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-rw-r--r--target/linux/bcm27xx/patches-5.4/950-0769-w1_therm-adding-resolution-sysfs-entry.patch713
1 files changed, 713 insertions, 0 deletions
diff --git a/target/linux/bcm27xx/patches-5.4/950-0769-w1_therm-adding-resolution-sysfs-entry.patch b/target/linux/bcm27xx/patches-5.4/950-0769-w1_therm-adding-resolution-sysfs-entry.patch
new file mode 100644
index 0000000000..17b047a0c7
--- /dev/null
+++ b/target/linux/bcm27xx/patches-5.4/950-0769-w1_therm-adding-resolution-sysfs-entry.patch
@@ -0,0 +1,713 @@
+From feffc2efed02adda00c6c5480292db012663e6e8 Mon Sep 17 00:00:00 2001
+From: Akira Shimahara <akira215corp@gmail.com>
+Date: Mon, 11 May 2020 22:37:08 +0200
+Subject: [PATCH] w1_therm: adding resolution sysfs entry
+
+commit 308bdb94de0c1abe7eac5193f58638b8aeaddf4b upstream.
+
+Adding resolution sysfs entry (RW) to get or set the device resolution
+Write values are managed as follow:
+ * '9..12': resolution to set in bit
+ * Anything else: do nothing
+Read values are :
+ * '9..12': device resolution in bit
+ * '-xx': xx is kernel error when reading the resolution
+
+Only supported devices will show the sysfs entry. A new family has been
+created for DS18S20 devices as they do not implement resolution feature.
+
+The resolution of each device is check when the device is
+discover by the bus master, in 'w1_therm_add_slave(struct w1_slave *)'.
+The status is stored in the device structure w1_therm_family_data so
+that the driver always knows the resolution of each device, which could
+be used later to determine the required conversion duration (resolution
+dependent).
+
+The resolution is re evaluate each time a user read or write the sysfs
+entry.
+
+To avoid looping through the w1_therm_families at run time, the pointer
+'specific_functions' is set up to the correct 'w1_therm_family_converter'
+when the slave is added (which mean when it is discovered by the master).
+This initialization is done by a helper function
+'device_family(struct w1_slave *sl)', and a dedicated macro
+'SLAVE_SPECIFIC_FUNC(sl)' allow the access to the specific function of the
+slave device.
+
+'read_scratchpad' and 'write_scratchpad' are the hardware functions to
+access the device RAM, as per protocol specification.
+
+It cancel the former 'precision' functions, which was only set and never
+read (so not stored in the device struct).
+
+Updating Documentation/ABI/testing/sysfs-driver-w1_therm accordingly.
+
+Signed-off-by: Akira Shimahara <akira215corp@gmail.com>
+Link: https://lore.kernel.org/r/20200511203708.410649-1-akira215corp@gmail.com
+Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
+---
+ .../ABI/testing/sysfs-driver-w1_therm | 17 +
+ drivers/w1/slaves/w1_therm.c | 442 ++++++++++++++----
+ 2 files changed, 361 insertions(+), 98 deletions(-)
+
+--- a/Documentation/ABI/testing/sysfs-driver-w1_therm
++++ b/Documentation/ABI/testing/sysfs-driver-w1_therm
+@@ -10,6 +10,23 @@ Users: any user space application which
+ w1_term device
+
+
++What: /sys/bus/w1/devices/.../resolution
++Date: May 2020
++Contact: Akira Shimahara <akira215corp@gmail.com>
++Description:
++ (RW) get or set the device resolution (on supported devices,
++ if not, this entry is not present). Note that the resolution
++ will be changed only in device RAM, so it will be cleared when
++ power is lost. Trigger a 'save' to EEPROM command to keep
++ values after power-on. Read or write are :
++ * '9..12': device resolution in bit
++ or resolution to set in bit
++ * '-xx': xx is kernel error when reading the resolution
++ * Anything else: do nothing
++Users: any user space application which wants to communicate with
++ w1_term device
++
++
+ What: /sys/bus/w1/devices/.../w1_slave
+ Date: May 2020
+ Contact: Akira Shimahara <akira215corp@gmail.com>
+--- a/drivers/w1/slaves/w1_therm.c
++++ b/drivers/w1/slaves/w1_therm.c
+@@ -52,12 +52,26 @@ module_param_named(strong_pullup, w1_str
+ /* Helpers Macros */
+
+ /*
++ * return a pointer on the slave w1_therm_family_converter struct:
++ * always test family data existence before using this macro
++ */
++#define SLAVE_SPECIFIC_FUNC(sl) \
++ (((struct w1_therm_family_data *)(sl->family_data))->specific_functions)
++
++/*
+ * return the power mode of the sl slave : 1-ext, 0-parasite, <0 unknown
+ * always test family data existence before using this macro
+ */
+ #define SLAVE_POWERMODE(sl) \
+ (((struct w1_therm_family_data *)(sl->family_data))->external_powered)
+
++/*
++ * return the resolution in bit of the sl slave : <0 unknown
++ * always test family data existence before using this macro
++ */
++#define SLAVE_RESOLUTION(sl) \
++ (((struct w1_therm_family_data *)(sl->family_data))->resolution)
++
+ /* return the address of the refcnt in the family data */
+ #define THERM_REFCNT(family_data) \
+ (&((struct w1_therm_family_data *)family_data)->refcnt)
+@@ -70,7 +84,8 @@ module_param_named(strong_pullup, w1_str
+ * @reserved: not used here
+ * @f: pointer to the device binding structure
+ * @convert: pointer to the device conversion function
+- * @precision: pointer to the device precision function
++ * @set_resolution: pointer to the device set_resolution function
++ * @get_resolution: pointer to the device get_resolution function
+ * @eeprom: pointer to eeprom function
+ */
+ struct w1_therm_family_converter {
+@@ -78,7 +93,8 @@ struct w1_therm_family_converter {
+ u16 reserved;
+ struct w1_family *f;
+ int (*convert)(u8 rom[9]);
+- int (*precision)(struct device *device, int val);
++ int (*set_resolution)(struct w1_slave *sl, int val);
++ int (*get_resolution)(struct w1_slave *sl);
+ int (*eeprom)(struct device *device);
+ };
+
+@@ -89,11 +105,15 @@ struct w1_therm_family_converter {
+ * @external_powered: 1 device powered externally,
+ * 0 device parasite powered,
+ * -x error or undefined
++ * @resolution: current device resolution
++ * @specific_functions: pointer to struct of device specific function
+ */
+ struct w1_therm_family_data {
+ uint8_t rom[9];
+ atomic_t refcnt;
+ int external_powered;
++ int resolution;
++ struct w1_therm_family_converter *specific_functions;
+ };
+
+ /**
+@@ -127,6 +147,25 @@ struct therm_info {
+ static int reset_select_slave(struct w1_slave *sl);
+
+ /**
++ * read_scratchpad() - read the data in device RAM
++ * @sl: pointer to the slave to read
++ * @info: pointer to a structure to store the read results
++ *
++ * Return: 0 if success, -kernel error code otherwise
++ */
++static int read_scratchpad(struct w1_slave *sl, struct therm_info *info);
++
++/**
++ * write_scratchpad() - write nb_bytes in the device RAM
++ * @sl: pointer to the slave to write in
++ * @data: pointer to an array of 3 bytes, as 3 bytes MUST be written
++ * @nb_bytes: number of bytes to be written (2 for DS18S20, 3 otherwise)
++ *
++ * Return: 0 if success, -kernel error code otherwise
++ */
++static int write_scratchpad(struct w1_slave *sl, const u8 *data, u8 nb_bytes);
++
++/**
+ * read_powermode() - Query the power mode of the slave
+ * @sl: slave to retrieve the power mode
+ *
+@@ -154,11 +193,18 @@ static ssize_t w1_seq_show(struct device
+ static ssize_t ext_power_show(struct device *device,
+ struct device_attribute *attr, char *buf);
+
++static ssize_t resolution_show(struct device *device,
++ struct device_attribute *attr, char *buf);
++
++static ssize_t resolution_store(struct device *device,
++ struct device_attribute *attr, const char *buf, size_t size);
++
+ /* Attributes declarations */
+
+ static DEVICE_ATTR_RW(w1_slave);
+ static DEVICE_ATTR_RO(w1_seq);
+ static DEVICE_ATTR_RO(ext_power);
++static DEVICE_ATTR_RW(resolution);
+
+ /* Interface Functions declaration */
+
+@@ -187,6 +233,13 @@ static void w1_therm_remove_slave(struct
+ static struct attribute *w1_therm_attrs[] = {
+ &dev_attr_w1_slave.attr,
+ &dev_attr_ext_power.attr,
++ &dev_attr_resolution.attr,
++ NULL,
++};
++
++static struct attribute *w1_ds18s20_attrs[] = {
++ &dev_attr_w1_slave.attr,
++ &dev_attr_ext_power.attr,
+ NULL,
+ };
+
+@@ -194,12 +247,14 @@ static struct attribute *w1_ds28ea00_att
+ &dev_attr_w1_slave.attr,
+ &dev_attr_w1_seq.attr,
+ &dev_attr_ext_power.attr,
++ &dev_attr_resolution.attr,
+ NULL,
+ };
+
+ /* Attribute groups */
+
+ ATTRIBUTE_GROUPS(w1_therm);
++ATTRIBUTE_GROUPS(w1_ds18s20);
+ ATTRIBUTE_GROUPS(w1_ds28ea00);
+
+ #if IS_REACHABLE(CONFIG_HWMON)
+@@ -261,6 +316,13 @@ static struct w1_family_ops w1_therm_fop
+ .chip_info = W1_CHIPINFO,
+ };
+
++static struct w1_family_ops w1_ds18s20_fops = {
++ .add_slave = w1_therm_add_slave,
++ .remove_slave = w1_therm_remove_slave,
++ .groups = w1_ds18s20_groups,
++ .chip_info = W1_CHIPINFO,
++};
++
+ static struct w1_family_ops w1_ds28ea00_fops = {
+ .add_slave = w1_therm_add_slave,
+ .remove_slave = w1_therm_remove_slave,
+@@ -272,7 +334,7 @@ static struct w1_family_ops w1_ds28ea00_
+
+ static struct w1_family w1_therm_family_DS18S20 = {
+ .fid = W1_THERM_DS18S20,
+- .fops = &w1_therm_fops,
++ .fops = &w1_ds18s20_fops,
+ };
+
+ static struct w1_family w1_therm_family_DS18B20 = {
+@@ -300,92 +362,67 @@ static struct w1_family w1_therm_family_
+ /* write configuration to eeprom */
+ static inline int w1_therm_eeprom(struct device *device);
+
+-/* DS18S20 does not feature configuration register */
+-static inline int w1_DS18S20_precision(struct device *device, int val)
++static inline int w1_DS18B20_write_data(struct w1_slave *sl,
++ const u8 *data)
+ {
+- return 0;
++ return write_scratchpad(sl, data, 3);
+ }
+
+-/* Set precision for conversion */
+-static inline int w1_DS18B20_precision(struct device *device, int val)
++static inline int w1_DS18S20_write_data(struct w1_slave *sl,
++ const u8 *data)
+ {
+- struct w1_slave *sl = dev_to_w1_slave(device);
+- struct w1_master *dev = sl->master;
+- u8 rom[9], crc;
+- int ret, max_trying = 10;
+- u8 *family_data = sl->family_data;
+- uint8_t precision_bits;
+- uint8_t mask = 0x60;
+-
+- if (val > 12 || val < 9) {
+- pr_warn("Unsupported precision\n");
+- ret = -EINVAL;
+- goto error;
+- }
+-
+- if (!sl->family_data) {
+- ret = -ENODEV;
+- goto error;
+- }
+-
+- /* prevent the slave from going away in sleep */
+- atomic_inc(THERM_REFCNT(family_data));
++ /* No config register */
++ return write_scratchpad(sl, data, 2);
++}
+
+- ret = mutex_lock_interruptible(&dev->bus_mutex);
+- if (ret != 0)
+- goto dec_refcnt;
++static inline int w1_DS18B20_set_resolution(struct w1_slave *sl, int val)
++{
++ int ret = -ENODEV;
++ u8 new_config_register[3]; /* array of data to be written */
++ struct therm_info info;
+
+- memset(rom, 0, sizeof(rom));
++ /* resolution of DS18B20 is in the range [9..12] bits */
++ if (val < 9 || val > 12)
++ return -EINVAL;
++
++ val -= 9; /* soustract 9 the lowest resolution in bit */
++ val = (val << 5); /* shift to position bit 5 & bit 6 */
++
++ /*
++ * Read the scratchpad to change only the required bits
++ * (bit5 & bit 6 from byte 4)
++ */
++ ret = read_scratchpad(sl, &info);
++ if (!ret) {
++ new_config_register[0] = info.rom[2];
++ new_config_register[1] = info.rom[3];
++ /* config register is byte 4 & mask 0b10011111*/
++ new_config_register[2] = (info.rom[4] & 0x9F) |
++ (u8) val;
++ } else
++ return ret;
+
+- /* translate precision to bitmask (see datasheet page 9) */
+- switch (val) {
+- case 9:
+- precision_bits = 0x00;
+- break;
+- case 10:
+- precision_bits = 0x20;
+- break;
+- case 11:
+- precision_bits = 0x40;
+- break;
+- case 12:
+- default:
+- precision_bits = 0x60;
+- break;
+- }
++ /* Write data in the device RAM */
++ ret = w1_DS18B20_write_data(sl, new_config_register);
+
+- while (max_trying--) {
+- crc = 0;
++ return ret;
++}
+
+- if (!reset_select_slave(sl)) {
+- int count = 0;
++static inline int w1_DS18B20_get_resolution(struct w1_slave *sl)
++{
++ int ret = -ENODEV;
++ u8 config_register;
++ struct therm_info info;
+
+- /* read values to only alter precision bits */
+- w1_write_8(dev, W1_READ_SCRATCHPAD);
+- count = w1_read_block(dev, rom, 9);
+- if (count != 9)
+- dev_warn(device, "w1_read_block() returned %u instead of 9.\n", count);
+-
+- crc = w1_calc_crc8(rom, 8);
+- if (rom[8] == crc) {
+- rom[4] = (rom[4] & ~mask) | (precision_bits & mask);
+-
+- if (!reset_select_slave(sl)) {
+- w1_write_8(dev, W1_WRITE_SCRATCHPAD);
+- w1_write_8(dev, rom[2]);
+- w1_write_8(dev, rom[3]);
+- w1_write_8(dev, rom[4]);
++ ret = read_scratchpad(sl, &info);
+
+- break;
+- }
+- }
+- }
++ if (!ret) {
++ config_register = info.rom[4]; /* config register is byte 4 */
++ config_register &= 0x60; /* 0b01100000 keep only bit 5 & 6 */
++ config_register = (config_register >> 5); /* shift */
++ config_register += 9; /* add 9 the lowest resolution in bit */
++ ret = (int) config_register;
+ }
+-
+- mutex_unlock(&dev->bus_mutex);
+-dec_refcnt:
+- atomic_dec(THERM_REFCNT(family_data));
+-error:
+ return ret;
+ }
+
+@@ -438,31 +475,36 @@ static struct w1_therm_family_converter
+ {
+ .f = &w1_therm_family_DS18S20,
+ .convert = w1_DS18S20_convert_temp,
+- .precision = w1_DS18S20_precision,
++ .set_resolution = NULL, /* no config register */
++ .get_resolution = NULL, /* no config register */
+ .eeprom = w1_therm_eeprom
+ },
+ {
+ .f = &w1_therm_family_DS1822,
+ .convert = w1_DS18B20_convert_temp,
+- .precision = w1_DS18S20_precision,
++ .set_resolution = w1_DS18B20_set_resolution,
++ .get_resolution = w1_DS18B20_get_resolution,
+ .eeprom = w1_therm_eeprom
+ },
+ {
+ .f = &w1_therm_family_DS18B20,
+ .convert = w1_DS18B20_convert_temp,
+- .precision = w1_DS18B20_precision,
++ .set_resolution = w1_DS18B20_set_resolution,
++ .get_resolution = w1_DS18B20_get_resolution,
+ .eeprom = w1_therm_eeprom
+ },
+ {
+ .f = &w1_therm_family_DS28EA00,
+ .convert = w1_DS18B20_convert_temp,
+- .precision = w1_DS18S20_precision,
++ .set_resolution = w1_DS18B20_set_resolution,
++ .get_resolution = w1_DS18B20_get_resolution,
+ .eeprom = w1_therm_eeprom
+ },
+ {
+ .f = &w1_therm_family_DS1825,
+ .convert = w1_DS18B20_convert_temp,
+- .precision = w1_DS18S20_precision,
++ .set_resolution = w1_DS18B20_set_resolution,
++ .get_resolution = w1_DS18B20_get_resolution,
+ .eeprom = w1_therm_eeprom
+ }
+ };
+@@ -470,6 +512,26 @@ static struct w1_therm_family_converter
+ /* Helpers Functions */
+
+ /**
++ * device_family() - Retrieve a pointer on &struct w1_therm_family_converter
++ * @sl: slave to retrieve the device specific structure
++ *
++ * Return: pointer to the slaves's family converter, NULL if not known
++ */
++static struct w1_therm_family_converter *device_family(struct w1_slave *sl)
++{
++ struct w1_therm_family_converter *ret = NULL;
++ int i;
++
++ for (i = 0; i < ARRAY_SIZE(w1_therm_families); ++i) {
++ if (w1_therm_families[i].f->fid == sl->family->fid) {
++ ret = &w1_therm_families[i];
++ break;
++ }
++ }
++ return ret;
++}
++
++/**
+ * bus_mutex_lock() - Acquire the mutex
+ * @lock: w1 bus mutex to acquire
+ *
+@@ -522,6 +584,9 @@ static inline int w1_convert_temp(u8 rom
+
+ static int w1_therm_add_slave(struct w1_slave *sl)
+ {
++ struct w1_therm_family_converter *sl_family_conv;
++
++ /* Allocate memory */
+ sl->family_data = kzalloc(sizeof(struct w1_therm_family_data),
+ GFP_KERNEL);
+ if (!sl->family_data)
+@@ -529,6 +594,15 @@ static int w1_therm_add_slave(struct w1_
+
+ atomic_set(THERM_REFCNT(sl->family_data), 1);
+
++ /* Get a pointer to the device specific function struct */
++ sl_family_conv = device_family(sl);
++ if (!sl_family_conv) {
++ kfree(sl->family_data);
++ return -ENODEV;
++ }
++ /* save this pointer to the device structure */
++ SLAVE_SPECIFIC_FUNC(sl) = sl_family_conv;
++
+ /* Getting the power mode of the device {external, parasite} */
+ SLAVE_POWERMODE(sl) = read_powermode(sl);
+
+@@ -539,6 +613,18 @@ static int w1_therm_add_slave(struct w1_
+ __func__, SLAVE_POWERMODE(sl));
+ }
+
++ /* Getting the resolution of the device */
++ if (SLAVE_SPECIFIC_FUNC(sl)->get_resolution) {
++ SLAVE_RESOLUTION(sl) =
++ SLAVE_SPECIFIC_FUNC(sl)->get_resolution(sl);
++ if (SLAVE_RESOLUTION(sl) < 0) {
++ /* no error returned as device has been added */
++ dev_warn(&sl->dev,
++ "%s:Device has been added, but resolution may be corrupted. err=%d\n",
++ __func__, SLAVE_RESOLUTION(sl));
++ }
++ }
++
+ return 0;
+ }
+
+@@ -665,6 +751,93 @@ error:
+ return ret;
+ }
+
++static int read_scratchpad(struct w1_slave *sl, struct therm_info *info)
++{
++ struct w1_master *dev_master = sl->master;
++ int max_trying = W1_THERM_MAX_TRY;
++ int ret = -ENODEV;
++
++ info->verdict = 0;
++
++ if (!sl->family_data)
++ goto error;
++
++ memset(info->rom, 0, sizeof(info->rom));
++
++ /* prevent the slave from going away in sleep */
++ atomic_inc(THERM_REFCNT(sl->family_data));
++
++ if (!bus_mutex_lock(&dev_master->bus_mutex)) {
++ ret = -EAGAIN; /* Didn't acquire the mutex */
++ goto dec_refcnt;
++ }
++
++ while (max_trying-- && ret) { /* ret should be 0 */
++ /* safe version to select slave */
++ if (!reset_select_slave(sl)) {
++ u8 nb_bytes_read;
++
++ w1_write_8(dev_master, W1_READ_SCRATCHPAD);
++
++ nb_bytes_read = w1_read_block(dev_master, info->rom, 9);
++ if (nb_bytes_read != 9) {
++ dev_warn(&sl->dev,
++ "w1_read_block(): returned %u instead of 9.\n",
++ nb_bytes_read);
++ ret = -EIO;
++ }
++
++ info->crc = w1_calc_crc8(info->rom, 8);
++
++ if (info->rom[8] == info->crc) {
++ info->verdict = 1;
++ ret = 0;
++ } else
++ ret = -EIO; /* CRC not checked */
++ }
++
++ }
++ mutex_unlock(&dev_master->bus_mutex);
++
++dec_refcnt:
++ atomic_dec(THERM_REFCNT(sl->family_data));
++error:
++ return ret;
++}
++
++static int write_scratchpad(struct w1_slave *sl, const u8 *data, u8 nb_bytes)
++{
++ struct w1_master *dev_master = sl->master;
++ int max_trying = W1_THERM_MAX_TRY;
++ int ret = -ENODEV;
++
++ if (!sl->family_data)
++ goto error;
++
++ /* prevent the slave from going away in sleep */
++ atomic_inc(THERM_REFCNT(sl->family_data));
++
++ if (!bus_mutex_lock(&dev_master->bus_mutex)) {
++ ret = -EAGAIN; /* Didn't acquire the mutex */
++ goto dec_refcnt;
++ }
++
++ while (max_trying-- && ret) { /* ret should be 0 */
++ /* safe version to select slave */
++ if (!reset_select_slave(sl)) {
++ w1_write_8(dev_master, W1_WRITE_SCRATCHPAD);
++ w1_write_block(dev_master, data, nb_bytes);
++ ret = 0;
++ }
++ }
++ mutex_unlock(&dev_master->bus_mutex);
++
++dec_refcnt:
++ atomic_dec(THERM_REFCNT(sl->family_data));
++error:
++ return ret;
++}
++
+ static inline int w1_therm_eeprom(struct device *device)
+ {
+ struct w1_slave *sl = dev_to_w1_slave(device);
+@@ -815,26 +988,38 @@ static ssize_t w1_slave_store(struct dev
+ struct device_attribute *attr, const char *buf,
+ size_t size)
+ {
+- int val, ret;
++ int val, ret = 0;
+ struct w1_slave *sl = dev_to_w1_slave(device);
+- int i;
+
+- ret = kstrtoint(buf, 0, &val);
+- if (ret)
+- return ret;
++ ret = kstrtoint(buf, 10, &val); /* converting user entry to int */
+
+- for (i = 0; i < ARRAY_SIZE(w1_therm_families); ++i) {
+- if (w1_therm_families[i].f->fid == sl->family->fid) {
+- /* zero value indicates to write current configuration to eeprom */
+- if (val == 0)
+- ret = w1_therm_families[i].eeprom(device);
+- else
+- ret = w1_therm_families[i].precision(device,
+- val);
+- break;
+- }
++ if (ret) { /* conversion error */
++ dev_info(device,
++ "%s: conversion error. err= %d\n", __func__, ret);
++ return size; /* return size to avoid call back again */
++ }
++
++ if ((!sl->family_data) || (!SLAVE_SPECIFIC_FUNC(sl))) {
++ dev_info(device,
++ "%s: Device not supported by the driver\n", __func__);
++ return size; /* No device family */
++ }
++
++ if (val == 0) /* val=0 : trigger a EEPROM save */
++ ret = SLAVE_SPECIFIC_FUNC(sl)->eeprom(device);
++ else {
++ if (SLAVE_SPECIFIC_FUNC(sl)->set_resolution)
++ ret = SLAVE_SPECIFIC_FUNC(sl)->set_resolution(sl, val);
+ }
+- return ret ? : size;
++
++ if (ret) {
++ dev_info(device,
++ "%s: writing error %d\n", __func__, ret);
++ /* return size to avoid call back again */
++ } else
++ SLAVE_RESOLUTION(sl) = val;
++
++ return size; /* always return size to avoid infinite calling */
+ }
+
+ static ssize_t ext_power_show(struct device *device,
+@@ -859,6 +1044,67 @@ static ssize_t ext_power_show(struct dev
+ return sprintf(buf, "%d\n", SLAVE_POWERMODE(sl));
+ }
+
++static ssize_t resolution_show(struct device *device,
++ struct device_attribute *attr, char *buf)
++{
++ struct w1_slave *sl = dev_to_w1_slave(device);
++
++ if ((!sl->family_data) || (!SLAVE_SPECIFIC_FUNC(sl))) {
++ dev_info(device,
++ "%s: Device not supported by the driver\n", __func__);
++ return 0; /* No device family */
++ }
++
++ /* get the correct function depending on the device */
++ SLAVE_RESOLUTION(sl) = SLAVE_SPECIFIC_FUNC(sl)->get_resolution(sl);
++ if (SLAVE_RESOLUTION(sl) < 0) {
++ dev_dbg(device,
++ "%s: Resolution may be corrupted. err=%d\n",
++ __func__, SLAVE_RESOLUTION(sl));
++ }
++
++ return sprintf(buf, "%d\n", SLAVE_RESOLUTION(sl));
++}
++
++static ssize_t resolution_store(struct device *device,
++ struct device_attribute *attr, const char *buf, size_t size)
++{
++ struct w1_slave *sl = dev_to_w1_slave(device);
++ int val;
++ int ret = 0;
++
++ ret = kstrtoint(buf, 10, &val); /* converting user entry to int */
++
++ if (ret) { /* conversion error */
++ dev_info(device,
++ "%s: conversion error. err= %d\n", __func__, ret);
++ return size; /* return size to avoid call back again */
++ }
++
++ if ((!sl->family_data) || (!SLAVE_SPECIFIC_FUNC(sl))) {
++ dev_info(device,
++ "%s: Device not supported by the driver\n", __func__);
++ return size; /* No device family */
++ }
++
++ /*
++ * Don't deal with the val enterd by user,
++ * only device knows what is correct or not
++ */
++
++ /* get the correct function depending on the device */
++ ret = SLAVE_SPECIFIC_FUNC(sl)->set_resolution(sl, val);
++
++ if (ret) {
++ dev_info(device,
++ "%s: writing error %d\n", __func__, ret);
++ /* return size to avoid call back again */
++ } else
++ SLAVE_RESOLUTION(sl) = val;
++
++ return size;
++}
++
+ #if IS_REACHABLE(CONFIG_HWMON)
+ static int w1_read_temp(struct device *device, u32 attr, int channel,
+ long *val)