[PATCH 5/5] misc: atsha204a: Remove duplicate CRC-16 implementation

Thu Apr 21 16:35:33 CEST 2022

On 4/12/22 11:20, Pali Rohár wrote:
> ATSHA204A uses bit-reversed checksum of standard CRC-16 with polynomial
> x^16 + x^15 + x^2 + 1.
> 
> This ATSHA204A specific checksum can be calculated just by using common
> U-Boot functions bitrev16() and crc16().
> 
> So replace custom driver CRC-16 implementation by common U-Boot functions.
> 
> Signed-off-by: Pali Rohár <pali at kernel.org>

Reviewed-by: Stefan Roese <sr at denx.de>

Thanks,
Stefan

> ---
>   drivers/misc/Kconfig         |   1 +
>   drivers/misc/atsha204a-i2c.c | 122 +----------------------------------
>   2 files changed, 4 insertions(+), 119 deletions(-)
> 
> diff --git a/drivers/misc/Kconfig b/drivers/misc/Kconfig
> index 7029bb7b5c58..95bb678a6635 100644
> --- a/drivers/misc/Kconfig
> +++ b/drivers/misc/Kconfig
> @@ -40,6 +40,7 @@ config ALTERA_SYSID
>   
>   config ATSHA204A
>   	bool "Support for Atmel ATSHA204A module"
> +	select BITREVERSE
>   	depends on MISC
>   	help
>   	   Enable support for I2C connected Atmel's ATSHA204A
> diff --git a/drivers/misc/atsha204a-i2c.c b/drivers/misc/atsha204a-i2c.c
> index 8b0055f99893..aa6acf0f9a0e 100644
> --- a/drivers/misc/atsha204a-i2c.c
> +++ b/drivers/misc/atsha204a-i2c.c
> @@ -18,6 +18,7 @@
>   #include <log.h>
>   #include <asm/global_data.h>
>   #include <linux/delay.h>
> +#include <linux/bitrev.h>
>   #include <u-boot/crc.h>
>   
>   #define ATSHA204A_TWLO			60
> @@ -27,126 +28,9 @@
>   
>   DECLARE_GLOBAL_DATA_PTR;
>   
> -/*
> - * The ATSHA204A uses an (to me) unknown CRC-16 algorithm.
> - * The Reveng CRC-16 catalogue does not contain it.
> - *
> - * Because in Atmel's documentation only a primitive implementation
> - * can be found, I have implemented this one with lookup table.
> - */
> -
> -/*
> - * This is the code that computes the table below:
> - *
> - * int i, j;
> - * for (i = 0; i < 256; ++i) {
> - *	u8 c = 0;
> - *	for (j = 0; j < 8; ++j) {
> - *		c = (c << 1) | ((i >> j) & 1);
> - *	}
> - *	bitreverse_table[i] = c;
> - * }
> - */
> -
> -static u8 const bitreverse_table[256] = {
> -	0x00, 0x80, 0x40, 0xc0, 0x20, 0xa0, 0x60, 0xe0,
> -	0x10, 0x90, 0x50, 0xd0, 0x30, 0xb0, 0x70, 0xf0,
> -	0x08, 0x88, 0x48, 0xc8, 0x28, 0xa8, 0x68, 0xe8,
> -	0x18, 0x98, 0x58, 0xd8, 0x38, 0xb8, 0x78, 0xf8,
> -	0x04, 0x84, 0x44, 0xc4, 0x24, 0xa4, 0x64, 0xe4,
> -	0x14, 0x94, 0x54, 0xd4, 0x34, 0xb4, 0x74, 0xf4,
> -	0x0c, 0x8c, 0x4c, 0xcc, 0x2c, 0xac, 0x6c, 0xec,
> -	0x1c, 0x9c, 0x5c, 0xdc, 0x3c, 0xbc, 0x7c, 0xfc,
> -	0x02, 0x82, 0x42, 0xc2, 0x22, 0xa2, 0x62, 0xe2,
> -	0x12, 0x92, 0x52, 0xd2, 0x32, 0xb2, 0x72, 0xf2,
> -	0x0a, 0x8a, 0x4a, 0xca, 0x2a, 0xaa, 0x6a, 0xea,
> -	0x1a, 0x9a, 0x5a, 0xda, 0x3a, 0xba, 0x7a, 0xfa,
> -	0x06, 0x86, 0x46, 0xc6, 0x26, 0xa6, 0x66, 0xe6,
> -	0x16, 0x96, 0x56, 0xd6, 0x36, 0xb6, 0x76, 0xf6,
> -	0x0e, 0x8e, 0x4e, 0xce, 0x2e, 0xae, 0x6e, 0xee,
> -	0x1e, 0x9e, 0x5e, 0xde, 0x3e, 0xbe, 0x7e, 0xfe,
> -	0x01, 0x81, 0x41, 0xc1, 0x21, 0xa1, 0x61, 0xe1,
> -	0x11, 0x91, 0x51, 0xd1, 0x31, 0xb1, 0x71, 0xf1,
> -	0x09, 0x89, 0x49, 0xc9, 0x29, 0xa9, 0x69, 0xe9,
> -	0x19, 0x99, 0x59, 0xd9, 0x39, 0xb9, 0x79, 0xf9,
> -	0x05, 0x85, 0x45, 0xc5, 0x25, 0xa5, 0x65, 0xe5,
> -	0x15, 0x95, 0x55, 0xd5, 0x35, 0xb5, 0x75, 0xf5,
> -	0x0d, 0x8d, 0x4d, 0xcd, 0x2d, 0xad, 0x6d, 0xed,
> -	0x1d, 0x9d, 0x5d, 0xdd, 0x3d, 0xbd, 0x7d, 0xfd,
> -	0x03, 0x83, 0x43, 0xc3, 0x23, 0xa3, 0x63, 0xe3,
> -	0x13, 0x93, 0x53, 0xd3, 0x33, 0xb3, 0x73, 0xf3,
> -	0x0b, 0x8b, 0x4b, 0xcb, 0x2b, 0xab, 0x6b, 0xeb,
> -	0x1b, 0x9b, 0x5b, 0xdb, 0x3b, 0xbb, 0x7b, 0xfb,
> -	0x07, 0x87, 0x47, 0xc7, 0x27, 0xa7, 0x67, 0xe7,
> -	0x17, 0x97, 0x57, 0xd7, 0x37, 0xb7, 0x77, 0xf7,
> -	0x0f, 0x8f, 0x4f, 0xcf, 0x2f, 0xaf, 0x6f, 0xef,
> -	0x1f, 0x9f, 0x5f, 0xdf, 0x3f, 0xbf, 0x7f, 0xff,
> -};
> -
> -/*
> - * This is the code that computes the table below:
> - *
> - * int i, j;
> - * for (i = 0; i < 256; ++i) {
> - *	u16 c = i << 8;
> - *	for (j = 0; j < 8; ++j) {
> - *		int b = c >> 15;
> - *		c <<= 1;
> - *		if (b)
> - *			c ^= 0x8005;
> - *	}
> - *	crc16_table[i] = c;
> - * }
> - */
> -static u16 const crc16_table[256] = {
> -	0x0000, 0x8005, 0x800f, 0x000a, 0x801b, 0x001e, 0x0014, 0x8011,
> -	0x8033, 0x0036, 0x003c, 0x8039, 0x0028, 0x802d, 0x8027, 0x0022,
> -	0x8063, 0x0066, 0x006c, 0x8069, 0x0078, 0x807d, 0x8077, 0x0072,
> -	0x0050, 0x8055, 0x805f, 0x005a, 0x804b, 0x004e, 0x0044, 0x8041,
> -	0x80c3, 0x00c6, 0x00cc, 0x80c9, 0x00d8, 0x80dd, 0x80d7, 0x00d2,
> -	0x00f0, 0x80f5, 0x80ff, 0x00fa, 0x80eb, 0x00ee, 0x00e4, 0x80e1,
> -	0x00a0, 0x80a5, 0x80af, 0x00aa, 0x80bb, 0x00be, 0x00b4, 0x80b1,
> -	0x8093, 0x0096, 0x009c, 0x8099, 0x0088, 0x808d, 0x8087, 0x0082,
> -	0x8183, 0x0186, 0x018c, 0x8189, 0x0198, 0x819d, 0x8197, 0x0192,
> -	0x01b0, 0x81b5, 0x81bf, 0x01ba, 0x81ab, 0x01ae, 0x01a4, 0x81a1,
> -	0x01e0, 0x81e5, 0x81ef, 0x01ea, 0x81fb, 0x01fe, 0x01f4, 0x81f1,
> -	0x81d3, 0x01d6, 0x01dc, 0x81d9, 0x01c8, 0x81cd, 0x81c7, 0x01c2,
> -	0x0140, 0x8145, 0x814f, 0x014a, 0x815b, 0x015e, 0x0154, 0x8151,
> -	0x8173, 0x0176, 0x017c, 0x8179, 0x0168, 0x816d, 0x8167, 0x0162,
> -	0x8123, 0x0126, 0x012c, 0x8129, 0x0138, 0x813d, 0x8137, 0x0132,
> -	0x0110, 0x8115, 0x811f, 0x011a, 0x810b, 0x010e, 0x0104, 0x8101,
> -	0x8303, 0x0306, 0x030c, 0x8309, 0x0318, 0x831d, 0x8317, 0x0312,
> -	0x0330, 0x8335, 0x833f, 0x033a, 0x832b, 0x032e, 0x0324, 0x8321,
> -	0x0360, 0x8365, 0x836f, 0x036a, 0x837b, 0x037e, 0x0374, 0x8371,
> -	0x8353, 0x0356, 0x035c, 0x8359, 0x0348, 0x834d, 0x8347, 0x0342,
> -	0x03c0, 0x83c5, 0x83cf, 0x03ca, 0x83db, 0x03de, 0x03d4, 0x83d1,
> -	0x83f3, 0x03f6, 0x03fc, 0x83f9, 0x03e8, 0x83ed, 0x83e7, 0x03e2,
> -	0x83a3, 0x03a6, 0x03ac, 0x83a9, 0x03b8, 0x83bd, 0x83b7, 0x03b2,
> -	0x0390, 0x8395, 0x839f, 0x039a, 0x838b, 0x038e, 0x0384, 0x8381,
> -	0x0280, 0x8285, 0x828f, 0x028a, 0x829b, 0x029e, 0x0294, 0x8291,
> -	0x82b3, 0x02b6, 0x02bc, 0x82b9, 0x02a8, 0x82ad, 0x82a7, 0x02a2,
> -	0x82e3, 0x02e6, 0x02ec, 0x82e9, 0x02f8, 0x82fd, 0x82f7, 0x02f2,
> -	0x02d0, 0x82d5, 0x82df, 0x02da, 0x82cb, 0x02ce, 0x02c4, 0x82c1,
> -	0x8243, 0x0246, 0x024c, 0x8249, 0x0258, 0x825d, 0x8257, 0x0252,
> -	0x0270, 0x8275, 0x827f, 0x027a, 0x826b, 0x026e, 0x0264, 0x8261,
> -	0x0220, 0x8225, 0x822f, 0x022a, 0x823b, 0x023e, 0x0234, 0x8231,
> -	0x8213, 0x0216, 0x021c, 0x8219, 0x0208, 0x820d, 0x8207, 0x0202,
> -};
> -
> -static inline u16 crc16_byte(u16 crc, const u8 data)
> +static inline u16 atsha204a_crc16(const u8 *buffer, size_t len)
>   {
> -	u16 t = crc16_table[((crc >> 8) ^ bitreverse_table[data]) & 0xff];
> -	return ((crc << 8) ^ t);
> -}
> -
> -static u16 atsha204a_crc16(const u8 *buffer, size_t len)
> -{
> -	u16 crc = 0;
> -
> -	while (len--)
> -		crc = crc16_byte(crc, *buffer++);
> -
> -	return crc;
> +	return bitrev16(crc16(0, buffer, len));
>   }
>   
>   static int atsha204a_send(struct udevice *dev, const u8 *buf, u8 len)

Viele Grüße,
Stefan Roese

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