Re: [RFC PATCH 5/6] PCI: designware: Add SiFive FU740 PCIe host controller driver

[Rob Herring <robh+dt@kernel.org>]

On Tue, Mar 2, 2021 at 4:59 AM Greentime Hu <greentime.hu@sifive.com> wrote:
>
> From: Paul Walmsley <paul.walmsley@sifive.com>
>
> Add driver for the SiFive FU740 PCIe host controller.
> This controller is based on the DesignWare PCIe core.
>
> Co-developed-by: Henry Styles <hes@sifive.com>
> Signed-off-by: Henry Styles <hes@sifive.com>
> Co-developed-by: Erik Danie <erik.danie@sifive.com>
> Signed-off-by: Erik Danie <erik.danie@sifive.com>
> Co-developed-by: Greentime Hu <greentime.hu@sifive.com>
> Signed-off-by: Greentime Hu <greentime.hu@sifive.com>

Your Sob should be last since you are sending the patch.

> Signed-off-by: Paul Walmsley <paul.walmsley@sifive.com>

And Paul's either before yours or first in the list depending on the history.

> ---
>  drivers/pci/controller/dwc/Kconfig      |   9 +
>  drivers/pci/controller/dwc/Makefile     |   1 +
>  drivers/pci/controller/dwc/pcie-fu740.c | 455 ++++++++++++++++++++++++
>  3 files changed, 465 insertions(+)
>  create mode 100644 drivers/pci/controller/dwc/pcie-fu740.c
>
> diff --git a/drivers/pci/controller/dwc/Kconfig b/drivers/pci/controller/dwc/Kconfig
> index 22c5529e9a65..0a37d21ed64e 100644
> --- a/drivers/pci/controller/dwc/Kconfig
> +++ b/drivers/pci/controller/dwc/Kconfig
> @@ -318,4 +318,13 @@ config PCIE_AL
>           required only for DT-based platforms. ACPI platforms with the
>           Annapurna Labs PCIe controller don't need to enable this.
>
> +config PCIE_FU740
> +       bool "SiFive FU740 PCIe host controller"
> +       depends on PCI_MSI_IRQ_DOMAIN
> +       depends on SOC_SIFIVE || COMPILE_TEST
> +       select PCIE_DW_HOST
> +       help
> +         Say Y here if you want PCIe controller support for the SiFive
> +         FU740.
> +
>  endmenu
> diff --git a/drivers/pci/controller/dwc/Makefile b/drivers/pci/controller/dwc/Makefile
> index a751553fa0db..625f6aaeb5b8 100644
> --- a/drivers/pci/controller/dwc/Makefile
> +++ b/drivers/pci/controller/dwc/Makefile
> @@ -5,6 +5,7 @@ obj-$(CONFIG_PCIE_DW_EP) += pcie-designware-ep.o
>  obj-$(CONFIG_PCIE_DW_PLAT) += pcie-designware-plat.o
>  obj-$(CONFIG_PCI_DRA7XX) += pci-dra7xx.o
>  obj-$(CONFIG_PCI_EXYNOS) += pci-exynos.o
> +obj-$(CONFIG_PCIE_FU740) += pcie-fu740.o
>  obj-$(CONFIG_PCI_IMX6) += pci-imx6.o
>  obj-$(CONFIG_PCIE_SPEAR13XX) += pcie-spear13xx.o
>  obj-$(CONFIG_PCI_KEYSTONE) += pci-keystone.o
> diff --git a/drivers/pci/controller/dwc/pcie-fu740.c b/drivers/pci/controller/dwc/pcie-fu740.c
> new file mode 100644
> index 000000000000..6916eea40ea5
> --- /dev/null
> +++ b/drivers/pci/controller/dwc/pcie-fu740.c
> @@ -0,0 +1,455 @@
> +// SPDX-License-Identifier: GPL-2.0
> +/*
> + * FU740 DesignWare PCIe Controller integration
> + * Copyright (C) 2019-2021 SiFive, Inc.
> + * Paul Walmsley
> + * Greentime Hu
> + *
> + * Based in part on the i.MX6 PCIe host controller shim which is:
> + *
> + * Copyright (C) 2013 Kosagi
> + *             https://www.kosagi.com
> + */
> +
> +#include <linux/clk.h>
> +#include <linux/delay.h>
> +#include <linux/gpio.h>
> +#include <linux/kernel.h>
> +#include <linux/mfd/syscon.h>
> +#include <linux/module.h>
> +#include <linux/of_gpio.h>
> +#include <linux/of_device.h>
> +#include <linux/pci.h>
> +#include <linux/platform_device.h>
> +#include <linux/regmap.h>
> +#include <linux/regulator/consumer.h>
> +#include <linux/resource.h>
> +#include <linux/signal.h>
> +#include <linux/types.h>
> +#include <linux/interrupt.h>
> +#include <linux/reset.h>
> +#include <linux/pm_domain.h>
> +#include <linux/pm_runtime.h>
> +
> +#include "pcie-designware.h"
> +
> +#define to_fu740_pcie(x)       dev_get_drvdata((x)->dev)
> +
> +struct fu740_pcie {
> +       struct dw_pcie *pci;
> +       void __iomem *mgmt_base;
> +       int perstn_gpio;
> +       int pwren_gpio;

Use gpio descriptors and the gpiod_* api.

> +       struct clk *pcie_aux;
> +       struct reset_control *rst;
> +};
> +
> +#define SIFIVE_DEVICESRESETREG                 0x28
> +
> +#define PCIEX8MGMT_PERST_N                     0x0
> +#define PCIEX8MGMT_APP_LTSSM_ENABLE            0x10
> +#define PCIEX8MGMT_APP_HOLD_PHY_RST            0x18
> +#define PCIEX8MGMT_DEVICE_TYPE                 0x708
> +#define PCIEX8MGMT_PHY0_CR_PARA_ADDR           0x860
> +#define PCIEX8MGMT_PHY0_CR_PARA_RD_EN          0x870
> +#define PCIEX8MGMT_PHY0_CR_PARA_RD_DATA                0x878
> +#define PCIEX8MGMT_PHY0_CR_PARA_SEL            0x880
> +#define PCIEX8MGMT_PHY0_CR_PARA_WR_DATA                0x888
> +#define PCIEX8MGMT_PHY0_CR_PARA_WR_EN          0x890
> +#define PCIEX8MGMT_PHY0_CR_PARA_ACK            0x898
> +#define PCIEX8MGMT_PHY1_CR_PARA_ADDR           0x8a0
> +#define PCIEX8MGMT_PHY1_CR_PARA_RD_EN          0x8b0
> +#define PCIEX8MGMT_PHY1_CR_PARA_RD_DATA                0x8b8
> +#define PCIEX8MGMT_PHY1_CR_PARA_SEL            0x8c0
> +#define PCIEX8MGMT_PHY1_CR_PARA_WR_DATA                0x8c8
> +#define PCIEX8MGMT_PHY1_CR_PARA_WR_EN          0x8d0
> +#define PCIEX8MGMT_PHY1_CR_PARA_ACK            0x8d8

I tend to think we should split the phy part to a proper phy driver.
Just because the registers happen to be in the same register space
isn't really a good reason to combine them.

> +
> +/* PCIe Port Logic registers (memory-mapped) */
> +#define PL_OFFSET                              0x700

That's all DWC controllers.

> +#define PCIE_PL_GEN2_CTRL_OFF                  (PL_OFFSET + 0x10c)

Also common. Pretty sure there's a define already.

> +#define PCIE_PL_DIRECTED_SPEED_CHANGE_OFF      0x20000
> +
> +#define PCIE_PHY_MAX_RETRY_CNT                 1000
> +
> +static void fu740_pcie_assert_perstn(struct fu740_pcie *afp)
> +{
> +       /* PERST_N GPIO */
> +       if (gpio_is_valid(afp->perstn_gpio))
> +               gpio_direction_output(afp->perstn_gpio, 0);
> +
> +       /* Controller PERST_N */
> +       __raw_writel(0x0, afp->mgmt_base + PCIEX8MGMT_PERST_N);

writel_relaxed is the preferred variant.

> +}
> +
> +static void fu740_pcie_deassert_perstn(struct fu740_pcie *afp)
> +{
> +       /* Controller PERST_N */
> +       __raw_writel(0x1, afp->mgmt_base + PCIEX8MGMT_PERST_N);
> +       /* PERST_N GPIO */
> +       if (gpio_is_valid(afp->perstn_gpio))
> +               gpio_direction_output(afp->perstn_gpio, 1);
> +}
> +
> +static void fu740_pcie_power_on(struct fu740_pcie *afp)
> +{
> +       if (gpio_is_valid(afp->pwren_gpio)) {
> +               gpio_direction_output(afp->pwren_gpio, 1);
> +               mdelay(100);
> +       }
> +}
> +
> +static void fu740_pcie_drive_perstn(struct fu740_pcie *afp)
> +{
> +       fu740_pcie_assert_perstn(afp);
> +       fu740_pcie_power_on(afp);
> +       fu740_pcie_deassert_perstn(afp);
> +}
> +
> +static void fu740_phyregreadwrite(const uint8_t phy, const uint8_t write,
> +                               const uint16_t addr,
> +                               const uint16_t wrdata, uint16_t *rddata,
> +                               struct fu740_pcie *afp)

I think you should split this into separate read and write functions.

> +{
> +       unsigned char ack = 0;
> +       unsigned int cnt = 0;
> +       struct device *dev = afp->pci->dev;
> +
> +       /* setup */
> +       __raw_writel(addr,
> +                    afp->mgmt_base +
> +                    (phy ? PCIEX8MGMT_PHY1_CR_PARA_ADDR :
> +                     PCIEX8MGMT_PHY0_CR_PARA_ADDR));
> +       if (write)
> +               __raw_writel(wrdata,
> +                            afp->mgmt_base +
> +                            (phy ? PCIEX8MGMT_PHY1_CR_PARA_WR_DATA :
> +                             PCIEX8MGMT_PHY0_CR_PARA_WR_DATA));
> +       if (write)
> +               __raw_writel(1,
> +                            afp->mgmt_base +
> +                            (phy ? PCIEX8MGMT_PHY1_CR_PARA_WR_EN :
> +                             PCIEX8MGMT_PHY0_CR_PARA_WR_EN));
> +       else
> +               __raw_writel(1,
> +                            afp->mgmt_base +
> +                            (phy ? PCIEX8MGMT_PHY1_CR_PARA_RD_EN :
> +                             PCIEX8MGMT_PHY0_CR_PARA_RD_EN));
> +
> +       /* wait for wait_idle */
> +       do {
> +               if (__raw_readl
> +                   (afp->mgmt_base +
> +                    (phy ? PCIEX8MGMT_PHY1_CR_PARA_ACK :
> +                     PCIEX8MGMT_PHY0_CR_PARA_ACK))) {
> +                       ack = 1;
> +                       if (!write)
> +                               __raw_readl(afp->mgmt_base +
> +                                           (phy ?
> +                                            PCIEX8MGMT_PHY1_CR_PARA_RD_DATA :
> +                                            PCIEX8MGMT_PHY0_CR_PARA_RD_DATA));
> +               }
> +       } while (!ack);
> +
> +       /* clear */
> +       if (write)
> +               __raw_writel(0,
> +                            afp->mgmt_base +
> +                            (phy ? PCIEX8MGMT_PHY1_CR_PARA_WR_EN :
> +                             PCIEX8MGMT_PHY0_CR_PARA_WR_EN));
> +       else
> +               __raw_writel(0,
> +                            afp->mgmt_base +
> +                            (phy ? PCIEX8MGMT_PHY1_CR_PARA_RD_EN :
> +                             PCIEX8MGMT_PHY0_CR_PARA_RD_EN));
> +
> +       /* wait for ~wait_idle */
> +       while (__raw_readl
> +              (afp->mgmt_base +
> +               (phy ? PCIEX8MGMT_PHY1_CR_PARA_ACK :
> +                PCIEX8MGMT_PHY0_CR_PARA_ACK))) {
> +               cpu_relax();
> +               cnt++;
> +               if (cnt > PCIE_PHY_MAX_RETRY_CNT) {
> +                       dev_err(dev, "PCIE phy doesn't enter idle state.\n");
> +                       break;
> +               }
> +       }

We have helpers for this kind of loop.

> +}
> +
> +static void fu740_pcie_init_phy(struct fu740_pcie *afp)
> +{
> +       int lane;
> +
> +       /* enable phy cr_para_sel interfaces */
> +       __raw_writel(0x1, afp->mgmt_base + PCIEX8MGMT_PHY0_CR_PARA_SEL);
> +       __raw_writel(0x1, afp->mgmt_base + PCIEX8MGMT_PHY1_CR_PARA_SEL);
> +
> +       /* wait 10 cr_para cycles */
> +       msleep(1);
> +
> +       /* set PHY AC termination mode */
> +       for (lane = 0; lane < 4; lane++) {
> +               fu740_phyregreadwrite(0, 1,
> +                                    0x1008 + (0x100 * lane),
> +                                    0x0e21, NULL, afp);
> +               fu740_phyregreadwrite(1, 1,
> +                                    0x1008 + (0x100 * lane),
> +                                    0x0e21, NULL, afp);
> +       }
> +
> +}
> +
> +static void fu740_pcie_ltssm_enable(struct device *dev)
> +{
> +       struct fu740_pcie *afp = dev_get_drvdata(dev);
> +
> +       /* Enable LTSSM */
> +       __raw_writel(0x1, afp->mgmt_base + PCIEX8MGMT_APP_LTSSM_ENABLE);
> +}
> +
> +static int fu740_pcie_start_link(struct dw_pcie *pci)
> +{
> +       struct device *dev = pci->dev;
> +       u8 offset = dw_pcie_find_capability(pci, PCI_CAP_ID_EXP);
> +       u32 tmp;
> +       int ret;
> +
> +       /*
> +        * Force Gen1 operation when starting the link.  In case the link is
> +        * started in Gen2 mode, there is a possibility the devices on the
> +        * bus will not be detected at all.  This happens with PCIe switches.
> +        */
> +       dw_pcie_dbi_ro_wr_en(pci);
> +       tmp = dw_pcie_readl_dbi(pci, offset + PCI_EXP_LNKCAP);
> +       tmp &= ~PCI_EXP_LNKCAP_SLS;
> +       tmp |= PCI_EXP_LNKCAP_SLS_2_5GB;
> +       dw_pcie_writel_dbi(pci, offset + PCI_EXP_LNKCAP, tmp);
> +       dw_pcie_dbi_ro_wr_dis(pci);
> +
> +       /* Start LTSSM. */
> +       fu740_pcie_ltssm_enable(dev);
> +
> +       ret = dw_pcie_wait_for_link(pci);
> +       if (ret)
> +               goto err_reset_phy;
> +
> +       /* Now set it to operate in Gen3 */
> +       dw_pcie_dbi_ro_wr_en(pci);
> +       tmp = dw_pcie_readl_dbi(pci, offset + PCI_EXP_LNKCAP);
> +       tmp &= ~PCI_EXP_LNKCAP_SLS;
> +       tmp |= PCI_EXP_LNKCAP_SLS_8_0GB;

You don't support slower speeds?

We have some common DWC handling of this too, that doesn't work?

> +       dw_pcie_writel_dbi(pci, offset + PCI_EXP_LNKCAP, tmp);
> +       /* Enable DIRECTED SPEED CHANGE bit of GEN2_CTRL_OFF register */
> +       tmp = dw_pcie_readl_dbi(pci, PCIE_PL_GEN2_CTRL_OFF);
> +       tmp |= PCIE_PL_DIRECTED_SPEED_CHANGE_OFF;
> +       dw_pcie_writel_dbi(pci, PCIE_PL_GEN2_CTRL_OFF, tmp);
> +       dw_pcie_dbi_ro_wr_dis(pci);
> +
> +       ret = dw_pcie_wait_for_link(pci);
> +       if (ret)
> +               goto err_reset_phy;
> +
> +       /*
> +        * Reenable DIRECTED SPEED CHANGE.
> +        *
> +        * You need to set this bit after each speed change, but after
> +        * reaching G1, setting it once doesn't seem to work (it reaches G3
> +        * equalization states and then times out, falls back to G1). But
> +        * If after that, you set it again, it then reaches G3 perfectly
> +        * fine.
> +        */
> +       dw_pcie_dbi_ro_wr_en(pci);
> +       tmp = dw_pcie_readl_dbi(pci, PCIE_PL_GEN2_CTRL_OFF);
> +       tmp |= PCIE_PL_DIRECTED_SPEED_CHANGE_OFF;
> +       dw_pcie_writel_dbi(pci, PCIE_PL_GEN2_CTRL_OFF, tmp);
> +       dw_pcie_dbi_ro_wr_dis(pci);
> +
> +       ret = dw_pcie_wait_for_link(pci);

The DWC core does this after start_link() now.

> +       if (ret)
> +               goto err_reset_phy;
> +
> +       tmp = dw_pcie_readw_dbi(pci, offset + PCI_EXP_LNKSTA);
> +       dev_info(dev, "Link up, Gen%i\n", tmp & PCI_EXP_LNKSTA_CLS);

If we want this, it should be common.

> +       return 0;
> +
> + err_reset_phy:
> +       dev_err(dev, "Failed to bring link up!\n"
> +               "PHY DEBUG_R0=0x%08x DEBUG_R1=0x%08x\n",
> +               dw_pcie_readl_dbi(pci, PCIE_PORT_DEBUG0),
> +               dw_pcie_readl_dbi(pci, PCIE_PORT_DEBUG1));
> +       return ret;
> +}
> +
> +static int fu740_pcie_host_init(struct pcie_port *pp)
> +{
> +       struct dw_pcie *pci = to_dw_pcie_from_pp(pp);
> +       struct fu740_pcie *afp = to_fu740_pcie(pci);
> +       struct device *dev = pci->dev;
> +       int ret = 0;
> +
> +       /* power on reset */
> +       fu740_pcie_drive_perstn(afp);
> +
> +       /* enable pcieauxclk */
> +       ret = clk_prepare_enable(afp->pcie_aux);
> +       if (ret)
> +               dev_err(dev, "unable to enable pcie_aux clock\n");
> +
> +       /*
> +        * assert hold_phy_rst (hold the controller LTSSM in reset after
> +        * power_up_rst_n
> +        * for register programming with cr_para)
> +        */
> +       __raw_writel(0x1, afp->mgmt_base + PCIEX8MGMT_APP_HOLD_PHY_RST);
> +
> +       /* deassert power_up_rst_n */
> +       ret = reset_control_deassert(afp->rst);
> +       if (ret)
> +               dev_err(dev, "unable to deassert pcie_power_up_rst_n\n");
> +
> +       fu740_pcie_init_phy(afp);
> +
> +       /* disable pcieauxclk */
> +       clk_disable_unprepare(afp->pcie_aux);
> +       /* clear hold_phy_rst */
> +       __raw_writel(0x0, afp->mgmt_base + PCIEX8MGMT_APP_HOLD_PHY_RST);
> +       /* enable pcieauxclk */
> +       ret = clk_prepare_enable(afp->pcie_aux);
> +       /* set RC mode */
> +       __raw_writel(0x4, afp->mgmt_base + PCIEX8MGMT_DEVICE_TYPE);
> +
> +       return 0;
> +}
> +
> +static const struct dw_pcie_host_ops fu740_pcie_host_ops = {
> +       .host_init = fu740_pcie_host_init,
> +};
> +
> +static const struct dw_pcie_ops dw_pcie_ops = {
> +       .start_link = fu740_pcie_start_link,
> +};
> +
> +static const struct dev_pm_ops fu740_pcie_pm_ops = {
> +       SET_NOIRQ_SYSTEM_SLEEP_PM_OPS(fu740_pcie_suspend_noirq,
> +                                     fu740_pcie_resume_noirq)
> +};
> +
> +static int fu740_pcie_probe(struct platform_device *pdev)
> +{
> +       struct device *dev = &pdev->dev;
> +       struct dw_pcie *pci;
> +       struct fu740_pcie *afp;
> +       struct resource *mgmt_res;
> +       struct device_node *node = dev->of_node;
> +       int ret;
> +       u16 val;
> +
> +       afp = devm_kzalloc(dev, sizeof(*afp), GFP_KERNEL);
> +       if (!afp)
> +               return -ENOMEM;
> +
> +       pci = devm_kzalloc(dev, sizeof(*pci), GFP_KERNEL);

Embed dw_pcie in fu740_pcie and do 1 alloc.

> +       if (!pci)
> +               return -ENOMEM;
> +
> +       pci->dev = dev;
> +       pci->ops = &dw_pcie_ops;
> +       pci->pp.ops = &fu740_pcie_host_ops;
> +
> +       afp->pci = pci;
> +
> +       mgmt_res = platform_get_resource_byname(pdev, IORESOURCE_MEM, "mgmt");
> +       if (!mgmt_res) {
> +               dev_warn(dev, "missing required mgmt address range");
> +               return -ENOENT;
> +       }
> +       afp->mgmt_base = devm_ioremap_resource(dev, mgmt_res);

Use devm_platform_ioremap_resource_byname


> +       if (IS_ERR(afp->mgmt_base))
> +               return PTR_ERR(afp->mgmt_base);
> +
> +       /* Fetch GPIOs */
> +       afp->perstn_gpio = of_get_named_gpio(node, "perstn-gpios", 0);
> +       if (gpio_is_valid(afp->perstn_gpio)) {
> +               ret = devm_gpio_request_one(dev, afp->perstn_gpio,
> +                                           GPIOF_OUT_INIT_LOW, "perstn-gpios");
> +               if (ret) {
> +                       dev_err(dev, "unable to get perstn gpio\n");
> +                       return ret;
> +               }
> +       } else if (afp->perstn_gpio == -EPROBE_DEFER) {
> +               dev_err(dev, "perst-gpios EPROBE_DEFER\n");
> +               return afp->perstn_gpio;
> +       }

GPIOs are optional? That's not what the binding says.

> +
> +       afp->pwren_gpio = of_get_named_gpio(node, "pwren-gpios", 0);
> +       if (gpio_is_valid(afp->pwren_gpio)) {
> +               ret = devm_gpio_request_one(dev, afp->pwren_gpio,
> +                                           GPIOF_OUT_INIT_LOW, "pwren-gpios");
> +               if (ret) {
> +                       dev_err(dev, "unable to get pwren gpio\n");
> +                       return ret;
> +               }
> +       } else if (afp->pwren_gpio == -EPROBE_DEFER) {
> +               dev_err(dev, "pwren-gpios EPROBE_DEFER\n");
> +               return afp->pwren_gpio;
> +       }
> +
> +       /* Fetch clocks */
> +       afp->pcie_aux = devm_clk_get(dev, "pcie_aux");
> +       if (IS_ERR(afp->pcie_aux))
> +               return dev_err_probe(dev, PTR_ERR(afp->pcie_aux),
> +                                            "pcie_aux clock source missing or invalid\n");
> +
> +       /* Fetch reset */
> +       afp->rst = devm_reset_control_get(dev, NULL);
> +       if (IS_ERR(afp->rst))
> +               return dev_err_probe(dev, PTR_ERR(afp->rst), "unable to get reset\n");
> +
> +       platform_set_drvdata(pdev, afp);
> +
> +       ret = dw_pcie_host_init(&pci->pp);
> +       if (ret < 0)
> +               return ret;
> +
> +       if (pci_msi_enabled()) {
> +               u8 offset = dw_pcie_find_capability(pci, PCI_CAP_ID_MSI);
> +
> +               val = dw_pcie_readw_dbi(pci, offset + PCI_MSI_FLAGS);
> +               val |= PCI_MSI_FLAGS_ENABLE;
> +               dw_pcie_writew_dbi(pci, offset + PCI_MSI_FLAGS, val);

Are you sure this is needed? It's suspect that only i.MX6 needs it.

> +       }
> +
> +       return 0;
> +}
> +
> +static void fu740_pcie_shutdown(struct platform_device *pdev)
> +{
> +       struct fu740_pcie *afp = platform_get_drvdata(pdev);
> +
> +       /* bring down link, so bootloader gets clean state in case of reboot */
> +       fu740_pcie_assert_perstn(afp);
> +}
> +
> +static const struct of_device_id fu740_pcie_of_match[] = {
> +       {.compatible = "sifive,fu740-pcie"},
> +       {},
> +};
> +
> +static struct platform_driver fu740_pcie_driver = {
> +       .driver = {
> +                  .name = "fu740-pcie",
> +                  .of_match_table = fu740_pcie_of_match,
> +                  .suppress_bind_attrs = true,
> +                  .pm = &fu740_pcie_pm_ops,
> +                  },
> +       .probe = fu740_pcie_probe,
> +       .shutdown = fu740_pcie_shutdown,
> +};
> +
> +static int __init fu740_pcie_init(void)
> +{
> +       return platform_driver_register(&fu740_pcie_driver);
> +}
> +
> +device_initcall(fu740_pcie_init);

Needs to be early? Why?