Patch for enhacement of w1_therm module. Adding bulk read support.
Sending a 'trigger' command in the dedicated sysfs entry of the bus master
device send a conversion command for all the slaves on the bus. The sysfs
entry is added as soon as at least one device supporting this feature
is detected on the bus.
A strong pull up is apply on the line if at least one device required it.
The duration of the pull up is the max time required by a device on the
line, which depends on the resolution settings of each device. The strong
pull up could be adjust with the a module parameter.
Updating documentation in Documentation/ABI/testing/sysfs-driver-w1_therm
and Documentation/w1/slaves/w1_therm.rst
Signed-off-by: Akira Shimahara <akira215c...@gmail.com>
---
.../ABI/testing/sysfs-driver-w1_therm | 36 ++-
Documentation/w1/slaves/w1_therm.rst | 50 +++-
drivers/w1/slaves/w1_therm.c | 217 +++++++++++++++++-
drivers/w1/slaves/w1_therm.h | 47 ++++
4 files changed, 335 insertions(+), 15 deletions(-)
diff --git a/Documentation/ABI/testing/sysfs-driver-w1_therm
b/Documentation/ABI/testing/sysfs-driver-w1_therm
index 39488a4..1f911ed 100644
--- a/Documentation/ABI/testing/sysfs-driver-w1_therm
+++ b/Documentation/ABI/testing/sysfs-driver-w1_therm
@@ -61,9 +61,16 @@ Date: Apr 2020
Contact: Akira Shimahara <akira215c...@gmail.com>
Description:
(RO) return the temperature in 1/1000 degC.
- Note that the conversion duration depend on the resolution (if
- device support this feature). It takes 94ms in 9bits
- resolution, 750ms for 12bits.
+ * If a bulk read has been triggered, it will directly
+ return the temperature computed when the bulk read
+ occurred, if available. If not yet available, nothing
+ is returned (a debug kernel message is sent), you
+ should retry later on.
+ * If no bulk read has been triggered, it will trigger
+ a conversion and send the result. Note that the
+ conversion duration depend on the resolution (if
+ device support this feature). It takes 94ms in 9bits
+ resolution, 750ms for 12bits.
Users: any user space application which wants to communicate with
w1_term device
@@ -84,4 +91,25 @@ Description:
refer to Documentation/w1/slaves/w1_therm.rst for detailed
information.
Users: any user space application which wants to communicate with
- w1_term device
\ No newline at end of file
+ w1_term device
+
+
+What: /sys/bus/w1/devices/w1_bus_masterXX/therm_bulk_read
+Date: Apr 2020
+Contact: Akira Shimahara <akira215c...@gmail.com>
+Description:
+ (RW) trigger a bulk read conversion. read the status
+ *read*:
+ * `-1`: conversion in progress on at least 1 sensor
+ * `1` : conversion complete but at least one sensor
+ value has not been read yet
+ * `0` : no bulk operation. Reading temperature will
+ trigger a conversion on each device
+ *write*: `trigger`: trigger a bulk read on all supporting
+ devices on the bus
+ Note that if a bulk read is sent but one sensor is not read
+ immediately, the next access to temperature on this device
+ will return the temperature measured at the time of issue
+ of the bulk read command (not the current temperature).
+Users: any user space application which wants to communicate with
+ w1_term device
diff --git a/Documentation/w1/slaves/w1_therm.rst
b/Documentation/w1/slaves/w1_therm.rst
index 82e8ffe..06eaff1 100644
--- a/Documentation/w1/slaves/w1_therm.rst
+++ b/Documentation/w1/slaves/w1_therm.rst
@@ -26,20 +26,31 @@ W1_THERM_DS1825 0x3B
W1_THERM_DS28EA00 0x42
==================== ====
-Support is provided through the sysfs w1_slave file. Each open and
+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
+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
+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) when reading values.
+Alternatively, temperature can be read using temperature sysfs, it
+return only temperature in millidegrees Centigrade.
+
+A bulk read of all devices on the bus could be done writing 'trigger'
+in the therm_bulk_read sysfs entry at w1_bus_master level. This will
+sent the convert command on all devices on the bus, and if parasite
+powered devices are detected on the bus (and strong pullup is enable
+in the module), it will drive the line high during the longer conversion
+time required by parasited powered device on the line. Reading
+therm_bulk_read will return 0 if no bulk conversion pending,
+-1 if at least one sensor still in conversion, 1 if conversion is complete
+but at least one sensor value has not been read yet. Result temperature is
+then accessed by reading the temperature sysfs entry of each device, which
+may return empty if conversion is still in progress. Note that if a bulk
+read is sent but one sensor is not read immediately, the next access to
+temperature on this device will return the temperature measured at the
+time of issue of the bulk read command (not the current temperature).
Writing a value between 9 and 12 to the sysfs w1_slave file will change the
precision of the sensor for the next readings. This value is in (volatile)
@@ -49,6 +60,27 @@ To store the current precision configuration into EEPROM,
the value 0
has to be written to the sysfs w1_slave file. Since the EEPROM has a limited
amount of writes (>50k), this command should be used wisely.
+Alternatively, resolution can be set or read (value from 9 to 12) using the
+dedicated resolution sysfs entry on each device. This sysfs entry is not
+present for devices not supporting this feature. Driver will adjust the
+correct conversion time for each device regarding to its resolution setting.
+In particular, strong pullup will be applied if required during the conversion
+duration.
+
+The write-only sysfs entry eeprom is an alternative for EEPROM operations:
+ * `save`: will save device RAM to EEPROM
+ * `restore`: will restore EEPROM data in device RAM.
+
+ext_power syfs entry allow tho check the power status of each device.
+ * `0`: device parasite powered
+ * `1`: device externally powered
+
+sysfs alarms allow read or write TH and TL (Temperature High an Low) alarms.
+Values shall be space separated and in the device range (typical -55 degC
+to 125 degC). Values are integer as they are store in a 8bit register in
+the device. Lowest value is automatically put to TL.Once set, alarms could
+be search at master level.
+
The module parameter strong_pullup can be set to 0 to disable the
strong pullup, 1 to enable autodetection or 2 to force strong pullup.
In case of autodetection, the driver will use the "READ POWER SUPPLY"
diff --git a/drivers/w1/slaves/w1_therm.c b/drivers/w1/slaves/w1_therm.c
index db75048..42b21fe 100644
--- a/drivers/w1/slaves/w1_therm.c
+++ b/drivers/w1/slaves/w1_therm.c
@@ -67,6 +67,15 @@ module_param_named(strong_pullup, w1_strong_pullup, int, 0);
* . 'restore' : restore EEPROM data in device RAM
* (device do that automatically on power-up)
*
+ * therm_bulk_read (RW): Attribute at master level
+ * . 'trigger' : trigger a bulk read on all supporting device on the bus
+ * read value:
+ * . -1 : conversion is in progress in 1 or more sensor
+ * . 1 : conversion complete but at least one sensor has not been read
+ * . 0 : no bulk operation. Reading temp will trigger a conversion
+ * caveat : if a bulk read is sent but one sensor is not read immediately,
+ * the next access to temperature will return the temperature measured
+ * at the time of issue of the bulk read command
*
* alarms (RW) : read TH and TL (Temperature High an Low) alarms
* Values shall be space separated and in the device range
@@ -225,6 +234,7 @@ static struct w1_therm_family_converter w1_therm_families[]
= {
.set_resolution = NULL, // no config register
.get_resolution = NULL, // no config register
.write_data = w1_DS18S20_write_data,
+ .bulk_read = true
},
{
.f = &w1_therm_family_DS1822,
@@ -233,6 +243,7 @@ static struct w1_therm_family_converter w1_therm_families[]
= {
.set_resolution = w1_DS18B20_set_resolution,
.get_resolution = w1_DS18B20_get_resolution,
.write_data = w1_DS18B20_write_data,
+ .bulk_read = true
},
{
.f = &w1_therm_family_DS18B20,
@@ -241,6 +252,7 @@ static struct w1_therm_family_converter w1_therm_families[]
= {
.set_resolution = w1_DS18B20_set_resolution,
.get_resolution = w1_DS18B20_get_resolution,
.write_data = w1_DS18B20_write_data,
+ .bulk_read = true
},
{
.f = &w1_therm_family_DS28EA00,
@@ -249,6 +261,7 @@ static struct w1_therm_family_converter w1_therm_families[]
= {
.set_resolution = w1_DS18B20_set_resolution,
.get_resolution = w1_DS18B20_get_resolution,
.write_data = w1_DS18B20_write_data,
+ .bulk_read = false
},
{
.f = &w1_therm_family_DS1825,
@@ -257,6 +270,7 @@ static struct w1_therm_family_converter w1_therm_families[]
= {
.set_resolution = w1_DS18B20_set_resolution,
.get_resolution = w1_DS18B20_get_resolution,
.write_data = w1_DS18B20_write_data,
+ .bulk_read = true
}
};
@@ -420,6 +434,18 @@ static inline bool bus_mutex_lock(struct mutex *lock)
return true;
}
+
+static inline bool bulk_read_support(struct w1_slave *sl)
+{
+ if (SLAVE_SPECIFIC_FUNC(sl))
+ return SLAVE_SPECIFIC_FUNC(sl)->bulk_read;
+
+ dev_info(&sl->dev,
+ "%s: Device not supported by the driver\n", __func__);
+
+ return false; /* No device family */
+}
+
static inline int conversion_time(struct w1_slave *sl)
{
if (SLAVE_SPECIFIC_FUNC(sl))
@@ -469,6 +495,24 @@ static int w1_therm_add_slave(struct w1_slave *sl)
return -ENODEV;
}
SLAVE_SPECIFIC_FUNC(sl) = sl_family_conv;
+
+ if (bulk_read_support(sl)) {
+ /* add the sys entry to trigger bulk_read
+ * at master level only the 1st time
+ */
+ if (!bulk_read_device_counter) {
+ int err = device_create_file(&sl->master->dev,
+ &dev_attr_therm_bulk_read);
+
+ if (err)
+ dev_warn(&sl->dev,
+ "%s: Device has been added, but bulk read is
unavailable. err=%d\n",
+ __func__, err);
+ }
+ /* Increment the counter */
+ bulk_read_device_counter++;
+ }
+
/* Getting the power mode of the device {external, parasite}*/
SLAVE_POWERMODE(sl) = read_powermode(sl);
@@ -491,6 +535,9 @@ static int w1_therm_add_slave(struct w1_slave *sl)
}
}
+ /* Finally initialize convert_triggered flag */
+ SLAVE_CONVERT_TRIGGERED(sl) = 0;
+
return 0;
}
@@ -498,6 +545,14 @@ static void w1_therm_remove_slave(struct w1_slave *sl)
{
int refcnt = atomic_sub_return(1, THERM_REFCNT(sl->family_data));
+ if (bulk_read_support(sl)) {
+ bulk_read_device_counter--;
+ /* Delete the entry if no more device support the feature */
+ if (!bulk_read_device_counter)
+ device_remove_file(&sl->master->dev,
+ &dev_attr_therm_bulk_read);
+ }
+
while (refcnt) {
msleep(1000);
refcnt = atomic_read(THERM_REFCNT(sl->family_data));
@@ -813,6 +868,94 @@ error:
return ret;
}
+static int trigger_bulk_read(struct w1_master *dev_master)
+{
+ struct w1_slave *sl = NULL; /* used to iterate through slaves */
+ int max_trying = W1_THERM_MAX_TRY;
+ int t_conv = 0;
+ int ret = -ENODEV;
+ bool strong_pullup = false;
+
+ /* Check whether there are parasite powered device on the bus,
+ * and compute duration of conversion for these devices
+ * so we can apply a strong pullup if required
+ */
+ list_for_each_entry(sl, &dev_master->slist, w1_slave_entry) {
+ if (!sl->family_data)
+ goto error;
+ if (bulk_read_support(sl)) {
+ int t_cur = conversion_time(sl);
+
+ t_conv = t_cur > t_conv ? t_cur : t_conv;
+ strong_pullup = strong_pullup ||
+ (w1_strong_pullup == 2 ||
+ (!SLAVE_POWERMODE(sl) &&
+ w1_strong_pullup));
+ }
+ }
+
+ /* t_conv is the max conversion time required on the bus
+ * If its 0, no device support the bulk read feature
+ */
+ if (!t_conv)
+ goto error;
+
+ if (!bus_mutex_lock(&dev_master->bus_mutex)) {
+ ret = -EAGAIN; // Didn't acquire the mutex
+ goto error;
+ }
+
+ while ((max_trying--) && (ret < 0)) { /* ret should be either 0 */
+
+ if (!w1_reset_bus(dev_master)) { /* Just reset the bus */
+ unsigned long sleep_rem;
+
+ w1_write_8(dev_master, W1_SKIP_ROM);
+
+ if (strong_pullup) /* Apply pullup if required */
+ w1_next_pullup(dev_master, t_conv);
+
+ w1_write_8(dev_master, W1_CONVERT_TEMP);
+
+ /* set a flag to instruct that converT pending */
+ list_for_each_entry(sl,
+ &dev_master->slist, w1_slave_entry) {
+ if (bulk_read_support(sl))
+ SLAVE_CONVERT_TRIGGERED(sl) = -1;
+ }
+
+ if (strong_pullup) { /*some device need pullup */
+ sleep_rem = msleep_interruptible(t_conv);
+ if (sleep_rem != 0) {
+ ret = -EINTR;
+ goto mt_unlock;
+ }
+ mutex_unlock(&dev_master->bus_mutex);
+ } else {
+ mutex_unlock(&dev_master->bus_mutex);
+ sleep_rem = msleep_interruptible(t_conv);
+ if (sleep_rem != 0) {
+ ret = -EINTR;
+ goto set_flag;
+ }
+ }
+ ret = 0;
+ goto set_flag;
+ }
+ }
+
+mt_unlock:
+ mutex_unlock(&dev_master->bus_mutex);
+set_flag:
+ /* set a flag to register convsersion is done */
+ list_for_each_entry(sl, &dev_master->slist, w1_slave_entry) {
+ if (bulk_read_support(sl))
+ SLAVE_CONVERT_TRIGGERED(sl) = 1;
+ }
+error:
+ return ret;
+}
+
/*------------------------Interface sysfs--------------------------*/
static ssize_t w1_slave_show(struct device *device,
@@ -824,7 +967,20 @@ static ssize_t w1_slave_show(struct device *device,
int ret, i;
ssize_t c = PAGE_SIZE;
- ret = convert_t(sl, &info);
+ if (bulk_read_support(sl)) {
+ if (SLAVE_CONVERT_TRIGGERED(sl) < 0) {
+ dev_dbg(device,
+ "%s: Conversion in progress, retry later\n",
+ __func__);
+ return 0;
+ } else if (SLAVE_CONVERT_TRIGGERED(sl) > 0) {
+ /* A bulk read has been issued, read the device RAM */
+ ret = read_scratchpad(sl, &info);
+ SLAVE_CONVERT_TRIGGERED(sl) = 0;
+ } else
+ ret = convert_t(sl, &info);
+ } else
+ ret = convert_t(sl, &info);
if (ret < 0) {
dev_dbg(device,
@@ -905,7 +1061,20 @@ static ssize_t temperature_show(struct device *device,
return 0; /* No device family */
}
- ret = convert_t(sl, &info);
+ if (bulk_read_support(sl)) {
+ if (SLAVE_CONVERT_TRIGGERED(sl) < 0) {
+ dev_dbg(device,
+ "%s: Conversion in progress, retry later\n",
+ __func__);
+ return 0;
+ } else if (SLAVE_CONVERT_TRIGGERED(sl) > 0) {
+ /* A bulk read has been issued, read the device RAM */
+ ret = read_scratchpad(sl, &info);
+ SLAVE_CONVERT_TRIGGERED(sl) = 0;
+ } else
+ ret = convert_t(sl, &info);
+ } else
+ ret = convert_t(sl, &info);
if (ret < 0) {
dev_dbg(device,
@@ -1138,6 +1307,50 @@ free_m:
return size;
}
+
+static ssize_t therm_bulk_read_store(struct device *device,
+ struct device_attribute *attr, const char *buf, size_t size)
+{
+ struct w1_master *dev_master = dev_to_w1_master(device);
+ int ret = -EINVAL; // Invalid argument
+
+ if (size == sizeof(BULK_TRIGGER_CMD))
+ if (!strncmp(buf, BULK_TRIGGER_CMD,
+ sizeof(BULK_TRIGGER_CMD)-1))
+ ret = trigger_bulk_read(dev_master);
+
+ if (ret)
+ dev_info(device,
+ "%s: unable to trigger a bulk read on the bus.
err=%d\n",
+ __func__, ret);
+
+ return size;
+}
+
+static ssize_t therm_bulk_read_show(struct device *device,
+ struct device_attribute *attr, char *buf)
+{
+ struct w1_master *dev_master = dev_to_w1_master(device);
+ struct w1_slave *sl = NULL;
+ int ret = 0;
+
+ list_for_each_entry(sl, &dev_master->slist, w1_slave_entry) {
+ if (sl->family_data) {
+ if (bulk_read_support(sl)) {
+ if (SLAVE_CONVERT_TRIGGERED(sl) == -1) {
+ ret = -1;
+ goto show_result;
+ }
+ if (SLAVE_CONVERT_TRIGGERED(sl) == 1)
+ /* continue to check other slaves */
+ ret = 1;
+ }
+ }
+ }
+show_result:
+ return sprintf(buf, "%d\n", ret);
+}
+
#if IS_REACHABLE(CONFIG_HWMON)
static int w1_read_temp(struct device *device, u32 attr, int channel,
long *val)
diff --git a/drivers/w1/slaves/w1_therm.h b/drivers/w1/slaves/w1_therm.h
index 4f2dcf0..93b1760 100644
--- a/drivers/w1/slaves/w1_therm.h
+++ b/drivers/w1/slaves/w1_therm.h
@@ -45,6 +45,9 @@
#define MIN_TEMP -55 /* min temperature that can be mesured */
#define MAX_TEMP 125 /* max temperature that can be mesured */
+/* Counter for devices supporting bulk reading */
+static u16 bulk_read_device_counter; // =0 as per C standard
+
/*----------------------------------Structs---------------------------------*/
/**
@@ -63,6 +66,7 @@ struct w1_therm_family_converter {
int (*set_resolution)(struct w1_slave *sl, int val);
int (*get_resolution)(struct w1_slave *sl);
int (*write_data)(struct w1_slave *sl, const u8 *data);
+ bool bulk_read;
};
/**
@@ -80,6 +84,7 @@ struct w1_therm_family_data {
atomic_t refcnt;
int external_powered;
int resolution;
+ int convert_triggered;
struct w1_therm_family_converter *specific_functions;
};
@@ -129,6 +134,15 @@ static inline int w1_DS18B20_get_resolution(struct
w1_slave *sl);
*/
#define SLAVE_RESOLUTION(sl) \
(((struct w1_therm_family_data *)(sl->family_data))->resolution)
+
+/* return whether or not a converT command has been issued to the slave
+ * 0: no bulk read is pending
+ * -1: conversion is in progress
+ * 1: conversion done, result to be read
+ */
+#define SLAVE_CONVERT_TRIGGERED(sl) \
+ (((struct w1_therm_family_data *)(sl->family_data))->convert_triggered)
+
/* return the address of the refcnt in the family data */
#define THERM_REFCNT(family_data) \
(&((struct w1_therm_family_data *)family_data)->refcnt)
@@ -149,6 +163,12 @@ static struct w1_therm_family_converter
*device_family(struct w1_slave *sl);
*/
static inline bool bus_mutex_lock(struct mutex *lock);
+/** support_bulk_read() check is device is supporting bulk read
+ * @param sl device to get the conversion time
+ * @return true : bulk read support, false : no support or error
+ */
+static inline bool bulk_read_support(struct w1_slave *sl);
+
/** conversion_time() get the Tconv fo the device
* @param sl device to get the conversion time
* @return conversion time in ms, negative values kernel error code
@@ -228,6 +248,15 @@ static int recall_eeprom(struct w1_slave *sl);
* <0 kernel error code
*/
static int read_powermode(struct w1_slave *sl);
+
+/** trigger_bulk_read()
+ * @brief send a SKIP ROM follow by a CONVERT T commmand
+ * on the bus. It also set a flag in each slave struct to signal
+ * @param dev_master the device master of the bus
+ * @return 0 if success, -kernel error code otherwise
+ */
+static int trigger_bulk_read(struct w1_master *dev_master);
+
/*----------------------------Interface sysfs-------------------------------*/
/** @brief A callback function to output the temperature Old way
@@ -298,6 +327,22 @@ static ssize_t alarms_store(struct device *device,
*/
static ssize_t alarms_show(struct device *device,
struct device_attribute *attr, char *buf);
+
+/** @brief A callback function to trigger bulk read on the bus
+ * @param check BULK_TRIGGER_CMD macro
+ */
+static ssize_t therm_bulk_read_store(struct device *device,
+ struct device_attribute *attr, const char *buf, size_t size);
+
+
+/** @brief A callback function to check if bulk read is on progress
+ * @return -1 conversion in progress
+ * 1 conversion complete but not read on all sensors
+ * 0 no bulk operation pending
+ */
+static ssize_t therm_bulk_read_show(struct device *device,
+ struct device_attribute *attr, char *buf);
+
/*-----------------------------Attributes declarations----------------------*/
static DEVICE_ATTR_RW(w1_slave);
@@ -308,6 +353,8 @@ static DEVICE_ATTR_RW(resolution);
static DEVICE_ATTR_WO(eeprom);
static DEVICE_ATTR_RW(alarms);
+static DEVICE_ATTR_RW(therm_bulk_read); /* attribut at master level */
+
/*--------------------------Interface Functions-----------------------------*/
/** w1_therm_add_slave() - Called each time a search discover a new device
--
2.25.4
