Re: [PATCH 4/7] cxl/mem: Get rid of @cxlm.base

Jonathan Cameron
2021-04-08T17:28:19Z

On Wed, 7 Apr 2021 15:26:22 -0700
Ben Widawsky <ben.widawsky@intel.com> wrote:

> @cxlm.base only existed to support holding the base found in the
> register block mapping code, and pass it along to the register setup
> code. Now that the register setup function has all logic around managing
> the registers, from DVSEC to iomapping up to populating our CXL specific
> information, it is easy to turn the @base values into local variables
> and remove them from our device driver state.
>
> Signed-off-by: Ben Widawsky <ben.widawsky@intel.com>

Patch is basically fine, but I do wonder if you could avoid the
nasty casting in and out of __iomem in the error paths.

It's a common enough idiom though so I'm not htat fussed.

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

> ---
> drivers/cxl/mem.c | 24 +++++++++++-------------
> drivers/cxl/mem.h | 2 --
> 2 files changed, 11 insertions(+), 15 deletions(-)
>
> diff --git a/drivers/cxl/mem.c b/drivers/cxl/mem.c
> index 04b4f7445083..60b95c524c3e 100644
> --- a/drivers/cxl/mem.c
> +++ b/drivers/cxl/mem.c
> @@ -922,11 +922,10 @@ static struct cxl_mem *cxl_mem_create(struct pci_dev *pdev)
> return cxlm;
> }
>
> -static int cxl_mem_map_regblock(struct cxl_mem *cxlm, u32 reg_lo, u32 reg_hi)
> +static void __iomem *cxl_mem_map_regblock(struct cxl_mem *cxlm, u32 reg_lo, u32 reg_hi)
> {
> struct pci_dev *pdev = cxlm->pdev;
> struct device *dev = &pdev->dev;
> - void __iomem *regs;
> u64 offset;
> u8 bar;
> int rc;
> @@ -938,20 +937,18 @@ static int cxl_mem_map_regblock(struct cxl_mem *cxlm, u32 reg_lo, u32 reg_hi)
> if (pci_resource_len(pdev, bar) < offset) {
> dev_err(dev, "BAR%d: %pr: too small (offset: %#llx)\n", bar,
> &pdev->resource[bar], (unsigned long long)offset);
> - return -ENXIO;
> + return (void __iomem *)ERR_PTR(-ENXIO);
> }
>
> rc = pcim_iomap_regions(pdev, BIT(bar), pci_name(pdev));
> if (rc) {
> dev_err(dev, "failed to map registers\n");
> - return rc;
> + return (void __iomem *)ERR_PTR(rc);

The casting is fairly horrible, perhaps just pass in
a void __iomem ** and pass base back through that?

> }
> - regs = pcim_iomap_table(pdev)[bar];
> -
> - cxlm->base = regs + offset;
>
> dev_dbg(dev, "Mapped CXL Memory Device resource\n");
> - return 0;
> +
> + return pcim_iomap_table(pdev)[bar] + offset;
> }
>
> static int cxl_mem_dvsec(struct pci_dev *pdev, int dvsec)
> @@ -993,7 +990,8 @@ static int cxl_mem_setup_regs(struct cxl_mem *cxlm)
> struct pci_dev *pdev = cxlm->pdev;
> struct device *dev = &pdev->dev;
> u32 regloc_size, regblocks;
> - int rc, regloc, i;
> + void __iomem *base;
> + int regloc, i;
>
> regloc = cxl_mem_dvsec(pdev, PCI_DVSEC_ID_CXL_REGLOC_OFFSET);
> if (!regloc) {
> @@ -1019,9 +1017,9 @@ static int cxl_mem_setup_regs(struct cxl_mem *cxlm)
> reg_type = FIELD_GET(CXL_REGLOC_RBI_MASK, reg_lo);
>
> if (reg_type == CXL_REGLOC_RBI_MEMDEV) {
> - rc = cxl_mem_map_regblock(cxlm, reg_lo, reg_hi);
> - if (rc)
> - return rc;
> + base = cxl_mem_map_regblock(cxlm, reg_lo, reg_hi);
> + if (IS_ERR(base))
> + return PTR_ERR(base);
> break;
> }
> }
> @@ -1031,7 +1029,7 @@ static int cxl_mem_setup_regs(struct cxl_mem *cxlm)
> return -ENXIO;
> }
>
> - cxl_setup_device_regs(dev, cxlm->base, &regs->device_regs);
> + cxl_setup_device_regs(dev, base, &regs->device_regs);
>
> if (!regs->status || !regs->mbox || !regs->memdev) {
> dev_err(dev, "registers not found: %s%s%s\n",
> diff --git a/drivers/cxl/mem.h b/drivers/cxl/mem.h
> index 8bad7166adba..bfcfef461b16 100644
> --- a/drivers/cxl/mem.h
> +++ b/drivers/cxl/mem.h
> @@ -49,7 +49,6 @@ struct cxl_memdev {
> /**
> * struct cxl_mem - A CXL memory device
> * @pdev: The PCI device associated with this CXL device.
> - * @base: IO mappings to the device's MMIO
> * @cxlmd: Logical memory device chardev / interface
> * @regs: Parsed register blocks
> * @payload_size: Size of space for payload
> @@ -62,7 +61,6 @@ struct cxl_memdev {
> */
> struct cxl_mem {
> struct pci_dev *pdev;
> - void __iomem *base;
> struct cxl_memdev *cxlmd;
>
> struct cxl_regs regs;