Re: [PATCH v19 16/19] PCI: rcar-gen4: Add R-Car Gen4 PCIe Host support

[Serge Semin <fancer.lancer@gmail.com>]

On Wed, Aug 23, 2023 at 06:11:50PM +0900, Yoshihiro Shimoda wrote:
> Add R-Car Gen4 PCIe Host support. This controller is based on
> Synopsys DesignWare PCIe, but this controller has vendor-specific
> registers so that requires initialization code like mode setting
> and retraining and so on.
> 
> To reduce code delta, adds some helper functions which are used by
> both the host driver and the endpoint driver (which is added
> immediately afterwards) into a separate file.
> 
> Signed-off-by: Yoshihiro Shimoda <yoshihiro.shimoda.uh@renesas.com>
> ---
>  drivers/pci/controller/dwc/Kconfig            |  10 +
>  drivers/pci/controller/dwc/Makefile           |   2 +
>  .../controller/dwc/pcie-rcar-gen4-host-drv.c  | 145 ++++++++++++
>  drivers/pci/controller/dwc/pcie-rcar-gen4.c   | 208 ++++++++++++++++++
>  drivers/pci/controller/dwc/pcie-rcar-gen4.h   |  44 ++++
>  5 files changed, 409 insertions(+)
>  create mode 100644 drivers/pci/controller/dwc/pcie-rcar-gen4-host-drv.c
>  create mode 100644 drivers/pci/controller/dwc/pcie-rcar-gen4.c
>  create mode 100644 drivers/pci/controller/dwc/pcie-rcar-gen4.h
> 
> diff --git a/drivers/pci/controller/dwc/Kconfig b/drivers/pci/controller/dwc/Kconfig
> index ab96da43e0c2..3884a67e4d56 100644
> --- a/drivers/pci/controller/dwc/Kconfig
> +++ b/drivers/pci/controller/dwc/Kconfig
> @@ -415,4 +415,14 @@ config PCIE_VISCONTI_HOST
>  	  Say Y here if you want PCIe controller support on Toshiba Visconti SoC.
>  	  This driver supports TMPV7708 SoC.
>  
> +config PCIE_RCAR_GEN4
> +	tristate "Renesas R-Car Gen4 PCIe Host controller"
> +	depends on ARCH_RENESAS || COMPILE_TEST
> +	depends on PCI_MSI
> +	select PCIE_DW_HOST
> +	help
> +	  Say Y here if you want PCIe host controller support on R-Car Gen4 SoCs.
> +	  To compile this driver as a module, choose M here: the module will be
> +	  called pcie-rcar-gen4-host.ko. This uses the DesignWare core.
> +
>  endmenu
> diff --git a/drivers/pci/controller/dwc/Makefile b/drivers/pci/controller/dwc/Makefile
> index bf5c311875a1..ab2c6bc16216 100644
> --- a/drivers/pci/controller/dwc/Makefile
> +++ b/drivers/pci/controller/dwc/Makefile
> @@ -26,6 +26,8 @@ obj-$(CONFIG_PCIE_TEGRA194) += pcie-tegra194.o
>  obj-$(CONFIG_PCIE_UNIPHIER) += pcie-uniphier.o
>  obj-$(CONFIG_PCIE_UNIPHIER_EP) += pcie-uniphier-ep.o
>  obj-$(CONFIG_PCIE_VISCONTI_HOST) += pcie-visconti.o
> +pcie-rcar-gen4-host-objs := pcie-rcar-gen4.o pcie-rcar-gen4-host-drv.o
> +obj-$(CONFIG_PCIE_RCAR_GEN4) += pcie-rcar-gen4-host.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-host-drv.c b/drivers/pci/controller/dwc/pcie-rcar-gen4-host-drv.c
> new file mode 100644
> index 000000000000..8acce1ee5efc
> --- /dev/null
> +++ b/drivers/pci/controller/dwc/pcie-rcar-gen4-host-drv.c
> @@ -0,0 +1,145 @@
> +// SPDX-License-Identifier: GPL-2.0-only
> +/*
> + * PCIe host controller driver for Renesas R-Car Gen4 Series SoCs
> + * Copyright (C) 2022-2023 Renesas Electronics Corporation
> + */
> +
> +#include <linux/delay.h>
> +#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"
> +
> +static int rcar_gen4_pcie_host_init(struct dw_pcie_rp *pp)
> +{
> +	struct dw_pcie *dw = to_dw_pcie_from_pp(pp);
> +	struct rcar_gen4_pcie *rcar = to_rcar_gen4_pcie(dw);
> +	int ret;
> +	u32 val;
> +
> +	gpiod_set_value_cansleep(dw->pe_rst, 1);
> +

> +	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 ret;
> +	}

This is called in both the Host and End-point init function right
above the rcar_gen4_pcie_common_init() method invocation. It can be moved
there then.

> +
> +	ret = rcar_gen4_pcie_common_init(rcar);
> +	if (ret) {
> +		clk_bulk_disable_unprepare(DW_PCIE_NUM_CORE_CLKS, dw->core_clks);
> +		return ret;
> +	}
> +
> +	/*
> +	 * According to the section 3.5.7.2 "RC Mode" in DWC PCIe Dual Mode
> +	 * Rev.5.20a, we should disable two BARs to avoid unnecessary memory
> +	 * assignment during device enumeration.
> +	 */
> +	dw_pcie_writel_dbi2(dw, PCI_BASE_ADDRESS_0, 0x0);
> +	dw_pcie_writel_dbi2(dw, PCI_BASE_ADDRESS_1, 0x0);
> +
> +	/* Enable MSI interrupt signal */
> +	val = readl(rcar->base + PCIEINTSTS0EN);
> +	val |= MSI_CTRL_INT;
> +	writel(val, rcar->base + PCIEINTSTS0EN);
> +
> +	msleep(100);	/* pe_rst requires 100msec delay */
> +
> +	gpiod_set_value_cansleep(dw->pe_rst, 0);
> +
> +	return 0;
> +}
> +
> +static void rcar_gen4_pcie_host_deinit(struct dw_pcie_rp *pp)
> +{
> +	struct dw_pcie *dw = to_dw_pcie_from_pp(pp);
> +	struct rcar_gen4_pcie *rcar = to_rcar_gen4_pcie(dw);
> +
> +	gpiod_set_value_cansleep(dw->pe_rst, 1);
> +	rcar_gen4_pcie_common_deinit(rcar);

> +	clk_bulk_disable_unprepare(DW_PCIE_NUM_CORE_CLKS, dw->core_clks);

and this can be moved to rcar_gen4_pcie_common_deinit() too for
the same reason as denoted in the previous comment.

> +}
> +
> +static const struct dw_pcie_host_ops rcar_gen4_pcie_host_ops = {
> +	.host_init = rcar_gen4_pcie_host_init,
> +	.host_deinit = rcar_gen4_pcie_host_deinit,
> +};
> +
> +static int rcar_gen4_add_dw_pcie_rp(struct rcar_gen4_pcie *rcar)
> +{
> +	struct dw_pcie_rp *pp = &rcar->dw.pp;
> +
> +	pp->num_vectors = MAX_MSI_IRQS;
> +	pp->ops = &rcar_gen4_pcie_host_ops;
> +	rcar->mode = DW_PCIE_RC_TYPE;
> +
> +	return dw_pcie_host_init(pp);
> +}
> +
> +static void rcar_gen4_remove_dw_pcie_rp(struct rcar_gen4_pcie *rcar)
> +{

> +	dw_pcie_host_deinit(&rcar->dw.pp);
> +	gpiod_set_value_cansleep(rcar->dw.pe_rst, 1);

gpiod_set_value_cansleep() seems redundant here because
dw_pcie_host_deinit() calls host_deinit() which is
rcar_gen4_pcie_host_deinit() and which already asserts the PE_RST
GPIO.

BTW even though after dropping the gpiod_set_value_cansleep() function
call from rcar_gen4_remove_dw_pcie_rp(), the later will be left with
only a single function invocation I would have left it defined anyway
for the internal driver interface consistency and maintainability:
you'll have a protagonist and respective antagonist defined in a way
it's done for host_init()/host_deinit(),
common_init()/common_deinit(), prepare()/unprepare(), etc. In addition
such design would simplify possible updates should you need to
extend rcar_gen4_add_dw_pcie_rp() functionality and add new cleanups
afterwards.

> +}
> +
> +static int rcar_gen4_pcie_probe(struct platform_device *pdev)
> +{
> +	struct rcar_gen4_pcie *rcar;
> +	int err;
> +
> +	rcar = rcar_gen4_pcie_devm_alloc(pdev);
> +	if (IS_ERR(rcar))
> +		return PTR_ERR(rcar);
> +
> +	err = rcar_gen4_pcie_get_resources(rcar);
> +	if (err)
> +		return err;
> +
> +	err = rcar_gen4_pcie_prepare(rcar);
> +	if (err)
> +		return err;
> +
> +	err = rcar_gen4_add_dw_pcie_rp(rcar);
> +	if (err)
> +		goto err_unprepare;
> +
> +	return 0;
> +
> +err_unprepare:
> +	rcar_gen4_pcie_unprepare(rcar);
> +
> +	return err;
> +}

Look how neat and beautiful the probe() method is now. So is the rest
of the driver.) So to speak with the previous notes fixed feel free to
add:

Reviewed-by: Serge Semin <fancer.lancer@gmail.com>

-Serge(y)

> +
> +static void rcar_gen4_pcie_remove(struct platform_device *pdev)
> +{
> +	struct rcar_gen4_pcie *rcar = platform_get_drvdata(pdev);
> +
> +	rcar_gen4_remove_dw_pcie_rp(rcar);
> +	rcar_gen4_pcie_unprepare(rcar);
> +}
> +
> +static const struct of_device_id rcar_gen4_pcie_of_match[] = {
> +	{ .compatible = "renesas,rcar-gen4-pcie", },
> +	{},
> +};
> +MODULE_DEVICE_TABLE(of, rcar_gen4_pcie_of_match);
> +
> +static struct platform_driver rcar_gen4_pcie_driver = {
> +	.driver = {
> +		.name = "pcie-rcar-gen4",
> +		.of_match_table = rcar_gen4_pcie_of_match,
> +		.probe_type = PROBE_PREFER_ASYNCHRONOUS,
> +	},
> +	.probe = rcar_gen4_pcie_probe,
> +	.remove_new = rcar_gen4_pcie_remove,
> +};
> +module_platform_driver(rcar_gen4_pcie_driver);
> +
> +MODULE_DESCRIPTION("Renesas R-Car Gen4 PCIe host controller driver");
> +MODULE_LICENSE("GPL");
> diff --git a/drivers/pci/controller/dwc/pcie-rcar-gen4.c b/drivers/pci/controller/dwc/pcie-rcar-gen4.c
> new file mode 100644
> index 000000000000..2a8bbf928d5f
> --- /dev/null
> +++ b/drivers/pci/controller/dwc/pcie-rcar-gen4.c
> @@ -0,0 +1,208 @@
> +// SPDX-License-Identifier: GPL-2.0-only
> +/*
> + * PCIe host/endpoint controller driver for Renesas R-Car Gen4 Series SoCs
> + * Copyright (C) 2022-2023 Renesas Electronics Corporation
> + */
> +
> +#include <linux/delay.h>
> +#include <linux/io.h>
> +#include <linux/of_device.h>
> +#include <linux/pci.h>
> +#include <linux/pm_runtime.h>
> +#include <linux/reset.h>
> +
> +#include "pcie-rcar-gen4.h"
> +#include "pcie-designware.h"
> +
> +/* Renesas-specific */
> +#define PCIERSTCTRL1		0x0014
> +#define APP_HOLD_PHY_RST	BIT(16)
> +#define APP_LTSSM_ENABLE	BIT(0)
> +
> +#define RCAR_NUM_SPEED_CHANGE_RETRIES	10
> +#define RCAR_MAX_LINK_SPEED		4
> +
> +static void rcar_gen4_pcie_ltssm_enable(struct rcar_gen4_pcie *rcar,
> +					bool enable)
> +{
> +	u32 val;
> +
> +	val = readl(rcar->base + PCIERSTCTRL1);
> +	if (enable) {
> +		val |= APP_LTSSM_ENABLE;
> +		val &= ~APP_HOLD_PHY_RST;
> +	} else {
> +		/*
> +		 * Since the datasheet of R-Car doesn't mention how to assert
> +		 * the APP_HOLD_PHY_RST, don't assert it again. Otherwise,
> +		 * hang-up issue happened in the dw_edma_core_off() when
> +		 * the controller didn't detect a PCI device.
> +		 */
> +		val &= ~APP_LTSSM_ENABLE;
> +	}
> +	writel(val, rcar->base + PCIERSTCTRL1);
> +}
> +
> +static int rcar_gen4_pcie_link_up(struct dw_pcie *dw)
> +{
> +	struct rcar_gen4_pcie *rcar = to_rcar_gen4_pcie(dw);
> +	u32 val, mask;
> +
> +	val = readl(rcar->base + PCIEINTSTS0);
> +	mask = RDLH_LINK_UP | SMLH_LINK_UP;
> +
> +	return (val & mask) == mask;
> +}
> +
> +/*
> + * Manually initiate the speed change. Return true if the change succeeded,
> + * false if the change didn't finish within certain periods.
> + */
> +static bool rcar_gen4_pcie_speed_change(struct dw_pcie *dw)
> +{
> +	u32 val;
> +	int i;
> +
> +	val = dw_pcie_readl_dbi(dw, PCIE_LINK_WIDTH_SPEED_CONTROL);
> +	val &= ~PORT_LOGIC_SPEED_CHANGE;
> +	dw_pcie_writel_dbi(dw, PCIE_LINK_WIDTH_SPEED_CONTROL, val);
> +
> +	val = dw_pcie_readl_dbi(dw, PCIE_LINK_WIDTH_SPEED_CONTROL);
> +	val |= PORT_LOGIC_SPEED_CHANGE;
> +	dw_pcie_writel_dbi(dw, PCIE_LINK_WIDTH_SPEED_CONTROL, val);
> +
> +	for (i = 0; i < RCAR_NUM_SPEED_CHANGE_RETRIES; i++) {
> +		val = dw_pcie_readl_dbi(dw, PCIE_LINK_WIDTH_SPEED_CONTROL);
> +		if (!(val & PORT_LOGIC_SPEED_CHANGE))
> +			return true;
> +		usleep_range(10000, 11000);
> +	}
> +
> +	return false;
> +}
> +
> +/*
> + * Enable LTSSM of this controller and manually initiate the speed change.
> + * Always return true.
> + */
> +static int rcar_gen4_pcie_start_link(struct dw_pcie *dw)
> +{
> +	struct rcar_gen4_pcie *rcar = to_rcar_gen4_pcie(dw);
> +	int i, changes;
> +
> +	rcar_gen4_pcie_ltssm_enable(rcar, true);
> +
> +	/*
> +	 * Require direct speed change with retrying here if the link_gen is
> +	 * PCIe Gen2 or higher.
> +	 */
> +	changes = min_not_zero(dw->link_gen, RCAR_MAX_LINK_SPEED) - 1;
> +
> +	/*
> +	 * Since dw_pcie_setup_rc() sets it once, PCIe Gen2 will be trained.
> +	 * So, this needs remaining times for up to PCIe Gen4 if RC mode.
> +	 */
> +	if (changes && rcar->mode == DW_PCIE_RC_TYPE)
> +		changes--;
> +
> +	for (i = 0; i < changes; i++) {
> +		if (!rcar_gen4_pcie_speed_change(dw))
> +			break;	/* No error because possible disconnected here if EP mode */
> +	}
> +
> +	return 0;
> +}
> +
> +static void rcar_gen4_pcie_stop_link(struct dw_pcie *dw)
> +{
> +	struct rcar_gen4_pcie *rcar = to_rcar_gen4_pcie(dw);
> +
> +	rcar_gen4_pcie_ltssm_enable(rcar, false);
> +}
> +
> +int rcar_gen4_pcie_common_init(struct rcar_gen4_pcie *rcar)
> +{
> +	struct dw_pcie *dw = &rcar->dw;
> +	u32 val;
> +
> +	if (!reset_control_status(dw->core_rsts[DW_PCIE_PWR_RST].rstc))
> +		reset_control_assert(dw->core_rsts[DW_PCIE_PWR_RST].rstc);
> +
> +	val = readl(rcar->base + PCIEMSR0);
> +	if (rcar->mode == DW_PCIE_RC_TYPE)
> +		val |= DEVICE_TYPE_RC;
> +	else if (rcar->mode == DW_PCIE_EP_TYPE)
> +		val |= DEVICE_TYPE_EP;
> +	else
> +		return -EINVAL;
> +
> +	if (dw->num_lanes < 4)
> +		val |= BIFUR_MOD_SET_ON;
> +
> +	writel(val, rcar->base + PCIEMSR0);
> +
> +	return reset_control_deassert(dw->core_rsts[DW_PCIE_PWR_RST].rstc);
> +}
> +
> +void rcar_gen4_pcie_common_deinit(struct rcar_gen4_pcie *rcar)
> +{
> +	struct dw_pcie *dw = &rcar->dw;
> +
> +	reset_control_assert(dw->core_rsts[DW_PCIE_PWR_RST].rstc);
> +}
> +
> +int rcar_gen4_pcie_prepare(struct rcar_gen4_pcie *rcar)
> +{
> +	struct device *dev = rcar->dw.dev;
> +	int err;
> +
> +	pm_runtime_enable(dev);
> +	err = pm_runtime_resume_and_get(dev);
> +	if (err < 0) {
> +		dev_err(dev, "Failed to resume/get Runtime PM\n");
> +		pm_runtime_disable(dev);
> +	}
> +
> +	return err;
> +}
> +
> +void rcar_gen4_pcie_unprepare(struct rcar_gen4_pcie *rcar)
> +{
> +	struct device *dev = rcar->dw.dev;
> +
> +	pm_runtime_put(dev);
> +	pm_runtime_disable(dev);
> +}
> +
> +int rcar_gen4_pcie_get_resources(struct rcar_gen4_pcie *rcar)
> +{
> +	/* Renesas-specific registers */
> +	rcar->base = devm_platform_ioremap_resource_byname(rcar->pdev, "app");
> +
> +	return PTR_ERR_OR_ZERO(rcar->base);
> +}
> +
> +static const struct dw_pcie_ops dw_pcie_ops = {
> +	.start_link = rcar_gen4_pcie_start_link,
> +	.stop_link = rcar_gen4_pcie_stop_link,
> +	.link_up = rcar_gen4_pcie_link_up,
> +};
> +
> +struct rcar_gen4_pcie *rcar_gen4_pcie_devm_alloc(struct platform_device *pdev)
> +{
> +	struct device *dev = &pdev->dev;
> +	struct rcar_gen4_pcie *rcar;
> +
> +	rcar = devm_kzalloc(dev, sizeof(*rcar), GFP_KERNEL);
> +	if (!rcar)
> +		return ERR_PTR(-ENOMEM);
> +
> +	rcar->dw.ops = &dw_pcie_ops;
> +	rcar->dw.dev = dev;
> +	rcar->pdev = pdev;
> +	dw_pcie_cap_set(&rcar->dw, EDMA_UNROLL);
> +	dw_pcie_cap_set(&rcar->dw, REQ_RES);
> +	platform_set_drvdata(pdev, rcar);
> +
> +	return rcar;
> +}
> diff --git a/drivers/pci/controller/dwc/pcie-rcar-gen4.h b/drivers/pci/controller/dwc/pcie-rcar-gen4.h
> new file mode 100644
> index 000000000000..7cbb3767c2d4
> --- /dev/null
> +++ b/drivers/pci/controller/dwc/pcie-rcar-gen4.h
> @@ -0,0 +1,44 @@
> +/* SPDX-License-Identifier: GPL-2.0-only */
> +/*
> + * PCIe host/endpoint controller driver for Renesas R-Car Gen4 Series SoCs
> + * Copyright (C) 2022-2023 Renesas Electronics Corporation
> + */
> +
> +#ifndef _PCIE_RCAR_GEN4_H_
> +#define _PCIE_RCAR_GEN4_H_
> +
> +#include <linux/io.h>
> +#include <linux/pci.h>
> +
> +#include "pcie-designware.h"
> +
> +/* Renesas-specific */
> +#define PCIEMSR0		0x0000
> +#define BIFUR_MOD_SET_ON	BIT(0)
> +#define DEVICE_TYPE_EP		0
> +#define DEVICE_TYPE_RC		BIT(4)
> +
> +#define PCIEINTSTS0		0x0084
> +#define PCIEINTSTS0EN		0x0310
> +#define MSI_CTRL_INT		BIT(26)
> +#define SMLH_LINK_UP		BIT(7)
> +#define RDLH_LINK_UP		BIT(6)
> +#define PCIEDMAINTSTSEN		0x0314
> +#define PCIEDMAINTSTSEN_INIT	GENMASK(15, 0)
> +
> +struct rcar_gen4_pcie {
> +	struct dw_pcie dw;
> +	void __iomem *base;
> +	struct platform_device *pdev;
> +	enum dw_pcie_device_mode mode;
> +};
> +#define to_rcar_gen4_pcie(_dw)	container_of(_dw, struct rcar_gen4_pcie, dw)
> +
> +int rcar_gen4_pcie_common_init(struct rcar_gen4_pcie *rcar);
> +void rcar_gen4_pcie_common_deinit(struct rcar_gen4_pcie *rcar);
> +int rcar_gen4_pcie_prepare(struct rcar_gen4_pcie *rcar);
> +void rcar_gen4_pcie_unprepare(struct rcar_gen4_pcie *rcar);
> +int rcar_gen4_pcie_get_resources(struct rcar_gen4_pcie *rcar);
> +struct rcar_gen4_pcie *rcar_gen4_pcie_devm_alloc(struct platform_device *pdev);
> +
> +#endif /* _PCIE_RCAR_GEN4_H_ */
> -- 
> 2.25.1
>