RE: [PATCH v5 11/26] cxl/pci: Early setup RCH dport component registers from RCRB

Dan Williams
2023-06-10T01:44:59Z

Terry Bowman wrote:
> From: Robert Richter <rrichter@amd.com>
>
> CXL RAS capabilities must be enabled and accessible as soon as the CXL
> endpoint is detected in the PCI hierarchy and bound to the cxl_pci
> driver. This needs to be independent of other modules such as cxl_port
> or cxl_mem.
>
> CXL RAS capabilities reside in the Component Registers. For an RCH
> this is determined by probing RCRB which is implemented very late once
> the CXL Memory Device is created.
>
> Change this by moving the RCRB probe to the cxl_pci driver. Do this by
> using a new introduced function cxl_pci_find_port() similar to
> cxl_mem_find_port() to determine the involved dport by the endpoint's
> PCI handle. Plug this into the existing cxl_pci_setup_regs() function
> to setup Component Registers. Probe the RCRB in case the Component
> Registers cannot be located through the CXL Register Locator
> capability.
>
> This unifies code and early sets up the Component Registers at the
> same time for both, VH and RCH mode. Only the cxl_pci driver is
> involved for this. This allows an early mapping of the CXL RAS
> capability registers.
>
> Signed-off-by: Robert Richter <rrichter@amd.com>
> Signed-off-by: Terry Bowman <terry.bowman@amd.com>
> Reviewed-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
> ---
> drivers/cxl/core/port.c | 7 +++++++
> drivers/cxl/cxl.h | 2 ++
> drivers/cxl/mem.c | 10 ----------
> drivers/cxl/pci.c | 37 ++++++++++++++++++++++++++++++++++++-
> 4 files changed, 45 insertions(+), 11 deletions(-)
>
[..]
> diff --git a/drivers/cxl/pci.c b/drivers/cxl/pci.c
> index 945ca0304d68..2975b232fcd1 100644
> --- a/drivers/cxl/pci.c
> +++ b/drivers/cxl/pci.c
> @@ -274,13 +274,48 @@ static int cxl_pci_setup_mailbox(struct cxl_dev_state *cxlds)
> return 0;
> }
>
> +/* Extract RCRB, use same function interface as cxl_find_regblock(). */
> +static int cxl_rcrb_get_comp_regs(struct pci_dev *pdev,
> + enum cxl_regloc_type type,
> + struct cxl_register_map *map)
> +{
> + struct cxl_dport *dport;
> + resource_size_t component_reg_phys;
> +
> + memset(map, 0, sizeof(*map));
> + map->dev = &pdev->dev;
> + map->resource = CXL_RESOURCE_NONE;
> +
> + if (type != CXL_REGLOC_RBI_COMPONENT)
> + return -ENODEV;
> +
> + if (!cxl_pci_find_port(pdev, &dport) || !dport->rch)
> + return -ENXIO;
> +
> + component_reg_phys = cxl_probe_rcrb(&pdev->dev, dport->rcrb.base,
> + NULL, CXL_RCRB_UPSTREAM);
> + if (component_reg_phys == CXL_RESOURCE_NONE)
> + return -ENXIO;
> +
> + map->resource = component_reg_phys;
> + map->reg_type = type;
> + map->max_size = CXL_COMPONENT_REG_BLOCK_SIZE;

One more note, I would prefer a designated initializer for this.