/* drivers/rtc/rtc-max6902.c * * Copyright (C) 2006 8D Technologies inc. * Copyright (C) 2004 Compulab Ltd. * * 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. * * Driver for MAX6902 spi RTC * * Changelog: * * 24-May-2006: Raphael Assenat <raph@8d.com> * - Major rework * Converted to rtc_device and uses the SPI layer. * * ??-???-2005: Someone at Compulab * - Initial driver creation. */ #include <linux/module.h> #include <linux/kernel.h> #include <linux/platform_device.h> #include <linux/init.h> #include <linux/rtc.h> #include <linux/spi/spi.h> #include <linux/bcd.h> #include <linux/delay.h> #define MAX6902_REG_SECONDS 0x01 #define MAX6902_REG_MINUTES 0x03 #define MAX6902_REG_HOURS 0x05 #define MAX6902_REG_DATE 0x07 #define MAX6902_REG_MONTH 0x09 #define MAX6902_REG_DAY 0x0B #define MAX6902_REG_YEAR 0x0D #define MAX6902_REG_CONTROL 0x0F #define MAX6902_REG_CENTURY 0x13 #undef MAX6902_DEBUG struct max6902 { struct rtc_device *rtc; u8 buf[9]; /* Burst read cmd + 8 registers */ u8 tx_buf[2]; u8 rx_buf[2]; }; static void max6902_set_reg(struct device *dev, unsigned char address, unsigned char data) { struct spi_device *spi = to_spi_device(dev); unsigned char buf[2]; /* MSB must be '0' to write */ buf[0] = address & 0x7f; buf[1] = data; spi_write(spi, buf, 2); } static int max6902_get_reg(struct device *dev, unsigned char address, unsigned char *data) { struct spi_device *spi = to_spi_device(dev); struct max6902 *chip = dev_get_drvdata(dev); struct spi_message message; struct spi_transfer xfer; int status; if (!data) return -EINVAL; /* Build our spi message */ spi_message_init(&message); memset(&xfer, 0, sizeof(xfer)); xfer.len = 2; /* Can tx_buf and rx_buf be equal? The doc in spi.h is not sure... */ xfer.tx_buf = chip->tx_buf; xfer.rx_buf = chip->rx_buf; /* Set MSB to indicate read */ chip->tx_buf[0] = address | 0x80; spi_message_add_tail(&xfer, &message); /* do the i/o */ status = spi_sync(spi, &message); if (status == 0) *data = chip->rx_buf[1]; return status; } static int max6902_get_datetime(struct device *dev, struct rtc_time *dt) { unsigned char tmp; int century; int err; struct spi_device *spi = to_spi_device(dev); struct max6902 *chip = dev_get_drvdata(dev); struct spi_message message; struct spi_transfer xfer; int status; err = max6902_get_reg(dev, MAX6902_REG_CENTURY, &tmp); if (err) return err; /* build the message */ spi_message_init(&message); memset(&xfer, 0, sizeof(xfer)); xfer.len = 1 + 7; /* Burst read command + 7 registers */ xfer.tx_buf = chip->buf; xfer.rx_buf = chip->buf; chip->buf[0] = 0xbf; /* Burst read */ spi_message_add_tail(&xfer, &message); /* do the i/o */ status = spi_sync(spi, &message); if (status) return status; /* The chip sends data in this order: * Seconds, Minutes, Hours, Date, Month, Day, Year */ dt->tm_sec = BCD2BIN(chip->buf[1]); dt->tm_min = BCD2BIN(chip->buf[2]); dt->tm_hour = BCD2BIN(chip->buf[3]); dt->tm_mday = BCD2BIN(chip->buf[4]); dt->tm_mon = BCD2BIN(chip->buf[5]) - 1; dt->tm_wday = BCD2BIN(chip->buf[6]); dt->tm_year = BCD2BIN(chip->buf[7]); century = BCD2BIN(tmp) * 100; dt->tm_year += century; dt->tm_year -= 1900; #ifdef MAX6902_DEBUG printk("\n%s : Read RTC values\n",__func__); printk("tm_hour: %i\n",dt->tm_hour); printk("tm_min : %i\n",dt->tm_min); printk("tm_sec : %i\n",dt->tm_sec); printk("tm_year: %i\n",dt->tm_year); printk("tm_mon : %i\n",dt->tm_mon); printk("tm_mday: %i\n",dt->tm_mday); printk("tm_wday: %i\n",dt->tm_wday); #endif return 0; } static int max6902_set_datetime(struct device *dev, struct rtc_time *dt) { dt->tm_year = dt->tm_year+1900; #ifdef MAX6902_DEBUG printk("\n%s : Setting RTC values\n",__func__); printk("tm_sec : %i\n",dt->tm_sec); printk("tm_min : %i\n",dt->tm_min); printk("tm_hour: %i\n",dt->tm_hour); printk("tm_mday: %i\n",dt->tm_mday); printk("tm_wday: %i\n",dt->tm_wday); printk("tm_year: %i\n",dt->tm_year); #endif /* Remove write protection */ max6902_set_reg(dev, 0xF, 0); max6902_set_reg(dev, 0x01, BIN2BCD(dt->tm_sec)); max6902_set_reg(dev, 0x03, BIN2BCD(dt->tm_min)); max6902_set_reg(dev, 0x05, BIN2BCD(dt->tm_hour)); max6902_set_reg(dev, 0x07, BIN2BCD(dt->tm_mday)); max6902_set_reg(dev, 0x09, BIN2BCD(dt->tm_mon+1)); max6902_set_reg(dev, 0x0B, BIN2BCD(dt->tm_wday)); max6902_set_reg(dev, 0x0D, BIN2BCD(dt->tm_year%100)); max6902_set_reg(dev, 0x13, BIN2BCD(dt->tm_year/100)); /* Compulab used a delay here. However, the datasheet * does not mention a delay being required anywhere... */ /* delay(2000); */ /* Write protect */ max6902_set_reg(dev, 0xF, 0x80); return 0; } static int max6902_read_time(struct device *dev, struct rtc_time *tm) { return max6902_get_datetime(dev, tm); } static int max6902_set_time(struct device *dev, struct rtc_time *tm) { return max6902_set_datetime(dev, tm); } static const struct rtc_class_ops max6902_rtc_ops = { .read_time = max6902_read_time, .set_time = max6902_set_time, }; static int __devinit max6902_probe(struct spi_device *spi) { struct rtc_device *rtc; unsigned char tmp; struct max6902 *chip; int res; rtc = rtc_device_register("max6902", &spi->dev, &max6902_rtc_ops, THIS_MODULE); if (IS_ERR(rtc)) return PTR_ERR(rtc); spi->mode = SPI_MODE_3; spi->bits_per_word = 8; spi_setup(spi); chip = kzalloc(sizeof *chip, GFP_KERNEL); if (!chip) { rtc_device_unregister(rtc); return -ENOMEM; } chip->rtc = rtc; dev_set_drvdata(&spi->dev, chip); res = max6902_get_reg(&spi->dev, MAX6902_REG_SECONDS, &tmp); if (res) { rtc_device_unregister(rtc); return res; } return 0; } static int __devexit max6902_remove(struct spi_device *spi) { struct max6902 *chip = platform_get_drvdata(spi); struct rtc_device *rtc = chip->rtc; if (rtc) rtc_device_unregister(rtc); kfree(chip); return 0; } static struct spi_driver max6902_driver = { .driver = { .name = "rtc-max6902", .bus = &spi_bus_type, .owner = THIS_MODULE, }, .probe = max6902_probe, .remove = __devexit_p(max6902_remove), }; static __init int max6902_init(void) { printk("max6902 spi driver\n"); return spi_register_driver(&max6902_driver); } module_init(max6902_init); static __exit void max6902_exit(void) { spi_unregister_driver(&max6902_driver); } module_exit(max6902_exit); MODULE_DESCRIPTION ("max6902 spi RTC driver"); MODULE_AUTHOR ("Raphael Assenat"); MODULE_LICENSE ("GPL");