Commit 92b8d272 authored by Akira Shimahara's avatar Akira Shimahara Committed by Greg Kroah-Hartman
Browse files

w1_therm: adding code comments and code reordering 



Adding code comments to split code in dedicated parts. After the global
declarations (defines, macros and function declarations), code is organized
as follow :
 - Device and family dependent structures and functions
 - Interfaces functions
 - Helpers functions
 - Hardware functions
 - Sysfs interface functions

Signed-off-by: default avatarAkira Shimahara <akira215corp@gmail.com>
Link: https://lore.kernel.org/r/20200511203535.409599-1-akira215corp@gmail.com


Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent 691e0f2c

drivers/w1/slaves/w1_therm.c

+259 −168
Original line number Diff line number Diff line
@@ -25,7 +25,8 @@ 
#define W1_THERM_DS1825		0x3B

#define W1_THERM_DS28EA00	0x42



/* Allow the strong pullup to be disabled, but default to enabled.

/*

 * Allow the strong pullup to be disabled, but default to enabled.

 * If it was disabled a parasite powered device might not get the require

 * current to do a temperature conversion.  If it is enabled parasite powered

 * devices have a better chance of getting the current required.
@@ -41,42 +42,55 @@ 
static int w1_strong_pullup = 1;

module_param_named(strong_pullup, w1_strong_pullup, int, 0);



/* Helpers Macros */



/* return the address of the refcnt in the family data */

#define THERM_REFCNT(family_data) \

	(&((struct w1_therm_family_data *)family_data)->refcnt)



/* Structs definition */



/**

 * struct w1_therm_family_converter - bind device specific functions

 * @broken: flag for non-registred families

 * @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

 * @eeprom: pointer to eeprom function

 */

struct w1_therm_family_converter {

	u8		broken;

	u16		reserved;

	struct w1_family	*f;

	int		(*convert)(u8 rom[9]);

	int		(*precision)(struct device *device, int val);

	int		(*eeprom)(struct device *device);

};



/**

 * struct w1_therm_family_data - device data

 * @rom: ROM device id (64bit Lasered ROM code + 1 CRC byte)

 * @refcnt: ref count

 */

struct w1_therm_family_data {

	uint8_t rom[9];

	atomic_t refcnt;

};



/**

 * struct therm_info - store temperature reading

 * @rom: read device data (8 data bytes + 1 CRC byte)

 * @crc: computed crc from rom

 * @verdict: 1 crc checked, 0 crc not matching

 */

struct therm_info {

	u8 rom[9];

	u8 crc;

	u8 verdict;

};



/* return the address of the refcnt in the family data */

#define THERM_REFCNT(family_data) \

	(&((struct w1_therm_family_data *)family_data)->refcnt)



static int w1_therm_add_slave(struct w1_slave *sl)

{

	sl->family_data = kzalloc(sizeof(struct w1_therm_family_data),

		GFP_KERNEL);

	if (!sl->family_data)

		return -ENOMEM;

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

	return 0;

}



static void w1_therm_remove_slave(struct w1_slave *sl)

{

	int refcnt = atomic_sub_return(1, THERM_REFCNT(sl->family_data));



	while (refcnt) {

		msleep(1000);

		refcnt = atomic_read(THERM_REFCNT(sl->family_data));

	}

	kfree(sl->family_data);

	sl->family_data = NULL;

}

/* Sysfs interface declaration */



static ssize_t w1_slave_show(struct device *device,

	struct device_attribute *attr, char *buf);
@@ -87,9 +101,35 @@ static ssize_t w1_slave_store(struct device *device, 
static ssize_t w1_seq_show(struct device *device,

	struct device_attribute *attr, char *buf);



/* Attributes declarations */



static DEVICE_ATTR_RW(w1_slave);

static DEVICE_ATTR_RO(w1_seq);



/* Interface Functions declaration */



/**

 * w1_therm_add_slave() - Called when a new slave is discovered

 * @sl: slave just discovered by the master.

 *

 * Called by the master when the slave is discovered on the bus. Used to

 * initialize slave state before the beginning of any communication.

 *

 * Return: 0 - If success, negative kernel code otherwise

 */

static int w1_therm_add_slave(struct w1_slave *sl);



/**

 * w1_therm_remove_slave() - Called when a slave is removed

 * @sl: slave to be removed.

 *

 * Called by the master when the slave is considered not to be on the bus

 * anymore. Used to free memory.

 */

static void w1_therm_remove_slave(struct w1_slave *sl);



/* Family attributes */



static struct attribute *w1_therm_attrs[] = {

	&dev_attr_w1_slave.attr,

	NULL,
@@ -101,6 +141,8 @@ static struct attribute *w1_ds28ea00_attrs[] = { 
	NULL,

};



/* Attribute groups */



ATTRIBUTE_GROUPS(w1_therm);

ATTRIBUTE_GROUPS(w1_ds28ea00);
@@ -154,6 +196,8 @@ static const struct hwmon_chip_info w1_chip_info = { 
#define W1_CHIPINFO	NULL

#endif



/* Family operations */



static struct w1_family_ops w1_therm_fops = {

	.add_slave	= w1_therm_add_slave,

	.remove_slave	= w1_therm_remove_slave,
@@ -168,6 +212,8 @@ static struct w1_family_ops w1_ds28ea00_fops = { 
	.chip_info	= W1_CHIPINFO,

};



/* Family binding operations struct */



static struct w1_family w1_therm_family_DS18S20 = {

	.fid = W1_THERM_DS18S20,

	.fops = &w1_therm_fops,
@@ -193,138 +239,18 @@ static struct w1_family w1_therm_family_DS1825 = { 
	.fops = &w1_therm_fops,

};



struct w1_therm_family_converter {

	u8			broken;

	u16			reserved;

	struct w1_family	*f;

	int			(*convert)(u8 rom[9]);

	int			(*precision)(struct device *device, int val);

	int			(*eeprom)(struct device *device);

};

/* Device dependent func */



/* write configuration to eeprom */

static inline int w1_therm_eeprom(struct device *device);



/* Set precision for conversion */

static inline int w1_DS18B20_precision(struct device *device, int val);

static inline int w1_DS18S20_precision(struct device *device, int val);



/* The return value is millidegrees Centigrade. */

static inline int w1_DS18B20_convert_temp(u8 rom[9]);

static inline int w1_DS18S20_convert_temp(u8 rom[9]);



static struct w1_therm_family_converter w1_therm_families[] = {

	{

		.f		= &w1_therm_family_DS18S20,

		.convert	= w1_DS18S20_convert_temp,

		.precision	= w1_DS18S20_precision,

		.eeprom		= w1_therm_eeprom

	},

	{

		.f		= &w1_therm_family_DS1822,

		.convert	= w1_DS18B20_convert_temp,

		.precision	= w1_DS18S20_precision,

		.eeprom		= w1_therm_eeprom

	},

	{

		.f		= &w1_therm_family_DS18B20,

		.convert	= w1_DS18B20_convert_temp,

		.precision	= w1_DS18B20_precision,

		.eeprom		= w1_therm_eeprom

	},

	{

		.f		= &w1_therm_family_DS28EA00,

		.convert	= w1_DS18B20_convert_temp,

		.precision	= w1_DS18S20_precision,

		.eeprom		= w1_therm_eeprom

	},

	{

		.f		= &w1_therm_family_DS1825,

		.convert	= w1_DS18B20_convert_temp,

		.precision	= w1_DS18S20_precision,

		.eeprom		= w1_therm_eeprom

	}

};



static inline int w1_therm_eeprom(struct device *device)

{

	struct w1_slave *sl = dev_to_w1_slave(device);

	struct w1_master *dev = sl->master;

	u8 rom[9], external_power;

	int ret, max_trying = 10;

	u8 *family_data = sl->family_data;



	if (!sl->family_data) {

		ret = -ENODEV;

		goto error;

	}



	/* prevent the slave from going away in sleep */

	atomic_inc(THERM_REFCNT(family_data));



	ret = mutex_lock_interruptible(&dev->bus_mutex);

	if (ret != 0)

		goto dec_refcnt;



	memset(rom, 0, sizeof(rom));



	while (max_trying--) {

		if (!w1_reset_select_slave(sl)) {

			unsigned int tm = 10;

			unsigned long sleep_rem;



			/* check if in parasite mode */

			w1_write_8(dev, W1_READ_PSUPPLY);

			external_power = w1_read_8(dev);



			if (w1_reset_select_slave(sl))

				continue;



			/* 10ms strong pullup/delay after the copy command */

			if (w1_strong_pullup == 2 ||

			    (!external_power && w1_strong_pullup))

				w1_next_pullup(dev, tm);



			w1_write_8(dev, W1_COPY_SCRATCHPAD);



			if (external_power) {

				mutex_unlock(&dev->bus_mutex);



				sleep_rem = msleep_interruptible(tm);

				if (sleep_rem != 0) {

					ret = -EINTR;

					goto dec_refcnt;

				}



				ret = mutex_lock_interruptible(&dev->bus_mutex);

				if (ret != 0)

					goto dec_refcnt;

			} else if (!w1_strong_pullup) {

				sleep_rem = msleep_interruptible(tm);

				if (sleep_rem != 0) {

					ret = -EINTR;

					goto mt_unlock;

				}

			}



			break;

		}

	}



mt_unlock:

	mutex_unlock(&dev->bus_mutex);

dec_refcnt:

	atomic_dec(THERM_REFCNT(family_data));

error:

	return ret;

}



/* DS18S20 does not feature configuration register */

static inline int w1_DS18S20_precision(struct device *device, int val)

{

	return 0;

}



/* Set precision for conversion */

static inline int w1_DS18B20_precision(struct device *device, int val)

{

	struct w1_slave *sl = dev_to_w1_slave(device);
@@ -407,6 +333,14 @@ error: 
	return ret;

}



/**

 * w1_DS18B20_convert_temp() - temperature computation for DS18B20

 * @rom: data read from device RAM (8 data bytes + 1 CRC byte)

 *

 * Can be called for any DS18B20 compliant device.

 *

 * Return: value in millidegrees Celsius.

 */

static inline int w1_DS18B20_convert_temp(u8 rom[9])

{

	s16 t = le16_to_cpup((__le16 *)rom);
@@ -414,6 +348,14 @@ static inline int w1_DS18B20_convert_temp(u8 rom[9]) 
	return t*1000/16;

}



/**

 * w1_DS18S20_convert_temp() - temperature computation for DS18S20

 * @rom: data read from device RAM (8 data bytes + 1 CRC byte)

 *

 * Can be called for any DS18S20 compliant device.

 *

 * Return: value in millidegrees Celsius.

 */

static inline int w1_DS18S20_convert_temp(u8 rom[9])

{

	int t, h;
@@ -434,6 +376,53 @@ static inline int w1_DS18S20_convert_temp(u8 rom[9]) 
	return t;

}



/* Device capability description */



static struct w1_therm_family_converter w1_therm_families[] = {

	{

		.f		= &w1_therm_family_DS18S20,

		.convert	= w1_DS18S20_convert_temp,

		.precision	= w1_DS18S20_precision,

		.eeprom		= w1_therm_eeprom

	},

	{

		.f		= &w1_therm_family_DS1822,

		.convert	= w1_DS18B20_convert_temp,

		.precision	= w1_DS18S20_precision,

		.eeprom		= w1_therm_eeprom

	},

	{

		.f		= &w1_therm_family_DS18B20,

		.convert	= w1_DS18B20_convert_temp,

		.precision	= w1_DS18B20_precision,

		.eeprom		= w1_therm_eeprom

	},

	{

		.f		= &w1_therm_family_DS28EA00,

		.convert	= w1_DS18B20_convert_temp,

		.precision	= w1_DS18S20_precision,

		.eeprom		= w1_therm_eeprom

	},

	{

		.f		= &w1_therm_family_DS1825,

		.convert	= w1_DS18B20_convert_temp,

		.precision	= w1_DS18S20_precision,

		.eeprom		= w1_therm_eeprom

	}

};



/* Helpers Functions */



/**

 * w1_convert_temp() - temperature conversion binding function

 * @rom: data read from device RAM (8 data bytes + 1 CRC byte)

 * @fid: device family id

 *

 * The function call the temperature computation function according to

 * device family.

 *

 * Return: value in millidegrees Celsius.

 */

static inline int w1_convert_temp(u8 rom[9], u8 fid)

{

	int i;
@@ -445,31 +434,32 @@ static inline int w1_convert_temp(u8 rom[9], u8 fid) 
	return 0;

}



static ssize_t w1_slave_store(struct device *device,

			      struct device_attribute *attr, const char *buf,

			      size_t size)

/* Interface Functions */



static int w1_therm_add_slave(struct w1_slave *sl)

{

	int val, ret;

	struct w1_slave *sl = dev_to_w1_slave(device);

	int i;

	sl->family_data = kzalloc(sizeof(struct w1_therm_family_data),

		GFP_KERNEL);

	if (!sl->family_data)

		return -ENOMEM;

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

	return 0;

}



	ret = kstrtoint(buf, 0, &val);

	if (ret)

		return ret;

static void w1_therm_remove_slave(struct w1_slave *sl)

{

	int refcnt = atomic_sub_return(1, THERM_REFCNT(sl->family_data));



	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;

		}

	while (refcnt) {

		msleep(1000);

		refcnt = atomic_read(THERM_REFCNT(sl->family_data));

	}

	return ret ? : size;

	kfree(sl->family_data);

	sl->family_data = NULL;

}



/* Hardware Functions */



static ssize_t read_therm(struct device *device,

			  struct w1_slave *sl, struct therm_info *info)

{
@@ -564,6 +554,81 @@ error: 
	return ret;

}



static inline int w1_therm_eeprom(struct device *device)

{

	struct w1_slave *sl = dev_to_w1_slave(device);

	struct w1_master *dev = sl->master;

	u8 rom[9], external_power;

	int ret, max_trying = 10;

	u8 *family_data = sl->family_data;



	if (!sl->family_data) {

		ret = -ENODEV;

		goto error;

	}



	/* prevent the slave from going away in sleep */

	atomic_inc(THERM_REFCNT(family_data));



	ret = mutex_lock_interruptible(&dev->bus_mutex);

	if (ret != 0)

		goto dec_refcnt;



	memset(rom, 0, sizeof(rom));



	while (max_trying--) {

		if (!w1_reset_select_slave(sl)) {

			unsigned int tm = 10;

			unsigned long sleep_rem;



			/* check if in parasite mode */

			w1_write_8(dev, W1_READ_PSUPPLY);

			external_power = w1_read_8(dev);



			if (w1_reset_select_slave(sl))

				continue;



			/* 10ms strong pullup/delay after the copy command */

			if (w1_strong_pullup == 2 ||

			    (!external_power && w1_strong_pullup))

				w1_next_pullup(dev, tm);



			w1_write_8(dev, W1_COPY_SCRATCHPAD);



			if (external_power) {

				mutex_unlock(&dev->bus_mutex);



				sleep_rem = msleep_interruptible(tm);

				if (sleep_rem != 0) {

					ret = -EINTR;

					goto dec_refcnt;

				}



				ret = mutex_lock_interruptible(&dev->bus_mutex);

				if (ret != 0)

					goto dec_refcnt;

			} else if (!w1_strong_pullup) {

				sleep_rem = msleep_interruptible(tm);

				if (sleep_rem != 0) {

					ret = -EINTR;

					goto mt_unlock;

				}

			}



			break;

		}

	}



mt_unlock:

	mutex_unlock(&dev->bus_mutex);

dec_refcnt:

	atomic_dec(THERM_REFCNT(family_data));

error:

	return ret;

}



/* Sysfs Interface definition */



static ssize_t w1_slave_show(struct device *device,

			     struct device_attribute *attr, char *buf)

{
@@ -597,6 +662,32 @@ static ssize_t w1_slave_show(struct device *device, 
	return ret;

}



static ssize_t w1_slave_store(struct device *device,

			      struct device_attribute *attr, const char *buf,

			      size_t size)

{

	int val, ret;

	struct w1_slave *sl = dev_to_w1_slave(device);

	int i;



	ret = kstrtoint(buf, 0, &val);

	if (ret)

		return ret;



	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;

		}

	}

	return ret ? : size;

}



#if IS_REACHABLE(CONFIG_HWMON)

static int w1_read_temp(struct device *device, u32 attr, int channel,

			long *val)

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