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Date: Tue, 23 Dec 2008 22:59:38 +0100
From: Michał Mirosław <mirq-linux@...e.qmqm.pl>
To: linux-kernel@...r.kernel.org, linux-pci@...r.kernel.org
Subject: RFC: pci_write_bits*() convenience functions
There are a lot of code fragments in kernel looking like this:
u16 buf;
pci_read_config_word(pdev, offset, &buf);
buf &= ~mask;
buf |= value;
pci_write_config_word(pdev, offset, buf);
In in-kernel EDAC sources I found an implementation of pci_write_bits*()
that allows above 5 lines to be easily converted to:
pci_write_bits16(pdev, offset, value, mask);
Since this sequence is common while initializing a device or sometimes
during its normal operation I even wrote similar wrappers (see: driver
for CB710 memory card reader, posted about a month ago to LKML and
MMC mailinglists). I guess that there are more people hiding that
could use this.
This patch moves functions mentioned above to global include: linux/pci.h.
I verified that no users in EDAC code rely on the mask != (u16)(-1) test
and I think that plain pci_write_config_X() is better in cases where
this test is known to evaluate to false.
What's interesting, there are 2039 lines where pci_read_config_*() is used
and in only about 161 the return value is checked (as of current linux-2.6.git
tree: commit 3d44cc3e01..., quick grep test).
Best Regards,
Michał Mirosław
(Please Cc: me on reply to list.)
diff --git a/drivers/edac/edac_core.h b/drivers/edac/edac_core.h
index 4b55ec6..f1f8b94 100644
--- a/drivers/edac/edac_core.h
+++ b/drivers/edac/edac_core.h
@@ -722,54 +722,6 @@ struct edac_pci_ctl_info {
#define to_edac_pci_ctl_work(w) \
container_of(w, struct edac_pci_ctl_info,work)
-/* write all or some bits in a byte-register*/
-static inline void pci_write_bits8(struct pci_dev *pdev, int offset, u8 value,
- u8 mask)
-{
- if (mask != 0xff) {
- u8 buf;
-
- pci_read_config_byte(pdev, offset, &buf);
- value &= mask;
- buf &= ~mask;
- value |= buf;
- }
-
- pci_write_config_byte(pdev, offset, value);
-}
-
-/* write all or some bits in a word-register*/
-static inline void pci_write_bits16(struct pci_dev *pdev, int offset,
- u16 value, u16 mask)
-{
- if (mask != 0xffff) {
- u16 buf;
-
- pci_read_config_word(pdev, offset, &buf);
- value &= mask;
- buf &= ~mask;
- value |= buf;
- }
-
- pci_write_config_word(pdev, offset, value);
-}
-
-/* write all or some bits in a dword-register*/
-static inline void pci_write_bits32(struct pci_dev *pdev, int offset,
- u32 value, u32 mask)
-{
- if (mask != 0xffff) {
- u32 buf;
-
- pci_read_config_dword(pdev, offset, &buf);
- value &= mask;
- buf &= ~mask;
- value |= buf;
- }
-
- pci_write_config_dword(pdev, offset, value);
-}
-
#endif /* CONFIG_PCI */
extern struct mem_ctl_info *edac_mc_alloc(unsigned sz_pvt, unsigned nr_csrows,
diff --git a/include/linux/pci.h b/include/linux/pci.h
index feb4657..f9ee511 100644
--- a/include/linux/pci.h
+++ b/include/linux/pci.h
@@ -610,6 +610,22 @@ static inline int pci_write_config_dword(struct pci_dev *dev, int where,
return pci_bus_write_config_dword(dev->bus, dev->devfn, where, val);
}
+#define GEN_PCI_UPDATE_FUNC(t,b) \
+static inline void pci_write_bits##b(struct pci_dev *dev, int where, \
+ u##b value, u##b mask) \
+{ \
+ u##b buf; \
+ \
+ pci_read_config_##t(dev, where, &buf); \
+ buf &= ~mask; \
+ buf |= value; \
+ pci_write_config_##t(dev, where, buf); \
+}
+GEN_PCI_UPDATE_FUNC(byte,8)
+GEN_PCI_UPDATE_FUNC(word,16)
+GEN_PCI_UPDATE_FUNC(dword,32)
+#undef GEN_PCI_UPDATE_FUNC
+
int __must_check pci_enable_device(struct pci_dev *dev);
int __must_check pci_enable_device_io(struct pci_dev *dev);
int __must_check pci_enable_device_mem(struct pci_dev *dev);
--
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