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13#include <linux/module.h>
14#include <linux/rtc.h>
15#include <linux/platform_device.h>
16#include <linux/bcd.h>
17#include <linux/io.h>
18
19#define M48T86_SEC 0x00
20#define M48T86_SECALRM 0x01
21#define M48T86_MIN 0x02
22#define M48T86_MINALRM 0x03
23#define M48T86_HOUR 0x04
24#define M48T86_HOURALRM 0x05
25#define M48T86_DOW 0x06
26#define M48T86_DOM 0x07
27#define M48T86_MONTH 0x08
28#define M48T86_YEAR 0x09
29#define M48T86_A 0x0a
30#define M48T86_B 0x0b
31#define M48T86_B_SET BIT(7)
32#define M48T86_B_DM BIT(2)
33#define M48T86_B_H24 BIT(1)
34#define M48T86_C 0x0c
35#define M48T86_D 0x0d
36#define M48T86_D_VRT BIT(7)
37#define M48T86_NVRAM(x) (0x0e + (x))
38#define M48T86_NVRAM_LEN 114
39
40struct m48t86_rtc_info {
41 void __iomem *index_reg;
42 void __iomem *data_reg;
43 struct rtc_device *rtc;
44};
45
46static unsigned char m48t86_readb(struct device *dev, unsigned long addr)
47{
48 struct m48t86_rtc_info *info = dev_get_drvdata(dev);
49 unsigned char value;
50
51 writeb(addr, info->index_reg);
52 value = readb(info->data_reg);
53
54 return value;
55}
56
57static void m48t86_writeb(struct device *dev,
58 unsigned char value, unsigned long addr)
59{
60 struct m48t86_rtc_info *info = dev_get_drvdata(dev);
61
62 writeb(addr, info->index_reg);
63 writeb(value, info->data_reg);
64}
65
66static int m48t86_rtc_read_time(struct device *dev, struct rtc_time *tm)
67{
68 unsigned char reg;
69
70 reg = m48t86_readb(dev, M48T86_B);
71
72 if (reg & M48T86_B_DM) {
73
74 tm->tm_sec = m48t86_readb(dev, M48T86_SEC);
75 tm->tm_min = m48t86_readb(dev, M48T86_MIN);
76 tm->tm_hour = m48t86_readb(dev, M48T86_HOUR) & 0x3f;
77 tm->tm_mday = m48t86_readb(dev, M48T86_DOM);
78
79 tm->tm_mon = m48t86_readb(dev, M48T86_MONTH) - 1;
80 tm->tm_year = m48t86_readb(dev, M48T86_YEAR) + 100;
81 tm->tm_wday = m48t86_readb(dev, M48T86_DOW);
82 } else {
83
84 tm->tm_sec = bcd2bin(m48t86_readb(dev, M48T86_SEC));
85 tm->tm_min = bcd2bin(m48t86_readb(dev, M48T86_MIN));
86 tm->tm_hour = bcd2bin(m48t86_readb(dev, M48T86_HOUR) &
87 0x3f);
88 tm->tm_mday = bcd2bin(m48t86_readb(dev, M48T86_DOM));
89
90 tm->tm_mon = bcd2bin(m48t86_readb(dev, M48T86_MONTH)) - 1;
91 tm->tm_year = bcd2bin(m48t86_readb(dev, M48T86_YEAR)) + 100;
92 tm->tm_wday = bcd2bin(m48t86_readb(dev, M48T86_DOW));
93 }
94
95
96 if (!(reg & M48T86_B_H24))
97 if (m48t86_readb(dev, M48T86_HOUR) & 0x80)
98 tm->tm_hour += 12;
99
100 return 0;
101}
102
103static int m48t86_rtc_set_time(struct device *dev, struct rtc_time *tm)
104{
105 unsigned char reg;
106
107 reg = m48t86_readb(dev, M48T86_B);
108
109
110 reg |= M48T86_B_SET | M48T86_B_H24;
111 m48t86_writeb(dev, reg, M48T86_B);
112
113 if (reg & M48T86_B_DM) {
114
115 m48t86_writeb(dev, tm->tm_sec, M48T86_SEC);
116 m48t86_writeb(dev, tm->tm_min, M48T86_MIN);
117 m48t86_writeb(dev, tm->tm_hour, M48T86_HOUR);
118 m48t86_writeb(dev, tm->tm_mday, M48T86_DOM);
119 m48t86_writeb(dev, tm->tm_mon + 1, M48T86_MONTH);
120 m48t86_writeb(dev, tm->tm_year % 100, M48T86_YEAR);
121 m48t86_writeb(dev, tm->tm_wday, M48T86_DOW);
122 } else {
123
124 m48t86_writeb(dev, bin2bcd(tm->tm_sec), M48T86_SEC);
125 m48t86_writeb(dev, bin2bcd(tm->tm_min), M48T86_MIN);
126 m48t86_writeb(dev, bin2bcd(tm->tm_hour), M48T86_HOUR);
127 m48t86_writeb(dev, bin2bcd(tm->tm_mday), M48T86_DOM);
128 m48t86_writeb(dev, bin2bcd(tm->tm_mon + 1), M48T86_MONTH);
129 m48t86_writeb(dev, bin2bcd(tm->tm_year % 100), M48T86_YEAR);
130 m48t86_writeb(dev, bin2bcd(tm->tm_wday), M48T86_DOW);
131 }
132
133
134 reg &= ~M48T86_B_SET;
135 m48t86_writeb(dev, reg, M48T86_B);
136
137 return 0;
138}
139
140static int m48t86_rtc_proc(struct device *dev, struct seq_file *seq)
141{
142 unsigned char reg;
143
144 reg = m48t86_readb(dev, M48T86_B);
145
146 seq_printf(seq, "mode\t\t: %s\n",
147 (reg & M48T86_B_DM) ? "binary" : "bcd");
148
149 reg = m48t86_readb(dev, M48T86_D);
150
151 seq_printf(seq, "battery\t\t: %s\n",
152 (reg & M48T86_D_VRT) ? "ok" : "exhausted");
153
154 return 0;
155}
156
157static const struct rtc_class_ops m48t86_rtc_ops = {
158 .read_time = m48t86_rtc_read_time,
159 .set_time = m48t86_rtc_set_time,
160 .proc = m48t86_rtc_proc,
161};
162
163static int m48t86_nvram_read(void *priv, unsigned int off, void *buf,
164 size_t count)
165{
166 struct device *dev = priv;
167 unsigned int i;
168
169 for (i = 0; i < count; i++)
170 ((u8 *)buf)[i] = m48t86_readb(dev, M48T86_NVRAM(off + i));
171
172 return 0;
173}
174
175static int m48t86_nvram_write(void *priv, unsigned int off, void *buf,
176 size_t count)
177{
178 struct device *dev = priv;
179 unsigned int i;
180
181 for (i = 0; i < count; i++)
182 m48t86_writeb(dev, ((u8 *)buf)[i], M48T86_NVRAM(off + i));
183
184 return 0;
185}
186
187
188
189
190
191
192
193
194static bool m48t86_verify_chip(struct platform_device *pdev)
195{
196 unsigned int offset0 = M48T86_NVRAM(M48T86_NVRAM_LEN - 2);
197 unsigned int offset1 = M48T86_NVRAM(M48T86_NVRAM_LEN - 1);
198 unsigned char tmp0, tmp1;
199
200 tmp0 = m48t86_readb(&pdev->dev, offset0);
201 tmp1 = m48t86_readb(&pdev->dev, offset1);
202
203 m48t86_writeb(&pdev->dev, 0x00, offset0);
204 m48t86_writeb(&pdev->dev, 0x55, offset1);
205 if (m48t86_readb(&pdev->dev, offset1) == 0x55) {
206 m48t86_writeb(&pdev->dev, 0xaa, offset1);
207 if (m48t86_readb(&pdev->dev, offset1) == 0xaa &&
208 m48t86_readb(&pdev->dev, offset0) == 0x00) {
209 m48t86_writeb(&pdev->dev, tmp0, offset0);
210 m48t86_writeb(&pdev->dev, tmp1, offset1);
211
212 return true;
213 }
214 }
215 return false;
216}
217
218static int m48t86_rtc_probe(struct platform_device *pdev)
219{
220 struct m48t86_rtc_info *info;
221 unsigned char reg;
222 int err;
223 struct nvmem_config m48t86_nvmem_cfg = {
224 .name = "m48t86_nvram",
225 .word_size = 1,
226 .stride = 1,
227 .size = M48T86_NVRAM_LEN,
228 .reg_read = m48t86_nvram_read,
229 .reg_write = m48t86_nvram_write,
230 .priv = &pdev->dev,
231 };
232
233 info = devm_kzalloc(&pdev->dev, sizeof(*info), GFP_KERNEL);
234 if (!info)
235 return -ENOMEM;
236
237 info->index_reg = devm_platform_ioremap_resource(pdev, 0);
238 if (IS_ERR(info->index_reg))
239 return PTR_ERR(info->index_reg);
240
241 info->data_reg = devm_platform_ioremap_resource(pdev, 1);
242 if (IS_ERR(info->data_reg))
243 return PTR_ERR(info->data_reg);
244
245 dev_set_drvdata(&pdev->dev, info);
246
247 if (!m48t86_verify_chip(pdev)) {
248 dev_info(&pdev->dev, "RTC not present\n");
249 return -ENODEV;
250 }
251
252 info->rtc = devm_rtc_allocate_device(&pdev->dev);
253 if (IS_ERR(info->rtc))
254 return PTR_ERR(info->rtc);
255
256 info->rtc->ops = &m48t86_rtc_ops;
257
258 err = devm_rtc_register_device(info->rtc);
259 if (err)
260 return err;
261
262 devm_rtc_nvmem_register(info->rtc, &m48t86_nvmem_cfg);
263
264
265 reg = m48t86_readb(&pdev->dev, M48T86_D);
266 dev_info(&pdev->dev, "battery %s\n",
267 (reg & M48T86_D_VRT) ? "ok" : "exhausted");
268
269 return 0;
270}
271
272static struct platform_driver m48t86_rtc_platform_driver = {
273 .driver = {
274 .name = "rtc-m48t86",
275 },
276 .probe = m48t86_rtc_probe,
277};
278
279module_platform_driver(m48t86_rtc_platform_driver);
280
281MODULE_AUTHOR("Alessandro Zummo <a.zummo@towertech.it>");
282MODULE_DESCRIPTION("M48T86 RTC driver");
283MODULE_LICENSE("GPL");
284MODULE_ALIAS("platform:rtc-m48t86");
285
