[v8,5/7] i2c: fsi: Add transfer implementation

Message ID 1527714464-8642-6-git-send-email-eajames@linux.vnet.ibm.com
State Superseded
Headers show
Series
  • i2c: Add FSI-attached I2C master algorithm
Related show

Commit Message

Eddie James May 30, 2018, 9:07 p.m.
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 | 196 ++++++++++++++++++++++++++++++++++++++++++-
 1 file changed, 194 insertions(+), 2 deletions(-)

Comments

Andy Shevchenko May 31, 2018, 6:50 a.m. | #1
On Thu, May 31, 2018 at 12:07 AM, Eddie James
<eajames@linux.vnet.ibm.com> wrote:
> Execute I2C transfers from the FSI-attached I2C master. Use polling
> instead of interrupts as we have no hardware IRQ over FSI.
>

Few nitpicks, after addressing them (field definition is up to you though)

Reviewed-by: Andy Shevchenko <andy.shevchenko@gmail.com>


> Signed-off-by: Eddie James <eajames@linux.vnet.ibm.com>
> ---
>  drivers/i2c/busses/i2c-fsi.c | 196 ++++++++++++++++++++++++++++++++++++++++++-
>  1 file changed, 194 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/i2c/busses/i2c-fsi.c b/drivers/i2c/busses/i2c-fsi.c
> index e5dd0f7..f24e4b9 100644
> --- a/drivers/i2c/busses/i2c-fsi.c
> +++ b/drivers/i2c/busses/i2c-fsi.c
> @@ -149,6 +149,7 @@ 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,
> @@ -224,6 +225,100 @@ 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;

(1)

> +
> +       if (stop || msg->flags & I2C_M_STOP)
> +               cmd |= I2C_CMD_WITH_STOP;
> +

> +       cmd |= FIELD_PREP(I2C_CMD_ADDR, msg->addr >> 1);

(1) + this looks like:

 // #define I2C_CMD_ADDR           GENMASK(23, 17)
 // #define I2C_CMD_READ           BIT(16)

#define I2C_CMD_8BIT_ADDR           GENMASK(23, 16)
// or even drop I2C_CMD_READ completely

   cmd |= FIELD_PREP(I2C_CMD_8BIT_ADDR, i2c_8bit_addr_from_msg(msg));

> +       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;
> +       else
> +               return op_bytes;

If you have pattern like

if {
 ...
 return;
} else {
 ...
}

'else' is redundant.

> +}

Overall, I think rounddown_pow_of_two() makes sense here.
Though it's your choice.

> +
> +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;
> @@ -387,17 +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);

> +               else
> +                       return fsi_i2c_write_fifo(port, msg, fifo_count);

Redundant 'else'

> +       }
> +
> +       if (status & I2C_STAT_CMD_COMP) {
> +               if (port->xfrd < msg->len)
> +                       return -ENODATA;

> +               else
> +                       return msg->len;

Ditto.

> +       }
> +
> +       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) {

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
>

Patch

diff --git a/drivers/i2c/busses/i2c-fsi.c b/drivers/i2c/busses/i2c-fsi.c
index e5dd0f7..f24e4b9 100644
--- a/drivers/i2c/busses/i2c-fsi.c
+++ b/drivers/i2c/busses/i2c-fsi.c
@@ -149,6 +149,7 @@  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,
@@ -224,6 +225,100 @@  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;
+	else
+		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;
@@ -387,17 +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);
+		else
+			return fsi_i2c_write_fifo(port, msg, fifo_count);
+	}
+
+	if (status & I2C_STAT_CMD_COMP) {
+		if (port->xfrd < msg->len)
+			return -ENODATA;
+		else
+			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;
 }
 
 static u32 fsi_i2c_functionality(struct i2c_adapter *adap)