Hi all, The series adds thermal support to Renesas R-Car Gen3 SoCs. It's tested on Salvator-X H3 and M3-W SoC. Wolfram asked me to have a look at the comments for v4 and to try and rework the temperature formulas to work with only ints and if it worked out resend the series. I have reworked code in 2/4 but kept Wolfram as the author and added my SoB, hope this is OK. Reworking the formulas involved moving from s64 to int as the data type used to store coefficients used in binary scaled fixed point calculations. By examining the largest values which could be produced in these calculations a shift of 7 is the maximum scaling which is possible and still fit inside an int, previously with s64 the decimal scaling was 1000. Changing the decimal scaling also reduces the accuracy of the calculations. In my tests this was hardly noticeable as the granularity of the reported temperature to user-space is 0.5C, comparing the value reported in the s64 vs int implementation only differ very slightly when it rounded the value to the next 0.5C level. However the formulas used to calculate the coefficients are not documented and none obvious (at lest not to me) so given different initial values to calculate the coefficients the error might become larger. Therefore I would like to ask Morimoto-san and/or Khiem to provide or proxy testing of this less accurate formula and feedback if it's OK, let me know if there is anything I can do to help out. Changes since v5 - Switch fixpoint scaling from decimal with a factor 100 to binary with a shift of 7 bits to increase accuracy. In v5 decimal scaling was used since it closest resembled the v4 implementation of a decimal scaling with 1000 as a factor. The big change in v5 was to fit all calculations inside a int instead of s64. After discussions with Geert and Wolfram it became apparent that disregarding what scaling method used the change in scaling to fit inside a int needs to be reverified by Morimoto-san or Khiem so we might as well have as much accuracy as possible. - Dropped macro for fixed point multiplication. All uses where between a scaled variable and a none scaled constant so upscaling the constant just to then downscale the product where unneeded and the product could overflow before it was downscaled. - Change calculation of one constant (tj_2) to not be upscaled before it's divided. This is how it's done in the BSP and it could overflow if done with upscaled numbers. As a good side effect the final temperature value more closely match the BSP value. This should never have been changed to work with upscaled variables in v5. - Rename fixed point calculation macros prefix from SCALE_ to FIXPT_ - Use DIV_ROUND_CLOSEST in FIXPT_DIV macro. In theory when PTAT and THCODE values are read from hardware (not available yet) DIV_ROUND_CLOSEST could be called with a negative divisor which currently is not supported by DIV_ROUND_CLOSEST. I have submitted a patch to fix DIV_ROUND_CLOSEST to support this '[RFC/PATCH] linux/kernel.h: Fix DIV_ROUND_CLOSEST to support negative'. If that patch is rejected something similar needs to be added as local code here before PTAT and THCODE values can be read from registers. - Add spaces between all operands in FIXPT_ macros - Squashed patch 5/5 into 2/5. Changes since v4: - Use only 32 bit ints to convert from register value to temperature. - Merge and simplify temp calculation functions. - Document what I known about the temprature conversion formulas. - Add new patch 5/5 which fixes a waring printout caused by trying to get temp before hardware is ready on r8a7795. - Fixed a few checkpatch warnings. Wolfram Sang (4): thermal: rcar_gen3_thermal: Document the R-Car Gen3 thermal: rcar_gen3_thermal: Add R-Car Gen3 thermal driver arm64: dts: r8a7795: Add R-Car Gen3 thermal support arm64: dts: r8a7796: Add R-Car Gen3 thermal support .../bindings/thermal/rcar-gen3-thermal.txt | 56 ++++ arch/arm64/boot/dts/renesas/r8a7795.dtsi | 58 ++++ arch/arm64/boot/dts/renesas/r8a7796.dtsi | 58 ++++ drivers/thermal/Kconfig | 9 + drivers/thermal/Makefile | 1 + drivers/thermal/rcar_gen3_thermal.c | 335 +++++++++++++++++++++ 6 files changed, 517 insertions(+) create mode 100644 Documentation/devicetree/bindings/thermal/rcar-gen3-thermal.txt create mode 100644 drivers/thermal/rcar_gen3_thermal.c -- 2.11.0
