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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>
1d98af87 19#include <linux/bcd.h>
8057c86d 20#include <linux/io.h>
1d98af87 21
68b54f47
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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)
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40#define M48T86_NVRAM(x) (0x0e + (x))
41#define M48T86_NVRAM_LEN 114
1d98af87 42
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43struct m48t86_rtc_info {
44 void __iomem *index_reg;
45 void __iomem *data_reg;
46 struct rtc_device *rtc;
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47};
48
49static 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
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54 writeb(addr, info->index_reg);
55 value = readb(info->data_reg);
56
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57 return value;
58}
59
60static 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
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65 writeb(addr, info->index_reg);
66 writeb(value, info->data_reg);
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67}
68
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69static int m48t86_rtc_read_time(struct device *dev, struct rtc_time *tm)
70{
71 unsigned char reg;
1d98af87 72
8057c86d 73 reg = m48t86_readb(dev, M48T86_B);
1d98af87 74
68b54f47 75 if (reg & M48T86_B_DM) {
1d98af87 76 /* data (binary) mode */
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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);
1d98af87 81 /* tm_mon is 0-11 */
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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);
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85 } else {
86 /* bcd mode */
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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));
1d98af87 92 /* tm_mon is 0-11 */
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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));
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96 }
97
98 /* correct the hour if the clock is in 12h mode */
68b54f47 99 if (!(reg & M48T86_B_H24))
8057c86d 100 if (m48t86_readb(dev, M48T86_HOUR) & 0x80)
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101 tm->tm_hour += 12;
102
52142ed4 103 return rtc_valid_tm(tm);
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104}
105
106static int m48t86_rtc_set_time(struct device *dev, struct rtc_time *tm)
107{
108 unsigned char reg;
1d98af87 109
8057c86d 110 reg = m48t86_readb(dev, M48T86_B);
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111
112 /* update flag and 24h mode */
68b54f47 113 reg |= M48T86_B_SET | M48T86_B_H24;
8057c86d 114 m48t86_writeb(dev, reg, M48T86_B);
1d98af87 115
68b54f47 116 if (reg & M48T86_B_DM) {
1d98af87 117 /* data (binary) mode */
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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);
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125 } else {
126 /* bcd mode */
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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);
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134 }
135
136 /* update ended */
68b54f47 137 reg &= ~M48T86_B_SET;
8057c86d 138 m48t86_writeb(dev, reg, M48T86_B);
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139
140 return 0;
141}
142
143static int m48t86_rtc_proc(struct device *dev, struct seq_file *seq)
144{
145 unsigned char reg;
1d98af87 146
8057c86d 147 reg = m48t86_readb(dev, M48T86_B);
1d98af87 148
1d98af87 149 seq_printf(seq, "mode\t\t: %s\n",
68b54f47 150 (reg & M48T86_B_DM) ? "binary" : "bcd");
1d98af87 151
8057c86d 152 reg = m48t86_readb(dev, M48T86_D);
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153
154 seq_printf(seq, "battery\t\t: %s\n",
68b54f47 155 (reg & M48T86_D_VRT) ? "ok" : "exhausted");
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156
157 return 0;
158}
159
ff8371ac 160static const struct rtc_class_ops m48t86_rtc_ops = {
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161 .read_time = m48t86_rtc_read_time,
162 .set_time = m48t86_rtc_set_time,
163 .proc = m48t86_rtc_proc,
164};
165
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166static ssize_t m48t86_nvram_read(struct file *filp, struct kobject *kobj,
167 struct bin_attribute *attr,
168 char *buf, loff_t off, size_t count)
169{
170 struct device *dev = kobj_to_dev(kobj);
171 unsigned int i;
172
173 for (i = 0; i < count; i++)
174 buf[i] = m48t86_readb(dev, M48T86_NVRAM(off + i));
175
176 return count;
177}
178
179static ssize_t m48t86_nvram_write(struct file *filp, struct kobject *kobj,
180 struct bin_attribute *attr,
181 char *buf, loff_t off, size_t count)
182{
183 struct device *dev = kobj_to_dev(kobj);
184 unsigned int i;
185
186 for (i = 0; i < count; i++)
187 m48t86_writeb(dev, buf[i], M48T86_NVRAM(off + i));
188
189 return count;
190}
191
192static BIN_ATTR(nvram, 0644, m48t86_nvram_read, m48t86_nvram_write,
193 M48T86_NVRAM_LEN);
194
3ea07127
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195/*
196 * The RTC is an optional feature at purchase time on some Technologic Systems
197 * boards. Verify that it actually exists by checking if the last two bytes
198 * of the NVRAM can be changed.
199 *
200 * This is based on the method used in their rtc7800.c example.
201 */
202static bool m48t86_verify_chip(struct platform_device *pdev)
203{
204 unsigned int offset0 = M48T86_NVRAM(M48T86_NVRAM_LEN - 2);
205 unsigned int offset1 = M48T86_NVRAM(M48T86_NVRAM_LEN - 1);
206 unsigned char tmp0, tmp1;
207
208 tmp0 = m48t86_readb(&pdev->dev, offset0);
209 tmp1 = m48t86_readb(&pdev->dev, offset1);
210
211 m48t86_writeb(&pdev->dev, 0x00, offset0);
212 m48t86_writeb(&pdev->dev, 0x55, offset1);
213 if (m48t86_readb(&pdev->dev, offset1) == 0x55) {
214 m48t86_writeb(&pdev->dev, 0xaa, offset1);
215 if (m48t86_readb(&pdev->dev, offset1) == 0xaa &&
216 m48t86_readb(&pdev->dev, offset0) == 0x00) {
217 m48t86_writeb(&pdev->dev, tmp0, offset0);
218 m48t86_writeb(&pdev->dev, tmp1, offset1);
219
220 return true;
221 }
222 }
223 return false;
224}
225
8057c86d 226static int m48t86_rtc_probe(struct platform_device *pdev)
1d98af87 227{
8057c86d 228 struct m48t86_rtc_info *info;
0500ce58 229 struct resource *res;
1d98af87 230 unsigned char reg;
d5b6bb0a 231
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232 info = devm_kzalloc(&pdev->dev, sizeof(*info), GFP_KERNEL);
233 if (!info)
234 return -ENOMEM;
235
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236 res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
237 if (!res)
238 return -ENODEV;
239 info->index_reg = devm_ioremap_resource(&pdev->dev, res);
240 if (IS_ERR(info->index_reg))
241 return PTR_ERR(info->index_reg);
242
243 res = platform_get_resource(pdev, IORESOURCE_MEM, 1);
244 if (!res)
245 return -ENODEV;
246 info->data_reg = devm_ioremap_resource(&pdev->dev, res);
247 if (IS_ERR(info->data_reg))
248 return PTR_ERR(info->data_reg);
1d98af87 249
8057c86d 250 dev_set_drvdata(&pdev->dev, info);
1d98af87 251
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252 if (!m48t86_verify_chip(pdev)) {
253 dev_info(&pdev->dev, "RTC not present\n");
254 return -ENODEV;
255 }
256
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257 info->rtc = devm_rtc_device_register(&pdev->dev, "m48t86",
258 &m48t86_rtc_ops, THIS_MODULE);
259 if (IS_ERR(info->rtc))
260 return PTR_ERR(info->rtc);
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261
262 /* read battery status */
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263 reg = m48t86_readb(&pdev->dev, M48T86_D);
264 dev_info(&pdev->dev, "battery %s\n",
68b54f47 265 (reg & M48T86_D_VRT) ? "ok" : "exhausted");
1d98af87 266
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267 if (device_create_bin_file(&pdev->dev, &bin_attr_nvram))
268 dev_err(&pdev->dev, "failed to create nvram sysfs entry\n");
269
270 return 0;
271}
272
273static int m48t86_rtc_remove(struct platform_device *pdev)
274{
275 device_remove_bin_file(&pdev->dev, &bin_attr_nvram);
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276 return 0;
277}
278
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279static struct platform_driver m48t86_rtc_platform_driver = {
280 .driver = {
281 .name = "rtc-m48t86",
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282 },
283 .probe = m48t86_rtc_probe,
b180cf8b 284 .remove = m48t86_rtc_remove,
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285};
286
0c4eae66 287module_platform_driver(m48t86_rtc_platform_driver);
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288
289MODULE_AUTHOR("Alessandro Zummo <a.zummo@towertech.it>");
290MODULE_DESCRIPTION("M48T86 RTC driver");
291MODULE_LICENSE("GPL");
ad28a07b 292MODULE_ALIAS("platform:rtc-m48t86");