On 23/01/2019 11:33:20-0700, Nick Crews wrote:
> From: Duncan Laurie <dlaurie@xxxxxxxxxx>
>
> 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.
>
> > 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>
> Acked-by: Enric Balletbo i Serra <enric.balletbo@xxxxxxxxxxxxx>
> Signed-off-by: Nick Crews <ncrews@xxxxxxxxxxxx>
Acked-by: Alexandre Belloni <alexandre.belloni@xxxxxxxxxxx>
> ---
>
> 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 | 14 ++
> drivers/rtc/Kconfig | 11 ++
> drivers/rtc/Makefile | 1 +
> drivers/rtc/rtc-wilco-ec.c | 177 ++++++++++++++++++++++++
> 4 files changed, 203 insertions(+)
> 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 e036d88b6dd8..7cfb047e2c89 100644
> --- a/drivers/platform/chrome/wilco_ec/core.c
> +++ b/drivers/platform/chrome/wilco_ec/core.c
> @@ -87,6 +87,20 @@ static int wilco_ec_probe(struct platform_device *pdev)
> goto destroy_mec;
> }
>
> + /*
> + * Register a RTC platform device that will get picked up by the RTC
> + * subsystem. This platform device will get freed when its parent device
> + * dev is unregistered.
> + */
> + child_pdev = platform_device_register_data(dev, "rtc-wilco-ec",
> + PLATFORM_DEVID_AUTO,
> + NULL, 0);
> + if (IS_ERR(child_pdev)) {
> + dev_err(dev, "Failed to create RTC platform device\n");
> + ret = PTR_ERR(child_pdev);
> + goto destroy_mec;
> + }
> +
> return 0;
>
> destroy_mec:
> 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 = ¶m,
> + .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");
> --
> 2.20.1.321.g9e740568ce-goog
>
--
Alexandre Belloni, Bootlin
Embedded Linux and Kernel engineering
https://bootlin.com
