diff mbox

[PATCHv4] rtc: Add support for Intersil ISL12057 I2C RTC chip

Message ID 1dec5992db795b61e91e0abf910dee7fce322ccc.1387227955.git.arno@natisbad.org
State Superseded, archived
Headers show

Commit Message

Arnaud Ebalard Dec. 16, 2013, 9:17 p.m. UTC
Intersil ISL12057 I2C RTC chip also supports two alarms. This patch
only adds support for basic RTC functionalities (i.e. getting and
setting time). Tests have been performed on NETGEAR ReadyNAS 102 w/
startup/shutdown scripts, hwclock, ntpdate and openntpd.

Signed-off-by: Arnaud Ebalard <arno@natisbad.org>
---

In order to get at least some initial support for the chip available in
mainline kernel (v3.14 will have three users waiting for it: ReadyNAS
102, 104 and 2120), I decided to temporarily remove the alarm and IRQ
related code I pushed earlier (see [1] below). If possible, I'd like to
iterate on this before Christmas in order not to miss ARM submission
cutoff (around -rc5) to push the .dts changes (once the driver is queued
for 3.14).

I will submit a patch later to add back Alarm/IRQ support once I get
some understanding of how to correctly handle my use case in current
RTC subsystem logic.

Comments welcome!

Cheers,

a+

[1]: http://thread.gmane.org/gmane.linux.drivers.devicetree/46581

Changes since previous v3 (comments from Guenter Roeck):
 - use BIT() instead of (1<<X)
 - use dev_set_drvdata()/dev_get_drvdata() to simplify access to 'data'
 - removed two (now) useless fields in private 'data' structure
 - now use dev instead of &client->dev

Changes since previous v2 (Comments from Mark Brown):
 - converted to regmap

Changes since previous v1 (Comments from Mark Rutland):
 - fixed return values for isl12057_i2c_{read,set}_regs()
 - checked associated return paths

Changes since previous v0:
 - removed alarm and IRQ related code
 - Switched to isl for intersil (no existing driver has any reference
   to isil, even though this would be the recommended choice)
 - Added intersil info in vendor-prefixes.txt file
 - Added entry for ISL 12057 in I2C trivial-devices.txt file
 - Added mutex protection for non atomic read/write


 .../devicetree/bindings/i2c/trivial-devices.txt    |   1 +
 .../devicetree/bindings/vendor-prefixes.txt        |   1 +
 drivers/rtc/Kconfig                                |  11 +
 drivers/rtc/Makefile                               |   1 +
 drivers/rtc/rtc-isl12057.c                         | 358 +++++++++++++++++++++
 5 files changed, 372 insertions(+)
 create mode 100644 drivers/rtc/rtc-isl12057.c

Comments

Guenter Roeck Dec. 16, 2013, 9:37 p.m. UTC | #1
On Mon, Dec 16, 2013 at 10:17:47PM +0100, Arnaud Ebalard wrote:
> 
> Intersil ISL12057 I2C RTC chip also supports two alarms. This patch
> only adds support for basic RTC functionalities (i.e. getting and
> setting time). Tests have been performed on NETGEAR ReadyNAS 102 w/
> startup/shutdown scripts, hwclock, ntpdate and openntpd.
> 
> Signed-off-by: Arnaud Ebalard <arno@natisbad.org>

Here is a snippet from the saved patch:

 obj-$(CONFIG_RTC_DRV_IMXDI)    +=3D rtc-imxdi.o
 obj-$(CONFIG_RTC_DRV_ISL1208)  +=3D rtc-isl1208.o
 obj-$(CONFIG_RTC_DRV_ISL12022) +=3D rtc-isl12022.o
+obj-$(CONFIG_RTC_DRV_ISL12057)  +=3D rtc-isl12057.o
 obj-$(CONFIG_RTC_DRV_JZ4740)   +=3D rtc-jz4740.o
 obj-$(CONFIG_RTC_DRV_LP8788)   +=3D rtc-lp8788.o
 obj-$(CONFIG_RTC_DRV_LPC32XX)  +=3D rtc-lpc32xx.o

Something is adding those '3D' after each '=' into the patch.

On a side note, even though it is hard to see, it seems you use two spaces
instead of a tab above, and that you do the same with other defines (unless the
mailer replaced tabs with spaces).

In general, the widely used form for defines is

#define<space>MY_DEFINE<tab>definition<tab>/* this is a comment */

Also, I think

+static struct i2c_driver isl12057_driver;

is unnecessary. But I'd really like to have a closer look again after you fixed
the =3D issue ...

Thanks,
Guenter
--
To unsubscribe from this list: send the line "unsubscribe devicetree" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Guenter Roeck Dec. 16, 2013, 10:18 p.m. UTC | #2
On Mon, Dec 16, 2013 at 10:17:47PM +0100, Arnaud Ebalard wrote:
> 
> Intersil ISL12057 I2C RTC chip also supports two alarms. This patch
> only adds support for basic RTC functionalities (i.e. getting and
> setting time). Tests have been performed on NETGEAR ReadyNAS 102 w/
> startup/shutdown scripts, hwclock, ntpdate and openntpd.
> 
> Signed-off-by: Arnaud Ebalard <arno@natisbad.org>

Weird; I saved the patch again and the '=3D' is gone. Maybe it was PBKC.
Comments inline.

> ---
> 
> In order to get at least some initial support for the chip available in
> mainline kernel (v3.14 will have three users waiting for it: ReadyNAS
> 102, 104 and 2120), I decided to temporarily remove the alarm and IRQ
> related code I pushed earlier (see [1] below). If possible, I'd like to
> iterate on this before Christmas in order not to miss ARM submission
> cutoff (around -rc5) to push the .dts changes (once the driver is queued
> for 3.14).
> 
> I will submit a patch later to add back Alarm/IRQ support once I get
> some understanding of how to correctly handle my use case in current
> RTC subsystem logic.
> 
> Comments welcome!
> 
> Cheers,
> 
> a+
> 
> [1]: http://thread.gmane.org/gmane.linux.drivers.devicetree/46581
> 
> Changes since previous v3 (comments from Guenter Roeck):
>  - use BIT() instead of (1<<X)
>  - use dev_set_drvdata()/dev_get_drvdata() to simplify access to 'data'
>  - removed two (now) useless fields in private 'data' structure
>  - now use dev instead of &client->dev
> 
> Changes since previous v2 (Comments from Mark Brown):
>  - converted to regmap
> 
> Changes since previous v1 (Comments from Mark Rutland):
>  - fixed return values for isl12057_i2c_{read,set}_regs()
>  - checked associated return paths
> 
> Changes since previous v0:
>  - removed alarm and IRQ related code
>  - Switched to isl for intersil (no existing driver has any reference
>    to isil, even though this would be the recommended choice)
>  - Added intersil info in vendor-prefixes.txt file
>  - Added entry for ISL 12057 in I2C trivial-devices.txt file
>  - Added mutex protection for non atomic read/write
> 
> 
>  .../devicetree/bindings/i2c/trivial-devices.txt    |   1 +
>  .../devicetree/bindings/vendor-prefixes.txt        |   1 +
>  drivers/rtc/Kconfig                                |  11 +
>  drivers/rtc/Makefile                               |   1 +
>  drivers/rtc/rtc-isl12057.c                         | 358 +++++++++++++++++++++
>  5 files changed, 372 insertions(+)
>  create mode 100644 drivers/rtc/rtc-isl12057.c
> 
> diff --git a/Documentation/devicetree/bindings/i2c/trivial-devices.txt b/Documentation/devicetree/bindings/i2c/trivial-devices.txt
> index b1cb341..cdf1430 100644
> --- a/Documentation/devicetree/bindings/i2c/trivial-devices.txt
> +++ b/Documentation/devicetree/bindings/i2c/trivial-devices.txt
> @@ -39,6 +39,7 @@ fsl,sgtl5000		SGTL5000: Ultra Low-Power Audio Codec
>  gmt,g751		G751: Digital Temperature Sensor and Thermal Watchdog with Two-Wire Interface
>  infineon,slb9635tt	Infineon SLB9635 (Soft-) I2C TPM (old protocol, max 100khz)
>  infineon,slb9645tt	Infineon SLB9645 I2C TPM (new protocol, max 400khz)
> +isl,isl12057		Intersil ISL12057 I2C RTC Chip
>  maxim,ds1050		5 Bit Programmable, Pulse-Width Modulator
>  maxim,max1237		Low-Power, 4-/12-Channel, 2-Wire Serial, 12-Bit ADCs
>  maxim,max6625		9-Bit/12-Bit Temperature Sensors with I²C-Compatible Serial Interface
> diff --git a/Documentation/devicetree/bindings/vendor-prefixes.txt b/Documentation/devicetree/bindings/vendor-prefixes.txt
> index edbb8d8..ed0f63f 100644
> --- a/Documentation/devicetree/bindings/vendor-prefixes.txt
> +++ b/Documentation/devicetree/bindings/vendor-prefixes.txt
> @@ -39,6 +39,7 @@ ibm	International Business Machines (IBM)
>  idt	Integrated Device Technologies, Inc.
>  img	Imagination Technologies Ltd.
>  intercontrol	Inter Control Group
> +isl	Intersil
>  lg	LG Corporation
>  linux	Linux-specific binding
>  lsi	LSI Corp. (LSI Logic)
> diff --git a/drivers/rtc/Kconfig b/drivers/rtc/Kconfig
> index 0077302..9608210 100644
> --- a/drivers/rtc/Kconfig
> +++ b/drivers/rtc/Kconfig
> @@ -304,6 +304,17 @@ config RTC_DRV_ISL12022
>  	  This driver can also be built as a module. If so, the module
>  	  will be called rtc-isl12022.
>  
> +config RTC_DRV_ISL12057
> +       depends on I2C
> +       select REGMAP_I2C
> +       tristate "Intersil ISL12057"
> +       help
> +	  If you say yes here you get support for the Intersil ISL12057
> +	  I2C RTC chip.
> +
> +	  This driver can also be built as a module. If so, the module
> +	  will be called rtc-isl12057.
> +
>  config RTC_DRV_X1205
>  	tristate "Xicor/Intersil X1205"
>  	help
> diff --git a/drivers/rtc/Makefile b/drivers/rtc/Makefile
> index 27b4bd8..6cd50e5 100644
> --- a/drivers/rtc/Makefile
> +++ b/drivers/rtc/Makefile
> @@ -58,6 +58,7 @@ obj-$(CONFIG_RTC_DRV_HID_SENSOR_TIME) += rtc-hid-sensor-time.o
>  obj-$(CONFIG_RTC_DRV_IMXDI)	+= rtc-imxdi.o
>  obj-$(CONFIG_RTC_DRV_ISL1208)	+= rtc-isl1208.o
>  obj-$(CONFIG_RTC_DRV_ISL12022)	+= rtc-isl12022.o
> +obj-$(CONFIG_RTC_DRV_ISL12057)  += rtc-isl12057.o

Please use tab after the define.

>  obj-$(CONFIG_RTC_DRV_JZ4740)	+= rtc-jz4740.o
>  obj-$(CONFIG_RTC_DRV_LP8788)	+= rtc-lp8788.o
>  obj-$(CONFIG_RTC_DRV_LPC32XX)	+= rtc-lpc32xx.o
> diff --git a/drivers/rtc/rtc-isl12057.c b/drivers/rtc/rtc-isl12057.c
> new file mode 100644
> index 0000000..8a1851e
> --- /dev/null
> +++ b/drivers/rtc/rtc-isl12057.c
> @@ -0,0 +1,358 @@
> +/*
> + * rtc-isl12057 - Driver for Intersil ISL12057 I2C Real Time Clock
> + *
> + * Copyright (C) 2013, Arnaud EBALARD <arno@natisbad.org>
> + *
> + * This work is largely based on Intersil ISL1208 driver developed by
> + * Hebert Valerio Riedel <hvr@gnu.org>.
> + *
> + * Detailed datasheet on which this development is based is available here:
> + *
> + *  http://natisbad.org/NAS2/refs/ISL12057.pdf
> + *
> + * This program is free software; you can redistribute it and/or modify
> + * it under the terms of the GNU General Public License as published by
> + * the Free Software Foundation; either version 2 of the License, or
> + * (at your option) any later version.
> + *
> + * This program is distributed in the hope that it will be useful,
> + * but WITHOUT ANY WARRANTY; without even the implied warranty of
> + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
> + * GNU General Public License for more details.
> + *
> + * You should have received a copy of the GNU General Public License
> + * along with this program; if not, write to the Free Software
> + * Foundation.

checkpatch complains about the above paragraph. I would suggest to remove it.

> + */
> +
> +#include <linux/module.h>
> +#include <linux/mutex.h>
> +#include <linux/rtc.h>
> +#include <linux/i2c.h>
> +#include <linux/bcd.h>
> +#include <linux/rtc.h>
> +#include <linux/of.h>
> +#include <linux/of_device.h>
> +#include <linux/regmap.h>
> +
> +#define DRV_NAME "rtc-isl12057"
> +
> +/* RTC section */
> +#define ISL12057_REG_RTC_SC     0x00 /* Seconds */
> +#define ISL12057_REG_RTC_MN     0x01 /* Minutes */
> +#define ISL12057_REG_RTC_HR     0x02 /* Hours */
> +#define ISL12057_REG_RTC_HR_PM  BIT(5) /* AM/PM bit in 12h format */
> +#define ISL12057_REG_RTC_HR_MIL BIT(6) /* 24h/12h format */
> +#define ISL12057_REG_RTC_DW     0x03 /* Day of the Week */
> +#define ISL12057_REG_RTC_DT     0x04 /* Date */
> +#define ISL12057_REG_RTC_MO     0x05 /* Month */
> +#define ISL12057_REG_RTC_YR     0x06 /* Year */
> +#define ISL12057_RTC_SEC_LEN    7
> +
> +/* Alarm 1 section */
> +#define ISL12057_REG_A1_SC      0x07 /* Alarm 1 Seconds */
> +#define ISL12057_REG_A1_MN      0x08 /* Alarm 1 Minutes */
> +#define ISL12057_REG_A1_HR      0x09 /* Alarm 1 Hours */
> +#define ISL12057_REG_A1_HR_PM   BIT(5) /* AM/PM bit in 12h format */
> +#define ISL12057_REG_A1_HR_MIL  BIT(6) /* 24h/12h format */
> +#define ISL12057_REG_A1_DWDT    0x0A /* Alarm 1 Date / Day of the week */
> +#define ISL12057_REG_A1_DWDT_B  BIT(6) /* DW / DT selection bit */
> +#define ISL12057_A1_SEC_LEN     4
> +
> +/* Alarm 2 section */
> +#define ISL12057_REG_A2_MN      0x0B /* Alarm 2 Minutes */
> +#define ISL12057_REG_A2_HR      0x0C /* Alarm 2 Hours */
> +#define ISL12057_REG_A2_DWDT    0x0D /* Alarm 2 Date / Day of the week */
> +#define ISL12057_A2_SEC_LEN     3
> +
> +/* Control/Status registers */
> +#define ISL12057_REG_INT        0x0E
> +#define ISL12057_REG_INT_A1IE   BIT(0) /* Alarm 1 interrupt enable bit */
> +#define ISL12057_REG_INT_A2IE   BIT(1) /* Alarm 2 interrupt enable bit */
> +#define ISL12057_REG_INT_INTCN  BIT(2) /* Interrupt control enable bit */
> +#define ISL12057_REG_INT_RS1    BIT(3) /* Freq out control bit 1 */
> +#define ISL12057_REG_INT_RS2    BIT(4) /* Freq out control bit 2 */
> +#define ISL12057_REG_INT_EOSC   BIT(7) /* Oscillator enable bit */
> +
> +#define ISL12057_REG_SR         0x0F
> +#define ISL12057_REG_SR_A1F     BIT(0) /* Alarm 1 interrupt bit */
> +#define ISL12057_REG_SR_A2F     BIT(1) /* Alarm 2 interrupt bit */
> +#define ISL12057_REG_SR_OSF     BIT(7) /* Oscillator failure bit */
> +
> +/* Register memory map length */
> +#define ISL12057_MEM_MAP_LEN    0x10
> +

Please use tab after the define (and if possible before the comments).

Also, many of the above defines are unused (especially the alarm defines).
Will those ever be necessary/used ? Otherwise I would suggest to remove
the unused defines.

> +static struct i2c_driver isl12057_driver;
> +

Unnecessary.

> +struct isl12057_rtc_data {
> +	struct rtc_device *rtc;
> +	struct regmap *regmap;
> +	struct mutex lock;
> +};
> +
> +static void isl12057_rtc_regs_to_tm(struct rtc_time *tm, u8 *regs)
> +{
> +	tm->tm_sec = bcd2bin(regs[ISL12057_REG_RTC_SC]);
> +	tm->tm_min = bcd2bin(regs[ISL12057_REG_RTC_MN]);
> +
> +	if (regs[ISL12057_REG_RTC_HR] & ISL12057_REG_RTC_HR_MIL) { /* AM/PM */
> +		tm->tm_hour = bcd2bin(regs[ISL12057_REG_RTC_HR] & 0x0f);
> +		if (regs[ISL12057_REG_RTC_HR] & ISL12057_REG_RTC_HR_PM)
> +			tm->tm_hour += 12;
> +	} else {                                            /* 24 hour mode */
> +		tm->tm_hour = bcd2bin(regs[ISL12057_REG_RTC_HR] & 0x3f);
> +	}
> +
> +	tm->tm_mday = bcd2bin(regs[ISL12057_REG_RTC_DT]);
> +	tm->tm_wday = bcd2bin(regs[ISL12057_REG_RTC_DW]) - 1; /* starts at 1 */
> +	tm->tm_mon  = bcd2bin(regs[ISL12057_REG_RTC_MO]) - 1; /* starts at 1 */
> +	tm->tm_year = bcd2bin(regs[ISL12057_REG_RTC_YR]) + 100;
> +}
> +
> +static int isl12057_rtc_tm_to_regs(u8 *regs, struct rtc_time *tm)
> +{
> +	/*
> +	 * The clock has an 8 bit wide bcd-coded register for the year.
> +	 * tm_year is an offset from 1900 and we are interested in the
> +	 * 2000-2099 range, so any value less than 100 is invalid.
> +	 */
> +	if (tm->tm_year < 100)
> +		return -EINVAL;
> +
> +	regs[ISL12057_REG_RTC_SC] = bin2bcd(tm->tm_sec);
> +	regs[ISL12057_REG_RTC_MN] = bin2bcd(tm->tm_min);
> +	regs[ISL12057_REG_RTC_HR] = bin2bcd(tm->tm_hour); /* 24-hour format */
> +	regs[ISL12057_REG_RTC_DT] = bin2bcd(tm->tm_mday);
> +	regs[ISL12057_REG_RTC_MO] = bin2bcd(tm->tm_mon + 1);
> +	regs[ISL12057_REG_RTC_YR] = bin2bcd(tm->tm_year - 100);
> +	regs[ISL12057_REG_RTC_DW] = bin2bcd(tm->tm_wday + 1);
> +
> +	return 0;
> +}
> +
> +/*
> + * Try and match register bits w/ fixed null values to see whether we
> + * are dealing with an ISL12057.
> + */

For isl12057_check_rtc_status you added a comment explaining why a lock is not
needed. It would be useful to have that same comment here as well.

> +static int isl12057_i2c_validate_chip(struct regmap *regmap)
> +{
> +	u8 regs[ISL12057_MEM_MAP_LEN];
> +	u8 mask[ISL12057_MEM_MAP_LEN] = { 0x80, 0x80, 0x80, 0xf8,
> +					  0xc0, 0x60, 0x00, 0x00,
> +					  0x00, 0x00, 0x00, 0x00,
> +					  0x00, 0x00, 0x60, 0x7c };
> +	int ret, i;
> +
> +	ret = regmap_bulk_read(regmap, 0, regs, ISL12057_MEM_MAP_LEN);
> +	if (ret)
> +		return ret;
> +
> +	for (i = 0; i < ISL12057_MEM_MAP_LEN; ++i) {
> +		if (regs[i] & mask[i])	/* check if bits are cleared */
> +			return -ENODEV;
> +	}
> +
> +	return 0;
> +}
> +
> +static int isl12057_rtc_read_time(struct device *dev, struct rtc_time *tm)
> +{
> +	struct isl12057_rtc_data *data = dev_get_drvdata(dev);
> +	u8 regs[ISL12057_RTC_SEC_LEN];
> +	int ret;
> +
> +	mutex_lock(&data->lock);
> +	ret = regmap_bulk_read(data->regmap, ISL12057_REG_RTC_SC, regs,
> +			       ISL12057_RTC_SEC_LEN);
> +	mutex_unlock(&data->lock);
> +
> +	if (ret) {
> +		dev_err(dev, "%s: RTC read failed\n", __func__);
> +		return ret;
> +	}
> +
> +	isl12057_rtc_regs_to_tm(tm, regs);
> +
> +	return rtc_valid_tm(tm);
> +}
> +
> +static int isl12057_rtc_set_time(struct device *dev, struct rtc_time *tm)
> +{
> +	struct isl12057_rtc_data *data = dev_get_drvdata(dev);
> +	u8 regs[ISL12057_RTC_SEC_LEN];
> +	int ret;
> +
> +	ret = isl12057_rtc_tm_to_regs(regs, tm);
> +	if (ret)
> +		return ret;
> +
> +	mutex_lock(&data->lock);
> +	ret = regmap_bulk_write(data->regmap, ISL12057_REG_RTC_SC, regs,
> +				ISL12057_RTC_SEC_LEN);
> +	mutex_unlock(&data->lock);
> +
> +	if (ret)
> +		dev_err(dev, "%s: RTC write failed\n", __func__);
> +
> +	return ret;
> +}
> +
> +static int isl12057_rtc_proc(struct device *dev, struct seq_file *seq)
> +{
> +	struct isl12057_rtc_data *data = dev_get_drvdata(dev);
> +	int reg, ret;
> +
> +	mutex_lock(&data->lock);
> +
> +	/* Status register */
> +	ret = regmap_read(data->regmap, ISL12057_REG_SR, &reg);
> +	if (ret) {
> +		dev_err(dev, "%s: reading SR failed\n", __func__);
> +		goto out;
> +	}
> +
> +	seq_printf(seq, "status_reg\t:%s%s%s (0x%.2x)\n",
> +		   (reg & ISL12057_REG_SR_OSF) ? " OSF" : "",
> +		   (reg & ISL12057_REG_SR_A1F) ? " A1F" : "",
> +		   (reg & ISL12057_REG_SR_A2F) ? " A2F" : "", reg);
> +
> +	/* Control register */
> +	ret = regmap_read(data->regmap, ISL12057_REG_INT, &reg);
> +	if (ret) {
> +		dev_err(dev, "%s: reading INT failed\n", __func__);
> +		goto out;
> +	}
> +
> +	seq_printf(seq, "control_reg\t:%s%s%s%s%s%s (0x%.2x)\n",
> +		   (reg & ISL12057_REG_INT_A1IE) ?  " A1IE"  : "",
> +		   (reg & ISL12057_REG_INT_A2IE) ?  " A2IE"  : "",
> +		   (reg & ISL12057_REG_INT_INTCN) ? " INTCN" : "",
> +		   (reg & ISL12057_REG_INT_RS1) ?   " RS1"   : "",
> +		   (reg & ISL12057_REG_INT_RS2) ?   " RS2"   : "",
> +		   (reg & ISL12057_REG_INT_EOSC) ?  " EOSC"  : "", reg);
> +
> + out:
> +	mutex_unlock(&data->lock);
> +
> +	return ret;
> +}
> +
> +/*
> + * Check current RTC status and enable/disable what needs to be. Return 0 if
> + * everything went ok and a negative value upon error. Note: this function
> + * is called early during init and hence does need mutex protection.
> + */
> +static int isl12057_check_rtc_status(struct device *dev, struct regmap *regmap)
> +{
> +	int ret;
> +
> +	/* Enable oscillator if not already running */
> +	ret = regmap_update_bits(regmap, ISL12057_REG_INT,
> +				 ISL12057_REG_INT_EOSC, 0);
> +	if (ret < 0) {
> +		dev_err(dev, "Enable to enable oscillator\n");

	s/Enable/Unable/

or at least I think so.

> +		return ret;
> +	}
> +
> +	/* Clear oscillator failure bit if needed */
> +	ret = regmap_update_bits(regmap, ISL12057_REG_SR,
> +				 ISL12057_REG_SR_OSF, 0);
> +	if (ret < 0) {
> +		dev_err(dev, "Enable to clear oscillator failure bit\n");

Unable ?

> +		return ret;
> +	}
> +
> +	/* Clear alarm bit if needed */
> +	ret = regmap_update_bits(regmap, ISL12057_REG_SR,
> +				 ISL12057_REG_SR_A1F, 0);
> +	if (ret < 0) {
> +		dev_err(dev, "Enable to clear alarm bit\n");

Unable ?

> +		return ret;
> +	}
> +
> +	return 0;
> +}
> +
> +static const struct rtc_class_ops rtc_ops = {
> +	.read_time = isl12057_rtc_read_time,
> +	.set_time = isl12057_rtc_set_time,
> +	.proc = isl12057_rtc_proc,
> +};
> +
> +static struct regmap_config isl12057_rtc_regmap_config = {
> +	.reg_bits = 8,
> +	.val_bits = 8,
> +};
> +
> +static int isl12057_probe(struct i2c_client *client,
> +			  const struct i2c_device_id *id)
> +{
> +	struct device *dev = &client->dev;
> +	struct isl12057_rtc_data *data;
> +	struct rtc_device *rtc;
> +	struct regmap *regmap;
> +	int ret;
> +
> +	if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C |
> +				     I2C_FUNC_SMBUS_BYTE_DATA |
> +				     I2C_FUNC_SMBUS_I2C_BLOCK))
> +		return -ENODEV;
> +
> +	regmap = devm_regmap_init_i2c(client, &isl12057_rtc_regmap_config);
> +	if (IS_ERR(regmap)) {
> +		ret = PTR_ERR(regmap);
> +		dev_err(dev, "regmap allocation failed: %d\n", ret);
> +		return ret;
> +	}
> +
> +	ret = isl12057_i2c_validate_chip(regmap);
> +	if (ret)
> +		return ret;
> +
> +	ret = isl12057_check_rtc_status(dev, regmap);
> +	if (ret)
> +		return ret;
> +
> +	data = devm_kzalloc(dev, sizeof(*data), GFP_KERNEL);
> +	if (!data)
> +		return -ENOMEM;
> +
> +	mutex_init(&data->lock);
> +	data->regmap = regmap;
> +	dev_set_drvdata(dev, data);
> +
> +	rtc = devm_rtc_device_register(dev, DRV_NAME, &rtc_ops, THIS_MODULE);
> +	if (IS_ERR(rtc))
> +		return PTR_ERR(rtc);
> +	data->rtc = rtc;

data->rtc still seems to be unused.

> +
> +	return 0;
> +}
> +
> +#ifdef CONFIG_OF
> +static struct of_device_id isl12057_dt_match[] = {
> +	{ .compatible = "isl,isl12057" },
> +	{ },
> +};
> +#endif
> +
> +static const struct i2c_device_id isl12057_id[] = {
> +	{ "isl12057", 0 },
> +	{ }
> +};
> +MODULE_DEVICE_TABLE(i2c, isl12057_id);
> +
> +static struct i2c_driver isl12057_driver = {
> +	.driver = {
> +		.name = DRV_NAME,
> +		.owner = THIS_MODULE,
> +		.of_match_table = of_match_ptr(isl12057_dt_match),
> +	},
> +	.probe	  = isl12057_probe,
> +	.id_table = isl12057_id,
> +};
> +module_i2c_driver(isl12057_driver);
> +
> +MODULE_AUTHOR("Arnaud EBALARD <arno@natisbad.org>");
> +MODULE_DESCRIPTION("Intersil ISL12057 RTC driver");
> +MODULE_LICENSE("GPL");
> -- 
> 1.8.4.4
> 
> 
--
To unsubscribe from this list: send the line "unsubscribe devicetree" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Arnaud Ebalard Dec. 16, 2013, 10:24 p.m. UTC | #3
Hi Guenter,

Guenter Roeck <linux@roeck-us.net> writes:

> On Mon, Dec 16, 2013 at 10:17:47PM +0100, Arnaud Ebalard wrote:
>> 
>> Intersil ISL12057 I2C RTC chip also supports two alarms. This patch
>> only adds support for basic RTC functionalities (i.e. getting and
>> setting time). Tests have been performed on NETGEAR ReadyNAS 102 w/
>> startup/shutdown scripts, hwclock, ntpdate and openntpd.
>> 
>> Signed-off-by: Arnaud Ebalard <arno@natisbad.org>
>
> Here is a snippet from the saved patch:
>
>  obj-$(CONFIG_RTC_DRV_IMXDI)    +=3D rtc-imxdi.o
>  obj-$(CONFIG_RTC_DRV_ISL1208)  +=3D rtc-isl1208.o
>  obj-$(CONFIG_RTC_DRV_ISL12022) +=3D rtc-isl12022.o
> +obj-$(CONFIG_RTC_DRV_ISL12057)  +=3D rtc-isl12057.o
>  obj-$(CONFIG_RTC_DRV_JZ4740)   +=3D rtc-jz4740.o
>  obj-$(CONFIG_RTC_DRV_LP8788)   +=3D rtc-lp8788.o
>  obj-$(CONFIG_RTC_DRV_LPC32XX)  +=3D rtc-lpc32xx.o
>
> Something is adding those '3D' after each '=' into the patch.

Well, I simply use git-imap-send to send the patch to my IMAP draft
folder and then sent it from my mailer (Gnus/5.13 for Emacs/24.3).

What is very weird is that if I simply save the mail I received from
LAKML (I am registered to LAKML which I have put in Cc:), checkptach
gives me the following (my checkpatch.pl is the one in 3.13.0.rc4):

  $ ./scripts/checkpatch.pl /tmp/v4.patch ERROR: Do not include the
  paragraph about writing to the Free Software Foundation's mailing
  address from the sample GPL notice. The FSF has changed addresses in the
  past, and may do so again. Linux already includes a copy of the GPL. 
  #165: FILE: drivers/rtc/rtc-isl12057.c:23:
  + * You should have received a copy of the GNU General Public License$
  
  ERROR: Do not include the paragraph about writing to the Free Software
  Foundation's mailing address from the sample GPL notice. The FSF has
  changed addresses in the past, and may do so again. Linux already
  includes a copy of the GPL. 
  #166: FILE: drivers/rtc/rtc-isl12057.c:24:
  + * along with this program; if not, write to the Free Software$
  
  total: 2 errors, 0 warnings, 396 lines checked
  
  /tmp/v4.patch has style problems, please review.
  
  If any of these errors are false positives, please report
  them to the maintainer, see CHECKPATCH in MAINTAINERS.

Those false/positive are the only error checkptach reports on my side
for the patch. This is the same if I copy/paste the content of the
<pre></pre> with the patch in the following page:

 http://www.spinics.net/lists/arm-kernel/msg294759.html. 

I do not say you are wrong but I do not have a clue were the problem
may come from.


> On a side note, even though it is hard to see, it seems you use two
> spaces instead of a tab above, and that you do the same with other
> defines

That I can confirm.


> (unless the mailer replaced tabs with spaces).
>
> In general, the widely used form for defines is
>
> #define<space>MY_DEFINE<tab>definition<tab>/* this is a comment */

I have changed my .emacs config and will test its behavior.


> Also, I think
>
> +static struct i2c_driver isl12057_driver;
>
> is unnecessary

Right.

Cheers,

a+
--
To unsubscribe from this list: send the line "unsubscribe devicetree" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Arnaud Ebalard Dec. 16, 2013, 10:36 p.m. UTC | #4
Hi,

Guenter Roeck <linux@roeck-us.net> writes:

> On Mon, Dec 16, 2013 at 10:17:47PM +0100, Arnaud Ebalard wrote:
>> 
>> Intersil ISL12057 I2C RTC chip also supports two alarms. This patch
>> only adds support for basic RTC functionalities (i.e. getting and
>> setting time). Tests have been performed on NETGEAR ReadyNAS 102 w/
>> startup/shutdown scripts, hwclock, ntpdate and openntpd.
>> 
>> Signed-off-by: Arnaud Ebalard <arno@natisbad.org>
>
> Weird; I saved the patch again and the '=3D' is gone. Maybe it was PBKC.
> Comments inline.

no problem.

>> diff --git a/drivers/rtc/Makefile b/drivers/rtc/Makefile
>> index 27b4bd8..6cd50e5 100644
>> --- a/drivers/rtc/Makefile
>> +++ b/drivers/rtc/Makefile
>> @@ -58,6 +58,7 @@ obj-$(CONFIG_RTC_DRV_HID_SENSOR_TIME) += rtc-hid-sensor-time.o
>>  obj-$(CONFIG_RTC_DRV_IMXDI)	+= rtc-imxdi.o
>>  obj-$(CONFIG_RTC_DRV_ISL1208)	+= rtc-isl1208.o
>>  obj-$(CONFIG_RTC_DRV_ISL12022)	+= rtc-isl12022.o
>> +obj-$(CONFIG_RTC_DRV_ISL12057)  += rtc-isl12057.o
>
> Please use tab after the define.

Will fix that in next round.


>> + * This program is free software; you can redistribute it and/or modify
>> + * it under the terms of the GNU General Public License as published by
>> + * the Free Software Foundation; either version 2 of the License, or
>> + * (at your option) any later version.
>> + *
>> + * This program is distributed in the hope that it will be useful,
>> + * but WITHOUT ANY WARRANTY; without even the implied warranty of
>> + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
>> + * GNU General Public License for more details.
>> + *
>> + * You should have received a copy of the GNU General Public License
>> + * along with this program; if not, write to the Free Software
>> + * Foundation.
>
> checkpatch complains about the above paragraph. I would suggest to
> remove it.

Will make checkpacth happy.


>> +/* Control/Status registers */
>> +#define ISL12057_REG_INT        0x0E
>> +#define ISL12057_REG_INT_A1IE   BIT(0) /* Alarm 1 interrupt enable bit */
>> +#define ISL12057_REG_INT_A2IE   BIT(1) /* Alarm 2 interrupt enable bit */
>> +#define ISL12057_REG_INT_INTCN  BIT(2) /* Interrupt control enable bit */
>> +#define ISL12057_REG_INT_RS1    BIT(3) /* Freq out control bit 1 */
>> +#define ISL12057_REG_INT_RS2    BIT(4) /* Freq out control bit 2 */
>> +#define ISL12057_REG_INT_EOSC   BIT(7) /* Oscillator enable bit */
>> +
>> +#define ISL12057_REG_SR         0x0F
>> +#define ISL12057_REG_SR_A1F     BIT(0) /* Alarm 1 interrupt bit */
>> +#define ISL12057_REG_SR_A2F     BIT(1) /* Alarm 2 interrupt bit */
>> +#define ISL12057_REG_SR_OSF     BIT(7) /* Oscillator failure bit */
>> +
>> +/* Register memory map length */
>> +#define ISL12057_MEM_MAP_LEN    0x10
>> +
>
> Please use tab after the define (and if possible before the comments).

ok.


> Also, many of the above defines are unused (especially the alarm defines).
> Will those ever be necessary/used ? Otherwise I would suggest to remove
> the unused defines.

I think it makes sense to keep all the bits definitions instead of
providing some sparse info about used ones. Additionally, alarm bits
will be used as soon as I get some feedback on how to support my use
case: the interrupt line of the chip is not connected to the SoC but
some power component. This does not seem something common.


>
>> +static struct i2c_driver isl12057_driver;
>> +
>
> Unnecessary.

yep.


>> +/*
>> + * Try and match register bits w/ fixed null values to see whether we
>> + * are dealing with an ISL12057.
>> + */
>
> For isl12057_check_rtc_status you added a comment explaining why a lock is not
> needed. It would be useful to have that same comment here as well.

will add it.


>> +/*
>> + * Check current RTC status and enable/disable what needs to be. Return 0 if
>> + * everything went ok and a negative value upon error. Note: this function
>> + * is called early during init and hence does need mutex protection.
>> + */
>> +static int isl12057_check_rtc_status(struct device *dev, struct regmap *regmap)
>> +{
>> +	int ret;
>> +
>> +	/* Enable oscillator if not already running */
>> +	ret = regmap_update_bits(regmap, ISL12057_REG_INT,
>> +				 ISL12057_REG_INT_EOSC, 0);
>> +	if (ret < 0) {
>> +		dev_err(dev, "Enable to enable oscillator\n");
>
> 	s/Enable/Unable/
>
> or at least I think so.

yep.


>> +		return ret;
>> +	}
>> +
>> +	/* Clear oscillator failure bit if needed */
>> +	ret = regmap_update_bits(regmap, ISL12057_REG_SR,
>> +				 ISL12057_REG_SR_OSF, 0);
>> +	if (ret < 0) {
>> +		dev_err(dev, "Enable to clear oscillator failure bit\n");
>
> Unable ?
>
>
>> +		return ret;
>> +	}
>> +
>> +	/* Clear alarm bit if needed */
>> +	ret = regmap_update_bits(regmap, ISL12057_REG_SR,
>> +				 ISL12057_REG_SR_A1F, 0);
>> +	if (ret < 0) {
>> +		dev_err(dev, "Enable to clear alarm bit\n");
>
> Unable ?

Damned. That was a day w/o coffee, I guess.

>> +		return ret;
>> +	}
>> +
>> +	return 0;
>> +}
>> +
>> +static const struct rtc_class_ops rtc_ops = {
>> +	.read_time = isl12057_rtc_read_time,
>> +	.set_time = isl12057_rtc_set_time,
>> +	.proc = isl12057_rtc_proc,
>> +};
>> +
>> +static struct regmap_config isl12057_rtc_regmap_config = {
>> +	.reg_bits = 8,
>> +	.val_bits = 8,
>> +};
>> +
>> +static int isl12057_probe(struct i2c_client *client,
>> +			  const struct i2c_device_id *id)
>> +{
>> +	struct device *dev = &client->dev;
>> +	struct isl12057_rtc_data *data;
>> +	struct rtc_device *rtc;
>> +	struct regmap *regmap;
>> +	int ret;
>> +
>> +	if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C |
>> +				     I2C_FUNC_SMBUS_BYTE_DATA |
>> +				     I2C_FUNC_SMBUS_I2C_BLOCK))
>> +		return -ENODEV;
>> +
>> +	regmap = devm_regmap_init_i2c(client, &isl12057_rtc_regmap_config);
>> +	if (IS_ERR(regmap)) {
>> +		ret = PTR_ERR(regmap);
>> +		dev_err(dev, "regmap allocation failed: %d\n", ret);
>> +		return ret;
>> +	}
>> +
>> +	ret = isl12057_i2c_validate_chip(regmap);
>> +	if (ret)
>> +		return ret;
>> +
>> +	ret = isl12057_check_rtc_status(dev, regmap);
>> +	if (ret)
>> +		return ret;
>> +
>> +	data = devm_kzalloc(dev, sizeof(*data), GFP_KERNEL);
>> +	if (!data)
>> +		return -ENOMEM;
>> +
>> +	mutex_init(&data->lock);
>> +	data->regmap = regmap;
>> +	dev_set_drvdata(dev, data);
>> +
>> +	rtc = devm_rtc_device_register(dev, DRV_NAME, &rtc_ops, THIS_MODULE);
>> +	if (IS_ERR(rtc))
>> +		return PTR_ERR(rtc);
>> +	data->rtc = rtc;
>
> data->rtc still seems to be unused.

I *indeed* forgot to remove it.

Thanks for your time Guenter.

Cheers,

a+

--
To unsubscribe from this list: send the line "unsubscribe devicetree" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Guenter Roeck Dec. 16, 2013, 10:38 p.m. UTC | #5
On Mon, Dec 16, 2013 at 11:24:01PM +0100, Arnaud Ebalard wrote:
> Hi Guenter,
> 
> Guenter Roeck <linux@roeck-us.net> writes:
> 
> > On Mon, Dec 16, 2013 at 10:17:47PM +0100, Arnaud Ebalard wrote:
> >> 
> >> Intersil ISL12057 I2C RTC chip also supports two alarms. This patch
> >> only adds support for basic RTC functionalities (i.e. getting and
> >> setting time). Tests have been performed on NETGEAR ReadyNAS 102 w/
> >> startup/shutdown scripts, hwclock, ntpdate and openntpd.
> >> 
> >> Signed-off-by: Arnaud Ebalard <arno@natisbad.org>
> >
> > Here is a snippet from the saved patch:
> >
> >  obj-$(CONFIG_RTC_DRV_IMXDI)    +=3D rtc-imxdi.o
> >  obj-$(CONFIG_RTC_DRV_ISL1208)  +=3D rtc-isl1208.o
> >  obj-$(CONFIG_RTC_DRV_ISL12022) +=3D rtc-isl12022.o
> > +obj-$(CONFIG_RTC_DRV_ISL12057)  +=3D rtc-isl12057.o
> >  obj-$(CONFIG_RTC_DRV_JZ4740)   +=3D rtc-jz4740.o
> >  obj-$(CONFIG_RTC_DRV_LP8788)   +=3D rtc-lp8788.o
> >  obj-$(CONFIG_RTC_DRV_LPC32XX)  +=3D rtc-lpc32xx.o
> >
> > Something is adding those '3D' after each '=' into the patch.
> 
> Well, I simply use git-imap-send to send the patch to my IMAP draft
> folder and then sent it from my mailer (Gnus/5.13 for Emacs/24.3).
> 
> What is very weird is that if I simply save the mail I received from
> LAKML (I am registered to LAKML which I have put in Cc:), checkptach
> gives me the following (my checkpatch.pl is the one in 3.13.0.rc4):
> 
>   $ ./scripts/checkpatch.pl /tmp/v4.patch ERROR: Do not include the
>   paragraph about writing to the Free Software Foundation's mailing
>   address from the sample GPL notice. The FSF has changed addresses in the
>   past, and may do so again. Linux already includes a copy of the GPL. 
>   #165: FILE: drivers/rtc/rtc-isl12057.c:23:
>   + * You should have received a copy of the GNU General Public License$
>   
>   ERROR: Do not include the paragraph about writing to the Free Software
>   Foundation's mailing address from the sample GPL notice. The FSF has
>   changed addresses in the past, and may do so again. Linux already
>   includes a copy of the GPL. 
>   #166: FILE: drivers/rtc/rtc-isl12057.c:24:
>   + * along with this program; if not, write to the Free Software$
>   
>   total: 2 errors, 0 warnings, 396 lines checked
>   
>   /tmp/v4.patch has style problems, please review.
>   
>   If any of these errors are false positives, please report
>   them to the maintainer, see CHECKPATCH in MAINTAINERS.
> 
> Those false/positive are the only error checkptach reports on my side
> for the patch. This is the same if I copy/paste the content of the
> <pre></pre> with the patch in the following page:
> 
>  http://www.spinics.net/lists/arm-kernel/msg294759.html. 
> 
> I do not say you are wrong but I do not have a clue were the problem
> may come from.
> 
Oddly enough me not either. Let's assume the problem was on my side.
I sent you another round of comments a bit ago.

Thanks,
Guenter
--
To unsubscribe from this list: send the line "unsubscribe devicetree" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Mark Brown Dec. 16, 2013, 11:23 p.m. UTC | #6
On Mon, Dec 16, 2013 at 01:37:06PM -0800, Guenter Roeck wrote:

> Here is a snippet from the saved patch:

>  obj-$(CONFIG_RTC_DRV_IMXDI)    +=3D rtc-imxdi.o
>  obj-$(CONFIG_RTC_DRV_ISL1208)  +=3D rtc-isl1208.o
>  obj-$(CONFIG_RTC_DRV_ISL12022) +=3D rtc-isl12022.o
> +obj-$(CONFIG_RTC_DRV_ISL12057)  +=3D rtc-isl12057.o
>  obj-$(CONFIG_RTC_DRV_JZ4740)   +=3D rtc-jz4740.o
>  obj-$(CONFIG_RTC_DRV_LP8788)   +=3D rtc-lp8788.o
>  obj-$(CONFIG_RTC_DRV_LPC32XX)  +=3D rtc-lpc32xx.o

> Something is adding those '3D' after each '=' into the patch.

That's quoted printable MIME encoding of the =, presumably your MUA
doesn't do MIME (or the header went AWOL, though it's there in my copy).
diff mbox

Patch

diff --git a/Documentation/devicetree/bindings/i2c/trivial-devices.txt b/Documentation/devicetree/bindings/i2c/trivial-devices.txt
index b1cb341..cdf1430 100644
--- a/Documentation/devicetree/bindings/i2c/trivial-devices.txt
+++ b/Documentation/devicetree/bindings/i2c/trivial-devices.txt
@@ -39,6 +39,7 @@  fsl,sgtl5000		SGTL5000: Ultra Low-Power Audio Codec
 gmt,g751		G751: Digital Temperature Sensor and Thermal Watchdog with Two-Wire Interface
 infineon,slb9635tt	Infineon SLB9635 (Soft-) I2C TPM (old protocol, max 100khz)
 infineon,slb9645tt	Infineon SLB9645 I2C TPM (new protocol, max 400khz)
+isl,isl12057		Intersil ISL12057 I2C RTC Chip
 maxim,ds1050		5 Bit Programmable, Pulse-Width Modulator
 maxim,max1237		Low-Power, 4-/12-Channel, 2-Wire Serial, 12-Bit ADCs
 maxim,max6625		9-Bit/12-Bit Temperature Sensors with I²C-Compatible Serial Interface
diff --git a/Documentation/devicetree/bindings/vendor-prefixes.txt b/Documentation/devicetree/bindings/vendor-prefixes.txt
index edbb8d8..ed0f63f 100644
--- a/Documentation/devicetree/bindings/vendor-prefixes.txt
+++ b/Documentation/devicetree/bindings/vendor-prefixes.txt
@@ -39,6 +39,7 @@  ibm	International Business Machines (IBM)
 idt	Integrated Device Technologies, Inc.
 img	Imagination Technologies Ltd.
 intercontrol	Inter Control Group
+isl	Intersil
 lg	LG Corporation
 linux	Linux-specific binding
 lsi	LSI Corp. (LSI Logic)
diff --git a/drivers/rtc/Kconfig b/drivers/rtc/Kconfig
index 0077302..9608210 100644
--- a/drivers/rtc/Kconfig
+++ b/drivers/rtc/Kconfig
@@ -304,6 +304,17 @@  config RTC_DRV_ISL12022
 	  This driver can also be built as a module. If so, the module
 	  will be called rtc-isl12022.
 
+config RTC_DRV_ISL12057
+       depends on I2C
+       select REGMAP_I2C
+       tristate "Intersil ISL12057"
+       help
+	  If you say yes here you get support for the Intersil ISL12057
+	  I2C RTC chip.
+
+	  This driver can also be built as a module. If so, the module
+	  will be called rtc-isl12057.
+
 config RTC_DRV_X1205
 	tristate "Xicor/Intersil X1205"
 	help
diff --git a/drivers/rtc/Makefile b/drivers/rtc/Makefile
index 27b4bd8..6cd50e5 100644
--- a/drivers/rtc/Makefile
+++ b/drivers/rtc/Makefile
@@ -58,6 +58,7 @@  obj-$(CONFIG_RTC_DRV_HID_SENSOR_TIME) += rtc-hid-sensor-time.o
 obj-$(CONFIG_RTC_DRV_IMXDI)	+= rtc-imxdi.o
 obj-$(CONFIG_RTC_DRV_ISL1208)	+= rtc-isl1208.o
 obj-$(CONFIG_RTC_DRV_ISL12022)	+= rtc-isl12022.o
+obj-$(CONFIG_RTC_DRV_ISL12057)  += rtc-isl12057.o
 obj-$(CONFIG_RTC_DRV_JZ4740)	+= rtc-jz4740.o
 obj-$(CONFIG_RTC_DRV_LP8788)	+= rtc-lp8788.o
 obj-$(CONFIG_RTC_DRV_LPC32XX)	+= rtc-lpc32xx.o
diff --git a/drivers/rtc/rtc-isl12057.c b/drivers/rtc/rtc-isl12057.c
new file mode 100644
index 0000000..8a1851e
--- /dev/null
+++ b/drivers/rtc/rtc-isl12057.c
@@ -0,0 +1,358 @@ 
+/*
+ * rtc-isl12057 - Driver for Intersil ISL12057 I2C Real Time Clock
+ *
+ * Copyright (C) 2013, Arnaud EBALARD <arno@natisbad.org>
+ *
+ * This work is largely based on Intersil ISL1208 driver developed by
+ * Hebert Valerio Riedel <hvr@gnu.org>.
+ *
+ * Detailed datasheet on which this development is based is available here:
+ *
+ *  http://natisbad.org/NAS2/refs/ISL12057.pdf
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation.
+ */
+
+#include <linux/module.h>
+#include <linux/mutex.h>
+#include <linux/rtc.h>
+#include <linux/i2c.h>
+#include <linux/bcd.h>
+#include <linux/rtc.h>
+#include <linux/of.h>
+#include <linux/of_device.h>
+#include <linux/regmap.h>
+
+#define DRV_NAME "rtc-isl12057"
+
+/* RTC section */
+#define ISL12057_REG_RTC_SC     0x00 /* Seconds */
+#define ISL12057_REG_RTC_MN     0x01 /* Minutes */
+#define ISL12057_REG_RTC_HR     0x02 /* Hours */
+#define ISL12057_REG_RTC_HR_PM  BIT(5) /* AM/PM bit in 12h format */
+#define ISL12057_REG_RTC_HR_MIL BIT(6) /* 24h/12h format */
+#define ISL12057_REG_RTC_DW     0x03 /* Day of the Week */
+#define ISL12057_REG_RTC_DT     0x04 /* Date */
+#define ISL12057_REG_RTC_MO     0x05 /* Month */
+#define ISL12057_REG_RTC_YR     0x06 /* Year */
+#define ISL12057_RTC_SEC_LEN    7
+
+/* Alarm 1 section */
+#define ISL12057_REG_A1_SC      0x07 /* Alarm 1 Seconds */
+#define ISL12057_REG_A1_MN      0x08 /* Alarm 1 Minutes */
+#define ISL12057_REG_A1_HR      0x09 /* Alarm 1 Hours */
+#define ISL12057_REG_A1_HR_PM   BIT(5) /* AM/PM bit in 12h format */
+#define ISL12057_REG_A1_HR_MIL  BIT(6) /* 24h/12h format */
+#define ISL12057_REG_A1_DWDT    0x0A /* Alarm 1 Date / Day of the week */
+#define ISL12057_REG_A1_DWDT_B  BIT(6) /* DW / DT selection bit */
+#define ISL12057_A1_SEC_LEN     4
+
+/* Alarm 2 section */
+#define ISL12057_REG_A2_MN      0x0B /* Alarm 2 Minutes */
+#define ISL12057_REG_A2_HR      0x0C /* Alarm 2 Hours */
+#define ISL12057_REG_A2_DWDT    0x0D /* Alarm 2 Date / Day of the week */
+#define ISL12057_A2_SEC_LEN     3
+
+/* Control/Status registers */
+#define ISL12057_REG_INT        0x0E
+#define ISL12057_REG_INT_A1IE   BIT(0) /* Alarm 1 interrupt enable bit */
+#define ISL12057_REG_INT_A2IE   BIT(1) /* Alarm 2 interrupt enable bit */
+#define ISL12057_REG_INT_INTCN  BIT(2) /* Interrupt control enable bit */
+#define ISL12057_REG_INT_RS1    BIT(3) /* Freq out control bit 1 */
+#define ISL12057_REG_INT_RS2    BIT(4) /* Freq out control bit 2 */
+#define ISL12057_REG_INT_EOSC   BIT(7) /* Oscillator enable bit */
+
+#define ISL12057_REG_SR         0x0F
+#define ISL12057_REG_SR_A1F     BIT(0) /* Alarm 1 interrupt bit */
+#define ISL12057_REG_SR_A2F     BIT(1) /* Alarm 2 interrupt bit */
+#define ISL12057_REG_SR_OSF     BIT(7) /* Oscillator failure bit */
+
+/* Register memory map length */
+#define ISL12057_MEM_MAP_LEN    0x10
+
+static struct i2c_driver isl12057_driver;
+
+struct isl12057_rtc_data {
+	struct rtc_device *rtc;
+	struct regmap *regmap;
+	struct mutex lock;
+};
+
+static void isl12057_rtc_regs_to_tm(struct rtc_time *tm, u8 *regs)
+{
+	tm->tm_sec = bcd2bin(regs[ISL12057_REG_RTC_SC]);
+	tm->tm_min = bcd2bin(regs[ISL12057_REG_RTC_MN]);
+
+	if (regs[ISL12057_REG_RTC_HR] & ISL12057_REG_RTC_HR_MIL) { /* AM/PM */
+		tm->tm_hour = bcd2bin(regs[ISL12057_REG_RTC_HR] & 0x0f);
+		if (regs[ISL12057_REG_RTC_HR] & ISL12057_REG_RTC_HR_PM)
+			tm->tm_hour += 12;
+	} else {                                            /* 24 hour mode */
+		tm->tm_hour = bcd2bin(regs[ISL12057_REG_RTC_HR] & 0x3f);
+	}
+
+	tm->tm_mday = bcd2bin(regs[ISL12057_REG_RTC_DT]);
+	tm->tm_wday = bcd2bin(regs[ISL12057_REG_RTC_DW]) - 1; /* starts at 1 */
+	tm->tm_mon  = bcd2bin(regs[ISL12057_REG_RTC_MO]) - 1; /* starts at 1 */
+	tm->tm_year = bcd2bin(regs[ISL12057_REG_RTC_YR]) + 100;
+}
+
+static int isl12057_rtc_tm_to_regs(u8 *regs, struct rtc_time *tm)
+{
+	/*
+	 * The clock has an 8 bit wide bcd-coded register for the year.
+	 * tm_year is an offset from 1900 and we are interested in the
+	 * 2000-2099 range, so any value less than 100 is invalid.
+	 */
+	if (tm->tm_year < 100)
+		return -EINVAL;
+
+	regs[ISL12057_REG_RTC_SC] = bin2bcd(tm->tm_sec);
+	regs[ISL12057_REG_RTC_MN] = bin2bcd(tm->tm_min);
+	regs[ISL12057_REG_RTC_HR] = bin2bcd(tm->tm_hour); /* 24-hour format */
+	regs[ISL12057_REG_RTC_DT] = bin2bcd(tm->tm_mday);
+	regs[ISL12057_REG_RTC_MO] = bin2bcd(tm->tm_mon + 1);
+	regs[ISL12057_REG_RTC_YR] = bin2bcd(tm->tm_year - 100);
+	regs[ISL12057_REG_RTC_DW] = bin2bcd(tm->tm_wday + 1);
+
+	return 0;
+}
+
+/*
+ * Try and match register bits w/ fixed null values to see whether we
+ * are dealing with an ISL12057.
+ */
+static int isl12057_i2c_validate_chip(struct regmap *regmap)
+{
+	u8 regs[ISL12057_MEM_MAP_LEN];
+	u8 mask[ISL12057_MEM_MAP_LEN] = { 0x80, 0x80, 0x80, 0xf8,
+					  0xc0, 0x60, 0x00, 0x00,
+					  0x00, 0x00, 0x00, 0x00,
+					  0x00, 0x00, 0x60, 0x7c };
+	int ret, i;
+
+	ret = regmap_bulk_read(regmap, 0, regs, ISL12057_MEM_MAP_LEN);
+	if (ret)
+		return ret;
+
+	for (i = 0; i < ISL12057_MEM_MAP_LEN; ++i) {
+		if (regs[i] & mask[i])	/* check if bits are cleared */
+			return -ENODEV;
+	}
+
+	return 0;
+}
+
+static int isl12057_rtc_read_time(struct device *dev, struct rtc_time *tm)
+{
+	struct isl12057_rtc_data *data = dev_get_drvdata(dev);
+	u8 regs[ISL12057_RTC_SEC_LEN];
+	int ret;
+
+	mutex_lock(&data->lock);
+	ret = regmap_bulk_read(data->regmap, ISL12057_REG_RTC_SC, regs,
+			       ISL12057_RTC_SEC_LEN);
+	mutex_unlock(&data->lock);
+
+	if (ret) {
+		dev_err(dev, "%s: RTC read failed\n", __func__);
+		return ret;
+	}
+
+	isl12057_rtc_regs_to_tm(tm, regs);
+
+	return rtc_valid_tm(tm);
+}
+
+static int isl12057_rtc_set_time(struct device *dev, struct rtc_time *tm)
+{
+	struct isl12057_rtc_data *data = dev_get_drvdata(dev);
+	u8 regs[ISL12057_RTC_SEC_LEN];
+	int ret;
+
+	ret = isl12057_rtc_tm_to_regs(regs, tm);
+	if (ret)
+		return ret;
+
+	mutex_lock(&data->lock);
+	ret = regmap_bulk_write(data->regmap, ISL12057_REG_RTC_SC, regs,
+				ISL12057_RTC_SEC_LEN);
+	mutex_unlock(&data->lock);
+
+	if (ret)
+		dev_err(dev, "%s: RTC write failed\n", __func__);
+
+	return ret;
+}
+
+static int isl12057_rtc_proc(struct device *dev, struct seq_file *seq)
+{
+	struct isl12057_rtc_data *data = dev_get_drvdata(dev);
+	int reg, ret;
+
+	mutex_lock(&data->lock);
+
+	/* Status register */
+	ret = regmap_read(data->regmap, ISL12057_REG_SR, &reg);
+	if (ret) {
+		dev_err(dev, "%s: reading SR failed\n", __func__);
+		goto out;
+	}
+
+	seq_printf(seq, "status_reg\t:%s%s%s (0x%.2x)\n",
+		   (reg & ISL12057_REG_SR_OSF) ? " OSF" : "",
+		   (reg & ISL12057_REG_SR_A1F) ? " A1F" : "",
+		   (reg & ISL12057_REG_SR_A2F) ? " A2F" : "", reg);
+
+	/* Control register */
+	ret = regmap_read(data->regmap, ISL12057_REG_INT, &reg);
+	if (ret) {
+		dev_err(dev, "%s: reading INT failed\n", __func__);
+		goto out;
+	}
+
+	seq_printf(seq, "control_reg\t:%s%s%s%s%s%s (0x%.2x)\n",
+		   (reg & ISL12057_REG_INT_A1IE) ?  " A1IE"  : "",
+		   (reg & ISL12057_REG_INT_A2IE) ?  " A2IE"  : "",
+		   (reg & ISL12057_REG_INT_INTCN) ? " INTCN" : "",
+		   (reg & ISL12057_REG_INT_RS1) ?   " RS1"   : "",
+		   (reg & ISL12057_REG_INT_RS2) ?   " RS2"   : "",
+		   (reg & ISL12057_REG_INT_EOSC) ?  " EOSC"  : "", reg);
+
+ out:
+	mutex_unlock(&data->lock);
+
+	return ret;
+}
+
+/*
+ * Check current RTC status and enable/disable what needs to be. Return 0 if
+ * everything went ok and a negative value upon error. Note: this function
+ * is called early during init and hence does need mutex protection.
+ */
+static int isl12057_check_rtc_status(struct device *dev, struct regmap *regmap)
+{
+	int ret;
+
+	/* Enable oscillator if not already running */
+	ret = regmap_update_bits(regmap, ISL12057_REG_INT,
+				 ISL12057_REG_INT_EOSC, 0);
+	if (ret < 0) {
+		dev_err(dev, "Enable to enable oscillator\n");
+		return ret;
+	}
+
+	/* Clear oscillator failure bit if needed */
+	ret = regmap_update_bits(regmap, ISL12057_REG_SR,
+				 ISL12057_REG_SR_OSF, 0);
+	if (ret < 0) {
+		dev_err(dev, "Enable to clear oscillator failure bit\n");
+		return ret;
+	}
+
+	/* Clear alarm bit if needed */
+	ret = regmap_update_bits(regmap, ISL12057_REG_SR,
+				 ISL12057_REG_SR_A1F, 0);
+	if (ret < 0) {
+		dev_err(dev, "Enable to clear alarm bit\n");
+		return ret;
+	}
+
+	return 0;
+}
+
+static const struct rtc_class_ops rtc_ops = {
+	.read_time = isl12057_rtc_read_time,
+	.set_time = isl12057_rtc_set_time,
+	.proc = isl12057_rtc_proc,
+};
+
+static struct regmap_config isl12057_rtc_regmap_config = {
+	.reg_bits = 8,
+	.val_bits = 8,
+};
+
+static int isl12057_probe(struct i2c_client *client,
+			  const struct i2c_device_id *id)
+{
+	struct device *dev = &client->dev;
+	struct isl12057_rtc_data *data;
+	struct rtc_device *rtc;
+	struct regmap *regmap;
+	int ret;
+
+	if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C |
+				     I2C_FUNC_SMBUS_BYTE_DATA |
+				     I2C_FUNC_SMBUS_I2C_BLOCK))
+		return -ENODEV;
+
+	regmap = devm_regmap_init_i2c(client, &isl12057_rtc_regmap_config);
+	if (IS_ERR(regmap)) {
+		ret = PTR_ERR(regmap);
+		dev_err(dev, "regmap allocation failed: %d\n", ret);
+		return ret;
+	}
+
+	ret = isl12057_i2c_validate_chip(regmap);
+	if (ret)
+		return ret;
+
+	ret = isl12057_check_rtc_status(dev, regmap);
+	if (ret)
+		return ret;
+
+	data = devm_kzalloc(dev, sizeof(*data), GFP_KERNEL);
+	if (!data)
+		return -ENOMEM;
+
+	mutex_init(&data->lock);
+	data->regmap = regmap;
+	dev_set_drvdata(dev, data);
+
+	rtc = devm_rtc_device_register(dev, DRV_NAME, &rtc_ops, THIS_MODULE);
+	if (IS_ERR(rtc))
+		return PTR_ERR(rtc);
+	data->rtc = rtc;
+
+	return 0;
+}
+
+#ifdef CONFIG_OF
+static struct of_device_id isl12057_dt_match[] = {
+	{ .compatible = "isl,isl12057" },
+	{ },
+};
+#endif
+
+static const struct i2c_device_id isl12057_id[] = {
+	{ "isl12057", 0 },
+	{ }
+};
+MODULE_DEVICE_TABLE(i2c, isl12057_id);
+
+static struct i2c_driver isl12057_driver = {
+	.driver = {
+		.name = DRV_NAME,
+		.owner = THIS_MODULE,
+		.of_match_table = of_match_ptr(isl12057_dt_match),
+	},
+	.probe	  = isl12057_probe,
+	.id_table = isl12057_id,
+};
+module_i2c_driver(isl12057_driver);
+
+MODULE_AUTHOR("Arnaud EBALARD <arno@natisbad.org>");
+MODULE_DESCRIPTION("Intersil ISL12057 RTC driver");
+MODULE_LICENSE("GPL");