path: root/arch/powerpc/cpu/mpc8220/i2c.c

/*
 * (C) Copyright 2004, Freescale, Inc
 * TsiChung Liew, Tsi-Chung.Liew@freescale.com.
 *
 * See file CREDITS for list of people who contributed to this
 * project.
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License as
 * published by the Free Software Foundation; either version 2 of
 * the License, or (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place, Suite 330, Boston,
 * MA 02111-1307 USA
 */

#include <common.h>

DECLARE_GLOBAL_DATA_PTR;

#ifdef CONFIG_HARD_I2C

#include <mpc8220.h>
#include <i2c.h>

typedef struct mpc8220_i2c {
	volatile u32 adr;	/* I2Cn + 0x00 */
	volatile u32 fdr;	/* I2Cn + 0x04 */
	volatile u32 cr;	/* I2Cn + 0x08 */
	volatile u32 sr;	/* I2Cn + 0x0C */
	volatile u32 dr;	/* I2Cn + 0x10 */
} i2c_t;

/* I2Cn control register bits */
#define I2C_EN      0x80
#define I2C_IEN     0x40
#define I2C_STA     0x20
#define I2C_TX      0x10
#define I2C_TXAK    0x08
#define I2C_RSTA    0x04
#define I2C_INIT_MASK   (I2C_EN | I2C_STA | I2C_TX | I2C_RSTA)

/* I2Cn status register bits */
#define I2C_CF      0x80
#define I2C_AAS     0x40
#define I2C_BB      0x20
#define I2C_AL      0x10
#define I2C_SRW     0x04
#define I2C_IF      0x02
#define I2C_RXAK    0x01

#define I2C_TIMEOUT 100
#define I2C_RETRIES 1

struct mpc8220_i2c_tap {
	int scl2tap;
	int tap2tap;
};

static int mpc_reg_in (volatile u32 * reg);
static void mpc_reg_out (volatile u32 * reg, int val, int mask);
static int wait_for_bb (void);
static int wait_for_pin (int *status);
static int do_address (uchar chip, char rdwr_flag);
static int send_bytes (uchar chip, char *buf, int len);
static int receive_bytes (uchar chip, char *buf, int len);
static int mpc_get_fdr (int);

static int mpc_reg_in (volatile u32 * reg)
{
	int ret;
	ret = *reg >> 24;
	__asm__ __volatile__ ("eieio");
	return ret;
}

static void mpc_reg_out (volatile u32 * reg, int val, int mask)
{
	int tmp;

	if (!mask) {
		*reg = val << 24;
	} else {
		tmp = mpc_reg_in (reg);
		*reg = ((tmp & ~mask) | (val & mask)) << 24;
	}
	__asm__ __volatile__ ("eieio");

	return;
}

static int wait_for_bb (void)
{
	i2c_t *regs = (i2c_t *) MMAP_I2C;
	int timeout = I2C_TIMEOUT;
	int status;

	status = mpc_reg_in (&regs->sr);

	while (timeout-- && (status & I2C_BB)) {

		mpc_reg_out (&regs->cr, I2C_STA, I2C_STA);
		(void)mpc_reg_in (&regs->dr);
		mpc_reg_out (&regs->cr, 0, I2C_STA);
		mpc_reg_out (&regs->cr, 0, 0);
		mpc_reg_out (&regs->cr, I2C_EN, 0);

		udelay (1000);
		status = mpc_reg_in (&regs->sr);
	}

	return (status & I2C_BB);
}

static int wait_for_pin (int *status)
{
	i2c_t *regs = (i2c_t *) MMAP_I2C;
	int timeout = I2C_TIMEOUT;

	*status = mpc_reg_in (&regs->sr);

	while (timeout-- && !(*status & I2C_IF)) {
		udelay (1000);
		*status = mpc_reg_in (&regs->sr);
	}

	if (!(*status & I2C_IF)) {
		return -1;
	}

	mpc_reg_out (&regs->sr, 0, I2C_IF);
	return 0;
}

static int do_address (uchar chip, char rdwr_flag)
{
	i2c_t *regs = (i2c_t *) MMAP_I2C;
	int status;

	chip <<= 1;

	if (rdwr_flag)
		chip |= 1;

	mpc_reg_out (&regs->cr, I2C_TX, I2C_TX);
	mpc_reg_out (&regs->dr, chip, 0);

	if (wait_for_pin (&status))
		return -2;
	if (status & I2C_RXAK)
		return -3;
	return 0;
}

static int send_bytes (uchar chip, char *buf, int len)
{
	i2c_t *regs = (i2c_t *) MMAP_I2C;
	int wrcount;
	int status;

	for (wrcount = 0; wrcount < len; ++wrcount) {

		mpc_reg_out (&regs->dr, buf[wrcount], 0);

		if (wait_for_pin (&status))
			break;

		if (status & I2C_RXAK)
			break;

	}

	return !(wrcount == len);
	return 0;
}

static int receive_bytes (uchar chip, char *buf, int len)
{
	i2c_t *regs = (i2c_t *) MMAP_I2C;
	int dummy = 1;
	int rdcount = 0;
	int status;
	int i;

	mpc_reg_out (&regs->cr, 0, I2C_TX);

	for (i = 0; i < len; ++i) {
		buf[rdcount] = mpc_reg_in (&regs->dr);

		if (dummy)
			dummy = 0;
		else
			rdcount++;

		if (wait_for_pin (&status))
			return -4;
	}

	mpc_reg_out (&regs->cr, I2C_TXAK, I2C_TXAK);
	buf[rdcount++] = mpc_reg_in (&regs->dr);

	if (wait_for_pin (&status))
		return -5;

	mpc_reg_out (&regs->cr, 0, I2C_TXAK);
	return 0;
}

/**************** I2C API ****************/

void i2c_init (int speed, int saddr)
{
	i2c_t *regs = (i2c_t *) MMAP_I2C;

	mpc_reg_out (&regs->cr, 0, 0);
	mpc_reg_out (&regs->adr, saddr << 1, 0);

	/* Set clock
	 */
	mpc_reg_out (&regs->fdr, mpc_get_fdr (speed), 0);

	/* Enable module
	 */
	mpc_reg_out (&regs->cr, I2C_EN, I2C_INIT_MASK);
	mpc_reg_out (&regs->sr, 0, I2C_IF);
	return;
}

static int mpc_get_fdr (int speed)
{
	static int fdr = -1;

	if (fdr == -1) {
		ulong best_speed = 0;
		ulong divider;
		ulong ipb, scl;
		ulong bestmatch = 0xffffffffUL;
		int best_i = 0, best_j = 0, i, j;
		int SCL_Tap[] = { 9, 10, 12, 15, 5, 6, 7, 8 };
		struct mpc8220_i2c_tap scltap[] = {
			{4, 1},
			{4, 2},
			{6, 4},
			{6, 8},
			{14, 16},
			{30, 32},
			{62, 64},
			{126, 128}
		};

		ipb = gd->bus_clk;
		for (i = 7; i >= 0; i--) {
			for (j = 7; j >= 0; j--) {
				scl = 2 * (scltap[j].scl2tap +
					   (SCL_Tap[i] -
					    1) * scltap[j].tap2tap + 2);
				if (ipb <= speed * scl) {
					if ((speed * scl - ipb) < bestmatch) {
						bestmatch = speed * scl - ipb;
						best_i = i;
						best_j = j;
						best_speed = ipb / scl;
					}
				}
			}
		}
		divider = (best_i & 3) | ((best_i & 4) << 3) | (best_j << 2);
		if (gd->flags & GD_FLG_RELOC) {
			fdr = divider;
		} else {
			printf ("%ld kHz, ", best_speed / 1000);
			return divider;
		}
	}

	return fdr;
}

int i2c_probe (uchar chip)
{
	i2c_t *regs = (i2c_t *) MMAP_I2C;
	int i;

	for (i = 0; i < I2C_RETRIES; i++) {
		mpc_reg_out (&regs->cr, I2C_STA, I2C_STA);

		if (!do_address (chip, 0)) {
			mpc_reg_out (&regs->cr, 0, I2C_STA);
			break;
		}

		mpc_reg_out (&regs->cr, 0, I2C_STA);
		udelay (50);
	}

	return (i == I2C_RETRIES);
}

int i2c_read (uchar chip, uint addr, int alen, uchar * buf, int len)
{
	uchar xaddr[4];
	i2c_t *regs = (i2c_t *) MMAP_I2C;
	int ret = -1;

	xaddr[0] = (addr >> 24) & 0xFF;
	xaddr[1] = (addr >> 16) & 0xFF;
	xaddr[2] = (addr >> 8) & 0xFF;
	xaddr[3] = addr & 0xFF;

	if (wait_for_bb ()) {
		printf ("i2c_read: bus is busy\n");
		goto Done;
	}

	mpc_reg_out (&regs->cr, I2C_STA, I2C_STA);
	if (do_address (chip, 0)) {
		printf ("i2c_read: failed to address chip\n");
		goto Done;
	}

	if (send_bytes (chip, (char *)&xaddr[4 - alen], alen)) {
		printf ("i2c_read: send_bytes failed\n");
		goto Done;
	}

	mpc_reg_out (&regs->cr, I2C_RSTA, I2C_RSTA);
	if (do_address (chip, 1)) {
		printf ("i2c_read: failed to address chip\n");
		goto Done;
	}

	if (receive_bytes (chip, (char *)buf, len)) {
		printf ("i2c_read: receive_bytes failed\n");
		goto Done;
	}

	ret = 0;
      Done:
	mpc_reg_out (&regs->cr, 0, I2C_STA);
	return ret;
}

int i2c_write (uchar chip, uint addr, int alen, uchar * buf, int len)
{
	uchar xaddr[4];
	i2c_t *regs = (i2c_t *) MMAP_I2C;
	int ret = -1;

	xaddr[0] = (addr >> 24) & 0xFF;
	xaddr[1] = (addr >> 16) & 0xFF;
	xaddr[2] = (addr >> 8) & 0xFF;
	xaddr[3] = addr & 0xFF;

	if (wait_for_bb ()) {
		printf ("i2c_write: bus is busy\n");
		goto Done;
	}

	mpc_reg_out (&regs->cr, I2C_STA, I2C_STA);
	if (do_address (chip, 0)) {
		printf ("i2c_write: failed to address chip\n");
		goto Done;
	}

	if (send_bytes (chip, (char *)&xaddr[4 - alen], alen)) {
		printf ("i2c_write: send_bytes failed\n");
		goto Done;
	}

	if (send_bytes (chip, (char *)buf, len)) {
		printf ("i2c_write: send_bytes failed\n");
		goto Done;
	}

	ret = 0;
      Done:
	mpc_reg_out (&regs->cr, 0, I2C_STA);
	return ret;
}

#endif /* CONFIG_HARD_I2C */