RE: [PATCH v18 18/20] PCI: rcar-gen4-ep: Add R-Car Gen4 PCIe Endpoint support

[Yoshihiro Shimoda <yoshihiro.shimoda.uh@renesas.com>]

Hi Serge,

> From: Serge Semin, Sent: Tuesday, August 1, 2023 10:36 AM
> To: Yoshihiro Shimoda <yoshihiro.shimoda.uh@renesas.com>
> Cc: jingoohan1@gmail.com; gustavo.pimentel@synopsys.com; lpieralisi@kernel.org; robh+dt@kernel.org; kw@linux.com;
> manivannan.sadhasivam@linaro.org; bhelgaas@google.com; kishon@kernel.org; krzysztof.kozlowski+dt@linaro.org;
> conor+dt@kernel.org; marek.vasut+renesas@gmail.com; linux-pci@vger.kernel.org; devicetree@vger.kernel.org;
> linux-renesas-soc@vger.kernel.org
> Subject: Re: [PATCH v18 18/20] PCI: rcar-gen4-ep: Add R-Car Gen4 PCIe Endpoint support
> 
> On Fri, Jul 21, 2023 at 04:44:50PM +0900, Yoshihiro Shimoda wrote:
> > Add R-Car Gen4 PCIe Endpoint support. This controller is based on
> > Synopsys DesignWare PCIe.
> >
> > Signed-off-by: Yoshihiro Shimoda <yoshihiro.shimoda.uh@renesas.com>
> > ---
> >  drivers/pci/controller/dwc/Kconfig            |   9 +
> >  drivers/pci/controller/dwc/Makefile           |   2 +
> >  .../pci/controller/dwc/pcie-rcar-gen4-ep.c    | 189 ++++++++++++++++++
> >  3 files changed, 200 insertions(+)
> >  create mode 100644 drivers/pci/controller/dwc/pcie-rcar-gen4-ep.c
> >
> > diff --git a/drivers/pci/controller/dwc/Kconfig b/drivers/pci/controller/dwc/Kconfig
> > index 64d4d37bc891..4d877cd18374 100644
> > --- a/drivers/pci/controller/dwc/Kconfig
> > +++ b/drivers/pci/controller/dwc/Kconfig
> > @@ -424,4 +424,13 @@ config PCIE_RCAR_GEN4
> >  	  Say Y here if you want PCIe host controller support on R-Car Gen4 SoCs.
> >  	  This uses the DesignWare core.
> >
> > +config PCIE_RCAR_GEN4_EP
> > +	tristate "Renesas R-Car Gen4 PCIe Endpoint controller"
> > +	depends on ARCH_RENESAS || COMPILE_TEST
> > +	depends on PCI_ENDPOINT
> > +	select PCIE_DW_EP
> > +	help
> > +	  Say Y here if you want PCIe endpoint controller support on R-Car Gen4
> > +	  SoCs. This uses the DesignWare core.
> > +
> >  endmenu
> > diff --git a/drivers/pci/controller/dwc/Makefile b/drivers/pci/controller/dwc/Makefile
> > index 486cf706b53d..0fb0bde26ac4 100644
> > --- a/drivers/pci/controller/dwc/Makefile
> > +++ b/drivers/pci/controller/dwc/Makefile
> > @@ -28,6 +28,8 @@ obj-$(CONFIG_PCIE_UNIPHIER_EP) += pcie-uniphier-ep.o
> >  obj-$(CONFIG_PCIE_VISCONTI_HOST) += pcie-visconti.o
> >  pcie-rcar-gen4-host-drv-objs := pcie-rcar-gen4.o pcie-rcar-gen4-host.o
> >  obj-$(CONFIG_PCIE_RCAR_GEN4) += pcie-rcar-gen4-host-drv.o
> > +pcie-rcar-gen4-ep-drv-objs := pcie-rcar-gen4.o pcie-rcar-gen4-ep.o
> > +obj-$(CONFIG_PCIE_RCAR_GEN4_EP) += pcie-rcar-gen4-ep-drv.o
> >
> >  # The following drivers are for devices that use the generic ACPI
> >  # pci_root.c driver but don't support standard ECAM config access.
> > diff --git a/drivers/pci/controller/dwc/pcie-rcar-gen4-ep.c b/drivers/pci/controller/dwc/pcie-rcar-gen4-ep.c
> > new file mode 100644
> > index 000000000000..3970a920f3fe
> > --- /dev/null
> > +++ b/drivers/pci/controller/dwc/pcie-rcar-gen4-ep.c
> > @@ -0,0 +1,189 @@
> > +// SPDX-License-Identifier: GPL-2.0-only
> > +/*
> > + * PCIe Endpoint driver for Renesas R-Car Gen4 Series SoCs
> > + * Copyright (C) 2022-2023 Renesas Electronics Corporation
> > + */
> > +
> > +#include <linux/interrupt.h>
> > +#include <linux/module.h>
> > +#include <linux/of_device.h>
> > +#include <linux/pci.h>
> > +#include <linux/platform_device.h>
> > +
> > +#include "pcie-rcar-gen4.h"
> > +#include "pcie-designware.h"
> > +
> > +#define RCAR_GEN4_PCIE_EP_FUNC_DBI_OFFSET	0x1000
> > +#define RCAR_GEN4_PCIE_EP_FUNC_DBI2_OFFSET	0x800
> > +
> > +static void rcar_gen4_pcie_ep_pre_init(struct dw_pcie_ep *ep)
> > +{
> > +	struct dw_pcie *dw = to_dw_pcie_from_ep(ep);
> > +	struct rcar_gen4_pcie *rcar = to_rcar_gen4_pcie(dw);
> > +	int ret;
> > +
> > +	ret = clk_bulk_prepare_enable(DW_PCIE_NUM_CORE_CLKS, dw->core_clks);
> > +	if (ret) {
> > +		dev_err(dw->dev, "Failed to enable ref clocks\n");
> > +		return;
> > +	}
> > +
> > +	rcar_gen4_pcie_basic_init(rcar);
> > +
> > +	writel(PCIEDMAINTSTSEN_INIT, rcar->base + PCIEDMAINTSTSEN);
> > +}
> > +
> > +static void rcar_gen4_pcie_ep_init(struct dw_pcie_ep *ep)
> > +{
> > +	struct dw_pcie *pci = to_dw_pcie_from_ep(ep);
> > +	enum pci_barno bar;
> > +
> > +	for (bar = 0; bar < PCI_STD_NUM_BARS; bar++)
> > +		dw_pcie_ep_reset_bar(pci, bar);
> > +}
> > +
> > +static void rcar_gen4_pcie_ep_deinit(struct dw_pcie_ep *ep)
> > +{
> > +	struct dw_pcie *dw = to_dw_pcie_from_ep(ep);
> > +	struct rcar_gen4_pcie *rcar = to_rcar_gen4_pcie(dw);
> > +
> > +	writel(0, rcar->base + PCIEDMAINTSTSEN);
> > +	rcar_gen4_pcie_basic_deinit(rcar);
> > +	clk_bulk_disable_unprepare(DW_PCIE_NUM_CORE_CLKS, dw->core_clks);
> > +}
> > +
> > +static int rcar_gen4_pcie_ep_raise_irq(struct dw_pcie_ep *ep, u8 func_no,
> > +				       enum pci_epc_irq_type type,
> > +				       u16 interrupt_num)
> > +{
> > +	struct dw_pcie *dw = to_dw_pcie_from_ep(ep);
> > +
> > +	switch (type) {
> > +	case PCI_EPC_IRQ_INTX:
> > +		return dw_pcie_ep_raise_intx_irq(ep, func_no);
> > +	case PCI_EPC_IRQ_MSI:
> > +		return dw_pcie_ep_raise_msi_irq(ep, func_no, interrupt_num);
> > +	default:
> > +		dev_err(dw->dev, "Unknown IRQ type\n");
> > +		return -EINVAL;
> > +	}
> > +
> > +	return 0;
> > +}
> > +
> > +static const struct pci_epc_features rcar_gen4_pcie_epc_features = {
> > +	.linkup_notifier = false,
> > +	.msi_capable = true,
> > +	.msix_capable = false,
> > +	.reserved_bar = 1 << BAR_1 | 1 << BAR_3 | 1 << BAR_5,
> > +	.align = SZ_1M,
> > +};
> > +
> > +static const struct pci_epc_features*
> > +rcar_gen4_pcie_ep_get_features(struct dw_pcie_ep *ep)
> > +{
> > +	return &rcar_gen4_pcie_epc_features;
> > +}
> > +
> > +static unsigned int rcar_gen4_pcie_ep_func_conf_select(struct dw_pcie_ep *ep,
> > +						       u8 func_no)
> > +{
> > +	return func_no * RCAR_GEN4_PCIE_EP_FUNC_DBI_OFFSET;
> > +}
> > +
> > +static unsigned int rcar_gen4_pcie_ep_func_conf_select2(struct dw_pcie_ep *ep,
> > +							u8 func_no)
> > +{
> > +	return func_no * RCAR_GEN4_PCIE_EP_FUNC_DBI2_OFFSET;
> > +}
> > +
> > +static const struct dw_pcie_ep_ops pcie_ep_ops = {
> > +	.ep_pre_init = rcar_gen4_pcie_ep_pre_init,
> > +	.ep_init = rcar_gen4_pcie_ep_init,
> > +	.ep_deinit = rcar_gen4_pcie_ep_deinit,
> > +	.raise_irq = rcar_gen4_pcie_ep_raise_irq,
> > +	.get_features = rcar_gen4_pcie_ep_get_features,
> > +	.func_conf_select = rcar_gen4_pcie_ep_func_conf_select,
> > +	.func_conf_select2 = rcar_gen4_pcie_ep_func_conf_select2,
> > +};
> > +
> > +static int rcar_gen4_add_pcie_ep(struct rcar_gen4_pcie *rcar,
> 
> > +				 struct platform_device *pdev)
> 
> Drop this argument. rcar already has the pdev pointer.

Oops. I'll fix it.

> > +{
> > +	struct dw_pcie_ep *ep = &rcar->dw.ep;
> > +	int ret;
> > +
> > +	rcar->mode = DW_PCIE_EP_TYPE;
> > +	ep->ops = &pcie_ep_ops;
> > +
> > +	ret = dw_pcie_ep_init(ep);
> > +	if (ret) {
> 
> > +		dev_err(&pdev->dev, "Failed to initialize endpoint\n");
> 
> Even though half the DW PCIe EP LLDDs are doing the same I would have
> either dropped the error printed here or converted it to
> dev_err_probe(). First option is more preferable because thus your RP
> and EP adding methods will turn to look similar.

I prefer keeping dev_err_probe() here because it's possible to fail without
any error message, IIUC.

> > +		return ret;
> > +	}
> > +
> > +	return 0;
> > +}
> > +
> > +static void rcar_gen4_remove_pcie_ep(struct rcar_gen4_pcie *rcar)
> > +{
> > +	dw_pcie_ep_exit(&rcar->dw.ep);
> > +}
> > +
> > +static int rcar_gen4_pcie_ep_probe(struct platform_device *pdev)
> > +{
> > +	struct device *dev = &pdev->dev;
> > +	struct rcar_gen4_pcie *rcar;
> > +	int err;
> > +
> > +	rcar = rcar_gen4_pcie_devm_alloc(pdev);
> > +	if (!rcar)
> > +		return -ENOMEM;
> > +
> > +	err = rcar_gen4_pcie_get_resources(rcar);
> 
> > +	if (err < 0) {
> 
> As Mani correctly noticed the checks should be converted to "if (err)...".

I got it.

> > +		dev_err(dev, "Failed to request resource: %d\n", err);
> 
> I would have moved this error printed to the
> rcar_gen4_pcie_get_resources() method (similar fix should be in the
> Root Port patch too). Thus the probe method will turn to look neat and
> you'll be able to drop the dev pointer from here.

I got it. I'll fix them.

> > +		return err;
> > +	}
> > +
> > +	err = rcar_gen4_pcie_prepare(rcar);
> 
> > +	if (err < 0)
> 
> if (err) ?
> 
> > +		return err;
> > +
> > +	err = rcar_gen4_add_pcie_ep(rcar, pdev);
> 
> > +	if (err < 0)
> 
> ditto

I'll fix them as "if(err)"

> > +		goto err_add;
> > +
> > +	return 0;
> > +
> 
> > +err_add:
> 
> See the comments in the patch 17/20 regarding the label name.

I'll rename the label to "err_unprepare".

> > +	rcar_gen4_pcie_unprepare(rcar);
> > +
> > +	return err;
> > +}
> > +
> > +static void rcar_gen4_pcie_ep_remove(struct platform_device *pdev)
> > +{
> > +	struct rcar_gen4_pcie *rcar = platform_get_drvdata(pdev);
> > +
> > +	rcar_gen4_remove_pcie_ep(rcar);
> > +	rcar_gen4_pcie_unprepare(rcar);
> > +}
> > +
> > +static const struct of_device_id rcar_gen4_pcie_of_match[] = {
> > +	{ .compatible = "renesas,rcar-gen4-pcie-ep", },
> > +	{},
> > +};
> 
> As Mani noted: missing MODULE_DEVICE_TABLE().

I got it.

Best regards,
Yoshihiro Shimoda

> -Serge(y)
> 
> > +
> > +static struct platform_driver rcar_gen4_pcie_ep_driver = {
> > +	.driver = {
> > +		.name = "pcie-rcar-gen4-ep",
> > +		.of_match_table = rcar_gen4_pcie_of_match,
> > +	},
> > +	.probe = rcar_gen4_pcie_ep_probe,
> > +	.remove_new = rcar_gen4_pcie_ep_remove,
> > +};
> > +module_platform_driver(rcar_gen4_pcie_ep_driver);
> > +
> > +MODULE_DESCRIPTION("Renesas R-Car Gen4 PCIe endpoint controller driver");
> > +MODULE_LICENSE("GPL");
> > --
> > 2.25.1
> >