#include "saa7146.h"
#if LINUX_VERSION_CODE < KERNEL_VERSION(2,5,51)
	#define KBUILD_MODNAME saa7146
#endif

/* helper function */
static
void my_wait(struct saa7146_dev *dev, long ms)
{
	set_current_state(TASK_INTERRUPTIBLE);
	schedule_timeout((((ms+10)/10)*HZ)/1000);
}

u32 saa7146_i2c_func(struct i2c_adapter *adapter)
{
//fm	DEB_I2C(("'%s'.\n", adapter->name));

	return	  I2C_FUNC_I2C
		| I2C_FUNC_SMBUS_QUICK
		| I2C_FUNC_SMBUS_READ_BYTE	| I2C_FUNC_SMBUS_WRITE_BYTE
		| I2C_FUNC_SMBUS_READ_BYTE_DATA | I2C_FUNC_SMBUS_WRITE_BYTE_DATA;
}

/* this function returns the status-register of our i2c-device */
static inline
u32 saa7146_i2c_status(struct saa7146_dev *dev) 
{
	u32 iicsta = saa7146_read(dev, I2C_STATUS);
/*
	DEB_I2C(("status: 0x%08x\n",iicsta));
*/
	return iicsta;
}

/* this function runs through the i2c-messages and prepares the data to be
   sent through the saa7146. have a look at the specifications p. 122 ff 
   to understand this. it returns the number of u32s to send, or -1
   in case of an error. */
static
int saa7146_i2c_msg_prepare(const struct i2c_msg m[], int num, u32 *op)
{
	int h1, h2;
	int i, j, addr;
	int mem = 0, op_count = 0;

	/* first determine size of needed memory */
	for(i = 0; i < num; i++) {
		mem += m[i].len + 1;
	}

	/* worst case: we need one u32 for three bytes to be send
	   plus one extra byte to address the device */
	mem = 1 + ((mem-1) / 3);

	/* we assume that op points to a memory of at least SAA7146_I2C_MEM bytes
	   size. if we exceed this limit... */
	if ( (4*mem) > SAA7146_I2C_MEM ) {
//fm		DEB_I2C(("cannot prepare i2c-message.\n"));
		return -ENOMEM;
	}

	/* be careful: clear out the i2c-mem first */
	memset(op,0,sizeof(u32)*mem);

	/* loop through all messages */
	for(i = 0; i < num; i++) {

		/* insert the address of the i2c-slave.
		   note: we get 7 bit i2c-addresses,
		   so we have to perform a translation */
		addr = (m[i].addr*2) + ( (0 != (m[i].flags & I2C_M_RD)) ? 1 : 0); 
		h1 = op_count/3; h2 = op_count%3;
		op[h1] |= (	    (u8)addr << ((3-h2)*8));
		op[h1] |= (SAA7146_I2C_START << ((3-h2)*2));
		op_count++;

		/* loop through all bytes of message i */
		for(j = 0; j < m[i].len; j++) {
			/* insert the data bytes */
			h1 = op_count/3; h2 = op_count%3;
			op[h1] |= ( (u32)((u8)m[i].buf[j]) << ((3-h2)*8));
			op[h1] |= (       SAA7146_I2C_CONT << ((3-h2)*2));
			op_count++;
		}
		
	}			

	/* have a look at the last byte inserted:
	  if it was: ...CONT change it to ...STOP */
	h1 = (op_count-1)/3; h2 = (op_count-1)%3;
	if ( SAA7146_I2C_CONT == (0x3 & (op[h1] >> ((3-h2)*2))) ) {
		op[h1] &= ~(0x2 << ((3-h2)*2));
		op[h1] |= (SAA7146_I2C_STOP << ((3-h2)*2));
	}

	/* return the number of u32s to send */	
	return mem;
}

/* this functions loops through all i2c-messages. normally, it should determine
   which bytes were read through the adapter and write them back to the corresponding
   i2c-message. but instead, we simply write back all bytes.
   fixme: this could be improved. */
static
int saa7146_i2c_msg_cleanup(const struct i2c_msg m[], int num, u32 *op)
{
	int i, j;
	int op_count = 0;

	/* loop through all messages */
	for(i = 0; i < num; i++) {

		op_count++;

		/* loop throgh all bytes of message i */
		for(j = 0; j < m[i].len; j++) {
			/* write back all bytes that could have been read */
			m[i].buf[j] = (op[op_count/3] >> ((3-(op_count%3))*8));
			op_count++;
		}
	}
	
	return 0;
}

/* this functions resets the i2c-device and returns 0 if everything was fine, otherwise -1 */
static
int saa7146_i2c_reset(struct saa7146_dev *dev) 
{
	/* get current status */
	u32 status = saa7146_i2c_status(dev);
	
	/* clear registers for sure */
	saa7146_write(dev, I2C_STATUS, dev->i2c_bitrate);
	saa7146_write(dev, I2C_TRANSFER, 0);

	/* check if any operation is still in progress */
	if ( 0 != ( status & SAA7146_I2C_BUSY) ) {

		/* yes, kill ongoing operation */
		DEB_I2C(("busy_state detected.\n"));

		/* set "ABORT-OPERATION"-bit (bit 7)*/
		saa7146_write(dev, I2C_STATUS, (dev->i2c_bitrate | MASK_07));
		saa7146_write(dev, MC2, (MASK_00 | MASK_16));
		my_wait(dev,SAA7146_I2C_DELAY);

		/* clear all error-bits pending; this is needed because p.123, note 1 */
		saa7146_write(dev, I2C_STATUS, dev->i2c_bitrate);
		saa7146_write(dev, MC2, (MASK_00 | MASK_16));
		my_wait(dev,SAA7146_I2C_DELAY);
 	}

	/* check if any error is (still) present. (this can be necessary because p.123, note 1) */
	status = saa7146_i2c_status(dev);

	if ( dev->i2c_bitrate != status ) {

		DEB_I2C(("error_state detected. status:0x%08x\n",status));

		/* Repeat the abort operation. This seems to be necessary
		   after serious protocol errors caused by e.g. the SAA7740 */
		saa7146_write(dev, I2C_STATUS, (dev->i2c_bitrate | MASK_07));
		saa7146_write(dev, MC2, (MASK_00 | MASK_16));
		my_wait(dev,SAA7146_I2C_DELAY);

		/* clear all error-bits pending */
		saa7146_write(dev, I2C_STATUS, dev->i2c_bitrate);
		saa7146_write(dev, MC2, (MASK_00 | MASK_16));
		my_wait(dev,SAA7146_I2C_DELAY);

		/* the data sheet says it might be necessary to clear the status
		   twice after an abort */
		saa7146_write(dev, I2C_STATUS, dev->i2c_bitrate);
		saa7146_write(dev, MC2, (MASK_00 | MASK_16));
		my_wait(dev,SAA7146_I2C_DELAY);
     	}

	/* if any error is still present, a fatal error has occured ... */
	status = saa7146_i2c_status(dev);
	if ( dev->i2c_bitrate != status ) {
		DEB_I2C(("fatal error. status:0x%08x\n",status));
		return -1;
	}

	return 0;
}

/* this functions writes out the data-byte 'dword' to the i2c-device.
   it returns 0 if ok, -1 if the transfer failed, -2 if the transfer
   failed badly (e.g. address error) */
static
int saa7146_i2c_writeout(struct saa7146_dev *dev, u32* dword)
{
	u32 status = 0, mc2 = 0;
	int timeout;

	/* write out i2c-command */
	DEB_I2C(("before: 0x%08x (status: 0x%08x), %d\n",*dword,saa7146_read(dev, I2C_STATUS), dev->i2c_op));

	if( 0 != (SAA7146_USE_I2C_IRQ & dev->ext->flags)) {

		saa7146_write(dev, I2C_STATUS,	 dev->i2c_bitrate);
		saa7146_write(dev, I2C_TRANSFER, *dword);

		dev->i2c_op = 1;
		IER_ENABLE(dev, MASK_16|MASK_17);
		saa7146_write(dev, MC2, (MASK_00 | MASK_16));

		wait_event_interruptible(dev->i2c_wq, dev->i2c_op == 0);
		if (signal_pending (current)) {
			/* a signal arrived */
			return -ERESTARTSYS;
		}
		status = saa7146_read(dev, I2C_STATUS);
	} else {
		saa7146_write(dev, I2C_STATUS,	 dev->i2c_bitrate);
		saa7146_write(dev, I2C_TRANSFER, *dword);
		saa7146_write(dev, MC2, (MASK_00 | MASK_16));

		/* do not poll for i2c-status before upload is complete */
		timeout = jiffies + HZ/100 + 1; /* 10ms */
		while(1) {
			mc2 = (saa7146_read(dev, MC2) & 0x1);
			if( 0 != mc2 ) {
				break;
			}
			if (jiffies > timeout) {
				printk(KERN_WARNING "saa7146_i2c_writeout: timed out waiting for MC2\n");
				return -EIO;
			}
		}
		/* wait until we get a transfer done or error */
		timeout = jiffies + HZ/100 + 1; /* 10ms */
		while(1) {
			status = saa7146_i2c_status(dev);
			if( (0x3 == (status & 0x3)) || (0 == (status & 0x1)) ) {
				break;
			}
			if (jiffies > timeout) {
				/* this is normal when probing the bus
				 * (no answer from nonexisistant device...)
				 */
				DEB_I2C(("saa7146_i2c_writeout: timed out waiting for end of xfer\n"));
				return -EIO;
			}
			my_wait(dev,1);
		}
	}

	/* give a detailed status report */
	if ( 0 != (status & SAA7146_I2C_ERR)) {

		if( 0 != (status & SAA7146_I2C_SPERR) ) {
			DEB_I2C(("error due to invalid start/stop condition.\n"));
		}
		if( 0 != (status & SAA7146_I2C_DTERR) ) {
			DEB_I2C(("error in data transmission.\n"));
		}
		if( 0 != (status & SAA7146_I2C_DRERR) ) {
			DEB_I2C(("error when receiving data.\n"));
		}
		if( 0 != (status & SAA7146_I2C_AL) ) {
			DEB_I2C(("error because arbitration lost.\n"));
		}

		/* we handle address-errors here */
		if( 0 != (status & SAA7146_I2C_APERR) ) {
			DEB_I2C(("error in address phase.\n"));
			return -EREMOTEIO;
		}

		return -EIO;
	}

	/* read back data, just in case we were reading ... */
	*dword = saa7146_read(dev, I2C_TRANSFER);

	DEB_I2C(("after: 0x%08x\n",*dword));
	return 0;
}

int saa7146_i2c_transfer(struct saa7146_dev *dev, const struct i2c_msg msgs[], int num, int retries)
{
	int i = 0, count = 0;
	u32* buffer = dev->i2c_mem;
	int err = 0;
	
	if (down_interruptible (&dev->i2c_lock))
		return -ERESTARTSYS;

	for(i=0;i<num;i++) {
		DEB_I2C(("msg:%d/%d\n",i+1,num));
	}
	
	/* prepare the message(s), get number of u32s to transfer */
	count = saa7146_i2c_msg_prepare(msgs, num, buffer);
	if ( 0 > count ) {
		err = -1;
		goto out;
	}

	do {
		/* reset the i2c-device if necessary */
		err = saa7146_i2c_reset(dev);
		if ( 0 > err ) {
			DEB_I2C(("could not reset i2c-device.\n"));
			goto out;
		}	

		/* write out the u32s one after another */
		for(i = 0; i < count; i++) {
			err = saa7146_i2c_writeout(dev, &buffer[i] );
			if ( 0 != err) {
				/* if address-error occured, donīt retry */
				if ( -EREMOTEIO == err ) {
					goto out;
				}
				DEB_I2C(("error while sending message(s). starting again.\n"));
				break;
			}
		}
		if( 0 == err ) {
			err = num;
			break;
		}
		
	} while (err != num && retries--);
	
	/* if any things had to be read, get the results */
	if ( 0 != saa7146_i2c_msg_cleanup(msgs, num, buffer)) {
		DEB_I2C(("could not cleanup i2c-message.\n"));
		err = -1;
		goto out;
	}

	/* another bug in revision 0: the i2c-registers get uploaded randomly by other
	   uploads, so we better clear them out before continueing */	
	if( 0 == dev->revision ) {
		u32 zero = 0;
		if( 0 != saa7146_i2c_writeout(dev, &zero)) {
			INFO(("revision 0 error. this should never happen.\n"));
		}
	}

	/* return the number of delivered messages */
	DEB_I2C(("transmission successful. (msg:%d).\n",err));
out:
	up(&dev->i2c_lock);
	return err;	
}

/* utility functions */
static
int saa7146_i2c_xfer(struct i2c_adapter* adapter, struct i2c_msg msg[], int num)
{
	struct saa7146_dev* dev = (struct saa7146_dev*)adapter->data;
	
	DEB_I2C(("adapter: '%s'.\n", adapter->name));
	
	/* use helper function to transfer data */
	return saa7146_i2c_transfer(dev, msg, num, adapter->retries);
}


/*****************************************************************************/
/* i2c-adapter helper functions                                              */
#include <linux/i2c-id.h>

/* exported algorithm data */
static
struct i2c_algorithm saa7146_algo = {
	.name		= "saa7146 i2c algorithm",
	.id		= I2C_ALGO_SAA7146,
	.master_xfer	= saa7146_i2c_xfer,
	.functionality	= saa7146_i2c_func,
};

int saa7146_i2c_adapter_prepare(struct saa7146_dev *dev, struct i2c_adapter *i2c_adapter, u32 bitrate)
{
	DEB_EE(("bitrate: 0x%08x\n",bitrate));
	
	dev->i2c_bitrate = bitrate;
	saa7146_i2c_reset(dev);

	if( NULL != i2c_adapter ) {
		memset(i2c_adapter,0,sizeof(struct i2c_adapter));
		strcpy(i2c_adapter->name, dev->name);	
		i2c_adapter->data	   = dev;
		i2c_adapter->algo	   = &saa7146_algo;
		i2c_adapter->algo_data     = NULL;
		i2c_adapter->id 	   = I2C_ALGO_SAA7146;
		i2c_adapter->timeout = SAA7146_I2C_TIMEOUT;
		i2c_adapter->retries = SAA7146_I2C_RETRIES;
	}
	
	return 0;
}