--- /dev/null
+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
--- /dev/null
+/*
+ * 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");
projects / GitHub / mt8127 / android_kernel_alcatel_ttab.git / commitdiff