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1 | /* | |
2 | * ST M48T86 / Dallas DS12887 RTC driver | |
3 | * Copyright (c) 2006 Tower Technologies | |
4 | * | |
5 | * Author: Alessandro Zummo <a.zummo@towertech.it> | |
6 | * | |
7 | * This program is free software; you can redistribute it and/or modify | |
8 | * it under the terms of the GNU General Public License version 2 as | |
9 | * published by the Free Software Foundation. | |
10 | * | |
11 | * This drivers only supports the clock running in BCD and 24H mode. | |
12 | * If it will be ever adapted to binary and 12H mode, care must be taken | |
13 | * to not introduce bugs. | |
14 | */ | |
15 | ||
16 | #include <linux/module.h> | |
17 | #include <linux/rtc.h> | |
18 | #include <linux/platform_device.h> | |
19 | #include <linux/bcd.h> | |
20 | #include <linux/io.h> | |
21 | ||
22 | #define M48T86_SEC 0x00 | |
23 | #define M48T86_SECALRM 0x01 | |
24 | #define M48T86_MIN 0x02 | |
25 | #define M48T86_MINALRM 0x03 | |
26 | #define M48T86_HOUR 0x04 | |
27 | #define M48T86_HOURALRM 0x05 | |
28 | #define M48T86_DOW 0x06 /* 1 = sunday */ | |
29 | #define M48T86_DOM 0x07 | |
30 | #define M48T86_MONTH 0x08 /* 1 - 12 */ | |
31 | #define M48T86_YEAR 0x09 /* 0 - 99 */ | |
32 | #define M48T86_A 0x0a | |
33 | #define M48T86_B 0x0b | |
34 | #define M48T86_B_SET BIT(7) | |
35 | #define M48T86_B_DM BIT(2) | |
36 | #define M48T86_B_H24 BIT(1) | |
37 | #define M48T86_C 0x0c | |
38 | #define M48T86_D 0x0d | |
39 | #define M48T86_D_VRT BIT(7) | |
40 | #define M48T86_NVRAM(x) (0x0e + (x)) | |
41 | #define M48T86_NVRAM_LEN 114 | |
42 | ||
43 | struct m48t86_rtc_info { | |
44 | void __iomem *index_reg; | |
45 | void __iomem *data_reg; | |
46 | struct rtc_device *rtc; | |
47 | }; | |
48 | ||
49 | static unsigned char m48t86_readb(struct device *dev, unsigned long addr) | |
50 | { | |
51 | struct m48t86_rtc_info *info = dev_get_drvdata(dev); | |
52 | unsigned char value; | |
53 | ||
54 | writeb(addr, info->index_reg); | |
55 | value = readb(info->data_reg); | |
56 | ||
57 | return value; | |
58 | } | |
59 | ||
60 | static void m48t86_writeb(struct device *dev, | |
61 | unsigned char value, unsigned long addr) | |
62 | { | |
63 | struct m48t86_rtc_info *info = dev_get_drvdata(dev); | |
64 | ||
65 | writeb(addr, info->index_reg); | |
66 | writeb(value, info->data_reg); | |
67 | } | |
68 | ||
69 | static int m48t86_rtc_read_time(struct device *dev, struct rtc_time *tm) | |
70 | { | |
71 | unsigned char reg; | |
72 | ||
73 | reg = m48t86_readb(dev, M48T86_B); | |
74 | ||
75 | if (reg & M48T86_B_DM) { | |
76 | /* data (binary) mode */ | |
77 | tm->tm_sec = m48t86_readb(dev, M48T86_SEC); | |
78 | tm->tm_min = m48t86_readb(dev, M48T86_MIN); | |
79 | tm->tm_hour = m48t86_readb(dev, M48T86_HOUR) & 0x3f; | |
80 | tm->tm_mday = m48t86_readb(dev, M48T86_DOM); | |
81 | /* tm_mon is 0-11 */ | |
82 | tm->tm_mon = m48t86_readb(dev, M48T86_MONTH) - 1; | |
83 | tm->tm_year = m48t86_readb(dev, M48T86_YEAR) + 100; | |
84 | tm->tm_wday = m48t86_readb(dev, M48T86_DOW); | |
85 | } else { | |
86 | /* bcd mode */ | |
87 | tm->tm_sec = bcd2bin(m48t86_readb(dev, M48T86_SEC)); | |
88 | tm->tm_min = bcd2bin(m48t86_readb(dev, M48T86_MIN)); | |
89 | tm->tm_hour = bcd2bin(m48t86_readb(dev, M48T86_HOUR) & | |
90 | 0x3f); | |
91 | tm->tm_mday = bcd2bin(m48t86_readb(dev, M48T86_DOM)); | |
92 | /* tm_mon is 0-11 */ | |
93 | tm->tm_mon = bcd2bin(m48t86_readb(dev, M48T86_MONTH)) - 1; | |
94 | tm->tm_year = bcd2bin(m48t86_readb(dev, M48T86_YEAR)) + 100; | |
95 | tm->tm_wday = bcd2bin(m48t86_readb(dev, M48T86_DOW)); | |
96 | } | |
97 | ||
98 | /* correct the hour if the clock is in 12h mode */ | |
99 | if (!(reg & M48T86_B_H24)) | |
100 | if (m48t86_readb(dev, M48T86_HOUR) & 0x80) | |
101 | tm->tm_hour += 12; | |
102 | ||
103 | return 0; | |
104 | } | |
105 | ||
106 | static int m48t86_rtc_set_time(struct device *dev, struct rtc_time *tm) | |
107 | { | |
108 | unsigned char reg; | |
109 | ||
110 | reg = m48t86_readb(dev, M48T86_B); | |
111 | ||
112 | /* update flag and 24h mode */ | |
113 | reg |= M48T86_B_SET | M48T86_B_H24; | |
114 | m48t86_writeb(dev, reg, M48T86_B); | |
115 | ||
116 | if (reg & M48T86_B_DM) { | |
117 | /* data (binary) mode */ | |
118 | m48t86_writeb(dev, tm->tm_sec, M48T86_SEC); | |
119 | m48t86_writeb(dev, tm->tm_min, M48T86_MIN); | |
120 | m48t86_writeb(dev, tm->tm_hour, M48T86_HOUR); | |
121 | m48t86_writeb(dev, tm->tm_mday, M48T86_DOM); | |
122 | m48t86_writeb(dev, tm->tm_mon + 1, M48T86_MONTH); | |
123 | m48t86_writeb(dev, tm->tm_year % 100, M48T86_YEAR); | |
124 | m48t86_writeb(dev, tm->tm_wday, M48T86_DOW); | |
125 | } else { | |
126 | /* bcd mode */ | |
127 | m48t86_writeb(dev, bin2bcd(tm->tm_sec), M48T86_SEC); | |
128 | m48t86_writeb(dev, bin2bcd(tm->tm_min), M48T86_MIN); | |
129 | m48t86_writeb(dev, bin2bcd(tm->tm_hour), M48T86_HOUR); | |
130 | m48t86_writeb(dev, bin2bcd(tm->tm_mday), M48T86_DOM); | |
131 | m48t86_writeb(dev, bin2bcd(tm->tm_mon + 1), M48T86_MONTH); | |
132 | m48t86_writeb(dev, bin2bcd(tm->tm_year % 100), M48T86_YEAR); | |
133 | m48t86_writeb(dev, bin2bcd(tm->tm_wday), M48T86_DOW); | |
134 | } | |
135 | ||
136 | /* update ended */ | |
137 | reg &= ~M48T86_B_SET; | |
138 | m48t86_writeb(dev, reg, M48T86_B); | |
139 | ||
140 | return 0; | |
141 | } | |
142 | ||
143 | static int m48t86_rtc_proc(struct device *dev, struct seq_file *seq) | |
144 | { | |
145 | unsigned char reg; | |
146 | ||
147 | reg = m48t86_readb(dev, M48T86_B); | |
148 | ||
149 | seq_printf(seq, "mode\t\t: %s\n", | |
150 | (reg & M48T86_B_DM) ? "binary" : "bcd"); | |
151 | ||
152 | reg = m48t86_readb(dev, M48T86_D); | |
153 | ||
154 | seq_printf(seq, "battery\t\t: %s\n", | |
155 | (reg & M48T86_D_VRT) ? "ok" : "exhausted"); | |
156 | ||
157 | return 0; | |
158 | } | |
159 | ||
160 | static const struct rtc_class_ops m48t86_rtc_ops = { | |
161 | .read_time = m48t86_rtc_read_time, | |
162 | .set_time = m48t86_rtc_set_time, | |
163 | .proc = m48t86_rtc_proc, | |
164 | }; | |
165 | ||
166 | static int m48t86_nvram_read(void *priv, unsigned int off, void *buf, | |
167 | size_t count) | |
168 | { | |
169 | struct device *dev = priv; | |
170 | unsigned int i; | |
171 | ||
172 | for (i = 0; i < count; i++) | |
173 | ((u8 *)buf)[i] = m48t86_readb(dev, M48T86_NVRAM(off + i)); | |
174 | ||
175 | return 0; | |
176 | } | |
177 | ||
178 | static int m48t86_nvram_write(void *priv, unsigned int off, void *buf, | |
179 | size_t count) | |
180 | { | |
181 | struct device *dev = priv; | |
182 | unsigned int i; | |
183 | ||
184 | for (i = 0; i < count; i++) | |
185 | m48t86_writeb(dev, ((u8 *)buf)[i], M48T86_NVRAM(off + i)); | |
186 | ||
187 | return 0; | |
188 | } | |
189 | ||
190 | /* | |
191 | * The RTC is an optional feature at purchase time on some Technologic Systems | |
192 | * boards. Verify that it actually exists by checking if the last two bytes | |
193 | * of the NVRAM can be changed. | |
194 | * | |
195 | * This is based on the method used in their rtc7800.c example. | |
196 | */ | |
197 | static bool m48t86_verify_chip(struct platform_device *pdev) | |
198 | { | |
199 | unsigned int offset0 = M48T86_NVRAM(M48T86_NVRAM_LEN - 2); | |
200 | unsigned int offset1 = M48T86_NVRAM(M48T86_NVRAM_LEN - 1); | |
201 | unsigned char tmp0, tmp1; | |
202 | ||
203 | tmp0 = m48t86_readb(&pdev->dev, offset0); | |
204 | tmp1 = m48t86_readb(&pdev->dev, offset1); | |
205 | ||
206 | m48t86_writeb(&pdev->dev, 0x00, offset0); | |
207 | m48t86_writeb(&pdev->dev, 0x55, offset1); | |
208 | if (m48t86_readb(&pdev->dev, offset1) == 0x55) { | |
209 | m48t86_writeb(&pdev->dev, 0xaa, offset1); | |
210 | if (m48t86_readb(&pdev->dev, offset1) == 0xaa && | |
211 | m48t86_readb(&pdev->dev, offset0) == 0x00) { | |
212 | m48t86_writeb(&pdev->dev, tmp0, offset0); | |
213 | m48t86_writeb(&pdev->dev, tmp1, offset1); | |
214 | ||
215 | return true; | |
216 | } | |
217 | } | |
218 | return false; | |
219 | } | |
220 | ||
221 | static int m48t86_rtc_probe(struct platform_device *pdev) | |
222 | { | |
223 | struct m48t86_rtc_info *info; | |
224 | struct resource *res; | |
225 | unsigned char reg; | |
226 | int err; | |
227 | struct nvmem_config m48t86_nvmem_cfg = { | |
228 | .name = "m48t86_nvram", | |
229 | .word_size = 1, | |
230 | .stride = 1, | |
231 | .size = M48T86_NVRAM_LEN, | |
232 | .reg_read = m48t86_nvram_read, | |
233 | .reg_write = m48t86_nvram_write, | |
234 | .priv = &pdev->dev, | |
235 | }; | |
236 | ||
237 | info = devm_kzalloc(&pdev->dev, sizeof(*info), GFP_KERNEL); | |
238 | if (!info) | |
239 | return -ENOMEM; | |
240 | ||
241 | res = platform_get_resource(pdev, IORESOURCE_MEM, 0); | |
242 | if (!res) | |
243 | return -ENODEV; | |
244 | info->index_reg = devm_ioremap_resource(&pdev->dev, res); | |
245 | if (IS_ERR(info->index_reg)) | |
246 | return PTR_ERR(info->index_reg); | |
247 | ||
248 | res = platform_get_resource(pdev, IORESOURCE_MEM, 1); | |
249 | if (!res) | |
250 | return -ENODEV; | |
251 | info->data_reg = devm_ioremap_resource(&pdev->dev, res); | |
252 | if (IS_ERR(info->data_reg)) | |
253 | return PTR_ERR(info->data_reg); | |
254 | ||
255 | dev_set_drvdata(&pdev->dev, info); | |
256 | ||
257 | if (!m48t86_verify_chip(pdev)) { | |
258 | dev_info(&pdev->dev, "RTC not present\n"); | |
259 | return -ENODEV; | |
260 | } | |
261 | ||
262 | info->rtc = devm_rtc_allocate_device(&pdev->dev); | |
263 | if (IS_ERR(info->rtc)) | |
264 | return PTR_ERR(info->rtc); | |
265 | ||
266 | info->rtc->ops = &m48t86_rtc_ops; | |
267 | info->rtc->nvram_old_abi = true; | |
268 | ||
269 | err = rtc_register_device(info->rtc); | |
270 | if (err) | |
271 | return err; | |
272 | ||
273 | rtc_nvmem_register(info->rtc, &m48t86_nvmem_cfg); | |
274 | ||
275 | /* read battery status */ | |
276 | reg = m48t86_readb(&pdev->dev, M48T86_D); | |
277 | dev_info(&pdev->dev, "battery %s\n", | |
278 | (reg & M48T86_D_VRT) ? "ok" : "exhausted"); | |
279 | ||
280 | return 0; | |
281 | } | |
282 | ||
283 | static struct platform_driver m48t86_rtc_platform_driver = { | |
284 | .driver = { | |
285 | .name = "rtc-m48t86", | |
286 | }, | |
287 | .probe = m48t86_rtc_probe, | |
288 | }; | |
289 | ||
290 | module_platform_driver(m48t86_rtc_platform_driver); | |
291 | ||
292 | MODULE_AUTHOR("Alessandro Zummo <a.zummo@towertech.it>"); | |
293 | MODULE_DESCRIPTION("M48T86 RTC driver"); | |
294 | MODULE_LICENSE("GPL"); | |
295 | MODULE_ALIAS("platform:rtc-m48t86"); |