From 1c3b002c6bf684b445a7107609979bca5f21bc03 Mon Sep 17 00:00:00 2001 From: Frank Li Date: Thu, 10 Jul 2025 15:13:49 -0400 Subject: [PATCH] PCI: endpoint: Add RC-to-EP doorbell support using platform MSI controller Implement the doorbell feature by mapping the EP's MSI interrupt controller message address to a dedicated BAR. The EPF driver should pass the actual message data to be written to the message address by the host through implementation-specific logic. Signed-off-by: Frank Li [mani: minor code cleanups and reworded commit message] Signed-off-by: Manivannan Sadhasivam [bhelgaas: fix kernel-doc] Signed-off-by: Bjorn Helgaas Tested-by: Niklas Cassel Link: https://patch.msgid.link/20250710-ep-msi-v21-3-57683fc7fb25@nxp.com --- drivers/pci/endpoint/Kconfig | 8 +++ drivers/pci/endpoint/Makefile | 1 + drivers/pci/endpoint/pci-ep-msi.c | 92 +++++++++++++++++++++++++++++++ include/linux/pci-ep-msi.h | 28 ++++++++++ include/linux/pci-epf.h | 15 +++++ 5 files changed, 144 insertions(+) create mode 100644 drivers/pci/endpoint/pci-ep-msi.c create mode 100644 include/linux/pci-ep-msi.h diff --git a/drivers/pci/endpoint/Kconfig b/drivers/pci/endpoint/Kconfig index 1c5d82eb57d44..8dad291be8b80 100644 --- a/drivers/pci/endpoint/Kconfig +++ b/drivers/pci/endpoint/Kconfig @@ -28,6 +28,14 @@ config PCI_ENDPOINT_CONFIGFS configure the endpoint function and used to bind the function with an endpoint controller. +config PCI_ENDPOINT_MSI_DOORBELL + bool "PCI Endpoint MSI Doorbell Support" + depends on PCI_ENDPOINT && GENERIC_MSI_IRQ + help + This enables the EP's MSI interrupt controller to function as a + doorbell. The RC can trigger doorbell in EP by writing data to a + dedicated BAR, which the EP maps to the controller's message address. + source "drivers/pci/endpoint/functions/Kconfig" endmenu diff --git a/drivers/pci/endpoint/Makefile b/drivers/pci/endpoint/Makefile index 95b2fe47e3b06..b4869d52053aa 100644 --- a/drivers/pci/endpoint/Makefile +++ b/drivers/pci/endpoint/Makefile @@ -6,3 +6,4 @@ obj-$(CONFIG_PCI_ENDPOINT_CONFIGFS) += pci-ep-cfs.o obj-$(CONFIG_PCI_ENDPOINT) += pci-epc-core.o pci-epf-core.o\ pci-epc-mem.o functions/ +obj-$(CONFIG_PCI_ENDPOINT_MSI_DOORBELL) += pci-ep-msi.o diff --git a/drivers/pci/endpoint/pci-ep-msi.c b/drivers/pci/endpoint/pci-ep-msi.c new file mode 100644 index 0000000000000..95a47ce155ace --- /dev/null +++ b/drivers/pci/endpoint/pci-ep-msi.c @@ -0,0 +1,92 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * PCI Endpoint *Controller* (EPC) MSI library + * + * Copyright (C) 2025 NXP + * Author: Frank Li + */ + +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include + +static void pci_epf_write_msi_msg(struct msi_desc *desc, struct msi_msg *msg) +{ + struct pci_epc *epc; + struct pci_epf *epf; + + epc = pci_epc_get(dev_name(msi_desc_to_dev(desc))); + if (!epc) + return; + + epf = list_first_entry_or_null(&epc->pci_epf, struct pci_epf, list); + + if (epf && epf->db_msg && desc->msi_index < epf->num_db) + memcpy(&epf->db_msg[desc->msi_index].msg, msg, sizeof(*msg)); + + pci_epc_put(epc); +} + +int pci_epf_alloc_doorbell(struct pci_epf *epf, u16 num_db) +{ + struct pci_epc *epc = epf->epc; + struct device *dev = &epf->dev; + struct irq_domain *domain; + void *msg; + int ret; + int i; + + /* TODO: Multi-EPF support */ + if (list_first_entry_or_null(&epc->pci_epf, struct pci_epf, list) != epf) { + dev_err(dev, "MSI doorbell doesn't support multiple EPF\n"); + return -EINVAL; + } + + domain = of_msi_map_get_device_domain(epc->dev.parent, 0, + DOMAIN_BUS_PLATFORM_MSI); + if (!domain) { + dev_err(dev, "Can't find MSI domain for EPC\n"); + return -ENODEV; + } + + dev_set_msi_domain(epc->dev.parent, domain); + + msg = kcalloc(num_db, sizeof(struct pci_epf_doorbell_msg), GFP_KERNEL); + if (!msg) + return -ENOMEM; + + epf->num_db = num_db; + epf->db_msg = msg; + + ret = platform_device_msi_init_and_alloc_irqs(epc->dev.parent, num_db, + pci_epf_write_msi_msg); + if (ret) { + dev_err(dev, "Failed to allocate MSI\n"); + kfree(msg); + return ret; + } + + for (i = 0; i < num_db; i++) + epf->db_msg[i].virq = msi_get_virq(epc->dev.parent, i); + + return ret; +} +EXPORT_SYMBOL_GPL(pci_epf_alloc_doorbell); + +void pci_epf_free_doorbell(struct pci_epf *epf) +{ + platform_device_msi_free_irqs_all(epf->epc->dev.parent); + + kfree(epf->db_msg); + epf->db_msg = NULL; + epf->num_db = 0; +} +EXPORT_SYMBOL_GPL(pci_epf_free_doorbell); diff --git a/include/linux/pci-ep-msi.h b/include/linux/pci-ep-msi.h new file mode 100644 index 0000000000000..7c5db90f96204 --- /dev/null +++ b/include/linux/pci-ep-msi.h @@ -0,0 +1,28 @@ +/* SPDX-License-Identifier: GPL-2.0 */ +/* + * PCI Endpoint *Function* side MSI header file + * + * Copyright (C) 2024 NXP + * Author: Frank Li + */ + +#ifndef __PCI_EP_MSI__ +#define __PCI_EP_MSI__ + +struct pci_epf; + +#ifdef CONFIG_PCI_ENDPOINT_MSI_DOORBELL +int pci_epf_alloc_doorbell(struct pci_epf *epf, u16 nums); +void pci_epf_free_doorbell(struct pci_epf *epf); +#else +static inline int pci_epf_alloc_doorbell(struct pci_epf *epf, u16 nums) +{ + return -ENODATA; +} + +static inline void pci_epf_free_doorbell(struct pci_epf *epf) +{ +} +#endif /* CONFIG_GENERIC_MSI_IRQ */ + +#endif /* __PCI_EP_MSI__ */ diff --git a/include/linux/pci-epf.h b/include/linux/pci-epf.h index 749cee0bcf2cc..52e07602f08e8 100644 --- a/include/linux/pci-epf.h +++ b/include/linux/pci-epf.h @@ -12,6 +12,7 @@ #include #include #include +#include #include struct pci_epf; @@ -128,6 +129,16 @@ struct pci_epf_bar { int flags; }; +/** + * struct pci_epf_doorbell_msg - represents doorbell message + * @msg: MSI message + * @virq: IRQ number of this doorbell MSI message + */ +struct pci_epf_doorbell_msg { + struct msi_msg msg; + int virq; +}; + /** * struct pci_epf - represents the PCI EPF device * @dev: the PCI EPF device @@ -155,6 +166,8 @@ struct pci_epf_bar { * @vfunction_num_map: bitmap to manage virtual function number * @pci_vepf: list of virtual endpoint functions associated with this function * @event_ops: callbacks for capturing the EPC events + * @db_msg: data for MSI from RC side + * @num_db: number of doorbells */ struct pci_epf { struct device dev; @@ -185,6 +198,8 @@ struct pci_epf { unsigned long vfunction_num_map; struct list_head pci_vepf; const struct pci_epc_event_ops *event_ops; + struct pci_epf_doorbell_msg *db_msg; + u16 num_db; }; /** -- 2.47.2