Medfield_Current_Monitoring_Driver

This is the Intel Medfield Current Monitoring Driver patch.
The platform specific data required by the driver are provided by
adding necessary code in arch/x86/platform/mrst/mrst.c

This driver monitors the platform current usage and handles interrupts
when the configured current thresholds are crossed.
A detailed documentation for this, has been added in
Documentation/hwmon/current_monitor.

Signed-off-by: Durgadoss R <durgadoss.r@intel.com>
Signed-off-by: Alan Cox <alan@linux.intel.com>

1 files changed, 86 insertions, 0 deletions

diff --git a/Documentation/hwmon/intel_over_current_detector b/Documentation/hwmon/intel_over_current_detector
new file mode 100644
index 00000000000..d9483b0b6af
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+Kernel driver over current detection driver
+===========================================
+
+Supported systems:
+  * Intel Medfield Platform
+
+Author: Durgadoss R
+
+Description
+-----------
+
+This driver monitors the current drawn by the platform, and detects the
+peak current conditions. When the current drawn is more than the
+configured limit for a period of time (which is specified by a timer), an
+interrupt is generated. The current limit and the timer value can be
+configured at run time.
+
+The current thresholds aka BATTCURRENTLIMITS(BC) are of two types:
+	1.warning threshold(BC1)
+		at which the system should take actions to bring the
+		current consumption down.
+	2.shutdown threshold(BC2)
+		at which the hardware does a COLDOFF.
+
+The timer thresholds are of three types:
+	1.warning threshold(T1)
+		This corresponds to the first flag for time that the battery
+		current has been above BC1. An interrupt is generated to allow
+		software to correct the situation based on use-case.
+	2.hardware action threshold(T2)
+		This corresponds to the second flag for time that the battery
+		current has been above BC1. It signifies that the system
+		should control high current subsystems through hardware.
+		Besides a general interrupt, audio_volume_crush, vibra_disable
+		signals are sent.
+	3.shutdown threshold(T3)
+		This final flag signifies that when the system current exceeds
+		the threshold for more than T3, system should shutdown.
+
+Following table summarizes the exported sysfs files:
+
+bcu_status(RW)	     -  To enable/disable burst control unit.
+			0 - enables bcu, 1 - disables bcu.
+accumulation_time(RW)-  Time since last clearing/overflow of warning_count
+			in milli seconds. Writing 0 resets the acc_time and
+			also clears both the warning counters.
+warning_count(RO)    -  Two space seperated values that indicate the number
+			of times the current thresholds have been crossed.
+action_mask(RW)	     -  A hex value to enable/disable specific
+			actions taken when current violation happens.
+			bits [b4 b3 b2 b1 b0] control [a4 a3 a2 a1 a0] actions
+			respectively. a4 - camera output, a3 - sys burst,
+			a2 - SOC burst enable, a1 - vibra, a0 - audio output.
+			bits [b7 b6 b5] - Reserved.
+			Default value:08 (sys burst output is enabled).
+action_status(RO)    -  A hex value showing the status of actions taken
+			since the __last__ interrupt.
+			b7 - T3 violation
+			b6 - T2 violation
+			b5 - T1 violation
+			b4 - camera action taken status
+			b3 - sys burst disable action taken status
+			b2 - SOC burst disable action taken status
+			b1 - vibra disable
+			b0 - audio volume crush
+			A '1' in a bit position indicates that particular
+			action has been taken.
+current_warning(RW)  -  This gives the current(in mA) at which a warning is
+			generated. Range: 1400 to 4800. Default:3000
+current_shutdown(RW) -  This gives the current(in mA) at which system shutdown
+			is initiated. Range:1800 to 5800. Default:3800
+timer_warning(RW)    -  Time above current_warning limit at which interrupts
+			are trigerred(so that software can bring the current
+			consumption down). Values are in micro seconds.
+			Range:200 to 7700 in steps of 500
+timer_hw_action(RW)  -  Time above current_warning limit at which the system
+			is trigerred into hardware control to bring down the
+			current consumption. Values are in micro seconds.
+			Range:200 to 7700 in steps of 500
+timer_shutdown(RW)   -  Time above current_warning limit at which a hardware
+			shutdown event is trigerred. The timer values are in
+			micro seconds.
+			Range:1000 to 15000 in steps of 1000
+For all timer interfaces, tolerance shall be 5% maximum.
+All timers start running concurrently once current_warning/current_shutdown
+is crossed.