Revision e2093926a098a8ccf0f1d10f6df8dad452cb28d3 authored by Ross Zwisler on 02 June 2017, 21:46:37 UTC, committed by Linus Torvalds on 02 June 2017, 22:07:37 UTC
We currently have two related PMD vs PTE races in the DAX code.  These
can both be easily triggered by having two threads reading and writing
simultaneously to the same private mapping, with the key being that
private mapping reads can be handled with PMDs but private mapping
writes are always handled with PTEs so that we can COW.

Here is the first race:

  CPU 0					CPU 1

  (private mapping write)
  __handle_mm_fault()
    create_huge_pmd() - FALLBACK
    handle_pte_fault()
      passes check for pmd_devmap()

					(private mapping read)
					__handle_mm_fault()
					  create_huge_pmd()
					    dax_iomap_pmd_fault() inserts PMD

      dax_iomap_pte_fault() does a PTE fault, but we already have a DAX PMD
      			  installed in our page tables at this spot.

Here's the second race:

  CPU 0					CPU 1

  (private mapping read)
  __handle_mm_fault()
    passes check for pmd_none()
    create_huge_pmd()
      dax_iomap_pmd_fault() inserts PMD

  (private mapping write)
  __handle_mm_fault()
    create_huge_pmd() - FALLBACK
					(private mapping read)
					__handle_mm_fault()
					  passes check for pmd_none()
					  create_huge_pmd()

    handle_pte_fault()
      dax_iomap_pte_fault() inserts PTE
					    dax_iomap_pmd_fault() inserts PMD,
					       but we already have a PTE at
					       this spot.

The core of the issue is that while there is isolation between faults to
the same range in the DAX fault handlers via our DAX entry locking,
there is no isolation between faults in the code in mm/memory.c.  This
means for instance that this code in __handle_mm_fault() can run:

	if (pmd_none(*vmf.pmd) && transparent_hugepage_enabled(vma)) {
		ret = create_huge_pmd(&vmf);

But by the time we actually get to run the fault handler called by
create_huge_pmd(), the PMD is no longer pmd_none() because a racing PTE
fault has installed a normal PMD here as a parent.  This is the cause of
the 2nd race.  The first race is similar - there is the following check
in handle_pte_fault():

	} else {
		/* See comment in pte_alloc_one_map() */
		if (pmd_devmap(*vmf->pmd) || pmd_trans_unstable(vmf->pmd))
			return 0;

So if a pmd_devmap() PMD (a DAX PMD) has been installed at vmf->pmd, we
will bail and retry the fault.  This is correct, but there is nothing
preventing the PMD from being installed after this check but before we
actually get to the DAX PTE fault handlers.

In my testing these races result in the following types of errors:

  BUG: Bad rss-counter state mm:ffff8800a817d280 idx:1 val:1
  BUG: non-zero nr_ptes on freeing mm: 15

Fix this issue by having the DAX fault handlers verify that it is safe
to continue their fault after they have taken an entry lock to block
other racing faults.

[ross.zwisler@linux.intel.com: improve fix for colliding PMD & PTE entries]
  Link: http://lkml.kernel.org/r/20170526195932.32178-1-ross.zwisler@linux.intel.com
Link: http://lkml.kernel.org/r/20170522215749.23516-2-ross.zwisler@linux.intel.com
Signed-off-by: Ross Zwisler <ross.zwisler@linux.intel.com>
Reported-by: Pawel Lebioda <pawel.lebioda@intel.com>
Reviewed-by: Jan Kara <jack@suse.cz>
Cc: "Darrick J. Wong" <darrick.wong@oracle.com>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: Dave Hansen <dave.hansen@intel.com>
Cc: Matthew Wilcox <mawilcox@microsoft.com>
Cc: "Kirill A . Shutemov" <kirill.shutemov@linux.intel.com>
Cc: Pawel Lebioda <pawel.lebioda@intel.com>
Cc: Dave Jiang <dave.jiang@intel.com>
Cc: Xiong Zhou <xzhou@redhat.com>
Cc: Eryu Guan <eguan@redhat.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
1 parent d0f0931
Raw File
sdio_io.c
/*
 *  linux/drivers/mmc/core/sdio_io.c
 *
 *  Copyright 2007-2008 Pierre Ossman
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or (at
 * your option) any later version.
 */

#include <linux/export.h>
#include <linux/mmc/host.h>
#include <linux/mmc/card.h>
#include <linux/mmc/sdio.h>
#include <linux/mmc/sdio_func.h>

#include "sdio_ops.h"
#include "core.h"
#include "card.h"

/**
 *	sdio_claim_host - exclusively claim a bus for a certain SDIO function
 *	@func: SDIO function that will be accessed
 *
 *	Claim a bus for a set of operations. The SDIO function given
 *	is used to figure out which bus is relevant.
 */
void sdio_claim_host(struct sdio_func *func)
{
	if (WARN_ON(!func))
		return;

	mmc_claim_host(func->card->host);
}
EXPORT_SYMBOL_GPL(sdio_claim_host);

/**
 *	sdio_release_host - release a bus for a certain SDIO function
 *	@func: SDIO function that was accessed
 *
 *	Release a bus, allowing others to claim the bus for their
 *	operations.
 */
void sdio_release_host(struct sdio_func *func)
{
	if (WARN_ON(!func))
		return;

	mmc_release_host(func->card->host);
}
EXPORT_SYMBOL_GPL(sdio_release_host);

/**
 *	sdio_enable_func - enables a SDIO function for usage
 *	@func: SDIO function to enable
 *
 *	Powers up and activates a SDIO function so that register
 *	access is possible.
 */
int sdio_enable_func(struct sdio_func *func)
{
	int ret;
	unsigned char reg;
	unsigned long timeout;

	if (!func)
		return -EINVAL;

	pr_debug("SDIO: Enabling device %s...\n", sdio_func_id(func));

	ret = mmc_io_rw_direct(func->card, 0, 0, SDIO_CCCR_IOEx, 0, &reg);
	if (ret)
		goto err;

	reg |= 1 << func->num;

	ret = mmc_io_rw_direct(func->card, 1, 0, SDIO_CCCR_IOEx, reg, NULL);
	if (ret)
		goto err;

	timeout = jiffies + msecs_to_jiffies(func->enable_timeout);

	while (1) {
		ret = mmc_io_rw_direct(func->card, 0, 0, SDIO_CCCR_IORx, 0, &reg);
		if (ret)
			goto err;
		if (reg & (1 << func->num))
			break;
		ret = -ETIME;
		if (time_after(jiffies, timeout))
			goto err;
	}

	pr_debug("SDIO: Enabled device %s\n", sdio_func_id(func));

	return 0;

err:
	pr_debug("SDIO: Failed to enable device %s\n", sdio_func_id(func));
	return ret;
}
EXPORT_SYMBOL_GPL(sdio_enable_func);

/**
 *	sdio_disable_func - disable a SDIO function
 *	@func: SDIO function to disable
 *
 *	Powers down and deactivates a SDIO function. Register access
 *	to this function will fail until the function is reenabled.
 */
int sdio_disable_func(struct sdio_func *func)
{
	int ret;
	unsigned char reg;

	if (!func)
		return -EINVAL;

	pr_debug("SDIO: Disabling device %s...\n", sdio_func_id(func));

	ret = mmc_io_rw_direct(func->card, 0, 0, SDIO_CCCR_IOEx, 0, &reg);
	if (ret)
		goto err;

	reg &= ~(1 << func->num);

	ret = mmc_io_rw_direct(func->card, 1, 0, SDIO_CCCR_IOEx, reg, NULL);
	if (ret)
		goto err;

	pr_debug("SDIO: Disabled device %s\n", sdio_func_id(func));

	return 0;

err:
	pr_debug("SDIO: Failed to disable device %s\n", sdio_func_id(func));
	return -EIO;
}
EXPORT_SYMBOL_GPL(sdio_disable_func);

/**
 *	sdio_set_block_size - set the block size of an SDIO function
 *	@func: SDIO function to change
 *	@blksz: new block size or 0 to use the default.
 *
 *	The default block size is the largest supported by both the function
 *	and the host, with a maximum of 512 to ensure that arbitrarily sized
 *	data transfer use the optimal (least) number of commands.
 *
 *	A driver may call this to override the default block size set by the
 *	core. This can be used to set a block size greater than the maximum
 *	that reported by the card; it is the driver's responsibility to ensure
 *	it uses a value that the card supports.
 *
 *	Returns 0 on success, -EINVAL if the host does not support the
 *	requested block size, or -EIO (etc.) if one of the resultant FBR block
 *	size register writes failed.
 *
 */
int sdio_set_block_size(struct sdio_func *func, unsigned blksz)
{
	int ret;

	if (blksz > func->card->host->max_blk_size)
		return -EINVAL;

	if (blksz == 0) {
		blksz = min(func->max_blksize, func->card->host->max_blk_size);
		blksz = min(blksz, 512u);
	}

	ret = mmc_io_rw_direct(func->card, 1, 0,
		SDIO_FBR_BASE(func->num) + SDIO_FBR_BLKSIZE,
		blksz & 0xff, NULL);
	if (ret)
		return ret;
	ret = mmc_io_rw_direct(func->card, 1, 0,
		SDIO_FBR_BASE(func->num) + SDIO_FBR_BLKSIZE + 1,
		(blksz >> 8) & 0xff, NULL);
	if (ret)
		return ret;
	func->cur_blksize = blksz;
	return 0;
}
EXPORT_SYMBOL_GPL(sdio_set_block_size);

/*
 * Calculate the maximum byte mode transfer size
 */
static inline unsigned int sdio_max_byte_size(struct sdio_func *func)
{
	unsigned mval =	func->card->host->max_blk_size;

	if (mmc_blksz_for_byte_mode(func->card))
		mval = min(mval, func->cur_blksize);
	else
		mval = min(mval, func->max_blksize);

	if (mmc_card_broken_byte_mode_512(func->card))
		return min(mval, 511u);

	return min(mval, 512u); /* maximum size for byte mode */
}

/**
 *	sdio_align_size - pads a transfer size to a more optimal value
 *	@func: SDIO function
 *	@sz: original transfer size
 *
 *	Pads the original data size with a number of extra bytes in
 *	order to avoid controller bugs and/or performance hits
 *	(e.g. some controllers revert to PIO for certain sizes).
 *
 *	If possible, it will also adjust the size so that it can be
 *	handled in just a single request.
 *
 *	Returns the improved size, which might be unmodified.
 */
unsigned int sdio_align_size(struct sdio_func *func, unsigned int sz)
{
	unsigned int orig_sz;
	unsigned int blk_sz, byte_sz;
	unsigned chunk_sz;

	orig_sz = sz;

	/*
	 * Do a first check with the controller, in case it
	 * wants to increase the size up to a point where it
	 * might need more than one block.
	 */
	sz = mmc_align_data_size(func->card, sz);

	/*
	 * If we can still do this with just a byte transfer, then
	 * we're done.
	 */
	if (sz <= sdio_max_byte_size(func))
		return sz;

	if (func->card->cccr.multi_block) {
		/*
		 * Check if the transfer is already block aligned
		 */
		if ((sz % func->cur_blksize) == 0)
			return sz;

		/*
		 * Realign it so that it can be done with one request,
		 * and recheck if the controller still likes it.
		 */
		blk_sz = ((sz + func->cur_blksize - 1) /
			func->cur_blksize) * func->cur_blksize;
		blk_sz = mmc_align_data_size(func->card, blk_sz);

		/*
		 * This value is only good if it is still just
		 * one request.
		 */
		if ((blk_sz % func->cur_blksize) == 0)
			return blk_sz;

		/*
		 * We failed to do one request, but at least try to
		 * pad the remainder properly.
		 */
		byte_sz = mmc_align_data_size(func->card,
				sz % func->cur_blksize);
		if (byte_sz <= sdio_max_byte_size(func)) {
			blk_sz = sz / func->cur_blksize;
			return blk_sz * func->cur_blksize + byte_sz;
		}
	} else {
		/*
		 * We need multiple requests, so first check that the
		 * controller can handle the chunk size;
		 */
		chunk_sz = mmc_align_data_size(func->card,
				sdio_max_byte_size(func));
		if (chunk_sz == sdio_max_byte_size(func)) {
			/*
			 * Fix up the size of the remainder (if any)
			 */
			byte_sz = orig_sz % chunk_sz;
			if (byte_sz) {
				byte_sz = mmc_align_data_size(func->card,
						byte_sz);
			}

			return (orig_sz / chunk_sz) * chunk_sz + byte_sz;
		}
	}

	/*
	 * The controller is simply incapable of transferring the size
	 * we want in decent manner, so just return the original size.
	 */
	return orig_sz;
}
EXPORT_SYMBOL_GPL(sdio_align_size);

/* Split an arbitrarily sized data transfer into several
 * IO_RW_EXTENDED commands. */
static int sdio_io_rw_ext_helper(struct sdio_func *func, int write,
	unsigned addr, int incr_addr, u8 *buf, unsigned size)
{
	unsigned remainder = size;
	unsigned max_blocks;
	int ret;

	if (!func || (func->num > 7))
		return -EINVAL;

	/* Do the bulk of the transfer using block mode (if supported). */
	if (func->card->cccr.multi_block && (size > sdio_max_byte_size(func))) {
		/* Blocks per command is limited by host count, host transfer
		 * size and the maximum for IO_RW_EXTENDED of 511 blocks. */
		max_blocks = min(func->card->host->max_blk_count, 511u);

		while (remainder >= func->cur_blksize) {
			unsigned blocks;

			blocks = remainder / func->cur_blksize;
			if (blocks > max_blocks)
				blocks = max_blocks;
			size = blocks * func->cur_blksize;

			ret = mmc_io_rw_extended(func->card, write,
				func->num, addr, incr_addr, buf,
				blocks, func->cur_blksize);
			if (ret)
				return ret;

			remainder -= size;
			buf += size;
			if (incr_addr)
				addr += size;
		}
	}

	/* Write the remainder using byte mode. */
	while (remainder > 0) {
		size = min(remainder, sdio_max_byte_size(func));

		/* Indicate byte mode by setting "blocks" = 0 */
		ret = mmc_io_rw_extended(func->card, write, func->num, addr,
			 incr_addr, buf, 0, size);
		if (ret)
			return ret;

		remainder -= size;
		buf += size;
		if (incr_addr)
			addr += size;
	}
	return 0;
}

/**
 *	sdio_readb - read a single byte from a SDIO function
 *	@func: SDIO function to access
 *	@addr: address to read
 *	@err_ret: optional status value from transfer
 *
 *	Reads a single byte from the address space of a given SDIO
 *	function. If there is a problem reading the address, 0xff
 *	is returned and @err_ret will contain the error code.
 */
u8 sdio_readb(struct sdio_func *func, unsigned int addr, int *err_ret)
{
	int ret;
	u8 val;

	if (!func) {
		if (err_ret)
			*err_ret = -EINVAL;
		return 0xFF;
	}

	ret = mmc_io_rw_direct(func->card, 0, func->num, addr, 0, &val);
	if (err_ret)
		*err_ret = ret;
	if (ret)
		return 0xFF;

	return val;
}
EXPORT_SYMBOL_GPL(sdio_readb);

/**
 *	sdio_writeb - write a single byte to a SDIO function
 *	@func: SDIO function to access
 *	@b: byte to write
 *	@addr: address to write to
 *	@err_ret: optional status value from transfer
 *
 *	Writes a single byte to the address space of a given SDIO
 *	function. @err_ret will contain the status of the actual
 *	transfer.
 */
void sdio_writeb(struct sdio_func *func, u8 b, unsigned int addr, int *err_ret)
{
	int ret;

	if (!func) {
		if (err_ret)
			*err_ret = -EINVAL;
		return;
	}

	ret = mmc_io_rw_direct(func->card, 1, func->num, addr, b, NULL);
	if (err_ret)
		*err_ret = ret;
}
EXPORT_SYMBOL_GPL(sdio_writeb);

/**
 *	sdio_writeb_readb - write and read a byte from SDIO function
 *	@func: SDIO function to access
 *	@write_byte: byte to write
 *	@addr: address to write to
 *	@err_ret: optional status value from transfer
 *
 *	Performs a RAW (Read after Write) operation as defined by SDIO spec -
 *	single byte is written to address space of a given SDIO function and
 *	response is read back from the same address, both using single request.
 *	If there is a problem with the operation, 0xff is returned and
 *	@err_ret will contain the error code.
 */
u8 sdio_writeb_readb(struct sdio_func *func, u8 write_byte,
	unsigned int addr, int *err_ret)
{
	int ret;
	u8 val;

	ret = mmc_io_rw_direct(func->card, 1, func->num, addr,
			write_byte, &val);
	if (err_ret)
		*err_ret = ret;
	if (ret)
		return 0xff;

	return val;
}
EXPORT_SYMBOL_GPL(sdio_writeb_readb);

/**
 *	sdio_memcpy_fromio - read a chunk of memory from a SDIO function
 *	@func: SDIO function to access
 *	@dst: buffer to store the data
 *	@addr: address to begin reading from
 *	@count: number of bytes to read
 *
 *	Reads from the address space of a given SDIO function. Return
 *	value indicates if the transfer succeeded or not.
 */
int sdio_memcpy_fromio(struct sdio_func *func, void *dst,
	unsigned int addr, int count)
{
	return sdio_io_rw_ext_helper(func, 0, addr, 1, dst, count);
}
EXPORT_SYMBOL_GPL(sdio_memcpy_fromio);

/**
 *	sdio_memcpy_toio - write a chunk of memory to a SDIO function
 *	@func: SDIO function to access
 *	@addr: address to start writing to
 *	@src: buffer that contains the data to write
 *	@count: number of bytes to write
 *
 *	Writes to the address space of a given SDIO function. Return
 *	value indicates if the transfer succeeded or not.
 */
int sdio_memcpy_toio(struct sdio_func *func, unsigned int addr,
	void *src, int count)
{
	return sdio_io_rw_ext_helper(func, 1, addr, 1, src, count);
}
EXPORT_SYMBOL_GPL(sdio_memcpy_toio);

/**
 *	sdio_readsb - read from a FIFO on a SDIO function
 *	@func: SDIO function to access
 *	@dst: buffer to store the data
 *	@addr: address of (single byte) FIFO
 *	@count: number of bytes to read
 *
 *	Reads from the specified FIFO of a given SDIO function. Return
 *	value indicates if the transfer succeeded or not.
 */
int sdio_readsb(struct sdio_func *func, void *dst, unsigned int addr,
	int count)
{
	return sdio_io_rw_ext_helper(func, 0, addr, 0, dst, count);
}
EXPORT_SYMBOL_GPL(sdio_readsb);

/**
 *	sdio_writesb - write to a FIFO of a SDIO function
 *	@func: SDIO function to access
 *	@addr: address of (single byte) FIFO
 *	@src: buffer that contains the data to write
 *	@count: number of bytes to write
 *
 *	Writes to the specified FIFO of a given SDIO function. Return
 *	value indicates if the transfer succeeded or not.
 */
int sdio_writesb(struct sdio_func *func, unsigned int addr, void *src,
	int count)
{
	return sdio_io_rw_ext_helper(func, 1, addr, 0, src, count);
}
EXPORT_SYMBOL_GPL(sdio_writesb);

/**
 *	sdio_readw - read a 16 bit integer from a SDIO function
 *	@func: SDIO function to access
 *	@addr: address to read
 *	@err_ret: optional status value from transfer
 *
 *	Reads a 16 bit integer from the address space of a given SDIO
 *	function. If there is a problem reading the address, 0xffff
 *	is returned and @err_ret will contain the error code.
 */
u16 sdio_readw(struct sdio_func *func, unsigned int addr, int *err_ret)
{
	int ret;

	ret = sdio_memcpy_fromio(func, func->tmpbuf, addr, 2);
	if (err_ret)
		*err_ret = ret;
	if (ret)
		return 0xFFFF;

	return le16_to_cpup((__le16 *)func->tmpbuf);
}
EXPORT_SYMBOL_GPL(sdio_readw);

/**
 *	sdio_writew - write a 16 bit integer to a SDIO function
 *	@func: SDIO function to access
 *	@b: integer to write
 *	@addr: address to write to
 *	@err_ret: optional status value from transfer
 *
 *	Writes a 16 bit integer to the address space of a given SDIO
 *	function. @err_ret will contain the status of the actual
 *	transfer.
 */
void sdio_writew(struct sdio_func *func, u16 b, unsigned int addr, int *err_ret)
{
	int ret;

	*(__le16 *)func->tmpbuf = cpu_to_le16(b);

	ret = sdio_memcpy_toio(func, addr, func->tmpbuf, 2);
	if (err_ret)
		*err_ret = ret;
}
EXPORT_SYMBOL_GPL(sdio_writew);

/**
 *	sdio_readl - read a 32 bit integer from a SDIO function
 *	@func: SDIO function to access
 *	@addr: address to read
 *	@err_ret: optional status value from transfer
 *
 *	Reads a 32 bit integer from the address space of a given SDIO
 *	function. If there is a problem reading the address,
 *	0xffffffff is returned and @err_ret will contain the error
 *	code.
 */
u32 sdio_readl(struct sdio_func *func, unsigned int addr, int *err_ret)
{
	int ret;

	ret = sdio_memcpy_fromio(func, func->tmpbuf, addr, 4);
	if (err_ret)
		*err_ret = ret;
	if (ret)
		return 0xFFFFFFFF;

	return le32_to_cpup((__le32 *)func->tmpbuf);
}
EXPORT_SYMBOL_GPL(sdio_readl);

/**
 *	sdio_writel - write a 32 bit integer to a SDIO function
 *	@func: SDIO function to access
 *	@b: integer to write
 *	@addr: address to write to
 *	@err_ret: optional status value from transfer
 *
 *	Writes a 32 bit integer to the address space of a given SDIO
 *	function. @err_ret will contain the status of the actual
 *	transfer.
 */
void sdio_writel(struct sdio_func *func, u32 b, unsigned int addr, int *err_ret)
{
	int ret;

	*(__le32 *)func->tmpbuf = cpu_to_le32(b);

	ret = sdio_memcpy_toio(func, addr, func->tmpbuf, 4);
	if (err_ret)
		*err_ret = ret;
}
EXPORT_SYMBOL_GPL(sdio_writel);

/**
 *	sdio_f0_readb - read a single byte from SDIO function 0
 *	@func: an SDIO function of the card
 *	@addr: address to read
 *	@err_ret: optional status value from transfer
 *
 *	Reads a single byte from the address space of SDIO function 0.
 *	If there is a problem reading the address, 0xff is returned
 *	and @err_ret will contain the error code.
 */
unsigned char sdio_f0_readb(struct sdio_func *func, unsigned int addr,
	int *err_ret)
{
	int ret;
	unsigned char val;

	if (!func) {
		if (err_ret)
			*err_ret = -EINVAL;
		return 0xFF;
	}

	ret = mmc_io_rw_direct(func->card, 0, 0, addr, 0, &val);
	if (err_ret)
		*err_ret = ret;
	if (ret)
		return 0xFF;

	return val;
}
EXPORT_SYMBOL_GPL(sdio_f0_readb);

/**
 *	sdio_f0_writeb - write a single byte to SDIO function 0
 *	@func: an SDIO function of the card
 *	@b: byte to write
 *	@addr: address to write to
 *	@err_ret: optional status value from transfer
 *
 *	Writes a single byte to the address space of SDIO function 0.
 *	@err_ret will contain the status of the actual transfer.
 *
 *	Only writes to the vendor specific CCCR registers (0xF0 -
 *	0xFF) are permiited; @err_ret will be set to -EINVAL for *
 *	writes outside this range.
 */
void sdio_f0_writeb(struct sdio_func *func, unsigned char b, unsigned int addr,
	int *err_ret)
{
	int ret;

	if (!func) {
		if (err_ret)
			*err_ret = -EINVAL;
		return;
	}

	if ((addr < 0xF0 || addr > 0xFF) && (!mmc_card_lenient_fn0(func->card))) {
		if (err_ret)
			*err_ret = -EINVAL;
		return;
	}

	ret = mmc_io_rw_direct(func->card, 1, 0, addr, b, NULL);
	if (err_ret)
		*err_ret = ret;
}
EXPORT_SYMBOL_GPL(sdio_f0_writeb);

/**
 *	sdio_get_host_pm_caps - get host power management capabilities
 *	@func: SDIO function attached to host
 *
 *	Returns a capability bitmask corresponding to power management
 *	features supported by the host controller that the card function
 *	might rely upon during a system suspend.  The host doesn't need
 *	to be claimed, nor the function active, for this information to be
 *	obtained.
 */
mmc_pm_flag_t sdio_get_host_pm_caps(struct sdio_func *func)
{
	if (!func)
		return 0;

	return func->card->host->pm_caps;
}
EXPORT_SYMBOL_GPL(sdio_get_host_pm_caps);

/**
 *	sdio_set_host_pm_flags - set wanted host power management capabilities
 *	@func: SDIO function attached to host
 *
 *	Set a capability bitmask corresponding to wanted host controller
 *	power management features for the upcoming suspend state.
 *	This must be called, if needed, each time the suspend method of
 *	the function driver is called, and must contain only bits that
 *	were returned by sdio_get_host_pm_caps().
 *	The host doesn't need to be claimed, nor the function active,
 *	for this information to be set.
 */
int sdio_set_host_pm_flags(struct sdio_func *func, mmc_pm_flag_t flags)
{
	struct mmc_host *host;

	if (!func)
		return -EINVAL;

	host = func->card->host;

	if (flags & ~host->pm_caps)
		return -EINVAL;

	/* function suspend methods are serialized, hence no lock needed */
	host->pm_flags |= flags;
	return 0;
}
EXPORT_SYMBOL_GPL(sdio_set_host_pm_flags);
back to top