w1: Add support for DS28EA00 sequence to w1-therm

This patch provides support for the DS28EA00 digital thermometer.

The DS28EA00 provides an additional two pins for implementing a sequence
detection algorithm.  This feature allows you to determine the physical
location of the chip in the 1-wire bus without needing pre-existing
knowledge of the bus ordering.  Support is provided through the sysfs
w1_seq file.  The file will contain a single line with an integer value
representing the device index in the bus starting at 0.

Signed-off-by: Matt Campbell <mattrcampbell@gmail.com>
Acked-by: Evgeniy Polyakov <zbr@ioremap.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/Documentation/ABI/stable/sysfs-driver-w1_ds28ea00 b/Documentation/ABI/stable/sysfs-driver-w1_ds28ea00
new file mode 100644 (file)
index 0000000..e928def
--- /dev/null
+++ b/Documentation/ABI/stable/sysfs-driver-w1_ds28ea00
@@ -0,0 +1,6 @@
+What:          /sys/bus/w1/devices/.../w1_seq
+Date:          Apr 2015
+Contact:       Matt Campbell <mattrcampbell@gmail.com>
+Description:   Support for the DS28EA00 chain sequence function
+               see Documentation/w1/slaves/w1_therm for detailed information
+Users:         any user space application which wants to communicate with DS28EA00

diff --git a/Documentation/w1/slaves/w1_therm b/Documentation/w1/slaves/w1_therm
index cc62a95e4776f2233ad0df424a02da4fd465d129..13411fe52f7ff49b2ab5db2e9fca18ffaf98aefc 100644 (file)
--- a/Documentation/w1/slaves/w1_therm
+++ b/Documentation/w1/slaves/w1_therm
@@ -11,12 +11,14 @@ Author: Evgeniy Polyakov <johnpol@2ka.mipt.ru>
 Description
 -----------
 
-w1_therm provides basic temperature conversion for ds18*20 devices.
+w1_therm provides basic temperature conversion for ds18*20 devices, and the
+ds28ea00 device.
 supported family codes:
 W1_THERM_DS18S20       0x10
 W1_THERM_DS1822                0x22
 W1_THERM_DS18B20       0x28
 W1_THERM_DS1825                0x3B
+W1_THERM_DS28EA00      0x42
 
 Support is provided through the sysfs w1_slave file.  Each open and
 read sequence will initiate a temperature conversion then provide two
@@ -48,3 +50,10 @@ resistor).  The DS18b20 temperature sensor specification lists a
 maximum current draw of 1.5mA and that a 5k pullup resistor is not
 sufficient.  The strong pullup is designed to provide the additional
 current required.
+
+The DS28EA00 provides an additional two pins for implementing a sequence
+detection algorithm.  This feature allows you to determine the physical
+location of the chip in the 1-wire bus without needing pre-existing
+knowledge of the bus ordering.  Support is provided through the sysfs
+w1_seq file.  The file will contain a single line with an integer value
+representing the device index in the bus starting at 0.

diff --git a/drivers/w1/slaves/w1_therm.c b/drivers/w1/slaves/w1_therm.c
index 55eb86c9e214109256312990e7d532090b7d3017..d21e6864b06fc18c4fc7b6c93a876ac2fe64e21d 100644 (file)
--- a/drivers/w1/slaves/w1_therm.c
+++ b/drivers/w1/slaves/w1_therm.c
@@ -92,13 +92,24 @@ static void w1_therm_remove_slave(struct w1_slave *sl)
 static ssize_t w1_slave_show(struct device *device,
        struct device_attribute *attr, char *buf);
 
+static ssize_t w1_seq_show(struct device *device,
+       struct device_attribute *attr, char *buf);
+
 static DEVICE_ATTR_RO(w1_slave);
+static DEVICE_ATTR_RO(w1_seq);
 
 static struct attribute *w1_therm_attrs[] = {
        &dev_attr_w1_slave.attr,
        NULL,
 };
+
+static struct attribute *w1_ds28ea00_attrs[] = {
+       &dev_attr_w1_slave.attr,
+       &dev_attr_w1_seq.attr,
+       NULL,
+};
 ATTRIBUTE_GROUPS(w1_therm);
+ATTRIBUTE_GROUPS(w1_ds28ea00);
 
 static struct w1_family_ops w1_therm_fops = {
        .add_slave      = w1_therm_add_slave,
@@ -106,6 +117,12 @@ static struct w1_family_ops w1_therm_fops = {
        .groups         = w1_therm_groups,
 };
 
+static struct w1_family_ops w1_ds28ea00_fops = {
+       .add_slave      = w1_therm_add_slave,
+       .remove_slave   = w1_therm_remove_slave,
+       .groups         = w1_ds28ea00_groups,
+};
+
 static struct w1_family w1_therm_family_DS18S20 = {
        .fid = W1_THERM_DS18S20,
        .fops = &w1_therm_fops,
@@ -123,7 +140,7 @@ static struct w1_family w1_therm_family_DS1822 = {
 
 static struct w1_family w1_therm_family_DS28EA00 = {
        .fid = W1_THERM_DS28EA00,
-       .fops = &w1_therm_fops,
+       .fops = &w1_ds28ea00_fops,
 };
 
 static struct w1_family w1_therm_family_DS1825 = {
@@ -316,6 +333,89 @@ post_unlock:
        return ret;
 }
 
+#define W1_42_CHAIN    0x99
+#define W1_42_CHAIN_OFF        0x3C
+#define W1_42_CHAIN_OFF_INV    0xC3
+#define W1_42_CHAIN_ON 0x5A
+#define W1_42_CHAIN_ON_INV     0xA5
+#define W1_42_CHAIN_DONE 0x96
+#define W1_42_CHAIN_DONE_INV 0x69
+#define W1_42_COND_READ        0x0F
+#define W1_42_SUCCESS_CONFIRM_BYTE 0xAA
+#define W1_42_FINISHED_BYTE 0xFF
+static ssize_t w1_seq_show(struct device *device,
+       struct device_attribute *attr, char *buf)
+{
+       struct w1_slave *sl = dev_to_w1_slave(device);
+       ssize_t c = PAGE_SIZE;
+       int rv;
+       int i;
+       u8 ack;
+       u64 rn;
+       struct w1_reg_num *reg_num;
+       int seq = 0;
+
+       mutex_lock(&sl->master->mutex);
+       /* Place all devices in CHAIN state */
+       if (w1_reset_bus(sl->master))
+               goto error;
+       w1_write_8(sl->master, W1_SKIP_ROM);
+       w1_write_8(sl->master, W1_42_CHAIN);
+       w1_write_8(sl->master, W1_42_CHAIN_ON);
+       w1_write_8(sl->master, W1_42_CHAIN_ON_INV);
+       msleep(sl->master->pullup_duration);
+
+       /* check for acknowledgment */
+       ack = w1_read_8(sl->master);
+       if (ack != W1_42_SUCCESS_CONFIRM_BYTE)
+               goto error;
+
+       /* In case the bus fails to send 0xFF, limit*/
+       for (i = 0; i <= 64; i++) {
+               if (w1_reset_bus(sl->master))
+                       goto error;
+
+               w1_write_8(sl->master, W1_42_COND_READ);
+               rv = w1_read_block(sl->master, (u8 *)&rn, 8);
+               reg_num = (struct w1_reg_num *) &rn;
+               if ((char)reg_num->family == W1_42_FINISHED_BYTE)
+                       break;
+               if (sl->reg_num.id == reg_num->id)
+                       seq = i;
+
+               w1_write_8(sl->master, W1_42_CHAIN);
+               w1_write_8(sl->master, W1_42_CHAIN_DONE);
+               w1_write_8(sl->master, W1_42_CHAIN_DONE_INV);
+               w1_read_block(sl->master, &ack, sizeof(ack));
+
+               /* check for acknowledgment */
+               ack = w1_read_8(sl->master);
+               if (ack != W1_42_SUCCESS_CONFIRM_BYTE)
+                       goto error;
+
+       }
+
+       /* Exit from CHAIN state */
+       if (w1_reset_bus(sl->master))
+               goto error;
+       w1_write_8(sl->master, W1_SKIP_ROM);
+       w1_write_8(sl->master, W1_42_CHAIN);
+       w1_write_8(sl->master, W1_42_CHAIN_OFF);
+       w1_write_8(sl->master, W1_42_CHAIN_OFF_INV);
+
+       /* check for acknowledgment */
+       ack = w1_read_8(sl->master);
+       if (ack != W1_42_SUCCESS_CONFIRM_BYTE)
+               goto error;
+       mutex_unlock(&sl->master->mutex);
+
+       c -= snprintf(buf + PAGE_SIZE - c, c, "%d\n", seq);
+       return PAGE_SIZE - c;
+error:
+       mutex_unlock(&sl->master->bus_mutex);
+       return -EIO;
+}
+
 static int __init w1_therm_init(void)
 {
        int err, i;