Voss, Nikolaus | 74d34d4 | 2011-05-26 16:25:07 -0700 | [diff] [blame] | 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); |
Nikolaus Voss | bcffb10 | 2012-05-29 15:07:39 -0700 | [diff] [blame] | 51 | int tmp; |
Voss, Nikolaus | 74d34d4 | 2011-05-26 16:25:07 -0700 | [diff] [blame] | 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 | |
Nikolaus Voss | bcffb10 | 2012-05-29 15:07:39 -0700 | [diff] [blame] | 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 | |
Voss, Nikolaus | 74d34d4 | 2011-05-26 16:25:07 -0700 | [diff] [blame] | 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. |
Nikolaus Voss | bcffb10 | 2012-05-29 15:07:39 -0700 | [diff] [blame] | 117 | 2. oscillator fail bit (OF) is set: time is invalid. |
Voss, Nikolaus | 74d34d4 | 2011-05-26 16:25:07 -0700 | [diff] [blame] | 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; |
Nikolaus Voss | bcffb10 | 2012-05-29 15:07:39 -0700 | [diff] [blame] | 135 | dev_warn(&spi->dev, "OF bit is set, write time to restart.\n"); |
Voss, Nikolaus | 74d34d4 | 2011-05-26 16:25:07 -0700 | [diff] [blame] | 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 | |
Greg Kroah-Hartman | 5a167f4 | 2012-12-21 13:09:38 -0800 | [diff] [blame] | 173 | static int m41t93_probe(struct spi_device *spi) |
Voss, Nikolaus | 74d34d4 | 2011-05-26 16:25:07 -0700 | [diff] [blame] | 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 | |
Jingoo Han | 0166fcd | 2013-04-29 16:19:40 -0700 | [diff] [blame] | 187 | rtc = devm_rtc_device_register(&spi->dev, m41t93_driver.driver.name, |
| 188 | &m41t93_rtc_ops, THIS_MODULE); |
Voss, Nikolaus | 74d34d4 | 2011-05-26 16:25:07 -0700 | [diff] [blame] | 189 | if (IS_ERR(rtc)) |
| 190 | return PTR_ERR(rtc); |
| 191 | |
Jingoo Han | b6c4e71a | 2013-04-29 16:20:21 -0700 | [diff] [blame] | 192 | spi_set_drvdata(spi, rtc); |
Voss, Nikolaus | 74d34d4 | 2011-05-26 16:25:07 -0700 | [diff] [blame] | 193 | |
| 194 | return 0; |
| 195 | } |
| 196 | |
Voss, Nikolaus | 74d34d4 | 2011-05-26 16:25:07 -0700 | [diff] [blame] | 197 | static struct spi_driver m41t93_driver = { |
| 198 | .driver = { |
| 199 | .name = "rtc-m41t93", |
Voss, Nikolaus | 74d34d4 | 2011-05-26 16:25:07 -0700 | [diff] [blame] | 200 | }, |
| 201 | .probe = m41t93_probe, |
Voss, Nikolaus | 74d34d4 | 2011-05-26 16:25:07 -0700 | [diff] [blame] | 202 | }; |
| 203 | |
Axel Lin | 109e941 | 2012-03-23 15:02:30 -0700 | [diff] [blame] | 204 | module_spi_driver(m41t93_driver); |
Voss, Nikolaus | 74d34d4 | 2011-05-26 16:25:07 -0700 | [diff] [blame] | 205 | |
| 206 | MODULE_AUTHOR("Nikolaus Voss <n.voss@weinmann.de>"); |
| 207 | MODULE_DESCRIPTION("Driver for ST M41T93 SPI RTC"); |
| 208 | MODULE_LICENSE("GPL"); |
| 209 | MODULE_ALIAS("spi:rtc-m41t93"); |