[PATCH 06/14] powerpc/powernv: Add support for the cxl kernel api on the real phb

["Ian Munsie" <imunsie@au1.ibm.com>]

From: Ian Munsie <imunsie@au1.ibm.com>

This adds support for the peer model of the cxl kernel api to the
PowerNV PHB, and exports APIs to enable the mode, check if a PCI device
is attached to a PHB in this mode, and to set and get the peer AFU for
this mode.

The cxl driver will enable this mode for supported cards by calling
pnv_cxl_enable_phb_kernel_api(). This will set a flag in the PHB to note
that this mode is enabled, and switch out it's controller_ops for the
cxl version.

The cxl version of the controller_ops struct implements it's own
versions of the enable_device_hook and release_device to handle
refcounting on the peer AFU and to allocate a default context for the
device.

Once enabled, the cxl kernel API may not be disabled on a PHB. Currently
there is no safe way to disable cxl mode short of a reboot, so until
that changes there is no reason to support the disable path.

Signed-off-by: Ian Munsie <imunsie@au1.ibm.com>
---
 arch/powerpc/include/asm/pnv-pci.h        |   7 ++
 arch/powerpc/platforms/powernv/pci-cxl.c  | 112 ++++++++++++++++++++++++++++++
 arch/powerpc/platforms/powernv/pci-ioda.c |  22 +++++-
 arch/powerpc/platforms/powernv/pci.h      |  16 +++++
 4 files changed, 154 insertions(+), 3 deletions(-)

diff --git a/arch/powerpc/include/asm/pnv-pci.h b/arch/powerpc/include/asm/pnv-pci.h
index 791db1b..c47097f 100644
--- a/arch/powerpc/include/asm/pnv-pci.h
+++ b/arch/powerpc/include/asm/pnv-pci.h
@@ -38,6 +38,13 @@ int pnv_cxl_alloc_hwirq_ranges(struct cxl_irq_ranges *irqs,
 			       struct pci_dev *dev, int num);
 void pnv_cxl_release_hwirq_ranges(struct cxl_irq_ranges *irqs,
 				  struct pci_dev *dev);
+
+/* Support for the cxl kernel api on the real PHB (instead of vPHB) */
+int pnv_cxl_enable_phb_kernel_api(struct pci_controller *hose, bool enable);
+bool pnv_pci_on_cxl_phb(struct pci_dev *dev);
+struct cxl_afu *pnv_cxl_phb_to_afu(struct pci_controller *hose);
+void pnv_cxl_phb_set_peer_afu(struct pci_dev *dev, struct cxl_afu *afu);
+
 #endif
 
 #endif
diff --git a/arch/powerpc/platforms/powernv/pci-cxl.c b/arch/powerpc/platforms/powernv/pci-cxl.c
index ea8171f..2f386f5 100644
--- a/arch/powerpc/platforms/powernv/pci-cxl.c
+++ b/arch/powerpc/platforms/powernv/pci-cxl.c
@@ -7,8 +7,11 @@
  * 2 of the License, or (at your option) any later version.
  */
 
+#include <linux/module.h>
+#include <asm/pci-bridge.h>
 #include <asm/pnv-pci.h>
 #include <asm/opal.h>
+#include <misc/cxl.h>
 
 #include "pci.h"
 
@@ -161,3 +164,112 @@ int pnv_cxl_ioda_msi_setup(struct pci_dev *dev, unsigned int hwirq,
 	return 0;
 }
 EXPORT_SYMBOL(pnv_cxl_ioda_msi_setup);
+
+/*
+ * Sets flags and switches the controller ops to enable the cxl kernel api.
+ * Original the cxl kernel API operated on a virtual PHB, but certain cards
+ * such as the Mellanox CX4 use a peer model instead and for these cards the
+ * cxl kernel api will operate on the real PHB.
+ */
+int pnv_cxl_enable_phb_kernel_api(struct pci_controller *hose, bool enable)
+{
+	struct pnv_phb *phb = hose->private_data;
+	struct module *cxl_module;
+
+	if (!enable) {
+		/*
+		 * Once cxl mode is enabled on the PHB, there is currently no
+		 * known safe method to disable it again, and trying risks a
+		 * checkstop. If we can find a way to safely disable cxl mode
+		 * in the future we can revisit this, but for now the only sane
+		 * thing to do is to refuse to disable cxl mode:
+		 */
+		return -EPERM;
+	}
+
+	/*
+	 * Hold a reference to the cxl module since several PHB operations now
+	 * depend on it, and it would be insane to allow it to be removed so
+	 * long as we are in this mode (and since we can't safely disable this
+	 * mode once enabled...).
+	 */
+	mutex_lock(&module_mutex);
+	cxl_module = find_module("cxl");
+	if (cxl_module)
+		__module_get(cxl_module);
+	mutex_unlock(&module_mutex);
+	if (!cxl_module)
+		return -ENODEV;
+
+	phb->flags |= PNV_PHB_FLAG_CXL;
+	hose->controller_ops = pnv_cxl_cx4_ioda_controller_ops;
+
+	return 0;
+}
+EXPORT_SYMBOL(pnv_cxl_enable_phb_kernel_api);
+
+bool pnv_pci_on_cxl_phb(struct pci_dev *dev)
+{
+	struct pci_controller *hose = pci_bus_to_host(dev->bus);
+	struct pnv_phb *phb = hose->private_data;
+
+	return !!(phb->flags & PNV_PHB_FLAG_CXL);
+}
+EXPORT_SYMBOL(pnv_pci_on_cxl_phb);
+
+struct cxl_afu *pnv_cxl_phb_to_afu(struct pci_controller *hose)
+{
+	struct pnv_phb *phb = hose->private_data;
+
+	return (struct cxl_afu *)phb->cxl_afu;
+}
+EXPORT_SYMBOL_GPL(pnv_cxl_phb_to_afu);
+
+void pnv_cxl_phb_set_peer_afu(struct pci_dev *dev, struct cxl_afu *afu)
+{
+	struct pci_controller *hose = pci_bus_to_host(dev->bus);
+	struct pnv_phb *phb = hose->private_data;
+
+	phb->cxl_afu = afu;
+}
+EXPORT_SYMBOL_GPL(pnv_cxl_phb_set_peer_afu);
+
+bool pnv_cxl_enable_device_hook(struct pci_dev *dev)
+{
+	struct pci_controller *hose = pci_bus_to_host(dev->bus);
+	struct pnv_phb *phb = hose->private_data;
+	struct cxl_afu *afu = phb->cxl_afu;
+
+	if (!pnv_pci_enable_device_hook(dev))
+		return false;
+
+	/* No special handling for cxl function: */
+	if (PCI_FUNC(dev->devfn) == 0)
+		return true;
+
+	if (!afu) {
+		dev_WARN(&dev->dev, "Attempted to enable function > 0 on CXL PHB without a peer AFU\n");
+		return false;
+	}
+
+	dev_info(&dev->dev, "Enabling function on CXL enabled PHB with peer AFU\n");
+
+	/* Make sure the peer AFU can't go away while this device is active */
+	cxl_afu_get(afu);
+
+	return cxl_pci_associate_default_context(dev, afu);
+}
+
+void pnv_cxl_disable_device(struct pci_dev *dev)
+{
+	struct pci_controller *hose = pci_bus_to_host(dev->bus);
+	struct pnv_phb *phb = hose->private_data;
+	struct cxl_afu *afu = phb->cxl_afu;
+
+	/* No special handling for cxl function: */
+	if (PCI_FUNC(dev->devfn) == 0)
+		return;
+
+	cxl_pci_disable_device(dev);
+	cxl_afu_put(afu);
+}
diff --git a/arch/powerpc/platforms/powernv/pci-ioda.c b/arch/powerpc/platforms/powernv/pci-ioda.c
index e0d8103..467085f 100644
--- a/arch/powerpc/platforms/powernv/pci-ioda.c
+++ b/arch/powerpc/platforms/powernv/pci-ioda.c
@@ -3222,7 +3222,7 @@ static resource_size_t pnv_pci_iov_resource_alignment(struct pci_dev *pdev,
 /* Prevent enabling devices for which we couldn't properly
  * assign a PE
  */
-static bool pnv_pci_enable_device_hook(struct pci_dev *dev)
+bool pnv_pci_enable_device_hook(struct pci_dev *dev)
 {
 	struct pci_controller *hose = pci_bus_to_host(dev->bus);
 	struct pnv_phb *phb = hose->private_data;
@@ -3396,7 +3396,7 @@ static void pnv_ioda_release_pe(struct pnv_ioda_pe *pe)
 	pnv_ioda_free_pe(pe);
 }
 
-static void pnv_pci_release_device(struct pci_dev *pdev)
+void pnv_pci_release_device(struct pci_dev *pdev)
 {
 	struct pci_controller *hose = pci_bus_to_host(pdev->bus);
 	struct pnv_phb *phb = hose->private_data;
@@ -3423,7 +3423,7 @@ static void pnv_pci_ioda_shutdown(struct pci_controller *hose)
 		       OPAL_ASSERT_RESET);
 }
 
-static const struct pci_controller_ops pnv_pci_ioda_controller_ops = {
+const struct pci_controller_ops pnv_pci_ioda_controller_ops = {
 	.dma_dev_setup		= pnv_pci_dma_dev_setup,
 	.dma_bus_setup		= pnv_pci_dma_bus_setup,
 #ifdef CONFIG_PCI_MSI
@@ -3461,6 +3461,22 @@ static const struct pci_controller_ops pnv_npu_ioda_controller_ops = {
 	.shutdown		= pnv_pci_ioda_shutdown,
 };
 
+#ifdef CONFIG_CXL_BASE
+const struct pci_controller_ops pnv_cxl_cx4_ioda_controller_ops = {
+	.dma_dev_setup		= pnv_pci_dma_dev_setup,
+	.dma_bus_setup		= pnv_pci_dma_bus_setup,
+	.enable_device_hook	= pnv_cxl_enable_device_hook,
+	.disable_device		= pnv_cxl_disable_device,
+	.release_device		= pnv_pci_release_device,
+	.window_alignment	= pnv_pci_window_alignment,
+	.setup_bridge		= pnv_pci_setup_bridge,
+	.reset_secondary_bus	= pnv_pci_reset_secondary_bus,
+	.dma_set_mask		= pnv_pci_ioda_dma_set_mask,
+	.dma_get_required_mask	= pnv_pci_ioda_dma_get_required_mask,
+	.shutdown		= pnv_pci_ioda_shutdown,
+};
+#endif
+
 static void __init pnv_pci_init_ioda_phb(struct device_node *np,
 					 u64 hub_id, int ioda_type)
 {
diff --git a/arch/powerpc/platforms/powernv/pci.h b/arch/powerpc/platforms/powernv/pci.h
index 49c2997..4d003dc 100644
--- a/arch/powerpc/platforms/powernv/pci.h
+++ b/arch/powerpc/platforms/powernv/pci.h
@@ -76,6 +76,7 @@ struct pnv_ioda_pe {
 };
 
 #define PNV_PHB_FLAG_EEH	(1 << 0)
+#define PNV_PHB_FLAG_CXL	(1 << 1) /* Real PHB supporting the cxl kernel API */
 
 struct pnv_phb {
 	struct pci_controller	*hose;
@@ -177,6 +178,9 @@ struct pnv_phb {
 		struct OpalIoP7IOCErrorData 	hub_diag;
 	} diag;
 
+#ifdef CONFIG_CXL_BASE
+	struct cxl_afu *cxl_afu;
+#endif
 };
 
 extern struct pci_ops pnv_pci_ops;
@@ -218,6 +222,8 @@ extern int pnv_setup_msi_irqs(struct pci_dev *pdev, int nvec, int type);
 extern void pnv_teardown_msi_irqs(struct pci_dev *pdev);
 extern struct pnv_ioda_pe *pnv_ioda_get_pe(struct pci_dev *dev);
 extern void pnv_set_msi_irq_chip(struct pnv_phb *phb, unsigned int virq);
+extern bool pnv_pci_enable_device_hook(struct pci_dev *dev);
+extern void pnv_pci_release_device(struct pci_dev *pdev);
 
 extern void pe_level_printk(const struct pnv_ioda_pe *pe, const char *level,
 			    const char *fmt, ...);
@@ -238,4 +244,14 @@ extern long pnv_npu_unset_window(struct pnv_ioda_pe *npe, int num);
 extern void pnv_npu_take_ownership(struct pnv_ioda_pe *npe);
 extern void pnv_npu_release_ownership(struct pnv_ioda_pe *npe);
 
+
+/* cxl functions */
+extern bool pnv_cxl_enable_device_hook(struct pci_dev *dev);
+extern void pnv_cxl_disable_device(struct pci_dev *dev);
+
+
+/* phb ops (cxl switches these when enabling the kernel api on the phb) */
+extern const struct pci_controller_ops pnv_cxl_cx4_ioda_controller_ops;
+extern const struct pci_controller_ops pnv_pci_ioda_controller_ops;
+
 #endif /* __POWERNV_PCI_H */
-- 
2.8.1