enabled=%d, pending=%d\n",
> +			"alarm set", t->time.tm_sec, t->time.tm_min,
> +			t->time.tm_hour, t->time.tm_mday);
> +
> +	/* read current status of both alarms and the chip */
> +	ret = max6917->read_block_data (client, MAX6917_REG_ALARM, 9, buf);
> +	if (ret != 9)
> +		{
> +			dev_err (dev, "%s error %d\n", "alarm write", ret);
> +			return -EIO;
> +		}
> +	control = max6917->regs[7];
> +	status = max6917->regs[8];
> +
> +	dev_dbg (dev, "%s: %4ph, %3ph, %02x %02x\n", "alarm set (old status)",
> +			&max6917->regs[0], &max6917->regs[4], control, status);
> +
> +	/* set ALARM1, using 24 hour and day-of-month modes */
> +	buf[0] = bin2bcd (t->time.tm_sec);
> +	buf[1] = bin2bcd (t->time.tm_min);
> +	buf[2] = bin2bcd (t->time.tm_hour);
> +	buf[3] = bin2bcd (t->time.tm_mday);
> +	buf[4] = 0;
> +	buf[5] = 0;
> +	buf[6] = 0;
> +
> +	ret = max6917->write_block_data (client, MAX6917_REG_ALARM, 9, buf);
> +	if (ret < 0)
> +		{
> +			dev_err (dev, "can't set alarm time\n");
> +			return ret;
> +		}
> +	return 0;
> +	}
> +
> +	static ssize_t
> +	max6917_nvram_read (struct file *filp, struct kobject *kobj,
> +				struct bin_attribute *attr,
> +				char *buf, loff_t off, size_t count)
> +	{
> +	struct i2c_client *client;
> +	struct max6917 *max6917;
> +	int result;
> +
> +	client = kobj_to_i2c_client (kobj);
> +	max6917 = i2c_get_clientdata (client);
> +
> +	result = max6917->read_block_data (client, max6917->nvram_offset + off,
> +						count, buf);
> +	if (result < 0)
> +		dev_err (&client->dev, "%s error %d\n", "nvram read", result);
> +	return result;
> +	}
> +
> +	static ssize_t
> +	max6917_nvram_write (struct file *filp, struct kobject *kobj,
> +				struct bin_attribute *attr,
> +				char *buf, loff_t off, size_t count)
> +	{
> +	struct i2c_client *client;
> +	struct max6917 *max6917;
> +	int result;
> +
> +	client = kobj_to_i2c_client (kobj);
> +	max6917 = i2c_get_clientdata (client);
> +
> +	result = max6917->write_block_data (client, max6917->nvram_offset + off,
> +						count, buf);
> +	if (result < 0)
> +		{
> +			dev_err (&client->dev, "%s error %d\n", "nvram write", result);
> +			return result;
> +		}
> +	return count;
> +	}
> +
> +	static const struct rtc_class_ops max6917_rtc_ops = {
> +	.read_time = max6917_rtc_read_time,
> +	.set_time = max6917_rtc_set_time,
> +	.read_alarm = max6917_read_alarm,
> +	.set_alarm = max6917_set_alarm,
> +	};
> +
> +	static int
> +	max6917_probe (struct i2c_client *client, const struct i2c_device_id *id)
> +	{
> +	struct rtc_device *rtc;
> +
> +	if (!i2c_check_functionality (client->adapter, I2C_FUNC_I2C))
> +		return -ENODEV;
> +
> +	rtc = devm_rtc_device_register (&client->dev, max6917_driver.driver.name,
> +					&max6917_rtc_ops, THIS_MODULE);
> +	if (IS_ERR (rtc))
> +		return PTR_ERR (rtc);
> +
> +	i2c_set_clientdata (client, rtc);
> +
> +	return 0;
> +	}
> +
> +	static struct i2c_device_id max6917_id[] = {
> +	{"max6917", 0},
> +	{}
> +	};
> +
> +	MODULE_DEVICE_TABLE (i2c, max6917_id);
> +
> +	static struct i2c_driver max6917_driver = {
> +	.driver = {
> +			.name = "rtc-max6917",
> +			},
> +	.probe = max6917_probe,
> +	.id_table = max6917_id,
> +	};
> +
> +	module_i2c_driver (max6917_driver);
> +
> +	MODULE_DESCRIPTION ("Maxim MAX6917 RTC driver");
> +	MODULE_AUTHOR ("Venkat Prashanth B U");
> +	MODULE_LICENSE ("GPL");
> -- 
> 1.9.2
> 
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-- 
Alexandre Belloni, Free Electrons
Embedded Linux and Kernel engineering
http://free-electrons.com

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