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Diffstat (limited to 'doc/driver-model/UDM-watchdog.txt')
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diff --git a/doc/driver-model/UDM-watchdog.txt b/doc/driver-model/UDM-watchdog.txt new file mode 100644 index 0000000..271bd26 --- /dev/null +++ b/doc/driver-model/UDM-watchdog.txt @@ -0,0 +1,334 @@ +The U-Boot Driver Model Project +=============================== +Watchdog device subsystem analysis +================================== + +Tomas Hlavacek <tmshlvck@gmail.com> +2012-03-09 + +I) Overview +----------- + +U-Boot currently implements an API for HW watchdog devices as explicit drivers +in drivers/watchdog directory. There are also drivers for both hardware and +software watchdog on particular CPUs implemented in arch/*/cpu/*/cpu.c. There +are macros in include/watchdog.h that selects between SW and HW watchdog and +assembly SW implementation. + +The current common interface comprises of one set out of these two possible +variants: + + 1) + void watchdog_reset(void); + int watchdog_disable(void); + int watchdog_init(void); + + 2) + void hw_watchdog_reset(void); + void hw_watchdog_init(void); + +The watchdog implementations are also spread through board/*/*.c that in +some cases. The API and semantics is in most cases same as the above +mentioned common functions. + + +II) Approach +------------ + + 1) New API + ---------- + + In the UDM each watchdog driver would register itself by a function + + int watchdog_device_register(struct instance *i, + const struct watchdog_device_ops *o); + + The structure being defined as follows: + + struct watchdog_device_ops { + int (*disable)(struct instance *i); + void (*reset)(struct instance *i); + }; + + The watchdog_init() function will be dissolved into probe() function. + + 2) Conversion thougths + ---------------------- + + Conversion of watchdog implementations to a new API could be divided + to three subsections: a) HW implementations, which are mostly compliant + to the above mentioned API; b) SW implementations, which are compliant + to the above mentioned API and c) SW implementations that are not compliant + to the API and has to be rectified or partially rewritten. + +III) Analysis of in-tree drivers +-------------------------------- + + 1) drivers/watchdog/at91sam9_wdt.c + ---------------------------------- + The driver is standard HW watchdog. Simple conversion is possible. + + + 2) drivers/watchdog/ftwdt010_wdt.c + ---------------------------------- + The driver is ad-hoc HW watchdog. Conversion has to take into account + driver parts spread in include/faraday/*. Restructuring the driver and + code cleanup has to be considered. + + + 3) arch/arm/cpu/arm1136/mx31/timer.c + ------------------------------------ + The driver is semi-standard ad-hoc HW watchdog. Conversion has to take + into account driver parts spread in the timer.c file. + + + 4) arch/arm/cpu/arm926ejs/davinci/timer.c + ----------------------------------------- + The driver is ad-hoc semi-standard HW watchdog. Conversion has to take + into account driver parts spread in the timer.c file. + + + 5) arch/arm/cpu/armv7/omap-common/hwinit-common.c + ------------------------------------------------- + The driver is non-standard ad-hoc HW watchdog. Conversion is possible + but functions has to be renamed and constants moved to another places. + + + 6) arch/arm/cpu/armv7/omap3/board.c + ----------------------------------- + The driver is non-standard ad-hoc HW watchdog. Conversion is possible + but functions has to be renamed and constants moved to another places. + + + 7) arch/blackfin/cpu/watchdog.c + ------------------------------- + The driver is standard HW watchdog. Simple conversion is possible. + + + 8) arch/m68k/cpu/mcf523x/cpu.c + ------------------------------ + The driver is standard HW watchdog. Simple conversion is possible. + + + 9) arch/m68k/cpu/mcf52x2/cpu.c + ------------------------------ + The driver is standard HW watchdog. Simple conversion is possible. + + + 10) arch/m68k/cpu/mcf532x/cpu.c + ------------------------------- + The driver is standard HW watchdog. Simple conversion is possible. + + + 11) arch/m68k/cpu/mcf547x_8x/cpu.c + ---------------------------------- + The driver is standard HW watchdog (there is slight naming convention + violation that has to be rectified). Simple conversion is possible. + + + 12) arch/powerpc/cpu/74xx_7xx/cpu.c + ----------------------------------- + The driver is standard HW watchdog. Simple conversion is possible. + + + 13) arch/powerpc/cpu/mpc512x/cpu.c + ---------------------------------- + The driver is standard HW watchdog. Simple conversion is possible. + + + 14) arch/powerpc/cpu/mpc5xx/cpu.c + --------------------------------- + The driver is standard HW watchdog. Simple conversion is possible. + + + 15) arch/powerpc/cpu/mpc5xxx/cpu.c + ---------------------------------- + The driver is standard HW watchdog. Simple conversion is possible. + + + 16) arch/powerpc/cpu/mpc8260/cpu.c + ---------------------------------- + The driver is standard HW watchdog. Simple conversion is possible. + + + 17) arch/powerpc/cpu/mpc83xx/cpu.c + ---------------------------------- + The driver is standard HW watchdog. Simple conversion is possible. + + + 18) arch/powerpc/cpu/mpc85xx/cpu.c + ---------------------------------- + The driver is standard HW watchdog. Simple conversion is possible. + + + 19) arch/powerpc/cpu/mpc86xx/cpu.c + ---------------------------------- + The driver is standard HW watchdog. Simple conversion is possible. + + + 20) arch/powerpc/cpu/mpc8xx/cpu.c + + The driver is standard HW watchdog. Simple conversion is possible. + + + 21) arch/powerpc/cpu/ppc4xx/cpu.c + --------------------------------- + The driver is standard HW watchdog. Simple conversion is possible. + + + 22) arch/sh/cpu/sh2/watchdog.c + ------------------------------ + The driver is standard HW watchdog. Simple conversion is possible. + + + 23) arch/sh/cpu/sh3/watchdog.c + ------------------------------ + The driver is standard HW watchdog. Simple conversion is possible. + + + 24) arch/sh/cpu/sh4/watchdog.c + ------------------------------ + The driver is standard HW watchdog. Simple conversion is possible. + + + 25) board/amcc/luan/luan.c + -------------------------- + The driver is standard HW watchdog. Simple conversion is possible. + + + 26) board/amcc/yosemite/yosemite.c + ---------------------------------- + The driver is standard HW watchdog. Simple conversion is possible. + + + 27) board/apollon/apollon.c + --------------------------- + The driver is standard HW watchdog however the watchdog_init() + function is called in early initialization. Simple conversion is possible. + + + 28) board/bmw/m48t59y.c + ----------------------- + Special watchdog driver. Dead code. To be removed. + + + 29) board/davedenx/qong/qong.c + ------------------------------ + The driver is standard HW watchdog. Simple conversion is possible. + + + 30) board/dvlhost/watchdog.c + ---------------------------- + The driver is standard HW watchdog. Simple conversion is possible. + + + 31) board/eNET/eNET.c + --------------------- + The driver is standard HW watchdog. Simple conversion is possible. + + + 32) board/eltec/elppc/elppc.c + ----------------------------- + The driver is standard HW watchdog. Simple conversion is possible. + + + 33) board/enbw/enbw_cmc/enbw_cmc.c + ---------------------------------- + Only function proxy call. Code cleanup needed. + + + 34) board/freescale/mx31pdk/mx31pdk.c + ------------------------------------- + Only function proxy call. Code cleanup needed. + + + 35) board/gth2/gth2.c + --------------------- + The driver is standard HW watchdog. Simple conversion is possible. + + + 36) board/lwmon5/lwmon5.c + ------------------------- + The driver is standard HW watchdog. Simple conversion is possible. + + + 37) board/manroland/mucmc52/mucmc52.c + ------------------------------------- + The driver is standard HW watchdog. Simple conversion is possible. + + + 38) board/manroland/uc101/uc101.c + --------------------------------- + The driver is standard HW watchdog. Simple conversion is possible. + + + 39) board/mousse/m48t59y.c + -------------------------- + Special watchdog driver. Dead code. To be removed. + + + 40) board/mvblue/mvblue.c + ------------------------- + The driver is standard HW watchdog. Simple conversion is possible. + + + 41) board/netphone/netphone.c + ----------------------------- + The driver is standard HW watchdog. Simple conversion is possible. + + + 42) board/netta/netta.c + ----------------------- + The driver is standard HW watchdog. Simple conversion is possible. + + + 43) board/netta2/netta2.c + ------------------------- + The driver is standard HW watchdog. Simple conversion is possible. + + + 44) board/omicron/calimain/calimain.c + ------------------------------------- + Only function proxy call. Code cleanup needed. + + + 45) board/pcippc2/pcippc2.c + --------------------------- + The driver is standard HW watchdog. Simple conversion is possible. + + + 46) board/pcs440ep/pcs440ep.c + ----------------------------- + The driver is standard HW watchdog. Simple conversion is possible. + + + 47) board/stx/stxxtc/stxxtc.c + ----------------------------- + The driver is standard HW watchdog. Simple conversion is possible. + + + 48) board/ti/omap2420h4/omap2420h4.c + ------------------------------------ + The driver is standard HW watchdog. Simple conversion is possible. + + + 49) board/ttcontrol/vision2/vision2.c + ------------------------------------- + The driver is standard HW watchdog but namespace is polluted by + non-standard macros. Simple conversion is possible, code cleanup + needed. + + + 50) board/v38b/v38b.c + --------------------- + The driver is standard HW watchdog. Simple conversion is possible. + + + 51) board/ve8313/ve8313.c + ------------------------- + The driver is standard HW watchdog. Simple conversion is possible. + + + 52) board/w7o/watchdog.c + ------------------------ + The driver is standard HW watchdog. Simple conversion is possible. |