1 | // SPDX-License-Identifier: GPL-2.0-only |
2 | /* |
3 | * Dallas DS1216 RTC driver |
4 | * |
5 | * Copyright (c) 2007 Thomas Bogendoerfer |
6 | * |
7 | */ |
8 | |
9 | #include <linux/module.h> |
10 | #include <linux/rtc.h> |
11 | #include <linux/platform_device.h> |
12 | #include <linux/bcd.h> |
13 | #include <linux/slab.h> |
14 | |
15 | struct ds1216_regs { |
16 | u8 tsec; |
17 | u8 sec; |
18 | u8 min; |
19 | u8 hour; |
20 | u8 wday; |
21 | u8 mday; |
22 | u8 month; |
23 | u8 year; |
24 | }; |
25 | |
26 | #define DS1216_HOUR_1224 (1 << 7) |
27 | #define DS1216_HOUR_AMPM (1 << 5) |
28 | |
29 | struct ds1216_priv { |
30 | struct rtc_device *rtc; |
31 | void __iomem *ioaddr; |
32 | }; |
33 | |
34 | static const u8 magic[] = { |
35 | 0xc5, 0x3a, 0xa3, 0x5c, 0xc5, 0x3a, 0xa3, 0x5c |
36 | }; |
37 | |
38 | /* |
39 | * Read the 64 bit we'd like to have - It a series |
40 | * of 64 bits showing up in the LSB of the base register. |
41 | * |
42 | */ |
43 | static void ds1216_read(u8 __iomem *ioaddr, u8 *buf) |
44 | { |
45 | unsigned char c; |
46 | int i, j; |
47 | |
48 | for (i = 0; i < 8; i++) { |
49 | c = 0; |
50 | for (j = 0; j < 8; j++) |
51 | c |= (readb(ioaddr) & 0x1) << j; |
52 | buf[i] = c; |
53 | } |
54 | } |
55 | |
56 | static void ds1216_write(u8 __iomem *ioaddr, const u8 *buf) |
57 | { |
58 | unsigned char c; |
59 | int i, j; |
60 | |
61 | for (i = 0; i < 8; i++) { |
62 | c = buf[i]; |
63 | for (j = 0; j < 8; j++) { |
64 | writeb(c, ioaddr); |
65 | c = c >> 1; |
66 | } |
67 | } |
68 | } |
69 | |
70 | static void ds1216_switch_ds_to_clock(u8 __iomem *ioaddr) |
71 | { |
72 | /* Reset magic pointer */ |
73 | readb(ioaddr); |
74 | /* Write 64 bit magic to DS1216 */ |
75 | ds1216_write(ioaddr, buf: magic); |
76 | } |
77 | |
78 | static int ds1216_rtc_read_time(struct device *dev, struct rtc_time *tm) |
79 | { |
80 | struct ds1216_priv *priv = dev_get_drvdata(dev); |
81 | struct ds1216_regs regs; |
82 | |
83 | ds1216_switch_ds_to_clock(ioaddr: priv->ioaddr); |
84 | ds1216_read(ioaddr: priv->ioaddr, buf: (u8 *)®s); |
85 | |
86 | tm->tm_sec = bcd2bin(regs.sec); |
87 | tm->tm_min = bcd2bin(regs.min); |
88 | if (regs.hour & DS1216_HOUR_1224) { |
89 | /* AM/PM mode */ |
90 | tm->tm_hour = bcd2bin(regs.hour & 0x1f); |
91 | if (regs.hour & DS1216_HOUR_AMPM) |
92 | tm->tm_hour += 12; |
93 | } else |
94 | tm->tm_hour = bcd2bin(regs.hour & 0x3f); |
95 | tm->tm_wday = (regs.wday & 7) - 1; |
96 | tm->tm_mday = bcd2bin(regs.mday & 0x3f); |
97 | tm->tm_mon = bcd2bin(regs.month & 0x1f); |
98 | tm->tm_year = bcd2bin(regs.year); |
99 | if (tm->tm_year < 70) |
100 | tm->tm_year += 100; |
101 | |
102 | return 0; |
103 | } |
104 | |
105 | static int ds1216_rtc_set_time(struct device *dev, struct rtc_time *tm) |
106 | { |
107 | struct ds1216_priv *priv = dev_get_drvdata(dev); |
108 | struct ds1216_regs regs; |
109 | |
110 | ds1216_switch_ds_to_clock(ioaddr: priv->ioaddr); |
111 | ds1216_read(ioaddr: priv->ioaddr, buf: (u8 *)®s); |
112 | |
113 | regs.tsec = 0; /* clear 0.1 and 0.01 seconds */ |
114 | regs.sec = bin2bcd(tm->tm_sec); |
115 | regs.min = bin2bcd(tm->tm_min); |
116 | regs.hour &= DS1216_HOUR_1224; |
117 | if (regs.hour && tm->tm_hour > 12) { |
118 | regs.hour |= DS1216_HOUR_AMPM; |
119 | tm->tm_hour -= 12; |
120 | } |
121 | regs.hour |= bin2bcd(tm->tm_hour); |
122 | regs.wday &= ~7; |
123 | regs.wday |= tm->tm_wday; |
124 | regs.mday = bin2bcd(tm->tm_mday); |
125 | regs.month = bin2bcd(tm->tm_mon); |
126 | regs.year = bin2bcd(tm->tm_year % 100); |
127 | |
128 | ds1216_switch_ds_to_clock(ioaddr: priv->ioaddr); |
129 | ds1216_write(ioaddr: priv->ioaddr, buf: (u8 *)®s); |
130 | return 0; |
131 | } |
132 | |
133 | static const struct rtc_class_ops ds1216_rtc_ops = { |
134 | .read_time = ds1216_rtc_read_time, |
135 | .set_time = ds1216_rtc_set_time, |
136 | }; |
137 | |
138 | static int __init ds1216_rtc_probe(struct platform_device *pdev) |
139 | { |
140 | struct ds1216_priv *priv; |
141 | u8 dummy[8]; |
142 | |
143 | priv = devm_kzalloc(dev: &pdev->dev, size: sizeof(*priv), GFP_KERNEL); |
144 | if (!priv) |
145 | return -ENOMEM; |
146 | |
147 | platform_set_drvdata(pdev, data: priv); |
148 | |
149 | priv->ioaddr = devm_platform_ioremap_resource(pdev, index: 0); |
150 | if (IS_ERR(ptr: priv->ioaddr)) |
151 | return PTR_ERR(ptr: priv->ioaddr); |
152 | |
153 | priv->rtc = devm_rtc_device_register(dev: &pdev->dev, name: "ds1216" , |
154 | ops: &ds1216_rtc_ops, THIS_MODULE); |
155 | if (IS_ERR(ptr: priv->rtc)) |
156 | return PTR_ERR(ptr: priv->rtc); |
157 | |
158 | /* dummy read to get clock into a known state */ |
159 | ds1216_read(ioaddr: priv->ioaddr, buf: dummy); |
160 | return 0; |
161 | } |
162 | |
163 | static struct platform_driver ds1216_rtc_platform_driver = { |
164 | .driver = { |
165 | .name = "rtc-ds1216" , |
166 | }, |
167 | }; |
168 | |
169 | module_platform_driver_probe(ds1216_rtc_platform_driver, ds1216_rtc_probe); |
170 | |
171 | MODULE_AUTHOR("Thomas Bogendoerfer <tsbogend@alpha.franken.de>" ); |
172 | MODULE_DESCRIPTION("DS1216 RTC driver" ); |
173 | MODULE_LICENSE("GPL" ); |
174 | MODULE_ALIAS("platform:rtc-ds1216" ); |
175 | |