PCI: rewrite PCI BAR reading code
Matthew Wilcox [Mon, 28 Jul 2008 17:38:59 +0000 (13:38 -0400)]
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>

drivers/pci/probe.c

index b1724cf..3b690c3 100644 (file)
@@ -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;
 
@@ -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);
        }
 }