1 files changed, 247 insertions, 0 deletions
diff --git a/drivers/pci/rebar.c b/drivers/pci/rebar.c
new file mode 100644
index 000000000000..f6ed7e4893a7
--- /dev/null
+++ b/drivers/pci/rebar.c
@@ -0,0 +1,247 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * PCI Resizable BAR Extended Capability handling.
+ */
+
+#include <linux/bitfield.h>
+#include <linux/errno.h>
+#include <linux/export.h>
+#include <linux/ioport.h>
+#include <linux/pci.h>
+#include <linux/types.h>
+
+#include "pci.h"
+
+void pci_rebar_init(struct pci_dev *pdev)
+{
+	pdev->rebar_cap = pci_find_ext_capability(pdev, PCI_EXT_CAP_ID_REBAR);
+}
+
+/**
+ * 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;
+
+	if (pci_resource_is_iov(bar)) {
+		pos = pci_iov_vf_rebar_cap(pdev);
+		bar = pci_resource_num_to_vf_bar(bar);
+	} else {
+		pos = pdev->rebar_cap;
+	}
+
+	if (!pos)
+		return -ENOTSUPP;
+
+	pci_read_config_dword(pdev, pos + PCI_REBAR_CTRL, &ctrl);
+	nbars = FIELD_GET(PCI_REBAR_CTRL_NBAR_MASK, ctrl);
+
+	for (i = 0; i < nbars; i++, pos += 8) {
+		int bar_idx;
+
+		pci_read_config_dword(pdev, pos + PCI_REBAR_CTRL, &ctrl);
+		bar_idx = FIELD_GET(PCI_REBAR_CTRL_BAR_IDX, ctrl);
+		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 31=128TB). 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);
+	cap = FIELD_GET(PCI_REBAR_CAP_SIZES, cap);
+
+	/* Sapphire RX 5600 XT Pulse has an invalid cap dword for BAR 0 */
+	if (pdev->vendor == PCI_VENDOR_ID_ATI && pdev->device == 0x731f &&
+	    bar == 0 && cap == 0x700)
+		return 0x3f00;
+
+	return cap;
+}
+EXPORT_SYMBOL(pci_rebar_get_possible_sizes);
+
+/**
+ * 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 FIELD_GET(PCI_REBAR_CTRL_BAR_SIZE, ctrl);
+}
+
+/**
+ * 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, 31=128TB)
+ *
+ * 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 |= FIELD_PREP(PCI_REBAR_CTRL_BAR_SIZE, size);
+	pci_write_config_dword(pdev, pos + PCI_REBAR_CTRL, ctrl);
+
+	if (pci_resource_is_iov(bar))
+		pci_iov_resource_set_size(pdev, bar, size);
+
+	return 0;
+}
+
+void pci_restore_rebar_state(struct pci_dev *pdev)
+{
+	unsigned int pos, nbars, i;
+	u32 ctrl;
+
+	pos = pdev->rebar_cap;
+	if (!pos)
+		return;
+
+	pci_read_config_dword(pdev, pos + PCI_REBAR_CTRL, &ctrl);
+	nbars = FIELD_GET(PCI_REBAR_CTRL_NBAR_MASK, ctrl);
+
+	for (i = 0; i < nbars; i++, pos += 8) {
+		struct resource *res;
+		int bar_idx, size;
+
+		pci_read_config_dword(pdev, pos + PCI_REBAR_CTRL, &ctrl);
+		bar_idx = ctrl & PCI_REBAR_CTRL_BAR_IDX;
+		res = pci_resource_n(pdev, bar_idx);
+		size = pci_rebar_bytes_to_size(resource_size(res));
+		ctrl &= ~PCI_REBAR_CTRL_BAR_SIZE;
+		ctrl |= FIELD_PREP(PCI_REBAR_CTRL_BAR_SIZE, size);
+		pci_write_config_dword(pdev, pos + PCI_REBAR_CTRL, ctrl);
+	}
+}
+
+static bool pci_resize_is_memory_decoding_enabled(struct pci_dev *dev,
+						  int resno)
+{
+	u16 cmd;
+
+	if (pci_resource_is_iov(resno))
+		return pci_iov_is_memory_decoding_enabled(dev);
+
+	pci_read_config_word(dev, PCI_COMMAND, &cmd);
+
+	return cmd & PCI_COMMAND_MEMORY;
+}
+
+void pci_resize_resource_set_size(struct pci_dev *dev, int resno, int size)
+{
+	resource_size_t res_size = pci_rebar_size_to_bytes(size);
+	struct resource *res = pci_resource_n(dev, resno);
+
+	if (pci_resource_is_iov(resno))
+		res_size *= pci_sriov_get_totalvfs(dev);
+
+	resource_set_size(res, res_size);
+}
+
+/**
+ * pci_resize_resource - reconfigure a Resizable BAR and resources
+ * @dev: the PCI device
+ * @resno: index of the BAR to be resized
+ * @size: new size as defined in the spec (0=1MB, 31=128TB)
+ * @exclude_bars: a mask of BARs that should not be released
+ *
+ * Reconfigure @resno to @size and re-run resource assignment algorithm
+ * with the new size.
+ *
+ * Prior to resize, release @dev resources that share a bridge window with
+ * @resno.  This unpins the bridge window resource to allow changing it.
+ *
+ * The caller may prevent releasing a particular BAR by providing
+ * @exclude_bars mask, but this may result in the resize operation failing
+ * due to insufficient space.
+ *
+ * Return: 0 on success, or negative on error. In case of an error, the
+ *         resources are restored to their original places.
+ */
+int pci_resize_resource(struct pci_dev *dev, int resno, int size,
+			int exclude_bars)
+{
+	struct pci_host_bridge *host;
+	int old, ret;
+	u32 sizes;
+
+	/* Check if we must preserve the firmware's resource assignment */
+	host = pci_find_host_bridge(dev->bus);
+	if (host->preserve_config)
+		return -ENOTSUPP;
+
+	if (pci_resize_is_memory_decoding_enabled(dev, resno))
+		return -EBUSY;
+
+	sizes = pci_rebar_get_possible_sizes(dev, resno);
+	if (!sizes)
+		return -ENOTSUPP;
+
+	if (!(sizes & BIT(size)))
+		return -EINVAL;
+
+	old = pci_rebar_get_current_size(dev, resno);
+	if (old < 0)
+		return old;
+
+	ret = pci_rebar_set_size(dev, resno, size);
+	if (ret)
+		return ret;
+
+	ret = pci_do_resource_release_and_resize(dev, resno, size, exclude_bars);
+	if (ret)
+		goto error_resize;
+	return 0;
+
+error_resize:
+	pci_rebar_set_size(dev, resno, old);
+	return ret;
+}
+EXPORT_SYMBOL(pci_resize_resource);