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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 | /* rtc-max6916.c * * Driver for MAXIM max6916 Low Current, SPI Compatible * Real Time Clock * * Author : Venkat Prashanth B U <venkat.prashanth2498@gmail.com> * * 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/init.h> #include <linux/module.h> #include <linux/device.h> #include <linux/platform_device.h> #include <linux/rtc.h> #include <linux/spi/spi.h> #include <linux/bcd.h> /* Registers in max6916 rtc */ #define MAX6916_SECONDS_REG 0x01 #define MAX6916_MINUTES_REG 0x02 #define MAX6916_HOURS_REG 0x03 #define MAX6916_DATE_REG 0x04 #define MAX6916_MONTH_REG 0x05 #define MAX6916_DAY_REG 0x06 #define MAX6916_YEAR_REG 0x07 #define MAX6916_CONTROL_REG 0x08 #define MAX6916_STATUS_REG 0x0C #define MAX6916_CLOCK_BURST 0x3F static int max6916_read_reg(struct device *dev, unsigned char address, unsigned char *data) { struct spi_device *spi = to_spi_device(dev); *data = address | 0x80; return spi_write_then_read(spi, data, 1, data, 1); } static int max6916_write_reg(struct device *dev, unsigned char address, unsigned char data) { struct spi_device *spi = to_spi_device(dev); unsigned char buf[2]; buf[0] = address & 0x7F; buf[1] = data; return spi_write_then_read(spi, buf, 2, NULL, 0); } static int max6916_read_time(struct device *dev, struct rtc_time *dt) { struct spi_device *spi = to_spi_device(dev); int err; unsigned char buf[8]; buf[0] = MAX6916_CLOCK_BURST | 0x80; err = spi_write_then_read(spi, buf, 1, buf, 8); if (err) return err; dt->tm_sec = bcd2bin(buf[0]); dt->tm_min = bcd2bin(buf[1]); dt->tm_hour = bcd2bin(buf[2] & 0x3F); dt->tm_mday = bcd2bin(buf[3]); dt->tm_mon = bcd2bin(buf[4]) - 1; dt->tm_wday = bcd2bin(buf[5]) - 1; dt->tm_year = bcd2bin(buf[6]) + 100; return rtc_valid_tm(dt); } static int max6916_set_time(struct device *dev, struct rtc_time *dt) { struct spi_device *spi = to_spi_device(dev); unsigned char buf[9]; if (dt->tm_year < 100 || dt->tm_year > 199) { dev_err(&spi->dev, "Year must be between 2000 and 2099. It's %d.\n", dt->tm_year + 1900); return -EINVAL; } buf[0] = MAX6916_CLOCK_BURST & 0x7F; buf[1] = bin2bcd(dt->tm_sec); buf[2] = bin2bcd(dt->tm_min); buf[3] = (bin2bcd(dt->tm_hour) & 0X3F); buf[4] = bin2bcd(dt->tm_mday); buf[5] = bin2bcd(dt->tm_mon + 1); buf[6] = bin2bcd(dt->tm_wday + 1); buf[7] = bin2bcd(dt->tm_year % 100); buf[8] = bin2bcd(0x00); /* write the rtc settings */ return spi_write_then_read(spi, buf, 9, NULL, 0); } static const struct rtc_class_ops max6916_rtc_ops = { .read_time = max6916_read_time, .set_time = max6916_set_time, }; static int max6916_probe(struct spi_device *spi) { struct rtc_device *rtc; unsigned char data; int res; /* spi setup with max6916 in mode 3 and bits per word as 8 */ spi->mode = SPI_MODE_3; spi->bits_per_word = 8; spi_setup(spi); /* RTC Settings */ res = max6916_read_reg(&spi->dev, MAX6916_SECONDS_REG, &data); if (res) return res; /* Disable the write protect of rtc */ max6916_read_reg(&spi->dev, MAX6916_CONTROL_REG, &data); data = data & ~(1 << 7); max6916_write_reg(&spi->dev, MAX6916_CONTROL_REG, data); /*Enable oscillator,disable oscillator stop flag, glitch filter*/ max6916_read_reg(&spi->dev, MAX6916_STATUS_REG, &data); data = data & 0x1B; max6916_write_reg(&spi->dev, MAX6916_STATUS_REG, data); /* display the settings */ max6916_read_reg(&spi->dev, MAX6916_CONTROL_REG, &data); dev_info(&spi->dev, "MAX6916 RTC CTRL Reg = 0x%02x\n", data); max6916_read_reg(&spi->dev, MAX6916_STATUS_REG, &data); dev_info(&spi->dev, "MAX6916 RTC Status Reg = 0x%02x\n", data); rtc = devm_rtc_device_register(&spi->dev, "max6916", &max6916_rtc_ops, THIS_MODULE); if (IS_ERR(rtc)) return PTR_ERR(rtc); spi_set_drvdata(spi, rtc); return 0; } static struct spi_driver max6916_driver = { .driver = { .name = "max6916", }, .probe = max6916_probe, }; module_spi_driver(max6916_driver); MODULE_DESCRIPTION("MAX6916 SPI RTC DRIVER"); MODULE_AUTHOR("Venkat Prashanth B U <venkat.prashanth2498@gmail.com>"); MODULE_LICENSE("GPL v2"); |