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PCI: rewrite PCI BAR reading code
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Factor out the code to read one BAR from the loop in pci_read_bases into
a new function, __pci_read_base.  The new code is slightly more
readable, better commented and removes the ifdef.

Signed-off-by: Matthew Wilcox <willy@linux.intel.com>
Signed-off-by: Jesse Barnes <jbarnes@virtuousgeek.org>
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Matthew Wilcox authored and Jesse Barnes committed Jul 28, 2008
1 parent 3713907 commit 6ac665c
Showing 1 changed file with 123 additions and 119 deletions.
242 changes: 123 additions & 119 deletions drivers/pci/probe.c
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Original file line number Diff line number Diff line change
Expand Up @@ -163,12 +163,9 @@ static inline unsigned int pci_calc_resource_flags(unsigned int flags)
return IORESOURCE_MEM;
}

/*
* Find the extent of a PCI decode..
*/
static u32 pci_size(u32 base, u32 maxbase, u32 mask)
static u64 pci_size(u64 base, u64 maxbase, u64 mask)
{
u32 size = mask & maxbase; /* Find the significant bits */
u64 size = mask & maxbase; /* Find the significant bits */
if (!size)
return 0;

Expand All @@ -184,135 +181,142 @@ static u32 pci_size(u32 base, u32 maxbase, u32 mask)
return size;
}

static u64 pci_size64(u64 base, u64 maxbase, u64 mask)
{
u64 size = mask & maxbase; /* Find the significant bits */
if (!size)
return 0;
enum pci_bar_type {
pci_bar_unknown, /* Standard PCI BAR probe */
pci_bar_io, /* An io port BAR */
pci_bar_mem32, /* A 32-bit memory BAR */
pci_bar_mem64, /* A 64-bit memory BAR */
};

/* Get the lowest of them to find the decode size, and
from that the extent. */
size = (size & ~(size-1)) - 1;
static inline enum pci_bar_type decode_bar(struct resource *res, u32 bar)
{
if ((bar & PCI_BASE_ADDRESS_SPACE) == PCI_BASE_ADDRESS_SPACE_IO) {
res->flags = bar & ~PCI_BASE_ADDRESS_IO_MASK;
return pci_bar_io;
}

/* base == maxbase can be valid only if the BAR has
already been programmed with all 1s. */
if (base == maxbase && ((base | size) & mask) != mask)
return 0;
res->flags = bar & ~PCI_BASE_ADDRESS_MEM_MASK;

return size;
if (res->flags == PCI_BASE_ADDRESS_MEM_TYPE_64)
return pci_bar_mem64;
return pci_bar_mem32;
}

static inline int is_64bit_memory(u32 mask)
/*
* If the type is not unknown, we assume that the lowest bit is 'enable'.
* Returns 1 if the BAR was 64-bit and 0 if it was 32-bit.
*/
static int __pci_read_base(struct pci_dev *dev, enum pci_bar_type type,
struct resource *res, unsigned int pos)
{
if ((mask & (PCI_BASE_ADDRESS_SPACE|PCI_BASE_ADDRESS_MEM_TYPE_MASK)) ==
(PCI_BASE_ADDRESS_SPACE_MEMORY|PCI_BASE_ADDRESS_MEM_TYPE_64))
return 1;
return 0;
}
u32 l, sz, mask;

static void pci_read_bases(struct pci_dev *dev, unsigned int howmany, int rom)
{
unsigned int pos, reg, next;
u32 l, sz;
struct resource *res;
mask = type ? ~PCI_ROM_ADDRESS_ENABLE : ~0;

for(pos=0; pos<howmany; pos = next) {
u64 l64;
u64 sz64;
u32 raw_sz;
res->name = pci_name(dev);

next = pos+1;
res = &dev->resource[pos];
res->name = pci_name(dev);
reg = PCI_BASE_ADDRESS_0 + (pos << 2);
pci_read_config_dword(dev, reg, &l);
pci_write_config_dword(dev, reg, ~0);
pci_read_config_dword(dev, reg, &sz);
pci_write_config_dword(dev, reg, l);
if (!sz || sz == 0xffffffff)
continue;
if (l == 0xffffffff)
l = 0;
raw_sz = sz;
if ((l & PCI_BASE_ADDRESS_SPACE) ==
PCI_BASE_ADDRESS_SPACE_MEMORY) {
sz = pci_size(l, sz, (u32)PCI_BASE_ADDRESS_MEM_MASK);
/*
* For 64bit prefetchable memory sz could be 0, if the
* real size is bigger than 4G, so we need to check
* szhi for that.
*/
if (!is_64bit_memory(l) && !sz)
continue;
res->start = l & PCI_BASE_ADDRESS_MEM_MASK;
res->flags |= l & ~PCI_BASE_ADDRESS_MEM_MASK;
pci_read_config_dword(dev, pos, &l);
pci_write_config_dword(dev, pos, mask);
pci_read_config_dword(dev, pos, &sz);
pci_write_config_dword(dev, pos, l);

/*
* All bits set in sz means the device isn't working properly.
* If the BAR isn't implemented, all bits must be 0. If it's a
* memory BAR or a ROM, bit 0 must be clear; if it's an io BAR, bit
* 1 must be clear.
*/
if (!sz || sz == 0xffffffff)
goto fail;

/*
* I don't know how l can have all bits set. Copied from old code.
* Maybe it fixes a bug on some ancient platform.
*/
if (l == 0xffffffff)
l = 0;

if (type == pci_bar_unknown) {
type = decode_bar(res, l);
res->flags |= pci_calc_resource_flags(l) | IORESOURCE_SIZEALIGN;
if (type == pci_bar_io) {
l &= PCI_BASE_ADDRESS_IO_MASK;
mask = PCI_BASE_ADDRESS_IO_MASK & 0xffff;
} else {
sz = pci_size(l, sz, PCI_BASE_ADDRESS_IO_MASK & 0xffff);
if (!sz)
continue;
res->start = l & PCI_BASE_ADDRESS_IO_MASK;
res->flags |= l & ~PCI_BASE_ADDRESS_IO_MASK;
l &= PCI_BASE_ADDRESS_MEM_MASK;
mask = (u32)PCI_BASE_ADDRESS_MEM_MASK;
}
res->end = res->start + (unsigned long) sz;
res->flags |= pci_calc_resource_flags(l) | IORESOURCE_SIZEALIGN;
if (is_64bit_memory(l)) {
u32 szhi, lhi;

pci_read_config_dword(dev, reg+4, &lhi);
pci_write_config_dword(dev, reg+4, ~0);
pci_read_config_dword(dev, reg+4, &szhi);
pci_write_config_dword(dev, reg+4, lhi);
sz64 = ((u64)szhi << 32) | raw_sz;
l64 = ((u64)lhi << 32) | l;
sz64 = pci_size64(l64, sz64, PCI_BASE_ADDRESS_MEM_MASK);
next++;
#if BITS_PER_LONG == 64
if (!sz64) {
res->start = 0;
res->end = 0;
res->flags = 0;
continue;
}
res->start = l64 & PCI_BASE_ADDRESS_MEM_MASK;
res->end = res->start + sz64;
#else
if (sz64 > 0x100000000ULL) {
dev_err(&dev->dev, "BAR %d: can't handle 64-bit"
" BAR\n", pos);
res->start = 0;
res->flags = 0;
} else if (lhi) {
/* 64-bit wide address, treat as disabled */
pci_write_config_dword(dev, reg,
l & ~(u32)PCI_BASE_ADDRESS_MEM_MASK);
pci_write_config_dword(dev, reg+4, 0);
res->start = 0;
res->end = sz;
}
#endif
} else {
res->flags |= (l & IORESOURCE_ROM_ENABLE);
l &= PCI_ROM_ADDRESS_MASK;
mask = (u32)PCI_ROM_ADDRESS_MASK;
}

if (type == pci_bar_mem64) {
u64 l64 = l;
u64 sz64 = sz;
u64 mask64 = mask | (u64)~0 << 32;

pci_read_config_dword(dev, pos + 4, &l);
pci_write_config_dword(dev, pos + 4, ~0);
pci_read_config_dword(dev, pos + 4, &sz);
pci_write_config_dword(dev, pos + 4, l);

l64 |= ((u64)l << 32);
sz64 |= ((u64)sz << 32);

sz64 = pci_size(l64, sz64, mask64);

if (!sz64)
goto fail;

if ((BITS_PER_LONG < 64) && (sz64 > 0x100000000ULL)) {
dev_err(&dev->dev, "can't handle 64-bit BAR\n");
goto fail;
} else if ((BITS_PER_LONG < 64) && l) {
/* Address above 32-bit boundary; disable the BAR */
pci_write_config_dword(dev, pos, 0);
pci_write_config_dword(dev, pos + 4, 0);
res->start = 0;
res->end = sz64;
} else {
res->start = l64;
res->end = l64 + sz64;
}
} else {
sz = pci_size(l, sz, mask);

if (!sz)
goto fail;

res->start = l;
res->end = l + sz;
}

out:
return (type == pci_bar_mem64) ? 1 : 0;
fail:
res->flags = 0;
goto out;
}

static void pci_read_bases(struct pci_dev *dev, unsigned int howmany, int rom)
{
unsigned int pos, reg;

for (pos = 0; pos < howmany; pos++) {
struct resource *res = &dev->resource[pos];
reg = PCI_BASE_ADDRESS_0 + (pos << 2);
pos += __pci_read_base(dev, pci_bar_unknown, res, reg);
}

if (rom) {
struct resource *res = &dev->resource[PCI_ROM_RESOURCE];
dev->rom_base_reg = rom;
res = &dev->resource[PCI_ROM_RESOURCE];
res->name = pci_name(dev);
pci_read_config_dword(dev, rom, &l);
pci_write_config_dword(dev, rom, ~PCI_ROM_ADDRESS_ENABLE);
pci_read_config_dword(dev, rom, &sz);
pci_write_config_dword(dev, rom, l);
if (l == 0xffffffff)
l = 0;
if (sz && sz != 0xffffffff) {
sz = pci_size(l, sz, (u32)PCI_ROM_ADDRESS_MASK);
if (sz) {
res->flags = (l & IORESOURCE_ROM_ENABLE) |
IORESOURCE_MEM | IORESOURCE_PREFETCH |
IORESOURCE_READONLY | IORESOURCE_CACHEABLE |
IORESOURCE_SIZEALIGN;
res->start = l & PCI_ROM_ADDRESS_MASK;
res->end = res->start + (unsigned long) sz;
}
}
res->flags = IORESOURCE_MEM | IORESOURCE_PREFETCH |
IORESOURCE_READONLY | IORESOURCE_CACHEABLE |
IORESOURCE_SIZEALIGN;
__pci_read_base(dev, pci_bar_mem32, res, rom);
}
}

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