mmc: core: devfreq: migrate to devfreq based clock scaling

This change adds the use of devfreq to MMC.
Both eMMC and SD card will use it.
For some workloads, such as video playback, it isn't
necessary for these cards to run at high speed.
Running at lower frequency, for example 52MHz, in such
cases can still meet the deadlines for data transfers.
Scaling down the clock frequency dynamically has power
savings not only because the bus is running at lower frequency
but also has an advantage of scaling down the system core
voltage, if supported.
Provide an ondemand clock scaling support similar to the
cpufreq ondemand governor having two thresholds,
up_threshold and down_threshold to decide whether to
increase the frequency or scale it down respectively.
The sampling interval is in the order of milliseconds.
If sampling interval is too low, frequent switching of
frequencies can lead to high power consumption and if
sampling interval is too high, the clock scaling logic
would take long time to realize that the underlying
hardware (controller and card) is busy and scale up
the clocks.

Change-Id: I58ddbd93648ded82b304411956e035fb353cd97e
Signed-off-by: Talel Shenhar <tatias@codeaurora.org>
[subhashj@codeaurora.org: fixed trivial merge conflicts & compilation
errors]
Signed-off-by: Subhash Jadavani <subhashj@codeaurora.org>

2 files changed, 53 insertions, 16 deletions

diff --git a/include/linux/mmc/card.h b/include/linux/mmc/card.h
index 59ef4e717beb..ae943ccb331e 100644
--- a/include/linux/mmc/card.h
+++ b/include/linux/mmc/card.h
@@ -275,6 +275,10 @@ struct mmc_card {
 	struct mmc_host		*host;		/* the host this device belongs to */
 	struct device		dev;		/* the device */
 	u32			ocr;		/* the current OCR setting */
+	unsigned long		clk_scaling_lowest;	/* lowest scaleable
+							 * frequency */
+	unsigned long		clk_scaling_highest;	/* highest scaleable
+							 * frequency */
 	unsigned int		rca;		/* relative card address of device */
 	unsigned int		type;		/* card type */
 #define MMC_TYPE_MMC		0		/* MMC card */
diff --git a/include/linux/mmc/host.h b/include/linux/mmc/host.h
index 2ba8ba249e00..5afbac264ddd 100644
--- a/include/linux/mmc/host.h
+++ b/include/linux/mmc/host.h
@@ -15,6 +15,7 @@
 #include <linux/timer.h>
 #include <linux/sched.h>
 #include <linux/device.h>
+#include <linux/devfreq.h>
 #include <linux/fault-inject.h>
 
 #include <linux/mmc/core.h>
@@ -224,9 +225,57 @@ enum dev_state {
 	DEV_RESUMED,
 };
 
+/**
+ * struct mmc_devfeq_clk_scaling - main context for MMC clock scaling logic
+ *
+ * @lock: spinlock to protect statistics
+ * @devfreq: struct that represent mmc-host as a client for devfreq
+ * @devfreq_profile: MMC device profile, mostly polling interval and callbacks
+ * @ondemand_gov_data: struct supplied to ondemmand governor (thresholds)
+ * @state: load state, can be HIGH or LOW. used to notify mmc_host_ops callback
+ * @start_busy: timestamped armed once a data request is started
+ * @measure_interval_start: timestamped armed once a measure interval started
+ * @devfreq_abort: flag to sync between different contexts relevant to devfreq
+ * @skip_clk_scale_freq_update: flag that enable/disable frequency change
+ * @freq_table_sz: table size of frequencies supplied to devfreq
+ * @freq_table: frequencies table supplied to devfreq
+ * @curr_freq: current frequency
+ * @polling_delay_ms: polling interval for status collection used by devfreq
+ * @upthreshold: up-threshold supplied to ondemand governor
+ * @downthreshold: down-threshold supplied to ondemand governor
+ * @need_freq_change: flag indicating if a frequency change is required
+ * @clk_scaling_in_progress: flag indicating if there's ongoing frequency change
+ * @is_busy_started: flag indicating if a request is handled by the HW
+ * @enable: flag indicating if the clock scaling logic is enabled for this host
+ */
+struct mmc_devfeq_clk_scaling {
+	spinlock_t	lock;
+	struct		devfreq *devfreq;
+	struct		devfreq_dev_profile devfreq_profile;
+	struct		devfreq_simple_ondemand_data ondemand_gov_data;
+	enum mmc_load	state;
+	ktime_t		start_busy;
+	ktime_t		measure_interval_start;
+	atomic_t	devfreq_abort;
+	bool		skip_clk_scale_freq_update;
+	int		freq_table_sz;
+	u32		*freq_table;
+	unsigned long	total_busy_time_us;
+	unsigned long	target_freq;
+	unsigned long	curr_freq;
+	unsigned long	polling_delay_ms;
+	unsigned int	upthreshold;
+	unsigned int	downthreshold;
+	bool		need_freq_change;
+	bool		clk_scaling_in_progress;
+	bool		is_busy_started;
+	bool		enable;
+};
+
 struct mmc_host {
 	struct device		*parent;
 	struct device		class_dev;
+	struct mmc_devfeq_clk_scaling	clk_scaling;
 	int			index;
 	const struct mmc_host_ops *ops;
 	struct mmc_pwrseq	*pwrseq;
@@ -441,22 +490,6 @@ struct mmc_host {
 	} perf;
 	bool perf_enable;
 #endif
-	struct {
-		unsigned long	busy_time_us;
-		unsigned long	window_time;
-		unsigned long	curr_freq;
-		unsigned long	polling_delay_ms;
-		unsigned int	up_threshold;
-		unsigned int	down_threshold;
-		ktime_t		start_busy;
-		bool		enable;
-		bool		initialized;
-		bool		in_progress;
-		/* freq. transitions are not allowed in invalid state */
-		bool		invalid_state;
-		struct delayed_work work;
-		enum mmc_load	state;
-	} clk_scaling;
 	enum dev_state dev_status;
 	bool			wakeup_on_idle;
 	unsigned long		private[0] ____cacheline_aligned;