Commit e20afa06 authored by Amey Narkhede's avatar Amey Narkhede Committed by Bjorn Helgaas
Browse files

PCI: Add array to track reset method ordering 



Add reset_methods[] in struct pci_dev to keep track of reset mechanisms
supported by the device and their ordering.

Refactor probing and reset functions to take advantage of calling
convention of reset functions.

Co-developed-by: default avatarAlex Williamson <alex.williamson@redhat.com>
Link: https://lore.kernel.org/r/20210817180500.1253-4-ameynarkhede03@gmail.com


Signed-off-by: default avatarAlex Williamson <alex.williamson@redhat.com>
Signed-off-by: default avatarAmey Narkhede <ameynarkhede03@gmail.com>
Signed-off-by: default avatarBjorn Helgaas <bhelgaas@google.com>
Reviewed-by: default avatarRaphael Norwitz <raphael.norwitz@nutanix.com>
parent 56f107d7

drivers/pci/pci.c

+54 −40
Original line number Diff line number Diff line
@@ -73,6 +73,11 @@ static void pci_dev_d3_sleep(struct pci_dev *dev) 
		msleep(delay);

}



bool pci_reset_supported(struct pci_dev *dev)

{

	return dev->reset_methods[0] != 0;

}



#ifdef CONFIG_PCI_DOMAINS

int pci_domains_supported = 1;

#endif
@@ -5117,6 +5122,16 @@ static void pci_dev_restore(struct pci_dev *dev) 
		err_handler->reset_done(dev);

}



/* dev->reset_methods[] is a 0-terminated list of indices into this array */

static const struct pci_reset_fn_method pci_reset_fn_methods[] = {

	{ },

	{ pci_dev_specific_reset, .name = "device_specific" },

	{ pcie_reset_flr, .name = "flr" },

	{ pci_af_flr, .name = "af_flr" },

	{ pci_pm_reset, .name = "pm" },

	{ pci_reset_bus_function, .name = "bus" },

};



/**

 * __pci_reset_function_locked - reset a PCI device function while holding

 * the @dev mutex lock.
@@ -5139,65 +5154,64 @@ static void pci_dev_restore(struct pci_dev *dev) 
 */

int __pci_reset_function_locked(struct pci_dev *dev)

{

	int rc;

	int i, m, rc = -ENOTTY;



	might_sleep();



	/*

	 * A reset method returns -ENOTTY if it doesn't support this device

	 * and we should try the next method.

	 * A reset method returns -ENOTTY if it doesn't support this device and

	 * we should try the next method.

	 *

	 * If it returns 0 (success), we're finished.  If it returns any

	 * other error, we're also finished: this indicates that further

	 * reset mechanisms might be broken on the device.

	 * If it returns 0 (success), we're finished.  If it returns any other

	 * error, we're also finished: this indicates that further reset

	 * mechanisms might be broken on the device.

	 */

	rc = pci_dev_specific_reset(dev, 0);

	if (rc != -ENOTTY)

		return rc;

	rc = pcie_reset_flr(dev, 0);

	if (rc != -ENOTTY)

		return rc;

	rc = pci_af_flr(dev, 0);

	if (rc != -ENOTTY)

		return rc;

	rc = pci_pm_reset(dev, 0);

	for (i = 0; i < PCI_NUM_RESET_METHODS; i++) {

		m = dev->reset_methods[i];

		if (!m)

			return -ENOTTY;



		rc = pci_reset_fn_methods[m].reset_fn(dev, 0);

		if (!rc)

			return 0;

		if (rc != -ENOTTY)

			return rc;

	return pci_reset_bus_function(dev, 0);

	}



	return -ENOTTY;

}

EXPORT_SYMBOL_GPL(__pci_reset_function_locked);



/**

 * pci_probe_reset_function - check whether the device can be safely reset

 * @dev: PCI device to reset

 * pci_init_reset_methods - check whether device can be safely reset

 * and store supported reset mechanisms.

 * @dev: PCI device to check for reset mechanisms

 *

 * Some devices allow an individual function to be reset without affecting

 * other functions in the same device.  The PCI device must be responsive

 * to PCI config space in order to use this function.

 * other functions in the same device.  The PCI device must be in D0-D3hot

 * state.

 *

 * Returns 0 if the device function can be reset or negative if the

 * device doesn't support resetting a single function.

 * Stores reset mechanisms supported by device in reset_methods byte array

 * which is a member of struct pci_dev.

 */

int pci_probe_reset_function(struct pci_dev *dev)

void pci_init_reset_methods(struct pci_dev *dev)

{

	int rc;

	int m, i, rc;



	BUILD_BUG_ON(ARRAY_SIZE(pci_reset_fn_methods) != PCI_NUM_RESET_METHODS);



	might_sleep();



	rc = pci_dev_specific_reset(dev, 1);

	if (rc != -ENOTTY)

		return rc;

	rc = pcie_reset_flr(dev, 1);

	if (rc != -ENOTTY)

		return rc;

	rc = pci_af_flr(dev, 1);

	if (rc != -ENOTTY)

		return rc;

	rc = pci_pm_reset(dev, 1);

	if (rc != -ENOTTY)

		return rc;

	i = 0;

	for (m = 1; m < PCI_NUM_RESET_METHODS; m++) {

		rc = pci_reset_fn_methods[m].reset_fn(dev, 1);

		if (!rc)

			dev->reset_methods[i++] = m;

		else if (rc != -ENOTTY)

			break;

	}



	return pci_reset_bus_function(dev, 1);

	dev->reset_methods[i] = 0;

}



/**

drivers/pci/pci.h

+7 −1
Original line number Diff line number Diff line
@@ -33,7 +33,8 @@ enum pci_mmap_api { 
int pci_mmap_fits(struct pci_dev *pdev, int resno, struct vm_area_struct *vmai,

		  enum pci_mmap_api mmap_api);



int pci_probe_reset_function(struct pci_dev *dev);

bool pci_reset_supported(struct pci_dev *dev);

void pci_init_reset_methods(struct pci_dev *dev);

int pci_bridge_secondary_bus_reset(struct pci_dev *dev);

int pci_bus_error_reset(struct pci_dev *dev);
@@ -610,6 +611,11 @@ struct pci_dev_reset_methods { 
	int (*reset)(struct pci_dev *dev, int probe);

};



struct pci_reset_fn_method {

	int (*reset_fn)(struct pci_dev *pdev, int probe);

	char *name;

};



#ifdef CONFIG_PCI_QUIRKS

int pci_dev_specific_reset(struct pci_dev *dev, int probe);

#else

drivers/pci/probe.c

+2 −3
Original line number Diff line number Diff line
@@ -2429,9 +2429,8 @@ static void pci_init_capabilities(struct pci_dev *dev) 
	pci_rcec_init(dev);		/* Root Complex Event Collector */



	pcie_report_downtraining(dev);



	if (pci_probe_reset_function(dev) == 0)

		dev->reset_fn = 1;

	pci_init_reset_methods(dev);

	dev->reset_fn = pci_reset_supported(dev);

}



/*

include/linux/pci.h

+6 −0
Original line number Diff line number Diff line
@@ -49,6 +49,9 @@ 
			       PCI_STATUS_SIG_TARGET_ABORT | \

			       PCI_STATUS_PARITY)



/* Number of reset methods used in pci_reset_fn_methods array in pci.c */

#define PCI_NUM_RESET_METHODS 6



/*

 * The PCI interface treats multi-function devices as independent

 * devices.  The slot/function address of each device is encoded
@@ -506,6 +509,9 @@ struct pci_dev { 
	char		*driver_override; /* Driver name to force a match */



	unsigned long	priv_flags;	/* Private flags for the PCI driver */



	/* These methods index pci_reset_fn_methods[] */

	u8 reset_methods[PCI_NUM_RESET_METHODS]; /* In priority order */

};



static inline struct pci_dev *pci_physfn(struct pci_dev *dev)