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Message-ID: <20230902045328.GB2913@thinkpad>
Date: Sat, 2 Sep 2023 10:23:28 +0530
From: Manivannan Sadhasivam <manivannan.sadhasivam@...aro.org>
To: Frank Li <Frank.Li@....com>
Cc: tglx@...utronix.de, aisheng.dong@....com, bhelgaas@...gle.com,
devicetree@...r.kernel.org, festevam@...il.com,
imx@...ts.linux.dev, jdmason@...zu.us, kernel@...gutronix.de,
kishon@...com, krzysztof.kozlowski+dt@...aro.org, kw@...ux.com,
linux-arm-kernel@...ts.infradead.org, linux-imx@....com,
linux-kernel@...r.kernel.org, linux-pci@...r.kernel.org,
lorenzo.pieralisi@....com, lpieralisi@...nel.org, maz@...nel.org,
ntb@...ts.linux.dev, peng.fan@....com, robh+dt@...nel.org,
s.hauer@...gutronix.de, shawnguo@...nel.org
Subject: Re: [PATCH 1/3] PCI: endpoint: Add RC-to-EP doorbell support using
platform MSI controller
On Sat, Sep 02, 2023 at 10:22:25AM +0530, Manivannan Sadhasivam wrote:
> On Wed, Apr 26, 2023 at 04:34:34PM -0400, Frank Li wrote:
> > This commit introduces a common method for sending messages from the Root Complex
> > (RC) to the Endpoint (EP) by utilizing the platform MSI interrupt controller,
> > such as ARM GIC, as an EP doorbell. Maps the memory assigned for the BAR region
> > by the PCI host to the message address of the platform MSI interrupt controller
> > in the PCI EP. As a result, when the PCI RC writes to the BAR region, it triggers
> > an IRQ at the EP. This implementation serves as a common method for all endpoint
> > function drivers.
> >
> > However, it currently supports only one EP physical function due to limitations
> > in ARM MSI/IMS readiness.
> >
>
> I've provided generic comments below, but I will do one more thorough review
> after seeing epf-test driver patch.
>
> > Signed-off-by: Frank Li <Frank.Li@....com>
> > ---
> > drivers/pci/endpoint/pci-epf-core.c | 109 ++++++++++++++++++++++++++++
> > include/linux/pci-epf.h | 16 ++++
> > 2 files changed, 125 insertions(+)
> >
> > diff --git a/drivers/pci/endpoint/pci-epf-core.c b/drivers/pci/endpoint/pci-epf-core.c
> > index 355a6f56fcea..94ac82bf84c5 100644
> > --- a/drivers/pci/endpoint/pci-epf-core.c
> > +++ b/drivers/pci/endpoint/pci-epf-core.c
> > @@ -6,10 +6,12 @@
> > * Author: Kishon Vijay Abraham I <kishon@...com>
> > */
> >
> > +#include <linux/irqreturn.h>
>
> Why is this needed?
>
> > #include <linux/device.h>
> > #include <linux/dma-mapping.h>
> > #include <linux/slab.h>
> > #include <linux/module.h>
> > +#include <linux/msi.h>
> >
> > #include <linux/pci-epc.h>
> > #include <linux/pci-epf.h>
> > @@ -300,6 +302,113 @@ void *pci_epf_alloc_space(struct pci_epf *epf, size_t size, enum pci_barno bar,
> > }
> > EXPORT_SYMBOL_GPL(pci_epf_alloc_space);
> >
> > +static enum irqreturn pci_epf_interrupt_handler(int irq, void *data)
>
> static irqreturn_t
>
> s/pci_epf_interrupt_handler/pci_epf_doorbell_handler
>
> > +{
> > + struct pci_epf *epf = data;
> > +
> > + if (epf->event_ops && epf->event_ops->doorbell)
> > + epf->event_ops->doorbell(epf, irq - epf->virq_base);
> > +
> > + return IRQ_HANDLED;
> > +}
> > +
> > +static void pci_epf_write_msi_msg(struct msi_desc *desc, struct msi_msg *msg)
> > +{
> > + struct pci_epc *epc = container_of(desc->dev, struct pci_epc, dev);
> > + struct pci_epf *epf;
> > +
> > + /* Todo: Need check correct epf if multi epf supported */
> > + list_for_each_entry(epf, &epc->pci_epf, list) {
> > + if (epf->msg && desc->msi_index < epf->num_msgs)
> > + epf->msg[desc->msi_index] = *msg;
> > + }
> > +}
> > +
> > +int pci_epf_alloc_doorbell(struct pci_epf *epf, u16 num_msgs)
> > +{
> > + struct irq_domain *domain;
> > + struct pci_epc *epc;
> > + struct device *dev;
> > + int virq;
> > + int ret;
> > + int i;
> > +
> > + epc = epf->epc;
> > + dev = &epc->dev;
>
> "epc_dev" to make it explicit
>
> > +
> > + /*
> > + * Current only support 1 function.
>
> What does this mean exactly? Even a single EPC can support multiple EPFs
>
Please ignore above comment.
- Mani
> > + * PCI IMS(interrupt message store) ARM support have not been
> > + * ready yet.
>
> No need to mention platform irq controller name.
>
> > + */
> > + if (epc->function_num_map != 1)
>
> Why can't you use, epf->func_no?
>
> > + return -EOPNOTSUPP;
> > +
> > + domain = dev_get_msi_domain(dev->parent);
> > + if (!domain)
> > + return -EOPNTSUPP;
>
> Newline
>
> > + dev_set_msi_domain(dev, domain);
> > +
> > + /* use parent of_node to get device id information */
> > + dev->of_node = dev->parent->of_node;
> > +
>
> Why do you need of_node assignment inside EPF core?
>
> > + epf->msg = kcalloc(num_msgs, sizeof(struct msi_msg), GFP_KERNEL);
> > + if (!epf->msg)
> > + return -ENOMEM;
> > +
> > + epf->num_msgs = num_msgs;
> > +
>
> Move this to the start of the function, after checks.
>
> > + ret = platform_msi_domain_alloc_irqs(dev, num_msgs, pci_epf_write_msi_msg);
> > + if (ret) {
> > + dev_err(dev, "Can't allocate MSI from system MSI controller\n");
>
> "Failed to allocate MSI"
>
> > + goto err_mem;
>
> err_free_mem
>
> > + }
> > +
> > + for (i = 0; i < num_msgs; i++) {
> > + virq = msi_get_virq(dev, i);
> > + if (i == 0)
> > + epf->virq_base = virq;
> > +
> > + ret = request_irq(virq, pci_epf_interrupt_handler, 0,
> > + "pci-epf-doorbell", epf);
>
> IRQ name should have an index, otherwise all of them will have the same name.
>
> > +
> > + if (ret) {
> > + dev_err(dev, "Failure request doorbell IRQ\n");
>
> "Failed to request doorbell"
>
> > + goto err_irq;
>
> err_free_irq
>
> > + }
> > + }
> > +
> > + epf->num_msgs = num_msgs;
>
> Newline
>
> > + return ret;
> > +
> > +err_irq:
> > + platform_msi_domain_free_irqs(dev);
> > +err_mem:
> > + kfree(epf->msg);
> > + epf->msg = NULL;
> > + epf->num_msgs = 0;
> > +
> > + return ret;
> > +}
> > +EXPORT_SYMBOL_GPL(pci_epf_alloc_doorbell);
> > +
> > +void pci_epf_free_doorbell(struct pci_epf *epf)
> > +{
> > + struct pci_epc *epc;
> > + int i;
> > +
> > + epc = epf->epc;
> > +
> > + for (i = 0; i < epf->num_msgs; i++)
> > + free_irq(epf->virq_base + i, epf);
> > +
> > + platform_msi_domain_free_irqs(&epc->dev);
> > + kfree(epf->msg);
> > + epf->msg = NULL;
> > + epf->num_msgs = 0;
> > +}
> > +EXPORT_SYMBOL_GPL(pci_epf_free_doorbell);
> > +
> > static void pci_epf_remove_cfs(struct pci_epf_driver *driver)
> > {
> > struct config_group *group, *tmp;
> > diff --git a/include/linux/pci-epf.h b/include/linux/pci-epf.h
> > index b8441db2fa52..e187e3ee48d2 100644
> > --- a/include/linux/pci-epf.h
> > +++ b/include/linux/pci-epf.h
> > @@ -75,6 +75,7 @@ struct pci_epf_ops {
> > struct pci_epc_event_ops {
> > int (*core_init)(struct pci_epf *epf);
> > int (*link_up)(struct pci_epf *epf);
> > + int (*doorbell)(struct pci_epf *epf, int index);
> > };
> >
> > /**
> > @@ -173,6 +174,9 @@ struct pci_epf {
> > unsigned long vfunction_num_map;
> > struct list_head pci_vepf;
> > const struct pci_epc_event_ops *event_ops;
> > + struct msi_msg *msg;
> > + u16 num_msgs;
> > + int virq_base;
> > };
> >
> > /**
> > @@ -216,4 +220,16 @@ int pci_epf_bind(struct pci_epf *epf);
> > void pci_epf_unbind(struct pci_epf *epf);
> > int pci_epf_add_vepf(struct pci_epf *epf_pf, struct pci_epf *epf_vf);
> > void pci_epf_remove_vepf(struct pci_epf *epf_pf, struct pci_epf *epf_vf);
> > +int pci_epf_alloc_doorbell(struct pci_epf *epf, u16 nums);
> > +void pci_epf_free_doorbell(struct pci_epf *epf);
> > +
> > +static inline struct msi_msg *epf_get_msg(struct pci_epf *epf)
> > +{
> > + return epf->msg;
> > +}
> > +
> > +static inline u16 epf_get_msg_num(struct pci_epf *epf)
> > +{
> > + return epf->num_msgs;
> > +}
>
> I don't see a need for these two functions as they are doing just dereferences.
>
> - Mani
>
> > #endif /* __LINUX_PCI_EPF_H */
> > --
> > 2.34.1
> >
>
> --
> மணிவண்ணன் சதாசிவம்
--
மணிவண்ணன் சதாசிவம்
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