Message-Id: <1459714006-5826-1-git-send-email-srinivas.pandruvada@linux.intel.com>
Date:	Sun,  3 Apr 2016 13:06:46 -0700
From:	Srinivas Pandruvada <srinivas.pandruvada@...ux.intel.com>
To:	rjw@...ysocki.net
Cc:	linux-pm@...r.kernel.org, linux-kernel@...r.kernel.org,
	Srinivas Pandruvada <srinivas.pandruvada@...ux.intel.com>
Subject: [PATCH] cpufreq: intel_pstate: Documenation for structures

No code change. Only added kernel doc style comments for structures.

Signed-off-by: Srinivas Pandruvada <srinivas.pandruvada@...ux.intel.com>
---
 drivers/cpufreq/intel_pstate.c | 135 +++++++++++++++++++++++++++++++++++++++++
 1 file changed, 135 insertions(+)

diff --git a/drivers/cpufreq/intel_pstate.c b/drivers/cpufreq/intel_pstate.c
index 776cea7..f7d4047 100644
--- a/drivers/cpufreq/intel_pstate.c
+++ b/drivers/cpufreq/intel_pstate.c
@@ -64,6 +64,25 @@ static inline int ceiling_fp(int32_t x)
 	return ret;
 }
 
+/**
+ * struct sample -	Store performance sample
+ * @core_pct_busy:	Ratio of APERF/MPERF in percent, which is actual
+ *			performance during last sample period
+ * @busy_scaled:	Scaled busy value which is used to calculate next
+ *			P state. This can be different than core_pct_busy
+ *			to account for cpu idle period
+ * @aperf:		Difference of actual performance frequency clock count
+ *			read from APERF MSR between last and current sample
+ * @mperf:		Difference of maximum performance frequency clock count
+ *			read from MPERF MSR between last and current sample
+ * @tsc:		Difference of time stamp counter between last and
+ *			current sample
+ * @freq:		Effective frequency calculated from APERF/MPERF
+ * @time:		Current time from scheduler
+ *
+ * This structure is used in the cpudata structure to store performance sample
+ * data for choosing next P State.
+ */
 struct sample {
 	int32_t core_pct_busy;
 	int32_t busy_scaled;
@@ -74,6 +93,20 @@ struct sample {
 	u64 time;
 };
 
+/**
+ * struct pstate_data - Store P state data
+ * @current_pstate:	Current requested P state
+ * @min_pstate:		Min P state possible for this platform
+ * @max_pstate:		Max P state possible for this platform
+ * @max_pstate_physical:This is physical Max P state for a processor
+ *			This can be higher than the max_pstate which can
+ *			be limited by platform thermal design power limits
+ * @scaling:		Scaling factor to  convert frequency to cpufreq
+ *			frequency units
+ * @turbo_pstate:	Max Turbo P state possible for this platform
+ *
+ * Stores the per cpu model P state limits and current P state.
+ */
 struct pstate_data {
 	int	current_pstate;
 	int	min_pstate;
@@ -83,6 +116,19 @@ struct pstate_data {
 	int	turbo_pstate;
 };
 
+/**
+ * struct vid_data -	Stores voltage information data
+ * @min:		VID data for this platform corresponding to
+ *			the lowest P state
+ * @max:		VID data corresponding to the highest P State.
+ * @turbo:		VID data for turbo P state
+ * @ratio:		Ratio of (vid max - vid min) /
+ *			(max P state - Min P State)
+ *
+ * Stores the voltage data for DVFS (Dynamic Voltage and Frequency Scaling)
+ * This data is used in Atom platforms, where in addition to target P state,
+ * the voltage data needs to be specified to select next P State.
+ */
 struct vid_data {
 	int min;
 	int max;
@@ -90,6 +136,18 @@ struct vid_data {
 	int32_t ratio;
 };
 
+/**
+ * struct _pid -	Stores PID data
+ * @setpoint:		Target set point for busyness or performance
+ * @integral:		Storage for accumulated error values
+ * @p_gain:		PID proportional gain
+ * @i_gain:		PID integral gain
+ * @d_gain:		PID derivative gain
+ * @deadband:		PID deadband
+ * @last_err:		Last error storage for integral part of PID calculation
+ *
+ * Stores PID coefficients and last error for PID controller.
+ */
 struct _pid {
 	int setpoint;
 	int32_t integral;
@@ -100,6 +158,23 @@ struct _pid {
 	int32_t last_err;
 };
 
+/**
+ * struct cpudata -	Per CPU instance data storage
+ * @cpu:		CPU number for this instance data
+ * @update_util:	CPUFreq utility callback information
+ * @pstate:		Stores P state limits for this CPU
+ * @vid:		Stores VID limits for this CPU
+ * @pid:		Stores PID parameters for this CPU
+ * @last_sample_time:	Last Sample time
+ * @prev_aperf:		Last APERF value read from APERF MSR
+ * @prev_mperf:		Last MPERF value read from MPERF MSR
+ * @prev_tsc:		Last timestamp counter (TSC) value
+ * @prev_cummulative_iowait: IO Wait time difference from last and
+ *			current sample
+ * @sample:		Storage for storing last Sample data
+ *
+ * This structure stores per CPU instance data for all CPUs.
+ */
 struct cpudata {
 	int cpu;
 
@@ -118,6 +193,19 @@ struct cpudata {
 };
 
 static struct cpudata **all_cpu_data;
+
+/**
+ * struct pid_adjust_policy - Stores static PID configuration data
+ * @sample_rate_ms:	PID calculation sample rate in ms
+ * @sample_rate_ns:	Sample rate calculation in ns
+ * @deadband:		PID deadband
+ * @setpoint:		PID Setpoint
+ * @p_gain_pct:		PID proportional gain
+ * @i_gain_pct:		PID integral gain
+ * @d_gain_pct:		PID derivative gain
+ *
+ * Stores per CPU model static PID configuration data.
+ */
 struct pstate_adjust_policy {
 	int sample_rate_ms;
 	s64 sample_rate_ns;
@@ -128,6 +216,20 @@ struct pstate_adjust_policy {
 	int i_gain_pct;
 };
 
+/**
+ * struct pstate_funcs - Per CPU model specific callbacks
+ * @get_max:		Callback to get maximum non turbo effective P state
+ * @get_max_physical:	Callback to get maximum non turbo physical P state
+ * @get_min:		Callback to get minimum P state
+ * @get_turbo:		Callback to get turbo P state
+ * @get_scaling:	Callback to get frequency scaling factor
+ * @get_val:		Callback to convert P state to actual MSR write value
+ * @get_vid:		Callback to get VID data for Atom platforms
+ * @get_target_pstate:	Callback to a function to calculate next P state to use
+ *
+ * Core and Atom CPU models have different way to get P State limits. This
+ * structure is used to store those callbacks.
+ */
 struct pstate_funcs {
 	int (*get_max)(void);
 	int (*get_max_physical)(void);
@@ -139,6 +241,11 @@ struct pstate_funcs {
 	int32_t (*get_target_pstate)(struct cpudata *);
 };
 
+/**
+ * struct cpu_defaults- Per CPU model default config data
+ * @pid_policy:	PID config data
+ * @funcs:		Callback function data
+ */
 struct cpu_defaults {
 	struct pstate_adjust_policy pid_policy;
 	struct pstate_funcs funcs;
@@ -151,6 +258,34 @@ static struct pstate_adjust_policy pid_params;
 static struct pstate_funcs pstate_funcs;
 static int hwp_active;
 
+
+/**
+ * struct perf_limits - Store user and policy limits
+ * @no_turbo:		User requested turbo state from intel_pstate sysfs
+ * @turbo_disabled:	Platform turbo status either from msr
+ *			MSR_IA32_MISC_ENABLE or when maximum available pstate
+ *			matches the maximum turbo pstate
+ * @max_perf_pct:	Effective maximum performance limit in percentage, this
+ *			is minimum of either limits enforced by cpufreq policy
+ *			or limits from user set limits via intel_pstate sysfs
+ * @min_perf_pct:	Effective minimum performance limit in percentage, this
+ *			is maximum of either limits enforced by cpufreq policy
+ *			or limits from user set limits via intel_pstate sysfs
+ * @max_perf:		This is a scaled value between 0 to 255 for max_perf_pct
+ *			This value is used to limit max pstate
+ * @min_perf:		This is a scaled value between 0 to 255 for min_perf_pct
+ *			This value is used to limit min pstate
+ * @max_policy_pct:	The maximum performance in percentage enforced by
+ *			cpufreq setpolicy interface
+ * @max_sysfs_pct:	The maximum performance in percentage enforced by
+ *			intel pstate sysfs interface
+ * @min_policy_pct:	The minimum performance in percentage enforced by
+ *			cpufreq setpolicy interface
+ * @min_sysfs_pct:	The minimum performance in percentage enforced by
+ *			intel pstate sysfs interface
+ *
+ * Storage for user and policy defined limits.
+ */
 struct perf_limits {
 	int no_turbo;
 	int turbo_disabled;
-- 
2.5.0

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