[PATCH v8 2/6] PCI: add resizeable BAR infrastructure v5
Christian König
deathsimple at vodafone.de
Mon Jul 10 14:59:50 UTC 2017
From: Christian König <christian.koenig at 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.koenig at amd.com>
Reviewed-by: Andy Shevchenko <andy.shevchenko at gmail.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 d88edf5..647b799 100644
--- a/drivers/pci/pci.c
+++ b/drivers/pci/pci.c
@@ -2957,6 +2957,110 @@ 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 136a0f9..e494f1e 100644
--- a/drivers/pci/pci.h
+++ b/drivers/pci/pci.h
@@ -367,4 +367,12 @@ int acpi_get_rc_resources(struct device *dev, const char *hid, u16 segment,
struct resource *res);
#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 c22d3eb..d6a075d 100644
--- a/include/uapi/linux/pci_regs.h
+++ b/include/uapi/linux/pci_regs.h
@@ -943,9 +943,16 @@
#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
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