| 1 | |
| 2 | |
| 3 | * The Netronix embedded controller is a microcontroller found in some
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| 4 | * e-book readers designed by the original design manufacturer Netronix, Inc.
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| 5 | * It contains RTC, battery monitoring, system power management, and PWM
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| 6 | * functionality.
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| 7 | *
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| 8 | * This driver implements access to the RTC time and date.
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| 9 | *
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| 10 | * Copyright 2020 Jonathan Neuschäfer <[email protected]>
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| 11 |
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| 12 |
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| 13 | #include <linux/mfd/ntxec.h>
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| 14 | #include <linux/module.h>
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| 15 | #include <linux/platform_device.h>
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| 16 | #include <linux/regmap.h>
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| 17 | #include <linux/rtc.h>
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| 18 | #include <linux/types.h>
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| 19 |
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| 20 | struct ntxec_rtc {
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| 21 | struct device *dev;
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| 22 | struct ntxec *ec;
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| 23 | };
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| 24 |
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| 25 | #define NTXEC_REG_WRITE_YEAR 0x10
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| 26 | #define NTXEC_REG_WRITE_MONTH 0x11
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| 27 | #define NTXEC_REG_WRITE_DAY 0x12
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| 28 | #define NTXEC_REG_WRITE_HOUR 0x13
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| 29 | #define NTXEC_REG_WRITE_MINUTE 0x14
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| 30 | #define NTXEC_REG_WRITE_SECOND 0x15
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| 31 |
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| 32 | #define NTXEC_REG_READ_YEAR_MONTH 0x20
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| 33 | #define NTXEC_REG_READ_MDAY_HOUR 0x21
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| 34 | #define NTXEC_REG_READ_MINUTE_SECOND 0x23
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| 35 |
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| 36 | static int ntxec_read_time(struct device *dev, struct rtc_time *tm)
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| 37 | {
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| 38 | struct ntxec_rtc *rtc = dev_get_drvdata(dev);
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| 39 | unsigned int value;
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| 40 | int res;
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| 41 |
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| 42 | retry:
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| 43 | res = regmap_read(rtc->ec->regmap, NTXEC_REG_READ_MINUTE_SECOND, &value);
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| 44 | if (res < 0)
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| 45 | return res;
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| 46 |
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| 47 | tm->tm_min = value >> 8;
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| 48 | tm->tm_sec = value & 0xff;
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| 49 |
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| 50 | res = regmap_read(rtc->ec->regmap, NTXEC_REG_READ_MDAY_HOUR, &value);
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| 51 | if (res < 0)
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| 52 | return res;
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| 53 |
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| 54 | tm->tm_mday = value >> 8;
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| 55 | tm->tm_hour = value & 0xff;
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| 56 |
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| 57 | res = regmap_read(rtc->ec->regmap, NTXEC_REG_READ_YEAR_MONTH, &value);
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| 58 | if (res < 0)
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| 59 | return res;
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| 60 |
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| 61 | tm->tm_year = (value >> 8) + 100;
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| 62 | tm->tm_mon = (value & 0xff) - 1;
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| 63 |
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| 64 | |
| 65 | * Read the minutes/seconds field again. If it changed since the first
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| 66 | * read, we can't assume that the values read so far are consistent,
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| 67 | * and should start from the beginning.
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| 68 |
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| 69 | res = regmap_read(rtc->ec->regmap, NTXEC_REG_READ_MINUTE_SECOND, &value);
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| 70 | if (res < 0)
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| 71 | return res;
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| 72 |
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| 73 | if (tm->tm_min != value >> 8 || tm->tm_sec != (value & 0xff))
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| 74 | goto retry;
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| 75 |
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| 76 | return 0;
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| 77 | }
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| 78 |
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| 79 | static int ntxec_set_time(struct device *dev, struct rtc_time *tm)
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| 80 | {
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| 81 | struct ntxec_rtc *rtc = dev_get_drvdata(dev);
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| 82 |
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| 83 | |
| 84 | * To avoid time overflows while we're writing the full date/time,
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| 85 | * set the seconds field to zero before doing anything else. For the
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| 86 | * next 59 seconds (plus however long it takes until the RTC's next
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| 87 | * update of the second field), the seconds field will not overflow
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| 88 | * into the other fields.
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| 89 |
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| 90 | struct reg_sequence regs[] = {
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| 91 | { NTXEC_REG_WRITE_SECOND, ntxec_reg8(0) },
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| 92 | { NTXEC_REG_WRITE_YEAR, ntxec_reg8(tm->tm_year - 100) },
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| 93 | { NTXEC_REG_WRITE_MONTH, ntxec_reg8(tm->tm_mon + 1) },
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| 94 | { NTXEC_REG_WRITE_DAY, ntxec_reg8(tm->tm_mday) },
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| 95 | { NTXEC_REG_WRITE_HOUR, ntxec_reg8(tm->tm_hour) },
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| 96 | { NTXEC_REG_WRITE_MINUTE, ntxec_reg8(tm->tm_min) },
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| 97 | { NTXEC_REG_WRITE_SECOND, ntxec_reg8(tm->tm_sec) },
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| 98 | };
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| 99 |
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| 100 | return regmap_multi_reg_write(rtc->ec->regmap, regs, ARRAY_SIZE(regs));
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| 101 | }
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| 102 |
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| 103 | static const struct rtc_class_ops ntxec_rtc_ops = {
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| 104 | .read_time = ntxec_read_time,
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| 105 | .set_time = ntxec_set_time,
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| 106 | };
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| 107 |
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| 108 | static int ntxec_rtc_probe(struct platform_device *pdev)
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| 109 | {
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| 110 | struct rtc_device *dev;
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| 111 | struct ntxec_rtc *rtc;
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| 112 |
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| 113 | device_set_of_node_from_dev(&pdev->dev, pdev->dev.parent);
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| 114 |
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| 115 | rtc = devm_kzalloc(&pdev->dev, sizeof(*rtc), GFP_KERNEL);
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| 116 | if (!rtc)
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| 117 | return -ENOMEM;
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| 118 |
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| 119 | rtc->dev = &pdev->dev;
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| 120 | rtc->ec = dev_get_drvdata(pdev->dev.parent);
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| 121 | platform_set_drvdata(pdev, rtc);
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| 122 |
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| 123 | dev = devm_rtc_allocate_device(&pdev->dev);
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| 124 | if (IS_ERR(dev))
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| 125 | return PTR_ERR(dev);
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| 126 |
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| 127 | dev->ops = &ntxec_rtc_ops;
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| 128 | dev->range_min = RTC_TIMESTAMP_BEGIN_2000;
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| 129 | dev->range_max = 9025257599LL;
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| 130 |
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| 131 | return devm_rtc_register_device(dev);
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| 132 | }
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| 133 |
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| 134 | static struct platform_driver ntxec_rtc_driver = {
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| 135 | .driver = {
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| 136 | .name = "ntxec-rtc",
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| 137 | },
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| 138 | .probe = ntxec_rtc_probe,
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| 139 | };
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| 140 | module_platform_driver(ntxec_rtc_driver);
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| 141 |
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| 142 | MODULE_AUTHOR("Jonathan Neuschäfer <[email protected]>");
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| 143 | MODULE_DESCRIPTION("RTC driver for Netronix EC");
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| 144 | MODULE_LICENSE("GPL");
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| 145 | MODULE_ALIAS("platform:ntxec-rtc");
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