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145 lines
3.9 KiB
145 lines
3.9 KiB
// 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 <[email protected]> |
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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 <[email protected]>"); |
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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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