| Message ID | 2ecb33dfee5dc05efc05de0731b0cb77bc246f54.1612269537.git.gustavo.pimentel@synopsys.com (mailing list archive) |
|---|---|
| State | Superseded |
| Headers | show |
| Series | dmaengine: dw-edma: HDMA support | expand |
On Tue, Feb 02, 2021 at 01:40:18PM +0100, Gustavo Pimentel wrote: > /** > + * pci_find_vsec_capability - Find a vendor-specific extended capability > + * @dev: PCI device to query > + * @cap: vendor-specific capability ID code > + * > + * Returns the address of the vendor-specific structure that matches the > + * requested capability ID code within the device's PCI configuration space > + * or 0 if it does not find a match. > + */ > +u16 pci_find_vsec_capability(struct pci_dev *dev, int vsec_cap_id) > +{ As the name implies, the capability is "vendor-specific", so it is perfectly possible that two vendors use the same VSEC ID for different things. To make sure you're looking for the right capability, you need to pass a u16 vendor into this function and bail out if dev->vendor is different. > + u16 vsec; > + u32 header; > + > + vsec = pci_find_ext_capability(dev, PCI_EXT_CAP_ID_VNDR); > + while (vsec) { > + if (pci_read_config_dword(dev, vsec + PCI_VSEC_HDR, > + &header) == PCIBIOS_SUCCESSFUL && > + PCI_VSEC_CAP_ID(header) == vsec_cap_id) > + return vsec; > + > + vsec = pci_find_next_ext_capability(dev, vsec, > + PCI_EXT_CAP_ID_VNDR); > + } FWIW, a more succinct implementation would be: while ((vsec = pci_find_next_ext_capability(...))) { ... } See set_pcie_thunderbolt() in drivers/pci/probe.c for an example. Please consider refactoring that function to use your new helper. Thanks, Lukas
Hi Lukas, On Tue, Feb 2, 2021 at 18:8:55, Lukas Wunner <lukas@wunner.de> wrote: > On Tue, Feb 02, 2021 at 01:40:18PM +0100, Gustavo Pimentel wrote: > > /** > > + * pci_find_vsec_capability - Find a vendor-specific extended capability > > + * @dev: PCI device to query > > + * @cap: vendor-specific capability ID code > > + * > > + * Returns the address of the vendor-specific structure that matches the > > + * requested capability ID code within the device's PCI configuration space > > + * or 0 if it does not find a match. > > + */ > > +u16 pci_find_vsec_capability(struct pci_dev *dev, int vsec_cap_id) > > +{ > > As the name implies, the capability is "vendor-specific", so it is perfectly > possible that two vendors use the same VSEC ID for different things. > > To make sure you're looking for the right capability, you need to pass > a u16 vendor into this function and bail out if dev->vendor is different. This function will be called by the driver that will pass the correct device which will be already pointing to the config space associated with the endpoint for instance. Because the driver is already attached to the endpoint through the vendor ID and device ID specified, there is no need to do that validation, it will be redundant. > > > > + u16 vsec; > > + u32 header; > > + > > + vsec = pci_find_ext_capability(dev, PCI_EXT_CAP_ID_VNDR); > > + while (vsec) { > > + if (pci_read_config_dword(dev, vsec + PCI_VSEC_HDR, > > + &header) == PCIBIOS_SUCCESSFUL && > > + PCI_VSEC_CAP_ID(header) == vsec_cap_id) > > + return vsec; > > + > > + vsec = pci_find_next_ext_capability(dev, vsec, > > + PCI_EXT_CAP_ID_VNDR); > > + } > > FWIW, a more succinct implementation would be: > > while ((vsec = pci_find_next_ext_capability(...))) { ... } > > See set_pcie_thunderbolt() in drivers/pci/probe.c for an example. > Please consider refactoring that function to use your new helper. That looks more clean. I will do it. Thanks! > > Thanks, > > Lukas
On Wed, Feb 03, 2021 at 01:54:49AM +0000, Gustavo Pimentel wrote: > On Tue, Feb 2, 2021 at 18:8:55, Lukas Wunner <lukas@wunner.de> wrote: > > As the name implies, the capability is "vendor-specific", so it is > > perfectly possible that two vendors use the same VSEC ID for different > > things. > > > > To make sure you're looking for the right capability, you need to pass > > a u16 vendor into this function and bail out if dev->vendor is different. > > This function will be called by the driver that will pass the correct > device which will be already pointing to the config space associated with > the endpoint for instance. Because the driver is already attached to the > endpoint through the vendor ID and device ID specified, there is no need > to do that validation, it will be redundant. Okay. Please amend the kernel-doc to make it explicit that it's the caller's responsibility to check the vendor ID. Thanks, Lukas
On Wed, Feb 3, 2021 at 7:51:3, Lukas Wunner <lukas@wunner.de> wrote: > On Wed, Feb 03, 2021 at 01:54:49AM +0000, Gustavo Pimentel wrote: > > On Tue, Feb 2, 2021 at 18:8:55, Lukas Wunner <lukas@wunner.de> wrote: > > > As the name implies, the capability is "vendor-specific", so it is > > > perfectly possible that two vendors use the same VSEC ID for different > > > things. > > > > > > To make sure you're looking for the right capability, you need to pass > > > a u16 vendor into this function and bail out if dev->vendor is different. > > > > This function will be called by the driver that will pass the correct > > device which will be already pointing to the config space associated with > > the endpoint for instance. Because the driver is already attached to the > > endpoint through the vendor ID and device ID specified, there is no need > > to do that validation, it will be redundant. > > Okay. Please amend the kernel-doc to make it explicit that it's the > caller's responsibility to check the vendor ID. I don't think that would be necessary, as I said, the 'struct pci_dev *' already points exclusively for the device' config space, which contains all the capabilities for that particular device by his turn will be attached to a specific driver by the Vendor and Device IDs to a specific driver, that will know, firstly search for the specific device vendor ID, and then secondly how to decode it, and thirdly to do something with it. > > Thanks, > > Lukas
On Wed, Feb 03, 2021 at 09:11:03AM +0000, Gustavo Pimentel wrote: > On Wed, Feb 3, 2021 at 7:51:3, Lukas Wunner <lukas@wunner.de> wrote: > > On Wed, Feb 03, 2021 at 01:54:49AM +0000, Gustavo Pimentel wrote: > > > On Tue, Feb 2, 2021 at 18:8:55, Lukas Wunner <lukas@wunner.de> wrote: > > > > As the name implies, the capability is "vendor-specific", so it is > > > > perfectly possible that two vendors use the same VSEC ID for different > > > > things. > > > > > > > > To make sure you're looking for the right capability, you need to pass > > > > a u16 vendor into this function and bail out if dev->vendor is > > > > different. > > > > > > This function will be called by the driver that will pass the correct > > > device which will be already pointing to the config space associated with > > > the endpoint for instance. Because the driver is already attached to the > > > endpoint through the vendor ID and device ID specified, there is no need > > > to do that validation, it will be redundant. > > > > Okay. Please amend the kernel-doc to make it explicit that it's the > > caller's responsibility to check the vendor ID. > > I don't think that would be necessary, as I said, the 'struct pci_dev *' > already points exclusively for the device' config space, which contains > all the capabilities for that particular device by his turn will be > attached to a specific driver by the Vendor and Device IDs to a specific > driver, that will know, firstly search for the specific device vendor ID, > and then secondly how to decode it, and thirdly to do something with it. The helper you're adding may not only be called from drivers but also from generic PCI code (such as set_pcie_thunderbolt()). In that case the vendor ID is arbitrary. Also, it doesn't *hurt* documenting this requirement, does it? Thanks, Lukas
On Wed, Feb 3, 2021 at 9:36:54, Lukas Wunner <lukas@wunner.de> wrote: > On Wed, Feb 03, 2021 at 09:11:03AM +0000, Gustavo Pimentel wrote: > > On Wed, Feb 3, 2021 at 7:51:3, Lukas Wunner <lukas@wunner.de> wrote: > > > On Wed, Feb 03, 2021 at 01:54:49AM +0000, Gustavo Pimentel wrote: > > > > On Tue, Feb 2, 2021 at 18:8:55, Lukas Wunner <lukas@wunner.de> wrote: > > > > > As the name implies, the capability is "vendor-specific", so it is > > > > > perfectly possible that two vendors use the same VSEC ID for different > > > > > things. > > > > > > > > > > To make sure you're looking for the right capability, you need to pass > > > > > a u16 vendor into this function and bail out if dev->vendor is > > > > > different. > > > > > > > > This function will be called by the driver that will pass the correct > > > > device which will be already pointing to the config space associated with > > > > the endpoint for instance. Because the driver is already attached to the > > > > endpoint through the vendor ID and device ID specified, there is no need > > > > to do that validation, it will be redundant. > > > > > > Okay. Please amend the kernel-doc to make it explicit that it's the > > > caller's responsibility to check the vendor ID. > > > > I don't think that would be necessary, as I said, the 'struct pci_dev *' > > already points exclusively for the device' config space, which contains > > all the capabilities for that particular device by his turn will be > > attached to a specific driver by the Vendor and Device IDs to a specific > > driver, that will know, firstly search for the specific device vendor ID, > > and then secondly how to decode it, and thirdly to do something with it. > > The helper you're adding may not only be called from drivers but also > from generic PCI code (such as set_pcie_thunderbolt()). In that case > the vendor ID is arbitrary. Also, it doesn't *hurt* documenting this > requirement, does it? I understand now your PoV. In that case, I can add that info to the function comment. > > Thanks, > > Lukas
diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c index b9fecc2..4ea6dd4 100644 --- a/drivers/pci/pci.c +++ b/drivers/pci/pci.c @@ -693,6 +693,35 @@ u8 pci_find_ht_capability(struct pci_dev *dev, int ht_cap) EXPORT_SYMBOL_GPL(pci_find_ht_capability); /** + * pci_find_vsec_capability - Find a vendor-specific extended capability + * @dev: PCI device to query + * @cap: vendor-specific capability ID code + * + * Returns the address of the vendor-specific structure that matches the + * requested capability ID code within the device's PCI configuration space + * or 0 if it does not find a match. + */ +u16 pci_find_vsec_capability(struct pci_dev *dev, int vsec_cap_id) +{ + u16 vsec; + u32 header; + + vsec = pci_find_ext_capability(dev, PCI_EXT_CAP_ID_VNDR); + while (vsec) { + if (pci_read_config_dword(dev, vsec + PCI_VSEC_HDR, + &header) == PCIBIOS_SUCCESSFUL && + PCI_VSEC_CAP_ID(header) == vsec_cap_id) + return vsec; + + vsec = pci_find_next_ext_capability(dev, vsec, + PCI_EXT_CAP_ID_VNDR); + } + + return 0; +} +EXPORT_SYMBOL_GPL(pci_find_vsec_capability); + +/** * pci_find_parent_resource - return resource region of parent bus of given * region * @dev: PCI device structure contains resources to be searched diff --git a/include/linux/pci.h b/include/linux/pci.h index b32126d..da6ab6a 100644 --- a/include/linux/pci.h +++ b/include/linux/pci.h @@ -1080,6 +1080,8 @@ struct pci_bus *pci_find_next_bus(const struct pci_bus *from); u64 pci_get_dsn(struct pci_dev *dev); +u16 pci_find_vsec_capability(struct pci_dev *dev, int vsec_cap_id); + struct pci_dev *pci_get_device(unsigned int vendor, unsigned int device, struct pci_dev *from); struct pci_dev *pci_get_subsys(unsigned int vendor, unsigned int device, diff --git a/include/uapi/linux/pci_regs.h b/include/uapi/linux/pci_regs.h index e709ae8..deae275 100644 --- a/include/uapi/linux/pci_regs.h +++ b/include/uapi/linux/pci_regs.h @@ -983,6 +983,12 @@ #define PCI_VSEC_HDR 4 /* extended cap - vendor-specific */ #define PCI_VSEC_HDR_LEN_SHIFT 20 /* shift for length field */ +/* Vendor-Specific Extended Capabilities */ +#define PCI_VSEC_HEADER 4 /* Vendor-Specific Header */ +#define PCI_VSEC_CAP_ID(x) ((x) & 0xffff) +#define PCI_VSEC_CAP_REV(x) (((x) >> 16) & 0xf) +#define PCI_VSEC_CAP_LEN(x) (((x) >> 20) & 0xfff) + /* SATA capability */ #define PCI_SATA_REGS 4 /* SATA REGs specifier */ #define PCI_SATA_REGS_MASK 0xF /* location - BAR#/inline */
Add pci_find_vsec_capability() that crawls through the device config space searching in all Vendor-Specific Extended Capabilities for a particular capability ID. Vendor-Specific Extended Capability (VSEC) is a PCIe capability (acts like a wrapper) specified by PCI-SIG that allows the vendor to create their own and specific capability in the device config space. Signed-off-by: Gustavo Pimentel <gustavo.pimentel@synopsys.com> --- drivers/pci/pci.c | 29 +++++++++++++++++++++++++++++ include/linux/pci.h | 2 ++ include/uapi/linux/pci_regs.h | 6 ++++++ 3 files changed, 37 insertions(+)