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[PATCH] w1_ds2433: Added crc16 protection and read caching.

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

Signed-off-by: Ben Gardner <bgardner@wabtec.com>
Signed-off-by: Evgeniy Polyakov <johnpol@2ka.mipt.ru>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
This commit is contained in:
Evgeniy Polyakov 2005-08-17 15:24:37 +04:00 committed by Greg Kroah-Hartman
parent a45f105ad4
commit 0a25e4d564
3 changed files with 125 additions and 7 deletions
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9
drivers/w1/Kconfig
View File

@ -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

6
drivers/w1/Makefile
View File

@ -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-$(CONFIG_W1) += wire.o
wire-objs := w1.o w1_int.o w1_family.o w1_netlink.o w1_io.o
@ -13,7 +17,7 @@ obj-$(CONFIG_W1_MATROX) += matrox_w1.o
obj-$(CONFIG_W1_THERM) += w1_therm.o
obj-$(CONFIG_W1_SMEM) += w1_smem.o
obj-$(CONFIG_W1_DS9490) += ds9490r.o
obj-$(CONFIG_W1_DS9490) += ds9490r.o
ds9490r-objs := dscore.o
obj-$(CONFIG_W1_DS9490_BRIDGE) += ds_w1_bridge.o

117
drivers/w1/w1_ds2433.c
View File

@ -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);
}