i2c-core.c

《linux驱动程序设计从入门到精通》一书中所有的程序代码含驱动和相应的应用程序

int i2c_smbus_check_pec(u16 addr, u8 command, int size, u8 partial,
                        union i2c_smbus_data *data)
{
	u8 buf[3], rpec, cpec;

	buf[1] = command;
	switch(size) {
		case I2C_SMBUS_BYTE_DATA:
			buf[0] = (addr << 1) | 1;
			cpec = i2c_smbus_pec(2, buf, NULL);
			rpec = data->byte;
			break;
		case I2C_SMBUS_WORD_DATA:
			buf[0] = (addr << 1) | 1;
			buf[2] = data->word & 0xff;
			cpec = i2c_smbus_pec(3, buf, NULL);
			rpec = data->word >> 8;
			break;
		case I2C_SMBUS_WORD_DATA_PEC:
			/* unsupported */
			cpec = rpec = 0;
			break;
		case I2C_SMBUS_PROC_CALL_PEC:
			/* unsupported */
			cpec = rpec = 0;
			break;
		case I2C_SMBUS_BLOCK_DATA_PEC:
			buf[0] = (addr << 1);
			buf[2] = (addr << 1) | 1;
			cpec = i2c_smbus_pec(3, buf, data->block);
			rpec = data->block[data->block[0] + 1];
			break;
		case I2C_SMBUS_BLOCK_PROC_CALL_PEC:
			buf[0] = (addr << 1) | 1;
			rpec = i2c_smbus_partial_pec(partial, 1,
			                             buf, data->block);
			cpec = data->block[data->block[0] + 1];
			break;
		default:
			cpec = rpec = 0;
			break;
	}
	if (rpec != cpec) {
		pr_debug("i2c-core: Bad PEC 0x%02x vs. 0x%02x\n",
			rpec, cpec);
		return -1;
	}
	return 0;	
}

s32 i2c_smbus_write_quick(struct i2c_client *client, u8 value)
{
	return i2c_smbus_xfer(client->adapter,client->addr,client->flags,
 	                      value,0,I2C_SMBUS_QUICK,NULL);
}

s32 i2c_smbus_read_byte(struct i2c_client *client)
{
	union i2c_smbus_data data;
	if (i2c_smbus_xfer(client->adapter,client->addr,client->flags,
	                   I2C_SMBUS_READ,0,I2C_SMBUS_BYTE, &data))
		return -1;
	else
		return 0x0FF & data.byte;
}

s32 i2c_smbus_write_byte(struct i2c_client *client, u8 value)
{
	union i2c_smbus_data data;	/* only for PEC */
	return i2c_smbus_xfer(client->adapter,client->addr,client->flags,
	                      I2C_SMBUS_WRITE,value, I2C_SMBUS_BYTE,&data);
}

s32 i2c_smbus_read_byte_data(struct i2c_client *client, u8 command)
{
	union i2c_smbus_data data;
	if (i2c_smbus_xfer(client->adapter,client->addr,client->flags,
	                   I2C_SMBUS_READ,command, I2C_SMBUS_BYTE_DATA,&data))
		return -1;
	else
		return 0x0FF & data.byte;
}

s32 i2c_smbus_write_byte_data(struct i2c_client *client, u8 command, u8 value)
{
	union i2c_smbus_data data;
	data.byte = value;
	return i2c_smbus_xfer(client->adapter,client->addr,client->flags,
	                      I2C_SMBUS_WRITE,command,
	                      I2C_SMBUS_BYTE_DATA,&data);
}

s32 i2c_smbus_read_word_data(struct i2c_client *client, u8 command)
{
	union i2c_smbus_data data;
	if (i2c_smbus_xfer(client->adapter,client->addr,client->flags,
	                   I2C_SMBUS_READ,command, I2C_SMBUS_WORD_DATA, &data))
		return -1;
	else
		return 0x0FFFF & data.word;
}

s32 i2c_smbus_write_word_data(struct i2c_client *client, u8 command, u16 value)
{
	union i2c_smbus_data data;
	data.word = value;
	return i2c_smbus_xfer(client->adapter,client->addr,client->flags,
	                      I2C_SMBUS_WRITE,command,
	                      I2C_SMBUS_WORD_DATA,&data);
}

s32 i2c_smbus_process_call(struct i2c_client *client, u8 command, u16 value)
{
	union i2c_smbus_data data;
	data.word = value;
	if (i2c_smbus_xfer(client->adapter,client->addr,client->flags,
	                   I2C_SMBUS_WRITE,command,
	                   I2C_SMBUS_PROC_CALL, &data))
		return -1;
	else
		return 0x0FFFF & data.word;
}

/* Returns the number of read bytes */
s32 i2c_smbus_read_block_data(struct i2c_client *client, u8 command, u8 *values)
{
	union i2c_smbus_data data;
	int i;
	if (i2c_smbus_xfer(client->adapter,client->addr,client->flags,
	                   I2C_SMBUS_READ,command,
	                   I2C_SMBUS_BLOCK_DATA,&data))
		return -1;
	else {
		for (i = 1; i <= data.block[0]; i++)
			values[i-1] = data.block[i];
		return data.block[0];
	}
}

s32 i2c_smbus_write_block_data(struct i2c_client *client, u8 command, u8 length, u8 *values)
{
	union i2c_smbus_data data;
	int i;
	if (length > I2C_SMBUS_BLOCK_MAX)
		length = I2C_SMBUS_BLOCK_MAX;
	for (i = 1; i <= length; i++)
		data.block[i] = values[i-1];
	data.block[0] = length;
	return i2c_smbus_xfer(client->adapter,client->addr,client->flags,
	                      I2C_SMBUS_WRITE,command,
	                      I2C_SMBUS_BLOCK_DATA,&data);
}

/* Returns the number of read bytes */
s32 i2c_smbus_block_process_call(struct i2c_client *client, u8 command, u8 length, u8 *values)
{
	union i2c_smbus_data data;
	int i;
	if (length > I2C_SMBUS_BLOCK_MAX - 1)
		return -1;
	data.block[0] = length;
	for (i = 1; i <= length; i++)
		data.block[i] = values[i-1];
	if(i2c_smbus_xfer(client->adapter,client->addr,client->flags,
	                  I2C_SMBUS_WRITE, command,
	                  I2C_SMBUS_BLOCK_PROC_CALL, &data))
		return -1;
	for (i = 1; i <= data.block[0]; i++)
		values[i-1] = data.block[i];
	return data.block[0];
}

/* Returns the number of read bytes */
s32 i2c_smbus_read_i2c_block_data(struct i2c_client *client, u8 command, u8 *values)
{
	union i2c_smbus_data data;
	int i;
	if (i2c_smbus_xfer(client->adapter,client->addr,client->flags,
	                      I2C_SMBUS_READ,command,
	                      I2C_SMBUS_I2C_BLOCK_DATA,&data))
		return -1;
	else {
		for (i = 1; i <= data.block[0]; i++)
			values[i-1] = data.block[i];
		return data.block[0];
	}
}

s32 i2c_smbus_write_i2c_block_data(struct i2c_client *client, u8 command, u8 length, u8 *values)
{
	union i2c_smbus_data data;
	int i;
	if (length > I2C_SMBUS_I2C_BLOCK_MAX)
		length = I2C_SMBUS_I2C_BLOCK_MAX;
	for (i = 1; i <= length; i++)
		data.block[i] = values[i-1];
	data.block[0] = length;
	return i2c_smbus_xfer(client->adapter,client->addr,client->flags,
	                      I2C_SMBUS_WRITE,command,
	                      I2C_SMBUS_I2C_BLOCK_DATA,&data);
}

/* Simulate a SMBus command using the i2c protocol 
   No checking of parameters is done!  */
static s32 i2c_smbus_xfer_emulated(struct i2c_adapter * adapter, u16 addr, 
                                   unsigned short flags,
                                   char read_write, u8 command, int size, 
                                   union i2c_smbus_data * data)
{
	/* So we need to generate a series of msgs. In the case of writing, we
	  need to use only one message; when reading, we need two. We initialize
	  most things with sane defaults, to keep the code below somewhat
	  simpler. */
	unsigned char msgbuf0[34];
	unsigned char msgbuf1[34];
	int num = read_write == I2C_SMBUS_READ?2:1;
	struct i2c_msg msg[2] = { { addr, flags, 1, msgbuf0 }, 
	                          { addr, flags | I2C_M_RD, 0, msgbuf1 }
	                        };
	int i;

	msgbuf0[0] = command;
	switch(size) {
	case I2C_SMBUS_QUICK:
		msg[0].len = 0;
		/* Special case: The read/write field is used as data */
		msg[0].flags = flags | (read_write==I2C_SMBUS_READ)?I2C_M_RD:0;
		num = 1;
		break;
	case I2C_SMBUS_BYTE:
		if (read_write == I2C_SMBUS_READ) {
			/* Special case: only a read! */
			msg[0].flags = I2C_M_RD | flags;
			num = 1;
		}
		break;
	case I2C_SMBUS_BYTE_DATA:
		if (read_write == I2C_SMBUS_READ)
			msg[1].len = 1;
		else {
			msg[0].len = 2;
			msgbuf0[1] = data->byte;
		}
		break;
	case I2C_SMBUS_WORD_DATA:
		if (read_write == I2C_SMBUS_READ)
			msg[1].len = 2;
		else {
			msg[0].len=3;
			msgbuf0[1] = data->word & 0xff;
			msgbuf0[2] = (data->word >> 8) & 0xff;
		}
		break;
	case I2C_SMBUS_PROC_CALL:
		num = 2; /* Special case */
		read_write = I2C_SMBUS_READ;
		msg[0].len = 3;
		msg[1].len = 2;
		msgbuf0[1] = data->word & 0xff;
		msgbuf0[2] = (data->word >> 8) & 0xff;
		break;
	case I2C_SMBUS_BLOCK_DATA:
	case I2C_SMBUS_BLOCK_DATA_PEC:
		if (read_write == I2C_SMBUS_READ) {
			dev_err(&adapter->dev, "Block read not supported "
			       "under I2C emulation!\n");
			return -1;
		} else {
			msg[0].len = data->block[0] + 2;
			if (msg[0].len > I2C_SMBUS_BLOCK_MAX + 2) {
				dev_err(&adapter->dev, "smbus_access called with "
				       "invalid block write size (%d)\n",
				       data->block[0]);
				return -1;
			}
			if(size == I2C_SMBUS_BLOCK_DATA_PEC)
				(msg[0].len)++;
			for (i = 1; i <= msg[0].len; i++)
				msgbuf0[i] = data->block[i-1];
		}
		break;
	case I2C_SMBUS_BLOCK_PROC_CALL:
	case I2C_SMBUS_BLOCK_PROC_CALL_PEC:
		dev_dbg(&adapter->dev, "Block process call not supported "
		       "under I2C emulation!\n");
		return -1;
	case I2C_SMBUS_I2C_BLOCK_DATA:
		if (read_write == I2C_SMBUS_READ) {
			msg[1].len = I2C_SMBUS_I2C_BLOCK_MAX;
		} else {
			msg[0].len = data->block[0] + 1;
			if (msg[0].len > I2C_SMBUS_I2C_BLOCK_MAX + 1) {
				dev_err(&adapter->dev, "i2c_smbus_xfer_emulated called with "
				       "invalid block write size (%d)\n",
				       data->block[0]);
				return -1;
			}
			for (i = 1; i <= data->block[0]; i++)
				msgbuf0[i] = data->block[i];
		}
		break;
	default:
		dev_err(&adapter->dev, "smbus_access called with invalid size (%d)\n",
		       size);
		return -1;
	}

	if (i2c_transfer(adapter, msg, num) < 0)
		return -1;

	if (read_write == I2C_SMBUS_READ)
		switch(size) {
			case I2C_SMBUS_BYTE:
				data->byte = msgbuf0[0];
				break;
			case I2C_SMBUS_BYTE_DATA:
				data->byte = msgbuf1[0];
				break;
			case I2C_SMBUS_WORD_DATA: 
			case I2C_SMBUS_PROC_CALL:
				data->word = msgbuf1[0] | (msgbuf1[1] << 8);
				break;
			case I2C_SMBUS_I2C_BLOCK_DATA:
				/* fixed at 32 for now */
				data->block[0] = I2C_SMBUS_I2C_BLOCK_MAX;
				for (i = 0; i < I2C_SMBUS_I2C_BLOCK_MAX; i++)
					data->block[i+1] = msgbuf1[i];
				break;
		}
	return 0;
}


s32 i2c_smbus_xfer(struct i2c_adapter * adapter, u16 addr, unsigned short flags,
                   char read_write, u8 command, int size, 
                   union i2c_smbus_data * data)
{
	s32 res;
	int swpec = 0;
	u8 partial = 0;

	flags &= I2C_M_TEN | I2C_CLIENT_PEC;
	if((flags & I2C_CLIENT_PEC) &&
	   !(i2c_check_functionality(adapter, I2C_FUNC_SMBUS_HWPEC_CALC))) {
		swpec = 1;
		if(read_write == I2C_SMBUS_READ &&
		   size == I2C_SMBUS_BLOCK_DATA)
			size = I2C_SMBUS_BLOCK_DATA_PEC;
		else if(size == I2C_SMBUS_PROC_CALL)
			size = I2C_SMBUS_PROC_CALL_PEC;
		else if(size == I2C_SMBUS_BLOCK_PROC_CALL) {
			i2c_smbus_add_pec(addr, command,
		                          I2C_SMBUS_BLOCK_DATA, data);
			partial = data->block[data->block[0] + 1];
			size = I2C_SMBUS_BLOCK_PROC_CALL_PEC;
		} else if(read_write == I2C_SMBUS_WRITE &&
		          size != I2C_SMBUS_QUICK &&
		          size != I2C_SMBUS_I2C_BLOCK_DATA)
			size = i2c_smbus_add_pec(addr, command, size, data);
	}

	if (adapter->algo->smbus_xfer) {
		down(&adapter->bus_lock);
		res = adapter->algo->smbus_xfer(adapter,addr,flags,read_write,
		                                command,size,data);
		up(&adapter->bus_lock);
	} else
		res = i2c_smbus_xfer_emulated(adapter,addr,flags,read_write,
	                                      command,size,data);

	if(res >= 0 && swpec &&
	   size != I2C_SMBUS_QUICK && size != I2C_SMBUS_I2C_BLOCK_DATA &&
	   (read_write == I2C_SMBUS_READ || size == I2C_SMBUS_PROC_CALL_PEC ||
	    size == I2C_SMBUS_BLOCK_PROC_CALL_PEC)) {
		if(i2c_smbus_check_pec(addr, command, size, partial, data))
			return -1;
	}
	return res;
}


/* You should always define `functionality'; the 'else' is just for
   backward compatibility. */ 
u32 i2c_get_functionality (struct i2c_adapter *adap)
{
	if (adap->algo->functionality)
		return adap->algo->functionality(adap);
	else
		return 0xffffffff;
}

int i2c_check_functionality (struct i2c_adapter *adap, u32 func)
{
	u32 adap_func = i2c_get_functionality (adap);
	return (func & adap_func) == func;
}

EXPORT_SYMBOL(i2c_add_adapter);
EXPORT_SYMBOL(i2c_del_adapter);
EXPORT_SYMBOL(i2c_add_driver);
EXPORT_SYMBOL(i2c_del_driver);
EXPORT_SYMBOL(i2c_attach_client);
EXPORT_SYMBOL(i2c_detach_client);
EXPORT_SYMBOL(i2c_use_client);
EXPORT_SYMBOL(i2c_release_client);
EXPORT_SYMBOL(i2c_clients_command);
EXPORT_SYMBOL(i2c_check_addr);

EXPORT_SYMBOL(i2c_master_send);
EXPORT_SYMBOL(i2c_master_recv);
EXPORT_SYMBOL(i2c_control);
EXPORT_SYMBOL(i2c_transfer);
EXPORT_SYMBOL(i2c_adapter_id);
EXPORT_SYMBOL(i2c_get_adapter);
EXPORT_SYMBOL(i2c_put_adapter);
EXPORT_SYMBOL(i2c_probe);

EXPORT_SYMBOL(i2c_smbus_xfer);
EXPORT_SYMBOL(i2c_smbus_write_quick);
EXPORT_SYMBOL(i2c_smbus_read_byte);
EXPORT_SYMBOL(i2c_smbus_write_byte);
EXPORT_SYMBOL(i2c_smbus_read_byte_data);
EXPORT_SYMBOL(i2c_smbus_write_byte_data);
EXPORT_SYMBOL(i2c_smbus_read_word_data);
EXPORT_SYMBOL(i2c_smbus_write_word_data);
EXPORT_SYMBOL(i2c_smbus_process_call);
EXPORT_SYMBOL(i2c_smbus_read_block_data);
EXPORT_SYMBOL(i2c_smbus_write_block_data);
EXPORT_SYMBOL(i2c_smbus_read_i2c_block_data);
EXPORT_SYMBOL(i2c_smbus_write_i2c_block_data);

EXPORT_SYMBOL(i2c_get_functionality);
EXPORT_SYMBOL(i2c_check_functionality);

MODULE_AUTHOR("Simon G. Vogl <[e-mail]>");
MODULE_DESCRIPTION("I2C-Bus main module");
MODULE_LICENSE("GPL");