Re: [PATCH v6 4/4] platform/chrome: rtc: Add RTC driver

From: Alexandre Belloni
Date: Fri Feb 08 2019 - 11:17:15 EST

On 08/02/2019 09:10:02-0700, Nick Crews wrote:
> Hi Enric and Alexandre,
>
> On Fri, Feb 8, 2019 at 5:18 AM Enric Balletbo i Serra
> <enric.balletbo@xxxxxxxxxxxxx> 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@xxxxxxxxxx>
> > > Signed-off-by: Nick Crews <ncrews@xxxxxxxxxxxx>
> >
> > I think that you missed :)
> >
> > Acked-by: Enric Balletbo i Serra <enric.balletbo@xxxxxxxxxxxxx>
> > Acked-by: Alexandre Belloni <alexandre.belloni@xxxxxxxxxxx>
> >
>
> 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?
>

I would think you could have kept mine.

> > > ---
> > >
> > > 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@xxxxxxxxxxxx>");
> > > +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