ice: add ice_adapter for shared data across PFs on the same NIC

There is a need for synchronization between ice PFs on the same physical
adapter.

Add a "struct ice_adapter" for holding data shared between PFs of the
same multifunction PCI device. The struct is refcounted - each ice_pf
holds a reference to it.

Its first use will be for PTP. I expect it will be useful also to
improve the ugliness that is ice_prot_id_tbl.

Reviewed-by: Przemek Kitszel <przemyslaw.kitszel@intel.com>
Signed-off-by: Michal Schmidt <mschmidt@redhat.com>
Tested-by: Pucha Himasekhar Reddy <himasekharx.reddy.pucha@intel.com> (A Contingent worker at Intel)
Signed-off-by: Tony Nguyen <anthony.l.nguyen@intel.com>

drivers/net/ethernet/intel/ice/Makefile

@@ -36,7 +36,8 @@ ice-y := ice_main.o	\
 	 ice_repr.o	\
 	 ice_tc_lib.o	\
 	 ice_fwlog.o	\
-	 ice_debugfs.o
+	 ice_debugfs.o  \
+	 ice_adapter.o
 ice-$(CONFIG_PCI_IOV) +=	\
 	ice_sriov.o		\
 	ice_virtchnl.o		\

drivers/net/ethernet/intel/ice/ice.h

@@ -77,6 +77,7 @@
 #include "ice_gnss.h"
 #include "ice_irq.h"
 #include "ice_dpll.h"
+#include "ice_adapter.h"
 
 #define ICE_BAR0		0
 #define ICE_REQ_DESC_MULTIPLE	32
@@ -537,6 +538,7 @@ struct ice_agg_node {
 
 struct ice_pf {
 	struct pci_dev *pdev;
+	struct ice_adapter *adapter;
 
 	struct devlink_region *nvm_region;
 	struct devlink_region *sram_region;

drivers/net/ethernet/intel/ice/ice_adapter.c

@@ -0,0 +1,114 @@
+// SPDX-License-Identifier: GPL-2.0-only
+// SPDX-FileCopyrightText: Copyright Red Hat
+
+#include <linux/bitfield.h>
+#include <linux/cleanup.h>
+#include <linux/mutex.h>
+#include <linux/pci.h>
+#include <linux/slab.h>
+#include <linux/xarray.h>
+#include "ice_adapter.h"
+
+static DEFINE_XARRAY(ice_adapters);
+
+/* PCI bus number is 8 bits. Slot is 5 bits. Domain can have the rest. */
+#define INDEX_FIELD_DOMAIN GENMASK(BITS_PER_LONG - 1, 13)
+#define INDEX_FIELD_BUS    GENMASK(12, 5)
+#define INDEX_FIELD_SLOT   GENMASK(4, 0)
+
+static unsigned long ice_adapter_index(const struct pci_dev *pdev)
+{
+	unsigned int domain = pci_domain_nr(pdev->bus);
+
+	WARN_ON(domain > FIELD_MAX(INDEX_FIELD_DOMAIN));
+
+	return FIELD_PREP(INDEX_FIELD_DOMAIN, domain) |
+	       FIELD_PREP(INDEX_FIELD_BUS,    pdev->bus->number) |
+	       FIELD_PREP(INDEX_FIELD_SLOT,   PCI_SLOT(pdev->devfn));
+}
+
+static struct ice_adapter *ice_adapter_new(void)
+{
+	struct ice_adapter *adapter;
+
+	adapter = kzalloc(sizeof(*adapter), GFP_KERNEL);
+	if (!adapter)
+		return NULL;
+
+	refcount_set(&adapter->refcount, 1);
+
+	return adapter;
+}
+
+static void ice_adapter_free(struct ice_adapter *adapter)
+{
+	kfree(adapter);
+}
+
+DEFINE_FREE(ice_adapter_free, struct ice_adapter*, if (_T) ice_adapter_free(_T))
+
+/**
+ * ice_adapter_get - Get a shared ice_adapter structure.
+ * @pdev: Pointer to the pci_dev whose driver is getting the ice_adapter.
+ *
+ * Gets a pointer to a shared ice_adapter structure. Physical functions (PFs)
+ * of the same multi-function PCI device share one ice_adapter structure.
+ * The ice_adapter is reference-counted. The PF driver must use ice_adapter_put
+ * to release its reference.
+ *
+ * Context: Process, may sleep.
+ * Return:  Pointer to ice_adapter on success.
+ *          ERR_PTR() on error. -ENOMEM is the only possible error.
+ */
+struct ice_adapter *ice_adapter_get(const struct pci_dev *pdev)
+{
+	struct ice_adapter *ret, __free(ice_adapter_free) *adapter = NULL;
+	unsigned long index = ice_adapter_index(pdev);
+
+	adapter = ice_adapter_new();
+	if (!adapter)
+		return ERR_PTR(-ENOMEM);
+
+	xa_lock(&ice_adapters);
+	ret = __xa_cmpxchg(&ice_adapters, index, NULL, adapter, GFP_KERNEL);
+	if (xa_is_err(ret)) {
+		ret = ERR_PTR(xa_err(ret));
+		goto unlock;
+	}
+	if (ret) {
+		refcount_inc(&ret->refcount);
+		goto unlock;
+	}
+	ret = no_free_ptr(adapter);
+unlock:
+	xa_unlock(&ice_adapters);
+	return ret;
+}
+
+/**
+ * ice_adapter_put - Release a reference to the shared ice_adapter structure.
+ * @pdev: Pointer to the pci_dev whose driver is releasing the ice_adapter.
+ *
+ * Releases the reference to ice_adapter previously obtained with
+ * ice_adapter_get.
+ *
+ * Context: Any.
+ */
+void ice_adapter_put(const struct pci_dev *pdev)
+{
+	unsigned long index = ice_adapter_index(pdev);
+	struct ice_adapter *adapter;
+
+	xa_lock(&ice_adapters);
+	adapter = xa_load(&ice_adapters, index);
+	if (WARN_ON(!adapter))
+		goto unlock;
+
+	if (!refcount_dec_and_test(&adapter->refcount))
+		goto unlock;
+
+	WARN_ON(__xa_erase(&ice_adapters, index) != adapter);
+	ice_adapter_free(adapter);
+unlock:
+	xa_unlock(&ice_adapters);
+}

drivers/net/ethernet/intel/ice/ice_adapter.h

@@ -0,0 +1,22 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+/* SPDX-FileCopyrightText: Copyright Red Hat */
+
+#ifndef _ICE_ADAPTER_H_
+#define _ICE_ADAPTER_H_
+
+#include <linux/refcount_types.h>
+
+struct pci_dev;
+
+/**
+ * struct ice_adapter - PCI adapter resources shared across PFs
+ * @refcount: Reference count. struct ice_pf objects hold the references.
+ */
+struct ice_adapter {
+	refcount_t refcount;
+};
+
+struct ice_adapter *ice_adapter_get(const struct pci_dev *pdev);
+void ice_adapter_put(const struct pci_dev *pdev);
+
+#endif /* _ICE_ADAPTER_H */

drivers/net/ethernet/intel/ice/ice_main.c

@@ -5093,6 +5093,7 @@ static int
 ice_probe(struct pci_dev *pdev, const struct pci_device_id __always_unused *ent)
 {
 	struct device *dev = &pdev->dev;
+	struct ice_adapter *adapter;
 	struct ice_pf *pf;
 	struct ice_hw *hw;
 	int err;
@@ -5145,7 +5146,12 @@ ice_probe(struct pci_dev *pdev, const struct pci_device_id __always_unused *ent)
 
 	pci_set_master(pdev);
 
+	adapter = ice_adapter_get(pdev);
+	if (IS_ERR(adapter))
+		return PTR_ERR(adapter);
+
 	pf->pdev = pdev;
+	pf->adapter = adapter;
 	pci_set_drvdata(pdev, pf);
 	set_bit(ICE_DOWN, pf->state);
 	/* Disable service task until DOWN bit is cleared */
@@ -5196,6 +5202,7 @@ ice_probe(struct pci_dev *pdev, const struct pci_device_id __always_unused *ent)
 err_load:
 	ice_deinit(pf);
 err_init:
+	ice_adapter_put(pdev);
 	pci_disable_device(pdev);
 	return err;
 }
@@ -5302,6 +5309,7 @@ static void ice_remove(struct pci_dev *pdev)
 	ice_setup_mc_magic_wake(pf);
 	ice_set_wake(pf);
 
+	ice_adapter_put(pdev);
 	pci_disable_device(pdev);
 }