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authorScott Alfter <scott@alfter.us>2014-06-18 00:42:05 +0400
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2014-06-20 04:45:14 +0400
commit94859308a21b2bbf3d7c48789513c0c4a9ea7de1 (patch)
treea929e9e6f3dd3d81deeee65c6eb221c8488435a1 /drivers/w1/slaves/w1_ds2406.c
parent7242d42ace30825553eabd424b41b03136d37faa (diff)
downloadlinux-94859308a21b2bbf3d7c48789513c0c4a9ea7de1.tar.xz
w1: new w1_ds2406 driver
Some preliminary work at making use of this driver led me to implement CRC-16 checks on read and write to deal with the occasional glitchiness of the 1-Wire bus. The revised driver (attached) returns an I/O error if the CRC check fails. When reading the chip's state, either you get a valid indication or you get an I/O error. When changing its state, either the change is successful or an I/O error is returned. Signed-off-by: Scott Alfter <scott@alfter.us> Acked-by: Evgeniy Polyakov <zbr@ioremap.net> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'drivers/w1/slaves/w1_ds2406.c')
-rw-r--r--drivers/w1/slaves/w1_ds2406.c168
1 files changed, 168 insertions, 0 deletions
diff --git a/drivers/w1/slaves/w1_ds2406.c b/drivers/w1/slaves/w1_ds2406.c
new file mode 100644
index 000000000000..d488961a8c90
--- /dev/null
+++ b/drivers/w1/slaves/w1_ds2406.c
@@ -0,0 +1,168 @@
+/*
+ * w1_ds2406.c - w1 family 12 (DS2406) driver
+ * based on w1_ds2413.c by Mariusz Bialonczyk <manio@skyboo.net>
+ *
+ * Copyright (c) 2014 Scott Alfter <scott@alfter.us>
+ *
+ * This source code is licensed under the GNU General Public License,
+ * Version 2. See the file COPYING for more details.
+ */
+
+#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/slab.h>
+#include <linux/crc16.h>
+
+#include "../w1.h"
+#include "../w1_int.h"
+#include "../w1_family.h"
+
+MODULE_LICENSE("GPL");
+MODULE_AUTHOR("Scott Alfter <scott@alfter.us>");
+MODULE_DESCRIPTION("w1 family 12 driver for DS2406 2 Pin IO");
+
+#define W1_F12_FUNC_READ_STATUS 0xAA
+#define W1_F12_FUNC_WRITE_STATUS 0x55
+
+static ssize_t w1_f12_read_state(
+ struct file *filp, struct kobject *kobj,
+ struct bin_attribute *bin_attr,
+ char *buf, loff_t off, size_t count)
+{
+ u8 w1_buf[6]={W1_F12_FUNC_READ_STATUS, 7, 0, 0, 0, 0};
+ struct w1_slave *sl = kobj_to_w1_slave(kobj);
+ u16 crc=0;
+ int i;
+ ssize_t rtnval=1;
+
+ if (off != 0)
+ return 0;
+ if (!buf)
+ return -EINVAL;
+
+ mutex_lock(&sl->master->bus_mutex);
+
+ if (w1_reset_select_slave(sl)) {
+ mutex_unlock(&sl->master->bus_mutex);
+ return -EIO;
+ }
+
+ w1_write_block(sl->master, w1_buf, 3);
+ w1_read_block(sl->master, w1_buf+3, 3);
+ for (i=0; i<6; i++)
+ crc=crc16_byte(crc, w1_buf[i]);
+ if (crc==0xb001) /* good read? */
+ *buf=((w1_buf[3]>>5)&3)|0x30;
+ else
+ rtnval=-EIO;
+
+ mutex_unlock(&sl->master->bus_mutex);
+
+ return rtnval;
+}
+
+static ssize_t w1_f12_write_output(
+ struct file *filp, struct kobject *kobj,
+ struct bin_attribute *bin_attr,
+ char *buf, loff_t off, size_t count)
+{
+ struct w1_slave *sl = kobj_to_w1_slave(kobj);
+ u8 w1_buf[6]={W1_F12_FUNC_WRITE_STATUS, 7, 0, 0, 0, 0};
+ u16 crc=0;
+ int i;
+ ssize_t rtnval=1;
+
+ if (count != 1 || off != 0)
+ return -EFAULT;
+
+ mutex_lock(&sl->master->bus_mutex);
+
+ if (w1_reset_select_slave(sl)) {
+ mutex_unlock(&sl->master->bus_mutex);
+ return -EIO;
+ }
+
+ w1_buf[3] = (((*buf)&3)<<5)|0x1F;
+ w1_write_block(sl->master, w1_buf, 4);
+ w1_read_block(sl->master, w1_buf+4, 2);
+ for (i=0; i<6; i++)
+ crc=crc16_byte(crc, w1_buf[i]);
+ if (crc==0xb001) /* good read? */
+ w1_write_8(sl->master, 0xFF);
+ else
+ rtnval=-EIO;
+
+ mutex_unlock(&sl->master->bus_mutex);
+ return rtnval;
+}
+
+#define NB_SYSFS_BIN_FILES 2
+static struct bin_attribute w1_f12_sysfs_bin_files[NB_SYSFS_BIN_FILES] = {
+ {
+ .attr = {
+ .name = "state",
+ .mode = S_IRUGO,
+ },
+ .size = 1,
+ .read = w1_f12_read_state,
+ },
+ {
+ .attr = {
+ .name = "output",
+ .mode = S_IRUGO | S_IWUSR | S_IWGRP,
+ },
+ .size = 1,
+ .write = w1_f12_write_output,
+ }
+};
+
+static int w1_f12_add_slave(struct w1_slave *sl)
+{
+ int err = 0;
+ int i;
+
+ for (i = 0; i < NB_SYSFS_BIN_FILES && !err; ++i)
+ err = sysfs_create_bin_file(
+ &sl->dev.kobj,
+ &(w1_f12_sysfs_bin_files[i]));
+ if (err)
+ while (--i >= 0)
+ sysfs_remove_bin_file(&sl->dev.kobj,
+ &(w1_f12_sysfs_bin_files[i]));
+ return err;
+}
+
+static void w1_f12_remove_slave(struct w1_slave *sl)
+{
+ int i;
+ for (i = NB_SYSFS_BIN_FILES - 1; i >= 0; --i)
+ sysfs_remove_bin_file(&sl->dev.kobj,
+ &(w1_f12_sysfs_bin_files[i]));
+}
+
+static struct w1_family_ops w1_f12_fops = {
+ .add_slave = w1_f12_add_slave,
+ .remove_slave = w1_f12_remove_slave,
+};
+
+static struct w1_family w1_family_12 = {
+ .fid = W1_FAMILY_DS2406,
+ .fops = &w1_f12_fops,
+};
+
+static int __init w1_f12_init(void)
+{
+ return w1_register_family(&w1_family_12);
+}
+
+static void __exit w1_f12_exit(void)
+{
+ w1_unregister_family(&w1_family_12);
+}
+
+module_init(w1_f12_init);
+module_exit(w1_f12_exit);