Commit 276b738d authored by Christian König's avatar Christian König Committed by Bjorn Helgaas
Browse files

PCI: Add resizable BAR infrastructure 

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: default avatarChristian 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: default avatarBjorn Helgaas <bhelgaas@google.com>
Reviewed-by: default avatarAndy Shevchenko <andy.shevchenko@gmail.com>
parent cb21bc94

drivers/pci/pci.c

+101 −0
Original line number Diff line number Diff line
@@ -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

drivers/pci/pci.h

+8 −0
Original line number Diff line number Diff line
@@ -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 */

include/uapi/linux/pci_regs.h

+6 −2
Original line number Diff line number Diff line
@@ -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 */

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