Lines Matching +full:max +full:- +full:frequency
1 .. SPDX-License-Identifier: GPL-2.0
10 - Dominik Brodowski <linux@brodo.de>
11 - Rafael J. Wysocki <rafael.j.wysocki@intel.com>
12 - Viresh Kumar <viresh.kumar@linaro.org>
18 1.2 Per-CPU Initialization
24 2. Frequency Table Helpers
31 So, you just got a brand-new CPU / chipset with datasheets and want to
37 ------------------
46 .name - The name of this driver.
48 .init - A pointer to the per-policy initialization function.
50 .verify - A pointer to a "verification" function.
52 .setpolicy _or_ .fast_switch _or_ .target _or_ .target_index - See
57 .flags - Hints for the cpufreq core.
59 .driver_data - cpufreq driver specific data.
61 .get_intermediate and target_intermediate - Used to switch to stable
62 frequency while changing CPU frequency.
64 .get - Returns current frequency of the CPU.
66 .bios_limit - Returns HW/BIOS max frequency limitations for the CPU.
68 .exit - A pointer to a per-policy cleanup function called during
71 .suspend - A pointer to a per-policy suspend function which is called
75 .resume - A pointer to a per-policy resume function which is called
78 .attr - A pointer to a NULL-terminated list of "struct freq_attr" which
81 .boost_enabled - If set, boost frequencies are enabled.
83 .set_boost - A pointer to a per-policy function to enable/disable boost
87 1.2 Per-CPU Initialization
88 --------------------------
91 cpufreq driver registers itself, the per-policy initialization function
101 +-----------------------------------+--------------------------------------+
102 |policy->cpuinfo.min_freq _and_ | |
103 |policy->cpuinfo.max_freq | the minimum and maximum frequency |
106 +-----------------------------------+--------------------------------------+
107 |policy->cpuinfo.transition_latency | the time it takes on this CPU to |
111 +-----------------------------------+--------------------------------------+
112 |policy->cur | The current operating frequency of |
114 +-----------------------------------+--------------------------------------+
115 |policy->min, | |
116 |policy->max, | |
117 |policy->policy and, if necessary, | |
118 |policy->governor | must contain the "default policy" for|
124 +-----------------------------------+--------------------------------------+
125 |policy->cpus | Update this with the masks of the |
129 +-----------------------------------+--------------------------------------+
131 For setting some of these values (cpuinfo.min[max]_freq, policy->min[max]), the
132 frequency table helpers might be helpful. See the section 2 for more information
137 ----------
140 "policy,governor,min,max") shall be set, this policy must be validated
144 See section 2 for details on frequency table helpers.
146 You need to make sure that at least one valid frequency (or operating
147 range) is within policy->min and policy->max. If necessary, increase
148 policy->max first, and only if this is no solution, decrease policy->min.
152 -------------------------------------------------------
154 Most cpufreq drivers or even most cpu frequency scaling algorithms
155 only allow the CPU frequency to be set to predefined fixed values. For
156 these, you use the ->target(), ->target_index() or ->fast_switch()
159 Some cpufreq capable processors switch the frequency between certain
160 limits on their own. These shall use the ->setpolicy() callback.
164 ------------------------
167 and ``unsigned int`` index (into the exposed frequency table).
169 The CPUfreq driver must set the new frequency when called here. The
170 actual frequency must be determined by freq_table[index].frequency.
172 It should always restore to earlier frequency (i.e. policy->restore_freq) in
173 case of errors, even if we switched to intermediate frequency earlier.
176 ----------
180 The CPUfreq driver must set the new frequency when called here. The
181 actual frequency must be determined using the following rules:
183 - keep close to "target_freq"
184 - policy->min <= new_freq <= policy->max (THIS MUST BE VALID!!!)
185 - if relation==CPUFREQ_REL_L, try to select a new_freq higher than or equal
187 - if relation==CPUFREQ_REL_H, try to select a new_freq lower than or equal
190 Here again the frequency table helper might assist you - see section 2
194 ----------------
196 This function is used for frequency switching from scheduler's context.
206 -------------
209 argument. You need to set the lower limit of the in-processor or
210 in-chipset dynamic frequency switching to policy->min, the upper limit
211 to policy->max, and -if supported- select a performance-oriented
212 setting when policy->policy is CPUFREQ_POLICY_PERFORMANCE, and a
213 powersaving-oriented setting when CPUFREQ_POLICY_POWERSAVE. Also check
217 --------------------------------------------
221 get_intermediate should return a stable intermediate frequency platform wants to
222 switch to, and target_intermediate() should set CPU to that frequency, before
223 jumping to the frequency corresponding to 'index'. Core will take care of
228 to intermediate frequency for some target frequency. In that case core will
229 directly call ->target_index().
231 NOTE: ->target_index() should restore to policy->restore_freq in case of
235 2. Frequency Table Helpers
239 frequencies, a "frequency table" with some functions might assist in
240 some work of the processor driver. Such a "frequency table" consists of
242 values in "driver_data", the corresponding frequency in "frequency" and
244 cpufreq_frequency_table entry with frequency set to CPUFREQ_TABLE_END.
245 And if you want to skip one entry in the table, set the frequency to
251 valid pointer in its policy->freq_table field.
254 frequency is within policy->min and policy->max, and all other criteria
255 are met. This is helpful for the ->verify call.
257 cpufreq_frequency_table_target() is the corresponding frequency table
258 helper for the ->target stage. Just pass the values to this function,
259 and this function returns the of the frequency table entry which
260 contains the frequency the CPU shall be set to.
264 cpufreq_for_each_entry(pos, table) - iterates over all entries of frequency
267 cpufreq_for_each_valid_entry(pos, table) - iterates over all entries,
269 Use arguments "pos" - a ``cpufreq_frequency_table *`` as a loop cursor and
270 "table" - the ``cpufreq_frequency_table *`` you want to iterate over.
278 pos->frequency = ...