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EvgeniK45

w1-therm driver modifications

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Good day!

 

I have made modifications to the kernel driver for the temperature sensor Dallas ds18b20 on w1 bus.

Slightly corrected timings, have achieved stable operation of sensors with parasitic power, and also added the option of changing the resolution.

Now you can easily set 9,10,11 or 12bit resolution, by a simple command "echo 9..12 > /sys/bus/w1/devices/28-xxxxxxx/w1-resolution".

Accordingly, when you lower the resolution significantly decreased the response time of the sensor from 1100ms (whith 12bit) down to 125ms (with 9bit).

 

My question is can I post here the modified source code of the driver, or it will violate any rights?

 

w1 folder, after modifications...

 

driver -> ../../../bus/w1/drivers/w1_slave_driver
id
name
power
subsystem -> ../../../bus/w1
uevent
w1_resolution
w1_slave
 

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Best way is to provide a patch to current driver or as a git pull request which is even more "Armbian developers friendly" :) This way, modifications will be available for all users in matter of days since we need to urgently release one bug release this week.

 

Regarding rights - I think adding your name to the patch, where changes to original code is viewed clearly, is the right / proper way. Perhaps add yourself also to the head with "Code modified by ...". Since I am not an opensource law specialist, don't take this tip as 100% proper way.

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Sorry, I didn't know how to provide a patch to current driver or as a git pull request.

I will try to sort out this issue...

 

> Since I am not an opensource law specialist, don't take this tip as 100% proper way.

I'm not an expert too, so decided to ask :)

 

I can make the patch file and do the driver files, which can be simply replaced in the system to verify.

But I understand that this forum does not allow attachments to messages or I am not right?

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Sorry, I didn't know how to provide a patch to current driver or as a git pull request.

I will try to sort out this issue...

 

Maybe you can try to provide the stuff somewhere else and post a link here? I just want to ensure, we're able to integrate your improvements even if you still lack the time to get familiar with github/patches :)

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I want to apologize, I thought that nobody interested in my modification, because the topic is stalled.  :(

If I make a patch file be enough?

--- w1/w1.h     2016-07-02 20:09:37.000000000 +0500
+++ w1.mod/w1.h 2016-06-12 19:36:58.000000000 +0500
@@ -52,6 +52,7 @@
 #define W1_CONVERT_TEMP                0x44
 #define W1_SKIP_ROM            0xCC
 #define W1_READ_SCRATCHPAD     0xBE
+#define W1_WRITE_SCRATCHPAD    0x4E
 #define W1_READ_ROM            0x33
 #define W1_READ_PSUPPLY                0xB4
 #define W1_MATCH_ROM           0x55
--- w1/w1_io.c  2016-07-02 20:09:37.000000000 +0500
+++ w1.mod/w1_io.c      2016-06-12 19:43:12.000000000 +0500
@@ -73,18 +73,18 @@
        }
 }

-/**
+/*
  * Generates a write-0 or write-1 cycle.
  * Only call if dev->bus_master->touch_bit is NULL
  */
 static void w1_write_bit(struct w1_master *dev, int bit)
 {
-       if (bit) {
+       if (bit) { // write 1
                dev->bus_master->write_bit(dev->bus_master->data, 0);
-               w1_delay(6);
+               w1_delay(5);
                dev->bus_master->write_bit(dev->bus_master->data, 1);
-               w1_delay(64);
-       } else {
+               w1_delay(55);
+       } else { // write 0
                dev->bus_master->write_bit(dev->bus_master->data, 0);
                w1_delay(60);
                dev->bus_master->write_bit(dev->bus_master->data, 1);
@@ -136,6 +136,11 @@
 {
        int i;

+       /* EK45 (add from datasheet)
+       The DS18B20 samples the 1-Wire bus during a window that lasts from 15µs to 60µs after the master
+       initiates the write time slot. If the bus is high during the sampling window, a 1 is written to the DS18B20.
+       If the line is low, a 0 is written to the DS18B20
+       */
        if (dev->bus_master->write_byte) {
                w1_pre_write(dev);
                dev->bus_master->write_byte(dev->bus_master->data, byte);
@@ -161,16 +166,24 @@
        unsigned long flags;

        /* sample timing is critical here */
+       /* EK45 add from datasheet
+       All read time slots must be a minimum of 60µs in duration with a minimum of a 1µs recovery time
+       between slots. A read time slot is initiated by the master device pulling the 1-Wire bus low for a
+       minimum of 1µs and then releasing the bus (see Figure 14). After the master initiates the read time slot,
+       the DS18B20 will begin transmitting a 1 or 0 on bus. The DS18B20 transmits a 1 by leaving the bus high
+       and transmits a 0 by pulling the bus low. When transmitting a 0, the DS18B20 will release the bus by the
+       end of the time slot, and the bus will be pulled back to its high idle state by the pullup resister. Output
+       data from the DS18B20 is valid for 15µs after the falling edge that initiated the read time slot. Therefore,
+       the master must release the bus and then sample the bus state within 15µs from the start of the slot.
+       */
        local_irq_save(flags);
        dev->bus_master->write_bit(dev->bus_master->data, 0);
-       w1_delay(6);
+       w1_delay(2);
        dev->bus_master->write_bit(dev->bus_master->data, 1);
-       w1_delay(9);
-
+       w1_delay(8);
        result = dev->bus_master->read_bit(dev->bus_master->data);
        local_irq_restore(flags);
-
-       w1_delay(55);
+       w1_delay(50);

        return result & 0x1;
 }
@@ -322,7 +335,6 @@
        if (dev->bus_master->reset_bus)
                result = dev->bus_master->reset_bus(dev->bus_master->data) & 0x1;
        else {
-               dev->bus_master->write_bit(dev->bus_master->data, 0);
                /* minimum 480, max ? us
                 * be nice and sleep, except 18b20 spec lists 960us maximum,
                 * so until we can sleep with microsecond accuracy, spin.
@@ -330,17 +342,27 @@
                 * cpu for such a short amount of time AND get it back in
                 * the maximum amount of time.
                 */
+
+               /* EK45 add from data sheet
+               During the initialization sequence the bus master transmits (TX) the reset pulse
+                by pulling the 1-Wire bus low for a minimum of 480µs.
+               The bus master then releases the bus and goes into receive mode (RX).
+               When the bus is released, the 5kΩ pullup resistor pulls the 1-Wire bus high.
+               When the DS18B20 detects this rising edge, it waits 15µs to 60µs and then transmits
+                a presence pulse by pulling the 1-Wire bus low for 60µs to 240µs
+               */
+               dev->bus_master->write_bit(dev->bus_master->data, 0);
                w1_delay(480);
                dev->bus_master->write_bit(dev->bus_master->data, 1);
                w1_delay(70);
-
                result = dev->bus_master->read_bit(dev->bus_master->data) & 0x1;
                /* minmum 70 (above) + 410 = 480 us
                 * There aren't any timing requirements between a reset and
                 * the following transactions.  Sleeping is safe here.
                 */
-               /* w1_delay(410); min required time */
-               msleep(1);
+
+               // EK45 edit 60µs + 240µs = 300µs (max)
+               w1_delay(410); // Rx max len = 480µs from datasheet
        }

        return result;
--- w1/slaves/w1_therm.c        2016-07-02 20:09:40.000000000 +0500
+++ w1.mod/slaves/w1_therm.c    2016-07-04 15:05:39.167831331 +0500
@@ -2,7 +2,7 @@
  *     w1_therm.c
  *
  * Copyright (c) 2004 Evgeniy Polyakov <zbr@ioremap.net>
- *
+ * Resolution modification by Evgeney Kirik <evgeney.kirik@gmail.com>
  *
  * 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
@@ -34,35 +34,33 @@
 #include "../w1_family.h"

 MODULE_LICENSE("GPL");
-MODULE_AUTHOR("Evgeniy Polyakov <zbr@ioremap.net>");
+MODULE_AUTHOR("Evgeniy Polyakov <zbr@ioremap.net> & EK45 <evgeney.kirik@gmail.com>");
 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);
+//#define W1_WRITE_SCRATCHPAD 0x4E // write scratchpad action byte

-static u8 bad_roms[][9] = {
-                               {0xaa, 0x00, 0x4b, 0x46, 0xff, 0xff, 0x0c, 0x10, 0x87},
-                               {}
-                       };
+u8 bit_res;
+unsigned int mct[4] = { 95, 190, 375, 750 }; // Max Conversion Time (bit res 9, 10, 11, 12)

-static ssize_t w1_therm_read(struct device *device,
-       struct device_attribute *attr, char *buf);
+static ssize_t w1_therm_read(struct device *device, struct device_attribute *attr, char *buf);
+static struct device_attribute w1_therm_attr = __ATTR(w1_slave, S_IRUGO, w1_therm_read, NULL);

-static struct device_attribute w1_therm_attr =
-       __ATTR(w1_slave, S_IRUGO, w1_therm_read, NULL);
+static ssize_t w1_resolution_set(struct device *device, struct device_attribute *attr, const char *buf, size_t count);
+static ssize_t w1_resolution_get(struct device *device, struct device_attribute *attr, char *buf);
+static struct device_attribute w1_therm_res = __ATTR(w1_resolution, S_IWUGO | S_IRUGO | S_IWGRP, w1_resolution_get, w1_resolution_set);

 static int w1_therm_add_slave(struct w1_slave *sl)
 {
-       return device_create_file(&sl->dev, &w1_therm_attr);
+       int ret;
+       ret = device_create_file(&sl->dev, &w1_therm_res); // add by EK45
+       ret += device_create_file(&sl->dev, &w1_therm_attr);
+
+       return ret;
 }

 static void w1_therm_remove_slave(struct w1_slave *sl)
 {
+       device_remove_file(&sl->dev, &w1_therm_res); // add by EK45
        device_remove_file(&sl->dev, &w1_therm_attr);
 }

@@ -159,105 +157,132 @@
        return 0;
 }

-static int w1_therm_check_rom(u8 rom[9])
+static ssize_t w1_resolution_set(struct device *device, struct device_attribute *attr, const char *buf, size_t count)
 {
-       int i;
+    struct w1_slave *sl = dev_to_w1_slave(device);
+    struct w1_master *dev = sl->master;
+    u8 scrpad[3];
+
+    if (buf[0] != 0) {
+       bit_res = 0; // 9 bit
+       if (buf[0] == '1') {
+           //dev_warn(device, "Set res to %dbit", bit_res + 9);
+           if (buf[1] == '0') bit_res = 1; // 10 bit
+           if (buf[1] == '1') bit_res = 2; // 11 bit
+           if (buf[1] == '2') bit_res = 3; // 12 bit
+       }

-       for (i=0; i<sizeof(bad_roms)/9; ++i)
-               if (!memcmp(bad_roms[i], rom, 9))
-                       return 1;
+       // Write resolution bit to Configuration Register
+       scrpad[2] = (((bit_res & 0x03) << 5) | 0x1F); // set bit res
+       scrpad[1] = 0; // write to eeprom
+       scrpad[0] = scrpad[2]; // write to scratchpad resolution set
+       if (!w1_reset_select_slave(sl)) {
+           w1_write_8(dev, W1_WRITE_SCRATCHPAD);
+           //w1_next_pullup(dev, 10);
+           w1_write_block(dev, scrpad, 3);
+           //dev_warn(device, "ds18x20 set res to %d\n", bit_res);
+       }
+    }

-       return 0;
+    return count;
 }

-static ssize_t w1_therm_read(struct device *device,
-       struct device_attribute *attr, char *buf)
+static ssize_t w1_resolution_get(struct device *device, struct device_attribute *attr, char *buf)
+{
+    struct w1_slave *sl = dev_to_w1_slave(device);
+    struct w1_master *dev = sl->master;
+    u8 rom[9];
+    ssize_t c = PAGE_SIZE;
+
+    bit_res=3; // Read conversion resolution from chip
+    if (!w1_reset_select_slave(sl)) {
+       w1_write_8(dev, W1_READ_SCRATCHPAD);
+       w1_read_block(dev, rom, 9);
+       bit_res = ((rom[4] & 0x60) >> 5);
+    }
+
+    c -= snprintf(buf + PAGE_SIZE - c, c, "%d\n", bit_res + 9);
+
+    return PAGE_SIZE - c;
+}
+
+static ssize_t w1_therm_read(struct device *device, struct device_attribute *attr, char *buf)
 {
        struct w1_slave *sl = dev_to_w1_slave(device);
        struct w1_master *dev = sl->master;
        u8 rom[9], crc, verdict, external_power;
-       int i, max_trying = 10;
+       int i, max_trying = 5;
        ssize_t c = PAGE_SIZE;

        i = mutex_lock_interruptible(&dev->mutex);
-       if (i != 0)
-               return i;
-
-       memset(rom, 0, sizeof(rom));
+       if (i != 0) return i;

        verdict = 0;
        crc = 0;

+       external_power = 1; // if normal power
+       if (!w1_reset_select_slave(sl)) {
+           w1_write_8(dev, W1_READ_PSUPPLY);
+           external_power = w1_read_8(dev);
+
+       }
+
+       bit_res=3; // Read conversion resolution from chip
+       if (!w1_reset_select_slave(sl)) {
+           w1_write_8(dev, W1_READ_SCRATCHPAD);
+           w1_read_block(dev, rom, 9);
+           bit_res = ((rom[4] & 0x60) >> 5);
+       }
+
        while (max_trying--) {
                if (!w1_reset_select_slave(sl)) {
                        int count = 0;
-                       unsigned int tm = 750;
+                       unsigned int tms = mct[bit_res]; // set timeout for xbit conversion
                        unsigned long sleep_rem;

-                       w1_write_8(dev, W1_READ_PSUPPLY);
-                       external_power = w1_read_8(dev);
-
-                       if (w1_reset_select_slave(sl))
-                               continue;
-
-                       /* 750ms strong pullup (or delay) after the convert */
-                       if (!external_power && w1_strong_pullup)
-                               w1_next_pullup(dev, tm);
+                       /* parasitic power delay after the convert */
+                       if (!external_power) // if parasitic power
+                           w1_next_pullup(dev, tms);

                        w1_write_8(dev, W1_CONVERT_TEMP);

-                       if (external_power) {
+                       if (external_power) { // if normal power
                                mutex_unlock(&dev->mutex);
-
-                               sleep_rem = msleep_interruptible(tm);
+                               sleep_rem = msleep_interruptible(tms);
                                if (sleep_rem != 0)
                                        return -EINTR;

                                i = mutex_lock_interruptible(&dev->mutex);
                                if (i != 0)
                                        return i;
-                       } else if (!w1_strong_pullup) {
-                               sleep_rem = msleep_interruptible(tm);
-                               if (sleep_rem != 0) {
-                                       mutex_unlock(&dev->mutex);
-                                       return -EINTR;
-                               }
                        }

-                       if (!w1_reset_select_slave(sl)) {
-
-                               w1_write_8(dev, W1_READ_SCRATCHPAD);
-                               if ((count = w1_read_block(dev, rom, 9)) != 9) {
-                                       dev_warn(device, "w1_read_block() "
-                                               "returned %u instead of 9.\n",
-                                               count);
-                               }
-
-                               crc = w1_calc_crc8(rom, 8);
+                       w1_reset_select_slave(sl);
+                       w1_write_8(dev, W1_READ_SCRATCHPAD);
+                       if ((count = w1_read_block(dev, rom, 9)) != 9) {
+                               //dev_warn(device, "w1_read_block() returned %u instead of 9.\n", count);
+                       }

-                               if (rom[8] == crc)
-                                       verdict = 1;
+                       crc = w1_calc_crc8(rom, 8);
+                       if (rom[8] == crc) {
+                           verdict = 1;
+                           break;
                        }
                }
-
-               if (!w1_therm_check_rom(rom))
-                       break;
        }

-       for (i = 0; i < 9; ++i)
-               c -= snprintf(buf + PAGE_SIZE - c, c, "%02x ", rom[i]);
-       c -= snprintf(buf + PAGE_SIZE - c, c, ": crc=%02x %s\n",
-                          crc, (verdict) ? "YES" : "NO");
+       for (i = 0; i < 9; ++i) c -= snprintf(buf + PAGE_SIZE - c, c, "%02x ", rom[i]);
+       c -= snprintf(buf + PAGE_SIZE - c, c, ": crc=%02x %s\n", crc, (verdict) ? "YES" : "NO");
+
        if (verdict)
                memcpy(sl->rom, rom, sizeof(sl->rom));
        else
-               dev_warn(device, "18S20 doesn't respond to CONVERT_TEMP.\n");
+               dev_warn(device, "ds18x20 doesn't respond to CONVERT_TEMP.\n");

-       for (i = 0; i < 9; ++i)
-               c -= snprintf(buf + PAGE_SIZE - c, c, "%02x ", sl->rom[i]);
+       for (i = 0; i < 9; ++i) c -= snprintf(buf + PAGE_SIZE - c, c, "%02x ", sl->rom[i]);
+       c -= snprintf(buf + PAGE_SIZE - c, c, "t=%d\n", w1_convert_temp(rom, sl->family->fid));
+       //c -= snprintf(buf + PAGE_SIZE - c, c, "Cycles=%d", 10-max_trying);

-       c -= snprintf(buf + PAGE_SIZE - c, c, "t=%d\n",
-               w1_convert_temp(rom, sl->family->fid));
        mutex_unlock(&dev->mutex);

        return PAGE_SIZE - c;

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is there any easy way for us - the non linux / C developers - to make our raspberry work with this module? the stantar response time of the default module is too much! is there any binary to overwrite the default w1_therm.ko file? or is there any instructions for to follow for patching the default module? thanks

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