w1_therm: adding alarm sysfs entry

commit e2c94d6f572079511945e64537eb1218643f2e68 upstream.

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.

A 'write_data' field is added in the device structure, to bind the
correct writing function, as some devices may have 2 or 3 bytes RAM.

Updating Documentation/ABI/testing/sysfs-driver-w1_therm accordingly.

Signed-off-by: Akira Shimahara <akira215corp@gmail.com>
Link: https://lore.kernel.org/r/20200511203801.411253-1-akira215corp@gmail.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/Documentation/ABI/testing/sysfs-driver-w1_therm b/Documentation/ABI/testing/sysfs-driver-w1_therm
index 6ffd3e3..f289520 100644 (file)
--- a/Documentation/ABI/testing/sysfs-driver-w1_therm
+++ b/Documentation/ABI/testing/sysfs-driver-w1_therm
@@ -1,3 +1,19 @@
+What:          /sys/bus/w1/devices/.../alarms
+Date:          May 2020
+Contact:       Akira Shimahara <akira215corp@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), if not values will be trimmed
+               to device min/max capabilities. Values are integer as they are
+               stored 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:          May 2020
 Contact:       Akira Shimahara <akira215corp@gmail.com>

diff --git a/drivers/w1/slaves/w1_therm.c b/drivers/w1/slaves/w1_therm.c
index 5a81ce2..8255361 100644 (file)
--- a/drivers/w1/slaves/w1_therm.c
+++ b/drivers/w1/slaves/w1_therm.c
@@ -58,6 +58,9 @@ module_param_named(strong_pullup, w1_strong_pullup, int, 0);
 #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 */
+
 /* Helpers Macros */
 
 /*
@@ -96,6 +99,7 @@ module_param_named(strong_pullup, w1_strong_pullup, int, 0);
  * @get_conversion_time: pointer to the device conversion time function
  * @set_resolution: pointer to the device set_resolution function
  * @get_resolution: pointer to the device get_resolution function
+ * @write_data: pointer to the device writing function (2 or 3 bytes)
  */
 struct w1_therm_family_converter {
        u8              broken;
@@ -105,6 +109,7 @@ struct w1_therm_family_converter {
        int             (*get_conversion_time)(struct w1_slave *sl);
        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);
 };
 
 /**
@@ -239,6 +244,12 @@ 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);
 
+static ssize_t alarms_store(struct device *device,
+       struct device_attribute *attr, const char *buf, size_t size);
+
+static ssize_t alarms_show(struct device *device,
+       struct device_attribute *attr, char *buf);
+
 /* Attributes declarations */
 
 static DEVICE_ATTR_RW(w1_slave);
@@ -247,6 +258,7 @@ 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 declaration */
 
@@ -278,6 +290,7 @@ static struct attribute *w1_therm_attrs[] = {
        &dev_attr_ext_power.attr,
        &dev_attr_resolution.attr,
        &dev_attr_eeprom.attr,
+       &dev_attr_alarms.attr,
        NULL,
 };
 
@@ -286,6 +299,7 @@ static struct attribute *w1_ds18s20_attrs[] = {
        &dev_attr_temperature.attr,
        &dev_attr_ext_power.attr,
        &dev_attr_eeprom.attr,
+       &dev_attr_alarms.attr,
        NULL,
 };
 
@@ -296,6 +310,7 @@ static struct attribute *w1_ds28ea00_attrs[] = {
        &dev_attr_ext_power.attr,
        &dev_attr_resolution.attr,
        &dev_attr_eeprom.attr,
+       &dev_attr_alarms.attr,
        NULL,
 };
 
@@ -556,6 +571,7 @@ static struct w1_therm_family_converter w1_therm_families[] = {
                .get_conversion_time    = w1_DS18S20_convert_time,
                .set_resolution         = NULL, /* no config register */
                .get_resolution         = NULL, /* no config register */
+               .write_data                     = w1_DS18S20_write_data,
        },
        {
                .f                              = &w1_therm_family_DS1822,
@@ -563,6 +579,7 @@ static struct w1_therm_family_converter w1_therm_families[] = {
                .get_conversion_time    = w1_DS18B20_convert_time,
                .set_resolution         = w1_DS18B20_set_resolution,
                .get_resolution         = w1_DS18B20_get_resolution,
+               .write_data                     = w1_DS18B20_write_data,
        },
        {
                .f                              = &w1_therm_family_DS18B20,
@@ -570,6 +587,7 @@ static struct w1_therm_family_converter w1_therm_families[] = {
                .get_conversion_time    = w1_DS18B20_convert_time,
                .set_resolution         = w1_DS18B20_set_resolution,
                .get_resolution         = w1_DS18B20_get_resolution,
+               .write_data                     = w1_DS18B20_write_data,
        },
        {
                .f                              = &w1_therm_family_DS28EA00,
@@ -577,6 +595,7 @@ static struct w1_therm_family_converter w1_therm_families[] = {
                .get_conversion_time    = w1_DS18B20_convert_time,
                .set_resolution         = w1_DS18B20_set_resolution,
                .get_resolution         = w1_DS18B20_get_resolution,
+               .write_data                     = w1_DS18B20_write_data,
        },
        {
                .f                              = &w1_therm_family_DS1825,
@@ -584,6 +603,7 @@ static struct w1_therm_family_converter w1_therm_families[] = {
                .get_conversion_time    = w1_DS18B20_convert_time,
                .set_resolution         = w1_DS18B20_set_resolution,
                .get_resolution         = w1_DS18B20_get_resolution,
+               .write_data                     = w1_DS18B20_write_data,
        }
 };
 
@@ -678,6 +698,26 @@ static inline int temperature_from_RAM(struct w1_slave *sl, u8 rom[9])
        return 0;  /* No device family */
 }
 
+/**
+ * int_to_short() - Safe casting of int to short
+ *
+ * @i: integer to be converted to short
+ *
+ * Device register use 1 byte to store signed integer.
+ * This helper function convert the int in a signed short,
+ * using the min/max values that device can measure as limits.
+ * min/max values are defined by macro.
+ *
+ * Return: a short in the range of min/max value
+ */
+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)
@@ -1251,6 +1291,127 @@ 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)