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@xxxxxxx> --- v4: - Remove "driver" from Kconfig entry for consistency with most other entries - Add missing MODULE_ALIAS line - Give NTXEC_REG_READ_ macros longer names - Solve the read tearing issue using Alexandre Belloni's algorithm - Solve the write tearing issue using Uwe Kleine-König's algorithm - Spell out ODM v3: - https://lore.kernel.org/lkml/20200924192455.2484005-6-j.neuschaefer@xxxxxxx/ - 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@xxxxxxx/ - 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 | 158 ++++++++++++++++++++++++++++++++++++++++ 3 files changed, 167 insertions(+) create mode 100644 drivers/rtc/rtc-ntxec.c diff --git a/drivers/rtc/Kconfig b/drivers/rtc/Kconfig index 65ad9d0b47ab1..fe009949728b3 100644 --- a/drivers/rtc/Kconfig +++ b/drivers/rtc/Kconfig @@ -1311,6 +1311,14 @@ 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" + 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 + original design manufacturer Netronix. + comment "on-CPU RTC drivers" config RTC_DRV_ASM9260 diff --git a/drivers/rtc/Makefile b/drivers/rtc/Makefile index bfb57464118d0..5f2a7582b2780 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..dad5aba2852f1 --- /dev/null +++ b/drivers/rtc/rtc-ntxec.c @@ -0,0 +1,158 @@ +// SPDX-License-Identifier: GPL-2.0-or-later +/* + * The Netronix embedded controller is a microcontroller found in some + * e-book readers designed by the original design manufacturer 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@xxxxxxx> + */ + +#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_YEAR_MONTH 0x20 +#define NTXEC_REG_READ_MDAY_HOUR 0x21 +#define NTXEC_REG_READ_MINUTE_SECOND 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; + +retry: + res = regmap_read(rtc->ec->regmap, NTXEC_REG_READ_MINUTE_SECOND, &value); + if (res < 0) + return res; + + tm->tm_min = value >> 8; + tm->tm_sec = value & 0xff; + + res = regmap_read(rtc->ec->regmap, NTXEC_REG_READ_MDAY_HOUR, &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_YEAR_MONTH, &value); + if (res < 0) + return res; + + tm->tm_year = (value >> 8) + 100; + tm->tm_mon = (value & 0xff) - 1; + + /* + * Read the minutes/seconds field again. If it changed since the first + * read, we can't assume that the values read so far are consistent, + * and should start from the beginning. + */ + res = regmap_read(rtc->ec->regmap, NTXEC_REG_READ_MINUTE_SECOND, &value); + if (res < 0) + return res; + + if (tm->tm_min != value >> 8 || tm->tm_sec != (value & 0xff)) + goto retry; + + 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; + + /* + * To avoid time overflows while we're writing the full date/time, + * set the seconds field to zero before doing anything else. For the + * next 59 seconds (plus however long it takes until the RTC's next + * update of the second field), the seconds field will not overflow + * into the other fields. + */ + res = regmap_write(rtc->ec->regmap, NTXEC_REG_WRITE_SECOND, ntxec_reg8(0)); + if (res) + return res; + + 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); + +MODULE_AUTHOR("Jonathan Neuschäfer <j.neuschaefer@xxxxxxx>"); +MODULE_DESCRIPTION("RTC driver for Netronix EC"); +MODULE_LICENSE("GPL"); +MODULE_ALIAS("platform:ntxec-rtc"); -- 2.29.2
