From: jean-jacques hiblot <jjhiblot@xxxxxxxxx>
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@xxxxxxxxxxxxxxx>
---
drivers/i2c/busses/i2c-ibm_iic.c | 91 ++++++++++++++++++++++++++++++++--------
drivers/i2c/busses/i2c-ibm_iic.h | 1 +
2 files changed, 74 insertions(+), 18 deletions(-)
diff --git a/drivers/i2c/busses/i2c-ibm_iic.c b/drivers/i2c/busses/i2c-ibm_iic.c
index 857259e..aefe228 100644
--- a/drivers/i2c/busses/i2c-ibm_iic.c
+++ b/drivers/i2c/busses/i2c-ibm_iic.c
@@ -336,11 +336,45 @@ 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 */
+ 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)
+ */
+ 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");
@@ -348,8 +382,17 @@ 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");
@@ -381,7 +424,8 @@ 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;
}
@@ -400,7 +444,8 @@ 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;
}
@@ -428,7 +473,8 @@ 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++;
@@ -625,24 +671,29 @@ 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) {
@@ -709,6 +760,8 @@ 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;
@@ -729,6 +782,8 @@ 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;
};
--
1.8.4.2
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