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435af89786
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@gmx.net> Acked-by: Alexandre Belloni <alexandre.belloni@bootlin.com> Signed-off-by: Lee Jones <lee.jones@linaro.org>
146 lines
3.9 KiB
C
146 lines
3.9 KiB
C
// SPDX-License-Identifier: GPL-2.0-or-later
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/*
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* The Netronix embedded controller is a microcontroller found in some
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* e-book readers designed by the original design manufacturer Netronix, Inc.
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* It contains RTC, battery monitoring, system power management, and PWM
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* functionality.
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*
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* This driver implements access to the RTC time and date.
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*
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* Copyright 2020 Jonathan Neuschäfer <j.neuschaefer@gmx.net>
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*/
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#include <linux/mfd/ntxec.h>
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#include <linux/module.h>
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#include <linux/platform_device.h>
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#include <linux/regmap.h>
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#include <linux/rtc.h>
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#include <linux/types.h>
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struct ntxec_rtc {
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struct device *dev;
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struct ntxec *ec;
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};
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#define NTXEC_REG_WRITE_YEAR 0x10
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#define NTXEC_REG_WRITE_MONTH 0x11
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#define NTXEC_REG_WRITE_DAY 0x12
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#define NTXEC_REG_WRITE_HOUR 0x13
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#define NTXEC_REG_WRITE_MINUTE 0x14
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#define NTXEC_REG_WRITE_SECOND 0x15
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#define NTXEC_REG_READ_YEAR_MONTH 0x20
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#define NTXEC_REG_READ_MDAY_HOUR 0x21
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#define NTXEC_REG_READ_MINUTE_SECOND 0x23
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static int ntxec_read_time(struct device *dev, struct rtc_time *tm)
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{
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struct ntxec_rtc *rtc = dev_get_drvdata(dev);
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unsigned int value;
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int res;
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retry:
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res = regmap_read(rtc->ec->regmap, NTXEC_REG_READ_MINUTE_SECOND, &value);
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if (res < 0)
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return res;
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tm->tm_min = value >> 8;
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tm->tm_sec = value & 0xff;
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res = regmap_read(rtc->ec->regmap, NTXEC_REG_READ_MDAY_HOUR, &value);
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if (res < 0)
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return res;
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tm->tm_mday = value >> 8;
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tm->tm_hour = value & 0xff;
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res = regmap_read(rtc->ec->regmap, NTXEC_REG_READ_YEAR_MONTH, &value);
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if (res < 0)
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return res;
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tm->tm_year = (value >> 8) + 100;
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tm->tm_mon = (value & 0xff) - 1;
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/*
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* Read the minutes/seconds field again. If it changed since the first
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* read, we can't assume that the values read so far are consistent,
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* and should start from the beginning.
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*/
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res = regmap_read(rtc->ec->regmap, NTXEC_REG_READ_MINUTE_SECOND, &value);
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if (res < 0)
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return res;
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if (tm->tm_min != value >> 8 || tm->tm_sec != (value & 0xff))
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goto retry;
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return 0;
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}
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static int ntxec_set_time(struct device *dev, struct rtc_time *tm)
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{
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struct ntxec_rtc *rtc = dev_get_drvdata(dev);
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/*
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* To avoid time overflows while we're writing the full date/time,
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* set the seconds field to zero before doing anything else. For the
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* next 59 seconds (plus however long it takes until the RTC's next
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* update of the second field), the seconds field will not overflow
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* into the other fields.
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*/
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struct reg_sequence regs[] = {
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{ NTXEC_REG_WRITE_SECOND, ntxec_reg8(0) },
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{ NTXEC_REG_WRITE_YEAR, ntxec_reg8(tm->tm_year - 100) },
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{ NTXEC_REG_WRITE_MONTH, ntxec_reg8(tm->tm_mon + 1) },
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{ NTXEC_REG_WRITE_DAY, ntxec_reg8(tm->tm_mday) },
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{ NTXEC_REG_WRITE_HOUR, ntxec_reg8(tm->tm_hour) },
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{ NTXEC_REG_WRITE_MINUTE, ntxec_reg8(tm->tm_min) },
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{ NTXEC_REG_WRITE_SECOND, ntxec_reg8(tm->tm_sec) },
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};
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return regmap_multi_reg_write(rtc->ec->regmap, regs, ARRAY_SIZE(regs));
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}
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static const struct rtc_class_ops ntxec_rtc_ops = {
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.read_time = ntxec_read_time,
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.set_time = ntxec_set_time,
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};
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static int ntxec_rtc_probe(struct platform_device *pdev)
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{
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struct rtc_device *dev;
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struct ntxec_rtc *rtc;
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pdev->dev.of_node = pdev->dev.parent->of_node;
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rtc = devm_kzalloc(&pdev->dev, sizeof(*rtc), GFP_KERNEL);
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if (!rtc)
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return -ENOMEM;
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rtc->dev = &pdev->dev;
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rtc->ec = dev_get_drvdata(pdev->dev.parent);
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platform_set_drvdata(pdev, rtc);
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dev = devm_rtc_allocate_device(&pdev->dev);
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if (IS_ERR(dev))
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return PTR_ERR(dev);
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dev->ops = &ntxec_rtc_ops;
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dev->range_min = RTC_TIMESTAMP_BEGIN_2000;
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dev->range_max = 9025257599LL; /* 2255-12-31 23:59:59 */
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return devm_rtc_register_device(dev);
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}
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static struct platform_driver ntxec_rtc_driver = {
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.driver = {
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.name = "ntxec-rtc",
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},
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.probe = ntxec_rtc_probe,
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};
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module_platform_driver(ntxec_rtc_driver);
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MODULE_AUTHOR("Jonathan Neuschäfer <j.neuschaefer@gmx.net>");
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MODULE_DESCRIPTION("RTC driver for Netronix EC");
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MODULE_LICENSE("GPL");
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MODULE_ALIAS("platform:ntxec-rtc");
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