[PATCH linux dev-4.10 v2] drivers: i2c: fsi: Add proper abort method
Christopher Bostic
cbostic at linux.vnet.ibm.com
Sat Oct 21 07:30:09 AEDT 2017
Reviewed-by: Christopher Bostic <cbostic at linux.vnet.ibm.com>
On 10/20/17 3:02 PM, Eddie James wrote:
> From: "Edward A. James" <eajames at us.ibm.com>
>
> Driver wasn't cleaning up on timeout or in an error situation properly.
> Need to do a full reset if we fail in order to re-stablish a good state
> of the engine.
>
> Signed-off-by: Edward A. James <eajames at us.ibm.com>
> ---
>
> Changes since v1:
> * switch to TASK_UNINTERRUPTIBLE for waiting for command complete
>
> drivers/i2c/busses/i2c-fsi.c | 259 +++++++++++++++++++++++++++++++------------
> 1 file changed, 191 insertions(+), 68 deletions(-)
>
> diff --git a/drivers/i2c/busses/i2c-fsi.c b/drivers/i2c/busses/i2c-fsi.c
> index 1af9c01..fa44017 100644
> --- a/drivers/i2c/busses/i2c-fsi.c
> +++ b/drivers/i2c/busses/i2c-fsi.c
> @@ -133,6 +133,11 @@
> #define I2C_ESTAT_SELF_BUSY 0x00000040
> #define I2C_ESTAT_VERSION 0x0000001f
>
> +#define I2C_PORT_BUSY_RESET 0x80000000
> +
> +#define I2C_LOCAL_WAIT_TIMEOUT 2 /* jiffies */
> +#define I2C_ABORT_TIMEOUT msecs_to_jiffies(100)
> +
> struct fsi_i2c_master {
> struct fsi_device *fsi;
> u8 fifo_size;
> @@ -351,22 +356,185 @@ static int fsi_i2c_read_fifo(struct fsi_i2c_port *port, struct i2c_msg *msg,
> return rc;
> }
>
> +static int fsi_i2c_reset_bus(struct fsi_i2c_master *i2c)
> +{
> + int i, rc;
> + u32 mode, dummy = 0;
> +
> + rc = fsi_i2c_read_reg(i2c->fsi, I2C_FSI_MODE, &mode);
> + if (rc)
> + return rc;
> +
> + mode |= I2C_MODE_DIAG;
> + rc = fsi_i2c_write_reg(i2c->fsi, I2C_FSI_MODE, &mode);
> + if (rc)
> + return rc;
> +
> + for (i = 0; i < 9; ++i) {
> + rc = fsi_i2c_write_reg(i2c->fsi, I2C_FSI_RESET_SCL, &dummy);
> + if (rc)
> + return rc;
> +
> + rc = fsi_i2c_write_reg(i2c->fsi, I2C_FSI_SET_SCL, &dummy);
> + if (rc)
> + return rc;
> + }
> +
> + rc = fsi_i2c_write_reg(i2c->fsi, I2C_FSI_RESET_SCL, &dummy);
> + if (rc)
> + return rc;
> +
> + rc = fsi_i2c_write_reg(i2c->fsi, I2C_FSI_RESET_SDA, &dummy);
> + if (rc)
> + return rc;
> +
> + rc = fsi_i2c_write_reg(i2c->fsi, I2C_FSI_SET_SCL, &dummy);
> + if (rc)
> + return rc;
> +
> + rc = fsi_i2c_write_reg(i2c->fsi, I2C_FSI_SET_SDA, &dummy);
> + if (rc)
> + return rc;
> +
> + mode &= ~I2C_MODE_DIAG;
> + rc = fsi_i2c_write_reg(i2c->fsi, I2C_FSI_MODE, &mode);
> +
> + return rc;
> +}
> +
> +static int fsi_i2c_reset(struct fsi_i2c_master *i2c, u16 port)
> +{
> + int rc;
> + u32 mode, stat, dummy = 0;
> +
> + /* reset engine */
> + rc = fsi_i2c_write_reg(i2c->fsi, I2C_FSI_RESET_I2C, &dummy);
> + if (rc)
> + return rc;
> +
> + /* re-init engine */
> + rc = fsi_i2c_dev_init(i2c);
> + if (rc)
> + return rc;
> +
> + rc = fsi_i2c_read_reg(i2c->fsi, I2C_FSI_MODE, &mode);
> + if (rc)
> + return rc;
> +
> + /* set port; default after reset is 0 */
> + if (port) {
> + mode = SETFIELD(I2C_MODE_PORT, mode, port);
> + rc = fsi_i2c_write_reg(i2c->fsi, I2C_FSI_MODE, &mode);
> + if (rc)
> + return rc;
> + }
> +
> + /* reset busy register; hw workaround */
> + dummy = I2C_PORT_BUSY_RESET;
> + rc = fsi_i2c_write_reg(i2c->fsi, I2C_FSI_PORT_BUSY, &dummy);
> + if (rc)
> + return rc;
> +
> + /* force bus reset */
> + rc = fsi_i2c_reset_bus(i2c);
> + if (rc)
> + return rc;
> +
> + /* reset errors */
> + dummy = 0;
> + rc = fsi_i2c_write_reg(i2c->fsi, I2C_FSI_RESET_ERR, &dummy);
> + if (rc)
> + return rc;
> +
> + /* wait for command complete */
> + set_current_state(TASK_UNINTERRUPTIBLE);
> + schedule_timeout(I2C_LOCAL_WAIT_TIMEOUT);
> +
> + rc = fsi_i2c_read_reg(i2c->fsi, I2C_FSI_STAT, &stat);
> + if (rc)
> + return rc;
> +
> + if (stat & I2C_STAT_CMD_COMP)
> + return 0;
> +
> + /* failed to get command complete; reset engine again */
> + rc = fsi_i2c_write_reg(i2c->fsi, I2C_FSI_RESET_I2C, &dummy);
> + if (rc)
> + return rc;
> +
> + /* re-init engine again */
> + rc = fsi_i2c_dev_init(i2c);
> + if (rc)
> + return rc;
> +
> + return 0;
> +}
> +
> +static int fsi_i2c_abort(struct fsi_i2c_port *port, u32 status)
> +{
> + int rc;
> + unsigned long start;
> + u32 cmd = I2C_CMD_WITH_STOP;
> + struct fsi_device *fsi = port->master->fsi;
> +
> + rc = fsi_i2c_reset(port->master, port->port);
> + if (rc)
> + return rc;
> +
> + /* skip final stop command for these errors */
> + if (status & (I2C_STAT_PARITY | I2C_STAT_LOST_ARB | I2C_STAT_STOP_ERR))
> + return 0;
> +
> + rc = fsi_i2c_write_reg(fsi, I2C_FSI_CMD, &cmd);
> + if (rc)
> + return rc;
> +
> + start = jiffies;
> +
> + do {
> + rc = fsi_i2c_read_reg(fsi, I2C_FSI_STAT, &status);
> + if (rc)
> + return rc;
> +
> + if (status & I2C_STAT_CMD_COMP)
> + return 0;
> +
> + set_current_state(TASK_INTERRUPTIBLE);
> + if (schedule_timeout(I2C_LOCAL_WAIT_TIMEOUT) > 0)
> + return -EINTR;
> +
> + } while (time_after(start + I2C_ABORT_TIMEOUT, jiffies));
> +
> + return -ETIME;
> +}
> +
> 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);
> + 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 -EFAULT;
>
> + if (status & I2C_STAT_LOST_ARB)
> + return -ECANCELED;
> +
> + if (status & I2C_STAT_STOP_ERR)
> + return -EBADMSG;
> +
> return -EIO;
> }
>
> @@ -396,9 +564,9 @@ static int fsi_i2c_handle_status(struct fsi_i2c_port *port,
> 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;
> + int rc, rc_abort;
> + unsigned long start = jiffies;
>
> do {
> rc = fsi_i2c_read_reg(port->master->fsi, I2C_FSI_STAT,
> @@ -419,13 +587,21 @@ static int fsi_i2c_wait(struct fsi_i2c_port *port, struct i2c_msg *msg,
> continue;
> }
>
> - set_current_state(TASK_UNINTERRUPTIBLE);
> - schedule_timeout(local_timeout);
> - timeout = (timeout < local_timeout) ? 0 :
> - timeout - local_timeout;
> - } while (timeout);
> + set_current_state(TASK_INTERRUPTIBLE);
> + if (schedule_timeout(I2C_LOCAL_WAIT_TIMEOUT) > 0) {
> + rc = -EINTR;
> + goto abort;
> + }
> + } while (time_after(start + timeout, jiffies));
>
> - return -ETIME;
> + rc = -ETIME;
> +
> +abort:
> + rc_abort = fsi_i2c_abort(port, status);
> + if (rc_abort)
> + return rc_abort;
> +
> + return rc;
> }
>
> static int fsi_i2c_xfer(struct i2c_adapter *adap, struct i2c_msg *msgs,
> @@ -469,72 +645,19 @@ static u32 fsi_i2c_functionality(struct i2c_adapter *adap)
> | I2C_FUNC_SMBUS_EMUL | I2C_FUNC_SMBUS_BLOCK_DATA;
> }
>
> -static int fsi_i2c_low_level_recover_bus(struct fsi_i2c_master *i2c)
> -{
> - int i, rc;
> - u32 mode, dummy = 0;
> -
> - rc = fsi_i2c_read_reg(i2c->fsi, I2C_FSI_MODE, &mode);
> - if (rc)
> - return rc;
> -
> - mode |= I2C_MODE_DIAG;
> - rc = fsi_i2c_write_reg(i2c->fsi, I2C_FSI_MODE, &mode);
> - if (rc)
> - return rc;
> -
> - for (i = 0; i < 9; ++i) {
> - rc = fsi_i2c_write_reg(i2c->fsi, I2C_FSI_RESET_SCL, &dummy);
> - if (rc)
> - return rc;
> -
> - rc = fsi_i2c_write_reg(i2c->fsi, I2C_FSI_SET_SCL, &dummy);
> - if (rc)
> - return rc;
> - }
> -
> - rc = fsi_i2c_write_reg(i2c->fsi, I2C_FSI_RESET_SCL, &dummy);
> - if (rc)
> - return rc;
> -
> - rc = fsi_i2c_write_reg(i2c->fsi, I2C_FSI_RESET_SDA, &dummy);
> - if (rc)
> - return rc;
> -
> - rc = fsi_i2c_write_reg(i2c->fsi, I2C_FSI_SET_SCL, &dummy);
> - if (rc)
> - return rc;
> -
> - rc = fsi_i2c_write_reg(i2c->fsi, I2C_FSI_SET_SDA, &dummy);
> - if (rc)
> - return rc;
> -
> - mode &= ~I2C_MODE_DIAG;
> - rc = fsi_i2c_write_reg(i2c->fsi, I2C_FSI_MODE, &mode);
> -
> - return rc;
> -}
> -
> static int fsi_i2c_recover_bus(struct i2c_adapter *adap)
> {
> int rc;
> - u32 dummy = 0;
> struct fsi_i2c_port *port = adap->algo_data;
> - struct fsi_i2c_master *i2c = port->master;
> + struct fsi_i2c_master *master = port->master;
>
> - rc = fsi_i2c_write_reg(i2c->fsi, I2C_FSI_RESET_I2C, &dummy);
> + rc = fsi_i2c_lock_master(master, adap->timeout);
> if (rc)
> return rc;
>
> - rc = fsi_i2c_dev_init(i2c);
> - if (rc)
> - return rc;
> + rc = fsi_i2c_reset(master, port->port);
>
> - rc = fsi_i2c_low_level_recover_bus(i2c);
> - if (rc)
> - return rc;
> -
> - rc = fsi_i2c_write_reg(i2c->fsi, I2C_FSI_RESET_ERR, &dummy);
> + fsi_i2c_unlock_master(master);
>
> return rc;
> }
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