bus: mhi: core: Allow shared IRQ for event rings

There is no requirement for using a dedicated IRQ per event ring.
Some systems does not support multiple MSI vectors (e.g. intel
without CONFIG_IRQ_REMAP), In that case the MHI controller can
configure all the event rings to use the same interrupt (as fallback).

Allow this by removing the nr_irqs = ev_ring test and add extra check
in the irq_setup function.
Reviewed-by: Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>
Signed-off-by: Loic Poulain <loic.poulain@linaro.org>
Signed-off-by: Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>
Link: https://lore.kernel.org/r/20200929175218.8178-17-manivannan.sadhasivam@linaro.orgSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/bus/mhi/core/init.c

@@ -162,6 +162,13 @@ int mhi_init_irq_setup(struct mhi_controller *mhi_cntrl)
 		if (mhi_event->offload_ev)
 			continue;
 
+		if (mhi_event->irq >= mhi_cntrl->nr_irqs) {
+			dev_err(dev, "irq %d not available for event ring\n",
+				mhi_event->irq);
+			ret = -EINVAL;
+			goto error_request;
+		}
+
 		ret = request_irq(mhi_cntrl->irq[mhi_event->irq],
 				  mhi_irq_handler,
 				  IRQF_SHARED | IRQF_NO_SUSPEND,

drivers/bus/mhi/core/pm.c

@@ -918,7 +918,7 @@ int mhi_async_power_up(struct mhi_controller *mhi_cntrl)
 
 	dev_info(dev, "Requested to power ON\n");
 
-	if (mhi_cntrl->nr_irqs < mhi_cntrl->total_ev_rings)
+	if (mhi_cntrl->nr_irqs < 1)
 		return -EINVAL;
 
 	/* Supply default wake routines if not provided by controller driver */