exynos_thermal_emulation.rst (2207B)
1===================== 2Exynos Emulation Mode 3===================== 4 5Copyright (C) 2012 Samsung Electronics 6 7Written by Jonghwa Lee <jonghwa3.lee@samsung.com> 8 9Description 10----------- 11 12Exynos 4x12 (4212, 4412) and 5 series provide emulation mode for thermal 13management unit. Thermal emulation mode supports software debug for 14TMU's operation. User can set temperature manually with software code 15and TMU will read current temperature from user value not from sensor's 16value. 17 18Enabling CONFIG_THERMAL_EMULATION option will make this support 19available. When it's enabled, sysfs node will be created as 20/sys/devices/virtual/thermal/thermal_zone'zone id'/emul_temp. 21 22The sysfs node, 'emul_node', will contain value 0 for the initial state. 23When you input any temperature you want to update to sysfs node, it 24automatically enable emulation mode and current temperature will be 25changed into it. 26 27(Exynos also supports user changeable delay time which would be used to 28delay of changing temperature. However, this node only uses same delay 29of real sensing time, 938us.) 30 31Exynos emulation mode requires synchronous of value changing and 32enabling. It means when you want to update the any value of delay or 33next temperature, then you have to enable emulation mode at the same 34time. (Or you have to keep the mode enabling.) If you don't, it fails to 35change the value to updated one and just use last succeessful value 36repeatedly. That's why this node gives users the right to change 37termerpature only. Just one interface makes it more simply to use. 38 39Disabling emulation mode only requires writing value 0 to sysfs node. 40 41:: 42 43 44 TEMP 120 | 45 | 46 100 | 47 | 48 80 | 49 | +----------- 50 60 | | | 51 | +-------------| | 52 40 | | | | 53 | | | | 54 20 | | | +---------- 55 | | | | | 56 0 |______________|_____________|__________|__________|_________ 57 A A A A TIME 58 |<----->| |<----->| |<----->| | 59 | 938us | | | | | | 60 emulation : 0 50 | 70 | 20 | 0 61 current temp: sensor 50 70 20 sensor