Commit 79c1cc1c authored by Robert Coulson's avatar Robert Coulson Committed by Guenter Roeck
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hwmon: (ds1621) Add ds1631 chip support to ds1621 driver and documentation 



Add definitions, information, and code for ds1631 chip support
to the ds1621 driver.

Signed-off-by: default avatarRobert Coulson <rob.coulson@gmail.com>
Signed-off-by: default avatarGuenter Roeck <linux@roeck-us.net>
parent 3a8fe331

Documentation/hwmon/ds1621

+24 −3
Original line number Diff line number Diff line
@@ -14,6 +14,11 @@ Supported chips: 
    Addresses scanned: I2C 0x48 - 0x4f

    Datasheet: Publicly available from www.datasheetarchive.com



  * Maxim Integrated DS1631

    Prefix: 'ds1631'

    Addresses scanned: I2C 0x48 - 0x4f

    Datasheet: Publicly available from www.maximintegrated.com



  * Maxim Integrated DS1721

    Prefix: 'ds1721'

    Addresses scanned: I2C 0x48 - 0x4f
@@ -69,7 +74,15 @@ Temperature conversion of the DS1621 takes up to 1000ms; internal access to 
non-volatile registers may last for 10ms or below.



The DS1625 is pin compatible and functionally equivalent with the DS1621,

but the DS1621 is meant to replace it.

but the DS1621 is meant to replace it. The DS1631 and DS1721 are also

pin compatible with the DS1621, but provide multi-resolution support.



Since there is no version register, there is no unique identification

for these devices. In addition, the DS1631 and DS1721 will emulate a

DS1621 device, if not explicitly instantiated (why? because the detect

function compares the temperature register values bits and checks for a

9-bit resolution). Therefore, for correct device identification and

functionality, explicit device instantiation is required.



The DS1721 is pin compatible with the DS1621, has an accuracy of +/- 1.0

degree Celsius over a -10 to +85 degree range, a minimum/maximum alarm
@@ -78,9 +91,17 @@ time of 750ms. 


In addition, the DS1721 supports four resolution settings from 9 to 12 bits

(defined in degrees C per LSB: 0.5, 0.25, 0.125, and 0.0625, respectifully),

that are set at device power on to the highest resolution: 12-bits (0.0625 degree C).

that are set at device power on to the highest resolution: 12-bits.



One additional note about the ds1721 is that although the data sheet says

the temperature flags (THF and TLF) are used internally, these flags do

get set and cleared as the actual temperature crosses the min or max settings.



The DS1631 is also pin compatible with the DS1621 and feature compatible with

the DS1721, however the DS1631 accuracy is +/- 0.5 degree Celsius over the

same range.



Changing the DS1721 resolution mode affects the conversion time and can be

Changing the DS1631/1721 resolution mode affects the conversion time and can be

done from userspace, via the device 'update_interval' sysfs attribute. This

attribute will normalize range of input values to the device maximum resolution

values defined in the datasheet as such:

drivers/hwmon/Kconfig

+1 −0
Original line number Diff line number Diff line
@@ -355,6 +355,7 @@ config SENSORS_DS1621 
	  Integrated DS1621 sensor chips and compatible models including:



	  - Dallas Semiconductor DS1625

	  - Maxim Integrated DS1631

	  - Maxim Integrated DS1721



	  This driver can also be built as a module.  If so, the module

drivers/hwmon/ds1621.c

+20 −7
Original line number Diff line number Diff line
@@ -10,8 +10,8 @@ 
 * resolution, a thermal alarm output (Tout), and user-defined minimum

 * and maximum temperature thresholds (TH and TL).

 *

 * The DS1625 and DS1721 are pin compatible with the DS1621 and similar

 * in operation, with slight variations as noted in the device

 * The DS1625, DS1631, and DS1721 are pin compatible with the DS1621 and

 * similar in operation, with slight variations as noted in the device

 * datasheets (please refer to www.maximintegrated.com for specific

 * device information).

 *
@@ -51,7 +51,7 @@ static const unsigned short normal_i2c[] = { 0x48, 0x49, 0x4a, 0x4b, 0x4c, 
					0x4d, 0x4e, 0x4f, I2C_CLIENT_END };



/* Supported devices */

enum chips { ds1621, ds1625, ds1721 };

enum chips { ds1621, ds1625, ds1631, ds1721 };



/* Insmod parameters */

static int polarity = -1;
@@ -69,6 +69,10 @@ MODULE_PARM_DESC(polarity, "Output's polarity: 0 = active high, 1 = active low") 
 *   7    6    5    4    3    2    1    0

 * |Done|THF |TLF |NVB | 1  | 0  |POL |1SHOT|

 *

 * - DS1631:

 *   7    6    5    4    3    2    1    0

 * |Done|THF |TLF |NVB | R1 | R0 |POL |1SHOT|

 *

 * - DS1721:

 *   7    6    5    4    3    2    1    0

 * |Done| X  | X  | U  | R1 | R0 |POL |1SHOT|
@@ -139,8 +143,8 @@ static inline int DS1621_TEMP_FROM_REG(u16 reg) 
/*

 * TEMP: 0.001C/bit (-55C to +125C)

 * REG:

 *  - 1621, 1625: x = 0.5C

 *  - 1721:       x = 0.0625C

 *  - 1621, 1625: 0.5C/bit

 *  - 1631, 1721: 0.0625C/bit

 * Assume highest resolution and let the bits fall where they may..

 */

static inline u16 DS1621_TEMP_TO_REG(long temp)
@@ -174,6 +178,7 @@ static void ds1621_init_client(struct i2c_client *client) 
		data->update_interval = DS1625_CONVERSION_MAX;

		sreg = DS1621_COM_START;

		break;

	case ds1631:

	case ds1721:

		resol = (new_conf & DS1621_REG_CONFIG_RESOL) >>

			 DS1621_REG_CONFIG_RESOL_SHIFT;
@@ -342,7 +347,7 @@ static umode_t ds1621_attribute_visible(struct kobject *kobj, 
	struct ds1621_data *data = i2c_get_clientdata(client);



	if (attr == &dev_attr_update_interval.attr)

		if (data->kind != ds1721)

		if (data->kind == ds1621 || data->kind == ds1625)

			/* shhh, we're hiding update_interval */

			return 0;

	return attr->mode;
@@ -376,7 +381,14 @@ static int ds1621_detect(struct i2c_client *client, 
	conf = i2c_smbus_read_byte_data(client, DS1621_REG_CONF);

	if (conf < 0 || conf & DS1621_REG_CONFIG_NVB)

		return -ENODEV;

	/* The 7 lowest bits of a temperature should always be 0. */

	/*

	 * The ds1621 & ds1625 use 9-bit resolution, so the 7 lowest bits

	 * of the temperature should always be 0 (NOTE: The other chips

	 * have multi-resolution support, so if they have 9-bit resolution

	 * configured and the min/max temperature values set accordingly,

	 * then if not explicitly instantiated, they *will* appear as and

	 * emulate a ds1621 device).

	 */

	for (i = 0; i < ARRAY_SIZE(DS1621_REG_TEMP); i++) {

		temp = i2c_smbus_read_word_data(client, DS1621_REG_TEMP[i]);

		if (temp < 0 || (temp & 0x7f00))
@@ -438,6 +450,7 @@ static int ds1621_remove(struct i2c_client *client) 
static const struct i2c_device_id ds1621_id[] = {

	{ "ds1621", ds1621 },

	{ "ds1625", ds1625 },

	{ "ds1631", ds1631 },

	{ "ds1721", ds1721 },

	{ }

};