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Date:   Fri, 8 Feb 2019 17:16:05 +0100
From:   Alexandre Belloni <alexandre.belloni@...tlin.com>
To:     Enric Balletbo i Serra <enric.balletbo@...labora.com>
Cc:     Nick Crews <ncrews@...omium.org>, linux-kernel@...r.kernel.org,
        eballetbo@...il.com, sjg@...omium.org, dmitry.torokhov@...il.com,
        groeck@...omium.org, dlaurie@...omium.org,
        Duncan Laurie <dlaurie@...gle.com>, linux-rtc@...r.kernel.org,
        Alessandro Zummo <a.zummo@...ertech.it>,
        Benson Leung <bleung@...omium.org>
Subject: Re: [PATCH v6 4/4] platform/chrome: rtc: Add RTC driver

On 08/02/2019 13:18:38+0100, Enric Balletbo i Serra wrote:
> > Changes in v6:
> > - In the core, actually unregister the RTC child platform_device.
> > 
> > Changes in v5: None
> > Changes in v4:
> > - Change me email to @chromium.org from @google.com
> > - Move "Add RTC driver" before "Add sysfs attributes" so that
> >   it could get accepted earlier, since it is less contentious
> > 
> > Changes in v3:
> > - rm #define for driver name
> > - Don't compute weekday when reading from RTC.
> >   Still set weekday when writing, as RTC needs this
> >   to control advanced power scheduling
> > - rm check for invalid month data
> > - Set range_min and range_max on rtc_device
> > 
> > Changes in v2:
> > - rm license boiler plate
> > - rm "wilco_ec_rtc -" prefix in docstring
> > - Make rtc driver its own module within the drivers/rtc/ directory
> > - Register a rtc device from core.c that is picked up by this driver
> > 
> >  drivers/platform/chrome/wilco_ec/core.c |  22 ++-
> 
> Alexandre, this specific patch depends on the patches of the series to apply,
> and the first patches of the series also conflicts/depends on some patches
> queued in chrome-platform-5.1 branch [1]. Is it fine with you if I create an
> immutable branch and all go via your tree? Or what do you think? I am new here
> and I am not sure how to manage that.
> 

The series should probably go through the chrome tree. The only possible
conflict would be in drivers/rtc/Makefile and it should be easy enough
for Linus to solve.

> Thanks,
>   Enric
> 
> [1]
> https://git.kernel.org/pub/scm/linux/kernel/git/chrome-platform/linux.git/log/?h=chrome-platform-5.1
> 
> >  drivers/rtc/Kconfig                     |  11 ++
> >  drivers/rtc/Makefile                    |   1 +
> >  drivers/rtc/rtc-wilco-ec.c              | 177 ++++++++++++++++++++++++
> >  include/linux/platform_data/wilco-ec.h  |   2 +
> >  5 files changed, 211 insertions(+), 2 deletions(-)
> >  create mode 100644 drivers/rtc/rtc-wilco-ec.c
> > 
> > diff --git a/drivers/platform/chrome/wilco_ec/core.c b/drivers/platform/chrome/wilco_ec/core.c
> > index ae86cae216fd..e67385ec5103 100644
> > --- a/drivers/platform/chrome/wilco_ec/core.c
> > +++ b/drivers/platform/chrome/wilco_ec/core.c
> > @@ -42,6 +42,7 @@ static int wilco_ec_probe(struct platform_device *pdev)
> >  {
> >  	struct device *dev = &pdev->dev;
> >  	struct wilco_ec_device *ec;
> > +	int ret;
> >  
> >  	ec = devm_kzalloc(dev, sizeof(*ec), GFP_KERNEL);
> >  	if (!ec)
> > @@ -70,21 +71,38 @@ static int wilco_ec_probe(struct platform_device *pdev)
> >  			     ec->io_packet->start + EC_MAILBOX_DATA_SIZE);
> >  
> >  	/*
> > -	 * Register a debugfs platform device that will get picked up by the
> > -	 * debugfs driver. Ignore failure.
> > +	 * Register a child device that will be found by the RTC driver.
> > +	 * Ignore failure.
> >  	 */
> >  	ec->debugfs_pdev = platform_device_register_data(dev,
> >  							 "wilco-ec-debugfs",
> >  							 PLATFORM_DEVID_AUTO,
> >  							 NULL, 0);
> >  
> > +	/* Register a child device that will be found by the RTC driver. */
> > +	ec->rtc_pdev = platform_device_register_data(dev, "rtc-wilco-ec",
> > +						     PLATFORM_DEVID_AUTO,
> > +						     NULL, 0);
> > +	if (IS_ERR(ec->rtc_pdev)) {
> > +		dev_err(dev, "Failed to create RTC platform device\n");
> > +		ret = PTR_ERR(ec->rtc_pdev);
> > +		goto unregister_debugfs;
> > +	}
> > +
> >  	return 0;
> > +
> > +unregister_debugfs:
> > +	if (ec->debugfs_pdev)
> > +		platform_device_unregister(ec->debugfs_pdev);
> > +	cros_ec_lpc_mec_destroy();
> > +	return ret;
> >  }
> >  
> >  static int wilco_ec_remove(struct platform_device *pdev)
> >  {
> >  	struct wilco_ec_device *ec = platform_get_drvdata(pdev);
> >  
> > +	platform_device_unregister(ec->rtc_pdev);
> >  	if (ec->debugfs_pdev)
> >  		platform_device_unregister(ec->debugfs_pdev);
> >  
> > diff --git a/drivers/rtc/Kconfig b/drivers/rtc/Kconfig
> > index 225b0b8516f3..d5063c791515 100644
> > --- a/drivers/rtc/Kconfig
> > +++ b/drivers/rtc/Kconfig
> > @@ -1814,4 +1814,15 @@ config RTC_DRV_GOLDFISH
> >  	  Goldfish is a code name for the virtual platform developed by Google
> >  	  for Android emulation.
> >  
> > +config RTC_DRV_WILCO_EC
> > +	tristate "Wilco EC RTC"
> > +	depends on WILCO_EC
> > +	default m
> > +	help
> > +	  If you say yes here, you get read/write support for the Real Time
> > +	  Clock on the Wilco Embedded Controller (Wilco is a kind of Chromebook)
> > +
> > +	  This can also be built as a module. If so, the module will
> > +	  be named "rtc_wilco_ec".
> > +
> >  endif # RTC_CLASS
> > diff --git a/drivers/rtc/Makefile b/drivers/rtc/Makefile
> > index df022d820bee..6255ea78da25 100644
> > --- a/drivers/rtc/Makefile
> > +++ b/drivers/rtc/Makefile
> > @@ -172,6 +172,7 @@ obj-$(CONFIG_RTC_DRV_V3020)	+= rtc-v3020.o
> >  obj-$(CONFIG_RTC_DRV_VR41XX)	+= rtc-vr41xx.o
> >  obj-$(CONFIG_RTC_DRV_VRTC)	+= rtc-mrst.o
> >  obj-$(CONFIG_RTC_DRV_VT8500)	+= rtc-vt8500.o
> > +obj-$(CONFIG_RTC_DRV_WILCO_EC)	+= rtc-wilco-ec.o
> >  obj-$(CONFIG_RTC_DRV_WM831X)	+= rtc-wm831x.o
> >  obj-$(CONFIG_RTC_DRV_WM8350)	+= rtc-wm8350.o
> >  obj-$(CONFIG_RTC_DRV_X1205)	+= rtc-x1205.o
> > diff --git a/drivers/rtc/rtc-wilco-ec.c b/drivers/rtc/rtc-wilco-ec.c
> > new file mode 100644
> > index 000000000000..35cc56114c1c
> > --- /dev/null
> > +++ b/drivers/rtc/rtc-wilco-ec.c
> > @@ -0,0 +1,177 @@
> > +// SPDX-License-Identifier: GPL-2.0
> > +/*
> > + * RTC interface for Wilco Embedded Controller with R/W abilities
> > + *
> > + * Copyright 2018 Google LLC
> > + *
> > + * The corresponding platform device is typically registered in
> > + * drivers/platform/chrome/wilco_ec/core.c
> > + */
> > +
> > +#include <linux/bcd.h>
> > +#include <linux/err.h>
> > +#include <linux/kernel.h>
> > +#include <linux/module.h>
> > +#include <linux/platform_device.h>
> > +#include <linux/platform_data/wilco-ec.h>
> > +#include <linux/rtc.h>
> > +#include <linux/timekeeping.h>
> > +
> > +#define EC_COMMAND_CMOS			0x7c
> > +#define EC_CMOS_TOD_WRITE		0x02
> > +#define EC_CMOS_TOD_READ		0x08
> > +
> > +/**
> > + * struct ec_rtc_read - Format of RTC returned by EC.
> > + * @second: Second value (0..59)
> > + * @minute: Minute value (0..59)
> > + * @hour: Hour value (0..23)
> > + * @day: Day value (1..31)
> > + * @month: Month value (1..12)
> > + * @year: Year value (full year % 100)
> > + * @century: Century value (full year / 100)
> > + *
> > + * All values are presented in binary (not BCD).
> > + */
> > +struct ec_rtc_read {
> > +	u8 second;
> > +	u8 minute;
> > +	u8 hour;
> > +	u8 day;
> > +	u8 month;
> > +	u8 year;
> > +	u8 century;
> > +} __packed;
> > +
> > +/**
> > + * struct ec_rtc_write - Format of RTC sent to the EC.
> > + * @param: EC_CMOS_TOD_WRITE
> > + * @century: Century value (full year / 100)
> > + * @year: Year value (full year % 100)
> > + * @month: Month value (1..12)
> > + * @day: Day value (1..31)
> > + * @hour: Hour value (0..23)
> > + * @minute: Minute value (0..59)
> > + * @second: Second value (0..59)
> > + * @weekday: Day of the week (0=Saturday)
> > + *
> > + * All values are presented in BCD.
> > + */
> > +struct ec_rtc_write {
> > +	u8 param;
> > +	u8 century;
> > +	u8 year;
> > +	u8 month;
> > +	u8 day;
> > +	u8 hour;
> > +	u8 minute;
> > +	u8 second;
> > +	u8 weekday;
> > +} __packed;
> > +
> > +int wilco_ec_rtc_read(struct device *dev, struct rtc_time *tm)
> > +{
> > +	struct wilco_ec_device *ec = dev_get_drvdata(dev->parent);
> > +	u8 param = EC_CMOS_TOD_READ;
> > +	struct ec_rtc_read rtc;
> > +	struct wilco_ec_message msg = {
> > +		.type = WILCO_EC_MSG_LEGACY,
> > +		.flags = WILCO_EC_FLAG_RAW_RESPONSE,
> > +		.command = EC_COMMAND_CMOS,
> > +		.request_data = &param,
> > +		.request_size = sizeof(param),
> > +		.response_data = &rtc,
> > +		.response_size = sizeof(rtc),
> > +	};
> > +	int ret;
> > +
> > +	ret = wilco_ec_mailbox(ec, &msg);
> > +	if (ret < 0)
> > +		return ret;
> > +
> > +	tm->tm_sec	= rtc.second;
> > +	tm->tm_min	= rtc.minute;
> > +	tm->tm_hour	= rtc.hour;
> > +	tm->tm_mday	= rtc.day;
> > +	tm->tm_mon	= rtc.month - 1;
> > +	tm->tm_year	= rtc.year + (rtc.century * 100) - 1900;
> > +	tm->tm_yday	= rtc_year_days(tm->tm_mday, tm->tm_mon, tm->tm_year);
> > +
> > +	/* Don't compute day of week, we don't need it. */
> > +	tm->tm_wday = -1;
> > +
> > +	return 0;
> > +}
> > +
> > +int wilco_ec_rtc_write(struct device *dev, struct rtc_time *tm)
> > +{
> > +	struct wilco_ec_device *ec = dev_get_drvdata(dev->parent);
> > +	struct ec_rtc_write rtc;
> > +	struct wilco_ec_message msg = {
> > +		.type = WILCO_EC_MSG_LEGACY,
> > +		.flags = WILCO_EC_FLAG_RAW_RESPONSE,
> > +		.command = EC_COMMAND_CMOS,
> > +		.request_data = &rtc,
> > +		.request_size = sizeof(rtc),
> > +	};
> > +	int year = tm->tm_year + 1900;
> > +	/*
> > +	 * Convert from 0=Sunday to 0=Saturday for the EC
> > +	 * We DO need to set weekday because the EC controls battery charging
> > +	 * schedules that depend on the day of the week.
> > +	 */
> > +	int wday = tm->tm_wday == 6 ? 0 : tm->tm_wday + 1;
> > +	int ret;
> > +
> > +	rtc.param	= EC_CMOS_TOD_WRITE;
> > +	rtc.century	= bin2bcd(year / 100);
> > +	rtc.year	= bin2bcd(year % 100);
> > +	rtc.month	= bin2bcd(tm->tm_mon + 1);
> > +	rtc.day		= bin2bcd(tm->tm_mday);
> > +	rtc.hour	= bin2bcd(tm->tm_hour);
> > +	rtc.minute	= bin2bcd(tm->tm_min);
> > +	rtc.second	= bin2bcd(tm->tm_sec);
> > +	rtc.weekday	= bin2bcd(wday);
> > +
> > +	ret = wilco_ec_mailbox(ec, &msg);
> > +	if (ret < 0)
> > +		return ret;
> > +
> > +	return 0;
> > +}
> > +
> > +static const struct rtc_class_ops wilco_ec_rtc_ops = {
> > +	.read_time = wilco_ec_rtc_read,
> > +	.set_time = wilco_ec_rtc_write,
> > +};
> > +
> > +static int wilco_ec_rtc_probe(struct platform_device *pdev)
> > +{
> > +	struct rtc_device *rtc;
> > +
> > +	rtc = devm_rtc_allocate_device(&pdev->dev);
> > +	if (IS_ERR(rtc))
> > +		return PTR_ERR(rtc);
> > +
> > +	rtc->ops = &wilco_ec_rtc_ops;
> > +	/* EC only supports this century */
> > +	rtc->range_min = RTC_TIMESTAMP_BEGIN_2000;
> > +	rtc->range_max = RTC_TIMESTAMP_END_2099;
> > +	rtc->owner = THIS_MODULE;
> > +
> > +	return rtc_register_device(rtc);
> > +}
> > +
> > +static struct platform_driver wilco_ec_rtc_driver = {
> > +	.driver = {
> > +		.name = "rtc-wilco-ec",
> > +	},
> > +	.probe = wilco_ec_rtc_probe,
> > +};
> > +
> > +module_platform_driver(wilco_ec_rtc_driver);
> > +
> > +MODULE_ALIAS("platform:rtc-wilco-ec");
> > +MODULE_AUTHOR("Nick Crews <ncrews@...omium.org>");
> > +MODULE_LICENSE("GPL v2");
> > +MODULE_DESCRIPTION("Wilco EC RTC driver");
> > diff --git a/include/linux/platform_data/wilco-ec.h b/include/linux/platform_data/wilco-ec.h
> > index 5344975afa1a..446473a46b88 100644
> > --- a/include/linux/platform_data/wilco-ec.h
> > +++ b/include/linux/platform_data/wilco-ec.h
> > @@ -35,6 +35,7 @@
> >   *               is used to hold the request and the response.
> >   * @data_size: Size of the data buffer used for EC communication.
> >   * @debugfs_pdev: The child platform_device used by the debugfs sub-driver.
> > + * @rtc_pdev: The child platform_device used by the RTC sub-driver.
> >   */
> >  struct wilco_ec_device {
> >  	struct device *dev;
> > @@ -45,6 +46,7 @@ struct wilco_ec_device {
> >  	void *data_buffer;
> >  	size_t data_size;
> >  	struct platform_device *debugfs_pdev;
> > +	struct platform_device *rtc_pdev;
> >  };
> >  
> >  /**
> > 

-- 
Alexandre Belloni, Bootlin
Embedded Linux and Kernel engineering
https://bootlin.com

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