[RFC][WORTH IT?][PATCH] bcma: make use of crc8 lib

[RFC][WORTH IT?][PATCH] bcma: make use of crc8 lib

[Rafał Miłecki]

Cc: Arend van Spriel <arend@broadcom.com>
Signed-off-by: Rafa? Mi?ecki <zajec5@gmail.com>
---
We implement crc8 function in bcma, while there is nice lib for this.

The problem is we need to calculate crc8 for SPROM which consists of
u16 entries. So this requires us to do proper convertion to avoid
endianess problems.

Do you think it is worth it? Should we do additional convertion just to
allow using standard library?

Or maybe we should just limit our changes to using crc8_populate_lsb
for generating look up table?
---
 drivers/bcma/Kconfig             |    1 +
 drivers/bcma/sprom.c             |   62 ++++++++++---------------------------
 drivers/net/wireless/b43/Kconfig |    2 +-
 3 files changed, 19 insertions(+), 46 deletions(-)

diff --git a/drivers/bcma/Kconfig b/drivers/bcma/Kconfig
index 83e9adf..4e28fed 100644
--- a/drivers/bcma/Kconfig
+++ b/drivers/bcma/Kconfig
@@ -9,6 +9,7 @@ menu "Broadcom specific AMBA"
 config BCMA
 	tristate "BCMA support"
 	depends on BCMA_POSSIBLE
+	select CRC8
 	help
 	  Bus driver for Broadcom specific Advanced Microcontroller Bus
 	  Architecture.
diff --git a/drivers/bcma/sprom.c b/drivers/bcma/sprom.c
index ffbb0e3..0ad6f01 100644
--- a/drivers/bcma/sprom.c
+++ b/drivers/bcma/sprom.c
@@ -9,6 +9,7 @@
 
 #include <linux/bcma/bcma.h>
 #include <linux/bcma/bcma_regs.h>
+#include <linux/crc8.h>
 #include <linux/pci.h>
 #include <linux/io.h>
 #include <linux/dma-mapping.h>
@@ -32,56 +33,27 @@ static void bcma_sprom_read(struct bcma_bus *bus, u16 *sprom)
  * Validation.
  **************************************************/
 
-static inline u8 bcma_crc8(u8 crc, u8 data)
-{
-	/* Polynomial:   x^8 + x^7 + x^6 + x^4 + x^2 + 1   */
-	static const u8 t[] = {
-		0x00, 0xF7, 0xB9, 0x4E, 0x25, 0xD2, 0x9C, 0x6B,
-		0x4A, 0xBD, 0xF3, 0x04, 0x6F, 0x98, 0xD6, 0x21,
-		0x94, 0x63, 0x2D, 0xDA, 0xB1, 0x46, 0x08, 0xFF,
-		0xDE, 0x29, 0x67, 0x90, 0xFB, 0x0C, 0x42, 0xB5,
-		0x7F, 0x88, 0xC6, 0x31, 0x5A, 0xAD, 0xE3, 0x14,
-		0x35, 0xC2, 0x8C, 0x7B, 0x10, 0xE7, 0xA9, 0x5E,
-		0xEB, 0x1C, 0x52, 0xA5, 0xCE, 0x39, 0x77, 0x80,
-		0xA1, 0x56, 0x18, 0xEF, 0x84, 0x73, 0x3D, 0xCA,
-		0xFE, 0x09, 0x47, 0xB0, 0xDB, 0x2C, 0x62, 0x95,
-		0xB4, 0x43, 0x0D, 0xFA, 0x91, 0x66, 0x28, 0xDF,
-		0x6A, 0x9D, 0xD3, 0x24, 0x4F, 0xB8, 0xF6, 0x01,
-		0x20, 0xD7, 0x99, 0x6E, 0x05, 0xF2, 0xBC, 0x4B,
-		0x81, 0x76, 0x38, 0xCF, 0xA4, 0x53, 0x1D, 0xEA,
-		0xCB, 0x3C, 0x72, 0x85, 0xEE, 0x19, 0x57, 0xA0,
-		0x15, 0xE2, 0xAC, 0x5B, 0x30, 0xC7, 0x89, 0x7E,
-		0x5F, 0xA8, 0xE6, 0x11, 0x7A, 0x8D, 0xC3, 0x34,
-		0xAB, 0x5C, 0x12, 0xE5, 0x8E, 0x79, 0x37, 0xC0,
-		0xE1, 0x16, 0x58, 0xAF, 0xC4, 0x33, 0x7D, 0x8A,
-		0x3F, 0xC8, 0x86, 0x71, 0x1A, 0xED, 0xA3, 0x54,
-		0x75, 0x82, 0xCC, 0x3B, 0x50, 0xA7, 0xE9, 0x1E,
-		0xD4, 0x23, 0x6D, 0x9A, 0xF1, 0x06, 0x48, 0xBF,
-		0x9E, 0x69, 0x27, 0xD0, 0xBB, 0x4C, 0x02, 0xF5,
-		0x40, 0xB7, 0xF9, 0x0E, 0x65, 0x92, 0xDC, 0x2B,
-		0x0A, 0xFD, 0xB3, 0x44, 0x2F, 0xD8, 0x96, 0x61,
-		0x55, 0xA2, 0xEC, 0x1B, 0x70, 0x87, 0xC9, 0x3E,
-		0x1F, 0xE8, 0xA6, 0x51, 0x3A, 0xCD, 0x83, 0x74,
-		0xC1, 0x36, 0x78, 0x8F, 0xE4, 0x13, 0x5D, 0xAA,
-		0x8B, 0x7C, 0x32, 0xC5, 0xAE, 0x59, 0x17, 0xE0,
-		0x2A, 0xDD, 0x93, 0x64, 0x0F, 0xF8, 0xB6, 0x41,
-		0x60, 0x97, 0xD9, 0x2E, 0x45, 0xB2, 0xFC, 0x0B,
-		0xBE, 0x49, 0x07, 0xF0, 0x9B, 0x6C, 0x22, 0xD5,
-		0xF4, 0x03, 0x4D, 0xBA, 0xD1, 0x26, 0x68, 0x9F,
-	};
-	return t[crc ^ data];
-}
-
 static u8 bcma_sprom_crc(const u16 *sprom)
 {
-	int word;
-	u8 crc = 0xFF;
+	u8 crc;
+	u8 sprom2[SSB_SPROMSIZE_WORDS_R4 * 2 - 1];
+	u8 table[CRC8_TABLE_SIZE];
+	u16 word;
 
+	/* u16 to u8 */
 	for (word = 0; word < SSB_SPROMSIZE_WORDS_R4 - 1; word++) {
-		crc = bcma_crc8(crc, sprom[word] & 0x00FF);
-		crc = bcma_crc8(crc, (sprom[word] & 0xFF00) >> 8);
+		sprom2[word * 2] = sprom[word] & 0x00FF;
+		sprom2[(word * 2) + 1] = (sprom[word] & 0xFF00) >> 8;
 	}
-	crc = bcma_crc8(crc, sprom[SSB_SPROMSIZE_WORDS_R4 - 1] & 0x00FF);
+	/* 127th byte */
+	sprom2[(SSB_SPROMSIZE_WORDS_R4 * 2) - 2] =
+				sprom[SSB_SPROMSIZE_WORDS_R4 - 1] & 0x00FF;
+
+	/* Prepare table, 0xAB is x^8 + x^7 + x^6 + x^4 + x^2 + 1 */
+	crc8_populate_lsb(table, 0xAB);
+
+	/* Calculate */
+	crc = crc8(table, sprom2, (SSB_SPROMSIZE_WORDS_R4 * 2) - 1, 0xFF);
 	crc ^= 0xFF;
 
 	return crc;
-- 
1.7.3.4

[RFC][WORTH IT?][PATCH] bcma: make use of crc8 lib

[Rafał Miłecki]

W dniu 15 czerwca 2011 14:09 u?ytkownik Arend van Spriel
<arend@broadcom.com> napisa?:
> On 06/15/2011 01:53 PM, Rafa? Mi?ecki wrote:
>>
>> ?static u8 bcma_sprom_crc(const u16 *sprom)
>> ?{
>> - ? ? ? int word;
>> - ? ? ? u8 crc = 0xFF;
>> + ? ? ? u8 crc;
>> + ? ? ? u8 sprom2[SSB_SPROMSIZE_WORDS_R4 * 2 - 1];
>> + ? ? ? u8 table[CRC8_TABLE_SIZE];
>> + ? ? ? u16 word;
>>
>> + ? ? ? /* u16 to u8 */
>> ? ? ? ?for (word = 0; word< ?SSB_SPROMSIZE_WORDS_R4 - 1; word++) {
>> - ? ? ? ? ? ? ? crc = bcma_crc8(crc, sprom[word]& ?0x00FF);
>> - ? ? ? ? ? ? ? crc = bcma_crc8(crc, (sprom[word]& ?0xFF00)>> ?8);
>> + ? ? ? ? ? ? ? sprom2[word * 2] = sprom[word]& ?0x00FF;
>> + ? ? ? ? ? ? ? sprom2[(word * 2) + 1] = (sprom[word]& ?0xFF00)>> ?8;
>> ? ? ? ?}
>> - ? ? ? crc = bcma_crc8(crc, sprom[SSB_SPROMSIZE_WORDS_R4 - 1]& ?0x00FF);
>> + ? ? ? /* 127th byte */
>> + ? ? ? sprom2[(SSB_SPROMSIZE_WORDS_R4 * 2) - 2] =
>> + ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? sprom[SSB_SPROMSIZE_WORDS_R4 - 1]&
>> ?0x00FF;
>> +
>> + ? ? ? /* Prepare table, 0xAB is x^8 + x^7 + x^6 + x^4 + x^2 + 1 */
>> + ? ? ? crc8_populate_lsb(table, 0xAB);
>> +
>> + ? ? ? /* Calculate */
>> + ? ? ? crc = crc8(table, sprom2, (SSB_SPROMSIZE_WORDS_R4 * 2) - 1, 0xFF);
>> ? ? ? ?crc ^= 0xFF;
>>
>> ? ? ? ?return crc;
>
> You could do (I think):
>
> crc8_populate_lsb(table, 0xAB);
> for (word = 0; word< ?SSB_SPROMSIZE_WORDS_R4; word++) {
> ? ? ? ?u16 val = cpu_to_le16(sprom[word]);
> ? ? ? ?crc = crc8(table,&val, sizeof(u16), crc);
> }

Maybe not a perfect/optimal solution (crc8 focuses on tables, we do
double loop instead) but should work. Thanks for the tip.

-- 
Rafa?