]>
Commit | Line | Data |
---|---|---|
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); | |
bcffb10f | 51 | int tmp; |
74d34d4b VN |
52 | u8 buf[9] = {0x80}; /* write cmd + 8 data bytes */ |
53 | u8 * const data = &buf[1]; /* ptr to first data byte */ | |
54 | ||
55 | dev_dbg(dev, "%s secs=%d, mins=%d, " | |
56 | "hours=%d, mday=%d, mon=%d, year=%d, wday=%d\n", | |
57 | "write", tm->tm_sec, tm->tm_min, | |
58 | tm->tm_hour, tm->tm_mday, | |
59 | tm->tm_mon, tm->tm_year, tm->tm_wday); | |
60 | ||
61 | if (tm->tm_year < 100) { | |
62 | dev_warn(&spi->dev, "unsupported date (before 2000-01-01).\n"); | |
63 | return -EINVAL; | |
64 | } | |
65 | ||
bcffb10f NV |
66 | tmp = spi_w8r8(spi, M41T93_REG_FLAGS); |
67 | if (tmp < 0) | |
68 | return tmp; | |
69 | ||
70 | if (tmp & M41T93_FLAG_OF) { | |
71 | dev_warn(&spi->dev, "OF bit is set, resetting.\n"); | |
72 | m41t93_set_reg(spi, M41T93_REG_FLAGS, tmp & ~M41T93_FLAG_OF); | |
73 | ||
74 | tmp = spi_w8r8(spi, M41T93_REG_FLAGS); | |
75 | if (tmp < 0) { | |
76 | return tmp; | |
77 | } else if (tmp & M41T93_FLAG_OF) { | |
78 | /* OF cannot be immediately reset: oscillator has to be | |
79 | * restarted. */ | |
80 | u8 reset_osc = buf[M41T93_REG_ST_SEC] | M41T93_FLAG_ST; | |
81 | ||
82 | dev_warn(&spi->dev, | |
83 | "OF bit is still set, kickstarting clock.\n"); | |
84 | m41t93_set_reg(spi, M41T93_REG_ST_SEC, reset_osc); | |
85 | reset_osc &= ~M41T93_FLAG_ST; | |
86 | m41t93_set_reg(spi, M41T93_REG_ST_SEC, reset_osc); | |
87 | } | |
88 | } | |
89 | ||
74d34d4b VN |
90 | data[M41T93_REG_SSEC] = 0; |
91 | data[M41T93_REG_ST_SEC] = bin2bcd(tm->tm_sec); | |
92 | data[M41T93_REG_MIN] = bin2bcd(tm->tm_min); | |
93 | data[M41T93_REG_CENT_HOUR] = bin2bcd(tm->tm_hour) | | |
94 | ((tm->tm_year/100-1) << 6); | |
95 | data[M41T93_REG_DAY] = bin2bcd(tm->tm_mday); | |
96 | data[M41T93_REG_WDAY] = bin2bcd(tm->tm_wday + 1); | |
97 | data[M41T93_REG_MON] = bin2bcd(tm->tm_mon + 1); | |
98 | data[M41T93_REG_YEAR] = bin2bcd(tm->tm_year % 100); | |
99 | ||
100 | return spi_write(spi, buf, sizeof(buf)); | |
101 | } | |
102 | ||
103 | ||
104 | static int m41t93_get_time(struct device *dev, struct rtc_time *tm) | |
105 | { | |
106 | struct spi_device *spi = to_spi_device(dev); | |
107 | const u8 start_addr = 0; | |
108 | u8 buf[8]; | |
109 | int century_after_1900; | |
110 | int tmp; | |
111 | int ret = 0; | |
112 | ||
113 | /* Check status of clock. Two states must be considered: | |
114 | 1. halt bit (HT) is set: the clock is running but update of readout | |
115 | registers has been disabled due to power failure. This is normal | |
116 | case after poweron. Time is valid after resetting HT bit. | |
bcffb10f | 117 | 2. oscillator fail bit (OF) is set: time is invalid. |
74d34d4b VN |
118 | */ |
119 | tmp = spi_w8r8(spi, M41T93_REG_ALM_HOUR_HT); | |
120 | if (tmp < 0) | |
121 | return tmp; | |
122 | ||
123 | if (tmp & M41T93_FLAG_HT) { | |
124 | dev_dbg(&spi->dev, "HT bit is set, reenable clock update.\n"); | |
125 | m41t93_set_reg(spi, M41T93_REG_ALM_HOUR_HT, | |
126 | tmp & ~M41T93_FLAG_HT); | |
127 | } | |
128 | ||
129 | tmp = spi_w8r8(spi, M41T93_REG_FLAGS); | |
130 | if (tmp < 0) | |
131 | return tmp; | |
132 | ||
133 | if (tmp & M41T93_FLAG_OF) { | |
134 | ret = -EINVAL; | |
bcffb10f | 135 | dev_warn(&spi->dev, "OF bit is set, write time to restart.\n"); |
74d34d4b VN |
136 | } |
137 | ||
138 | if (tmp & M41T93_FLAG_BL) | |
139 | dev_warn(&spi->dev, "BL bit is set, replace battery.\n"); | |
140 | ||
141 | /* read actual time/date */ | |
142 | tmp = spi_write_then_read(spi, &start_addr, 1, buf, sizeof(buf)); | |
143 | if (tmp < 0) | |
144 | return tmp; | |
145 | ||
146 | tm->tm_sec = bcd2bin(buf[M41T93_REG_ST_SEC]); | |
147 | tm->tm_min = bcd2bin(buf[M41T93_REG_MIN]); | |
148 | tm->tm_hour = bcd2bin(buf[M41T93_REG_CENT_HOUR] & 0x3f); | |
149 | tm->tm_mday = bcd2bin(buf[M41T93_REG_DAY]); | |
150 | tm->tm_mon = bcd2bin(buf[M41T93_REG_MON]) - 1; | |
151 | tm->tm_wday = bcd2bin(buf[M41T93_REG_WDAY] & 0x0f) - 1; | |
152 | ||
153 | century_after_1900 = (buf[M41T93_REG_CENT_HOUR] >> 6) + 1; | |
154 | tm->tm_year = bcd2bin(buf[M41T93_REG_YEAR]) + century_after_1900 * 100; | |
155 | ||
156 | dev_dbg(dev, "%s secs=%d, mins=%d, " | |
157 | "hours=%d, mday=%d, mon=%d, year=%d, wday=%d\n", | |
158 | "read", tm->tm_sec, tm->tm_min, | |
159 | tm->tm_hour, tm->tm_mday, | |
160 | tm->tm_mon, tm->tm_year, tm->tm_wday); | |
161 | ||
162 | return ret < 0 ? ret : rtc_valid_tm(tm); | |
163 | } | |
164 | ||
165 | ||
166 | static const struct rtc_class_ops m41t93_rtc_ops = { | |
167 | .read_time = m41t93_get_time, | |
168 | .set_time = m41t93_set_time, | |
169 | }; | |
170 | ||
171 | static struct spi_driver m41t93_driver; | |
172 | ||
5a167f45 | 173 | static int m41t93_probe(struct spi_device *spi) |
74d34d4b VN |
174 | { |
175 | struct rtc_device *rtc; | |
176 | int res; | |
177 | ||
178 | spi->bits_per_word = 8; | |
179 | spi_setup(spi); | |
180 | ||
181 | res = spi_w8r8(spi, M41T93_REG_WDAY); | |
182 | if (res < 0 || (res & 0xf8) != 0) { | |
183 | dev_err(&spi->dev, "not found 0x%x.\n", res); | |
184 | return -ENODEV; | |
185 | } | |
186 | ||
187 | rtc = rtc_device_register(m41t93_driver.driver.name, | |
188 | &spi->dev, &m41t93_rtc_ops, THIS_MODULE); | |
189 | if (IS_ERR(rtc)) | |
190 | return PTR_ERR(rtc); | |
191 | ||
192 | dev_set_drvdata(&spi->dev, rtc); | |
193 | ||
194 | return 0; | |
195 | } | |
196 | ||
197 | ||
5a167f45 | 198 | static int m41t93_remove(struct spi_device *spi) |
74d34d4b | 199 | { |
a80fd9db | 200 | struct rtc_device *rtc = spi_get_drvdata(spi); |
74d34d4b VN |
201 | |
202 | if (rtc) | |
203 | rtc_device_unregister(rtc); | |
204 | ||
205 | return 0; | |
206 | } | |
207 | ||
208 | static struct spi_driver m41t93_driver = { | |
209 | .driver = { | |
210 | .name = "rtc-m41t93", | |
74d34d4b VN |
211 | .owner = THIS_MODULE, |
212 | }, | |
213 | .probe = m41t93_probe, | |
5a167f45 | 214 | .remove = m41t93_remove, |
74d34d4b VN |
215 | }; |
216 | ||
109e9418 | 217 | module_spi_driver(m41t93_driver); |
74d34d4b VN |
218 | |
219 | MODULE_AUTHOR("Nikolaus Voss <n.voss@weinmann.de>"); | |
220 | MODULE_DESCRIPTION("Driver for ST M41T93 SPI RTC"); | |
221 | MODULE_LICENSE("GPL"); | |
222 | MODULE_ALIAS("spi:rtc-m41t93"); |