About Kernel Documentation Linux Kernel Contact Linux Resources Linux Blog

Documentation / hwmon / lm93




Custom Search

Based on kernel version 3.16. Page generated on 2014-08-06 21:39 EST.

1	Kernel driver lm93
2	==================
3	
4	Supported chips:
5	  * National Semiconductor LM93
6	    Prefix 'lm93'
7	    Addresses scanned: I2C 0x2c-0x2e
8	    Datasheet: http://www.national.com/ds.cgi/LM/LM93.pdf
9	  * National Semiconductor LM94
10	    Prefix 'lm94'
11	    Addresses scanned: I2C 0x2c-0x2e
12	    Datasheet: http://www.national.com/ds.cgi/LM/LM94.pdf
13	
14	Authors:
15		Mark M. Hoffman <mhoffman@lightlink.com>
16		Ported to 2.6 by Eric J. Bowersox <ericb@aspsys.com>
17		Adapted to 2.6.20 by Carsten Emde <ce@osadl.org>
18		Modified for mainline integration by Hans J. Koch <hjk@hansjkoch.de>
19	
20	Module Parameters
21	-----------------
22	
23	* init: integer
24	  Set to non-zero to force some initializations (default is 0).
25	* disable_block: integer
26	  A "0" allows SMBus block data transactions if the host supports them.  A "1"
27	  disables SMBus block data transactions.  The default is 0.
28	* vccp_limit_type: integer array (2)
29	  Configures in7 and in8 limit type, where 0 means absolute and non-zero
30	  means relative.  "Relative" here refers to "Dynamic Vccp Monitoring using
31	  VID" from the datasheet.  It greatly simplifies the interface to allow
32	  only one set of limits (absolute or relative) to be in operation at a
33	  time (even though the hardware is capable of enabling both).  There's
34	  not a compelling use case for enabling both at once, anyway.  The default
35	  is "0,0".
36	* vid_agtl: integer
37	  A "0" configures the VID pins for V(ih) = 2.1V min, V(il) = 0.8V max.
38	  A "1" configures the VID pins for V(ih) = 0.8V min, V(il) = 0.4V max.
39	  (The latter setting is referred to as AGTL+ Compatible in the datasheet.)
40	  I.e. this parameter controls the VID pin input thresholds; if your VID
41	  inputs are not working, try changing this.  The default value is "0".
42	
43	
44	Hardware Description
45	--------------------
46	
47	(from the datasheet)
48	
49	The LM93 hardware monitor has a two wire digital interface compatible with
50	SMBus 2.0. Using an 8-bit ADC, the LM93 measures the temperature of two remote
51	diode connected transistors as well as its own die and 16 power supply
52	voltages. To set fan speed, the LM93 has two PWM outputs that are each
53	controlled by up to four temperature zones. The fancontrol algorithm is lookup
54	table based. The LM93 includes a digital filter that can be invoked to smooth
55	temperature readings for better control of fan speed. The LM93 has four
56	tachometer inputs to measure fan speed. Limit and status registers for all
57	measured values are included. The LM93 builds upon the functionality of
58	previous motherboard management ASICs and uses some of the LM85's features
59	(i.e. smart tachometer mode). It also adds measurement and control support
60	for dynamic Vccp monitoring and PROCHOT. It is designed to monitor a dual
61	processor Xeon class motherboard with a minimum of external components.
62	
63	LM94 is also supported in LM93 compatible mode. Extra sensors and features of
64	LM94 are not supported.
65	
66	
67	User Interface
68	--------------
69	
70	#PROCHOT:
71	
72	The LM93 can monitor two #PROCHOT signals.  The results are found in the
73	sysfs files prochot1, prochot2, prochot1_avg, prochot2_avg, prochot1_max,
74	and prochot2_max.  prochot1_max and prochot2_max contain the user limits
75	for #PROCHOT1 and #PROCHOT2, respectively.  prochot1 and prochot2 contain
76	the current readings for the most recent complete time interval.  The
77	value of prochot1_avg and prochot2_avg is something like a 2 period
78	exponential moving average (but not quite - check the datasheet). Note
79	that this third value is calculated by the chip itself.  All values range
80	from 0-255 where 0 indicates no throttling, and 255 indicates > 99.6%.
81	
82	The monitoring intervals for the two #PROCHOT signals is also configurable.
83	These intervals can be found in the sysfs files prochot1_interval and
84	prochot2_interval.  The values in these files specify the intervals for
85	#P1_PROCHOT and #P2_PROCHOT, respectively.  Selecting a value not in this
86	list will cause the driver to use the next largest interval.  The available
87	intervals are (in seconds):
88	
89	#PROCHOT intervals: 0.73, 1.46, 2.9, 5.8, 11.7, 23.3, 46.6, 93.2, 186, 372
90	
91	It is possible to configure the LM93 to logically short the two #PROCHOT
92	signals.  I.e. when #P1_PROCHOT is asserted, the LM93 will automatically
93	assert #P2_PROCHOT, and vice-versa.  This mode is enabled by writing a
94	non-zero integer to the sysfs file prochot_short.
95	
96	The LM93 can also override the #PROCHOT pins by driving a PWM signal onto
97	one or both of them.  When overridden, the signal has a period of 3.56 ms,
98	a minimum pulse width of 5 clocks (at 22.5kHz => 6.25% duty cycle), and
99	a maximum pulse width of 80 clocks (at 22.5kHz => 99.88% duty cycle).
100	
101	The sysfs files prochot1_override and prochot2_override contain boolean
102	integers which enable or disable the override function for #P1_PROCHOT and
103	#P2_PROCHOT, respectively.  The sysfs file prochot_override_duty_cycle
104	contains a value controlling the duty cycle for the PWM signal used when
105	the override function is enabled.  This value ranges from 0 to 15, with 0
106	indicating minimum duty cycle and 15 indicating maximum.
107	
108	#VRD_HOT:
109	
110	The LM93 can monitor two #VRD_HOT signals. The results are found in the
111	sysfs files vrdhot1 and vrdhot2. There is one value per file: a boolean for
112	which 1 indicates #VRD_HOT is asserted and 0 indicates it is negated. These
113	files are read-only.
114	
115	Smart Tach Mode:
116	
117	(from the datasheet)
118	
119		If a fan is driven using a low-side drive PWM, the tachometer
120		output of the fan is corrupted. The LM93 includes smart tachometer
121		circuitry that allows an accurate tachometer reading to be
122		achieved despite the signal corruption.  In smart tach mode all
123		four signals are measured within 4 seconds.
124	
125	Smart tach mode is enabled by the driver by writing 1 or 2 (associating the
126	the fan tachometer with a pwm) to the sysfs file fan<n>_smart_tach.  A zero
127	will disable the function for that fan.  Note that Smart tach mode cannot be
128	enabled if the PWM output frequency is 22500 Hz (see below).
129	
130	Manual PWM:
131	
132	The LM93 has a fixed or override mode for the two PWM outputs (although, there
133	are still some conditions that will override even this mode - see section
134	15.10.6 of the datasheet for details.)  The sysfs files pwm1_override
135	and pwm2_override are used to enable this mode; each is a boolean integer
136	where 0 disables and 1 enables the manual control mode.  The sysfs files pwm1
137	and pwm2 are used to set the manual duty cycle; each is an integer (0-255)
138	where 0 is 0% duty cycle, and 255 is 100%.  Note that the duty cycle values
139	are constrained by the hardware. Selecting a value which is not available
140	will cause the driver to use the next largest value.  Also note: when manual
141	PWM mode is disabled, the value of pwm1 and pwm2 indicates the current duty
142	cycle chosen by the h/w.
143	
144	PWM Output Frequency:
145	
146	The LM93 supports several different frequencies for the PWM output channels.
147	The sysfs files pwm1_freq and pwm2_freq are used to select the frequency. The
148	frequency values are constrained by the hardware.  Selecting a value which is
149	not available will cause the driver to use the next largest value.  Also note
150	that this parameter has implications for the Smart Tach Mode (see above).
151	
152	PWM Output Frequencies (in Hz): 12, 36, 48, 60, 72, 84, 96, 22500 (default)
153	
154	Automatic PWM:
155	
156	The LM93 is capable of complex automatic fan control, with many different
157	points of configuration.  To start, each PWM output can be bound to any
158	combination of eight control sources.  The final PWM is the largest of all
159	individual control sources to which the PWM output is bound.
160	
161	The eight control sources are: temp1-temp4 (aka "zones" in the datasheet),
162	#PROCHOT 1 & 2, and #VRDHOT 1 & 2.  The bindings are expressed as a bitmask
163	in the sysfs files pwm<n>_auto_channels, where a "1" enables the binding, and
164	a "0" disables it. The h/w default is 0x0f (all temperatures bound).
165	
166		0x01 - Temp 1
167		0x02 - Temp 2
168		0x04 - Temp 3
169		0x08 - Temp 4
170		0x10 - #PROCHOT 1
171		0x20 - #PROCHOT 2
172		0x40 - #VRDHOT 1
173		0x80 - #VRDHOT 2
174	
175	The function y = f(x) takes a source temperature x to a PWM output y.  This
176	function of the LM93 is derived from a base temperature and a table of 12
177	temperature offsets.  The base temperature is expressed in degrees C in the
178	sysfs files temp<n>_auto_base.  The offsets are expressed in cumulative
179	degrees C, with the value of offset <i> for temperature value <n> being
180	contained in the file temp<n>_auto_offset<i>.  E.g. if the base temperature
181	is 40C:
182	
183	     offset #	temp<n>_auto_offset<i>	range		pwm
184		 1		0		-		 25.00%
185		 2		0		-		 28.57%
186		 3		1		40C - 41C	 32.14%
187		 4		1		41C - 42C	 35.71%
188		 5		2		42C - 44C	 39.29%
189		 6		2		44C - 46C	 42.86%
190		 7		2		48C - 50C	 46.43%
191		 8		2		50C - 52C	 50.00%
192		 9		2		52C - 54C	 53.57%
193		10		2		54C - 56C	 57.14%
194		11		2		56C - 58C	 71.43%
195		12		2		58C - 60C	 85.71%
196						> 60C		100.00%
197	
198	Valid offsets are in the range 0C <= x <= 7.5C in 0.5C increments.
199	
200	There is an independent base temperature for each temperature channel. Note,
201	however, there are only two tables of offsets: one each for temp[12] and
202	temp[34].  Therefore, any change to e.g. temp1_auto_offset<i> will also
203	affect temp2_auto_offset<i>.
204	
205	The LM93 can also apply hysteresis to the offset table, to prevent unwanted
206	oscillation between two steps in the offsets table.  These values are found in
207	the sysfs files temp<n>_auto_offset_hyst.  The value in this file has the
208	same representation as in temp<n>_auto_offset<i>.
209	
210	If a temperature reading falls below the base value for that channel, the LM93
211	will use the minimum PWM value.  These values are found in the sysfs files
212	temp<n>_auto_pwm_min.  Note, there are only two minimums: one each for temp[12]
213	and temp[34].  Therefore, any change to e.g. temp1_auto_pwm_min will also
214	affect temp2_auto_pwm_min.
215	
216	PWM Spin-Up Cycle:
217	
218	A spin-up cycle occurs when a PWM output is commanded from 0% duty cycle to
219	some value > 0%.  The LM93 supports a minimum duty cycle during spin-up.  These
220	values are found in the sysfs files pwm<n>_auto_spinup_min. The value in this
221	file has the same representation as other PWM duty cycle values. The
222	duration of the spin-up cycle is also configurable.  These values are found in
223	the sysfs files pwm<n>_auto_spinup_time. The value in this file is
224	the spin-up time in seconds.  The available spin-up times are constrained by
225	the hardware.  Selecting a value which is not available will cause the driver
226	to use the next largest value.
227	
228	Spin-up Durations: 0 (disabled, h/w default), 0.1, 0.25, 0.4, 0.7, 1.0,
229			   2.0, 4.0
230	
231	#PROCHOT and #VRDHOT PWM Ramping:
232	
233	If the #PROCHOT or #VRDHOT signals are asserted while bound to a PWM output
234	channel, the LM93 will ramp the PWM output up to 100% duty cycle in discrete
235	steps. The duration of each step is configurable. There are two files, with
236	one value each in seconds: pwm_auto_prochot_ramp and pwm_auto_vrdhot_ramp.
237	The available ramp times are constrained by the hardware.  Selecting a value
238	which is not available will cause the driver to use the next largest value.
239	
240	Ramp Times: 0 (disabled, h/w default) to 0.75 in 0.05 second intervals
241	
242	Fan Boost:
243	
244	For each temperature channel, there is a boost temperature: if the channel
245	exceeds this limit, the LM93 will immediately drive both PWM outputs to 100%.
246	This limit is expressed in degrees C in the sysfs files temp<n>_auto_boost.
247	There is also a hysteresis temperature for this function: after the boost
248	limit is reached, the temperature channel must drop below this value before
249	the boost function is disabled.  This temperature is also expressed in degrees
250	C in the sysfs files temp<n>_auto_boost_hyst.
251	
252	GPIO Pins:
253	
254	The LM93 can monitor the logic level of four dedicated GPIO pins as well as the
255	four tach input pins.  GPIO0-GPIO3 correspond to (fan) tach 1-4, respectively.
256	All eight GPIOs are read by reading the bitmask in the sysfs file gpio.  The
257	LSB is GPIO0, and the MSB is GPIO7.
258	
259	
260	LM93 Unique sysfs Files
261	-----------------------
262	
263		file			description
264		-------------------------------------------------------------
265	
266		prochot<n>		current #PROCHOT %
267	
268		prochot<n>_avg		moving average #PROCHOT %
269	
270		prochot<n>_max		limit #PROCHOT %
271	
272		prochot_short		enable or disable logical #PROCHOT pin short
273	
274		prochot<n>_override	force #PROCHOT assertion as PWM
275	
276		prochot_override_duty_cycle
277					duty cycle for the PWM signal used when
278					#PROCHOT is overridden
279	
280		prochot<n>_interval	#PROCHOT PWM sampling interval
281	
282		vrdhot<n>		0 means negated, 1 means asserted
283	
284		fan<n>_smart_tach	enable or disable smart tach mode
285	
286		pwm<n>_auto_channels	select control sources for PWM outputs
287	
288		pwm<n>_auto_spinup_min	minimum duty cycle during spin-up
289	
290		pwm<n>_auto_spinup_time	duration of spin-up
291	
292		pwm_auto_prochot_ramp	ramp time per step when #PROCHOT asserted
293	
294		pwm_auto_vrdhot_ramp	ramp time per step when #VRDHOT asserted
295	
296		temp<n>_auto_base	temperature channel base
297	
298		temp<n>_auto_offset[1-12]
299					temperature channel offsets
300	
301		temp<n>_auto_offset_hyst
302					temperature channel offset hysteresis
303	
304		temp<n>_auto_boost	temperature channel boost (PWMs to 100%) limit
305	
306		temp<n>_auto_boost_hyst	temperature channel boost hysteresis
307	
308		gpio			input state of 8 GPIO pins; read-only
Hide Line Numbers
About Kernel Documentation Linux Kernel Contact Linux Resources Linux Blog

Information is copyright its respective author. All material is available from the Linux Kernel Source distributed under a GPL License. This page is provided as a free service by mjmwired.net.