arch/cris/arch-v10/drivers/ds1302.c - kernel/windcharger - Git at Google

 /*!***************************************************************************
 *!
 *! FILE NAME  : ds1302.c
 *!
 *! DESCRIPTION: Implements an interface for the DS1302 RTC through Etrax I/O
 *!
 *! Functions exported: ds1302_readreg, ds1302_writereg, ds1302_init
 *!
 *! ---------------------------------------------------------------------------
 *!
 *! (C) Copyright 1999-2007 Axis Communications AB, LUND, SWEDEN
 *!
 *!***************************************************************************/


 #include <linux/fs.h>
 #include <linux/init.h>
 #include <linux/mm.h>
 #include <linux/module.h>
 #include <linux/miscdevice.h>
 #include <linux/delay.h>
 #include <linux/bcd.h>
 #include <linux/capability.h>

 #include <asm/uaccess.h>
 #include <asm/system.h>
 #include <arch/svinto.h>
 #include <asm/io.h>
 #include <asm/rtc.h>
 #include <arch/io_interface_mux.h>

 #include "i2c.h"

 #define RTC_MAJOR_NR 121 /* local major, change later */

 static const char ds1302_name[] = "ds1302";

 /* The DS1302 might be connected to different bits on different products.
  * It has three signals - SDA, SCL and RST. RST and SCL are always outputs,
  * but SDA can have a selected direction.
  * For now, only PORT_PB is hardcoded.
  */

 /* The RST bit may be on either the Generic Port or Port PB. */
 #ifdef CONFIG_ETRAX_DS1302_RST_ON_GENERIC_PORT
 #define TK_RST_OUT(x) REG_SHADOW_SET(R_PORT_G_DATA,  port_g_data_shadow,  CONFIG_ETRAX_DS1302_RSTBIT, x)
 #define TK_RST_DIR(x)
 #else
 #define TK_RST_OUT(x) REG_SHADOW_SET(R_PORT_PB_DATA, port_pb_data_shadow, CONFIG_ETRAX_DS1302_RSTBIT, x)
 #define TK_RST_DIR(x) REG_SHADOW_SET(R_PORT_PB_DIR,  port_pb_dir_shadow,  CONFIG_ETRAX_DS1302_RSTBIT, x)
 #endif


 #define TK_SDA_OUT(x) REG_SHADOW_SET(R_PORT_PB_DATA, port_pb_data_shadow, CONFIG_ETRAX_DS1302_SDABIT, x)
 #define TK_SCL_OUT(x) REG_SHADOW_SET(R_PORT_PB_DATA, port_pb_data_shadow, CONFIG_ETRAX_DS1302_SCLBIT, x)

 #define TK_SDA_IN()   ((*R_PORT_PB_READ >> CONFIG_ETRAX_DS1302_SDABIT) & 1)
 /* 1 is out, 0 is in */
 #define TK_SDA_DIR(x) REG_SHADOW_SET(R_PORT_PB_DIR,  port_pb_dir_shadow,  CONFIG_ETRAX_DS1302_SDABIT, x)
 #define TK_SCL_DIR(x) REG_SHADOW_SET(R_PORT_PB_DIR,  port_pb_dir_shadow,  CONFIG_ETRAX_DS1302_SCLBIT, x)


 /*
  * The reason for tempudelay and not udelay is that loops_per_usec
  * (used in udelay) is not set when functions here are called from time.c
  */

 static void tempudelay(int usecs)
 {
 	volatile int loops;

 	for(loops = usecs * 12; loops > 0; loops--)
 		/* nothing */;
 }


 /* Send 8 bits. */
 static void
 out_byte(unsigned char x)
 {
 	int i;
 	TK_SDA_DIR(1);
 	for (i = 8; i--;) {
 		/* The chip latches incoming bits on the rising edge of SCL. */
 		TK_SCL_OUT(0);
 		TK_SDA_OUT(x & 1);
 		tempudelay(1);
 		TK_SCL_OUT(1);
 		tempudelay(1);
 		x >>= 1;
 	}
 	TK_SDA_DIR(0);
 }

 static unsigned char
 in_byte(void)
 {
 	unsigned char x = 0;
 	int i;

 	/* Read byte. Bits come LSB first, on the falling edge of SCL.
 	 * Assume SDA is in input direction already.
 	 */
 	TK_SDA_DIR(0);

 	for (i = 8; i--;) {
 		TK_SCL_OUT(0);
 		tempudelay(1);
 		x >>= 1;
 		x |= (TK_SDA_IN() << 7);
 		TK_SCL_OUT(1);
 		tempudelay(1);
 	}

 	return x;
 }

 /* Prepares for a transaction by de-activating RST (active-low). */

 static void
 start(void)
 {
 	TK_SCL_OUT(0);
 	tempudelay(1);
 	TK_RST_OUT(0);
 	tempudelay(5);
 	TK_RST_OUT(1);
 }

 /* Ends a transaction by taking RST active again. */

 static void
 stop(void)
 {
 	tempudelay(2);
 	TK_RST_OUT(0);
 }

 /* Enable writing. */

 static void
 ds1302_wenable(void)
 {
 	start();
 	out_byte(0x8e); /* Write control register  */
 	out_byte(0x00); /* Disable write protect bit 7 = 0 */
 	stop();
 }

 /* Disable writing. */

 static void
 ds1302_wdisable(void)
 {
 	start();
 	out_byte(0x8e); /* Write control register  */
 	out_byte(0x80); /* Disable write protect bit 7 = 0 */
 	stop();
 }


 /* Read a byte from the selected register in the DS1302. */

 unsigned char
 ds1302_readreg(int reg)
 {
 	unsigned char x;

 	start();
 	out_byte(0x81 | (reg << 1)); /* read register */
 	x = in_byte();
 	stop();

 	return x;
 }

 /* Write a byte to the selected register. */

 void
 ds1302_writereg(int reg, unsigned char val)
 {
 #ifndef CONFIG_ETRAX_RTC_READONLY
 	int do_writereg = 1;
 #else
 	int do_writereg = 0;

 	if (reg == RTC_TRICKLECHARGER)
 		do_writereg = 1;
 #endif

 	if (do_writereg) {
 		ds1302_wenable();
 		start();
 		out_byte(0x80 | (reg << 1)); /* write register */
 		out_byte(val);
 		stop();
 		ds1302_wdisable();
 	}
 }

 void
 get_rtc_time(struct rtc_time *rtc_tm)
 {
 	unsigned long flags;

 	local_irq_save(flags);

 	rtc_tm->tm_sec = CMOS_READ(RTC_SECONDS);
 	rtc_tm->tm_min = CMOS_READ(RTC_MINUTES);
 	rtc_tm->tm_hour = CMOS_READ(RTC_HOURS);
 	rtc_tm->tm_mday = CMOS_READ(RTC_DAY_OF_MONTH);
 	rtc_tm->tm_mon = CMOS_READ(RTC_MONTH);
 	rtc_tm->tm_year = CMOS_READ(RTC_YEAR);

 	local_irq_restore(flags);

 	rtc_tm->tm_sec = bcd2bin(rtc_tm->tm_sec);
 	rtc_tm->tm_min = bcd2bin(rtc_tm->tm_min);
 	rtc_tm->tm_hour = bcd2bin(rtc_tm->tm_hour);
 	rtc_tm->tm_mday = bcd2bin(rtc_tm->tm_mday);
 	rtc_tm->tm_mon = bcd2bin(rtc_tm->tm_mon);
 	rtc_tm->tm_year = bcd2bin(rtc_tm->tm_year);

 	/*
 	 * Account for differences between how the RTC uses the values
 	 * and how they are defined in a struct rtc_time;
 	 */

 	if (rtc_tm->tm_year <= 69)
 		rtc_tm->tm_year += 100;

 	rtc_tm->tm_mon--;
 }

 static unsigned char days_in_mo[] =
     {0, 31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31};

 /* ioctl that supports RTC_RD_TIME and RTC_SET_TIME (read and set time/date). */

 static int
 rtc_ioctl(struct inode *inode, struct file *file, unsigned int cmd,
 	  unsigned long arg)
 {
 	unsigned long flags;

 	switch(cmd) {
 		case RTC_RD_TIME:	/* read the time/date from RTC	*/
 		{
 			struct rtc_time rtc_tm;

 			memset(&rtc_tm, 0, sizeof (struct rtc_time));
 			get_rtc_time(&rtc_tm);
 			if (copy_to_user((struct rtc_time*)arg, &rtc_tm, sizeof(struct rtc_time)))
 				return -EFAULT;
 			return 0;
 		}

 		case RTC_SET_TIME:	/* set the RTC */
 		{
 			struct rtc_time rtc_tm;
 			unsigned char mon, day, hrs, min, sec, leap_yr;
 			unsigned int yrs;

 			if (!capable(CAP_SYS_TIME))
 				return -EPERM;

 			if (copy_from_user(&rtc_tm, (struct rtc_time*)arg, sizeof(struct rtc_time)))
 				return -EFAULT;

 			yrs = rtc_tm.tm_year + 1900;
 			mon = rtc_tm.tm_mon + 1;   /* tm_mon starts at zero */
 			day = rtc_tm.tm_mday;
 			hrs = rtc_tm.tm_hour;
 			min = rtc_tm.tm_min;
 			sec = rtc_tm.tm_sec;


 			if ((yrs < 1970) || (yrs > 2069))
 				return -EINVAL;

 			leap_yr = ((!(yrs % 4) && (yrs % 100)) || !(yrs % 400));

 			if ((mon > 12) || (day == 0))
 				return -EINVAL;

 			if (day > (days_in_mo[mon] + ((mon == 2) && leap_yr)))
 				return -EINVAL;

 			if ((hrs >= 24) || (min >= 60) || (sec >= 60))
 				return -EINVAL;

 			if (yrs >= 2000)
 				yrs -= 2000;	/* RTC (0, 1, ... 69) */
 			else
 				yrs -= 1900;	/* RTC (70, 71, ... 99) */

 			sec = bin2bcd(sec);
 			min = bin2bcd(min);
 			hrs = bin2bcd(hrs);
 			day = bin2bcd(day);
 			mon = bin2bcd(mon);
 			yrs = bin2bcd(yrs);

 			local_irq_save(flags);
 			CMOS_WRITE(yrs, RTC_YEAR);
 			CMOS_WRITE(mon, RTC_MONTH);
 			CMOS_WRITE(day, RTC_DAY_OF_MONTH);
 			CMOS_WRITE(hrs, RTC_HOURS);
 			CMOS_WRITE(min, RTC_MINUTES);
 			CMOS_WRITE(sec, RTC_SECONDS);
 			local_irq_restore(flags);

 			/* Notice that at this point, the RTC is updated but
 			 * the kernel is still running with the old time.
 			 * You need to set that separately with settimeofday
 			 * or adjtimex.
 			 */
 			return 0;
 		}

 		case RTC_SET_CHARGE: /* set the RTC TRICKLE CHARGE register */
 		{
 			int tcs_val;

 			if (!capable(CAP_SYS_TIME))
 				return -EPERM;

 			if(copy_from_user(&tcs_val, (int*)arg, sizeof(int)))
 				return -EFAULT;

 			tcs_val = RTC_TCR_PATTERN | (tcs_val & 0x0F);
 			ds1302_writereg(RTC_TRICKLECHARGER, tcs_val);
 			return 0;
 		}
 		case RTC_VL_READ:
 		{
 			/* TODO:
 			 * Implement voltage low detection support
 			 */
 			printk(KERN_WARNING "DS1302: RTC Voltage Low detection"
 			       " is not supported\n");
 			return 0;
 		}
 		case RTC_VL_CLR:
 		{
 			/* TODO:
 			 * Nothing to do since Voltage Low detection is not supported
 			 */
 			return 0;
 		}
 		default:
 			return -ENOIOCTLCMD;
 	}
 }

 static void
 print_rtc_status(void)
 {
 	struct rtc_time tm;

 	get_rtc_time(&tm);

 	/*
 	 * There is no way to tell if the luser has the RTC set for local
 	 * time or for Universal Standard Time (GMT). Probably local though.
 	 */

 	printk(KERN_INFO "rtc_time\t: %02d:%02d:%02d\n",
 	       tm.tm_hour, tm.tm_min, tm.tm_sec);
 	printk(KERN_INFO "rtc_date\t: %04d-%02d-%02d\n",
 	       tm.tm_year + 1900, tm.tm_mon + 1, tm.tm_mday);
 }

 /* The various file operations we support. */

 static const struct file_operations rtc_fops = {
 	.owner =	THIS_MODULE,
 	.ioctl =	rtc_ioctl,
 };

 /* Probe for the chip by writing something to its RAM and try reading it back. */

 #define MAGIC_PATTERN 0x42

 static int __init
 ds1302_probe(void)
 {
 	int retval, res;

 	TK_RST_DIR(1);
 	TK_SCL_DIR(1);
 	TK_SDA_DIR(0);

 	/* Try to talk to timekeeper. */

 	ds1302_wenable();
 	start();
 	out_byte(0xc0); /* write RAM byte 0 */
 	out_byte(MAGIC_PATTERN); /* write something magic */
 	start();
 	out_byte(0xc1); /* read RAM byte 0 */

 	if((res = in_byte()) == MAGIC_PATTERN) {
 		stop();
 		ds1302_wdisable();
 		printk(KERN_INFO "%s: RTC found.\n", ds1302_name);
 		printk(KERN_INFO "%s: SDA, SCL, RST on PB%i, PB%i, %s%i\n",
 		       ds1302_name,
 		       CONFIG_ETRAX_DS1302_SDABIT,
 		       CONFIG_ETRAX_DS1302_SCLBIT,
 #ifdef CONFIG_ETRAX_DS1302_RST_ON_GENERIC_PORT
 		       "GENIO",
 #else
 		       "PB",
 #endif
 		       CONFIG_ETRAX_DS1302_RSTBIT);
 		       print_rtc_status();
 		retval = 1;
 	} else {
 		stop();
 		retval = 0;
 	}

 	return retval;
 }


 /* Just probe for the RTC and register the device to handle the ioctl needed. */

 int __init
 ds1302_init(void)
 {
 #ifdef CONFIG_ETRAX_I2C
 	i2c_init();
 #endif

 	if (!ds1302_probe()) {
 #ifdef CONFIG_ETRAX_DS1302_RST_ON_GENERIC_PORT
 #if CONFIG_ETRAX_DS1302_RSTBIT == 27
 		/*
 		 * The only way to set g27 to output is to enable ATA.
 		 *
 		 * Make sure that R_GEN_CONFIG is setup correct.
 		 */
 		/* Allocating the ATA interface will grab almost all
 		 * pins in I/O groups a, b, c and d.  A consequence of
 		 * allocating the ATA interface is that the fixed
 		 * interfaces shared RAM, parallel port 0, parallel
 		 * port 1, parallel port W, SCSI-8 port 0, SCSI-8 port
 		 * 1, SCSI-W, serial port 2, serial port 3,
 		 * synchronous serial port 3 and USB port 2 and almost
 		 * all GPIO pins on port g cannot be used.
 		 */
 		if (cris_request_io_interface(if_ata, "ds1302/ATA")) {
 			printk(KERN_WARNING "ds1302: Failed to get IO interface\n");
 			return -1;
 		}

 #elif CONFIG_ETRAX_DS1302_RSTBIT == 0
 		if (cris_io_interface_allocate_pins(if_gpio_grp_a,
 						    'g',
 						    CONFIG_ETRAX_DS1302_RSTBIT,
 						    CONFIG_ETRAX_DS1302_RSTBIT)) {
 			printk(KERN_WARNING "ds1302: Failed to get IO interface\n");
 			return -1;
 		}

 		/* Set the direction of this bit to out. */
 		genconfig_shadow = ((genconfig_shadow &
  				     ~IO_MASK(R_GEN_CONFIG, g0dir)) |
  				   (IO_STATE(R_GEN_CONFIG, g0dir, out)));
 		*R_GEN_CONFIG = genconfig_shadow;
 #endif
 		if (!ds1302_probe()) {
 			printk(KERN_WARNING "%s: RTC not found.\n", ds1302_name);
 			return -1;
 		}
 #else
 		printk(KERN_WARNING "%s: RTC not found.\n", ds1302_name);
 		return -1;
 #endif
   	}
 	/* Initialise trickle charger */
 	ds1302_writereg(RTC_TRICKLECHARGER,
 			RTC_TCR_PATTERN |(CONFIG_ETRAX_DS1302_TRICKLE_CHARGE & 0x0F));
         /* Start clock by resetting CLOCK_HALT */
 	ds1302_writereg(RTC_SECONDS, (ds1302_readreg(RTC_SECONDS) & 0x7F));
 	return 0;
 }

 static int __init ds1302_register(void)
 {
 	ds1302_init();
 	if (register_chrdev(RTC_MAJOR_NR, ds1302_name, &rtc_fops)) {
 		printk(KERN_INFO "%s: unable to get major %d for rtc\n",
 		       ds1302_name, RTC_MAJOR_NR);
 		return -1;
 	}
         return 0;

 }

 module_init(ds1302_register);
	/!**************************************************************************
	*!
	*! FILE NAME : ds1302.c
	*!
	*! DESCRIPTION: Implements an interface for the DS1302 RTC through Etrax I/O
	*!
	*! Functions exported: ds1302_readreg, ds1302_writereg, ds1302_init
	*!
	*! ---------------------------------------------------------------------------
	*!
	*! (C) Copyright 1999-2007 Axis Communications AB, LUND, SWEDEN
	*!
	!**************************************************************************/


	#include <linux/fs.h>
	#include <linux/init.h>
	#include <linux/mm.h>
	#include <linux/module.h>
	#include <linux/miscdevice.h>
	#include <linux/delay.h>
	#include <linux/bcd.h>
	#include <linux/capability.h>

	#include <asm/uaccess.h>
	#include <asm/system.h>
	#include <arch/svinto.h>
	#include <asm/io.h>
	#include <asm/rtc.h>
	#include <arch/io_interface_mux.h>

	#include "i2c.h"

	#define RTC_MAJOR_NR 121 /* local major, change later */

	static const char ds1302_name[] = "ds1302";

	/* The DS1302 might be connected to different bits on different products.
	* It has three signals - SDA, SCL and RST. RST and SCL are always outputs,
	* but SDA can have a selected direction.
	* For now, only PORT_PB is hardcoded.
	*/

	/* The RST bit may be on either the Generic Port or Port PB. */
	#ifdef CONFIG_ETRAX_DS1302_RST_ON_GENERIC_PORT
	#define TK_RST_OUT(x) REG_SHADOW_SET(R_PORT_G_DATA, port_g_data_shadow, CONFIG_ETRAX_DS1302_RSTBIT, x)
	#define TK_RST_DIR(x)
	#else
	#define TK_RST_OUT(x) REG_SHADOW_SET(R_PORT_PB_DATA, port_pb_data_shadow, CONFIG_ETRAX_DS1302_RSTBIT, x)
	#define TK_RST_DIR(x) REG_SHADOW_SET(R_PORT_PB_DIR, port_pb_dir_shadow, CONFIG_ETRAX_DS1302_RSTBIT, x)
	#endif


	#define TK_SDA_OUT(x) REG_SHADOW_SET(R_PORT_PB_DATA, port_pb_data_shadow, CONFIG_ETRAX_DS1302_SDABIT, x)
	#define TK_SCL_OUT(x) REG_SHADOW_SET(R_PORT_PB_DATA, port_pb_data_shadow, CONFIG_ETRAX_DS1302_SCLBIT, x)

	#define TK_SDA_IN() ((*R_PORT_PB_READ >> CONFIG_ETRAX_DS1302_SDABIT) & 1)
	/* 1 is out, 0 is in */
	#define TK_SDA_DIR(x) REG_SHADOW_SET(R_PORT_PB_DIR, port_pb_dir_shadow, CONFIG_ETRAX_DS1302_SDABIT, x)
	#define TK_SCL_DIR(x) REG_SHADOW_SET(R_PORT_PB_DIR, port_pb_dir_shadow, CONFIG_ETRAX_DS1302_SCLBIT, x)


	/*
	* The reason for tempudelay and not udelay is that loops_per_usec
	* (used in udelay) is not set when functions here are called from time.c
	*/

	static void tempudelay(int usecs)
	{
	volatile int loops;

	for(loops = usecs * 12; loops > 0; loops--)
	/* nothing */;
	}


	/* Send 8 bits. */
	static void
	out_byte(unsigned char x)
	{
	int i;
	TK_SDA_DIR(1);
	for (i = 8; i--;) {
	/* The chip latches incoming bits on the rising edge of SCL. */
	TK_SCL_OUT(0);
	TK_SDA_OUT(x & 1);
	tempudelay(1);
	TK_SCL_OUT(1);
	tempudelay(1);
	x >>= 1;
	}
	TK_SDA_DIR(0);
	}

	static unsigned char
	in_byte(void)
	{
	unsigned char x = 0;
	int i;

	/* Read byte. Bits come LSB first, on the falling edge of SCL.
	* Assume SDA is in input direction already.
	*/
	TK_SDA_DIR(0);

	for (i = 8; i--;) {
	TK_SCL_OUT(0);
	tempudelay(1);
	x >>= 1;
	x \|= (TK_SDA_IN() << 7);
	TK_SCL_OUT(1);
	tempudelay(1);
	}

	return x;
	}

	/* Prepares for a transaction by de-activating RST (active-low). */

	static void
	start(void)
	{
	TK_SCL_OUT(0);
	tempudelay(1);
	TK_RST_OUT(0);
	tempudelay(5);
	TK_RST_OUT(1);
	}

	/* Ends a transaction by taking RST active again. */

	static void
	stop(void)
	{
	tempudelay(2);
	TK_RST_OUT(0);
	}

	/* Enable writing. */

	static void
	ds1302_wenable(void)
	{
	start();
	out_byte(0x8e); /* Write control register */
	out_byte(0x00); /* Disable write protect bit 7 = 0 */
	stop();
	}

	/* Disable writing. */

	static void
	ds1302_wdisable(void)
	{
	start();
	out_byte(0x8e); /* Write control register */
	out_byte(0x80); /* Disable write protect bit 7 = 0 */
	stop();
	}



	/* Read a byte from the selected register in the DS1302. */

	unsigned char
	ds1302_readreg(int reg)
	{
	unsigned char x;

	start();
	out_byte(0x81 \| (reg << 1)); /* read register */
	x = in_byte();
	stop();

	return x;
	}

	/* Write a byte to the selected register. */

	void
	ds1302_writereg(int reg, unsigned char val)
	{
	#ifndef CONFIG_ETRAX_RTC_READONLY
	int do_writereg = 1;
	#else
	int do_writereg = 0;

	if (reg == RTC_TRICKLECHARGER)
	do_writereg = 1;
	#endif

	if (do_writereg) {
	ds1302_wenable();
	start();
	out_byte(0x80 \| (reg << 1)); /* write register */
	out_byte(val);
	stop();
	ds1302_wdisable();
	}
	}

	void
	get_rtc_time(struct rtc_time *rtc_tm)
	{
	unsigned long flags;

	local_irq_save(flags);

	rtc_tm->tm_sec = CMOS_READ(RTC_SECONDS);
	rtc_tm->tm_min = CMOS_READ(RTC_MINUTES);
	rtc_tm->tm_hour = CMOS_READ(RTC_HOURS);
	rtc_tm->tm_mday = CMOS_READ(RTC_DAY_OF_MONTH);
	rtc_tm->tm_mon = CMOS_READ(RTC_MONTH);
	rtc_tm->tm_year = CMOS_READ(RTC_YEAR);

	local_irq_restore(flags);

	rtc_tm->tm_sec = bcd2bin(rtc_tm->tm_sec);
	rtc_tm->tm_min = bcd2bin(rtc_tm->tm_min);
	rtc_tm->tm_hour = bcd2bin(rtc_tm->tm_hour);
	rtc_tm->tm_mday = bcd2bin(rtc_tm->tm_mday);
	rtc_tm->tm_mon = bcd2bin(rtc_tm->tm_mon);
	rtc_tm->tm_year = bcd2bin(rtc_tm->tm_year);

	/*
	* Account for differences between how the RTC uses the values
	* and how they are defined in a struct rtc_time;
	*/

	if (rtc_tm->tm_year <= 69)
	rtc_tm->tm_year += 100;

	rtc_tm->tm_mon--;
	}

	static unsigned char days_in_mo[] =
	{0, 31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31};

	/* ioctl that supports RTC_RD_TIME and RTC_SET_TIME (read and set time/date). */

	static int
	rtc_ioctl(struct inode inode, struct file file, unsigned int cmd,
	unsigned long arg)
	{
	unsigned long flags;

	switch(cmd) {
	case RTC_RD_TIME: /* read the time/date from RTC */
	{
	struct rtc_time rtc_tm;

	memset(&rtc_tm, 0, sizeof (struct rtc_time));
	get_rtc_time(&rtc_tm);
	if (copy_to_user((struct rtc_time*)arg, &rtc_tm, sizeof(struct rtc_time)))
	return -EFAULT;
	return 0;
	}

	case RTC_SET_TIME: /* set the RTC */
	{
	struct rtc_time rtc_tm;
	unsigned char mon, day, hrs, min, sec, leap_yr;
	unsigned int yrs;

	if (!capable(CAP_SYS_TIME))
	return -EPERM;

	if (copy_from_user(&rtc_tm, (struct rtc_time*)arg, sizeof(struct rtc_time)))
	return -EFAULT;

	yrs = rtc_tm.tm_year + 1900;
	mon = rtc_tm.tm_mon + 1; /* tm_mon starts at zero */
	day = rtc_tm.tm_mday;
	hrs = rtc_tm.tm_hour;
	min = rtc_tm.tm_min;
	sec = rtc_tm.tm_sec;


	if ((yrs < 1970) \|\| (yrs > 2069))
	return -EINVAL;

	leap_yr = ((!(yrs % 4) && (yrs % 100)) \|\| !(yrs % 400));

	if ((mon > 12) \|\| (day == 0))
	return -EINVAL;

	if (day > (days_in_mo[mon] + ((mon == 2) && leap_yr)))
	return -EINVAL;

	if ((hrs >= 24) \|\| (min >= 60) \|\| (sec >= 60))
	return -EINVAL;

	if (yrs >= 2000)
	yrs -= 2000; /* RTC (0, 1, ... 69) */
	else
	yrs -= 1900; /* RTC (70, 71, ... 99) */

	sec = bin2bcd(sec);
	min = bin2bcd(min);
	hrs = bin2bcd(hrs);
	day = bin2bcd(day);
	mon = bin2bcd(mon);
	yrs = bin2bcd(yrs);

	local_irq_save(flags);
	CMOS_WRITE(yrs, RTC_YEAR);
	CMOS_WRITE(mon, RTC_MONTH);
	CMOS_WRITE(day, RTC_DAY_OF_MONTH);
	CMOS_WRITE(hrs, RTC_HOURS);
	CMOS_WRITE(min, RTC_MINUTES);
	CMOS_WRITE(sec, RTC_SECONDS);
	local_irq_restore(flags);

	/* Notice that at this point, the RTC is updated but
	* the kernel is still running with the old time.
	* You need to set that separately with settimeofday
	* or adjtimex.
	*/
	return 0;
	}

	case RTC_SET_CHARGE: /* set the RTC TRICKLE CHARGE register */
	{
	int tcs_val;

	if (!capable(CAP_SYS_TIME))
	return -EPERM;

	if(copy_from_user(&tcs_val, (int*)arg, sizeof(int)))
	return -EFAULT;

	tcs_val = RTC_TCR_PATTERN \| (tcs_val & 0x0F);
	ds1302_writereg(RTC_TRICKLECHARGER, tcs_val);
	return 0;
	}
	case RTC_VL_READ:
	{
	/* TODO:
	* Implement voltage low detection support
	*/
	printk(KERN_WARNING "DS1302: RTC Voltage Low detection"
	" is not supported\n");
	return 0;
	}
	case RTC_VL_CLR:
	{
	/* TODO:
	* Nothing to do since Voltage Low detection is not supported
	*/
	return 0;
	}
	default:
	return -ENOIOCTLCMD;
	}
	}

	static void
	print_rtc_status(void)
	{
	struct rtc_time tm;

	get_rtc_time(&tm);

	/*
	* There is no way to tell if the luser has the RTC set for local
	* time or for Universal Standard Time (GMT). Probably local though.
	*/

	printk(KERN_INFO "rtc_time\t: %02d:%02d:%02d\n",
	tm.tm_hour, tm.tm_min, tm.tm_sec);
	printk(KERN_INFO "rtc_date\t: %04d-%02d-%02d\n",
	tm.tm_year + 1900, tm.tm_mon + 1, tm.tm_mday);
	}

	/* The various file operations we support. */

	static const struct file_operations rtc_fops = {
	.owner = THIS_MODULE,
	.ioctl = rtc_ioctl,
	};

	/* Probe for the chip by writing something to its RAM and try reading it back. */

	#define MAGIC_PATTERN 0x42

	static int __init
	ds1302_probe(void)
	{
	int retval, res;

	TK_RST_DIR(1);
	TK_SCL_DIR(1);
	TK_SDA_DIR(0);

	/* Try to talk to timekeeper. */

	ds1302_wenable();
	start();
	out_byte(0xc0); /* write RAM byte 0 */
	out_byte(MAGIC_PATTERN); /* write something magic */
	start();
	out_byte(0xc1); /* read RAM byte 0 */

	if((res = in_byte()) == MAGIC_PATTERN) {
	stop();
	ds1302_wdisable();
	printk(KERN_INFO "%s: RTC found.\n", ds1302_name);
	printk(KERN_INFO "%s: SDA, SCL, RST on PB%i, PB%i, %s%i\n",
	ds1302_name,
	CONFIG_ETRAX_DS1302_SDABIT,
	CONFIG_ETRAX_DS1302_SCLBIT,
	#ifdef CONFIG_ETRAX_DS1302_RST_ON_GENERIC_PORT
	"GENIO",
	#else
	"PB",
	#endif
	CONFIG_ETRAX_DS1302_RSTBIT);
	print_rtc_status();
	retval = 1;
	} else {
	stop();
	retval = 0;
	}

	return retval;
	}


	/* Just probe for the RTC and register the device to handle the ioctl needed. */

	int __init
	ds1302_init(void)
	{
	#ifdef CONFIG_ETRAX_I2C
	i2c_init();
	#endif

	if (!ds1302_probe()) {
	#ifdef CONFIG_ETRAX_DS1302_RST_ON_GENERIC_PORT
	#if CONFIG_ETRAX_DS1302_RSTBIT == 27
	/*
	* The only way to set g27 to output is to enable ATA.
	*
	* Make sure that R_GEN_CONFIG is setup correct.
	*/
	/* Allocating the ATA interface will grab almost all
	* pins in I/O groups a, b, c and d. A consequence of
	* allocating the ATA interface is that the fixed
	* interfaces shared RAM, parallel port 0, parallel
	* port 1, parallel port W, SCSI-8 port 0, SCSI-8 port
	* 1, SCSI-W, serial port 2, serial port 3,
	* synchronous serial port 3 and USB port 2 and almost
	* all GPIO pins on port g cannot be used.
	*/
	if (cris_request_io_interface(if_ata, "ds1302/ATA")) {
	printk(KERN_WARNING "ds1302: Failed to get IO interface\n");
	return -1;
	}

	#elif CONFIG_ETRAX_DS1302_RSTBIT == 0
	if (cris_io_interface_allocate_pins(if_gpio_grp_a,
	'g',
	CONFIG_ETRAX_DS1302_RSTBIT,
	CONFIG_ETRAX_DS1302_RSTBIT)) {
	printk(KERN_WARNING "ds1302: Failed to get IO interface\n");
	return -1;
	}

	/* Set the direction of this bit to out. */
	genconfig_shadow = ((genconfig_shadow &
	~IO_MASK(R_GEN_CONFIG, g0dir)) \|
	(IO_STATE(R_GEN_CONFIG, g0dir, out)));
	*R_GEN_CONFIG = genconfig_shadow;
	#endif
	if (!ds1302_probe()) {
	printk(KERN_WARNING "%s: RTC not found.\n", ds1302_name);
	return -1;
	}
	#else
	printk(KERN_WARNING "%s: RTC not found.\n", ds1302_name);
	return -1;
	#endif
	}
	/* Initialise trickle charger */
	ds1302_writereg(RTC_TRICKLECHARGER,
	RTC_TCR_PATTERN \|(CONFIG_ETRAX_DS1302_TRICKLE_CHARGE & 0x0F));
	/* Start clock by resetting CLOCK_HALT */
	ds1302_writereg(RTC_SECONDS, (ds1302_readreg(RTC_SECONDS) & 0x7F));
	return 0;
	}

	static int __init ds1302_register(void)
	{
	ds1302_init();
	if (register_chrdev(RTC_MAJOR_NR, ds1302_name, &rtc_fops)) {
	printk(KERN_INFO "%s: unable to get major %d for rtc\n",
	ds1302_name, RTC_MAJOR_NR);
	return -1;
	}
	return 0;

	}

	module_init(ds1302_register);