From: Christian König <christian.koe...@amd.com> Just the defines and helper functions to read the possible sizes of a BAR and update it's size.
See https://pcisig.com/sites/default/files/specification_documents/ECN_Resizable-BAR_24Apr2008.pdf and PCIe r3.1, sec 7.22. This is useful for hardware with large local storage (mostly GFX) which only expose 256MB BARs initially to be compatible with 32bit systems. v2: provide read helper as well v3: improve function names, use unsigned values, add better comments. v4: move definition, improve commit message, s/bar/BAR/ v5: split out helper to find ctrl reg pos, style fixes, comment fixes, add pci_rbar_size_to_bytes as well Signed-off-by: Christian König <christian.koe...@amd.com> --- drivers/pci/pci.c | 104 ++++++++++++++++++++++++++++++++++++++++++ drivers/pci/pci.h | 8 ++++ include/uapi/linux/pci_regs.h | 11 ++++- 3 files changed, 121 insertions(+), 2 deletions(-) diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c index ba34907..0cbf4a6 100644 --- a/drivers/pci/pci.c +++ b/drivers/pci/pci.c @@ -2944,6 +2944,110 @@ bool pci_acs_path_enabled(struct pci_dev *start, } /** + * pci_rbar_find_pos - find position of resize ctrl reg for BAR + * @dev: PCI device + * @bar: BAR to find + * + * Helper to find the postion of the ctrl register for a BAR. + * Returns -ENOTSUPP of resizeable BARs are not supported at all. + * Returns -ENOENT if not ctrl register for the BAR could be found. + */ +static int pci_rbar_find_pos(struct pci_dev *pdev, int bar) +{ + unsigned int pos, nbars; + unsigned int i; + u32 ctrl; + + pos = pci_find_ext_capability(pdev, PCI_EXT_CAP_ID_REBAR); + if (!pos) + return -ENOTSUPP; + + pci_read_config_dword(pdev, pos + PCI_REBAR_CTRL, &ctrl); + nbars = (ctrl & PCI_REBAR_CTRL_NBAR_MASK) >> PCI_REBAR_CTRL_NBAR_SHIFT; + + for (i = 0; i < nbars; ++i, pos += 8) { + int bar_idx; + + pci_read_config_dword(pdev, pos + PCI_REBAR_CTRL, &ctrl); + bar_idx = (ctrl & PCI_REBAR_CTRL_BAR_IDX_MASK) >> + PCI_REBAR_CTRL_BAR_IDX_SHIFT; + if (bar_idx == bar) + return pos; + } + + return -ENOENT; +} + +/** + * pci_rbar_get_possible_sizes - get possible sizes for BAR + * @dev: PCI device + * @bar: BAR to query + * + * Get the possible sizes of a resizeable BAR as bitmask defined in the spec + * (bit 0=1MB, bit 19=512GB). Returns 0 if BAR isn't resizeable. + */ +u32 pci_rbar_get_possible_sizes(struct pci_dev *pdev, int bar) +{ + u32 cap; + int pos; + + pos = pci_rbar_find_pos(pdev, bar); + if (pos < 0) + return 0; + + pci_read_config_dword(pdev, pos + PCI_REBAR_CAP, &cap); + return (cap & PCI_REBAR_CTRL_SIZES_MASK) >> + PCI_REBAR_CTRL_SIZES_SHIFT; +} + +/** + * pci_rbar_get_current_size - get the current size of a BAR + * @dev: PCI device + * @bar: BAR to set size to + * + * Read the size of a BAR from the resizeable BAR config. + * Returns size if found or negative error code. + */ +int pci_rbar_get_current_size(struct pci_dev *pdev, int bar) +{ + u32 ctrl; + int pos; + + pos = pci_rbar_find_pos(pdev, bar); + if (pos < 0) + return pos; + + pci_read_config_dword(pdev, pos + PCI_REBAR_CTRL, &ctrl); + return (ctrl & PCI_REBAR_CTRL_BAR_SIZE_MASK) >> + PCI_REBAR_CTRL_BAR_SIZE_SHIFT; +} + +/** + * pci_rbar_set_size - set a new size for a BAR + * @dev: PCI device + * @bar: BAR to set size to + * @size: new size as defined in the spec (0=1MB, 19=512GB) + * + * Set the new size of a BAR as defined in the spec. + * Returns zero if resizing was successful, error code otherwise. + */ +int pci_rbar_set_size(struct pci_dev *pdev, int bar, int size) +{ + u32 ctrl; + int pos; + + pos = pci_rbar_find_pos(pdev, bar); + if (pos < 0) + return pos; + + pci_read_config_dword(pdev, pos + PCI_REBAR_CTRL, &ctrl); + ctrl &= ~PCI_REBAR_CTRL_BAR_SIZE_MASK; + ctrl |= size << PCI_REBAR_CTRL_BAR_SIZE_SHIFT; + pci_write_config_dword(pdev, pos + PCI_REBAR_CTRL, ctrl); + return 0; +} + +/** * pci_swizzle_interrupt_pin - swizzle INTx for device behind bridge * @dev: the PCI device * @pin: the INTx pin (1=INTA, 2=INTB, 3=INTC, 4=INTD) diff --git a/drivers/pci/pci.h b/drivers/pci/pci.h index 3868828..6290e5c 100644 --- a/drivers/pci/pci.h +++ b/drivers/pci/pci.h @@ -359,4 +359,12 @@ static inline int pci_dev_specific_reset(struct pci_dev *dev, int probe) } #endif +u32 pci_rbar_get_possible_sizes(struct pci_dev *pdev, int bar); +int pci_rbar_get_current_size(struct pci_dev *pdev, int bar); +int pci_rbar_set_size(struct pci_dev *pdev, int bar, int size); +static inline u64 pci_rbar_size_to_bytes(int size) +{ + return 1ULL << (size + 20); +} + #endif /* DRIVERS_PCI_H */ diff --git a/include/uapi/linux/pci_regs.h b/include/uapi/linux/pci_regs.h index e5a2e68..a75429e 100644 --- a/include/uapi/linux/pci_regs.h +++ b/include/uapi/linux/pci_regs.h @@ -932,9 +932,16 @@ #define PCI_SATA_SIZEOF_LONG 16 /* Resizable BARs */ +#define PCI_REBAR_CAP 4 /* capability register */ +#define PCI_REBAR_CTRL_SIZES_MASK (0xFFFFF << 4) /* mask for sizes */ +#define PCI_REBAR_CTRL_SIZES_SHIFT 4 /* shift for sizes */ #define PCI_REBAR_CTRL 8 /* control register */ -#define PCI_REBAR_CTRL_NBAR_MASK (7 << 5) /* mask for # bars */ -#define PCI_REBAR_CTRL_NBAR_SHIFT 5 /* shift for # bars */ +#define PCI_REBAR_CTRL_BAR_IDX_MASK (7 << 0) /* mask for BAR index */ +#define PCI_REBAR_CTRL_BAR_IDX_SHIFT 0 /* shift for BAR index */ +#define PCI_REBAR_CTRL_NBAR_MASK (7 << 5) /* mask for # BARs */ +#define PCI_REBAR_CTRL_NBAR_SHIFT 5 /* shift for # BARs */ +#define PCI_REBAR_CTRL_BAR_SIZE_MASK (0x1F << 8) /* mask for BAR size */ +#define PCI_REBAR_CTRL_BAR_SIZE_SHIFT 8 /* shift for BAR size */ /* Dynamic Power Allocation */ #define PCI_DPA_CAP 4 /* capability register */ -- 2.7.4
