Hi Lorenzo,
> -----Original Message-----
> From: Lorenzo Pieralisi <lorenzo.pieralisi@xxxxxxx>
> Sent: Monday, June 21, 2021 10:23 PM
> To: Thokala, Srikanth <srikanth.thokala@xxxxxxxxx>; maz@xxxxxxxxxx
> Cc: robh+dt@xxxxxxxxxx; linux-pci@xxxxxxxxxxxxxxx;
> devicetree@xxxxxxxxxxxxxxx; andriy.shevchenko@xxxxxxxxxxxxxxx;
> mgross@xxxxxxxxxxxxxxx; Raja Subramanian, Lakshmi Bai
> <lakshmi.bai.raja.subramanian@xxxxxxxxx>; Sangannavar, Mallikarjunappa
> <mallikarjunappa.sangannavar@xxxxxxxxx>; kw@xxxxxxxxx
> Subject: Re: [PATCH v10 2/2] PCI: keembay: Add support for Intel Keem Bay
>
> [+Marc]
>
> On Mon, Jun 07, 2021 at 09:10:44PM +0530, srikanth.thokala@xxxxxxxxx
> wrote:
> [...]
>
> > +static void keembay_pcie_msi_irq_handler(struct irq_desc *desc)
> > +{
> > + struct keembay_pcie *pcie = irq_desc_get_handler_data(desc);
> > + struct irq_chip *chip = irq_desc_get_chip(desc);
> > + u32 val, mask, status;
> > + struct pcie_port *pp;
> > +
> > + chained_irq_enter(chip, desc);
> > +
> > + pp = &pcie->pci.pp;
> > + val = readl(pcie->apb_base + PCIE_REGS_INTERRUPT_STATUS);
> > + mask = readl(pcie->apb_base + PCIE_REGS_INTERRUPT_ENABLE);
> > +
> > + status = val & mask;
> > +
> > + if (status & MSI_CTRL_INT) {
> > + dw_handle_msi_irq(pp);
> > + writel(status, pcie->apb_base + PCIE_REGS_INTERRUPT_STATUS);
> > + }
> > +
> > + chained_irq_exit(chip, desc);
> > +}
> > +
> > +static int keembay_pcie_setup_msi_irq(struct keembay_pcie *pcie)
> > +{
> > + struct dw_pcie *pci = &pcie->pci;
> > + struct device *dev = pci->dev;
> > + struct platform_device *pdev = to_platform_device(dev);
> > + int irq;
> > +
> > + irq = platform_get_irq_byname(pdev, "pcie");
> > + if (irq < 0)
> > + return irq;
> > +
> > + irq_set_chained_handler_and_data(irq, keembay_pcie_msi_irq_handler,
> > + pcie);
> > +
>
> Ok this is yet another DWC MSI incantation and given that Marc worked
> hard consolidating them let's have a look before we merge it.
>
> IIUC - this IP relies on the DWC logic to handle MSIs + custom
> registers to detect a pending MSI IRQ because the logic in
> dw_chained_msi_irq() is *not* enough so you have to register
> a driver specific chained handler. This looks similar to the dra7xx
> driver MSI handling but I am not entirely convinced it is needed.
>
> I assume this code in keembay_pcie_msi_irq_handler() is required
> owing to additional IP logic on top of the standard DWC IP, in
> particular the PCIE_REGS_INTERRUPT_STATUS write to "clear" the
> IRQ.
>
> We need more insights before merging it so please provide them.
>
> pp = &pcie->pci.pp;
> val = readl(pcie->apb_base + PCIE_REGS_INTERRUPT_STATUS);
> mask = readl(pcie->apb_base + PCIE_REGS_INTERRUPT_ENABLE);
>
> status = val & mask;
>
> if (status & MSI_CTRL_INT) {
> dw_handle_msi_irq(pp);
> writel(status, pcie->apb_base + PCIE_REGS_INTERRUPT_STATUS);
> }
Yes, your understanding is correct.
Additional registers PCIE_REGS_INTERRUPT_ENABLE/_STATUS are provided
by IP to control the interrupts.
To receive MSI interrupts, SW must enable bit '8' of _ENABLE register.
And once a MSI is raised by the End point, bit '8' of _STATUS register
will be set and it needs to be cleared after servicing the interrupt.
Thanks!
Srikanth
>
> Thanks,
> Lorenzo
>
> > +static void keembay_pcie_ep_init(struct dw_pcie_ep *ep)
> > +{
> > + struct dw_pcie *pci = to_dw_pcie_from_ep(ep);
> > + struct keembay_pcie *pcie = dev_get_drvdata(pci->dev);
> > +
> > + writel(EDMA_INT_EN, pcie->apb_base + PCIE_REGS_INTERRUPT_ENABLE);
> > +}
> > +
> > +static int keembay_pcie_ep_raise_irq(struct dw_pcie_ep *ep, u8 func_no,
> > + enum pci_epc_irq_type type,
> > + u16 interrupt_num)
> > +{
> > + struct dw_pcie *pci = to_dw_pcie_from_ep(ep);
> > +
> > + switch (type) {
> > + case PCI_EPC_IRQ_LEGACY:
> > + /* Legacy interrupts are not supported in Keem Bay */
> > + dev_err(pci->dev, "Legacy IRQ is not supported\n");
> > + return -EINVAL;
> > + case PCI_EPC_IRQ_MSI:
> > + return dw_pcie_ep_raise_msi_irq(ep, func_no, interrupt_num);
> > + case PCI_EPC_IRQ_MSIX:
> > + return dw_pcie_ep_raise_msix_irq(ep, func_no, interrupt_num);
> > + default:
> > + dev_err(pci->dev, "Unknown IRQ type %d\n", type);
> > + return -EINVAL;
> > + }
> > +}
> > +
> > +static const struct pci_epc_features keembay_pcie_epc_features = {
> > + .linkup_notifier = false,
> > + .msi_capable = true,
> > + .msix_capable = true,
> > + .reserved_bar = BIT(BAR_1) | BIT(BAR_3) | BIT(BAR_5),
> > + .bar_fixed_64bit = BIT(BAR_0) | BIT(BAR_2) | BIT(BAR_4),
> > + .align = SZ_16K,
> > +};
> > +
> > +static const struct pci_epc_features *
> > +keembay_pcie_get_features(struct dw_pcie_ep *ep)
> > +{
> > + return &keembay_pcie_epc_features;
> > +}
> > +
> > +static const struct dw_pcie_ep_ops keembay_pcie_ep_ops = {
> > + .ep_init = keembay_pcie_ep_init,
> > + .raise_irq = keembay_pcie_ep_raise_irq,
> > + .get_features = keembay_pcie_get_features,
> > +};
> > +
> > +static const struct dw_pcie_host_ops keembay_pcie_host_ops = {
> > +};
> > +
> > +static int keembay_pcie_add_pcie_port(struct keembay_pcie *pcie,
> > + struct platform_device *pdev)
> > +{
> > + struct dw_pcie *pci = &pcie->pci;
> > + struct pcie_port *pp = &pci->pp;
> > + struct device *dev = &pdev->dev;
> > + u32 val;
> > + int ret;
> > +
> > + pp->ops = &keembay_pcie_host_ops;
> > + pp->msi_irq = -ENODEV;
> > +
> > + ret = keembay_pcie_setup_msi_irq(pcie);
> > + if (ret)
> > + return ret;
> > +
> > + pcie->reset = devm_gpiod_get(dev, "reset", GPIOD_OUT_HIGH);
> > + if (IS_ERR(pcie->reset))
> > + return PTR_ERR(pcie->reset);
> > +
> > + ret = keembay_pcie_probe_clocks(pcie);
> > + if (ret)
> > + return ret;
> > +
> > + val = readl(pcie->apb_base + PCIE_REGS_PCIE_PHY_CNTL);
> > + val |= PHY0_SRAM_BYPASS;
> > + writel(val, pcie->apb_base + PCIE_REGS_PCIE_PHY_CNTL);
> > +
> > + writel(PCIE_DEVICE_TYPE, pcie->apb_base + PCIE_REGS_PCIE_CFG);
> > +
> > + ret = keembay_pcie_pll_init(pcie);
> > + if (ret)
> > + return ret;
> > +
> > + val = readl(pcie->apb_base + PCIE_REGS_PCIE_CFG);
> > + writel(val | PCIE_RSTN, pcie->apb_base + PCIE_REGS_PCIE_CFG);
> > + keembay_ep_reset_deassert(pcie);
> > +
> > + ret = dw_pcie_host_init(pp);
> > + if (ret) {
> > + keembay_ep_reset_assert(pcie);
> > + dev_err(dev, "Failed to initialize host: %d\n", ret);
> > + return ret;
> > + }
> > +
> > + val = readl(pcie->apb_base + PCIE_REGS_INTERRUPT_ENABLE);
> > + if (IS_ENABLED(CONFIG_PCI_MSI))
> > + val |= MSI_CTRL_INT_EN;
> > + writel(val, pcie->apb_base + PCIE_REGS_INTERRUPT_ENABLE);
> > +
> > + return 0;
> > +}
> > +
> > +static int keembay_pcie_probe(struct platform_device *pdev)
> > +{
> > + const struct keembay_pcie_of_data *data;
> > + struct device *dev = &pdev->dev;
> > + struct keembay_pcie *pcie;
> > + struct dw_pcie *pci;
> > + enum dw_pcie_device_mode mode;
> > +
> > + data = device_get_match_data(dev);
> > + if (!data)
> > + return -ENODEV;
> > +
> > + mode = (enum dw_pcie_device_mode)data->mode;
> > +
> > + pcie = devm_kzalloc(dev, sizeof(*pcie), GFP_KERNEL);
> > + if (!pcie)
> > + return -ENOMEM;
> > +
> > + pci = &pcie->pci;
> > + pci->dev = dev;
> > + pci->ops = &keembay_pcie_ops;
> > +
> > + pcie->mode = mode;
> > +
> > + pcie->apb_base = devm_platform_ioremap_resource_byname(pdev, "apb");
> > + if (IS_ERR(pcie->apb_base))
> > + return PTR_ERR(pcie->apb_base);
> > +
> > + platform_set_drvdata(pdev, pcie);
> > +
> > + switch (pcie->mode) {
> > + case DW_PCIE_RC_TYPE:
> > + if (!IS_ENABLED(CONFIG_PCIE_KEEMBAY_HOST))
> > + return -ENODEV;
> > +
> > + return keembay_pcie_add_pcie_port(pcie, pdev);
> > + case DW_PCIE_EP_TYPE:
> > + if (!IS_ENABLED(CONFIG_PCIE_KEEMBAY_EP))
> > + return -ENODEV;
> > +
> > + pci->ep.ops = &keembay_pcie_ep_ops;
> > + return dw_pcie_ep_init(&pci->ep);
> > + default:
> > + dev_err(dev, "Invalid device type %d\n", pcie->mode);
> > + return -ENODEV;
> > + }
> > +}
> > +
> > +static const struct keembay_pcie_of_data keembay_pcie_rc_of_data = {
> > + .mode = DW_PCIE_RC_TYPE,
> > +};
> > +
> > +static const struct keembay_pcie_of_data keembay_pcie_ep_of_data = {
> > + .mode = DW_PCIE_EP_TYPE,
> > +};
> > +
> > +static const struct of_device_id keembay_pcie_of_match[] = {
> > + {
> > + .compatible = "intel,keembay-pcie",
> > + .data = &keembay_pcie_rc_of_data,
> > + },
> > + {
> > + .compatible = "intel,keembay-pcie-ep",
> > + .data = &keembay_pcie_ep_of_data,
> > + },
> > + {}
> > +};
> > +
> > +static struct platform_driver keembay_pcie_driver = {
> > + .driver = {
> > + .name = "keembay-pcie",
> > + .of_match_table = keembay_pcie_of_match,
> > + .suppress_bind_attrs = true,
> > + },
> > + .probe = keembay_pcie_probe,
> > +};
> > +builtin_platform_driver(keembay_pcie_driver);
> > --
> > 2.17.1
> >
