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