PCI: rewrite PCI BAR reading code

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>

1 files changed, 123 insertions, 119 deletions

diff --git a/drivers/pci/probe.c b/drivers/pci/probe.c
index b1724cf31b66..3b690c3512f3 100644
--- a/drivers/pci/probe.c
+++ b/drivers/pci/probe.c
@@ -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);
         }
 }