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Message-ID: <CAKv+Gu_VBrbra0GZ9gziVh+pcjO34f28t5WHoBTrfYCNAKfnAg@mail.gmail.com>
Date: Wed, 5 Jul 2017 10:36:24 +0100
From: Ard Biesheuvel <ard.biesheuvel@...aro.org>
To: Marc Gonzalez <marc_gonzalez@...madesigns.com>
Cc: Bjorn Helgaas <helgaas@...nel.org>,
Lorenzo Pieralisi <lorenzo.pieralisi@....com>,
Mason <slash.tmp@...e.fr>, Marc Zyngier <marc.zyngier@....com>,
linux-pci <linux-pci@...r.kernel.org>,
Thibaud Cornic <thibaud_cornic@...madesigns.com>,
Liviu Dudau <liviu.dudau@....com>,
LKML <linux-kernel@...r.kernel.org>,
David Laight <david.laight@...lab.com>,
Thomas Gleixner <tglx@...utronix.de>,
Phuong Nguyen <phuong_nguyen@...madesigns.com>,
Robin Murphy <robin.murphy@....com>,
Linux ARM <linux-arm-kernel@...ts.infradead.org>
Subject: Re: [PATCH v5 2/3] PCI: Add tango PCIe host bridge support
On 31 May 2017 at 13:33, Marc Gonzalez <marc_gonzalez@...madesigns.com> wrote:
> This driver is required to work around several hardware bugs
> in the PCIe controller.
>
> NB: Revision 1 does not support legacy interrupts, or IO space.
>
> Signed-off-by: Marc Gonzalez <marc_gonzalez@...madesigns.com>
> ---
> drivers/pci/host/Kconfig | 8 +++
> drivers/pci/host/Makefile | 1 +
> drivers/pci/host/pcie-tango.c | 164 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
> include/linux/pci_ids.h | 2 +
> 4 files changed, 175 insertions(+)
>
[...]
> diff --git a/drivers/pci/host/pcie-tango.c b/drivers/pci/host/pcie-tango.c
> new file mode 100644
> index 000000000000..67aaadcc1c5e
> --- /dev/null
> +++ b/drivers/pci/host/pcie-tango.c
> @@ -0,0 +1,164 @@
> +#include <linux/pci-ecam.h>
> +#include <linux/delay.h>
> +#include <linux/of.h>
> +
> +#define MSI_MAX 256
> +
> +#define SMP8759_MUX 0x48
> +#define SMP8759_TEST_OUT 0x74
> +
> +struct tango_pcie {
> + void __iomem *mux;
> +};
> +
> +/*** HOST BRIDGE SUPPORT ***/
> +
> +static int smp8759_config_read(struct pci_bus *bus,
> + unsigned int devfn, int where, int size, u32 *val)
> +{
> + int ret;
> + struct pci_config_window *cfg = bus->sysdata;
> + struct tango_pcie *pcie = dev_get_drvdata(cfg->parent);
> +
> + /*
> + * QUIRK #1
> + * Reads in configuration space outside devfn 0 return garbage.
> + */
> + if (devfn != 0)
> + return PCIBIOS_FUNC_NOT_SUPPORTED;
> +
Does this mean multi-function devices are not supported? E.g., on my
system I have
-[0000:00]-+-00.0 Advanced Micro Devices, Inc. [AMD] Device 1a00
+-02.0 Advanced Micro Devices, Inc. [AMD] Device 1a01
+-02.1-[01]----00.0 Renesas Technology Corp. uPD720201 USB 3.0
\-02.2-[02]--+-00.0 NVIDIA Corporation GT218 [GeForce 210]
\-00.1 NVIDIA Corporation HD Audio Controller
where the HDMI audio is on devfn 00.1 on bus 2
> + /*
> + * QUIRK #2
> + * Unfortunately, config and mem spaces are muxed.
> + * Linux does not support such a setting, since drivers are free
> + * to access mem space directly, at any time.
> + * Therefore, we can only PRAY that config and mem space accesses
> + * NEVER occur concurrently.
> + */
> + writel_relaxed(1, pcie->mux);
> + ret = pci_generic_config_read(bus, devfn, where, size, val);
> + writel_relaxed(0, pcie->mux);
> +
> + return ret;
> +}
> +
> +static int smp8759_config_write(struct pci_bus *bus,
> + unsigned int devfn, int where, int size, u32 val)
> +{
> + int ret;
> + struct pci_config_window *cfg = bus->sysdata;
> + struct tango_pcie *pcie = dev_get_drvdata(cfg->parent);
> +
> + writel_relaxed(1, pcie->mux);
> + ret = pci_generic_config_write(bus, devfn, where, size, val);
> + writel_relaxed(0, pcie->mux);
> +
> + return ret;
> +}
> +
> +static struct pci_ecam_ops smp8759_ecam_ops = {
> + .bus_shift = 20,
> + .pci_ops = {
> + .map_bus = pci_ecam_map_bus,
> + .read = smp8759_config_read,
> + .write = smp8759_config_write,
> + }
> +};
> +
> +static const struct of_device_id tango_pcie_ids[] = {
> + { .compatible = "sigma,smp8759-pcie" },
> + { /* sentinel */ },
> +};
> +
> +static int tango_check_pcie_link(void __iomem *test_out)
> +{
> + int i;
> +
> + writel_relaxed(16, test_out);
> + for (i = 0; i < 10; ++i) {
> + u32 ltssm_state = readl_relaxed(test_out) >> 8;
> + if ((ltssm_state & 0x1f) == 0xf) /* L0 */
> + return 0;
> + usleep_range(3000, 4000);
> + }
> +
> + return -ENODEV;
> +}
> +
> +static int smp8759_init(struct tango_pcie *pcie, void __iomem *base)
> +{
> + pcie->mux = base + SMP8759_MUX;
> +
> + return tango_check_pcie_link(base + SMP8759_TEST_OUT);
> +}
> +
> +static int tango_pcie_probe(struct platform_device *pdev)
> +{
> + int ret = -EINVAL;
> + void __iomem *base;
> + struct resource *res;
> + struct tango_pcie *pcie;
> + struct device *dev = &pdev->dev;
> +
> + pr_err("MAJOR ISSUE: PCIe config and mem spaces are muxed\n");
> + pr_err("Tainting kernel... Use driver at your own risk\n");
> + add_taint(TAINT_FIRMWARE_WORKAROUND, LOCKDEP_STILL_OK);
> +
> + pcie = devm_kzalloc(dev, sizeof(*pcie), GFP_KERNEL);
> + if (!pcie)
> + return -ENOMEM;
> +
> + platform_set_drvdata(pdev, pcie);
> +
> + res = platform_get_resource(pdev, IORESOURCE_MEM, 1);
> + base = devm_ioremap_resource(&pdev->dev, res);
> + if (IS_ERR(base))
> + return PTR_ERR(base);
> +
> + if (of_device_is_compatible(dev->of_node, "sigma,smp8759-pcie"))
> + ret = smp8759_init(pcie, base);
> +
> + if (ret)
> + return ret;
> +
> + return pci_host_common_probe(pdev, &smp8759_ecam_ops);
> +}
> +
> +static struct platform_driver tango_pcie_driver = {
> + .probe = tango_pcie_probe,
> + .driver = {
> + .name = KBUILD_MODNAME,
> + .of_match_table = tango_pcie_ids,
> + },
> +};
> +
> +builtin_platform_driver(tango_pcie_driver);
> +
> +/*
> + * QUIRK #3
> + * The root complex advertizes the wrong device class.
> + * Header Type 1 is for PCI-to-PCI bridges.
> + */
> +static void tango_fixup_class(struct pci_dev *dev)
> +{
> + dev->class = PCI_CLASS_BRIDGE_PCI << 8;
> +}
> +DECLARE_PCI_FIXUP_EARLY(PCI_VENDOR_ID_SIGMA, 0x24, tango_fixup_class);
> +DECLARE_PCI_FIXUP_EARLY(PCI_VENDOR_ID_SIGMA, 0x28, tango_fixup_class);
> +
> +/*
> + * QUIRK #4
> + * The root complex exposes a "fake" BAR, which is used to filter
> + * bus-to-system accesses. Only accesses within the range defined
> + * by this BAR are forwarded to the host, others are ignored.
> + *
> + * By default, the DMA framework expects an identity mapping,
> + * and DRAM0 is mapped at 0x80000000.
> + */
> +static void tango_fixup_bar(struct pci_dev *dev)
> +{
> + dev->non_compliant_bars = true;
> + pci_write_config_dword(dev, PCI_BASE_ADDRESS_0, 0x80000000);
> +}
> +DECLARE_PCI_FIXUP_EARLY(PCI_VENDOR_ID_SIGMA, 0x24, tango_fixup_bar);
> +DECLARE_PCI_FIXUP_EARLY(PCI_VENDOR_ID_SIGMA, 0x28, tango_fixup_bar);
> diff --git a/include/linux/pci_ids.h b/include/linux/pci_ids.h
> index f020ab4079d3..b577dbe46f8f 100644
> --- a/include/linux/pci_ids.h
> +++ b/include/linux/pci_ids.h
> @@ -1369,6 +1369,8 @@
> #define PCI_DEVICE_ID_TTI_HPT374 0x0008
> #define PCI_DEVICE_ID_TTI_HPT372N 0x0009 /* apparently a 372N variant? */
>
> +#define PCI_VENDOR_ID_SIGMA 0x1105
> +
> #define PCI_VENDOR_ID_VIA 0x1106
> #define PCI_DEVICE_ID_VIA_8763_0 0x0198
> #define PCI_DEVICE_ID_VIA_8380_0 0x0204
> --
> 2.11.0
>
>
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> linux-arm-kernel@...ts.infradead.org
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