w1: DS2423 counter driver and documentation (17fecb55) · Commits · e / devices / android_kernel_fairphone_FP4

Documentation/w1/slaves/00-INDEX

+2 −0

Original line number	Diff line number	Diff line
		@@ -2,3 +2,5 @@
		- This file
		w1_therm
		- The Maxim/Dallas Semiconductor ds18*20 temperature sensor.
		w1_ds2423
		- The Maxim/Dallas Semiconductor ds2423 counter device.

Documentation/w1/slaves/w1_ds2423

0 → 100644

+47 −0

Original line number	Diff line number	Diff line
		Kernel driver w1_ds2423
		=======================

		Supported chips:
		* Maxim DS2423 based counter devices.

		supported family codes:
		W1_THERM_DS2423 0x1D

		Author: Mika Laitio <lamikr@pilppa.org>

		Description
		-----------

		Support is provided through the sysfs w1_slave file. Each opening and
		read sequence of w1_slave file initiates the read of counters and ram
		available in DS2423 pages 12 - 15.

		Result of each page is provided as an ASCII output where each counter
		value and associated ram buffer is outpputed to own line.

		Each lines will contain the values of 42 bytes read from the counter and
		memory page along the crc=YES or NO for indicating whether the read operation
		was successfull and CRC matched.
		If the operation was successfull, there is also in the end of each line
		a counter value expressed as an integer after c=

		Meaning of 42 bytes represented is following:
		- 1 byte from ram page
		- 4 bytes for the counter value
		- 4 zero bytes
		- 2 bytes for crc16 which was calculated from the data read since the previous crc bytes
		- 31 remaining bytes from the ram page
		- crc=YES/NO indicating whether read was ok and crc matched
		- c=<int> current counter value

		example from the successfull read:
		00 02 00 00 00 00 00 00 00 6d 38 00 ff ff 00 00 fe ff 00 00 ff ff 00 00 ff ff 00 00 ff ff 00 00 ff ff 00 00 ff ff 00 00 ff ff crc=YES c=2
		00 02 00 00 00 00 00 00 00 e0 1f 00 ff ff 00 00 ff ff 00 00 ff ff 00 00 ff ff 00 00 ff ff 00 00 ff ff 00 00 ff ff 00 00 ff ff crc=YES c=2
		00 29 c6 5d 18 00 00 00 00 04 37 00 ff ff 00 00 ff ff 00 00 ff ff 00 00 ff ff 00 00 ff ff 00 00 ff ff 00 00 ff ff 00 00 ff ff crc=YES c=408798761
		00 05 00 00 00 00 00 00 00 8d 39 ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff crc=YES c=5

		example from the read with crc errors:
		00 02 00 00 00 00 00 00 00 6d 38 00 ff ff 00 00 fe ff 00 00 ff ff 00 00 ff ff 00 00 ff ff 00 00 ff ff 00 00 ff ff 00 00 ff ff crc=YES c=2
		00 02 00 00 22 00 00 00 00 e0 1f 00 ff ff 00 00 ff ff 00 00 ff ff 00 00 ff ff 00 00 ff ff 00 00 ff ff 00 00 ff ff 00 00 ff ff crc=NO
		00 e1 61 5d 19 00 00 00 00 df 0b 00 ff ff 00 00 ff ff 00 00 ff ff 00 00 ff ff 00 00 ff ff 00 00 ff ff 00 00 ff ff 00 00 ff ff crc=NO
		00 05 00 00 20 00 00 00 00 8d 39 ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff crc=NO

drivers/w1/slaves/Kconfig

+11 −0

Original line number	Diff line number	Diff line
		@@ -16,6 +16,17 @@ config W1_SLAVE_SMEM
		Say Y here if you want to connect 1-wire
		simple 64bit memory rom(ds2401/ds2411/ds1990*) to your wire.

		config W1_SLAVE_DS2423
		tristate "Counter 1-wire device (DS2423)"
		select CRC16
		help
		If you enable this you can read the counter values available
		in the DS2423 chipset from the w1_slave file under the
		sys file system.

		Say Y here if you want to use a 1-wire
		counter family device (DS2423).

		config W1_SLAVE_DS2431
		tristate "1kb EEPROM family support (DS2431)"
		help

drivers/w1/slaves/Makefile

+1 −0

Original line number	Diff line number	Diff line
		@@ -4,6 +4,7 @@

		obj-$(CONFIG_W1_SLAVE_THERM) += w1_therm.o
		obj-$(CONFIG_W1_SLAVE_SMEM) += w1_smem.o
		obj-$(CONFIG_W1_SLAVE_DS2423) += w1_ds2423.o
		obj-$(CONFIG_W1_SLAVE_DS2431) += w1_ds2431.o
		obj-$(CONFIG_W1_SLAVE_DS2433) += w1_ds2433.o
		obj-$(CONFIG_W1_SLAVE_DS2760) += w1_ds2760.o

drivers/w1/slaves/w1_ds2423.c

0 → 100644

+166 −0

Original line number	Diff line number	Diff line
		/*
		* w1_ds2423.c
		*
		* Copyright (c) 2010 Mika Laitio <lamikr@pilppa.org>
		*
		* This driver will read and write the value of 4 counters to w1_slave file in
		* sys filesystem.
		* Inspired by the w1_therm and w1_ds2431 drivers.
		*
		* This program is free software; you can redistribute it and/or modify
		* it under the therms of the GNU General Public License as published by
		* the Free Software Foundation; either version 2 of the License, or
		* (at your option) any later version.
		*
		* This program is distributed in the hope that it will be useful,
		* but WITHOUT ANY WARRANTY; without even the implied warranty of
		* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
		* GNU General Public License for more details.
		*
		* You should have received a copy of the GNU General Public License
		* along with this program; if not, write to the Free Software
		* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
		*/

		#include <linux/kernel.h>
		#include <linux/module.h>
		#include <linux/moduleparam.h>
		#include <linux/device.h>
		#include <linux/types.h>
		#include <linux/delay.h>
		#include <linux/crc16.h>

		#include "../w1.h"
		#include "../w1_int.h"
		#include "../w1_family.h"

		#define CRC16_VALID 0xb001
		#define CRC16_INIT 0

		#define COUNTER_COUNT 4
		#define READ_BYTE_COUNT 42

		static ssize_t w1_counter_read(struct device *device,
		struct device_attribute attr, char buf);

		static struct device_attribute w1_counter_attr =
		__ATTR(w1_slave, S_IRUGO, w1_counter_read, NULL);

		static ssize_t w1_counter_read(struct device *device,
		struct device_attribute attr, char out_buf)
		{
		struct w1_slave *sl = dev_to_w1_slave(device);
		struct w1_master *dev = sl->master;
		u8 rbuf[COUNTER_COUNT * READ_BYTE_COUNT];
		u8 wrbuf[3];
		int rom_addr;
		int read_byte_count;
		int result;
		ssize_t c;
		int ii;
		int p;
		int crc;

		c = PAGE_SIZE;
		rom_addr = (12 << 5) + 31;
		wrbuf[0] = 0xA5;
		wrbuf[1] = rom_addr & 0xFF;
		wrbuf[2] = rom_addr >> 8;
		mutex_lock(&dev->mutex);
		if (!w1_reset_select_slave(sl)) {
		w1_write_block(dev, wrbuf, 3);
		read_byte_count = 0;
		for (p = 0; p < 4; p++) {
		/*
		* 1 byte for first bytes in ram page read
		* 4 bytes for counter
		* 4 bytes for zero bits
		* 2 bytes for crc
		* 31 remaining bytes from the ram page
		*/
		read_byte_count += w1_read_block(dev,
		rbuf + (p * READ_BYTE_COUNT), READ_BYTE_COUNT);
		for (ii = 0; ii < READ_BYTE_COUNT; ++ii)
		c -= snprintf(out_buf + PAGE_SIZE - c,
		c, "%02x ",
		rbuf[(p * READ_BYTE_COUNT) + ii]);
		if (read_byte_count != (p + 1) * READ_BYTE_COUNT) {
		dev_warn(device,
		"w1_counter_read() returned %u bytes "
		"instead of %d bytes wanted.\n",
		read_byte_count,
		READ_BYTE_COUNT);
		c -= snprintf(out_buf + PAGE_SIZE - c,
		c, "crc=NO\n");
		} else {
		if (p == 0) {
		crc = crc16(CRC16_INIT, wrbuf, 3);
		crc = crc16(crc, rbuf, 11);
		} else {
		/*
		* DS2423 calculates crc from all bytes
		* read after the previous crc bytes.
		*/
		crc = crc16(CRC16_INIT,
		(rbuf + 11) +
		((p - 1) * READ_BYTE_COUNT),
		READ_BYTE_COUNT);
		}
		if (crc == CRC16_VALID) {
		result = 0;
		for (ii = 4; ii > 0; ii--) {
		result <<= 8;
		result \|= rbuf[(p *
		READ_BYTE_COUNT) + ii];
		}
		c -= snprintf(out_buf + PAGE_SIZE - c,
		c, "crc=YES c=%d\n", result);
		} else {
		c -= snprintf(out_buf + PAGE_SIZE - c,
		c, "crc=NO\n");
		}
		}
		}
		} else {
		c -= snprintf(out_buf + PAGE_SIZE - c, c, "Connection error");
		}
		mutex_unlock(&dev->mutex);
		return PAGE_SIZE - c;
		}

		static int w1_f1d_add_slave(struct w1_slave *sl)
		{
		return device_create_file(&sl->dev, &w1_counter_attr);
		}

		static void w1_f1d_remove_slave(struct w1_slave *sl)
		{
		device_remove_file(&sl->dev, &w1_counter_attr);
		}

		static struct w1_family_ops w1_f1d_fops = {
		.add_slave = w1_f1d_add_slave,
		.remove_slave = w1_f1d_remove_slave,
		};

		static struct w1_family w1_family_1d = {
		.fid = W1_COUNTER_DS2423,
		.fops = &w1_f1d_fops,
		};

		static int __init w1_f1d_init(void)
		{
		return w1_register_family(&w1_family_1d);
		}

		static void __exit w1_f1d_exit(void)
		{
		w1_unregister_family(&w1_family_1d);
		}

		module_init(w1_f1d_init);
		module_exit(w1_f1d_exit);

		MODULE_LICENSE("GPL");
		MODULE_AUTHOR("Mika Laitio <lamikr@pilppa.org>");
		MODULE_DESCRIPTION("w1 family 1d driver for DS2423, 4 counters and 4kb ram");