cpu: kinetis_common: periph/timer using inefficient initialization

[kaspar030]

While analyzing the impact of using xtimer all over the place, kinetis_common based boards use a lot more code:

text    data    bss dec BOARD/BINDIRBASE

-792    -4  -84 -880    airfy-beacon
11772   148 2748    14668   oldbin
10980   144 2664    13788   bin

-784    -4  -124    -912    arduino-due
12028   152 2824    15004   oldbin
11244   148 2700    14092   bin

-3328   -98 -46 -3472   arduino-mega2560
14740   818 808 16366   oldbin
11412   720 762 12894   bin

-780    -4  -68 -852    cc2538dk
11576   148 2740    14464   oldbin
10796   144 2672    13612   bin

-716    -4  -60 -780    ek-lm4f120xl
11492   148 2788    14428   oldbin
10776   144 2728    13648   bin

-768    -4  -100    -872    f4vi1
13044   152 2760    15956   oldbin
12276   148 2660    15084   bin

-728    -4  -92 -824    fox
17784   148 2924    20856   oldbin
17056   144 2832    20032   bin

1352    -4  -60 1288    frdm-k64f
15928   1244    4900    22072   oldbin
17280   1240    4840    23360   bin

-776    -4  -92 -872    iotlab-m3
18452   148 2932    21532   oldbin
17676   144 2840    20660   bin

-732    -4  -92 -828    limifrog-v1
12960   148 2764    15872   oldbin
12228   144 2672    15044   bin

-728    -4  -92 -824    mbed_lpc1768
11312   148 2764    14224   oldbin
10584   144 2672    13400   bin
-768    -4  -100    -872    msbiot
13324   152 2784    16260   oldbin
12556   148 2684    15388   bin

1376    -4  -60 1312    mulle
17808   1268    4628    23704   oldbin
19184   1264    4568    25016   bin

2252    4   -64 2192    native
55100   536 60672   116308  oldbin
57352   540 60608   118500  bin

-792    -4  -84 -880    nrf51dongle
11796   148 2748    14692   oldbin
11004   144 2664    13812   bin

-792    -4  -84 -880    nrf6310
11772   148 2748    14668   oldbin
10980   144 2664    13788   bin

-780    -4  -100    -884    nucleo-f091
18568   152 2776    21496   oldbin
17788   148 2676    20612   bin

-768    -4  -100    -872    nucleo-f303
13000   148 2780    15928   oldbin
12232   144 2680    15056   bin

-768    -4  -100    -872    nucleo-f334
12744   148 2756    15648   oldbin
11976   144 2656    14776   bin

-732    -4  -92 -828    nucleo-l1
12960   148 2756    15864   oldbin
12228   144 2664    15036   bin

-780    -4  -68 -852    openmote
11484   148 2740    14372   oldbin
10704   144 2672    13520   bin

1352    -4  -60 1288    pba-d-01-kw2x
15996   1244    4284    21524   oldbin
17348   1240    4224    22812   bin

-792    -4  -84 -880    pca10000
11796   148 2748    14692   oldbin
11004   144 2664    13812   bin

-792    -4  -84 -880    pca10005
11776   148 2748    14672   oldbin
10984   144 2664    13792   bin

-780    -4  -68 -852    remote
12140   148 2740    15028   oldbin
11360   144 2672    14176   bin

-780    -4  -60 -844    saml21-xpro
11872   148 2844    14864   oldbin
11092   144 2784    14020   bin

-836    -4  -68 -908    samr21-xpro
15224   156 2740    18120   oldbin
14388   152 2672    17212   bin

-732    -4  -92 -828    spark-core
13668   148 2884    16700   oldbin
12936   144 2792    15872   bin

-780    -4  -92 -876    stm32f0discovery
14904   148 2764    17816   oldbin
14124   144 2672    16940   bin

-768    -4  -100    -872    stm32f3discovery
13004   148 2780    15932   oldbin
12236   144 2680    15060   bin

-768    -4  -92 -864    stm32f4discovery
13208   152 2768    16128   oldbin
12440   148 2676    15264   bin

-784    -4  -124    -912    udoo
12028   152 2824    15004   oldbin
11244   148 2700    14092   bin

-792    -4  -84 -880    yunjia-nrf51822
11760   148 2748    14656   oldbin
10968   144 2664    13776   bin

It seems that timer_init() (from the periph/timer interface) pulls in ~2kB of libgcc division code, while the (soon obsolete) hwtimer_arch implementation does not.

[jnohlgard]

I will refactor/rewrite the timer periph implementation on kinetis when I have time. I will add support for the low power timer as well then.

[jnohlgard]

the rework in #4065 should fix this eventually.

[jnohlgard]

Fixed by #4040