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exynos_thermal_emulation

exynos_thermal_emulation 2.2 KB
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  1. EXYNOS EMULATION MODE
    2. 

  2. ========================
    3. 

  3. 

  4. Copyright (C) 2012 Samsung Electronics
    5. 

  5. 

  6. Written by Jonghwa Lee <jonghwa3.lee@samsung.com>
    7. 

  7. 

  8. Description
    9. 

  9. -----------
    10. 

  10. 

  11. Exynos 4x12 (4212, 4412) and 5 series provide emulation mode for thermal management unit.
    12. 

  12. Thermal emulation mode supports software debug for TMU's operation. User can set temperature
    13. 

  13. manually with software code and TMU will read current temperature from user value not from
    14. 

  14. sensor's value.
    15. 

  15. 

  16. Enabling CONFIG_THERMAL_EMULATION option will make this support available.
    17. 

  17. When it's enabled, sysfs node will be created as
    18. 

  18. /sys/devices/virtual/thermal/thermal_zone'zone id'/emul_temp.
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  19. 

  20. The sysfs node, 'emul_node', will contain value 0 for the initial state. When you input any
    21. 

  21. temperature you want to update to sysfs node, it automatically enable emulation mode and
    22. 

  22. current temperature will be changed into it.
    23. 

  23. (Exynos also supports user changeable delay time which would be used to delay of
    24. 

  24.  changing temperature. However, this node only uses same delay of real sensing time, 938us.)
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  25. 

  26. Exynos emulation mode requires synchronous of value changing and enabling. It means when you
    27. 

  27. want to update the any value of delay or next temperature, then you have to enable emulation
    28. 

  28. mode at the same time. (Or you have to keep the mode enabling.) If you don't, it fails to
    29. 

  29. change the value to updated one and just use last succeessful value repeatedly. That's why
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  30. this node gives users the right to change termerpature only. Just one interface makes it more
    31. 

  31. simply to use.
    32. 

  32. 

  33. Disabling emulation mode only requires writing value 0 to sysfs node.
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  34. 

  35. 

  36. TEMP	120 |
    37. 

  37. 	    |
    38. 

  38. 	100 |
    39. 

  39. 	    |
    40. 

  40. 	 80 |
    41. 

  41. 	    |		     	 	 +-----------
    42. 

  42. 	 60 |      		     	 |	    |
    43. 

  43. 	    |	           +-------------|          |
    44. 

  44. 	 40 |              |         	 |          |
    45. 

  45. 	    |		   |	     	 |          |
    46. 

  46. 	 20 |		   |	     	 |          +----------
    47. 

  47. 	    |	 	   |	     	 |          |          |
    48. 

  48. 	  0 |______________|_____________|__________|__________|_________
    49. 

  49. 		   A	    	 A	    A	   	       A     TIME
    50. 

  50. 		   |<----->|	 |<----->|  |<----->|	       |
    51. 

  51. 		   | 938us |  	 |	 |  |       |          |
    52. 

  52. emulation    :  0  50	   |  	 70      |  20      |          0
    53. 

  53. current temp :   sensor   50		 70         20	      sensor
    54.