/*
 * Time of Day Clock support for the M48T35, M48T37, M48T59, and MC146818
 * Real Time Clocks/Timekeepers.
 *
 * Author: Mark A. Greer <mgreer@mvista.com>
 *
 * 2001-2004 (c) MontaVista, Software, Inc.  This file is licensed under
 * the terms of the GNU General Public License version 2.  This program
 * is licensed "as is" without any warranty of any kind, whether express
 * or implied.
 */
#include <linux/errno.h>
#include <linux/init.h>
#include <linux/kernel.h>
#include <linux/time.h>
#include <linux/timex.h>
#include <linux/bcd.h>
#include <linux/mc146818rtc.h>

#include <asm/machdep.h>
#include <asm/io.h>
#include <asm/time.h>
#include <asm/todc.h>

/*
 * Depending on the hardware on your board and your board design, the
 * RTC/NVRAM may be accessed either directly (like normal memory) or via
 * address/data registers.  If your board uses the direct method, set
 * 'nvram_data' to the base address of your nvram and leave 'nvram_as0' and
 * 'nvram_as1' NULL.  If your board uses address/data regs to access nvram,
 * set 'nvram_as0' to the address of the lower byte, set 'nvram_as1' to the
 * address of the upper byte (leave NULL if using mc146818), and set
 * 'nvram_data' to the address of the 8-bit data register.
 *
 * Note: Even though the documentation for the various RTC chips say that it
 * 	 take up to a second before it starts updating once the 'R' bit is
 * 	 cleared, they always seem to update even though we bang on it many
 * 	 times a second.  This is true, except for the Dallas Semi 1746/1747
 * 	 (possibly others).  Those chips seem to have a real problem whenever
 * 	 we set the 'R' bit before reading them, they basically stop counting.
 * 	 					--MAG
 */

/*
 * 'todc_info' should be initialized in your *_setup.c file to
 * point to a fully initialized 'todc_info_t' structure.
 * This structure holds all the register offsets for your particular
 * TODC/RTC chip.
 * TODC_ALLOC()/TODC_INIT() will allocate and initialize this table for you.
 */

#ifdef	RTC_FREQ_SELECT
#undef	RTC_FREQ_SELECT
#define	RTC_FREQ_SELECT		control_b	/* Register A */
#endif

#ifdef	RTC_CONTROL
#undef	RTC_CONTROL
#define	RTC_CONTROL		control_a	/* Register B */
#endif

#ifdef	RTC_INTR_FLAGS
#undef	RTC_INTR_FLAGS
#define	RTC_INTR_FLAGS		watchdog	/* Register C */
#endif

#ifdef	RTC_VALID
#undef	RTC_VALID
#define	RTC_VALID		interrupts	/* Register D */
#endif

/* Access routines when RTC accessed directly (like normal memory) */
u_char
todc_direct_read_val(int addr)
{
	return readb((void __iomem *)(todc_info->nvram_data + addr));
}

void
todc_direct_write_val(int addr, unsigned char val)
{
	writeb(val, (void __iomem *)(todc_info->nvram_data + addr));
	return;
}

/* Access routines for accessing m48txx type chips via addr/data regs */
u_char
todc_m48txx_read_val(int addr)
{
	outb(addr, todc_info->nvram_as0);
	outb(addr>>todc_info->as0_bits, todc_info->nvram_as1);
	return inb(todc_info->nvram_data);
}

void
todc_m48txx_write_val(int addr, unsigned char val)
{
	outb(addr, todc_info->nvram_as0);
	outb(addr>>todc_info->as0_bits, todc_info->nvram_as1);
	outb(val, todc_info->nvram_data);
	return;
}

/* Access routines for accessing mc146818 type chips via addr/data regs */
u_char
todc_mc146818_read_val(int addr)
{
	outb_p(addr, todc_info->nvram_as0);
	return inb_p(todc_info->nvram_data);
}

void
todc_mc146818_write_val(int addr, unsigned char val)
{
	outb_p(addr, todc_info->nvram_as0);
	outb_p(val, todc_info->nvram_data);
}


/*
 * Routines to make RTC chips with NVRAM buried behind an addr/data pair
 * have the NVRAM and clock regs appear at the same level.
 * The NVRAM will appear to start at addr 0 and the clock regs will appear
 * to start immediately after the NVRAM (actually, start at offset
 * todc_info->nvram_size).
 */
static inline u_char
todc_read_val(int addr)
{
	u_char	val;

	if (todc_info->sw_flags & TODC_FLAG_2_LEVEL_NVRAM) {
		if (addr < todc_info->nvram_size) { /* NVRAM */
			ppc_md.rtc_write_val(todc_info->nvram_addr_reg, addr);
			val = ppc_md.rtc_read_val(todc_info->nvram_data_reg);
		} else { /* Clock Reg */
			addr -= todc_info->nvram_size;
			val = ppc_md.rtc_read_val(addr);
		}
	} else
		val = ppc_md.rtc_read_val(addr);

	return val;
}

static inline void
todc_write_val(int addr, u_char val)
{
	if (todc_info->sw_flags & TODC_FLAG_2_LEVEL_NVRAM) {
		if (addr < todc_info->nvram_size) { /* NVRAM */
			ppc_md.rtc_write_val(todc_info->nvram_addr_reg, addr);
			ppc_md.rtc_write_val(todc_info->nvram_data_reg, val);
		} else { /* Clock Reg */
			addr -= todc_info->nvram_size;
			ppc_md.rtc_write_val(addr, val);
		}
	} else
		ppc_md.rtc_write_val(addr, val);
}

/*
 * TODC routines
 *
 * There is some ugly stuff in that there are assumptions for the mc146818.
 *
 * Assumptions:
 *	- todc_info->control_a has the offset as mc146818 Register B reg
 *	- todc_info->control_b has the offset as mc146818 Register A reg
 *	- m48txx control reg's write enable or 'W' bit is same as
 *	  mc146818 Register B 'SET' bit (i.e., 0x80)
 *
 * These assumptions were made to make the code simpler.
 */
long __init
todc_time_init(void)
{
	u_char	cntl_b;

	if (!ppc_md.rtc_read_val)
		ppc_md.rtc_read_val = ppc_md.nvram_read_val;
	if (!ppc_md.rtc_write_val)
		ppc_md.rtc_write_val = ppc_md.nvram_write_val;

	cntl_b = todc_read_val(todc_info->control_b);

	if (todc_info->rtc_type == TODC_TYPE_MC146818) {
		if ((cntl_b & 0x70) != 0x20) {
			printk(KERN_INFO "TODC real-time-clock was stopped."
				"  Now starting...");
			cntl_b &= ~0x70;
			cntl_b |= 0x20;
		}

		todc_write_val(todc_info->control_b, cntl_b);
	} else if (todc_info->rtc_type == TODC_TYPE_DS17285) {
		u_char mode;

		mode = todc_read_val(TODC_TYPE_DS17285_CNTL_A);
		/* Make sure countdown clear is not set */
		mode &= ~0x40;
		/* Enable oscillator, extended register set */
		mode |= 0x30;
		todc_write_val(TODC_TYPE_DS17285_CNTL_A, mode);

	} else if (todc_info->rtc_type == TODC_TYPE_DS1501) {
		u_char	month;

		todc_info->enable_read = TODC_DS1501_CNTL_B_TE;
		todc_info->enable_write = TODC_DS1501_CNTL_B_TE;

		month = todc_read_val(todc_info->month);

		if ((month & 0x80) == 0x80) {
			printk(KERN_INFO "TODC %s %s\n",
				"real-time-clock was stopped.",
				"Now starting...");
			month &= ~0x80;
			todc_write_val(todc_info->month, month);
		}

		cntl_b &= ~TODC_DS1501_CNTL_B_TE;
		todc_write_val(todc_info->control_b, cntl_b);
	} else { /* must be a m48txx type */
		u_char	cntl_a;

		todc_info->enable_read = TODC_MK48TXX_CNTL_A_R;
		todc_info->enable_write = TODC_MK48TXX_CNTL_A_W;

		cntl_a = todc_read_val(todc_info->control_a);

		/* Check & clear STOP bit in control B register */
		if (cntl_b & TODC_MK48TXX_DAY_CB) {
			printk(KERN_INFO "TODC %s %s\n",
				"real-time-clock was stopped.",
				"Now starting...");

			cntl_a |= todc_info->enable_write;
			cntl_b &= ~TODC_MK48TXX_DAY_CB;/* Start Oscil */

			todc_write_val(todc_info->control_a, cntl_a);
			todc_write_val(todc_info->control_b, cntl_b);
		}

		/* Make sure READ & WRITE bits are cleared. */
		cntl_a &= ~(todc_info->enable_write | todc_info->enable_read);
		todc_write_val(todc_info->control_a, cntl_a);
	}

	return 0;
}

/*
 * There is some ugly stuff in that there are assumptions that for a mc146818,
 * the todc_info->control_a has the offset of the mc146818 Register B reg and
 * that the register'ss 'SET' bit is the same as the m48txx's write enable
 * bit in the control register of the m48txx (i.e., 0x80).
 *
 * It was done to make the code look simpler.
 */
void
todc_get_rtc_time(struct rtc_time *tm)
{
	uint	year = 0, mon = 0, mday = 0, hour = 0, min = 0, sec = 0;
	uint	limit, i;
	u_char	save_control, uip = 0;
	extern void GregorianDay(struct rtc_time *);

	spin_lock(&rtc_lock);
	save_control = todc_read_val(todc_info->control_a);

	if (todc_info->rtc_type != TODC_TYPE_MC146818) {
		limit = 1;

		switch (todc_info->rtc_type) {
		case TODC_TYPE_DS1553:
		case TODC_TYPE_DS1557:
		case TODC_TYPE_DS1743:
		case TODC_TYPE_DS1746:	/* XXXX BAD HACK -> FIX */
		case TODC_TYPE_DS1747:
		case TODC_TYPE_DS17285:
			break;
		default:
			todc_write_val(todc_info->control_a,
				(save_control | todc_info->enable_read));
		}
	} else
		limit = 100000000;

	for (i=0; i<limit; i++) {
		if (todc_info->rtc_type == TODC_TYPE_MC146818)
			uip = todc_read_val(todc_info->RTC_FREQ_SELECT);

		sec = todc_read_val(todc_info->seconds) & 0x7f;
		min = todc_read_val(todc_info->minutes) & 0x7f;
		hour = todc_read_val(todc_info->hours) & 0x3f;
		mday = todc_read_val(todc_info->day_of_month) & 0x3f;
		mon = todc_read_val(todc_info->month) & 0x1f;
		year = todc_read_val(todc_info->year) & 0xff;

		if (todc_info->rtc_type == TODC_TYPE_MC146818) {
			uip |= todc_read_val(todc_info->RTC_FREQ_SELECT);
			if ((uip & RTC_UIP) == 0)
				break;
		}
	}

	if (todc_info->rtc_type != TODC_TYPE_MC146818) {
		switch (todc_info->rtc_type) {
		case TODC_TYPE_DS1553:
		case TODC_TYPE_DS1557:
		case TODC_TYPE_DS1743:
		case TODC_TYPE_DS1746:	/* XXXX BAD HACK -> FIX */
		case TODC_TYPE_DS1747:
		case TODC_TYPE_DS17285:
			break;
		default:
			save_control &= ~(todc_info->enable_read);
			todc_write_val(todc_info->control_a, save_control);
		}
	}
	spin_unlock(&rtc_lock);

	if ((todc_info->rtc_type != TODC_TYPE_MC146818)
			|| ((save_control & RTC_DM_BINARY) == 0)
			|| RTC_ALWAYS_BCD) {
		BCD_TO_BIN(sec);
		BCD_TO_BIN(min);
		BCD_TO_BIN(hour);
		BCD_TO_BIN(mday);
		BCD_TO_BIN(mon);
		BCD_TO_BIN(year);
	}

	if ((year + 1900) < 1970) {
		year += 100;
	}

	tm->tm_sec = sec;
	tm->tm_min = min;
	tm->tm_hour = hour;
	tm->tm_mday = mday;
	tm->tm_mon = mon;
	tm->tm_year = year;

	GregorianDay(tm);
}

int
todc_set_rtc_time(struct rtc_time *tm)
{
	u_char save_control, save_freq_select = 0;

	spin_lock(&rtc_lock);
	save_control = todc_read_val(todc_info->control_a);

	/* Assuming MK48T59_RTC_CA_WRITE & RTC_SET are equal */
	todc_write_val(todc_info->control_a,
		(save_control | todc_info->enable_write));
	save_control &= ~(todc_info->enable_write); /* in case it was set */

	if (todc_info->rtc_type == TODC_TYPE_MC146818) {
		save_freq_select = todc_read_val(todc_info->RTC_FREQ_SELECT);
		todc_write_val(todc_info->RTC_FREQ_SELECT,
			save_freq_select | RTC_DIV_RESET2);
	}

	if ((todc_info->rtc_type != TODC_TYPE_MC146818)
			|| ((save_control & RTC_DM_BINARY) == 0)
			|| RTC_ALWAYS_BCD) {
		BIN_TO_BCD(tm->tm_sec);
		BIN_TO_BCD(tm->tm_min);
		BIN_TO_BCD(tm->tm_hour);
		BIN_TO_BCD(tm->tm_mon);
		BIN_TO_BCD(tm->tm_mday);
		BIN_TO_BCD(tm->tm_year);
	}

	todc_write_val(todc_info->seconds, tm->tm_sec);
	todc_write_val(todc_info->minutes, tm->tm_min);
	todc_write_val(todc_info->hours, tm->tm_hour);
	todc_write_val(todc_info->month, tm->tm_mon);
	todc_write_val(todc_info->day_of_month, tm->tm_mday);
	todc_write_val(todc_info->year, tm->tm_year);

	todc_write_val(todc_info->control_a, save_control);

	if (todc_info->rtc_type == TODC_TYPE_MC146818)
		todc_write_val(todc_info->RTC_FREQ_SELECT, save_freq_select);

	spin_unlock(&rtc_lock);
	return 0;
}