Documentation/power/opp.rst

5 (C) 2009-2010 Nishanth Menon <nm@ti.com>, Texas Instruments Incorporated
20 -------------------------------------------------
22 Complex SoCs of today consists of a multiple sub-modules working in conjunction.
25 facilitate this, sub-modules in a SoC are grouped into domains, allowing some
41 - {300000000, 1000000}
42 - {800000000, 1200000}
43 - {1000000000, 1300000}
46 ----------------------------------------
49 information. The library is located in drivers/opp/ directory and the header
50 is located in include/linux/pm_opp.h. OPP library can be enabled by enabling
57  (users)	-> registers a set of default OPPs		-> (library)
58  SoC framework	-> modifies on required cases certain OPPs	-> OPP layer
59 		-> queries to search/retrieve information	->
74 operations until that OPP could be re-enabled if possible.
96 optimally- typical numbers range to be less than 5. The list generated by
186 	Example 2: A simplified implementation of a SoC cpufreq_driver->target::
293 			 return -EINVAL;
295 			 return -EINVAL;
301 	Example: Lets say a co-processor in the SoC needs to know the available
329    |- device 1
330    |	|- opp 1 (availability, freq, voltage)
331    |	|- opp 2 ..
333    |	`- opp n ..
334    |- device 2
336    `- device m
366               +-----+        /- dev_pm_opp_enable
367   dev_pm_opp_add --> | opp | <-------
368     |         +-----+        \- dev_pm_opp_disable
369     \-------> domain_info(device)
372                /-- dev_pm_opp_find_freq_ceil  ---\   +-----+
373   domain_info<---- dev_pm_opp_find_freq_exact -----> | opp |
374                \-- dev_pm_opp_find_freq_floor ---/   +-----+
377   +-----+     /- dev_pm_opp_get_voltage
378   | opp | <---
379   +-----+     \- dev_pm_opp_get_freq
381   domain_info <- dev_pm_opp_get_opp_count