pt7c4372a_rtc.c

linux kernel RTC driver program with pt7c4372a_ic

/*
 *  @file	pt7c4372a_rtc.c
 *  @brief	t30x RTC
 *
 *	$Id: pt7c4372a_rtc.c,v 1.2 2008/05/09 09:27:39 gary Exp $
 *  $Author: gary $
 *  $Revision: 1.2 $
 *
 *	Copyright (c) 2008 Inc. All rights reserved.
 *
 *	@date	2008/04/24	gary	new file.
 *			2008/05/09  gary	setup control register 2 properly.
 *
 */

#include <linux/init.h>
#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/time.h>
#include <linux/timer.h>

#include <asm/io.h>
#include <asm/time.h>
#include <asm/mach-t30x/t30x.h>
#include <asm/mach-t30x/gpio.h>
#include <asm/mach-t30x/ostimer.h>

#define PT_RTC_VER	"1.01"

/* pt7c4372a register definitions. */
#define REG_SEC			0x0
#define REG_MIN			0x1
#define REG_HOUR		0x2
#define REG_DAYWEEK		0x3
#define REG_DAYS		0x4
#define REG_MON			0x5
#define REG_YEAR		0x6
#define REG_TIME_TRIM	0x7
#if 0
/* no need for now */
#define REG_ALARMA_MIN	0x8
#define REG_ALARMA_HOUR	0x9
#define REG_ALARMA_DAY	0xa
#define REG_ALARMB_MIN	0xb
#define REG_ALARMB_HOUR	0xc
#define REG_ALARMB_DAY	0xd
#endif
#define REG_CTRL1		0xe
#define REG_CTRL2		0xf

/* address 0y0110010, + read 0x65, + write 0x64 */
#define ADDR        0x32
#define I2C_READ    0x01
#define I2C_WRITE   0x00

void t30x_udelay(int offset)
{
    unsigned long timeout = readl(T30X_OSTIMER_OSCR) + offset;
    unsigned long current_cnt;
    
    while ( (signed)(timeout - (current_cnt = readl(T30X_OSTIMER_OSCR)))>0 );
}

static int ostimer_offset;

/*
 * GPIO operation functions.
 */
void t30x_set_gpio_2(int state)
{
    if ( state )
        writel(0x0004, GPIO_SET);
    else
        writel(0x0004, GPIO_CLEAR);
}

void t30x_set_gpio_3(int state)
{
    if ( state )
        writel(0x0008, GPIO_SET);
    else
        writel(0x0008, GPIO_CLEAR);
}

int t30x_get_gpio_3(void)
{
    return (readl(GPIO_LEVEL)&0x0008) ? 1 : 0;
} 

void t30x_set_gpio_oe_3(int oe)
{
    if ( oe ) { /* output enabled */
        t30x_set_gpio_3(1);
        writel(readl(GPIO_OE)|0x0008, GPIO_OE);
    } else {
        t30x_set_gpio_3(0);
        writel(readl(GPIO_OE)&(~0x0008), GPIO_OE);
    }
}

/* gpio-2 SCL, gpio-3 SDA */ 
#define setsda(val) t30x_set_gpio_3(val)
#define getsda()	t30x_get_gpio_3()
#define setscl(val) t30x_set_gpio_2(val)
#define sda_to_read()	t30x_set_gpio_oe_3(0)
#define sda_to_write()	t30x_set_gpio_oe_3(1)

static inline void sdalo(void)
{
    t30x_udelay(ostimer_offset);
	setsda(0);
	t30x_udelay(ostimer_offset);
}

static inline void sdahi(void)
{
    t30x_udelay(ostimer_offset);
	setsda(1);
	t30x_udelay(ostimer_offset);
	
}

static inline void scllo(void)
{
    t30x_udelay(ostimer_offset);
	setscl(0);
	t30x_udelay(ostimer_offset);
}

static inline void sclhi(void)
{
    t30x_udelay(ostimer_offset);
	setscl(1);
	t30x_udelay(ostimer_offset);
}

static void i2c_start(void)
{
	sdalo();
	scllo();
}

#if 0
static void i2c_repstart(void)
{
	setsda(1);
	sclhi();
    t30x_udelay(ostimer_offset);

	sdalo();
	scllo();
}
#endif

static void i2c_stop(void)
{
	sdalo();
	sclhi();
	sdahi();
}

static int i2c_outb(char c)
{
	int i;
	int sb;
	int ack;

	/* assert: scl is low */
	for ( i=7; i>=0; i-- ) {
		sb = c & ( 1 << i );
		setsda(sb);
		t30x_udelay(ostimer_offset);
		sclhi();
		/* do arbitration here:
		 * if ( sb && ! getsda(adap) ) -> ouch! Get out of here.
		 */
		setscl(0);
		t30x_udelay(ostimer_offset);
	}
	sda_to_read();
	sclhi();
	/* read ack: SDA should be pulled down by slave */
	ack=getsda();	/* ack: sda is pulled low ->success. */
	scllo();
	sda_to_write();
	return 0==ack;		/* return 1 if device acked	 */
	/* assert: scl is low (sda undef) */
}

static int i2c_inb(void)
{
	/* read byte via i2c port, without start/stop sequence	*/
	/* acknowledge is sent in i2c_read.			*/
	int i;
	unsigned char indata=0;

	/* assert: scl is low */
//	sdahi();
	sda_to_read();
	for (i=0;i<8;i++) {
	    sclhi();
		indata *= 2;
		if ( getsda() )
			indata |= 0x01;
		scllo();
	}
	/* assert: scl is low */
	sda_to_write();
	return (int) (indata & 0xff);
}

static unsigned char read_reg(unsigned char reg)
{
    int rc;
    unsigned char data = 0;
    unsigned long flags;
    spinlock_t lock;
    
    spin_lock_init(&lock);
    spin_lock_irqsave(&lock, flags);

    i2c_start();
    
    rc = i2c_outb(ADDR<<1 | I2C_WRITE);
    if ( !rc )
        printk("pt_rtc read_reg no ack 1\n");
    rc = i2c_outb((reg<<4 | 0x04));
    if ( !rc )
        printk("pt_rtc read_reg no ack 2\n");

    rc = i2c_inb();
    
    data |= (rc&0xff);

    /* n-ack */    
    sdahi();
    sclhi();
    scllo();
    
    i2c_stop();
    
    spin_unlock_irqrestore(&lock, flags);
    
    return data;
}

static int write_reg(unsigned char reg, unsigned char val)
{
    int rc;
    unsigned long flags;
    spinlock_t lock;
    
    spin_lock_init(&lock);
    spin_lock_irqsave(&lock, flags);

    i2c_start();
    
    rc = i2c_outb(ADDR<<1 | I2C_WRITE);
    if ( !rc )
        printk("pt_rtc write_reg ack 1 failed\n");
    rc = i2c_outb((reg<<4|0x00));
    if ( !rc )
        printk("pt_rtc write_reg ack 2 failed\n");
    rc = i2c_outb((unsigned char)(val & 0xff));
    if ( !rc )
        printk("pt_rtc write_reg ack 4 failed\n");

    i2c_stop();

    spin_unlock_irqrestore(&lock, flags);
    
    return rc;
}

inline int bcd2bin(int s)
{
    return ( ((s>>4)&0x0f)*10 + (s&0x0f) );
}

inline int bin2bcd(int s)
{
    return ( ((s/10)*16) + (s%10) );
}
 
unsigned long pt_rtc_get_time(void)
{
    unsigned int sec, min, hrs, day, mon, yrs;
    
    while ( 1 ) {
        sec = read_reg(REG_SEC)&0x7f;
        min = read_reg(REG_MIN)&0x7f;
        hrs = read_reg(REG_HOUR)&0x3f;
        day = read_reg(REG_DAYS)&0x3f;
        mon = read_reg(REG_MON)&0x1f;
        yrs = (read_reg(REG_YEAR)&0xff);
        if ( sec == 0x59 && sec != (read_reg(REG_SEC)&0x7f) )
            continue;
        else
            break;
    }
    
    sec = bcd2bin(sec);
    min = bcd2bin(min);
    hrs = bcd2bin(hrs);
    day = bcd2bin(day);
    mon = bcd2bin(mon);
    yrs = bcd2bin(yrs) + 2000;
        
    return mktime(yrs, mon, day, hrs, min, sec);
}

int pt_rtc_set_time(unsigned long time)
{
    struct rtc_time tm;
    
    to_tm(time, &tm);
    tm.tm_mon += 1;
    tm.tm_year -= 2000;
    
    write_reg(REG_YEAR, bin2bcd(tm.tm_year));
    write_reg(REG_MON, bin2bcd(tm.tm_mon));
    write_reg(REG_DAYS, bin2bcd(tm.tm_mday));
    write_reg(REG_HOUR, bin2bcd(tm.tm_hour));
    write_reg(REG_MIN, bin2bcd(tm.tm_min));
    write_reg(REG_SEC, bin2bcd(tm.tm_sec));
    
    return 0;
}

void __init pt_rtc_init(void)
{
#ifdef CONFIG_T307_OSTIMER
#error "PT7C4372A driver would use T30x OSTIMER... failed..."
#endif
    /* print driver banner. */
    printk("Use PT7C4372A as external RTC, driver ver. %s\n", PT_RTC_VER);
    
    /* set up bit [14:15] to 0x00 for GPIO 2, 3 usage */
    writel(readl(GPIO_ALTFUNC_SEL)&(~0xc000), GPIO_ALTFUNC_SEL);
    /* disable gpio 2, 3 interrupt mask */
    writel(readl(GPIO_INT_MASK)|0x0c, GPIO_INT_MASK);
    /* setup gpio 2, 3 to 1 */
    writel(0x0c, GPIO_SET);
    /* setup output enabled to 1 for default output */
    writel(readl(GPIO_OE)|0x0c, GPIO_OE);
    
    writel(0x0f, T30X_OSTIMER_OSIMR);
    writel(0, T30X_OSTIMER_OSCCD);
    ostimer_offset = 10;
    
    write_reg(REG_CTRL2, 0x20);
}