On Fri, Nov 19, 2021 at 4:03 PM Ben Widawsky <ben.widawsky@xxxxxxxxx> wrote:
>
> This implements the TODO in cxl_acpi for mapping component registers.
> cxl_acpi becomes the second consumer of CXL register block enumeration
> (cxl_pci being the first). Moving the functionality to cxl_core allows
> both of these drivers to use the functionality. Equally importantly it
> allows cxl_core to use the functionality in the future.
>
> CXL 2.0 root ports are similar to CXL 2.0 Downstream Ports with the main
> distinction being they're a part of the CXL 2.0 host bridge. While
> mapping their component registers is not immediately useful for the CXL
> drivers, the movement of register block enumeration into core is a vital
> step towards HDM decoder programming.
>
> Signed-off-by: Ben Widawsky <ben.widawsky@xxxxxxxxx>
>
> ---
> Changes since RFCv2:
> - Squash commits together (Dan)
> - Reword commit message to account for above.
> ---
> drivers/cxl/acpi.c | 10 ++++++--
> drivers/cxl/core/regs.c | 54 +++++++++++++++++++++++++++++++++++++++++
> drivers/cxl/cxl.h | 4 +++
> drivers/cxl/pci.c | 52 ---------------------------------------
> drivers/cxl/pci.h | 4 +++
> 5 files changed, 70 insertions(+), 54 deletions(-)
>
> diff --git a/drivers/cxl/acpi.c b/drivers/cxl/acpi.c
> index 3163167ecc3a..7cfa8b568013 100644
> --- a/drivers/cxl/acpi.c
> +++ b/drivers/cxl/acpi.c
> @@ -7,6 +7,7 @@
> #include <linux/acpi.h>
> #include <linux/pci.h>
> #include "cxl.h"
> +#include "pci.h"
>
> /* Encode defined in CXL 2.0 8.2.5.12.7 HDM Decoder Control Register */
> #define CFMWS_INTERLEAVE_WAYS(x) (1 << (x)->interleave_ways)
> @@ -134,11 +135,13 @@ static int cxl_parse_cfmws(union acpi_subtable_headers *header, void *arg,
>
> __mock int match_add_root_ports(struct pci_dev *pdev, void *data)
> {
> + resource_size_t creg = CXL_RESOURCE_NONE;
> struct cxl_walk_context *ctx = data;
> struct pci_bus *root_bus = ctx->root;
> struct cxl_port *port = ctx->port;
> int type = pci_pcie_type(pdev);
> struct device *dev = ctx->dev;
> + struct cxl_register_map map;
> u32 lnkcap, port_num;
> int rc;
>
> @@ -152,9 +155,12 @@ __mock int match_add_root_ports(struct pci_dev *pdev, void *data)
> &lnkcap) != PCIBIOS_SUCCESSFUL)
> return 0;
>
> - /* TODO walk DVSEC to find component register base */
> + rc = cxl_find_regblock(pdev, CXL_REGLOC_RBI_COMPONENT, &map);
> + if (!rc)
> + creg = cxl_reg_block(pdev, &map);
A couple comments: the difference between cxl_find_regblock() and
cxl_reg_block() is not obvious from the names. Setting aside why one
is regblock and the other is reg_block I would expect a name like
cxl_regmap_to_base() is easier to read.
It occurs to me that if cxl_find_regblock() failures are optional it
would be nice if cxl_regmap_to_base() returns CXL_RESOURCE_NONE if the
map is not populated. Then this can unconditionally call
cxl_regmap_to_base().
> +
> port_num = FIELD_GET(PCI_EXP_LNKCAP_PN, lnkcap);
> - rc = cxl_add_dport(port, &pdev->dev, port_num, CXL_RESOURCE_NONE);
> + rc = cxl_add_dport(port, &pdev->dev, port_num, creg);
> if (rc) {
> ctx->error = rc;
> return rc;
> diff --git a/drivers/cxl/core/regs.c b/drivers/cxl/core/regs.c
> index e37e23bf4355..41a0245867ea 100644
> --- a/drivers/cxl/core/regs.c
> +++ b/drivers/cxl/core/regs.c
> @@ -5,6 +5,7 @@
> #include <linux/slab.h>
> #include <linux/pci.h>
> #include <cxlmem.h>
> +#include <pci.h>
>
> /**
> * DOC: cxl registers
> @@ -247,3 +248,56 @@ int cxl_map_device_regs(struct pci_dev *pdev,
> return 0;
> }
> EXPORT_SYMBOL_NS_GPL(cxl_map_device_regs, CXL);
> +
> +static void cxl_decode_regblock(u32 reg_lo, u32 reg_hi,
> + struct cxl_register_map *map)
> +{
> + map->block_offset = ((u64)reg_hi << 32) |
> + (reg_lo & CXL_DVSEC_REG_LOCATOR_BLOCK_OFF_LOW_MASK);
> + map->barno = FIELD_GET(CXL_DVSEC_REG_LOCATOR_BIR_MASK, reg_lo);
> + map->reg_type = FIELD_GET(CXL_DVSEC_REG_LOCATOR_BLOCK_ID_MASK, reg_lo);
> +}
> +
> +/**
> + * cxl_find_regblock() - Locate register blocks by type
> + * @pdev: The CXL PCI device to enumerate.
> + * @type: Register Block Indicator id
> + * @map: Enumeration output, clobbered on error
> + *
> + * Return: 0 if register block enumerated, negative error code otherwise
> + *
> + * A CXL DVSEC may additional point one or more register blocks, search
> + * for them by @type.
> + */
> +int cxl_find_regblock(struct pci_dev *pdev, enum cxl_regloc_type type,
> + struct cxl_register_map *map)
> +{
> + u32 regloc_size, regblocks;
> + int regloc, i;
> +
> + regloc = pci_find_dvsec_capability(pdev, PCI_DVSEC_VENDOR_ID_CXL,
> + CXL_DVSEC_REG_LOCATOR);
> + if (!regloc)
> + return -ENXIO;
> +
> + pci_read_config_dword(pdev, regloc + PCI_DVSEC_HEADER1, ®loc_size);
> + regloc_size = FIELD_GET(PCI_DVSEC_HEADER1_LENGTH_MASK, regloc_size);
> +
> + regloc += CXL_DVSEC_REG_LOCATOR_BLOCK1_OFFSET;
> + regblocks = (regloc_size - CXL_DVSEC_REG_LOCATOR_BLOCK1_OFFSET) / 8;
> +
> + for (i = 0; i < regblocks; i++, regloc += 8) {
> + u32 reg_lo, reg_hi;
> +
> + pci_read_config_dword(pdev, regloc, ®_lo);
> + pci_read_config_dword(pdev, regloc + 4, ®_hi);
> +
> + cxl_decode_regblock(reg_lo, reg_hi, map);
> +
> + if (map->reg_type == type)
> + return 0;
> + }
> +
> + return -ENODEV;
> +}
> +EXPORT_SYMBOL_NS_GPL(cxl_find_regblock, CXL);
> diff --git a/drivers/cxl/cxl.h b/drivers/cxl/cxl.h
> index ab4596f0b751..7150a9694f66 100644
> --- a/drivers/cxl/cxl.h
> +++ b/drivers/cxl/cxl.h
> @@ -145,6 +145,10 @@ int cxl_map_device_regs(struct pci_dev *pdev,
> struct cxl_device_regs *regs,
> struct cxl_register_map *map);
>
> +enum cxl_regloc_type;
> +int cxl_find_regblock(struct pci_dev *pdev, enum cxl_regloc_type type,
> + struct cxl_register_map *map);
> +
> #define CXL_RESOURCE_NONE ((resource_size_t) -1)
> #define CXL_TARGET_STRLEN 20
>
> diff --git a/drivers/cxl/pci.c b/drivers/cxl/pci.c
> index 711bf4514480..d2c743a31b0c 100644
> --- a/drivers/cxl/pci.c
> +++ b/drivers/cxl/pci.c
> @@ -433,58 +433,6 @@ static int cxl_map_regs(struct cxl_dev_state *cxlds, struct cxl_register_map *ma
> return 0;
> }
>
> -static void cxl_decode_regblock(u32 reg_lo, u32 reg_hi,
> - struct cxl_register_map *map)
> -{
> - map->block_offset = ((u64)reg_hi << 32) |
> - (reg_lo & CXL_DVSEC_REG_LOCATOR_BLOCK_OFF_LOW_MASK);
> - map->barno = FIELD_GET(CXL_DVSEC_REG_LOCATOR_BIR_MASK, reg_lo);
> - map->reg_type = FIELD_GET(CXL_DVSEC_REG_LOCATOR_BLOCK_ID_MASK, reg_lo);
> -}
> -
> -/**
> - * cxl_find_regblock() - Locate register blocks by type
> - * @pdev: The CXL PCI device to enumerate.
> - * @type: Register Block Indicator id
> - * @map: Enumeration output, clobbered on error
> - *
> - * Return: 0 if register block enumerated, negative error code otherwise
> - *
> - * A CXL DVSEC may point to one or more register blocks, search for them
> - * by @type.
> - */
> -static int cxl_find_regblock(struct pci_dev *pdev, enum cxl_regloc_type type,
> - struct cxl_register_map *map)
> -{
> - u32 regloc_size, regblocks;
> - int regloc, i;
> -
> - regloc = pci_find_dvsec_capability(pdev, PCI_DVSEC_VENDOR_ID_CXL,
> - CXL_DVSEC_REG_LOCATOR);
> - if (!regloc)
> - return -ENXIO;
> -
> - pci_read_config_dword(pdev, regloc + PCI_DVSEC_HEADER1, ®loc_size);
> - regloc_size = FIELD_GET(PCI_DVSEC_HEADER1_LENGTH_MASK, regloc_size);
> -
> - regloc += CXL_DVSEC_REG_LOCATOR_BLOCK1_OFFSET;
> - regblocks = (regloc_size - CXL_DVSEC_REG_LOCATOR_BLOCK1_OFFSET) / 8;
> -
> - for (i = 0; i < regblocks; i++, regloc += 8) {
> - u32 reg_lo, reg_hi;
> -
> - pci_read_config_dword(pdev, regloc, ®_lo);
> - pci_read_config_dword(pdev, regloc + 4, ®_hi);
> -
> - cxl_decode_regblock(reg_lo, reg_hi, map);
> -
> - if (map->reg_type == type)
> - return 0;
> - }
> -
> - return -ENODEV;
> -}
> -
> static int cxl_setup_regs(struct pci_dev *pdev, enum cxl_regloc_type type,
> struct cxl_register_map *map)
> {
> diff --git a/drivers/cxl/pci.h b/drivers/cxl/pci.h
> index 8ae2b4adc59d..a4b506bb37d1 100644
> --- a/drivers/cxl/pci.h
> +++ b/drivers/cxl/pci.h
> @@ -47,4 +47,8 @@ enum cxl_regloc_type {
> CXL_REGLOC_RBI_TYPES
> };
>
> +#define cxl_reg_block(pdev, map) \
> + ((resource_size_t)(pci_resource_start(pdev, (map)->barno) + \
> + (map)->block_offset))
> +
I see no reason for this to be macro. It's also a bug timebomb if
someone in the future does something like:
cxl_reg_block(pdev, map++);
...because the macro references its arguments more than once.
