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1// SPDX-License-Identifier: GPL-2.0-only2/* drivers/rtc/rtc-max6902.c3 *4 * Copyright (C) 2006 8D Technologies inc.5 * Copyright (C) 2004 Compulab Ltd.6 *7 * Driver for MAX6902 spi RTC8 */9 10#include <linux/module.h>11#include <linux/kernel.h>12#include <linux/platform_device.h>13#include <linux/init.h>14#include <linux/rtc.h>15#include <linux/spi/spi.h>16#include <linux/bcd.h>17 18#define MAX6902_REG_SECONDS 0x0119#define MAX6902_REG_MINUTES 0x0320#define MAX6902_REG_HOURS 0x0521#define MAX6902_REG_DATE 0x0722#define MAX6902_REG_MONTH 0x0923#define MAX6902_REG_DAY 0x0B24#define MAX6902_REG_YEAR 0x0D25#define MAX6902_REG_CONTROL 0x0F26#define MAX6902_REG_CENTURY 0x1327 28static int max6902_set_reg(struct device *dev, unsigned char address,29 unsigned char data)30{31 struct spi_device *spi = to_spi_device(dev);32 unsigned char buf[2];33 34 /* MSB must be '0' to write */35 buf[0] = address & 0x7f;36 buf[1] = data;37 38 return spi_write_then_read(spi, buf, 2, NULL, 0);39}40 41static int max6902_get_reg(struct device *dev, unsigned char address,42 unsigned char *data)43{44 struct spi_device *spi = to_spi_device(dev);45 46 /* Set MSB to indicate read */47 *data = address | 0x80;48 49 return spi_write_then_read(spi, data, 1, data, 1);50}51 52static int max6902_read_time(struct device *dev, struct rtc_time *dt)53{54 int err, century;55 struct spi_device *spi = to_spi_device(dev);56 unsigned char buf[8];57 58 buf[0] = 0xbf; /* Burst read */59 60 err = spi_write_then_read(spi, buf, 1, buf, 8);61 if (err != 0)62 return err;63 64 /* The chip sends data in this order:65 * Seconds, Minutes, Hours, Date, Month, Day, Year */66 dt->tm_sec = bcd2bin(buf[0]);67 dt->tm_min = bcd2bin(buf[1]);68 dt->tm_hour = bcd2bin(buf[2]);69 dt->tm_mday = bcd2bin(buf[3]);70 dt->tm_mon = bcd2bin(buf[4]) - 1;71 dt->tm_wday = bcd2bin(buf[5]);72 dt->tm_year = bcd2bin(buf[6]);73 74 /* Read century */75 err = max6902_get_reg(dev, MAX6902_REG_CENTURY, &buf[0]);76 if (err != 0)77 return err;78 79 century = bcd2bin(buf[0]) * 100;80 81 dt->tm_year += century;82 dt->tm_year -= 1900;83 84 return 0;85}86 87static int max6902_set_time(struct device *dev, struct rtc_time *dt)88{89 dt->tm_year = dt->tm_year + 1900;90 91 /* Remove write protection */92 max6902_set_reg(dev, MAX6902_REG_CONTROL, 0);93 94 max6902_set_reg(dev, MAX6902_REG_SECONDS, bin2bcd(dt->tm_sec));95 max6902_set_reg(dev, MAX6902_REG_MINUTES, bin2bcd(dt->tm_min));96 max6902_set_reg(dev, MAX6902_REG_HOURS, bin2bcd(dt->tm_hour));97 98 max6902_set_reg(dev, MAX6902_REG_DATE, bin2bcd(dt->tm_mday));99 max6902_set_reg(dev, MAX6902_REG_MONTH, bin2bcd(dt->tm_mon + 1));100 max6902_set_reg(dev, MAX6902_REG_DAY, bin2bcd(dt->tm_wday));101 max6902_set_reg(dev, MAX6902_REG_YEAR, bin2bcd(dt->tm_year % 100));102 max6902_set_reg(dev, MAX6902_REG_CENTURY, bin2bcd(dt->tm_year / 100));103 104 /* Compulab used a delay here. However, the datasheet105 * does not mention a delay being required anywhere... */106 /* delay(2000); */107 108 /* Write protect */109 max6902_set_reg(dev, MAX6902_REG_CONTROL, 0x80);110 111 return 0;112}113 114static const struct rtc_class_ops max6902_rtc_ops = {115 .read_time = max6902_read_time,116 .set_time = max6902_set_time,117};118 119static int max6902_probe(struct spi_device *spi)120{121 struct rtc_device *rtc;122 unsigned char tmp;123 int res;124 125 spi->mode = SPI_MODE_3;126 spi->bits_per_word = 8;127 spi_setup(spi);128 129 res = max6902_get_reg(&spi->dev, MAX6902_REG_SECONDS, &tmp);130 if (res != 0)131 return res;132 133 rtc = devm_rtc_device_register(&spi->dev, "max6902",134 &max6902_rtc_ops, THIS_MODULE);135 if (IS_ERR(rtc))136 return PTR_ERR(rtc);137 138 spi_set_drvdata(spi, rtc);139 return 0;140}141 142static struct spi_driver max6902_driver = {143 .driver = {144 .name = "rtc-max6902",145 },146 .probe = max6902_probe,147};148 149module_spi_driver(max6902_driver);150 151MODULE_DESCRIPTION("max6902 spi RTC driver");152MODULE_AUTHOR("Raphael Assenat");153MODULE_LICENSE("GPL");154MODULE_ALIAS("spi:rtc-max6902");155