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Subject[PATCH v8 2/8] PCI: Add new array for keeping track of ordering of reset methods
Date
Introduce a new array reset_methods in struct pci_dev to keep track of
reset mechanisms supported by the device and their ordering.

Also refactor probing and reset functions to take advantage of calling
convention of reset functions.

Co-developed-by: Alex Williamson <alex.williamson@redhat.com>
Signed-off-by: Alex Williamson <alex.williamson@redhat.com>
Signed-off-by: Amey Narkhede <ameynarkhede03@gmail.com>
---
drivers/pci/pci.c | 97 ++++++++++++++++++++++++++-------------------
drivers/pci/pci.h | 9 ++++-
drivers/pci/probe.c | 5 +--
include/linux/pci.h | 7 ++++
4 files changed, 74 insertions(+), 44 deletions(-)

diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c
index 28f099a4f..1932c7ec4 100644
--- a/drivers/pci/pci.c
+++ b/drivers/pci/pci.c
@@ -72,6 +72,14 @@ static void pci_dev_d3_sleep(struct pci_dev *dev)
msleep(delay);
}

+int pci_reset_supported(struct pci_dev *dev)
+{
+ u8 null_reset_methods[PCI_NUM_RESET_METHODS] = { 0 };
+
+ return memcmp(null_reset_methods,
+ dev->reset_methods, sizeof(null_reset_methods));
+}
+
#ifdef CONFIG_PCI_DOMAINS
int pci_domains_supported = 1;
#endif
@@ -5101,6 +5109,19 @@ static void pci_dev_restore(struct pci_dev *dev)
err_handler->reset_done(dev);
}

+/*
+ * The ordering for functions in pci_reset_fn_methods is required for
+ * reset_methods byte array defined in struct pci_dev.
+ */
+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.
@@ -5123,65 +5144,61 @@ 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);
- if (rc != -ENOTTY)
- return rc;
- return pci_reset_bus_function(dev, 0);
+ for (i = 0; i < PCI_NUM_RESET_METHODS && (m = dev->reset_methods[i]); i++) {
+ rc = pci_reset_fn_methods[m].reset_fn(dev, 0);
+ if (!rc)
+ return 0;
+ if (rc != -ENOTTY)
+ return rc;
+ }
+
+ 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.
+ * to reads and writes to its PCI config space in order to use this function.
*
- * 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 i, n, rc;
+ u8 reset_methods[PCI_NUM_RESET_METHODS] = { 0 };

- might_sleep();
+ n = 0;

- 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;
+ BUILD_BUG_ON(ARRAY_SIZE(pci_reset_fn_methods) != PCI_NUM_RESET_METHODS);

- return pci_reset_bus_function(dev, 1);
+ might_sleep();
+
+ for (i = 1; i < PCI_NUM_RESET_METHODS; i++) {
+ rc = pci_reset_fn_methods[i].reset_fn(dev, 1);
+ if (!rc)
+ reset_methods[n++] = i;
+ else if (rc != -ENOTTY)
+ break;
+ }
+ memcpy(dev->reset_methods, reset_methods, sizeof(reset_methods));
}

/**
diff --git a/drivers/pci/pci.h b/drivers/pci/pci.h
index 37c913bbc..db1ad94e7 100644
--- a/drivers/pci/pci.h
+++ b/drivers/pci/pci.h
@@ -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);
+int 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);

@@ -606,6 +607,12 @@ 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;
+};
+
+extern const struct pci_reset_fn_method pci_reset_fn_methods[];
#ifdef CONFIG_PCI_QUIRKS
int pci_dev_specific_reset(struct pci_dev *dev, int probe);
#else
diff --git a/drivers/pci/probe.c b/drivers/pci/probe.c
index 862d91615..7355769f8 100644
--- a/drivers/pci/probe.c
+++ b/drivers/pci/probe.c
@@ -2406,9 +2406,8 @@ 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);
}

/*
diff --git a/include/linux/pci.h b/include/linux/pci.h
index 74f42a2cd..bce3d3e52 100644
--- a/include/linux/pci.h
+++ b/include/linux/pci.h
@@ -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
@@ -504,6 +507,10 @@ struct pci_dev {
char *driver_override; /* Driver name to force a match */

unsigned long priv_flags; /* Private flags for the PCI driver */
+ /*
+ * See pci_reset_fn_methods array in pci.c for ordering.
+ */
+ u8 reset_methods[PCI_NUM_RESET_METHODS]; /* Reset methods ordered by priority */
};

static inline struct pci_dev *pci_physfn(struct pci_dev *dev)
--
2.32.0
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