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1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 | /* * * Driver for ST M41T93 SPI RTC * * (c) 2010 Nikolaus Voss, Weinmann Medical GmbH * * This program is free software; you can redistribute it and/or modify * it under the terms of the GNU General Public License version 2 as * published by the Free Software Foundation. */ #include <linux/bcd.h> #include <linux/kernel.h> #include <linux/module.h> #include <linux/platform_device.h> #include <linux/rtc.h> #include <linux/spi/spi.h> #define M41T93_REG_SSEC 0 #define M41T93_REG_ST_SEC 1 #define M41T93_REG_MIN 2 #define M41T93_REG_CENT_HOUR 3 #define M41T93_REG_WDAY 4 #define M41T93_REG_DAY 5 #define M41T93_REG_MON 6 #define M41T93_REG_YEAR 7 #define M41T93_REG_ALM_HOUR_HT 0xc #define M41T93_REG_FLAGS 0xf #define M41T93_FLAG_ST (1 << 7) #define M41T93_FLAG_OF (1 << 2) #define M41T93_FLAG_BL (1 << 4) #define M41T93_FLAG_HT (1 << 6) static inline int m41t93_set_reg(struct spi_device *spi, u8 addr, u8 data) { u8 buf[2]; /* MSB must be '1' to write */ buf[0] = addr | 0x80; buf[1] = data; return spi_write(spi, buf, sizeof(buf)); } static int m41t93_set_time(struct device *dev, struct rtc_time *tm) { struct spi_device *spi = to_spi_device(dev); int tmp; u8 buf[9] = {0x80}; /* write cmd + 8 data bytes */ u8 * const data = &buf[1]; /* ptr to first data byte */ dev_dbg(dev, "%s secs=%d, mins=%d, " "hours=%d, mday=%d, mon=%d, year=%d, wday=%d\n", "write", tm->tm_sec, tm->tm_min, tm->tm_hour, tm->tm_mday, tm->tm_mon, tm->tm_year, tm->tm_wday); if (tm->tm_year < 100) { dev_warn(&spi->dev, "unsupported date (before 2000-01-01).\n"); return -EINVAL; } tmp = spi_w8r8(spi, M41T93_REG_FLAGS); if (tmp < 0) return tmp; if (tmp & M41T93_FLAG_OF) { dev_warn(&spi->dev, "OF bit is set, resetting.\n"); m41t93_set_reg(spi, M41T93_REG_FLAGS, tmp & ~M41T93_FLAG_OF); tmp = spi_w8r8(spi, M41T93_REG_FLAGS); if (tmp < 0) { return tmp; } else if (tmp & M41T93_FLAG_OF) { /* OF cannot be immediately reset: oscillator has to be * restarted. */ u8 reset_osc = buf[M41T93_REG_ST_SEC] | M41T93_FLAG_ST; dev_warn(&spi->dev, "OF bit is still set, kickstarting clock.\n"); m41t93_set_reg(spi, M41T93_REG_ST_SEC, reset_osc); reset_osc &= ~M41T93_FLAG_ST; m41t93_set_reg(spi, M41T93_REG_ST_SEC, reset_osc); } } data[M41T93_REG_SSEC] = 0; data[M41T93_REG_ST_SEC] = bin2bcd(tm->tm_sec); data[M41T93_REG_MIN] = bin2bcd(tm->tm_min); data[M41T93_REG_CENT_HOUR] = bin2bcd(tm->tm_hour) | ((tm->tm_year/100-1) << 6); data[M41T93_REG_DAY] = bin2bcd(tm->tm_mday); data[M41T93_REG_WDAY] = bin2bcd(tm->tm_wday + 1); data[M41T93_REG_MON] = bin2bcd(tm->tm_mon + 1); data[M41T93_REG_YEAR] = bin2bcd(tm->tm_year % 100); return spi_write(spi, buf, sizeof(buf)); } static int m41t93_get_time(struct device *dev, struct rtc_time *tm) { struct spi_device *spi = to_spi_device(dev); const u8 start_addr = 0; u8 buf[8]; int century_after_1900; int tmp; int ret = 0; /* Check status of clock. Two states must be considered: 1. halt bit (HT) is set: the clock is running but update of readout registers has been disabled due to power failure. This is normal case after poweron. Time is valid after resetting HT bit. 2. oscillator fail bit (OF) is set: time is invalid. */ tmp = spi_w8r8(spi, M41T93_REG_ALM_HOUR_HT); if (tmp < 0) return tmp; if (tmp & M41T93_FLAG_HT) { dev_dbg(&spi->dev, "HT bit is set, reenable clock update.\n"); m41t93_set_reg(spi, M41T93_REG_ALM_HOUR_HT, tmp & ~M41T93_FLAG_HT); } tmp = spi_w8r8(spi, M41T93_REG_FLAGS); if (tmp < 0) return tmp; if (tmp & M41T93_FLAG_OF) { ret = -EINVAL; dev_warn(&spi->dev, "OF bit is set, write time to restart.\n"); } if (tmp & M41T93_FLAG_BL) dev_warn(&spi->dev, "BL bit is set, replace battery.\n"); /* read actual time/date */ tmp = spi_write_then_read(spi, &start_addr, 1, buf, sizeof(buf)); if (tmp < 0) return tmp; tm->tm_sec = bcd2bin(buf[M41T93_REG_ST_SEC]); tm->tm_min = bcd2bin(buf[M41T93_REG_MIN]); tm->tm_hour = bcd2bin(buf[M41T93_REG_CENT_HOUR] & 0x3f); tm->tm_mday = bcd2bin(buf[M41T93_REG_DAY]); tm->tm_mon = bcd2bin(buf[M41T93_REG_MON]) - 1; tm->tm_wday = bcd2bin(buf[M41T93_REG_WDAY] & 0x0f) - 1; century_after_1900 = (buf[M41T93_REG_CENT_HOUR] >> 6) + 1; tm->tm_year = bcd2bin(buf[M41T93_REG_YEAR]) + century_after_1900 * 100; dev_dbg(dev, "%s secs=%d, mins=%d, " "hours=%d, mday=%d, mon=%d, year=%d, wday=%d\n", "read", tm->tm_sec, tm->tm_min, tm->tm_hour, tm->tm_mday, tm->tm_mon, tm->tm_year, tm->tm_wday); return ret < 0 ? ret : rtc_valid_tm(tm); } static const struct rtc_class_ops m41t93_rtc_ops = { .read_time = m41t93_get_time, .set_time = m41t93_set_time, }; static struct spi_driver m41t93_driver; static int m41t93_probe(struct spi_device *spi) { struct rtc_device *rtc; int res; spi->bits_per_word = 8; spi_setup(spi); res = spi_w8r8(spi, M41T93_REG_WDAY); if (res < 0 || (res & 0xf8) != 0) { dev_err(&spi->dev, "not found 0x%x.\n", res); return -ENODEV; } rtc = devm_rtc_device_register(&spi->dev, m41t93_driver.driver.name, &m41t93_rtc_ops, THIS_MODULE); if (IS_ERR(rtc)) return PTR_ERR(rtc); spi_set_drvdata(spi, rtc); return 0; } static struct spi_driver m41t93_driver = { .driver = { .name = "rtc-m41t93", }, .probe = m41t93_probe, }; module_spi_driver(m41t93_driver); MODULE_AUTHOR("Nikolaus Voss <n.voss@weinmann.de>"); MODULE_DESCRIPTION("Driver for ST M41T93 SPI RTC"); MODULE_LICENSE("GPL"); MODULE_ALIAS("spi:rtc-m41t93"); |