From: David Fries <david@fries.net>
To: Andrew Morton <akpm@linux-foundation.org>
Cc: linux-kernel@vger.kernel.org, Evgeniy Polyakov <johnpol@2ka.mipt.ru>
Subject: [PATCH 6/30] W1: feature, w1_therm.c use strong pullup and documentation
Date: Mon, 28 Jul 2008 21:15:29 -0500 [thread overview]
Message-ID: <20080729021529.GF24452@spacedout.fries.net> (raw)
In-Reply-To: <20080729020433.GA24424@spacedout.fries.net>
[-- Attachment #1: Type: text/plain, Size: 4339 bytes --]
Added strong pullup to thermal sensor driver and general documentation
on the sensor.
Signed-off-by: David Fries <david@fries.net>
Signed-off-by: Evgeniy Polyakov <johnpol@2ka.mipt.ru>
---
Documentation/w1/00-INDEX | 2 +
Documentation/w1/slaves/00-INDEX | 4 +++
Documentation/w1/slaves/w1_therm | 41 ++++++++++++++++++++++++++++++++++++++
drivers/w1/slaves/w1_therm.c | 15 ++++++++++++-
4 files changed, 60 insertions(+), 2 deletions(-)
diff --git a/Documentation/w1/00-INDEX b/Documentation/w1/00-INDEX
index 5270cf4..cb49802 100644
--- a/Documentation/w1/00-INDEX
+++ b/Documentation/w1/00-INDEX
@@ -1,5 +1,7 @@
00-INDEX
- This file
+slaves/
+ - Drivers that provide support for specific family codes.
masters/
- Individual chips providing 1-wire busses.
w1.generic
diff --git a/Documentation/w1/slaves/00-INDEX b/Documentation/w1/slaves/00-INDEX
new file mode 100644
index 0000000..f8101d6
--- /dev/null
+++ b/Documentation/w1/slaves/00-INDEX
@@ -0,0 +1,4 @@
+00-INDEX
+ - This file
+w1_therm
+ - The Maxim/Dallas Semiconductor ds18*20 temperature sensor.
diff --git a/Documentation/w1/slaves/w1_therm b/Documentation/w1/slaves/w1_therm
new file mode 100644
index 0000000..0403aaa
--- /dev/null
+++ b/Documentation/w1/slaves/w1_therm
@@ -0,0 +1,41 @@
+Kernel driver w1_therm
+====================
+
+Supported chips:
+ * Maxim ds18*20 based temperature sensors.
+
+Author: Evgeniy Polyakov <johnpol@2ka.mipt.ru>
+
+
+Description
+-----------
+
+w1_therm provides basic temperature conversion for ds18*20 devices.
+supported family codes:
+W1_THERM_DS18S20 0x10
+W1_THERM_DS1822 0x22
+W1_THERM_DS18B20 0x28
+
+Support is provided through the sysfs w1_slave file. Each open and
+read sequence will initiate a temperature conversion then provide two
+lines of ASCII output. The first line contains the nine hex bytes
+read along with a calculated crc value and YES or NO if it matched.
+If the crc matched the returned values are retained. The second line
+displays the retained values along with a temperature in millidegrees
+Centigrade after t=.
+
+Parasite powered devices are limited to one slave performing a
+temperature conversion at a time. If none of the devices are parasite
+powered it would be possible to convert all the devices at the same
+time and then go back to read individual sensors. That isn't
+currently supported. The driver also doesn't support reduced
+precision (which would also reduce the conversion time).
+
+The module parameter strong_pullup can be set to 0 to disable the
+strong pullup or 1 to enable. If enabled the 5V strong pullup will be
+enabled when the conversion is taking place provided the master driver
+must support the strong pullup (or it falls back to a pullup
+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.
diff --git a/drivers/w1/slaves/w1_therm.c b/drivers/w1/slaves/w1_therm.c
index fb28aca..e87f464 100644
--- a/drivers/w1/slaves/w1_therm.c
+++ b/drivers/w1/slaves/w1_therm.c
@@ -37,6 +37,14 @@ MODULE_LICENSE("GPL");
MODULE_AUTHOR("Evgeniy Polyakov <johnpol@2ka.mipt.ru>");
MODULE_DESCRIPTION("Driver for 1-wire Dallas network protocol, temperature family.");
+/* Allow the strong pullup to be disabled, but default to enabled.
+ * If it was disabled a parasite powered device might not get the require
+ * current to do a temperature conversion. If it is enabled parasite powered
+ * devices have a better chance of getting the current required.
+ */
+static int w1_strong_pullup = 1;
+module_param_named(strong_pullup, w1_strong_pullup, int, 0);
+
static u8 bad_roms[][9] = {
{0xaa, 0x00, 0x4b, 0x46, 0xff, 0xff, 0x0c, 0x10, 0x87},
{}
@@ -192,9 +200,12 @@ static ssize_t w1_therm_read_bin(struct kobject *kobj,
int count = 0;
unsigned int tm = 750;
+ /* 750ms strong pullup (or delay) after the convert */
+ if (w1_strong_pullup)
+ w1_next_pullup(dev, tm);
w1_write_8(dev, W1_CONVERT_TEMP);
-
- msleep(tm);
+ if (!w1_strong_pullup)
+ msleep(tm);
if (!w1_reset_select_slave(sl)) {
--
1.4.4.4
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next prev parent reply other threads:[~2008-07-29 2:16 UTC|newest]
Thread overview: 66+ messages / expand[flat|nested] mbox.gz Atom feed top
2008-07-29 2:04 [PATCH 0/30] W1: w1 core fixes, ds2490 updates, strong pullup David Fries
2008-07-29 2:10 ` [PATCH 1/30] W1: fix deadlocks and remove w1_control_thread David Fries
2008-07-29 2:12 ` [PATCH 2/30] W1: abort search early on on exit David Fries
2008-07-29 2:13 ` [PATCH 3/30] W1: don't delay search start David Fries
2008-07-29 2:14 ` [PATCH 4/30] W1: w1_process, block or sleep David Fries
2008-07-29 2:14 ` [PATCH 5/30] W1: feature, enable hardware strong pullup David Fries
2008-07-29 23:21 ` Andrew Morton
2008-07-29 2:15 ` David Fries [this message]
2008-07-29 2:17 ` [PATCH 7/30] W1: be able to manually add and remove slaves David Fries
2008-07-29 2:18 ` [PATCH 8/30] W1: recode w1_slave_found logic David Fries
2008-07-29 2:19 ` [PATCH 9/30] W1: new module parameter search_count David Fries
2008-07-29 2:20 ` [PATCH 10/30] W1: Document add, remove, search_count, and pullup David Fries
2008-07-29 2:21 ` [PATCH 11/30] W1: w1_slave_read_id read bug, use device_attribute David Fries
2008-07-29 2:21 ` [PATCH 12/30] W1: w1_therm fix user buffer overflow and cat David Fries
2008-07-29 2:21 ` [PATCH 13/30] W1: w1_family, remove unused variable need_exit David Fries
2008-07-29 2:22 ` [PATCH 14/30] W1: w1_therm consistent mutex access code cleanup David Fries
2008-07-29 2:23 ` [PATCH 15/30] W1: w1_int.c use first available master number David Fries
2008-07-29 2:23 ` [PATCH 16/30] W1: w1.c s/printk/dev_dbg/ David Fries
2008-07-29 2:24 ` [PATCH 17/30] W1: w1_io.c reset comments and msleep David Fries
2008-07-29 2:24 ` [PATCH 18/30] W1: ds1wm.c msleep for reset David Fries
2008-07-29 2:25 ` [PATCH 19/30] W1: ds2490.c correct print message David Fries
2008-07-29 2:25 ` [PATCH 20/30] W1: ds2490.c add support for strong pullup David Fries
2008-07-29 2:25 ` [PATCH 21/30] W1: ds2490.c ds_write_bit, grouping error, disable readback David Fries
2008-07-29 2:25 ` [PATCH 22/30] W1: ds2490.c disable bit read and write David Fries
2008-07-29 2:26 ` [PATCH 23/30] W1: ds2490.c simplify and fix ds_touch_bit David Fries
2008-07-29 2:26 ` [PATCH 24/30] W1: ds2490.c ds_dump_status rework David Fries
2008-07-29 2:26 ` [PATCH 25/30] W1: ds2490.c ds_reset remove ds_wait_status David Fries
2008-07-29 2:27 ` [PATCH 26/30] W1: ds2490.c reset ds2490 in init David Fries
2008-07-29 2:28 ` [PATCH 27/30] W1: ds2490.c magic number work David Fries
2008-07-29 2:28 ` [PATCH 28/30] W1: ds2490.c ds_write_block remove extra ds_wait_status David Fries
2008-07-29 2:29 ` [PATCH 29/30] W1: Documentation/w1/masters/ds2490 update David Fries
2008-07-29 2:30 ` [PATCH 30/30] W1: ds2490.c optimize ds_set_pullup David Fries
2008-07-29 23:13 ` [PATCH 0/30] W1: w1 core fixes, ds2490 updates, strong pullup Andrew Morton
2008-07-31 2:37 ` David Fries
2008-07-31 3:03 ` Andrew Morton
2008-07-31 2:47 ` [PATCH 1/30] W1: fix deadlocks and remove w1_control_thread David Fries
2008-07-31 2:48 ` [PATCH 2/30] W1: abort search early on on exit David Fries
2008-07-31 2:48 ` [PATCH 3/30] W1: don't delay search start David Fries
2008-07-31 2:48 ` [PATCH 4/30] W1: w1_process, block or sleep David Fries
2008-07-31 2:48 ` [PATCH 5/30] W1: feature, enable hardware strong pullup David Fries
2008-07-31 2:48 ` [PATCH 6/30] W1: feature, w1_therm.c use strong pullup and documentation David Fries
2008-07-31 2:48 ` [PATCH 7/30] W1: be able to manually add and remove slaves David Fries
2008-07-31 2:48 ` [PATCH 8/30] W1: recode w1_slave_found logic David Fries
2008-07-31 2:48 ` [PATCH 9/30] W1: new module parameter search_count David Fries
2008-07-31 2:49 ` [PATCH 10/30] W1: Document add, remove, search_count, and pullup David Fries
2008-07-31 2:49 ` [PATCH 11/30] W1: w1_slave_read_id read bug, use device_attribute David Fries
2008-07-31 2:49 ` [PATCH 12/30] W1: w1_therm fix user buffer overflow and cat David Fries
2008-07-31 2:49 ` [PATCH 13/30] W1: w1_family, remove unused variable need_exit David Fries
2008-07-31 2:49 ` [PATCH 14/30] W1: w1_therm consistent mutex access code cleanup David Fries
2008-07-31 2:49 ` [PATCH 15/30] W1: w1_int.c use first available master number David Fries
2008-07-31 2:49 ` [PATCH 16/30] W1: w1.c s/printk/dev_dbg/ David Fries
2008-07-31 2:49 ` [PATCH 17/30] W1: w1_io.c reset comments and msleep David Fries
2008-07-31 2:49 ` [PATCH 18/30] W1: ds1wm.c msleep for reset David Fries
2008-07-31 2:49 ` [PATCH 19/30] W1: ds2490.c correct print message David Fries
2008-07-31 2:49 ` [PATCH 20/30] W1: ds2490.c add support for strong pullup David Fries
2008-07-31 2:50 ` [PATCH 21/30] W1: ds2490.c ds_write_bit, grouping error, disable readback David Fries
2008-07-31 2:50 ` [PATCH 22/30] W1: ds2490.c disable bit read and write David Fries
2008-07-31 2:50 ` [PATCH 23/30] W1: ds2490.c simplify and fix ds_touch_bit David Fries
2008-07-31 2:50 ` [PATCH 24/30] W1: ds2490.c ds_dump_status rework David Fries
2008-07-31 2:50 ` [PATCH 25/30] W1: ds2490.c ds_reset remove ds_wait_status David Fries
2008-07-31 2:50 ` [PATCH 26/30] W1: ds2490.c reset ds2490 in init David Fries
2008-07-31 2:50 ` [PATCH 27/30] W1: ds2490.c magic number work David Fries
2008-07-31 2:50 ` [PATCH 28/30] W1: ds2490.c ds_write_block remove extra ds_wait_status David Fries
2008-07-31 2:50 ` [PATCH 29/30] W1: Documentation/w1/masters/ds2490 update David Fries
2008-07-31 2:50 ` [PATCH 30/30] W1: ds2490.c optimize ds_set_pullup David Fries
-- strict thread matches above, loose matches on Subject: below --
2008-07-11 13:51 w1 updates Evgeniy Polyakov
2008-07-11 13:51 ` [PATCH 6/30] W1: feature, w1_therm.c use strong pullup and documentation Evgeniy Polyakov
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