From 276b738deb5bf856b9f6049fcd92a967f52643d7 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Christian=20K=C3=B6nig?= <christian.koenig@amd.com>
Date: Tue, 24 Oct 2017 14:40:20 -0500
Subject: [PATCH] PCI: Add resizable BAR infrastructure
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Git-commit: 276b738deb5bf856b9f6049fcd92a967f52643d7
Patch-mainline: v4.15-rc1
References: bsc#1105355
Add resizable BAR infrastructure, including defines and helper functions to
read the possible sizes of a BAR and update its size. See PCIe r3.1, sec
7.22.
Link: https://pcisig.com/sites/default/files/specification_documents/ECN_Resizable-BAR_24Apr2008.pdf
Signed-off-by: Christian König <christian.koenig@amd.com>
[bhelgaas: rename to functions with "rebar" (to match #defines), drop shift
#defines, drop "_MASK" suffixes, fix typos, fix kerneldoc]
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Reviewed-by: Andy Shevchenko <andy.shevchenko@gmail.com>
Acked-by: Takashi Iwai <tiwai@suse.de>
---
drivers/pci/pci.c | 101 ++++++++++++++++++++++++++++++++++
drivers/pci/pci.h | 8 +++
include/uapi/linux/pci_regs.h | 8 ++-
3 files changed, 115 insertions(+), 2 deletions(-)
diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c
index 6078dfc11b11..832b96756e83 100644
--- a/drivers/pci/pci.c
+++ b/drivers/pci/pci.c
@@ -2965,6 +2965,107 @@ bool pci_acs_path_enabled(struct pci_dev *start,
return true;
}
+/**
+ * pci_rebar_find_pos - find position of resize ctrl reg for BAR
+ * @pdev: PCI device
+ * @bar: BAR to find
+ *
+ * Helper to find the position of the ctrl register for a BAR.
+ * Returns -ENOTSUPP if resizable BARs are not supported at all.
+ * Returns -ENOENT if no ctrl register for the BAR could be found.
+ */
+static int pci_rebar_find_pos(struct pci_dev *pdev, int bar)
+{
+ unsigned int pos, nbars, 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;
+ if (bar_idx == bar)
+ return pos;
+ }
+
+ return -ENOENT;
+}
+
+/**
+ * pci_rebar_get_possible_sizes - get possible sizes for BAR
+ * @pdev: PCI device
+ * @bar: BAR to query
+ *
+ * Get the possible sizes of a resizable BAR as bitmask defined in the spec
+ * (bit 0=1MB, bit 19=512GB). Returns 0 if BAR isn't resizable.
+ */
+u32 pci_rebar_get_possible_sizes(struct pci_dev *pdev, int bar)
+{
+ int pos;
+ u32 cap;
+
+ pos = pci_rebar_find_pos(pdev, bar);
+ if (pos < 0)
+ return 0;
+
+ pci_read_config_dword(pdev, pos + PCI_REBAR_CAP, &cap);
+ return (cap & PCI_REBAR_CAP_SIZES) >> 4;
+}
+
+/**
+ * pci_rebar_get_current_size - get the current size of a BAR
+ * @pdev: PCI device
+ * @bar: BAR to set size to
+ *
+ * Read the size of a BAR from the resizable BAR config.
+ * Returns size if found or negative error code.
+ */
+int pci_rebar_get_current_size(struct pci_dev *pdev, int bar)
+{
+ int pos;
+ u32 ctrl;
+
+ pos = pci_rebar_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) >> 8;
+}
+
+/**
+ * pci_rebar_set_size - set a new size for a BAR
+ * @pdev: 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_rebar_set_size(struct pci_dev *pdev, int bar, int size)
+{
+ int pos;
+ u32 ctrl;
+
+ pos = pci_rebar_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;
+ ctrl |= size << 8;
+ 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
diff --git a/drivers/pci/pci.h b/drivers/pci/pci.h
index a6560c9baa52..33469a33738d 100644
--- a/drivers/pci/pci.h
+++ b/drivers/pci/pci.h
@@ -366,4 +366,12 @@ int acpi_get_rc_resources(struct device *dev, const char *hid, u16 segment,
struct resource *res);
#endif
+u32 pci_rebar_get_possible_sizes(struct pci_dev *pdev, int bar);
+int pci_rebar_get_current_size(struct pci_dev *pdev, int bar);
+int pci_rebar_set_size(struct pci_dev *pdev, int bar, int size);
+static inline u64 pci_rebar_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 f8d58045926f..d34000a59f24 100644
--- a/include/uapi/linux/pci_regs.h
+++ b/include/uapi/linux/pci_regs.h
@@ -939,9 +939,13 @@
#define PCI_SATA_SIZEOF_LONG 16
/* Resizable BARs */
+#define PCI_REBAR_CAP 4 /* capability register */
+#define PCI_REBAR_CAP_SIZES 0x00FFFFF0 /* supported BAR 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 0x00000007 /* BAR index */
+#define PCI_REBAR_CTRL_NBAR_MASK 0x000000E0 /* # of resizable BARs */
+#define PCI_REBAR_CTRL_NBAR_SHIFT 5 /* shift for # of BARs */
+#define PCI_REBAR_CTRL_BAR_SIZE 0x00001F00 /* BAR size */
/* Dynamic Power Allocation */
#define PCI_DPA_CAP 4 /* capability register */
--
2.18.0