On 22/11/2013 09:58, jean-jacques hiblot wrote:
> When no valid interrupt is defined for the controller, use polling to handle
> the transfers.
> The polling mode can also be forced with the "iic_force_poll" module parameter.
>
> Signed-off-by: jean-jacques hiblot <jjhiblot@xxxxxxxxx>
> ---
> drivers/i2c/busses/i2c-ibm_iic.c | 89 ++++++++++++++++++++++++++++++++--------
> drivers/i2c/busses/i2c-ibm_iic.h | 1 +
> 2 files changed, 73 insertions(+), 17 deletions(-)
>
> diff --git a/drivers/i2c/busses/i2c-ibm_iic.c b/drivers/i2c/busses/i2c-ibm_iic.c
> index a3f3f1b..1dde6e1 100644
> --- a/drivers/i2c/busses/i2c-ibm_iic.c
> +++ b/drivers/i2c/busses/i2c-ibm_iic.c
> @@ -334,11 +334,45 @@ static irqreturn_t iic_handler(int irq, void *dev_id)
> }
>
> /*
> + * Polling used when interrupt can't be used
> + */
> +static int poll_for_end_of_transfer(struct ibm_iic_private *dev, u32 timeout)
> +{
> + struct iic_regs __iomem *iic = dev->vaddr;
> + u32 status;
> + unsigned long end = jiffies + timeout;
> +
> + while ((dev->transfer_complete == 0) &&
> + time_after(end, jiffies) &&
> + !signal_pending(current)) {
> + status = in_8(&iic->sts);
> + /* check if the transfer is done or an error occured */
occurred
> + if ((status & (STS_ERR | STS_SCMP)) || !(status & STS_PT))
> + iic_xfer_bytes(dev);
> + /* The transfer is not complete,
> + * calling schedule relaxes the CPU load and allows to know
> + * if the process is being signaled (for abortion)
> + */
nitpick: wrong muliline comment style
> + if (dev->transfer_complete == 0)
> + schedule();
> + }
> +
> + if (signal_pending(current))
> + return -ERESTARTSYS;
> +
> + if (dev->transfer_complete == 0)
> + return 0;
> +
> + return 1;
> +}
> +
> +/*
> * Try to abort active transfer.
> */
> static void iic_abort_xfer(struct ibm_iic_private *dev)
> {
> struct device *device = dev->adap.dev.parent;
> + struct iic_regs __iomem *iic = dev->vaddr;
> unsigned long end;
>
> DBG(dev, "aborting transfer\n");
> @@ -346,8 +380,17 @@ static void iic_abort_xfer(struct ibm_iic_private *dev)
> end = jiffies + 10;
> dev->abort = 1;
>
> - while (time_after(end, jiffies) && !dev->transfer_complete)
> - schedule();
> + while (time_after(end, jiffies) && !dev->transfer_complete) {
> + u32 sts;
> + if (dev->use_polling) {
> + sts = in_8(&iic->sts);
> + /* check if the transfer is done or an error occured */
> + if ((sts & (STS_ERR | STS_SCMP)) || !(sts & STS_PT))
> + iic_xfer_bytes(dev);
> + }
> + if (dev->transfer_complete == 0)
> + schedule();
> + }
>
> if (!dev->transfer_complete) {
> dev_err(device, "abort operation failed\n");
> @@ -379,7 +422,8 @@ static int iic_xfer_bytes(struct ibm_iic_private *dev)
> if (dev->status == -ECANCELED) {
> DBG(dev, "abort completed\n");
> dev->transfer_complete = 1;
> - complete(&dev->iic_compl);
> + if (!dev->use_polling)
> + complete(&dev->iic_compl);
> return dev->status;
> }
>
> @@ -398,7 +442,8 @@ static int iic_xfer_bytes(struct ibm_iic_private *dev)
>
> dev->status = -EIO;
> dev->transfer_complete = 1;
> - complete(&dev->iic_compl);
> + if (!dev->use_polling)
> + complete(&dev->iic_compl);
> return dev->status;
> }
>
> @@ -426,7 +471,8 @@ static int iic_xfer_bytes(struct ibm_iic_private *dev)
> if (dev->current_msg == dev->num_msgs) {
> DBG2(dev, "end of transfer\n");
> dev->transfer_complete = 1;
> - complete(&dev->iic_compl);
> + if (!dev->use_polling)
> + complete(&dev->iic_compl);
> return dev->status;
> }
> pm++;
> @@ -617,23 +663,28 @@ static int iic_xfer(struct i2c_adapter *adap, struct i2c_msg *msgs, int num)
> /* Load slave address */
> iic_address(dev, &msgs[0]);
>
> - init_completion(&dev->iic_compl);
> + if (!dev->use_polling)
> + init_completion(&dev->iic_compl);
>
> /* start the transfer */
> ret = iic_xfer_bytes(dev);
>
> if (ret == 0) {
> - /* enable the interrupts */
> - out_8(&iic->mdcntl, MDCNTL_EINT);
> - /* unmask the interrupts */
> - out_8(&iic->intmsk, INTRMSK_EIMTC | INTRMSK_EITA |
> - INTRMSK_EIIC | INTRMSK_EIHE);
> - /* wait for the transfer to complete */
> - ret = wait_for_completion_interruptible_timeout(
> - &dev->iic_compl, num * HZ);
> - /* we don't mask the interrupts here because we may
> - * need them to abort the transfer gracefully
> - */
> + if (dev->use_polling) {
> + ret = poll_for_end_of_transfer(dev, num * HZ);
> + } else {
> + /* enable the interrupts */
> + out_8(&iic->mdcntl, MDCNTL_EINT);
> + /* unmask the interrupts */
> + out_8(&iic->intmsk, INTRMSK_EIMTC | INTRMSK_EITA |
> + INTRMSK_EIIC | INTRMSK_EIHE);
> + /* wait for the transfer to complete */
> + ret = wait_for_completion_interruptible_timeout(
> + &dev->iic_compl, num * HZ);
> + /* we don't mask the interrupts here because we may
> + * need them to abort the transfer gracefully
> + */
> + }
> }
>
> if (ret == 0) {
> @@ -699,6 +750,8 @@ static int iic_request_irq(struct platform_device *ofdev,
> struct device_node *np = ofdev->dev.of_node;
> int irq;
>
> + dev->use_polling = 1;
> +
> if (iic_force_poll)
> return 0;
>
> @@ -718,6 +771,8 @@ static int iic_request_irq(struct platform_device *ofdev,
> return 0;
> }
>
> + dev->use_polling = 0;
> +
> return irq;
> }
>
> diff --git a/drivers/i2c/busses/i2c-ibm_iic.h b/drivers/i2c/busses/i2c-ibm_iic.h
> index 0ee28a9..523cfc1 100644
> --- a/drivers/i2c/busses/i2c-ibm_iic.h
> +++ b/drivers/i2c/busses/i2c-ibm_iic.h
> @@ -58,6 +58,7 @@ struct ibm_iic_private {
> int transfer_complete;
> int status;
> int abort;
> + int use_polling;
> struct completion iic_compl;
> };
>
>
--
Gregory Clement, Free Electrons
Kernel, drivers, real-time and embedded Linux
development, consulting, training and support.
http://free-electrons.com
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