Re: [PATCH 03/23] cxl/pci: Extract device status check

[Jonathan Cameron <Jonathan.Cameron@Huawei.com>]

On Fri, 19 Nov 2021 16:02:30 -0800
Ben Widawsky <ben.widawsky@intel.com> wrote:

> The Memory Device Status register is inspected in the same way for at
> least two flows in the CXL Type 3 Memory Device Software Guide
> (Revision: 1.0): 2.13.9 Device discovery and mailbox ready sequence,
> and 2.13.10 Media ready sequence. Extract this common functionality for
> use by both.
> 
> Signed-off-by: Ben Widawsky <ben.widawsky@intel.com>

Reviewed-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>

> ---
> This patch did not exist in RFCv2
> ---
>  drivers/cxl/pci.c | 33 +++++++++++++++++++++++++--------
>  1 file changed, 25 insertions(+), 8 deletions(-)
> 
> diff --git a/drivers/cxl/pci.c b/drivers/cxl/pci.c
> index a6ea9811a05b..6c8d09fb3a17 100644
> --- a/drivers/cxl/pci.c
> +++ b/drivers/cxl/pci.c
> @@ -182,6 +182,27 @@ static int __cxl_pci_mbox_send_cmd(struct cxl_dev_state *cxlds,
>  	return 0;
>  }
>  
> +/*
> + * Implements roughly the bottom half of Figure 42 of the CXL Type 3 Memory
> + * Device Software Guide
> + */
> +static int check_device_status(struct cxl_dev_state *cxlds)
> +{
> +	const u64 md_status = readq(cxlds->regs.memdev + CXLMDEV_STATUS_OFFSET);
> +
> +	if (md_status & CXLMDEV_DEV_FATAL) {
> +		dev_err(cxlds->dev, "Fatal: replace device\n");
> +		return -EIO;
> +	}
> +
> +	if (md_status & CXLMDEV_FW_HALT) {
> +		dev_err(cxlds->dev, "FWHalt: reset or replace device\n");
> +		return -EBUSY;
> +	}
> +
> +	return 0;
> +}
> +
>  /**
>   * cxl_pci_mbox_get() - Acquire exclusive access to the mailbox.
>   * @cxlds: The device state to gain access to.
> @@ -231,17 +252,13 @@ static int cxl_pci_mbox_get(struct cxl_dev_state *cxlds)
>  	 * Hardware shouldn't allow a ready status but also have failure bits
>  	 * set. Spit out an error, this should be a bug report
>  	 */
> -	rc = -EFAULT;
> -	if (md_status & CXLMDEV_DEV_FATAL) {
> -		dev_err(dev, "mbox: reported ready, but fatal\n");
> +	rc = check_device_status(cxlds);
> +	if (rc)
>  		goto out;
> -	}
> -	if (md_status & CXLMDEV_FW_HALT) {
> -		dev_err(dev, "mbox: reported ready, but halted\n");
> -		goto out;
> -	}
> +
>  	if (CXLMDEV_RESET_NEEDED(md_status)) {
>  		dev_err(dev, "mbox: reported ready, but reset needed\n");
> +		rc = -EFAULT;
>  		goto out;
>  	}
>