Re: [PATCH V6 06/10] cxl/pci: Find the DOE mailbox which supports CDAT

Ben Widawsky
2022-02-01T18:49:51Z

On 22-01-31 23:19:48, ira.weiny@intel.com wrote:
> From: Ira Weiny <ira.weiny@intel.com>
>
> Memory devices need the CDAT data from the device. This data is read
> from a DOE mailbox which supports the CDAT protocol.
>
> Search the DOE auxiliary devices for the one which supports the CDAT
> protocol. Cache that device to be used for future queries.
>
> Signed-off-by: Ira Weiny <ira.weiny@intel.com>
> ---
> drivers/cxl/cxl.h | 3 +++
> drivers/cxl/cxlmem.h | 2 ++
> drivers/cxl/pci.c | 43 ++++++++++++++++++++++++++++++++++++++++++-
> 3 files changed, 47 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/cxl/cxl.h b/drivers/cxl/cxl.h
> index 962629c5775f..7169101db553 100644
> --- a/drivers/cxl/cxl.h
> +++ b/drivers/cxl/cxl.h
> @@ -90,6 +90,9 @@ static inline int cxl_hdm_decoder_count(u32 cap_hdr)
> #define CXLDEV_MBOX_BG_CMD_STATUS_OFFSET 0x18
> #define CXLDEV_MBOX_PAYLOAD_OFFSET 0x20
>
> +#define CXL_DOE_PROTOCOL_COMPLIANCE 0
> +#define CXL_DOE_PROTOCOL_TABLE_ACCESS 2
> +
> /*
> * Using struct_group() allows for per register-block-type helper routines,
> * without requiring block-type agnostic code to include the prefix.
> diff --git a/drivers/cxl/cxlmem.h b/drivers/cxl/cxlmem.h
> index 5d33ce24fe09..0fefe43951e3 100644
> --- a/drivers/cxl/cxlmem.h
> +++ b/drivers/cxl/cxlmem.h
> @@ -117,6 +117,7 @@ struct cxl_endpoint_dvsec_info {
> * Currently only memory devices are represented.
> *
> * @dev: The device associated with this CXL state
> + * @cdat_doe: Auxiliary DOE device capabile of reading CDAT
> * @regs: Parsed register blocks
> * @cxl_dvsec: Offset to the PCIe device DVSEC
> * @payload_size: Size of space for payload
> @@ -149,6 +150,7 @@ struct cxl_endpoint_dvsec_info {
> struct cxl_dev_state {
> struct device *dev;
>
> + struct pci_doe_dev *cdat_doe;
> struct cxl_regs regs;
> int cxl_dvsec;
>
> diff --git a/drivers/cxl/pci.c b/drivers/cxl/pci.c
> index d4ae79b62a14..dcc55c4efd85 100644
> --- a/drivers/cxl/pci.c
> +++ b/drivers/cxl/pci.c
> @@ -536,12 +536,53 @@ static int cxl_dvsec_ranges(struct cxl_dev_state *cxlds)
> return rc;
> }
>
> +static int cxl_match_cdat_doe_device(struct device *dev, const void *data)
> +{
> + const struct cxl_dev_state *cxlds = data;
> + struct auxiliary_device *adev;
> + struct pci_doe_dev *doe_dev;
> +
> + /* First determine if this auxiliary device belongs to the cxlds */
> + if (cxlds->dev != dev->parent)
> + return 0;

I don't understand auxiliary bus but I'm wondering why it's checking the parent
of the device?

> +
> + adev = to_auxiliary_dev(dev);
> + doe_dev = container_of(adev, struct pci_doe_dev, adev);
> +
> + /* If it is one of ours check for the CDAT protocol */
> + if (pci_doe_supports_prot(doe_dev, PCI_DVSEC_VENDOR_ID_CXL,
> + CXL_DOE_PROTOCOL_TABLE_ACCESS))
> + return 1;
> +
> + return 0;
> +}
> +
> static int cxl_setup_doe_devices(struct cxl_dev_state *cxlds)
> {
> struct device *dev = cxlds->dev;
> struct pci_dev *pdev = to_pci_dev(dev);
> + struct auxiliary_device *adev;
> + int rc;
>
> - return pci_doe_create_doe_devices(pdev);
> + rc = pci_doe_create_doe_devices(pdev);
> + if (rc)
> + return rc;
> +
> + adev = auxiliary_find_device(NULL, cxlds, &cxl_match_cdat_doe_device);
> +
> + if (adev) {
> + struct pci_doe_dev *doe_dev = container_of(adev,
> + struct pci_doe_dev,
> + adev);
> +
> + /*
> + * No reference need be taken. The DOE device lifetime is
> + * longer that the CXL device state lifetime
> + */

You're holding a reference to the adev here. Did you mean to drop it?

> + cxlds->cdat_doe = doe_dev;
> + }
> +
> + return 0;
> }
>
> static int cxl_pci_probe(struct pci_dev *pdev, const struct pci_device_id *id)
> --
> 2.31.1
>