drivers/misc/airbrush/DEBUG_DOCUMENTATION

Documentation on how to use debugfs/sysfs entries for airbush:

1. State Manager (/sys/kernel/debug/airbrush/airbrush_sm)
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The entry of utmost importance is the read-write file:

"chip_state"
	Reading: Exports the information about the current state of the overall
		chip.
	Writing: On writing another chip state, it changes the overall chip-
		-state to that state.

Other than that, there are directories for each block (IPU, TPU, DRAM, MIF,
FSYS, AON) each of which contains the following READ-ONLY entries which exports
information about the respective block:

"state_id"
	current block-state-id

"state_name"
	name of the curent state

"substate_name"
	name of the current substate.

"rail_en"
	current status of the voltage_rail

"logic_voltage"
	current logic voltage

"clk_status"
	current clock tree gating status

"clk_frequency"
	current clock_frequency.
	(This value is only superficial, for actual value maintained by software
	see Clock Section below)

"num_powered_cores"
	current number of powered_cores (Applicable in case of IPU only)

"num_computing_cores"
	current number of computing_cores (Applicable in case of IPU only)

"num_powered_tiles"
	current number of powered_tiles (Applicable in case of TPU only)

"data_rate"
	current data_rate (Applicable in case of DRAM and FSYS)

2. Clocks (/sys/kernel/debug/clk/)
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After the first write to /sys/kernel/debug/airbrush/airbrush_sm/chip_state,
various clocks will be registered.
Once registered we can see various debugfs entries inside /sys/kernel/debug/clk/

"clk_summary" is one such read-only debugfs entry provided by CCF
	Reading it exports vaious information about clock tree in a tabular
	format.

Each clock creates it's own subdirectory by the name of the clock and inside it
one can find many debugfs entries exporting properties of the clock.

"clk_rate"
	Reading: exports the frequency of the clock
	Writing: changes the rate of the clock to the given frequency
		(for PLL clocks or divider clocks)

"clk_parent"
	Reading: exports the name of the parent clock
	Writing: changes the clock parent

"clk_enable_count"
	Reading: exports the enable_count of the clock.
	Writing: Enables/Disables the clock depending on the value written.

"clk_prepare_count"
	Reading: exports the prepare_count of the clock.
	Writing: Prepares/Unprepares the clock depending on the value written.

"clk_flags"
	Reading: exports the value of flags
	Writing: Invalid

"clk_notifier_count", "clk_phase", "clk_accuracy" are not used in case of 
airbrush.

3. DDR
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Debugfs entry for DDR control is /sys/kernel/debug/airbrush/ab_ddr_ctrl

"ab_ddr_ctrl"
	Reading: Invalid
	Writing: 0 to trigger ddr_init()
		 1 to trigger ddr_suspend()
		 3 to trigger ddr_resume()