[PATCH v2] PCI/VPD: Use unaligned access helpers in pci_vpd_read

[Heiner Kallweit <hkallweit1@xxxxxxxxx>]

With this patch we avoid some unnecessary looping if the platform defines
HAVE_EFFICIENT_UNALIGNED_ACCESS and we make the code better readable.
No functional change intended.

Signed-off-by: Heiner Kallweit <hkallweit1@xxxxxxxxx>
---
v2: remove not needed tmpbuf variable
---
 drivers/pci/vpd.c | 22 ++++++++++++----------
 1 file changed, 12 insertions(+), 10 deletions(-)

diff --git a/drivers/pci/vpd.c b/drivers/pci/vpd.c
index 741e7a505..ab886e5f4 100644
--- a/drivers/pci/vpd.c
+++ b/drivers/pci/vpd.c
@@ -163,12 +163,11 @@ static int pci_vpd_wait(struct pci_dev *dev)
 }
 
 static ssize_t pci_vpd_read(struct pci_dev *dev, loff_t pos, size_t count,
-			    void *arg)
+			    void *buf)
 {
 	struct pci_vpd *vpd = dev->vpd;
 	int ret;
 	loff_t end = pos + count;
-	u8 *buf = arg;
 
 	if (pos < 0)
 		return -EINVAL;
@@ -197,8 +196,8 @@ static ssize_t pci_vpd_read(struct pci_dev *dev, loff_t pos, size_t count,
 		goto out;
 
 	while (pos < end) {
+		unsigned int len, skip;
 		u32 val;
-		unsigned int i, skip;
 
 		ret = pci_user_write_config_word(dev, vpd->cap + PCI_VPD_ADDR,
 						 pos & ~3);
@@ -215,14 +214,17 @@ static ssize_t pci_vpd_read(struct pci_dev *dev, loff_t pos, size_t count,
 			break;
 
 		skip = pos & 3;
-		for (i = 0;  i < sizeof(u32); i++) {
-			if (i >= skip) {
-				*buf++ = val;
-				if (++pos == end)
-					break;
-			}
-			val >>= 8;
+		len = min_t(unsigned int, 4 - skip, end - pos);
+
+		if (len == 4)  {
+			put_unaligned_le32(val, buf);
+		} else {
+			cpu_to_le32s(&val);
+			memcpy(buf, (u8 *)&val + skip, len);
 		}
+
+		buf += len;
+		pos += len;
 	}
 out:
 	mutex_unlock(&vpd->lock);
-- 
2.31.1