Commit da995d53 authored by Niklas Schnelle's avatar Niklas Schnelle Committed by Vasily Gorbik
Browse files

s390/pci: implement reset_slot for hotplug slot 



This is done by adding a zpci_hot_reset_device() call which does a low
level reset of the PCI function without changing its higher level
function state. This way it can be used while the zPCI function is bound
to a driver and with DMA tables being controlled either through the
IOMMU or DMA APIs which is prohibited when using zpci_disable_device()
as that drop existing DMA translations.

As this reset, unlike a normal FLR, also calls zpci_clear_irq() we need
to implement arch_restore_msi_irqs() and make sure we re-enable IRQs for
the PCI function if they were previously disabled.

Reviewed-by: default avatarPierre Morel <pmorel@linux.ibm.com>
Reviewed-by: default avatarMatthew Rosato <mjrosato@linux.ibm.com>
Signed-off-by: default avatarNiklas Schnelle <schnelle@linux.ibm.com>
Signed-off-by: default avatarVasily Gorbik <gor@linux.ibm.com>
parent 4fe20497

arch/s390/include/asm/pci.h

+1 −0
Original line number Diff line number Diff line
@@ -210,6 +210,7 @@ int zpci_deconfigure_device(struct zpci_dev *zdev); 
void zpci_device_reserved(struct zpci_dev *zdev);

bool zpci_is_device_configured(struct zpci_dev *zdev);



int zpci_hot_reset_device(struct zpci_dev *zdev);

int zpci_register_ioat(struct zpci_dev *, u8, u64, u64, u64);

int zpci_unregister_ioat(struct zpci_dev *, u8);

void zpci_remove_reserved_devices(void);

arch/s390/pci/pci.c

+59 −0
Original line number Diff line number Diff line
@@ -723,6 +723,65 @@ int zpci_disable_device(struct zpci_dev *zdev) 
	return rc;

}



/**

 * zpci_hot_reset_device - perform a reset of the given zPCI function

 * @zdev: the slot which should be reset

 *

 * Performs a low level reset of the zPCI function. The reset is low level in

 * the sense that the zPCI function can be reset without detaching it from the

 * common PCI subsystem. The reset may be performed while under control of

 * either DMA or IOMMU APIs in which case the existing DMA/IOMMU translation

 * table is reinstated at the end of the reset.

 *

 * After the reset the functions internal state is reset to an initial state

 * equivalent to its state during boot when first probing a driver.

 * Consequently after reset the PCI function requires re-initialization via the

 * common PCI code including re-enabling IRQs via pci_alloc_irq_vectors()

 * and enabling the function via e.g.pci_enablde_device_flags().The caller

 * must guard against concurrent reset attempts.

 *

 * In most cases this function should not be called directly but through

 * pci_reset_function() or pci_reset_bus() which handle the save/restore and

 * locking.

 *

 * Return: 0 on success and an error value otherwise

 */

int zpci_hot_reset_device(struct zpci_dev *zdev)

{

	int rc;



	zpci_dbg(3, "rst fid:%x, fh:%x\n", zdev->fid, zdev->fh);

	if (zdev_enabled(zdev)) {

		/* Disables device access, DMAs and IRQs (reset state) */

		rc = zpci_disable_device(zdev);

		/*

		 * Due to a z/VM vs LPAR inconsistency in the error state the

		 * FH may indicate an enabled device but disable says the

		 * device is already disabled don't treat it as an error here.

		 */

		if (rc == -EINVAL)

			rc = 0;

		if (rc)

			return rc;

	}



	rc = zpci_enable_device(zdev);

	if (rc)

		return rc;



	if (zdev->dma_table)

		rc = zpci_register_ioat(zdev, 0, zdev->start_dma, zdev->end_dma,

					(u64)zdev->dma_table);

	else

		rc = zpci_dma_init_device(zdev);

	if (rc) {

		zpci_disable_device(zdev);

		return rc;

	}



	return 0;

}



/**

 * zpci_create_device() - Create a new zpci_dev and add it to the zbus

 * @fid: Function ID of the device to be created

arch/s390/pci/pci_irq.c

+9 −0
Original line number Diff line number Diff line
@@ -387,6 +387,15 @@ void arch_teardown_msi_irqs(struct pci_dev *pdev) 
		airq_iv_free(zpci_ibv[0], zdev->msi_first_bit, zdev->msi_nr_irqs);

}



void arch_restore_msi_irqs(struct pci_dev *pdev)

{

	struct zpci_dev *zdev = to_zpci(pdev);



	if (!zdev->irqs_registered)

		zpci_set_irq(zdev);

	default_restore_msi_irqs(pdev);

}



static struct airq_struct zpci_airq = {

	.handler = zpci_floating_irq_handler,

	.isc = PCI_ISC,

drivers/pci/hotplug/s390_pci_hpc.c

+24 −0
Original line number Diff line number Diff line
@@ -57,6 +57,29 @@ static int disable_slot(struct hotplug_slot *hotplug_slot) 
	return zpci_deconfigure_device(zdev);

}



static int reset_slot(struct hotplug_slot *hotplug_slot, bool probe)

{

	struct zpci_dev *zdev = container_of(hotplug_slot, struct zpci_dev,

					     hotplug_slot);



	if (zdev->state != ZPCI_FN_STATE_CONFIGURED)

		return -EIO;

	/*

	 * We can't take the zdev->lock as reset_slot may be called during

	 * probing and/or device removal which already happens under the

	 * zdev->lock. Instead the user should use the higher level

	 * pci_reset_function() or pci_bus_reset() which hold the PCI device

	 * lock preventing concurrent removal. If not using these functions

	 * holding the PCI device lock is required.

	 */



	/* As long as the function is configured we can reset */

	if (probe)

		return 0;



	return zpci_hot_reset_device(zdev);

}



static int get_power_status(struct hotplug_slot *hotplug_slot, u8 *value)

{

	struct zpci_dev *zdev = container_of(hotplug_slot, struct zpci_dev,
@@ -76,6 +99,7 @@ static int get_adapter_status(struct hotplug_slot *hotplug_slot, u8 *value) 
static const struct hotplug_slot_ops s390_hotplug_slot_ops = {

	.enable_slot =		enable_slot,

	.disable_slot =		disable_slot,

	.reset_slot =		reset_slot,

	.get_power_status =	get_power_status,

	.get_adapter_status =	get_adapter_status,

};