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- // 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 <[email protected]>
- */
- #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);
- /*
- * 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.
- */
- struct reg_sequence regs[] = {
- { NTXEC_REG_WRITE_SECOND, ntxec_reg8(0) },
- { NTXEC_REG_WRITE_YEAR, ntxec_reg8(tm->tm_year - 100) },
- { NTXEC_REG_WRITE_MONTH, ntxec_reg8(tm->tm_mon + 1) },
- { NTXEC_REG_WRITE_DAY, ntxec_reg8(tm->tm_mday) },
- { NTXEC_REG_WRITE_HOUR, ntxec_reg8(tm->tm_hour) },
- { NTXEC_REG_WRITE_MINUTE, ntxec_reg8(tm->tm_min) },
- { NTXEC_REG_WRITE_SECOND, ntxec_reg8(tm->tm_sec) },
- };
- return regmap_multi_reg_write(rtc->ec->regmap, regs, ARRAY_SIZE(regs));
- }
- 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;
- pdev->dev.of_node = pdev->dev.parent->of_node;
- 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 devm_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 <[email protected]>");
- MODULE_DESCRIPTION("RTC driver for Netronix EC");
- MODULE_LICENSE("GPL");
- MODULE_ALIAS("platform:ntxec-rtc");
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