/* drivers/char/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/config.h>
#include <linux/module.h>
#include <linux/version.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)
status = message.status;
else
return status;
*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 == 0)
status = message.status;
else
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",__FUNCTION__);
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",__FUNCTION__);
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 = "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");
