drivers/i2c/busses/i2c-c2k.c

#include <config.h>
#include <init.h>
#include <common.h>
#include <malloc.h>
#include <i2c/i2c.h>
#include <asm/io.h>
#include <mach/gpio.h>
#include <mach/comcerto-2000.h>
#include <mach/i2c.h>

#define DEFAULT_BUS_FREQ	100000

static bool is_initialized = false;

/* Assuming that there is only one master on the bus (us) */

static void i2c_init (struct device_d *pdev)
{
	unsigned int n, m, freq, margin, power;
	unsigned int actualN = 0, actualM = 0;
	unsigned int minMargin = 0xffffffff;
	unsigned int control, status;
	unsigned int tclk = CFG_TCLK;
	unsigned int i2cFreq = DEFAULT_BUS_FREQ;
	struct i2c_platform_data *pdata = pdev->platform_data;
	if (pdata && pdata->bitrate)
		i2cFreq = pdata->bitrate;

	dev_dbg(pdev, "i2c_init\n");

	for (n = 0; n < 8; n++) {
		for (m = 0; m < 16; m++) {
			power = 1 << n;	/* power = 2^(n) */
			freq = tclk / (10 * (m + 1) * power);
			if (i2cFreq > freq)
				margin = i2cFreq - freq;
			else
				margin = freq - i2cFreq;
			if (margin < minMargin) {
				minMargin = margin;
				actualN = n;
				actualM = m;
			}
		}
	}

	dev_dbg(pdev, "setup i2c bus\n");

	/* Setup bus */
        writel(0, pdev->map_base + I2C_SOFT_RESET);

	dev_dbg(pdev, "udelay...\n");

	udelay (I2C_DELAY);

	dev_dbg(pdev, "set baudrate\n");

	writel((actualM << 3) | actualN, pdev->map_base + I2C_STAT);
	writel(I2C_AAK | I2C_ENAB, pdev->map_base + I2C_CNTR);

	udelay (I2C_DELAY * 10);

	dev_dbg(pdev, "read control, baudrate\n");

	status = readl(pdev->map_base + I2C_STAT);
	control = readl(pdev->map_base + I2C_CNTR);

	is_initialized = true;
}

static uchar i2c_start (struct device_d *pdev)
{
	unsigned int control, status;
	int count = 0;

	/* Set the start bit */
	control = readl(pdev->map_base + I2C_CNTR);
	control |= I2C_STA;	/* generate the I2C_START_BIT */
	writel(control, pdev->map_base + I2C_CNTR);

	status = readl(pdev->map_base + I2C_STAT);

	count = 0;
	while ((status & 0xff) != I2C_START_TRANSMIT) {
		udelay (I2C_DELAY);
		if (count > 20) {
			writel(I2C_STP, pdev->map_base + I2C_CNTR);	/*stop */
			dev_dbg(pdev, "i2c_start status timeout: 0x%x\n", status);
			return (status);
		}
		status = readl(pdev->map_base + I2C_STAT);
		dev_dbg(pdev, "i2c_start status 0x%x\n", status);
		count++;
	}

	return (0);
}

static uchar i2c_select_device (struct device_d *pdev, uchar dev_addr, uchar read, int ten_bit)
{
	unsigned int status, data, bits = 7;
	int count = 0;

	/* Output slave address */
	if (ten_bit) {
		bits = 10;
	}

	data = (dev_addr << 1);
	/* set the read bit */
	data |= read;
	writel(data, pdev->map_base + I2C_DATA);
	/* assert the address */
	writel(readl(pdev->map_base + I2C_CNTR) & ~I2C_IFLG, pdev->map_base + I2C_CNTR);

	udelay (I2C_DELAY);

	status = readl(pdev->map_base + I2C_STAT);
	count = 0;
	while (((status & 0xff) != I2C_ADDRESS_R_ACK) && ((status & 0xff) != I2C_ADDRESS_W_ACK)) {
		udelay (I2C_DELAY);
		if (count > 20) {
			writel(I2C_STP, pdev->map_base + I2C_CNTR);	/*stop */
			dev_dbg(pdev, "i2c_select_device timeout status 0x%x\n",status);
			return (status);
		}
		status = readl(pdev->map_base + I2C_STAT);
		dev_dbg(pdev, "i2c_select_device status 0x%x\n",status);
		count++;
	}

	if (bits == 10) {
		dev_dbg(pdev, "10 bit I2C addressing not yet implemented\n");
		return (0xff);
	}

	return (0);
}

static uchar i2c_get_data (struct device_d *pdev, uchar *return_data, int len)
{

	unsigned int data, status = 0;
	int count = 0;
	uint32_t ack_expected = I2C_DATA_RECEIVE_ACK;

	while (len) {
		count = 0;

		if (len > 1) {
			/* more data to read, acknowledge the received byte */
			writel(I2C_AAK, pdev->map_base + I2C_CNTR);
                } else {
			/* last byte, don't send acknowledge */
			writel(0, pdev->map_base + I2C_CNTR);
			ack_expected = I2C_DATA_RECEIVE_NACK;
		}

		udelay (I2C_DELAY * 5);

		status = readl(pdev->map_base + I2C_STAT);
		dev_dbg(pdev, "i2c_get_data len %d status 0x%x\n", len, status);
		while ((status & 0xff) != ack_expected) {
			udelay (I2C_DELAY * 10000);
			if (count > 40) {
				writel(I2C_STP, pdev->map_base + I2C_CNTR);	/*stop */
				dev_dbg(pdev, "i2c_get_data timeout status 0x%x\n", status);
				return 0;
			}
			status = readl(pdev->map_base + I2C_STAT);
			dev_dbg(pdev, "i2c_get_data status 0x%x\n", status);
			count++;
		}
		data = readl(pdev->map_base + I2C_DATA);
		len--;
		*return_data = (uchar) data;
		return_data++;
		dev_dbg(pdev, "i2c_get_data data 0x%x\n",data);
	}
	writel(I2C_STP, pdev->map_base + I2C_CNTR);	/* stop */

	return (0);
}

/* created this function to get the i2c_write() */
/* function working properly. */
/* function to write bytes out on the i2c bus */
/* */
/* returns 0 = success */
/*         anything other than zero is failure */
static uchar i2c_write_byte (struct device_d *pdev, unsigned char *data, int len)
{
	unsigned int status;
	int count = 0;
	unsigned int temp;
	unsigned char *temp_ptr = data;

	dev_dbg(pdev, "i2c_write_byte  data 0x%x\n", *temp_ptr);

	while (len) {
		if (!(len % 128))
			printf("#");
		/* Set and assert the data */
		temp = *temp_ptr;
		writel(temp, pdev->map_base + I2C_DATA);
		writel(readl(pdev->map_base + I2C_CNTR) & ~I2C_IFLG, pdev->map_base + I2C_CNTR);

		udelay (I2C_DELAY*2);

		status = readl(pdev->map_base + I2C_STAT);
		count++;
		while ((status & 0xff) != I2C_DATA_TRANSMIT_ACK) {
			udelay (I2C_DELAY*2000);
			if (count > 20) {
				writel(I2C_STP, pdev->map_base + I2C_CNTR);	/*stop */
				return (status);
			}
			status = readl(pdev->map_base + I2C_STAT);
			count++;
			dev_dbg(pdev, "i2c_write_byte  status 0x%x\n",status);
		}
		len--;
		temp_ptr++;
	}

	return (0);
}

uchar i2c_read (struct device_d *pdev, uchar dev_addr, uchar * data, int len)
{
	uchar status = 0;

	status = i2c_start (pdev);

	if (status) {
		dev_dbg(pdev, "Transaction start failed: 0x%02x\n", status);
		return status;
	}

	status = i2c_select_device (pdev, dev_addr, 1, 0);	/* send the slave address */
	if (status) {
		dev_dbg(pdev, "Address not acknowledged: 0x%02x\n", status);
		return status;
	}

	status = i2c_get_data (pdev, data, len);
	if (status) {
		dev_dbg(pdev, "Data not recieved: 0x%02x\n", status);
		return status;
	}

	return 0;
}

/* Function to set the I2C stop bit */
void i2c_stop (struct device_d *pdev)
{
	writel((0x1 << 4), pdev->map_base + I2C_CNTR);
}

/* I2C write function */
/* dev_addr = device address */
/* data = pointer to the data to send */
/* len = # of bytes to send */
/* */
/* returns 0 = succesful */
/*         anything but zero is failure */
uchar i2c_write (struct device_d *pdev, uchar dev_addr, uchar * data, int len)
{
	uchar status = 0;

	status = i2c_start (pdev);	/* send a start bit */

	if (status) {
		dev_dbg(pdev, "Transaction start failed: 0x%02x\n", status);
		return status;
	}

	status = i2c_select_device (pdev, dev_addr, 0, 0);
	if (status) {
		dev_dbg(pdev, "Failed to set slave address: 0x%02x\n", status);
		return status;
	}

	status = i2c_write_byte (pdev, data, len);	/* write the data */
	if (status) {
		dev_dbg(pdev, "Data not written: 0x%02x\n", status);
		return status;
	}
	/* issue a stop bit */
	i2c_stop (pdev);
	return 0;
}

static int i2c_c2k_xfer(struct i2c_adapter *adapter, struct i2c_msg *msgs, int num)
{
        int i;
        int result;

	if (!is_initialized) {
		i2c_init(adapter->dev);
	}

	for (i = 0; i < num; i++) {
		if (msgs[i].flags & I2C_M_RD)
			result = i2c_read(adapter->dev, msgs[i].addr,
					msgs[i].buf, msgs[i].len);
		else
			result = i2c_write(adapter->dev, msgs[i].addr,
					msgs[i].buf, msgs[i].len);

		if (result)
			break;
	}

	return (result < 0) ? result : num;
}

/* function to determine if an I2C device is present */
/* chip = device address of chip to check for */
/* */
/* returns 0 = sucessful, the device exists */
/*         anything other than zero is failure, no device */
static int i2c_probe (struct device_d *pdev)
{
	uchar status = 0;
	struct i2c_adapter *adapter;

	dev_dbg(pdev, "i2c_probe\n");

	adapter = kzalloc(sizeof(struct i2c_adapter), GFP_KERNEL);

	adapter->master_xfer = i2c_c2k_xfer;
	adapter->nr = pdev->id;
	adapter->dev = pdev;

	/* Add I2C adapter */
	status = i2c_add_numbered_adapter(adapter);
	if (status < 0)
	{
		dev_err(pdev, "registration failed\n");
		kfree(adapter);
		return status;
	}

	return 0;		/* successful completion */
}

static struct driver_d c2k_i2c_driver = {
        .name    = "c2k_i2c",
        .probe   = i2c_probe,
};

static int c2k_i2c_driverinit(void)
{
        return register_driver(&c2k_i2c_driver);
}

device_initcall(c2k_i2c_driverinit);