[PATCH v3 5/7] rtc: New driver for RTC in Netronix embedded controller

[Andreas Kemnade]

On Thu, 24 Sep 2020 21:24:53 +0200
Jonathan Neuschäfer <j.neuschaefer at gmx.net> wrote:

> With this driver, mainline Linux can keep its time and date in sync with
> the vendor kernel.
> 
> Advanced functionality like alarm and automatic power-on is not yet
> supported.
> 
> Signed-off-by: Jonathan Neuschäfer <j.neuschaefer at gmx.net>
> ---
> 
> v3:
> - Add email address to copyright line
> - Remove OF compatible string and don't include linux/of_device.h
> - Don't use a comma after sentinels
> - Avoid ret |= ... pattern
> - Move 8-bit register conversion to ntxec.h
> - Relicense as GPLv2 or later
> 
> v2:
> - https://lore.kernel.org/lkml/20200905133230.1014581-7-j.neuschaefer@gmx.net/
> - Rework top-of-file comment [Lee Jones]
> - Sort the #include lines [Alexandre Belloni]
> - don't align = signs in struct initializers [Uwe Kleine-König]
> - Switch to regmap
> - Fix register number used to read minutes and seconds
> - Prefix registers with NTXEC_REG_
> - Add help text to the Kconfig option
> - Use devm_rtc_allocate_device and rtc_register_device, set ->range_min and ->range_max
> ---
>  drivers/rtc/Kconfig     |   8 +++
>  drivers/rtc/Makefile    |   1 +
>  drivers/rtc/rtc-ntxec.c | 132 ++++++++++++++++++++++++++++++++++++++++
>  3 files changed, 141 insertions(+)
>  create mode 100644 drivers/rtc/rtc-ntxec.c
> 
> diff --git a/drivers/rtc/Kconfig b/drivers/rtc/Kconfig
> index 48c536acd777f..ae8f3dc36c9a3 100644
> --- a/drivers/rtc/Kconfig
> +++ b/drivers/rtc/Kconfig
> @@ -1301,6 +1301,14 @@ config RTC_DRV_CROS_EC
>  	  This driver can also be built as a module. If so, the module
>  	  will be called rtc-cros-ec.
> 
> +config RTC_DRV_NTXEC
> +	tristate "Netronix embedded controller RTC driver"
> +	depends on MFD_NTXEC
> +	help
> +	  Say yes here if you want to support the RTC functionality of the
> +	  embedded controller found in certain e-book readers designed by the
> +	  ODM Netronix.
> +
>  comment "on-CPU RTC drivers"
> 
>  config RTC_DRV_ASM9260
> diff --git a/drivers/rtc/Makefile b/drivers/rtc/Makefile
> index 880e08a409c3d..733479db18896 100644
> --- a/drivers/rtc/Makefile
> +++ b/drivers/rtc/Makefile
> @@ -111,6 +111,7 @@ obj-$(CONFIG_RTC_DRV_MT7622)	+= rtc-mt7622.o
>  obj-$(CONFIG_RTC_DRV_MV)	+= rtc-mv.o
>  obj-$(CONFIG_RTC_DRV_MXC)	+= rtc-mxc.o
>  obj-$(CONFIG_RTC_DRV_MXC_V2)	+= rtc-mxc_v2.o
> +obj-$(CONFIG_RTC_DRV_NTXEC)	+= rtc-ntxec.o
>  obj-$(CONFIG_RTC_DRV_OMAP)	+= rtc-omap.o
>  obj-$(CONFIG_RTC_DRV_OPAL)	+= rtc-opal.o
>  obj-$(CONFIG_RTC_DRV_PALMAS)	+= rtc-palmas.o
> diff --git a/drivers/rtc/rtc-ntxec.c b/drivers/rtc/rtc-ntxec.c
> new file mode 100644
> index 0000000000000..af23c7cc76544
> --- /dev/null
> +++ b/drivers/rtc/rtc-ntxec.c
> @@ -0,0 +1,132 @@
> +// SPDX-License-Identifier: GPL-2.0-or-later
> +/*
> + * The Netronix embedded controller is a microcontroller found in some
> + * e-book readers designed by the ODM Netronix, Inc. It contains RTC,
> + * battery monitoring, system power management, and PWM functionality.
> + *
> + * This driver implements access to the RTC time and date.
> + *
> + * Copyright 2020 Jonathan Neuschäfer <j.neuschaefer at gmx.net>
> + */
> +
> +#include <linux/mfd/ntxec.h>
> +#include <linux/module.h>
> +#include <linux/platform_device.h>
> +#include <linux/regmap.h>
> +#include <linux/rtc.h>
> +#include <linux/types.h>
> +
> +struct ntxec_rtc {
> +	struct device *dev;
> +	struct ntxec *ec;
> +};
> +
> +#define NTXEC_REG_WRITE_YEAR	0x10
> +#define NTXEC_REG_WRITE_MONTH	0x11
> +#define NTXEC_REG_WRITE_DAY	0x12
> +#define NTXEC_REG_WRITE_HOUR	0x13
> +#define NTXEC_REG_WRITE_MINUTE	0x14
> +#define NTXEC_REG_WRITE_SECOND	0x15
> +
> +#define NTXEC_REG_READ_YM	0x20
> +#define NTXEC_REG_READ_DH	0x21
> +#define NTXEC_REG_READ_MS	0x23
> +
> +static int ntxec_read_time(struct device *dev, struct rtc_time *tm)
> +{
> +	struct ntxec_rtc *rtc = dev_get_drvdata(dev);
> +	unsigned int value;
> +	int res;
> +
> +	res = regmap_read(rtc->ec->regmap, NTXEC_REG_READ_YM, &value);
> +	if (res < 0)
> +		return res;
> +
> +	tm->tm_year = (value >> 8) + 100;
> +	tm->tm_mon = (value & 0xff) - 1;
> +
> +	res = regmap_read(rtc->ec->regmap, NTXEC_REG_READ_DH, &value);
> +	if (res < 0)
> +		return res;
> +
> +	tm->tm_mday = value >> 8;
> +	tm->tm_hour = value & 0xff;
> +
> +	res = regmap_read(rtc->ec->regmap, NTXEC_REG_READ_MS, &value);
> +	if (res < 0)
> +		return res;
> +
> +	tm->tm_min = value >> 8;
> +	tm->tm_sec = value & 0xff;
> +
> +	return 0;
> +}
> +
> +static int ntxec_set_time(struct device *dev, struct rtc_time *tm)
> +{
> +	struct ntxec_rtc *rtc = dev_get_drvdata(dev);
> +	int res = 0;
> +
> +	res = regmap_write(rtc->ec->regmap, NTXEC_REG_WRITE_YEAR, ntxec_reg8(tm->tm_year - 100));
> +	if (res)
> +		return res;
> +
> +	res = regmap_write(rtc->ec->regmap, NTXEC_REG_WRITE_MONTH, ntxec_reg8(tm->tm_mon + 1));
> +	if (res)
> +		return res;
> +
> +	res = regmap_write(rtc->ec->regmap, NTXEC_REG_WRITE_DAY, ntxec_reg8(tm->tm_mday));
> +	if (res)
> +		return res;
> +
> +	res = regmap_write(rtc->ec->regmap, NTXEC_REG_WRITE_HOUR, ntxec_reg8(tm->tm_hour));
> +	if (res)
> +		return res;
> +
> +	res = regmap_write(rtc->ec->regmap, NTXEC_REG_WRITE_MINUTE, ntxec_reg8(tm->tm_min));
> +	if (res)
> +		return res;
> +
> +	return regmap_write(rtc->ec->regmap, NTXEC_REG_WRITE_SECOND, ntxec_reg8(tm->tm_sec));
> +}
> +
> +static const struct rtc_class_ops ntxec_rtc_ops = {
> +	.read_time = ntxec_read_time,
> +	.set_time = ntxec_set_time,
> +};
> +
> +static int ntxec_rtc_probe(struct platform_device *pdev)
> +{
> +	struct rtc_device *dev;
> +	struct ntxec_rtc *rtc;
> +
> +	rtc = devm_kzalloc(&pdev->dev, sizeof(*rtc), GFP_KERNEL);
> +	if (!rtc)
> +		return -ENOMEM;
> +
> +	rtc->dev = &pdev->dev;
> +	rtc->ec = dev_get_drvdata(pdev->dev.parent);
> +	platform_set_drvdata(pdev, rtc);
> +
> +	dev = devm_rtc_allocate_device(&pdev->dev);
> +	if (IS_ERR(dev))
> +		return PTR_ERR(dev);
> +
> +	dev->ops = &ntxec_rtc_ops;
> +	dev->range_min = RTC_TIMESTAMP_BEGIN_2000;
> +	dev->range_max = 9025257599LL; /* 2255-12-31 23:59:59 */
> +
> +	return rtc_register_device(dev);
> +}
> +
> +static struct platform_driver ntxec_rtc_driver = {
> +	.driver = {
> +		.name = "ntxec-rtc",
> +	},
> +	.probe = ntxec_rtc_probe,
> +};
> +module_platform_driver(ntxec_rtc_driver);
> +
I think module autoloading will not work without

MODULE_ALIAS("platform:ntxec-rtc");

Same for the pwm device.
> +MODULE_AUTHOR("Jonathan Neuschäfer <j.neuschaefer at gmx.net>");
> +MODULE_DESCRIPTION("RTC driver for Netronix EC");
> +MODULE_LICENSE("GPL");
> --
> 2.28.0
> 
> 

Regards,
Andreas