Re: [PATCH v9 5/7] i2c: fsi: Add transfer implementation

[Eddie James <eajames@linux.vnet.ibm.com>]

On 06/04/2018 02:45 PM, Peter Rosin wrote:
> On 2018-06-04 21:00, Eddie James wrote:
>> Execute I2C transfers from the FSI-attached I2C master. Use polling
>> instead of interrupts as we have no hardware IRQ over FSI.
>>
>> Signed-off-by: Eddie James <eajames@linux.vnet.ibm.com>
>> ---
>>   drivers/i2c/busses/i2c-fsi.c | 195 ++++++++++++++++++++++++++++++++++++++++++-
>>   1 file changed, 193 insertions(+), 2 deletions(-)
>>
>> diff --git a/drivers/i2c/busses/i2c-fsi.c b/drivers/i2c/busses/i2c-fsi.c
>> index 101b9c5..4e5964e 100644
>> --- a/drivers/i2c/busses/i2c-fsi.c
>> +++ b/drivers/i2c/busses/i2c-fsi.c
>> @@ -150,6 +150,7 @@ struct fsi_i2c_port {
>>   	struct i2c_adapter	adapter;
>>   	struct fsi_i2c_master	*master;
>>   	u16			port;
>> +	u16			xfrd;
>>   };
>>   
>>   static int fsi_i2c_read_reg(struct fsi_device *fsi, unsigned int reg,
>> @@ -225,6 +226,99 @@ static int fsi_i2c_set_port(struct fsi_i2c_port *port)
>>   	return fsi_i2c_write_reg(fsi, I2C_FSI_RESET_ERR, &dummy);
>>   }
>>   
>> +static int fsi_i2c_start(struct fsi_i2c_port *port, struct i2c_msg *msg,
>> +			 bool stop)
>> +{
>> +	struct fsi_i2c_master *i2c = port->master;
>> +	u32 cmd = I2C_CMD_WITH_START | I2C_CMD_WITH_ADDR;
>> +
>> +	port->xfrd = 0;
>> +
>> +	if (msg->flags & I2C_M_RD)
>> +		cmd |= I2C_CMD_READ;
>> +
>> +	if (stop || msg->flags & I2C_M_STOP)
>> +		cmd |= I2C_CMD_WITH_STOP;
>> +
>> +	cmd |= FIELD_PREP(I2C_CMD_ADDR, msg->addr >> 1);
>> +	cmd |= FIELD_PREP(I2C_CMD_LEN, msg->len);
>> +
>> +	return fsi_i2c_write_reg(i2c->fsi, I2C_FSI_CMD, &cmd);
>> +}
>> +
>> +static int fsi_i2c_get_op_bytes(int op_bytes)
>> +{
>> +	/* fsi is limited to max 4 byte aligned ops */
>> +	if (op_bytes > 4)
>> +		return 4;
>> +	else if (op_bytes == 3)
>> +		return 2;
>> +	return op_bytes;
>> +}
>> +
>> +static int fsi_i2c_write_fifo(struct fsi_i2c_port *port, struct i2c_msg *msg,
>> +			      u8 fifo_count)
>> +{
>> +	int write;
>> +	int rc;
>> +	struct fsi_i2c_master *i2c = port->master;
>> +	int bytes_to_write = i2c->fifo_size - fifo_count;
>> +	int bytes_remaining = msg->len - port->xfrd;
>> +
>> +	bytes_to_write = min(bytes_to_write, bytes_remaining);
>> +
>> +	while (bytes_to_write) {
>> +		write = fsi_i2c_get_op_bytes(bytes_to_write);
>> +
>> +		rc = fsi_device_write(i2c->fsi, I2C_FSI_FIFO,
>> +				      &msg->buf[port->xfrd], write);
>> +		if (rc)
>> +			return rc;
>> +
>> +		port->xfrd += write;
>> +		bytes_to_write -= write;
>> +	}
>> +
>> +	return 0;
>> +}
>> +
>> +static int fsi_i2c_read_fifo(struct fsi_i2c_port *port, struct i2c_msg *msg,
>> +			     u8 fifo_count)
>> +{
>> +	int read;
>> +	int rc;
>> +	struct fsi_i2c_master *i2c = port->master;
>> +	int bytes_to_read;
>> +	int xfr_remaining = msg->len - port->xfrd;
>> +	u32 dummy;
>> +
>> +	bytes_to_read = min_t(int, fifo_count, xfr_remaining);
>> +
>> +	while (bytes_to_read) {
>> +		read = fsi_i2c_get_op_bytes(bytes_to_read);
>> +
>> +		if (xfr_remaining) {
>> +			rc = fsi_device_read(i2c->fsi, I2C_FSI_FIFO,
>> +					     &msg->buf[port->xfrd], read);
>> +			if (rc)
>> +				return rc;
>> +
>> +			port->xfrd += read;
>> +			xfr_remaining -= read;
>> +		} else {
>> +			/* no more buffer but data in fifo, need to clear it */
>> +			rc = fsi_device_read(i2c->fsi, I2C_FSI_FIFO, &dummy,
>> +					     read);
>> +			if (rc)
>> +				return rc;
>> +		}
>> +
>> +		bytes_to_read -= read;
>> +	}
>> +
>> +	return 0;
>> +}
>> +
>>   static int fsi_i2c_reset_bus(struct fsi_i2c_master *i2c)
>>   {
>>   	int i, rc;
>> @@ -388,17 +482,114 @@ static int fsi_i2c_abort(struct fsi_i2c_port *port, u32 status)
>>   	return -ETIMEDOUT;
>>   }
>>   
>> +static int fsi_i2c_handle_status(struct fsi_i2c_port *port,
>> +				 struct i2c_msg *msg, u32 status)
>> +{
>> +	int rc;
>> +	u8 fifo_count;
>> +
>> +	if (status & I2C_STAT_ERR) {
>> +		rc = fsi_i2c_abort(port, status);
>> +		if (rc)
>> +			return rc;
>> +
>> +		if (status & I2C_STAT_INV_CMD)
>> +			return -EINVAL;
>> +
>> +		if (status & (I2C_STAT_PARITY | I2C_STAT_BE_OVERRUN |
>> +		    I2C_STAT_BE_ACCESS))
>> +			return -EPROTO;
>> +
>> +		if (status & I2C_STAT_NACK)
>> +			return -ENXIO;
>> +
>> +		if (status & I2C_STAT_LOST_ARB)
>> +			return -EAGAIN;
>> +
>> +		if (status & I2C_STAT_STOP_ERR)
>> +			return -EBADMSG;
>> +
>> +		return -EIO;
>> +	}
>> +
>> +	if (status & I2C_STAT_DAT_REQ) {
>> +		fifo_count = FIELD_GET(I2C_STAT_FIFO_COUNT, status);
>> +
>> +		if (msg->flags & I2C_M_RD)
>> +			return fsi_i2c_read_fifo(port, msg, fifo_count);
>> +
>> +		return fsi_i2c_write_fifo(port, msg, fifo_count);
>> +	}
>> +
>> +	if (status & I2C_STAT_CMD_COMP) {
>> +		if (port->xfrd < msg->len)
>> +			return -ENODATA;
>> +
>> +		return msg->len;
>> +	}
>> +
>> +	return 0;
>> +}
>> +
>> +static int fsi_i2c_wait(struct fsi_i2c_port *port, struct i2c_msg *msg,
>> +			unsigned long timeout)
>> +{
>> +	u32 status = 0;
>> +	int rc;
>> +	unsigned long start = jiffies;
>> +
>> +	do {
>> +		rc = fsi_i2c_read_reg(port->master->fsi, I2C_FSI_STAT,
>> +				      &status);
>> +		if (rc)
>> +			return rc;
>> +
>> +		if (status & I2C_STAT_ANY_RESP) {
>> +			rc = fsi_i2c_handle_status(port, msg, status);
>> +			if (rc < 0)
>> +				return rc;
>> +
>> +			/* cmd complete and all data xfrd */
>> +			if (rc == msg->len)
>> +				return 0;
>> +
>> +			/* need to xfr more data, but maybe don't need wait */
>> +			continue;
>> +		}
>> +
>> +		usleep_range(I2C_CMD_SLEEP_MIN_US, I2C_CMD_SLEEP_MAX_US);
>> +	} while (time_after(start + timeout, jiffies));
>> +
>> +	return -ETIMEDOUT;
>> +}
>> +
>>   static int fsi_i2c_xfer(struct i2c_adapter *adap, struct i2c_msg *msgs,
>>   			int num)
>>   {
>> -	int rc;
>> +	int i, rc;
>> +	unsigned long start_time;
>>   	struct fsi_i2c_port *port = adap->algo_data;
>> +	struct i2c_msg *msg;
>>   
>>   	rc = fsi_i2c_set_port(port);
>>   	if (rc)
>>   		return rc;
>>   
>> -	return -EOPNOTSUPP;
>> +	for (i = 0; i < num; i++) {
>> +		msg = msgs + i;
>> +		start_time = jiffies;
>> +
>> +		rc = fsi_i2c_start(port, msg, i == num - 1);
>> +		if (rc)
>> +			return rc;
>> +
>> +		rc = fsi_i2c_wait(port, msg,
>> +				  adap->timeout - (jiffies - start_time));
>> +		if (rc)
>> +			return rc;
>> +	}
>> +
>> +	return 0;
> Zero is not the return value of success for .master_xfer
>
> Hint, "num" is your friend...
>
> Cheers,
> Peter

Good catch, I'll fix that.

Thanks,
Eddie

>
>>   }
>>   
>>   static u32 fsi_i2c_functionality(struct i2c_adapter *adap)
>>