The chip has a pair of thermal meters and nothing was reading them. This adds a
`temp` command that prints the current reading next to the one taken at power-on.
The result register at 0x340 splits a 19 bit value across two fields: bits 18:3
live in the low 16 bits, bits 2:0 in bits 18:16, with the sign at bit 18, degrees
in 17:10 and a fraction below. The nice part of that layout is that the degrees
fall out of a shift of the low half, so the conversion stays 16 bit.
The meter comes out of reset latched: the register keeps whatever was measured
when the board powered up and then never moves. Four samples 40 s apart came back
identical down to the raw ADC, and 0x340 matched the power-on register at 0x350.
Clearing bit 2 of the control register at 0x338 during init is what makes it live.
Measured on an SWTGW218AS: 58.7 to 59.5 C while running, with the power-on
register still showing the 49.2 C it started from. For what it is worth, the
scale lines up three ways: the threshold register reads -40 and +125, the slope
from warm-up works out at 4450 LSB/C, and the slope between the two meters at
4388 LSB/C.
We only read the meter that is up after boot. The other sits in reset with no
coefficients, so it would just repeat its power-on value.
Costs 231 bytes in BANK2.
The common segment is the scarce one: sixteen kilobytes shared by every bank,
and before this it had about 2.5 kB left. Most of what moves here runs once at
startup and does not have to sit in it. The two SerDes helpers are the
exception: the link-change handler and the SFP polling both reach sds_config()
while the switch is running, so they are not startup-only. None of it is
reached from an interrupt.
boot.c takes setup_i2c, init_smi, nic_setup, rtl8373_revision, rtl8224_enable,
early_boot_handle_button, set_hostname_default and the two SerDes helpers.
BANK3 is enabled with the linker flag; nothing else in the build needed
changing.
Everything moved is declared __banked, since every caller is outside BANK3:
main() and friends run from the common area and rtl837x_init.c calls
sds_config() and sds_config_mac() from BANK2. The calls the moved code makes
outward were already banked, so that side needed no work.
Common segment 13393 -> 10137 bytes, leaving 5787 free rather than 2531.
BANK3 holds 3732. All 34 machines in machine.h build and link. Walking
the generated assembly for plain lcalls that cross a bank boundary finds none
among 2808 calls; those build cleanly and only fail at run time, so it seemed
worth checking by machine rather than by eye.
d00f
Lynn-Becky
logicog