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

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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@xxxxxxxxxxxx>

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@xxxxxxxxxxxx>
> + *
> + * This work is largely based on Intersil ISL1208 driver developed by
> + * Hebert Valerio Riedel <hvr@xxxxxxx>.
> + *
> + * 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@xxxxxxxxxxxx>");
> +MODULE_DESCRIPTION("Intersil ISL12057 RTC driver");
> +MODULE_LICENSE("GPL");
> -- 
> 1.8.4.4
> 
> 
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