Adding device alarms settings by a dedicated sysfs entry alarms (RW):
read or write TH and TL in the device RAM. Checking devices in alarm
state could be performed using the master search command.
As alarms temperature level are store in a 8 bit register on the device
and are signed values, a safe cast shall be performed using the min and
max temperature that device are able to measure. This is done by
int_to_short inline function.
Updating doc in Documentation/ABI/testing/sysfs-driver-w1_therm
accordingly.
Signed-off-by: Akira Shimahara <akira215c...@gmail.com>
---
.../ABI/testing/sysfs-driver-w1_therm | 15 ++
drivers/w1/slaves/w1_therm.c | 138 ++++++++++++++++++
drivers/w1/slaves/w1_therm.h | 22 +++
3 files changed, 175 insertions(+)
diff --git a/Documentation/ABI/testing/sysfs-driver-w1_therm
b/Documentation/ABI/testing/sysfs-driver-w1_therm
index 279e13d..39488a4 100644
--- a/Documentation/ABI/testing/sysfs-driver-w1_therm
+++ b/Documentation/ABI/testing/sysfs-driver-w1_therm
@@ -1,3 +1,18 @@
+What: /sys/bus/w1/devices/.../alarms
+Date: Apr 2020
+Contact: Akira Shimahara <akira215c...@gmail.com>
+Description:
+ (RW) 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, refer to
+ Documentation/w1/w1_generic.rst for detailed information
+Users: any user space application which wants to communicate with
+ w1_term device
+
+
What: /sys/bus/w1/devices/.../eeprom
Date: Apr 2020
Contact: Akira Shimahara <akira215c...@gmail.com>
diff --git a/drivers/w1/slaves/w1_therm.c b/drivers/w1/slaves/w1_therm.c
index 2c89d9f..90217b1 100644
--- a/drivers/w1/slaves/w1_therm.c
+++ b/drivers/w1/slaves/w1_therm.c
@@ -68,6 +68,12 @@ module_param_named(strong_pullup, w1_strong_pullup, int, 0);
* (device do that automatically on power-up)
*
*
+ * alarms (RW) : read TH and TL (Temperature High an Low) alarms
+ * Values shall be space separated and in the device range
+ * (typically -55° to 125°)
+ * Values are integer are they are store in a 8bit field in the device
+ * Lowest value is automatically put to TL
+ *
*/
/*
@@ -81,6 +87,7 @@ static struct attribute *w1_therm_attrs[] = {
&dev_attr_ext_power.attr,
&dev_attr_resolution.attr,
&dev_attr_eeprom.attr,
+ &dev_attr_alarms.attr,
NULL,
};
@@ -89,6 +96,7 @@ static struct attribute *w1_ds18s20_attrs[] = {
&dev_attr_temperature.attr,
&dev_attr_ext_power.attr,
&dev_attr_eeprom.attr,
+ &dev_attr_alarms.attr,
NULL,
};
@@ -99,6 +107,7 @@ static struct attribute *w1_ds28ea00_attrs[] = {
&dev_attr_ext_power.attr,
&dev_attr_resolution.attr,
&dev_attr_eeprom.attr,
+ &dev_attr_alarms.attr,
NULL,
};
@@ -206,6 +215,7 @@ static struct w1_family w1_therm_family_DS1825 = {
};
/*----------------------Device capability description-----------------------*/
+
static struct w1_therm_family_converter w1_therm_families[] = {
{
.f = &w1_therm_family_DS18S20,
@@ -431,6 +441,14 @@ static inline int temperature_from_RAM(struct w1_slave
*sl, u8 rom[9])
return 0; /* No device family */
}
+static inline s8 int_to_short(int i)
+{
+ /* Prepare to cast to short by eliminating out of range values */
+ i = i > MAX_TEMP ? MAX_TEMP : i;
+ i = i < MIN_TEMP ? MIN_TEMP : i;
+ return (s8) i;
+}
+
/*-------------------------Interface Functions------------------------------*/
static int w1_therm_add_slave(struct w1_slave *sl)
@@ -1000,6 +1018,126 @@ static ssize_t eeprom_store(struct device *device,
return size;
}
+static ssize_t alarms_show(struct device *device,
+ struct device_attribute *attr, char *buf)
+{
+ struct w1_slave *sl = dev_to_w1_slave(device);
+ int ret = -ENODEV;
+ s8 th = 0, tl = 0;
+ struct therm_info scratchpad;
+
+ ret = read_scratchpad(sl, &scratchpad);
+
+ if (!ret) {
+ th = scratchpad.rom[2]; // TH is byte 2
+ tl = scratchpad.rom[3]; // TL is byte 3
+ } else {
+ dev_info(device,
+ "%s: error reading alarms register %d\n",
+ __func__, ret);
+ }
+
+ return sprintf(buf, "%hd %hd\n", tl, th);
+}
+
+static ssize_t alarms_store(struct device *device,
+ struct device_attribute *attr, const char *buf, size_t size)
+{
+ struct w1_slave *sl = dev_to_w1_slave(device);
+ struct therm_info info;
+ u8 new_config_register[3]; /* array of data to be written */
+ int temp, ret = -EINVAL;
+ char *token = NULL;
+ s8 tl, th, tt; /* 1 byte per value + temp ring order */
+ char *p_args = kmalloc(size, GFP_KERNEL);
+
+ /* Safe string copys as buf is const */
+ if (!p_args) {
+ dev_warn(device,
+ "%s: error unable to allocate memory %d\n",
+ __func__, -ENOMEM);
+ return size;
+ }
+ strcpy(p_args, buf);
+
+ /* Split string using space char */
+ token = strsep(&p_args, " ");
+
+ if (!token) {
+ dev_info(device,
+ "%s: error parsing args %d\n", __func__, -EINVAL);
+ goto free_m;
+ }
+
+ /* Convert 1st entry to int */
+ ret = kstrtoint (token, 10, &temp);
+ if (ret) {
+ dev_info(device,
+ "%s: error parsing args %d\n", __func__, ret);
+ goto free_m;
+ }
+
+ tl = int_to_short(temp);
+
+ /* Split string using space char */
+ token = strsep(&p_args, " ");
+ if (!token) {
+ dev_info(device,
+ "%s: error parsing args %d\n", __func__, -EINVAL);
+ goto free_m;
+ }
+ /* Convert 2nd entry to int */
+ ret = kstrtoint (token, 10, &temp);
+ if (ret) {
+ dev_info(device,
+ "%s: error parsing args %d\n", __func__, ret);
+ goto free_m;
+ }
+
+ /* Prepare to cast to short by eliminating out of range values */
+ th = int_to_short(temp);
+
+ /* Reorder if required th and tl */
+ if (tl > th) {
+ tt = tl; tl = th; th = tt;
+ }
+
+ /* Read the scratchpad to change only the required bits
+ * (th : byte 2 - tl: byte 3)
+ */
+ ret = read_scratchpad(sl, &info);
+ if (!ret) {
+ new_config_register[0] = th; // Byte 2
+ new_config_register[1] = tl; // Byte 3
+ new_config_register[2] = info.rom[4];// Byte 4
+ } else {
+ dev_info(device,
+ "%s: error reading from the slave device %d\n",
+ __func__, ret);
+ goto free_m;
+ }
+
+ /* Write data in the device RAM */
+ if (!SLAVE_SPECIFIC_FUNC(sl)) {
+ dev_info(device,
+ "%s: Device not supported by the driver %d\n",
+ __func__, -ENODEV);
+ goto free_m;
+ }
+
+ ret = SLAVE_SPECIFIC_FUNC(sl)->write_data(sl, new_config_register);
+ if (ret)
+ dev_info(device,
+ "%s: error writing to the slave device %d\n",
+ __func__, ret);
+
+free_m:
+ /* free allocated memory */
+ kfree(p_args);
+
+ return size;
+}
+
#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 6929991..d4c560a 100644
--- a/drivers/w1/slaves/w1_therm.h
+++ b/drivers/w1/slaves/w1_therm.h
@@ -40,6 +40,9 @@
#define EEPROM_CMD_WRITE "save" /* cmd for write eeprom sysfs */
#define EEPROM_CMD_READ "restore" /* cmd for read eeprom sysfs */
+#define MIN_TEMP -55 /* min temperature that can be mesured */
+#define MAX_TEMP 125 /* max temperature that can be mesured */
+
/*----------------------------------Structs---------------------------------*/
/**
@@ -159,6 +162,13 @@ static inline int conversion_time(struct w1_slave *sl);
*/
static inline int temperature_from_RAM(struct w1_slave *sl, u8 rom[9]);
+/** int_to_short() safe casting of int to short
+ * min/max values are defined by macro
+ * @param i integer to be converted to short
+ * @return a short in the range of min/max value
+ */
+static inline s8 int_to_short(int i);
+
/*---------------------------Hardware Functions-----------------------------*/
/**
@@ -277,6 +287,17 @@ static ssize_t resolution_store(struct device *device,
static ssize_t eeprom_store(struct device *device,
struct device_attribute *attr, const char *buf, size_t size);
+/** @brief A callback function to set the alarms level
+ * @param device represents the master device
+ */
+static ssize_t alarms_store(struct device *device,
+ struct device_attribute *attr, const char *buf, size_t size);
+
+/** @brief A callback function to get the alarms level
+ * @return Low and High alarm, separate by one space
+ */
+static ssize_t alarms_show(struct device *device,
+ struct device_attribute *attr, char *buf);
/*-----------------------------Attributes declarations----------------------*/
static DEVICE_ATTR_RW(w1_slave);
@@ -285,6 +306,7 @@ static DEVICE_ATTR_RO(temperature);
static DEVICE_ATTR_RO(ext_power);
static DEVICE_ATTR_RW(resolution);
static DEVICE_ATTR_WO(eeprom);
+static DEVICE_ATTR_RW(alarms);
/*--------------------------Interface Functions-----------------------------*/
--
2.26.2
