[PATCH linux dev-4.10 v2 3/6] drivers: i2c: Add transfer implementation for FSI algorithm
Joel Stanley
joel at jms.id.au
Thu Jun 1 16:11:59 AEST 2017
On Thu, May 11, 2017 at 1:22 AM, Eddie James <eajames at linux.vnet.ibm.com> wrote:
> From: "Edward A. James" <eajames at us.ibm.com>
>
> 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: Edward A. James <eajames at us.ibm.com>
> ---
> drivers/i2c/busses/i2c-fsi.c | 193 ++++++++++++++++++++++++++++++++++++++++++-
> 1 file changed, 191 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/i2c/busses/i2c-fsi.c b/drivers/i2c/busses/i2c-fsi.c
> index cdebc99..f690b16 100644
> --- a/drivers/i2c/busses/i2c-fsi.c
> +++ b/drivers/i2c/busses/i2c-fsi.c
> @@ -143,6 +143,7 @@ struct fsi_i2c_port {
> struct i2c_adapter adapter;
> struct fsi_i2c_master *master;
> u16 port;
> + u16 xfrd;
> };
>
> static DEFINE_IDA(fsi_i2c_ida);
> @@ -229,17 +230,205 @@ static int fsi_i2c_set_port(struct fsi_i2c_port *port)
> return rc;
> }
>
> +static int fsi_i2c_start(struct fsi_i2c_port *port, struct i2c_msg *msg,
> + bool stop)
> +{
> + int rc;
> + 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 = SETFIELD(I2C_CMD_ADDR, cmd, msg->addr >> 1);
> + cmd = SETFIELD(I2C_CMD_LEN, cmd, msg->len);
> +
> + rc = fsi_i2c_write_reg(i2c->fsi, I2C_FSI_CMD, &cmd);
> +
> + return rc;
> +}
> +
> +static int fsi_i2c_write_fifo(struct fsi_i2c_port *port, struct i2c_msg *msg,
> + u8 fifo_count)
> +{
> + int write;
> + int rc = 0;
> + struct fsi_i2c_master *i2c = port->master;
> + int bytes_to_write = i2c->fifo_size - fifo_count;
> + int bytes_remaining = msg->len - port->xfrd;
> +
> + if (bytes_to_write > bytes_remaining)
> + bytes_to_write = bytes_remaining;
> +
> + while (bytes_to_write > 0) {
> + write = bytes_to_write;
> + /* fsi limited to max 4 byte aligned ops */
> + if (bytes_to_write > 4)
> + write = 4;
> + else if (write == 3)
> + write = 2;
> +
> + 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 rc;
> +}
> +
> +static int fsi_i2c_read_fifo(struct fsi_i2c_port *port, struct i2c_msg *msg,
> + u8 fifo_count)
> +{
> + int read;
> + int rc = 0;
> + struct fsi_i2c_master *i2c = port->master;
> + int xfr_remaining = msg->len - port->xfrd;
> + u32 dummy;
> +
> + while (fifo_count) {
> + read = fifo_count;
> + /* fsi limited to max 4 byte aligned ops */
> + if (fifo_count > 4)
> + read = 4;
> + else if (read == 3)
> + read = 2;
> +
> + if (xfr_remaining) {
> + if (xfr_remaining < read)
> + read = 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;
> + }
> +
> + fifo_count -= read;
> + }
> +
> + return rc;
> +}
> +
> +static int fsi_i2c_handle_status(struct fsi_i2c_port *port,
> + struct i2c_msg *msg, u32 status)
> +{
> + int rc;
> + u8 fifo_count;
> + struct fsi_i2c_master *i2c = port->master;
> + u32 dummy = 0;
> +
> + if (status & I2C_STAT_ERR) {
> + rc = fsi_i2c_write_reg(i2c->fsi, I2C_FSI_RESET_ERR, &dummy);
> + if (rc)
> + return rc;
> +
> + if (status & I2C_STAT_NACK)
> + return -EFAULT;
Why EFAULT?
> +
> + return -EIO;
> + }
> +
> + if (status & I2C_STAT_DAT_REQ) {
> + fifo_count = GETFIELD(I2C_STAT_FIFO_COUNT, status);
> +
> + if (msg->flags & I2C_M_RD)
> + rc = fsi_i2c_read_fifo(port, msg, fifo_count);
> + else
> + rc = fsi_i2c_write_fifo(port, msg, fifo_count);
> +
> + return rc;
> + }
> +
> + if (status & I2C_STAT_CMD_COMP) {
> + if (port->xfrd < msg->len)
> + rc = -ENODATA;
> + else
> + rc = msg->len;
> + }
> +
> + return rc;
rc is returned uninitialised here when all of the if () tests are false.
> +}
> +
> +static int fsi_i2c_wait(struct fsi_i2c_port *port, struct i2c_msg *msg,
> + unsigned long timeout)
> +{
> + const unsigned long local_timeout = 2; /* jiffies */
> + u32 status = 0;
> + int rc;
> +
> + 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;
> + }
> +
> + set_current_state(TASK_UNINTERRUPTIBLE);
> + schedule_timeout(local_timeout);
This is an open coded msleep(2). Just use msleep.
> + timeout = (timeout < local_timeout) ? 0 :
> + timeout - local_timeout;
And then this could be (untested):
end = timeout + jiffies;
do {
} while (time_is_before_jiffies(end));
> + } while (timeout);
> +
> + return -ETIME;
> +}
> +
> 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 -ENOSYS;
> + 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;
> }
>
> static u32 fsi_i2c_functionality(struct i2c_adapter *adap)
> --
> 1.8.3.1
>
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