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74d34d4b VN |
1 | /* |
2 | * | |
3 | * Driver for ST M41T93 SPI RTC | |
4 | * | |
5 | * (c) 2010 Nikolaus Voss, Weinmann Medical GmbH | |
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 | ||
12 | #include <linux/bcd.h> | |
13 | #include <linux/kernel.h> | |
14 | #include <linux/module.h> | |
15 | #include <linux/platform_device.h> | |
16 | #include <linux/rtc.h> | |
17 | #include <linux/spi/spi.h> | |
18 | ||
19 | #define M41T93_REG_SSEC 0 | |
20 | #define M41T93_REG_ST_SEC 1 | |
21 | #define M41T93_REG_MIN 2 | |
22 | #define M41T93_REG_CENT_HOUR 3 | |
23 | #define M41T93_REG_WDAY 4 | |
24 | #define M41T93_REG_DAY 5 | |
25 | #define M41T93_REG_MON 6 | |
26 | #define M41T93_REG_YEAR 7 | |
27 | ||
28 | ||
29 | #define M41T93_REG_ALM_HOUR_HT 0xc | |
30 | #define M41T93_REG_FLAGS 0xf | |
31 | ||
32 | #define M41T93_FLAG_ST (1 << 7) | |
33 | #define M41T93_FLAG_OF (1 << 2) | |
34 | #define M41T93_FLAG_BL (1 << 4) | |
35 | #define M41T93_FLAG_HT (1 << 6) | |
36 | ||
37 | static inline int m41t93_set_reg(struct spi_device *spi, u8 addr, u8 data) | |
38 | { | |
39 | u8 buf[2]; | |
40 | ||
41 | /* MSB must be '1' to write */ | |
42 | buf[0] = addr | 0x80; | |
43 | buf[1] = data; | |
44 | ||
45 | return spi_write(spi, buf, sizeof(buf)); | |
46 | } | |
47 | ||
48 | static int m41t93_set_time(struct device *dev, struct rtc_time *tm) | |
49 | { | |
50 | struct spi_device *spi = to_spi_device(dev); | |
51 | u8 buf[9] = {0x80}; /* write cmd + 8 data bytes */ | |
52 | u8 * const data = &buf[1]; /* ptr to first data byte */ | |
53 | ||
54 | dev_dbg(dev, "%s secs=%d, mins=%d, " | |
55 | "hours=%d, mday=%d, mon=%d, year=%d, wday=%d\n", | |
56 | "write", tm->tm_sec, tm->tm_min, | |
57 | tm->tm_hour, tm->tm_mday, | |
58 | tm->tm_mon, tm->tm_year, tm->tm_wday); | |
59 | ||
60 | if (tm->tm_year < 100) { | |
61 | dev_warn(&spi->dev, "unsupported date (before 2000-01-01).\n"); | |
62 | return -EINVAL; | |
63 | } | |
64 | ||
65 | data[M41T93_REG_SSEC] = 0; | |
66 | data[M41T93_REG_ST_SEC] = bin2bcd(tm->tm_sec); | |
67 | data[M41T93_REG_MIN] = bin2bcd(tm->tm_min); | |
68 | data[M41T93_REG_CENT_HOUR] = bin2bcd(tm->tm_hour) | | |
69 | ((tm->tm_year/100-1) << 6); | |
70 | data[M41T93_REG_DAY] = bin2bcd(tm->tm_mday); | |
71 | data[M41T93_REG_WDAY] = bin2bcd(tm->tm_wday + 1); | |
72 | data[M41T93_REG_MON] = bin2bcd(tm->tm_mon + 1); | |
73 | data[M41T93_REG_YEAR] = bin2bcd(tm->tm_year % 100); | |
74 | ||
75 | return spi_write(spi, buf, sizeof(buf)); | |
76 | } | |
77 | ||
78 | ||
79 | static int m41t93_get_time(struct device *dev, struct rtc_time *tm) | |
80 | { | |
81 | struct spi_device *spi = to_spi_device(dev); | |
82 | const u8 start_addr = 0; | |
83 | u8 buf[8]; | |
84 | int century_after_1900; | |
85 | int tmp; | |
86 | int ret = 0; | |
87 | ||
88 | /* Check status of clock. Two states must be considered: | |
89 | 1. halt bit (HT) is set: the clock is running but update of readout | |
90 | registers has been disabled due to power failure. This is normal | |
91 | case after poweron. Time is valid after resetting HT bit. | |
92 | 2. oscillator fail bit (OF) is set. Oscillator has be stopped and | |
93 | time is invalid: | |
94 | a) OF can be immeditely reset. | |
95 | b) OF cannot be immediately reset: oscillator has to be restarted. | |
96 | */ | |
97 | tmp = spi_w8r8(spi, M41T93_REG_ALM_HOUR_HT); | |
98 | if (tmp < 0) | |
99 | return tmp; | |
100 | ||
101 | if (tmp & M41T93_FLAG_HT) { | |
102 | dev_dbg(&spi->dev, "HT bit is set, reenable clock update.\n"); | |
103 | m41t93_set_reg(spi, M41T93_REG_ALM_HOUR_HT, | |
104 | tmp & ~M41T93_FLAG_HT); | |
105 | } | |
106 | ||
107 | tmp = spi_w8r8(spi, M41T93_REG_FLAGS); | |
108 | if (tmp < 0) | |
109 | return tmp; | |
110 | ||
111 | if (tmp & M41T93_FLAG_OF) { | |
112 | ret = -EINVAL; | |
113 | dev_warn(&spi->dev, "OF bit is set, resetting.\n"); | |
114 | m41t93_set_reg(spi, M41T93_REG_FLAGS, tmp & ~M41T93_FLAG_OF); | |
115 | ||
116 | tmp = spi_w8r8(spi, M41T93_REG_FLAGS); | |
117 | if (tmp < 0) | |
118 | return tmp; | |
119 | else if (tmp & M41T93_FLAG_OF) { | |
120 | u8 reset_osc = buf[M41T93_REG_ST_SEC] | M41T93_FLAG_ST; | |
121 | ||
122 | dev_warn(&spi->dev, | |
123 | "OF bit is still set, kickstarting clock.\n"); | |
124 | m41t93_set_reg(spi, M41T93_REG_ST_SEC, reset_osc); | |
125 | reset_osc &= ~M41T93_FLAG_ST; | |
126 | m41t93_set_reg(spi, M41T93_REG_ST_SEC, reset_osc); | |
127 | } | |
128 | } | |
129 | ||
130 | if (tmp & M41T93_FLAG_BL) | |
131 | dev_warn(&spi->dev, "BL bit is set, replace battery.\n"); | |
132 | ||
133 | /* read actual time/date */ | |
134 | tmp = spi_write_then_read(spi, &start_addr, 1, buf, sizeof(buf)); | |
135 | if (tmp < 0) | |
136 | return tmp; | |
137 | ||
138 | tm->tm_sec = bcd2bin(buf[M41T93_REG_ST_SEC]); | |
139 | tm->tm_min = bcd2bin(buf[M41T93_REG_MIN]); | |
140 | tm->tm_hour = bcd2bin(buf[M41T93_REG_CENT_HOUR] & 0x3f); | |
141 | tm->tm_mday = bcd2bin(buf[M41T93_REG_DAY]); | |
142 | tm->tm_mon = bcd2bin(buf[M41T93_REG_MON]) - 1; | |
143 | tm->tm_wday = bcd2bin(buf[M41T93_REG_WDAY] & 0x0f) - 1; | |
144 | ||
145 | century_after_1900 = (buf[M41T93_REG_CENT_HOUR] >> 6) + 1; | |
146 | tm->tm_year = bcd2bin(buf[M41T93_REG_YEAR]) + century_after_1900 * 100; | |
147 | ||
148 | dev_dbg(dev, "%s secs=%d, mins=%d, " | |
149 | "hours=%d, mday=%d, mon=%d, year=%d, wday=%d\n", | |
150 | "read", tm->tm_sec, tm->tm_min, | |
151 | tm->tm_hour, tm->tm_mday, | |
152 | tm->tm_mon, tm->tm_year, tm->tm_wday); | |
153 | ||
154 | return ret < 0 ? ret : rtc_valid_tm(tm); | |
155 | } | |
156 | ||
157 | ||
158 | static const struct rtc_class_ops m41t93_rtc_ops = { | |
159 | .read_time = m41t93_get_time, | |
160 | .set_time = m41t93_set_time, | |
161 | }; | |
162 | ||
163 | static struct spi_driver m41t93_driver; | |
164 | ||
165 | static int __devinit m41t93_probe(struct spi_device *spi) | |
166 | { | |
167 | struct rtc_device *rtc; | |
168 | int res; | |
169 | ||
170 | spi->bits_per_word = 8; | |
171 | spi_setup(spi); | |
172 | ||
173 | res = spi_w8r8(spi, M41T93_REG_WDAY); | |
174 | if (res < 0 || (res & 0xf8) != 0) { | |
175 | dev_err(&spi->dev, "not found 0x%x.\n", res); | |
176 | return -ENODEV; | |
177 | } | |
178 | ||
179 | rtc = rtc_device_register(m41t93_driver.driver.name, | |
180 | &spi->dev, &m41t93_rtc_ops, THIS_MODULE); | |
181 | if (IS_ERR(rtc)) | |
182 | return PTR_ERR(rtc); | |
183 | ||
184 | dev_set_drvdata(&spi->dev, rtc); | |
185 | ||
186 | return 0; | |
187 | } | |
188 | ||
189 | ||
190 | static int __devexit m41t93_remove(struct spi_device *spi) | |
191 | { | |
a80fd9db | 192 | struct rtc_device *rtc = spi_get_drvdata(spi); |
74d34d4b VN |
193 | |
194 | if (rtc) | |
195 | rtc_device_unregister(rtc); | |
196 | ||
197 | return 0; | |
198 | } | |
199 | ||
200 | static struct spi_driver m41t93_driver = { | |
201 | .driver = { | |
202 | .name = "rtc-m41t93", | |
203 | .bus = &spi_bus_type, | |
204 | .owner = THIS_MODULE, | |
205 | }, | |
206 | .probe = m41t93_probe, | |
207 | .remove = __devexit_p(m41t93_remove), | |
208 | }; | |
209 | ||
210 | static __init int m41t93_init(void) | |
211 | { | |
212 | return spi_register_driver(&m41t93_driver); | |
213 | } | |
214 | module_init(m41t93_init); | |
215 | ||
216 | static __exit void m41t93_exit(void) | |
217 | { | |
218 | spi_unregister_driver(&m41t93_driver); | |
219 | } | |
220 | module_exit(m41t93_exit); | |
221 | ||
222 | MODULE_AUTHOR("Nikolaus Voss <n.voss@weinmann.de>"); | |
223 | MODULE_DESCRIPTION("Driver for ST M41T93 SPI RTC"); | |
224 | MODULE_LICENSE("GPL"); | |
225 | MODULE_ALIAS("spi:rtc-m41t93"); |