xref: /openbmc/u-boot/drivers/i2c/fsl_i2c.c (revision d8c82db482d6b535d12b419d6440b88bf7091c9b)

/*
 * Copyright 2006 Freescale Semiconductor, Inc.
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License
 * Version 2 as published by the Free Software Foundation.
 *
 * 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>

#ifdef CONFIG_FSL_I2C
#ifdef CONFIG_HARD_I2C

#include <command.h>
#include <i2c.h>		/* Functional interface */

#include <asm/io.h>
#include <asm/fsl_i2c.h>	/* HW definitions */

#define I2C_TIMEOUT	(CFG_HZ / 4)

#define I2C_READ_BIT  1
#define I2C_WRITE_BIT 0

DECLARE_GLOBAL_DATA_PTR;

/* Initialize the bus pointer to whatever one the SPD EEPROM is on.
 * Default is bus 0.  This is necessary because the DDR initialization
 * runs from ROM, and we can't switch buses because we can't modify
 * the global variables.
 */
#ifdef CFG_SPD_BUS_NUM
static unsigned int i2c_bus_num __attribute__ ((section ("data"))) = CFG_SPD_BUS_NUM;
#else
static unsigned int i2c_bus_num __attribute__ ((section ("data"))) = 0;
#endif

static unsigned int i2c_bus_speed[2] = {CFG_I2C_SPEED, CFG_I2C_SPEED};

static const struct fsl_i2c *i2c_dev[2] = {
	(struct fsl_i2c *) (CFG_IMMR + CFG_I2C_OFFSET),
#ifdef CFG_I2C2_OFFSET
	(struct fsl_i2c *) (CFG_IMMR + CFG_I2C2_OFFSET)
#endif
};

/* I2C speed map for a DFSR value of 1 */

/*
 * Map I2C frequency dividers to FDR and DFSR values
 *
 * This structure is used to define the elements of a table that maps I2C
 * frequency divider (I2C clock rate divided by I2C bus speed) to a value to be
 * programmed into the Frequency Divider Ratio (FDR) and Digital Filter
 * Sampling Rate (DFSR) registers.
 *
 * The actual table should be defined in the board file, and it must be called
 * fsl_i2c_speed_map[].
 *
 * The last entry of the table must have a value of {-1, X}, where X is same
 * FDR/DFSR values as the second-to-last entry.  This guarantees that any
 * search through the array will always find a match.
 *
 * The values of the divider must be in increasing numerical order, i.e.
 * fsl_i2c_speed_map[x+1].divider > fsl_i2c_speed_map[x].divider.
 *
 * For this table, the values are based on a value of 1 for the DFSR
 * register.  See the application note AN2919 "Determining the I2C Frequency
 * Divider Ratio for SCL"
 */
static const struct {
	unsigned short divider;
	u8 dfsr;
	u8 fdr;
} fsl_i2c_speed_map[] = {
	{160, 1, 32}, {192, 1, 33}, {224, 1, 34}, {256, 1, 35},
	{288, 1, 0}, {320, 1, 1}, {352, 6, 1}, {384, 1, 2}, {416, 6, 2},
	{448, 1, 38}, {480, 1, 3}, {512, 1, 39}, {544, 11, 3}, {576, 1, 4},
	{608, 22, 3}, {640, 1, 5}, {672, 32, 3}, {704, 11, 5}, {736, 43, 3},
	{768, 1, 6}, {800, 54, 3}, {832, 11, 6}, {896, 1, 42}, {960, 1, 7},
	{1024, 1, 43}, {1088, 22, 7}, {1152, 1, 8}, {1216, 43, 7}, {1280, 1, 9},
	{1408, 22, 9}, {1536, 1, 10}, {1664, 22, 10}, {1792, 1, 46},
	{1920, 1, 11}, {2048, 1, 47}, {2176, 43, 11}, {2304, 1, 12},
	{2560, 1, 13}, {2816, 43, 13}, {3072, 1, 14}, {3328, 43, 14},
	{3584, 1, 50}, {3840, 1, 15}, {4096, 1, 51}, {4608, 1, 16},
	{5120, 1, 17}, {6144, 1, 18}, {7168, 1, 54}, {7680, 1, 19},
	{8192, 1, 55}, {9216, 1, 20}, {10240, 1, 21}, {12288, 1, 22},
	{14336, 1, 58}, {15360, 1, 23}, {16384, 1, 59}, {18432, 1, 24},
	{20480, 1, 25}, {24576, 1, 26}, {28672, 1, 62}, {30720, 1, 27},
	{32768, 1, 63}, {36864, 1, 28}, {40960, 1, 29}, {49152, 1, 30},
	{61440, 1, 31}, {-1, 1, 31}
};

/**
 * Set the I2C bus speed for a given I2C device
 *
 * @param dev: the I2C device
 * @i2c_clk: I2C bus clock frequency
 * @speed: the desired speed of the bus
 *
 * The I2C device must be stopped before calling this function.
 *
 * The return value is the actual bus speed that is set.
 */
static unsigned int set_i2c_bus_speed(const struct fsl_i2c *dev,
	unsigned int i2c_clk, unsigned int speed)
{
	unsigned short divider = min(i2c_clk / speed, (unsigned short) -1);
	unsigned int i;
	u8 fdr, dfsr;

	/*
	 * We want to choose an FDR/DFSR that generates an I2C bus speed that
	 * is equal to or lower than the requested speed.  That means that we
	 * want the first divider that is equal to or greater than the
	 * calculated divider.
	 */

	for (i = 0; i < ARRAY_SIZE(fsl_i2c_speed_map); i++)
		if (fsl_i2c_speed_map[i].divider >= divider) {
			dfsr = fsl_i2c_speed_map[i].dfsr;
			fdr = fsl_i2c_speed_map[i].fdr;
			speed = i2c_clk / fsl_i2c_speed_map[i].divider;
			break;
		}

	writeb(fdr, &dev->fdr);			/* set bus speed */
	writeb(dfsr, &dev->dfsrr);		/* set default filter */

	return speed;
}

void
i2c_init(int speed, int slaveadd)
{
	struct fsl_i2c *dev;

	dev = (struct fsl_i2c *) (CFG_IMMR + CFG_I2C_OFFSET);

	writeb(0, &dev->cr);			/* stop I2C controller */
	udelay(5);				/* let it shutdown in peace */
	i2c_bus_speed[0] = set_i2c_bus_speed(dev, gd->i2c1_clk, speed);
	writeb(slaveadd << 1, &dev->adr);	/* write slave address */
	writeb(0x0, &dev->sr);			/* clear status register */
	writeb(I2C_CR_MEN, &dev->cr);		/* start I2C controller */

#ifdef	CFG_I2C2_OFFSET
	dev = (struct fsl_i2c *) (CFG_IMMR + CFG_I2C2_OFFSET);

	writeb(0, &dev->cr);			/* stop I2C controller */
	udelay(5);				/* let it shutdown in peace */
	i2c_bus_speed[1] = set_i2c_bus_speed(dev, gd->i2c2_clk, speed);
	writeb(slaveadd << 1, &dev->adr);	/* write slave address */
	writeb(0x0, &dev->sr);			/* clear status register */
	writeb(I2C_CR_MEN, &dev->cr);		/* start I2C controller */
#endif
}

static __inline__ int
i2c_wait4bus(void)
{
	ulong timeval = get_timer(0);

	while (readb(&i2c_dev[i2c_bus_num]->sr) & I2C_SR_MBB) {
		if (get_timer(timeval) > I2C_TIMEOUT) {
			return -1;
		}
	}

	return 0;
}

static __inline__ int
i2c_wait(int write)
{
	u32 csr;
	ulong timeval = get_timer(0);

	do {
		csr = readb(&i2c_dev[i2c_bus_num]->sr);
		if (!(csr & I2C_SR_MIF))
			continue;

		writeb(0x0, &i2c_dev[i2c_bus_num]->sr);

		if (csr & I2C_SR_MAL) {
			debug("i2c_wait: MAL\n");
			return -1;
		}

		if (!(csr & I2C_SR_MCF))	{
			debug("i2c_wait: unfinished\n");
			return -1;
		}

		if (write == I2C_WRITE_BIT && (csr & I2C_SR_RXAK)) {
			debug("i2c_wait: No RXACK\n");
			return -1;
		}

		return 0;
	} while (get_timer (timeval) < I2C_TIMEOUT);

	debug("i2c_wait: timed out\n");
	return -1;
}

static __inline__ int
i2c_write_addr (u8 dev, u8 dir, int rsta)
{
	writeb(I2C_CR_MEN | I2C_CR_MSTA | I2C_CR_MTX
	       | (rsta ? I2C_CR_RSTA : 0),
	       &i2c_dev[i2c_bus_num]->cr);

	writeb((dev << 1) | dir, &i2c_dev[i2c_bus_num]->dr);

	if (i2c_wait(I2C_WRITE_BIT) < 0)
		return 0;

	return 1;
}

static __inline__ int
__i2c_write(u8 *data, int length)
{
	int i;

	writeb(I2C_CR_MEN | I2C_CR_MSTA | I2C_CR_MTX,
	       &i2c_dev[i2c_bus_num]->cr);

	for (i = 0; i < length; i++) {
		writeb(data[i], &i2c_dev[i2c_bus_num]->dr);

		if (i2c_wait(I2C_WRITE_BIT) < 0)
			break;
	}

	return i;
}

static __inline__ int
__i2c_read(u8 *data, int length)
{
	int i;

	writeb(I2C_CR_MEN | I2C_CR_MSTA | ((length == 1) ? I2C_CR_TXAK : 0),
	       &i2c_dev[i2c_bus_num]->cr);

	/* dummy read */
	readb(&i2c_dev[i2c_bus_num]->dr);

	for (i = 0; i < length; i++) {
		if (i2c_wait(I2C_READ_BIT) < 0)
			break;

		/* Generate ack on last next to last byte */
		if (i == length - 2)
			writeb(I2C_CR_MEN | I2C_CR_MSTA | I2C_CR_TXAK,
			       &i2c_dev[i2c_bus_num]->cr);

		/* Generate stop on last byte */
		if (i == length - 1)
			writeb(I2C_CR_MEN | I2C_CR_TXAK, &i2c_dev[i2c_bus_num]->cr);

		data[i] = readb(&i2c_dev[i2c_bus_num]->dr);
	}

	return i;
}

int
i2c_read(u8 dev, uint addr, int alen, u8 *data, int length)
{
	int i = -1; /* signal error */
	u8 *a = (u8*)&addr;

	if (i2c_wait4bus() >= 0
	    && i2c_write_addr(dev, I2C_WRITE_BIT, 0) != 0
	    && __i2c_write(&a[4 - alen], alen) == alen)
		i = 0; /* No error so far */

	if (length
	    && i2c_write_addr(dev, I2C_READ_BIT, 1) != 0)
		i = __i2c_read(data, length);

	writeb(I2C_CR_MEN, &i2c_dev[i2c_bus_num]->cr);

	if (i == length)
	    return 0;

	return -1;
}

int
i2c_write(u8 dev, uint addr, int alen, u8 *data, int length)
{
	int i = -1; /* signal error */
	u8 *a = (u8*)&addr;

	if (i2c_wait4bus() >= 0
	    && i2c_write_addr(dev, I2C_WRITE_BIT, 0) != 0
	    && __i2c_write(&a[4 - alen], alen) == alen) {
		i = __i2c_write(data, length);
	}

	writeb(I2C_CR_MEN, &i2c_dev[i2c_bus_num]->cr);

	if (i == length)
	    return 0;

	return -1;
}

int
i2c_probe(uchar chip)
{
	/* For unknow reason the controller will ACK when
	 * probing for a slave with the same address, so skip
	 * it.
	 */
	if (chip == (readb(&i2c_dev[i2c_bus_num]->adr) >> 1))
		return -1;

	return i2c_read(chip, 0, 0, NULL, 0);
}

uchar
i2c_reg_read(uchar i2c_addr, uchar reg)
{
	uchar buf[1];

	i2c_read(i2c_addr, reg, 1, buf, 1);

	return buf[0];
}

void
i2c_reg_write(uchar i2c_addr, uchar reg, uchar val)
{
	i2c_write(i2c_addr, reg, 1, &val, 1);
}

int i2c_set_bus_num(unsigned int bus)
{
#ifdef CFG_I2C2_OFFSET
	if (bus > 1) {
#else
	if (bus > 0) {
#endif
		return -1;
	}

	i2c_bus_num = bus;

	return 0;
}

int i2c_set_bus_speed(unsigned int speed)
{
	unsigned int i2c_clk = (i2c_bus_num == 1) ? gd->i2c2_clk : gd->i2c1_clk;

	writeb(0, &i2c_dev[i2c_bus_num]->cr);		/* stop controller */
	i2c_bus_speed[i2c_bus_num] =
		set_i2c_bus_speed(i2c_dev[i2c_bus_num], i2c_clk, speed);
	writeb(I2C_CR_MEN, &i2c_dev[i2c_bus_num]->cr);	/* start controller */

	return 0;
}

unsigned int i2c_get_bus_num(void)
{
	return i2c_bus_num;
}

unsigned int i2c_get_bus_speed(void)
{
	return i2c_bus_speed[i2c_bus_num];
}

#endif /* CONFIG_HARD_I2C */
#endif /* CONFIG_FSL_I2C */