w1_therm: adding ext_power sysfs entry (b7bb6ca1) · Commits · 戴 / test

Documentation/ABI/testing/sysfs-driver-w1_therm

+12 −0

Original line number	Diff line number	Diff line
		What: /sys/bus/w1/devices/.../ext_power
		Date: May 2020
		Contact: Akira Shimahara <akira215corp@gmail.com>
		Description:
		(RO) return the power status by asking the device
		* '0': device parasite powered
		* '1': device externally powered
		* '-xx': xx is kernel error when reading power status
		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>

drivers/w1/slaves/w1_therm.c

+137 −0

Original line number	Diff line number	Diff line
		@@ -43,8 +43,21 @@
		static int w1_strong_pullup = 1;
		module_param_named(strong_pullup, w1_strong_pullup, int, 0);

		/* Nb of try for an operation */
		#define W1_THERM_MAX_TRY 5

		/* ms delay to retry bus mutex */
		#define W1_THERM_RETRY_DELAY 20

		/* Helpers Macros */

		/*
		* 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 address of the refcnt in the family data */
		#define THERM_REFCNT(family_data) \
		(&((struct w1_therm_family_data *)family_data)->refcnt)
		@@ -73,10 +86,14 @@ struct w1_therm_family_converter {
		* struct w1_therm_family_data - device data
		* @rom: ROM device id (64bit Lasered ROM code + 1 CRC byte)
		* @refcnt: ref count
		* @external_powered: 1 device powered externally,
		* 0 device parasite powered,
		* -x error or undefined
		*/
		struct w1_therm_family_data {
		uint8_t rom[9];
		atomic_t refcnt;
		int external_powered;
		};

		/**
		@@ -109,6 +126,20 @@ struct therm_info {
		*/
		static int reset_select_slave(struct w1_slave *sl);

		/**
		* read_powermode() - Query the power mode of the slave
		* @sl: slave to retrieve the power mode
		*
		* Ask the device to get its power mode (external or parasite)
		* and store the power status in the &struct w1_therm_family_data.
		*
		* Return:
		* * 0 parasite powered device
		* * 1 externally powered device
		* * <0 kernel error code
		*/
		static int read_powermode(struct w1_slave *sl);

		/* Sysfs interface declaration */

		static ssize_t w1_slave_show(struct device *device,
		@@ -120,10 +151,14 @@ static ssize_t w1_slave_store(struct device *device,
		static ssize_t w1_seq_show(struct device *device,
		struct device_attribute attr, char buf);

		static ssize_t ext_power_show(struct device *device,
		struct device_attribute attr, char buf);

		/* Attributes declarations */

		static DEVICE_ATTR_RW(w1_slave);
		static DEVICE_ATTR_RO(w1_seq);
		static DEVICE_ATTR_RO(ext_power);

		/* Interface Functions declaration */

		@@ -151,12 +186,14 @@ static void w1_therm_remove_slave(struct w1_slave *sl);

		static struct attribute *w1_therm_attrs[] = {
		&dev_attr_w1_slave.attr,
		&dev_attr_ext_power.attr,
		NULL,
		};

		static struct attribute *w1_ds28ea00_attrs[] = {
		&dev_attr_w1_slave.attr,
		&dev_attr_w1_seq.attr,
		&dev_attr_ext_power.attr,
		NULL,
		};

		@@ -432,6 +469,34 @@ static struct w1_therm_family_converter w1_therm_families[] = {

		/* Helpers Functions */

		/**
		* bus_mutex_lock() - Acquire the mutex
		* @lock: w1 bus mutex to acquire
		*
		* It try to acquire the mutex W1_THERM_MAX_TRY times and wait
		* W1_THERM_RETRY_DELAY between 2 attempts.
		*
		* Return: true is mutex is acquired and lock, false otherwise
		*/
		static inline bool bus_mutex_lock(struct mutex *lock)
		{
		int max_trying = W1_THERM_MAX_TRY;

		/* try to acquire the mutex, if not, sleep retry_delay before retry) */
		while (mutex_lock_interruptible(lock) != 0 && max_trying > 0) {
		unsigned long sleep_rem;

		sleep_rem = msleep_interruptible(W1_THERM_RETRY_DELAY);
		if (!sleep_rem)
		max_trying--;
		}

		if (!max_trying)
		return false; /* Didn't acquire the bus mutex */

		return true;
		}

		/**
		* w1_convert_temp() - temperature conversion binding function
		* @rom: data read from device RAM (8 data bytes + 1 CRC byte)
		@@ -461,7 +526,19 @@ static int w1_therm_add_slave(struct w1_slave *sl)
		GFP_KERNEL);
		if (!sl->family_data)
		return -ENOMEM;

		atomic_set(THERM_REFCNT(sl->family_data), 1);

		/* Getting the power mode of the device {external, parasite} */
		SLAVE_POWERMODE(sl) = read_powermode(sl);

		if (SLAVE_POWERMODE(sl) < 0) {
		/* no error returned as device has been added */
		dev_warn(&sl->dev,
		"%s: Device has been added, but power_mode may be corrupted. err=%d\n",
		__func__, SLAVE_POWERMODE(sl));
		}

		return 0;
		}

		@@ -661,6 +738,44 @@ error:
		return ret;
		}

		static int read_powermode(struct w1_slave *sl)
		{
		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 < 0)) {
		/* safe version to select slave */
		if (!reset_select_slave(sl)) {
		w1_write_8(dev_master, W1_READ_PSUPPLY);
		/*
		* Emit a read time slot and read only one bit,
		* 1 is externally powered,
		* 0 is parasite powered
		*/
		ret = w1_touch_bit(dev_master, 1);
		/* ret should be either 1 either 0 */
		}
		}
		mutex_unlock(&dev_master->bus_mutex);

		dec_refcnt:
		atomic_dec(THERM_REFCNT(sl->family_data));
		error:
		return ret;
		}

		/* Sysfs Interface definition */

		static ssize_t w1_slave_show(struct device *device,
		@@ -722,6 +837,28 @@ static ssize_t w1_slave_store(struct device *device,
		return ret ? : size;
		}

		static ssize_t ext_power_show(struct device *device,
		struct device_attribute attr, char buf)
		{
		struct w1_slave *sl = dev_to_w1_slave(device);

		if (!sl->family_data) {
		dev_info(device,
		"%s: Device not supported by the driver\n", __func__);
		return 0; /* No device family */
		}

		/* Getting the power mode of the device {external, parasite} */
		SLAVE_POWERMODE(sl) = read_powermode(sl);

		if (SLAVE_POWERMODE(sl) < 0) {
		dev_dbg(device,
		"%s: Power_mode may be corrupted. err=%d\n",
		__func__, SLAVE_POWERMODE(sl));
		}
		return sprintf(buf, "%d\n", SLAVE_POWERMODE(sl));
		}

		#if IS_REACHABLE(CONFIG_HWMON)
		static int w1_read_temp(struct device *device, u32 attr, int channel,
		long *val)

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