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Message-ID: <ebc129b7-b671-475b-423a-f6545c18849b@quicinc.com>
Date: Fri, 8 Nov 2024 06:23:07 +0530
From: Krishna Chaitanya Chundru <quic_krichai@...cinc.com>
To: Frank Li <Frank.Li@....com>,
Manivannan Sadhasivam
<manivannan.sadhasivam@...aro.org>,
Krzysztof Wilczyński
<kw@...ux.com>,
Kishon Vijay Abraham I <kishon@...nel.org>,
Bjorn Helgaas
<bhelgaas@...gle.com>, Arnd Bergmann <arnd@...db.de>,
Greg Kroah-Hartman
<gregkh@...uxfoundation.org>
CC: <linux-kernel@...r.kernel.org>, <linux-pci@...r.kernel.org>,
<imx@...ts.linux.dev>, Niklas Cassel <cassel@...nel.org>,
<dlemoal@...nel.org>, <maz@...nel.org>, <tglx@...utronix.de>,
<jdmason@...zu.us>
Subject: Re: [PATCH v4 2/5] PCI: endpoint: Add RC-to-EP doorbell support using
platform MSI controller
On 10/31/2024 9:57 PM, Frank Li wrote:
> Doorbell feature is implemented by mapping the EP's MSI interrupt
> controller message address to a dedicated BAR in the EPC core. It is the
> responsibility of the EPF driver to pass the actual message data to be
> written by the host to the doorbell BAR region through its own logic.
>
Hi Frank,
Currently you are using single doorbell callback for all MSI's
received from the host side.
Instead of that can we expose a API which will be used by EPF driver
to request for IRQ by passing there own irq handler. we can skip
request_irq in epc_alloc_doorbell expose a seperate API for the
EPF driver to request_IRQ or let the EPF driver do request_irq by
filling epf->db_msg[i].virq
- Krishna Chaitanya.
> Signed-off-by: Frank Li <Frank.Li@....com>
> ---
> Change from v3 to v4
> - msi change to use msi_get_virq() avoid use msi_for_each_desc().
> - add new struct for pci_epf_doorbell_msg to msi msg,virq and irq name.
> - move mutex lock to epc function
> - initialize variable at declear place.
> - passdown epf to epc*() function to simplify code.
> ---
> drivers/pci/endpoint/Makefile | 2 +-
> drivers/pci/endpoint/pci-ep-msi.c | 128 ++++++++++++++++++++++++++++++++++++++
> include/linux/pci-ep-msi.h | 15 +++++
> include/linux/pci-epf.h | 19 ++++++
> 4 files changed, 163 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/pci/endpoint/Makefile b/drivers/pci/endpoint/Makefile
> index 95b2fe47e3b06..a1ccce440c2c5 100644
> --- a/drivers/pci/endpoint/Makefile
> +++ b/drivers/pci/endpoint/Makefile
> @@ -5,4 +5,4 @@
>
> 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/
> + pci-epc-mem.o pci-ep-msi.o functions/
> diff --git a/drivers/pci/endpoint/pci-ep-msi.c b/drivers/pci/endpoint/pci-ep-msi.c
> new file mode 100644
> index 0000000000000..91207fb66db32
> --- /dev/null
> +++ b/drivers/pci/endpoint/pci-ep-msi.c
> @@ -0,0 +1,128 @@
> +// SPDX-License-Identifier: GPL-2.0
> +/*
> + * PCI Endpoint *Controller* (EPC) MSI library
> + *
> + * Copyright (C) 2024 NXP
> + * Author: Frank Li <Frank.Li@....com>
> + */
> +
> +#include <linux/cleanup.h>
> +#include <linux/device.h>
> +#include <linux/slab.h>
> +#include <linux/module.h>
> +#include <linux/msi.h>
> +#include <linux/pci-epc.h>
> +#include <linux/pci-epf.h>
> +#include <linux/pci-ep-cfs.h>
> +#include <linux/pci-ep-msi.h>
> +
> +static irqreturn_t pci_epf_doorbell_handler(int irq, void *data)
> +{
> + struct pci_epf *epf = data;
> + struct msi_desc *desc = irq_get_msi_desc(irq);
> +
> + if (desc && epf->event_ops && epf->event_ops->doorbell)
> + epf->event_ops->doorbell(epf, desc->msi_index);
> +
> + return IRQ_HANDLED;
> +}
> +
> +static bool pci_epc_match_parent(struct device *dev, void *param)
> +{
> + return dev->parent == param;
> +}
> +
> +static void pci_epc_write_msi_msg(struct msi_desc *desc, struct msi_msg *msg)
> +{
> + struct pci_epc *epc __free(pci_epc_put) = NULL;
> + struct pci_epf *epf;
> +
> + epc = pci_epc_get_fn(pci_epc_match_parent, desc->dev);
> + if (!epc)
> + return;
> +
> + /* Only support one EPF for doorbell */
> + 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));
> +}
> +
> +static void pci_epc_free_doorbell(struct pci_epc *epc, struct pci_epf *epf)
> +{
> + int i;
> +
> + guard(mutex)(&epc->lock);
> +
> + for (i = 0; i < epf->num_db && epf->db_msg[i].virq; i++) {
> + free_irq(epf->db_msg[i].virq, epf);
> + epf->db_msg[i].virq = 0;
> + kfree(epf->db_msg[i].name);
> + epf->db_msg[i].name = NULL;
> + }
> +
> + platform_device_msi_free_irqs_all(epc->dev.parent);
> +}
> +
> +static int pci_epc_alloc_doorbell(struct pci_epc *epc, struct pci_epf *epf)
> +{
> + struct device *dev = epc->dev.parent;
> + u16 num_db = epf->num_db;
> + int i = 0;
> + int ret;
> +
> + guard(mutex)(&epc->lock);
> +
> + ret = platform_device_msi_init_and_alloc_irqs(dev, num_db, pci_epc_write_msi_msg);
> + if (ret) {
> + dev_err(dev, "Failed to allocate MSI\n");
> + return -ENOMEM;
> + }
> +
> + for (i = 0; i < num_db; i++) {
> + epf->db_msg[i].virq = msi_get_virq(dev, i);
> + epf->db_msg[i].name = kasprintf(GFP_KERNEL, "pci-epc-doorbell%d", i);
> + ret = request_irq(epf->db_msg[i].virq, pci_epf_doorbell_handler, 0,
> + epf->db_msg[i].name, epf);
> + if (ret) {
> + dev_err(dev, "Failed to request doorbell\n");
> + pci_epc_free_doorbell(epc, epf);
> + return ret;
> + }
> + }
> +
> + return 0;
> +};
> +
> +int pci_epf_alloc_doorbell(struct pci_epf *epf, u16 num_db)
> +{
> + struct pci_epc *epc = epf->epc;
> + void *msg;
> + int ret;
> +
> + 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 = pci_epc_alloc_doorbell(epc, epf);
> + if (ret)
> + kfree(msg);
> +
> + return ret;
> +}
> +EXPORT_SYMBOL_GPL(pci_epf_alloc_doorbell);
> +
> +void pci_epf_free_doorbell(struct pci_epf *epf)
> +{
> + struct pci_epc *epc = epf->epc;
> +
> + pci_epc_free_doorbell(epc, epf);
> +
> + 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..f0cfecf491199
> --- /dev/null
> +++ b/include/linux/pci-ep-msi.h
> @@ -0,0 +1,15 @@
> +/* SPDX-License-Identifier: GPL-2.0 */
> +/*
> + * PCI Endpoint *Function* side MSI header file
> + *
> + * Copyright (C) 2024 NXP
> + * Author: Frank Li <Frank.Li@....com>
> + */
> +
> +#ifndef __PCI_EP_MSI__
> +#define __PCI_EP_MSI__
> +
> +int pci_epf_alloc_doorbell(struct pci_epf *epf, u16 nums);
> +void pci_epf_free_doorbell(struct pci_epf *epf);
> +
> +#endif /* __PCI_EP_MSI__ */
> diff --git a/include/linux/pci-epf.h b/include/linux/pci-epf.h
> index 18a3aeb62ae4e..50c0f877f2efb 100644
> --- a/include/linux/pci-epf.h
> +++ b/include/linux/pci-epf.h
> @@ -12,6 +12,7 @@
> #include <linux/configfs.h>
> #include <linux/device.h>
> #include <linux/mod_devicetable.h>
> +#include <linux/msi.h>
> #include <linux/pci.h>
>
> struct pci_epf;
> @@ -75,6 +76,7 @@ struct pci_epf_ops {
> * @link_up: Callback for the EPC link up event
> * @link_down: Callback for the EPC link down event
> * @bus_master_enable: Callback for the EPC Bus Master Enable event
> + * @doorbell: Callback for EPC receive MSI from RC side
> */
> struct pci_epc_event_ops {
> int (*epc_init)(struct pci_epf *epf);
> @@ -82,6 +84,7 @@ struct pci_epc_event_ops {
> int (*link_up)(struct pci_epf *epf);
> int (*link_down)(struct pci_epf *epf);
> int (*bus_master_enable)(struct pci_epf *epf);
> + int (*doorbell)(struct pci_epf *epf, int index);
> };
>
> /**
> @@ -125,6 +128,18 @@ struct pci_epf_bar {
> int flags;
> };
>
> +/**
> + * struct pci_epf_doorbell_msg - represents doorbell message
> + * @msi_msg: MSI message
> + * @virq: irq number of this doorbell MSI message
> + * @name: irq name for doorbell interrupt
> + */
> +struct pci_epf_doorbell_msg {
> + struct msi_msg msg;
> + int virq;
> + char *name;
> +};
> +
> /**
> * struct pci_epf - represents the PCI EPF device
> * @dev: the PCI EPF device
> @@ -152,6 +167,8 @@ 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;
> @@ -182,6 +199,8 @@ 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;
> };
>
> /**
>
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