ds1302.c

linux2.6.16版本

/*!***************************************************************************
*!
*! 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/config.h>

#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