Date:   Mon, 24 Jan 2022 13:45:56 +0100
From:   Patrice CHOTARD <patrice.chotard@...s.st.com>
To:     Alain Volmat <avolmat@...com>, Rob Herring <robh+dt@...nel.org>,
        <linux-pci@...r.kernel.org>
CC:     <linux-arm-kernel@...ts.infradead.org>,
        <linux-kernel@...r.kernel.org>,
        Fabrice Gasnier <fabrice.gasnier@...s.st.com>
Subject: Re: [PATCH RESEND v2 2/5] pci: dwc: pcie-st: Add PCIe driver for STi
 platforms

Hi Alain

Some minor remarks below

You can add my reviewed-by

Thanks
Patrice

On 1/3/22 08:47, Alain Volmat wrote:
> Addition of the PCIe driver (supporting RC) for controllers
> found on some STi platforms such as STiH407, STiH410 or
> STiH418.
> The controller is based on the designware PCIe controller.
> 
> Signed-off-by: Alain Volmat <avolmat@...com>
> ---
> v2: update of the pcie-st driver to add possibility to build as module
>     and remove the __init of the probe
> 
>  drivers/pci/controller/dwc/Kconfig    |  11 +
>  drivers/pci/controller/dwc/Makefile   |   1 +
>  drivers/pci/controller/dwc/pcie-sti.c | 386 ++++++++++++++++++++++++++
>  3 files changed, 398 insertions(+)
>  create mode 100644 drivers/pci/controller/dwc/pcie-sti.c
> 
> diff --git a/drivers/pci/controller/dwc/Kconfig b/drivers/pci/controller/dwc/Kconfig
> index 62ce3abf0f19..232b8ffd54af 100644
> --- a/drivers/pci/controller/dwc/Kconfig
> +++ b/drivers/pci/controller/dwc/Kconfig
> @@ -384,4 +384,15 @@ config PCIE_FU740
>  	  Say Y here if you want PCIe controller support for the SiFive
>  	  FU740.
>  
> +config PCIE_STI
> +	tristate "STMicroelectronics PCIe Controller for STi SoCs"
> +	depends on ARCH_STI || COMPILE_TEST
> +	depends on OF && PCI_MSI_IRQ_DOMAIN
> +	select PCIE_DW_HOST
> +	help
> +	  Enable PCIe controller support on STMicroelectronics STi SoCs.
> +	  This controller is based on Designware hardware and therefore
> +	  the driver re-uses the Designware core functions to implement
> +	  the driver.
> +
>  endmenu
> diff --git a/drivers/pci/controller/dwc/Makefile b/drivers/pci/controller/dwc/Makefile
> index 8ba7b67f5e50..c98fa18714ce 100644
> --- a/drivers/pci/controller/dwc/Makefile
> +++ b/drivers/pci/controller/dwc/Makefile
> @@ -21,6 +21,7 @@ obj-$(CONFIG_PCIE_KEEMBAY) += pcie-keembay.o
>  obj-$(CONFIG_PCIE_KIRIN) += pcie-kirin.o
>  obj-$(CONFIG_PCIE_HISI_STB) += pcie-histb.o
>  obj-$(CONFIG_PCI_MESON) += pci-meson.o
> +obj-$(CONFIG_PCIE_STI) += pcie-sti.o
>  obj-$(CONFIG_PCIE_TEGRA194) += pcie-tegra194.o
>  obj-$(CONFIG_PCIE_UNIPHIER) += pcie-uniphier.o
>  obj-$(CONFIG_PCIE_UNIPHIER_EP) += pcie-uniphier-ep.o
> diff --git a/drivers/pci/controller/dwc/pcie-sti.c b/drivers/pci/controller/dwc/pcie-sti.c
> new file mode 100644
> index 000000000000..61da00a079ac
> --- /dev/null
> +++ b/drivers/pci/controller/dwc/pcie-sti.c
> @@ -0,0 +1,386 @@
> +// SPDX-License-Identifier: GPL-2.0-only
> +/*
> + * Copyright (C) 2021 STMicroelectronics

2022

> + *
> + * STMicroelectronics PCI express Driver for STi SoCs.
> + * ST PCIe IPs are built around a Synopsys IP Core.
> + *
> + * Authors: Fabrice Gasnier <fabrice.gasnier@...s.st.com>
> + *          Alain Volmat <avolmat@...com>
> + */
> +
> +#include <linux/delay.h>
> +#include <linux/interrupt.h>
> +#include <linux/mfd/syscon.h>
> +#include <linux/module.h>
> +#include <linux/of_address.h>
> +#include <linux/of_gpio.h>
> +#include <linux/of_pci.h>
> +#include <linux/of_platform.h>
> +#include <linux/phy/phy.h>
> +#include <linux/regmap.h>
> +#include <linux/reset.h>
> +
> +#include "pcie-designware.h"
> +
> +/* RC_ADDRESS_TRANSLATION Registers */
> +#define TRANSLATION_CONTROL		0x900
> +/* Controls if area is inclusive or exclusive */
> +#define RC_PASS_ADDR_RANGE		BIT(1)
> +
> +/* Base of area reserved for config accesses. Fixed size of 64K. */
> +#define CFG_BASE_ADDRESS		0x92c
> +#define CFG_REGION_SIZE			65536

s/65536/SZ_64K

> +#define CFG_SPACE1_OFFSET		0x1000
> +
> +/* First 4K of config space has this BDF (bus,device,function) */
> +#define FUNC0_BDF_NUM			0x930
> +
> +/* Mem regions */
> +#define IN0_MEM_ADDR_START		0x964
> +#define IN0_MEM_ADDR_LIMIT		0x968
> +#define IN1_MEM_ADDR_START		0x974
> +#define IN1_MEM_ADDR_LIMIT		0x978
> +
> +/* syscfg1 bits */
> +#define PCIE_APP_LTSSM_ENABLE		BIT(2)
> +/* syscfg0 bits */
> +#define PCIE_TYPE_ROOT_COMPLEX		BIT(0)
> +
> +/* st,syscfg offsets */
> +#define SYSCFG0_REG	1
> +#define SYSCFG1_REG	2
> +
> +#define to_st_pcie(x)	dev_get_drvdata((x)->dev)
> +
> +/**
> + * struct st_pcie - private data of the controller
> + * @dw: designware pcie
> + * @syscfg0: PCIe conf register setting root complex, regmap offset
> + * @syscfg1: PCIe conf register for PCIE_APP_LTSSM_ENABLE, regmap offset
> + * @phy: associated pcie phy
> + * @lmi: memory made available to the controller
> + * @regmap: Syscfg registers bank in which PCIe port is configured
> + * @pwr: power control
> + * @rst: reset control
> + * @reset_gpio: optional reset gpio
> + * @config_window_start: start address of 64K config space area
> + */
> +struct st_pcie {
> +	struct dw_pcie *dw;
> +	int syscfg0;
> +	int syscfg1;
> +	struct phy *phy;
> +	struct resource	*lmi;
> +	struct regmap *regmap;
> +	struct reset_control *pwr;
> +	struct reset_control *rst;
> +	struct gpio_desc *reset_gpio;
> +	phys_addr_t config_window_start;
> +};
> +
> +/*
> + * The PCI express core IP expects the following arrangement on it's address
> + * bus (slv_haddr) when driving config cycles.
> + * bus_number		[31:24]
> + * dev_number		[23:19]
> + * func_number		[18:16]
> + * unused		[15:12]
> + * ext_reg_number	[11:8]
> + * reg_number		[7:2]
> + *
> + * Bits [15:12] are unused.
> + *
> + * In the glue logic there is a 64K region of address space that can be
> + * written/read to generate config cycles. The base address of this is
> + * controlled by CFG_BASE_ADDRESS. There are 8 16 bit registers called
> + * FUNC0_BDF_NUM to FUNC8_BDF_NUM. These split the bottom half of the 64K
> + * window into 8 regions at 4K boundaries. These control the bus, device and
> + * function number you are trying to talk to.
> + *
> + * The decision on whether to generate a type 0 or type 1 access is controlled
> + * by bits 15:12 of the address you write to.  If they are zero, then a type 0
> + * is generated, if anything else it will be a type 1. Thus the bottom 4K
> + * region controlled by FUNC0_BDF_NUM can only generate type 0, all the others
> + * can only generate type 1.
> + *
> + * We only use FUNC0_BDF_NUM and FUNC1_BDF_NUM. Which one you use is selected
> + * by bit 12 of the address you write to. The selected register is then used
> + * for the top 16 bits of the slv_haddr to form the bus/dev/func, bit 15:12 are
> + * wired to zero, and bits 11:2 form the address of the register you want to
> + * read in config space.
> + *
> + * We always write FUNC0_BDF_NUM as a 32 bit write. So if we want type 1
> + * accesses we have to shift by 16 so in effect we are writing to FUNC1_BDF_NUM
> + */
> +static inline u32 bdf_num(int bus, int devfn, int is_root_bus)
> +{
> +	return ((bus << 8) | devfn) << (is_root_bus ? 0 : 16);
> +}
> +
> +static void __iomem *st_pcie_other_map_bus(struct pci_bus *bus, unsigned int devfn, int where)
> +{
> +	struct pcie_port *pp = bus->sysdata;
> +	struct dw_pcie *dw = to_dw_pcie_from_pp(pp);
> +	u32 bdf;
> +
> +	bdf = bdf_num(bus->number, devfn, pci_is_root_bus(bus));
> +
> +	/* Set the config packet devfn */
> +	dw_pcie_writel_dbi(dw, FUNC0_BDF_NUM, bdf);
> +	dw_pcie_readl_dbi(dw, FUNC0_BDF_NUM);

Can you add an explaination about this sequence write/read the same register ?

> +
> +	return pp->va_cfg0_base + where + (pci_is_root_bus(bus->parent) ? 0 : CFG_SPACE1_OFFSET);
> +}
> +
> +static struct pci_ops st_child_pcie_ops = {
> +	.map_bus = st_pcie_other_map_bus,
> +	.read = pci_generic_config_read,
> +	.write = pci_generic_config_write,
> +};
> +
> +static void st_pcie_hw_setup(struct dw_pcie *dw)
> +{
> +	struct st_pcie *pcie = to_st_pcie(dw);
> +
> +	/* Set up the config window to the top of the PCI address space */
> +	dw_pcie_writel_dbi(dw, CFG_BASE_ADDRESS, pcie->config_window_start);
> +
> +	/*
> +	 * Open up memory to the PCI controller. We could do slightly
> +	 * better than this and exclude the kernel text segment and bss etc.
> +	 * They are base/limit registers so can be of arbitrary alignment
> +	 * presumably
> +	 */
> +	dw_pcie_writel_dbi(dw, IN0_MEM_ADDR_START, pcie->lmi->start);
> +	dw_pcie_writel_dbi(dw, IN0_MEM_ADDR_LIMIT, pcie->lmi->end);
> +
> +	/* Disable the 2nd region */
> +	dw_pcie_writel_dbi(dw, IN1_MEM_ADDR_START, ~0);
> +	dw_pcie_writel_dbi(dw, IN1_MEM_ADDR_LIMIT, 0);
> +
> +	dw_pcie_writel_dbi(dw, TRANSLATION_CONTROL, RC_PASS_ADDR_RANGE);
> +}
> +
> +static int st_pcie_init(struct pcie_port *pp)
> +{
> +	struct dw_pcie *dw = to_dw_pcie_from_pp(pp);
> +	struct st_pcie *pcie = to_st_pcie(dw);
> +	int ret;
> +
> +	/* Set device type : Root Complex */
> +	ret = regmap_write(pcie->regmap, pcie->syscfg0, PCIE_TYPE_ROOT_COMPLEX);
> +	if (ret < 0) {
> +		dev_err(dw->dev, "unable to set device type\n");
> +		return ret;
> +	}
> +
> +	ret = reset_control_deassert(pcie->pwr);
> +	if (ret) {
> +		dev_err(dw->dev, "unable to bring out of powerdown\n");
> +		return ret;
> +	}
> +
> +	ret = reset_control_deassert(pcie->rst);
> +	if (ret) {
> +		dev_err(dw->dev, "unable to bring out of softreset\n");
> +		return ret;
> +	}
> +
> +	/* let the controller initialize in the proper mode (RC) after reset */
> +	usleep_range(1000, 2000);
> +
> +	return ret;
> +}
> +
> +static int st_pcie_control_ltssm(struct dw_pcie *dw, bool enable)
> +{
> +	struct st_pcie *pcie = to_st_pcie(dw);
> +
> +	return regmap_update_bits(pcie->regmap, pcie->syscfg1, PCIE_APP_LTSSM_ENABLE,
> +				  FIELD_PREP(PCIE_APP_LTSSM_ENABLE, enable));
> +}
> +
> +static int st_pcie_host_init(struct pcie_port *pp)
> +{
> +	struct dw_pcie *dw = to_dw_pcie_from_pp(pp);
> +	struct st_pcie *pcie = to_st_pcie(dw);
> +	int err;
> +
> +	pcie->config_window_start = pp->cfg0_base;
> +
> +	/*
> +	 * "Override" default ops provided by designware driver as STI

s/STI/STi

> +	 * PCIe uses its own translation unit rather than iATU
> +	 */
> +	pp->bridge->child_ops = &st_child_pcie_ops;
> +
> +	/*
> +	 * We have to initialise the PCIe cell on some hardware before we can
> +	 * talk to the phy
> +	 */
> +	err = st_pcie_init(pp);
> +	if (err)
> +		return err;
> +
> +	err = st_pcie_control_ltssm(dw, false);
> +	if (err) {
> +		dev_err(dw->dev, "disable ltssm failed, %d\n", err);
> +		return err;
> +	}
> +
> +	/* Init the associated miphy */
> +	err = phy_init(pcie->phy);
> +	if (err < 0) {
> +		dev_err(dw->dev, "Cannot init PHY: %d\n", err);
> +		return err;
> +	}
> +
> +	return 0;
> +}
> +
> +static int st_pcie_start_link(struct dw_pcie *dw)
> +{
> +	struct st_pcie *pcie = to_st_pcie(dw);
> +	int err;
> +
> +	/* Do all the register poking */
> +	st_pcie_hw_setup(dw);
> +
> +	if (pcie->reset_gpio) {
> +		/* Assert the PERST# signal */
> +		gpiod_set_value(pcie->reset_gpio, 1);
> +
> +		/* PERST# signal must stay asserted for at least 100us (Tperst-clk) */
> +		usleep_range(100, 200);
> +
> +		/* Release PERST# signal */
> +		gpiod_set_value(pcie->reset_gpio, 0);
> +	}
> +
> +	/* Re-enable the link, link training must begin shortly after reset */
> +	err = st_pcie_control_ltssm(dw, true);
> +	if (err) {
> +		dev_err(dw->dev, "enable ltssm failed, %d\n", err);
> +		return err;
> +	}
> +
> +	err = dw_pcie_wait_for_link(dw);
> +	if (err) {
> +		dev_err(dw->dev, "wait for link failed, %d\n", err);
> +		return err;
> +	}
> +
> +	/*
> +	 * PCIe specification states that you should not issue any config
> +	 * requests until 100ms after asserting reset, so we enforce that here
> +	 */
> +	if  (pcie->reset_gpio)
> +		msleep(100);
> +
> +	return 0;
> +}
> +
> +static struct dw_pcie_host_ops st_pcie_host_ops = {
> +	.host_init = st_pcie_host_init,
> +};
> +
> +static const struct dw_pcie_ops dw_pcie_ops = {
> +	.start_link = st_pcie_start_link,
> +};
> +
> +static int st_pcie_probe(struct platform_device *pdev)
> +{
> +	struct st_pcie *pcie;
> +	struct dw_pcie *dw;
> +	struct device_node *np = pdev->dev.of_node;
> +	struct pcie_port *pp;
> +	int ret;
> +
> +	pcie = devm_kzalloc(&pdev->dev, sizeof(*pcie), GFP_KERNEL);
> +	if (!pcie)
> +		return -ENOMEM;
> +
> +	dw = devm_kzalloc(&pdev->dev, sizeof(*dw), GFP_KERNEL);
> +	if (!dw)
> +		return -ENOMEM;
> +	pcie->dw = dw;
> +	dw->dev = &pdev->dev;
> +	dw->ops = &dw_pcie_ops;
> +
> +	pp = &dw->pp;
> +	pp->ops = &st_pcie_host_ops;
> +
> +	/* mem regions */
> +	pcie->lmi = platform_get_resource_byname(pdev, IORESOURCE_MEM, "mem-window");
> +	if (!pcie->lmi)
> +		return -ENXIO;
> +
> +	/* regmap registers for PCIe IP configuration */
> +	pcie->regmap = syscon_regmap_lookup_by_phandle(np, "st,syscfg");
> +	if (IS_ERR(pcie->regmap))
> +		return dev_err_probe(&pdev->dev, PTR_ERR(pcie->regmap),
> +				     "No syscfg phandle specified\n");
> +
> +	ret = of_property_read_u32_index(np, "st,syscfg", SYSCFG0_REG, &pcie->syscfg0);
> +	if (ret) {
> +		dev_err(&pdev->dev, "can't get syscfg0 offset (%d)\n", ret);
> +		return ret;
> +	}
> +
> +	ret = of_property_read_u32_index(np, "st,syscfg", SYSCFG1_REG, &pcie->syscfg1);
> +	if (ret) {
> +		dev_err(&pdev->dev, "can't get syscfg1 offset (%d)\n", ret);
> +		return ret;
> +	}
> +
> +	/* powerdown / resets */
> +	pcie->pwr = devm_reset_control_get_optional(&pdev->dev, "powerdown");
> +	if (IS_ERR(pcie->pwr))
> +		return dev_err_probe(&pdev->dev, PTR_ERR(pcie->pwr),
> +				     "Error getting powerdown reset control\n");
> +
> +	pcie->rst = devm_reset_control_get(&pdev->dev, "softreset");
> +	if (IS_ERR(pcie->rst))
> +		return dev_err_probe(&pdev->dev, PTR_ERR(pcie->rst),
> +				     "Error getting softreset control\n");
> +
> +	/* phy */
> +	pcie->phy = devm_phy_get(&pdev->dev, "pcie");
> +	if (IS_ERR(pcie->phy))
> +		return dev_err_probe(&pdev->dev, PTR_ERR(pcie->phy), "no PHY configured\n");
> +
> +	/* Claim the GPIO for PRST# if available, keep it de-asserted */
> +	pcie->reset_gpio = devm_gpiod_get_optional(&pdev->dev, "reset", GPIOD_OUT_LOW);
> +	if (IS_ERR(pcie->reset_gpio))
> +		return dev_err_probe(&pdev->dev, PTR_ERR(pcie->reset_gpio),
> +				     "Cannot request reset-gpios\n");
> +
> +	platform_set_drvdata(pdev, pcie);
> +
> +	ret = dw_pcie_host_init(pp);
> +	if (ret)
> +		return dev_err_probe(&pdev->dev, ret, "failed to initialize host\n");
> +
> +	return 0;
> +}
> +
> +static const struct of_device_id st_pcie_of_match[] = {
> +	{ .compatible = "st,stih407-pcie", },
> +	{ },
> +};
> +MODULE_DEVICE_TABLE(of, st_pcie_of_match);
> +
> +static struct platform_driver st_pcie_driver __refdata = {
> +	.probe  = st_pcie_probe,
> +	.driver = {
> +		.name = "st-pcie",
> +		.of_match_table = st_pcie_of_match,
> +	},
> +};
> +module_platform_driver(st_pcie_driver);
> +
> +MODULE_AUTHOR("Fabrice Gasnier <fabrice.gasnier@...s.st.com>");
> +MODULE_AUTHOR("Alain Volmat <avolmat@...com>");
> +MODULE_DESCRIPTION("STi PCIe Controller driver");
> +MODULE_LICENSE("GPL v2");

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