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SubjectRe: [PATCH 11/15] cxl/acpi: Extract the host's component register base address from RCRB
Date


> On Aug 31, 2022, at 1:15 AM, Robert Richter <rrichter@amd.com> wrote:
>
> A downstream port must be connected to a component register block.
> Determine its base address from the RCRB.
>
> The implementation is analog to how cxl_setup_regs() is implemented
> for CXL VH mode. A struct cxl_component_reg_map is filled in, mapped
> and probed.
>
> Signed-off-by: Terry Bowman <terry.bowman@amd.com>
> Signed-off-by: Robert Richter <rrichter@amd.com>
> ---
> drivers/cxl/acpi.c | 80 ++++++++++++++++++++++++++++++++++++++++++++++
> 1 file changed, 80 insertions(+)
>
> diff --git a/drivers/cxl/acpi.c b/drivers/cxl/acpi.c
> index 439df9df2741..88bbd2bb61fc 100644
> --- a/drivers/cxl/acpi.c
> +++ b/drivers/cxl/acpi.c
> @@ -401,12 +401,84 @@ static resource_size_t cxl_get_rcrb(u32 uid)
> return ctx.chbcr;
> }
>
> +static resource_size_t cxl_get_component_reg_phys(resource_size_t rcrb)
> +{
> + resource_size_t component_reg_phys;
> + u32 bar0, bar1;
> + void *addr;
> +
> + /*
> + * RCRB's BAR[0..1] point to component block containing CXL subsystem
> + * component registers.
> + * CXL 8.2.4 - Component Register Layout Definition.
> + *
> + * Also, RCRB accesses must use MMIO readl()/readq() to guarantee
> + * 32/64-bit access.
> + * CXL 8.2.2 - CXL 1.1 Upstream and Downstream Port Subsystem Component
> + * Registers
> + */
> + addr = ioremap(rcrb, PCI_BASE_ADDRESS_0 + SZ_8);
> + bar0 = readl(addr + PCI_BASE_ADDRESS_0);
> + bar1 = readl(addr + PCI_BASE_ADDRESS_1);
> + iounmap(addr);
> +
> + /* sanity check */
> + if (bar0 & (PCI_BASE_ADDRESS_MEM_TYPE_1M | PCI_BASE_ADDRESS_SPACE_IO))
> + return CXL_RESOURCE_NONE;
> +
> + component_reg_phys = bar0 & PCI_BASE_ADDRESS_MEM_MASK;
> + if (bar0 & PCI_BASE_ADDRESS_MEM_TYPE_64)
> + component_reg_phys |= ((u64)bar1) << 32;
> +
> + if (!component_reg_phys)
> + return CXL_RESOURCE_NONE;
> +
> + /*
> + * Must be 8k aligned (size of combined CXL 1.1 Downstream and
> + * Upstream Port RCRBs).
> + */
> + if (component_reg_phys & (SZ_8K - 1))
> + return CXL_RESOURCE_NONE;
> +
> + return component_reg_phys;
> +}
> +
> +static int cxl_setup_component_reg(struct device *parent,
> + resource_size_t component_reg_phys)
> +{
> + struct cxl_component_reg_map comp_map;
> + void __iomem *base;
> +
> + if (component_reg_phys == CXL_RESOURCE_NONE)
> + return -EINVAL;
> +
> + base = ioremap(component_reg_phys, SZ_64K);
> + if (!base) {
> + dev_err(parent, "failed to map registers\n");
> + return -ENOMEM;
> + }
> +
> + cxl_probe_component_regs(parent, base, &comp_map);
> + iounmap(base);
> +
> + if (!comp_map.hdm_decoder.valid) {
> + dev_err(parent, "HDM decoder registers not found\n");
> + return -ENXIO;
> + }
> +
> + dev_dbg(parent, "Set up component registers\n");
> +
> + return 0;
> +}
> +
> static int __init cxl_restricted_host_probe(struct platform_device *pdev)
> {
> struct pci_host_bridge *host = NULL;
> struct acpi_device *adev;
> unsigned long long uid = ~0;
> resource_size_t rcrb;
> + resource_size_t component_reg_phys;
> + int rc;
>
> while ((host = cxl_find_next_rch(host)) != NULL) {
> adev = ACPI_COMPANION(&host->dev);
> @@ -425,10 +497,18 @@ static int __init cxl_restricted_host_probe(struct platform_device *pdev)
>
> dev_dbg(&host->dev, "RCRB found: 0x%08llx\n", (u64)rcrb);
>
> + component_reg_phys = cxl_get_component_reg_phys(rcrb);
> + rc = cxl_setup_component_reg(&host->dev, component_reg_phys);

cxl_setup_component_reg() calls cxl_probe_component_regs() which depends on the existence
of HDM decoder capability register. Such register does not exist when the device is in RCRB
mode, attached to a RCH.

> + if (rc)
> + goto fail;
> +
> dev_info(&host->dev, "host supports CXL\n");
> }
>
> return 0;
> +fail:
> + dev_err(&host->dev, "failed to initialize CXL host: %d\n", rc);
> + return rc;
> }
>
> static struct lock_class_key cxl_root_key;
> --
> 2.30.2
>
>

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