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Date:   Fri, 8 Feb 2019 09:10:02 -0700
From:   Nick Crews <ncrews@...omium.org>
To:     Enric Balletbo i Serra <enric.balletbo@...labora.com>
Cc:     Alessandro Zummo <a.zummo@...ertech.it>,
        Benson Leung <bleung@...omium.org>,
        Duncan Laurie <dlaurie@...gle.com>,
        Alexandre Belloni <alexandre.belloni@...tlin.com>,
        dlaurie@...omium.org, dmitry.torokhov@...il.com,
        Enric Balletbo Serra <eballetbo@...il.com>,
        Guenter Roeck <groeck@...omium.org>,
        linux-kernel <linux-kernel@...r.kernel.org>,
        linux-rtc@...r.kernel.org, Simon Glass <sjg@...omium.org>
Subject: Re: [PATCH v6 4/4] platform/chrome: rtc: Add RTC driver

Hi Enric and Alexandre,

On Fri, Feb 8, 2019 at 5:18 AM Enric Balletbo i Serra
<enric.balletbo@...labora.com> wrote:
>
> Hi,
>
> On 8/2/19 2:23, Nick Crews wrote:
> > This Embedded Controller has an internal RTC that is exposed
> > as a standard RTC class driver with read/write functionality.
> >
> > The driver is added to the drivers/rtc/ so that the maintainer of that
> > directory will be able to comment on this change, as that maintainer is
> > the expert on this system. In addition, the driver code is called
> > indirectly after a corresponding device is registered from core.c,
> > as opposed to core.c registering the driver callbacks directly.
> >
> > To test:
> >> hwclock --show --rtc /dev/rtc1
> > 2007-12-31 16:01:20.460959-08:00
> >> hwclock --systohc --rtc /dev/rtc1
> >> hwclock --show --rtc /dev/rtc1
> > 2018-11-29 17:08:00.780793-08:00
> >
> >> hwclock --show --rtc /dev/rtc1
> > 2007-12-31 16:01:20.460959-08:00
> >> hwclock --systohc --rtc /dev/rtc1
> >> hwclock --show --rtc /dev/rtc1
> > 2018-11-29 17:08:00.780793-08:00
> >
> > Signed-off-by: Duncan Laurie <dlaurie@...gle.com>
> > Signed-off-by: Nick Crews <ncrews@...omium.org>
>
> I think that you missed :)
>
> Acked-by: Enric Balletbo i Serra <enric.balletbo@...labora.com>
> Acked-by: Alexandre Belloni <alexandre.belloni@...tlin.com>
>

Ah, I removed these because this version is a bit different from the
one that you Acked. Do you normally keep those sign-offs
even after making changes that you possibly might not like?

> > ---
> >
> > 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.
>
> Thanks,
>   Enric

Let me know if I can help with this. I based this off what I thought was the
most current master, SHA 74e96711e3379fc66630f2a1d184947f80cf2c48.
Was this not the correct commit to base these off of?

>
> [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;
> >  };
> >
> >  /**
> >

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