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Commit 0a25e4d5 authored by Evgeniy Polyakov's avatar Evgeniy Polyakov Committed by Greg Kroah-Hartman
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[PATCH] w1_ds2433: Added crc16 protection and read caching. 



The changes to ds2433 to add CRC16 protection and read caching.

Signed-off-by: default avatarBen Gardner <bgardner@wabtec.com>
Signed-off-by: default avatarEvgeniy Polyakov <johnpol@2ka.mipt.ru>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@suse.de>
parent a45f105a

drivers/w1/Kconfig

+9 −0
Original line number Diff line number Diff line
@@ -61,4 +61,13 @@ config W1_DS2433 
	  Say Y here if you want to use a 1-wire

	  4kb EEPROM family device (DS2433).



config W1_DS2433_CRC

	bool "Protect DS2433 data with a CRC16"

	depends on W1_DS2433

	select CRC16

	help

	  Say Y here to protect DS2433 data with a CRC16.

	  Each block has 30 bytes of data and a two byte CRC16.

	  Full block writes are only allowed if the CRC is valid.



endmenu

drivers/w1/Makefile

+5 −1
Original line number Diff line number Diff line
@@ -6,6 +6,10 @@ ifneq ($(CONFIG_NET), y) 
EXTRA_CFLAGS	+= -DNETLINK_DISABLED

endif



ifeq ($(CONFIG_W1_DS2433_CRC), y)

EXTRA_CFLAGS	+= -DCONFIG_W1_F23_CRC

endif



obj-$(CONFIG_W1)	+= wire.o

wire-objs		:= w1.o w1_int.o w1_family.o w1_netlink.o w1_io.o

drivers/w1/w1_ds2433.c

+111 −6
Original line number Diff line number Diff line
@@ -3,9 +3,8 @@ 
 *

 * Copyright (c) 2005 Ben Gardner <bgardner@wabtec.com>

 *

 * This program is free software; you can redistribute it and/or modify

 * it under the smems of the GNU General Public License as published by

 * the Free Software Foundation; version 2 of the License.

 * This source code is licensed under the GNU General Public License,

 * Version 2. See the file COPYING for more details.

 */



#include <linux/kernel.h>
@@ -14,6 +13,9 @@ 
#include <linux/device.h>

#include <linux/types.h>

#include <linux/delay.h>

#ifdef CONFIG_W1_F23_CRC

#include <linux/crc16.h>

#endif



#include "w1.h"

#include "w1_io.h"
@@ -25,18 +27,26 @@ MODULE_AUTHOR("Ben Gardner <bgardner@wabtec.com>"); 
MODULE_DESCRIPTION("w1 family 23 driver for DS2433, 4kb EEPROM");



#define W1_EEPROM_SIZE		512

#define W1_PAGE_COUNT		16

#define W1_PAGE_SIZE		32

#define W1_PAGE_BITS		5

#define W1_PAGE_MASK		0x1F



#define W1_F23_TIME		300



#define W1_F23_READ_EEPROM	0xF0

#define W1_F23_WRITE_SCRATCH	0x0F

#define W1_F23_READ_SCRATCH	0xAA

#define W1_F23_COPY_SCRATCH	0x55



struct w1_f23_data {

	u8	memory[W1_EEPROM_SIZE];

	u32	validcrc;

};



/**

 * Check the file size bounds and adjusts count as needed.

 * This may not be needed if the sysfs layer checks bounds.

 * This would not be needed if the file size didn't reset to 0 after a write.

 */

static inline size_t w1_f23_fix_count(loff_t off, size_t count, size_t size)

{
@@ -49,10 +59,45 @@ static inline size_t w1_f23_fix_count(loff_t off, size_t count, size_t size) 
	return count;

}



static ssize_t w1_f23_read_bin(struct kobject *kobj, char *buf, loff_t off, size_t count)

#ifdef CONFIG_W1_F23_CRC

static int w1_f23_refresh_block(struct w1_slave *sl, struct w1_f23_data *data,

				int block)

{

	u8	wrbuf[3];

	int	off = block * W1_PAGE_SIZE;



	if (data->validcrc & (1 << block))

		return 0;



	if (w1_reset_select_slave(sl)) {

		data->validcrc = 0;

		return -EIO;

	}



	wrbuf[0] = W1_F23_READ_EEPROM;

	wrbuf[1] = off & 0xff;

	wrbuf[2] = off >> 8;

	w1_write_block(sl->master, wrbuf, 3);

	w1_read_block(sl->master, &data->memory[off], W1_PAGE_SIZE);



	/* cache the block if the CRC is valid */

	if (crc16(CRC16_INIT, &data->memory[off], W1_PAGE_SIZE) == CRC16_VALID)

		data->validcrc |= (1 << block);



	return 0;

}

#endif	/* CONFIG_W1_F23_CRC */



static ssize_t w1_f23_read_bin(struct kobject *kobj, char *buf, loff_t off,

			       size_t count)

{

	struct w1_slave *sl = kobj_to_w1_slave(kobj);

#ifdef CONFIG_W1_F23_CRC

	struct w1_f23_data *data = sl->family_data;

	int i, min_page, max_page;

#else

	u8 wrbuf[3];

#endif



	if ((count = w1_f23_fix_count(off, count, W1_EEPROM_SIZE)) == 0)

		return 0;
@@ -63,6 +108,20 @@ static ssize_t w1_f23_read_bin(struct kobject *kobj, char *buf, loff_t off, size 
		goto out_dec;

	}



#ifdef CONFIG_W1_F23_CRC



	min_page = (off >> W1_PAGE_BITS);

	max_page = (off + count - 1) >> W1_PAGE_BITS;

	for (i = min_page; i <= max_page; i++) {

		if (w1_f23_refresh_block(sl, data, i)) {

			count = -EIO;

			goto out_up;

		}

	}

	memcpy(buf, &data->memory[off], count);



#else 	/* CONFIG_W1_F23_CRC */



	/* read directly from the EEPROM */

	if (w1_reset_select_slave(sl)) {

		count = -EIO;
@@ -75,6 +134,8 @@ static ssize_t w1_f23_read_bin(struct kobject *kobj, char *buf, loff_t off, size 
	w1_write_block(sl->master, wrbuf, 3);

	w1_read_block(sl->master, buf, count);



#endif	/* CONFIG_W1_F23_CRC */



out_up:

	up(&sl->master->mutex);

out_dec:
@@ -85,6 +146,8 @@ out_dec: 


/**

 * Writes to the scratchpad and reads it back for verification.

 * Then copies the scratchpad to EEPROM.

 * The data must be on one page.

 * The master must be locked.

 *

 * @param sl	The slave structure
@@ -148,6 +211,23 @@ static ssize_t w1_f23_write_bin(struct kobject *kobj, char *buf, loff_t off, 
	if ((count = w1_f23_fix_count(off, count, W1_EEPROM_SIZE)) == 0)

		return 0;



#ifdef CONFIG_W1_F23_CRC

	/* can only write full blocks in cached mode */

	if ((off & W1_PAGE_MASK) || (count & W1_PAGE_MASK)) {

		dev_err(&sl->dev, "invalid offset/count off=%d cnt=%d\n",

			(int)off, count);

		return -EINVAL;

	}



	/* make sure the block CRCs are valid */

	for (idx = 0; idx < count; idx += W1_PAGE_SIZE) {

		if (crc16(CRC16_INIT, &buf[idx], W1_PAGE_SIZE) != CRC16_VALID) {

			dev_err(&sl->dev, "bad CRC at offset %d\n", (int)off);

			return -EINVAL;

		}

	}

#endif	/* CONFIG_W1_F23_CRC */



	atomic_inc(&sl->refcnt);

	if (down_interruptible(&sl->master->mutex)) {

		count = 0;
@@ -190,11 +270,36 @@ static struct bin_attribute w1_f23_bin_attr = { 


static int w1_f23_add_slave(struct w1_slave *sl)

{

	return sysfs_create_bin_file(&sl->dev.kobj, &w1_f23_bin_attr);

	int err;

#ifdef CONFIG_W1_F23_CRC

	struct w1_f23_data *data;



	data = kmalloc(sizeof(struct w1_f23_data), GFP_KERNEL);

	if (!data)

		return -ENOMEM;

	memset(data, 0, sizeof(struct w1_f23_data));

	sl->family_data = data;



#endif	/* CONFIG_W1_F23_CRC */



	err = sysfs_create_bin_file(&sl->dev.kobj, &w1_f23_bin_attr);



#ifdef CONFIG_W1_F23_CRC

	if (err)

		kfree(data);

#endif	/* CONFIG_W1_F23_CRC */



	return err;

}



static void w1_f23_remove_slave(struct w1_slave *sl)

{

#ifdef CONFIG_W1_F23_CRC

	if (sl->family_data) {

		kfree(sl->family_data);

		sl->family_data = NULL;

	}

#endif	/* CONFIG_W1_F23_CRC */

	sysfs_remove_bin_file(&sl->dev.kobj, &w1_f23_bin_attr);

}