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ds1302.c

/*!***************************************************************************
*!
*! FILE NAME  : ds1302.c
*!
*! DESCRIPTION: Implements an interface for the DS1302 RTC through Etrax I/O
*!
*! Functions exported: ds1302_readreg, ds1302_writereg, ds1302_init
*!
*! $Log: ds1302.c,v $
*! Revision 1.18  2005/01/24 09:11:26  mikaelam
*! Minor changes to get DS1302 RTC chip driver to work
*!
*! Revision 1.17  2005/01/05 06:11:22  starvik
*! No need to do local_irq_disable after local_irq_save.
*!
*! Revision 1.16  2004/12/13 12:21:52  starvik
*! Added I/O and DMA allocators from Linux 2.4
*!
*! Revision 1.14  2004/08/24 06:48:43  starvik
*! Whitespace cleanup
*!
*! Revision 1.13  2004/05/28 09:26:59  starvik
*! Modified I2C initialization to work in 2.6.
*!
*! Revision 1.12  2004/05/14 07:58:03  starvik
*! Merge of changes from 2.4
*!
*! Revision 1.10  2004/02/04 09:25:12  starvik
*! Merge of Linux 2.6.2
*!
*! Revision 1.9  2003/07/04 08:27:37  starvik
*! Merge of Linux 2.5.74
*!
*! Revision 1.8  2003/04/09 05:20:47  starvik
*! Merge of Linux 2.5.67
*!
*! Revision 1.6  2003/01/09 14:42:51  starvik
*! Merge of Linux 2.5.55
*!
*! Revision 1.4  2002/12/11 13:13:57  starvik
*! Added arch/ to v10 specific includes
*! Added fix from Linux 2.4 in serial.c (flush_to_flip_buffer)
*!
*! Revision 1.3  2002/11/20 11:56:10  starvik
*! Merge of Linux 2.5.48
*!
*! Revision 1.2  2002/11/18 13:16:06  starvik
*! Linux 2.5 port of latest 2.4 drivers
*!
*! Revision 1.15  2002/10/11 16:14:33  johana
*! Added CONFIG_ETRAX_DS1302_TRICKLE_CHARGE and initial setting of the
*! trcklecharge register.
*!
*! Revision 1.14  2002/10/10 12:15:38  magnusmn
*! Added support for having the RST signal on bit g0
*!
*! Revision 1.13  2002/05/29 15:16:08  johana
*! Removed unused variables.
*!
*! Revision 1.12  2002/04/10 15:35:25  johana
*! Moved probe function closer to init function and marked it __init.
*!
*! Revision 1.11  2001/06/14 12:35:52  jonashg
*! The ATA hack is back. It is unfortunately the only way to set g27 to output.
*!
*! Revision 1.9  2001/06/14 10:00:14  jonashg
*! No need for tempudelay to be inline anymore (had to adjust the usec to
*! loops conversion because of this to make it slow enough to be a udelay).
*!
*! Revision 1.8  2001/06/14 08:06:32  jonashg
*! Made tempudelay delay usecs (well, just a tad more).
*!
*! Revision 1.7  2001/06/13 14:18:11  jonashg
*! Only allow processes with SYS_TIME capability to set time and charge.
*!
*! Revision 1.6  2001/06/12 15:22:07  jonashg
*! * Made init function __init.
*! * Parameter to out_byte() is unsigned char.
*! * The magic number 42 has got a name.
*! * Removed comment about /proc (nothing is exported there).
*!
*! Revision 1.5  2001/06/12 14:35:13  jonashg
*! Gave the module a name and added it to printk's.
*!
*! Revision 1.4  2001/05/31 14:53:40  jonashg
*! Made tempudelay() inline so that the watchdog doesn't reset (see
*! function comment).
*!
*! Revision 1.3  2001/03/26 16:03:06  bjornw
*! Needs linux/config.h
*!
*! Revision 1.2  2001/03/20 19:42:00  bjornw
*! Use the ETRAX prefix on the DS1302 options
*!
*! Revision 1.1  2001/03/20 09:13:50  magnusmn
*! Linux 2.4 port
*!
*! Revision 1.10  2000/07/05 15:38:23  bjornw
*! Dont update kernel time when a RTC_SET_TIME is done
*!
*! Revision 1.9  2000/03/02 15:42:59  macce
*! * Hack to make RTC work on all 2100/2400
*!
*! Revision 1.8  2000/02/23 16:59:18  torbjore
*! added setup of R_GEN_CONFIG when RTC is connected to the generic port.
*!
*! Revision 1.7  2000/01/17 15:51:43  johana
*! Added RTC_SET_CHARGE ioctl to enable trickle charger.
*!
*! Revision 1.6  1999/10/27 13:19:47  bjornw
*! Added update_xtime_from_cmos which reads back the updated RTC into the kernel.
*! /dev/rtc calls it now.
*!
*! Revision 1.5  1999/10/27 12:39:37  bjornw
*! Disabled superuser check. Anyone can now set the time.
*!
*! Revision 1.4  1999/09/02 13:27:46  pkj
*! Added shadow for R_PORT_PB_CONFIG.
*! Renamed port_g_shadow to port_g_data_shadow.
*!
*! Revision 1.3  1999/09/02 08:28:06  pkj
*! Made it possible to select either port PB or the generic port for the RST
*! signal line to the DS1302 RTC.
*! Also make sure the RST bit is configured as output on Port PB (if used).
*!
*! Revision 1.2  1999/09/01 14:47:20  bjornw
*! Added support for /dev/rtc operations with ioctl RD_TIME and SET_TIME to read
*! and set the date. Register as major 121.
*!
*! Revision 1.1  1999/09/01 09:45:29  bjornw
*! Implemented a DS1302 RTC driver.
*!
*!
*! ---------------------------------------------------------------------------
*!
*! (C) Copyright 1999, 2000, 2001, 2002, 2003, 2004  Axis Communications AB, LUND, SWEDEN
*!
*! $Id: ds1302.c,v 1.18 2005/01/24 09:11:26 mikaelam Exp $
*!
*!***************************************************************************/


#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 <asm/arch/svinto.h>
#include <asm/io.h>
#include <asm/rtc.h>
#include <asm/arch/io_interface_mux.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);
      
      BCD_TO_BIN(rtc_tm->tm_sec);
      BCD_TO_BIN(rtc_tm->tm_min);
      BCD_TO_BIN(rtc_tm->tm_hour);
      BCD_TO_BIN(rtc_tm->tm_mday);
      BCD_TO_BIN(rtc_tm->tm_mon);
      BCD_TO_BIN(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) */

                  BIN_TO_BCD(sec);
                  BIN_TO_BCD(min);
                  BIN_TO_BCD(hrs);
                  BIN_TO_BCD(day);
                  BIN_TO_BCD(mon);
                  BIN_TO_BCD(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_VLOW_RD:
            {
                  /* TODO:
                   * Implement voltage low detection support
                   */
                  printk(KERN_WARNING "DS1302: RTC Voltage Low detection"
                         " is not supported\n");
                  return 0;
            }
            case RTC_VLOW_SET:
            {
                  /* 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 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);

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