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rtl8180: don't use weird trick to access "far" registers

PATCH In review Andrea Merello 2 participants 3 messages Mar 28, 2014 – Apr 4, 2014 1 message not in the archive Networking drivers (wireless)

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Andrea Merello

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#1 lore raw

PATCH 2/2 rtl8180: don't use weird trick to access "far" registers

In reply to a message not in the archive

In rtl8180/rtl8185/rtl8187se the register space is represented using packed structure type. Register are thus accessed using a pointer of this type.
All registers are packed toghether, and only small gaps are present.

However Rtl8187se has also some "sparse" registers, very far from the "main register block".

It could be possible to access them by simply declare huge reserved blocks inside the register struct (and this causes NO memory waste). However, for various reasons, access to those "far" registers is done with special dedicated macros, without declaring them in the register struct.

This is done in an intricate manner, that makes code less readable and caused static analisys tool to produce warnings.

This patch keeps the "macro" mechanism, but it changes its implementation in a simplier and more straightforward way.

Signed-off-by Andrea Merello <[email protected]>
---
 drivers/net/wireless/rtl818x/rtl818x.h | 14 ++++----------
 1 file changed, 4 insertions(+), 10 deletions(-)
drivers/net/wireless/rtl818x/rtl818x.h +4 -10
index 99dbc12..45ea4e1 100644
@@ -17,13 +17,7 @@
 
 struct rtl818x_csr {
 
-	union {
-		u8	MAC[6];
-		u8	offset1[6];     /* upper page indexing helpers */
-		__le16	offset2[1];
-		__le32	offset4[1];
-	} __packed;
-
+	u8	MAC[6];
 	u8	reserved_0[2];
 
 	union {

@@ -340,9 +334,9 @@ struct rtl818x_csr {
  * I don't like to introduce a ton of "reserved"..
  * They are for RTL8187SE
  */
-#define REG_ADDR1(addr)	((u8 __iomem *)(&priv->map->offset1[(addr)]))
-#define REG_ADDR2(addr)	((__le16 __iomem *)(&priv->map->offset2[((addr) >> 1)]))
-#define REG_ADDR4(addr)	((__le32 __iomem *)(&priv->map->offset4[((addr) >> 2)]))
+#define REG_ADDR1(addr)	((u8 __iomem *)priv->map + addr)
+#define REG_ADDR2(addr)	((__le16 __iomem *)priv->map + (addr >> 1))
+#define REG_ADDR4(addr)	((__le32 __iomem *)priv->map + (addr >> 2))
 
 #define FEMR_SE		REG_ADDR2(0x1D4)
 #define ARFR		REG_ADDR2(0x1E0)
Signature · 1 line
1.8.3.2
#2 lore raw

drivers/net/wireless/rtl818x/rtl818x.h struct rtl818x_csr { · line 342

Quoted 13 lines · Andrea Merello
drivers/net/wireless/rtl818x/rtl818x.h +3 -3
@@ -340,9 +334,9 @@ struct rtl818x_csr {
   * I don't like to introduce a ton of "reserved"..
   * They are for RTL8187SE
   */
-#define REG_ADDR1(addr)	((u8 __iomem *)(&priv->map->offset1[(addr)]))
-#define REG_ADDR2(addr)	((__le16 __iomem *)(&priv->map->offset2[((addr) >> 1)]))
-#define REG_ADDR4(addr)	((__le32 __iomem *)(&priv->map->offset4[((addr) >> 2)]))
+#define REG_ADDR1(addr)	((u8 __iomem *)priv->map + addr)
+#define REG_ADDR2(addr)	((__le16 __iomem *)priv->map + (addr >> 1))
+#define REG_ADDR4(addr)	((__le32 __iomem *)priv->map + (addr >> 2))
 
  #define FEMR_SE		REG_ADDR2(0x1D4)
  #define ARFR		REG_ADDR2(0x1E0)

I suggest parenthesizing the use of addr in your macros (as the original code does), to avoid any issues with operator precedence wrt >>.

If the removal was intentional and you've verified there's no issues, you should probably mention it in the commit message.

Dave.

author
#3 lore raw

PATCH 3/4 rtl8180: add parentheses to REG_ADDR macros

Parentheses are missing around the macro argument, causing the macro possibly not to work passing certain expressions as arguments.

This should not cause any issues with current code, however it's worth to add them, as a good practice, and to eventually avoid future bugs.

Suggested-by Dave Kilroy <[email protected]>
Signed-off-by Andrea Merello <[email protected]>
---
 drivers/net/wireless/rtl818x/rtl818x.h | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)
drivers/net/wireless/rtl818x/rtl818x.h +3 -3
index 45ea4e1..7abef95 100644
@@ -334,9 +334,9 @@ struct rtl818x_csr {
  * I don't like to introduce a ton of "reserved"..
  * They are for RTL8187SE
  */
-#define REG_ADDR1(addr)	((u8 __iomem *)priv->map + addr)
-#define REG_ADDR2(addr)	((__le16 __iomem *)priv->map + (addr >> 1))
-#define REG_ADDR4(addr)	((__le32 __iomem *)priv->map + (addr >> 2))
+#define REG_ADDR1(addr)	((u8 __iomem *)priv->map + (addr))
+#define REG_ADDR2(addr)	((__le16 __iomem *)priv->map + ((addr) >> 1))
+#define REG_ADDR4(addr)	((__le32 __iomem *)priv->map + ((addr) >> 2))
 
 #define FEMR_SE		REG_ADDR2(0x1D4)
 #define ARFR		REG_ADDR2(0x1E0)
Signature · 1 line
1.8.3.2