/*!***************************************************************************
*!
*! 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/mutex.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 DEFINE_MUTEX(ds1302_mutex);
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 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 long rtc_unlocked_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
{
        int ret;

        mutex_lock(&ds1302_mutex);
        ret = rtc_ioctl(file, cmd, arg);
        mutex_unlock(&ds1302_mutex);

        return ret;
}

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,
        .unlocked_ioctl = rtc_unlocked_ioctl,
        .llseek         = noop_llseek,
}; 

/* 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);