1 | // SPDX-License-Identifier: GPL-2.0-or-later |
2 | /* |
3 | * The Netronix embedded controller is a microcontroller found in some |
4 | * e-book readers designed by the original design manufacturer Netronix, Inc. |
5 | * It contains RTC, battery monitoring, system power management, and PWM |
6 | * functionality. |
7 | * |
8 | * This driver implements access to the RTC time and date. |
9 | * |
10 | * Copyright 2020 Jonathan Neuschäfer <j.neuschaefer@gmx.net> |
11 | */ |
12 | |
13 | #include <linux/mfd/ntxec.h> |
14 | #include <linux/module.h> |
15 | #include <linux/platform_device.h> |
16 | #include <linux/regmap.h> |
17 | #include <linux/rtc.h> |
18 | #include <linux/types.h> |
19 | |
20 | struct ntxec_rtc { |
21 | struct device *dev; |
22 | struct ntxec *ec; |
23 | }; |
24 | |
25 | #define NTXEC_REG_WRITE_YEAR 0x10 |
26 | #define NTXEC_REG_WRITE_MONTH 0x11 |
27 | #define NTXEC_REG_WRITE_DAY 0x12 |
28 | #define NTXEC_REG_WRITE_HOUR 0x13 |
29 | #define NTXEC_REG_WRITE_MINUTE 0x14 |
30 | #define NTXEC_REG_WRITE_SECOND 0x15 |
31 | |
32 | #define NTXEC_REG_READ_YEAR_MONTH 0x20 |
33 | #define NTXEC_REG_READ_MDAY_HOUR 0x21 |
34 | #define NTXEC_REG_READ_MINUTE_SECOND 0x23 |
35 | |
36 | static int ntxec_read_time(struct device *dev, struct rtc_time *tm) |
37 | { |
38 | struct ntxec_rtc *rtc = dev_get_drvdata(dev); |
39 | unsigned int value; |
40 | int res; |
41 | |
42 | retry: |
43 | res = regmap_read(map: rtc->ec->regmap, NTXEC_REG_READ_MINUTE_SECOND, val: &value); |
44 | if (res < 0) |
45 | return res; |
46 | |
47 | tm->tm_min = value >> 8; |
48 | tm->tm_sec = value & 0xff; |
49 | |
50 | res = regmap_read(map: rtc->ec->regmap, NTXEC_REG_READ_MDAY_HOUR, val: &value); |
51 | if (res < 0) |
52 | return res; |
53 | |
54 | tm->tm_mday = value >> 8; |
55 | tm->tm_hour = value & 0xff; |
56 | |
57 | res = regmap_read(map: rtc->ec->regmap, NTXEC_REG_READ_YEAR_MONTH, val: &value); |
58 | if (res < 0) |
59 | return res; |
60 | |
61 | tm->tm_year = (value >> 8) + 100; |
62 | tm->tm_mon = (value & 0xff) - 1; |
63 | |
64 | /* |
65 | * Read the minutes/seconds field again. If it changed since the first |
66 | * read, we can't assume that the values read so far are consistent, |
67 | * and should start from the beginning. |
68 | */ |
69 | res = regmap_read(map: rtc->ec->regmap, NTXEC_REG_READ_MINUTE_SECOND, val: &value); |
70 | if (res < 0) |
71 | return res; |
72 | |
73 | if (tm->tm_min != value >> 8 || tm->tm_sec != (value & 0xff)) |
74 | goto retry; |
75 | |
76 | return 0; |
77 | } |
78 | |
79 | static int ntxec_set_time(struct device *dev, struct rtc_time *tm) |
80 | { |
81 | struct ntxec_rtc *rtc = dev_get_drvdata(dev); |
82 | |
83 | /* |
84 | * To avoid time overflows while we're writing the full date/time, |
85 | * set the seconds field to zero before doing anything else. For the |
86 | * next 59 seconds (plus however long it takes until the RTC's next |
87 | * update of the second field), the seconds field will not overflow |
88 | * into the other fields. |
89 | */ |
90 | struct reg_sequence regs[] = { |
91 | { NTXEC_REG_WRITE_SECOND, ntxec_reg8(value: 0) }, |
92 | { NTXEC_REG_WRITE_YEAR, ntxec_reg8(value: tm->tm_year - 100) }, |
93 | { NTXEC_REG_WRITE_MONTH, ntxec_reg8(value: tm->tm_mon + 1) }, |
94 | { NTXEC_REG_WRITE_DAY, ntxec_reg8(value: tm->tm_mday) }, |
95 | { NTXEC_REG_WRITE_HOUR, ntxec_reg8(value: tm->tm_hour) }, |
96 | { NTXEC_REG_WRITE_MINUTE, ntxec_reg8(value: tm->tm_min) }, |
97 | { NTXEC_REG_WRITE_SECOND, ntxec_reg8(value: tm->tm_sec) }, |
98 | }; |
99 | |
100 | return regmap_multi_reg_write(map: rtc->ec->regmap, regs, ARRAY_SIZE(regs)); |
101 | } |
102 | |
103 | static const struct rtc_class_ops ntxec_rtc_ops = { |
104 | .read_time = ntxec_read_time, |
105 | .set_time = ntxec_set_time, |
106 | }; |
107 | |
108 | static int ntxec_rtc_probe(struct platform_device *pdev) |
109 | { |
110 | struct rtc_device *dev; |
111 | struct ntxec_rtc *rtc; |
112 | |
113 | pdev->dev.of_node = pdev->dev.parent->of_node; |
114 | |
115 | rtc = devm_kzalloc(dev: &pdev->dev, size: sizeof(*rtc), GFP_KERNEL); |
116 | if (!rtc) |
117 | return -ENOMEM; |
118 | |
119 | rtc->dev = &pdev->dev; |
120 | rtc->ec = dev_get_drvdata(dev: pdev->dev.parent); |
121 | platform_set_drvdata(pdev, data: rtc); |
122 | |
123 | dev = devm_rtc_allocate_device(dev: &pdev->dev); |
124 | if (IS_ERR(ptr: dev)) |
125 | return PTR_ERR(ptr: dev); |
126 | |
127 | dev->ops = &ntxec_rtc_ops; |
128 | dev->range_min = RTC_TIMESTAMP_BEGIN_2000; |
129 | dev->range_max = 9025257599LL; /* 2255-12-31 23:59:59 */ |
130 | |
131 | return devm_rtc_register_device(dev); |
132 | } |
133 | |
134 | static struct platform_driver ntxec_rtc_driver = { |
135 | .driver = { |
136 | .name = "ntxec-rtc" , |
137 | }, |
138 | .probe = ntxec_rtc_probe, |
139 | }; |
140 | module_platform_driver(ntxec_rtc_driver); |
141 | |
142 | MODULE_AUTHOR("Jonathan Neuschäfer <j.neuschaefer@gmx.net>" ); |
143 | MODULE_DESCRIPTION("RTC driver for Netronix EC" ); |
144 | MODULE_LICENSE("GPL" ); |
145 | MODULE_ALIAS("platform:ntxec-rtc" ); |
146 | |