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annotate src/cs/system/main/gcc/irqfiq.S @ 214:adfdbcd360fd

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backlight evolution: API between Condat driver and MFW With this change, the API between the Condat backlight driver and its user in MFW now carries more abstract backlight state codes (fully off, fully on, in call, charging boot mode) instead of 0-255 levels. This change is needed in order to more properly support different hardware targets with different capabilities and approaches in terms of backlight handling.
author Mychaela Falconia <falcon@freecalypso.org>
date Fri, 23 Apr 2021 23:52:02 +0000
parents 4e78acac3d88
children
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4e78acac3d88 src/{condat,cs,gpf,nucleus}: import from Selenite
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1 /*
4e78acac3d88 src/{condat,cs,gpf,nucleus}: import from Selenite
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2 * This module contains the assembly shells for IRQ and FIQ, separated
4e78acac3d88 src/{condat,cs,gpf,nucleus}: import from Selenite
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3 * from the architectured vectors only by some simple unconditional
4e78acac3d88 src/{condat,cs,gpf,nucleus}: import from Selenite
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4 * branch instructions.
4e78acac3d88 src/{condat,cs,gpf,nucleus}: import from Selenite
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5 *
4e78acac3d88 src/{condat,cs,gpf,nucleus}: import from Selenite
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6 * Note that TI's way of handling interrupts sacrifices Nucleus' ability
4e78acac3d88 src/{condat,cs,gpf,nucleus}: import from Selenite
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7 * to nest interrupts and minimize the IRQ-disabled window: if my (Falcon's)
4e78acac3d88 src/{condat,cs,gpf,nucleus}: import from Selenite
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8 * understanding is correct, TI's code leaves all further IRQs disabled
4e78acac3d88 src/{condat,cs,gpf,nucleus}: import from Selenite
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9 * for the full execution duration of an IRQ handler. (IRQ handlers are
4e78acac3d88 src/{condat,cs,gpf,nucleus}: import from Selenite
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10 * really LISRs, but TI's GSM fw does not use Nucleus' LISR framework.)
4e78acac3d88 src/{condat,cs,gpf,nucleus}: import from Selenite
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11 */
4e78acac3d88 src/{condat,cs,gpf,nucleus}: import from Selenite
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12
4e78acac3d88 src/{condat,cs,gpf,nucleus}: import from Selenite
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13 .text
4e78acac3d88 src/{condat,cs,gpf,nucleus}: import from Selenite
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14 .code 32
4e78acac3d88 src/{condat,cs,gpf,nucleus}: import from Selenite
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15
4e78acac3d88 src/{condat,cs,gpf,nucleus}: import from Selenite
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16 .globl _INT_IRQ
4e78acac3d88 src/{condat,cs,gpf,nucleus}: import from Selenite
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17 _INT_IRQ:
4e78acac3d88 src/{condat,cs,gpf,nucleus}: import from Selenite
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18 STMDB sp!,{r0-r4} @ used to be a1-a4
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19
4e78acac3d88 src/{condat,cs,gpf,nucleus}: import from Selenite
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20 /*
4e78acac3d88 src/{condat,cs,gpf,nucleus}: import from Selenite
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21 * Thanks to TI for discovering and documenting this apparent ARM7TDMI bug:
4e78acac3d88 src/{condat,cs,gpf,nucleus}: import from Selenite
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22
4e78acac3d88 src/{condat,cs,gpf,nucleus}: import from Selenite
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23 BUG correction 1st part -------------------
4e78acac3d88 src/{condat,cs,gpf,nucleus}: import from Selenite
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24 It looks like there is an issue with ARM7 IRQ masking in the CPSR register
4e78acac3d88 src/{condat,cs,gpf,nucleus}: import from Selenite
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25 which leads to crashes in Nucleus+ scheduler.
4e78acac3d88 src/{condat,cs,gpf,nucleus}: import from Selenite
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26 Basically the code below (correct as LOCKOUT = 0xC0) is used in many places by N+ but do not
4e78acac3d88 src/{condat,cs,gpf,nucleus}: import from Selenite
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27 prevent from having an interrupt after the execution of the third line (I mean execution, not
4e78acac3d88 src/{condat,cs,gpf,nucleus}: import from Selenite
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28 fetch).
4e78acac3d88 src/{condat,cs,gpf,nucleus}: import from Selenite
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29 MRS a1,CPSR ; Pickup current CPSR
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30 ORR a1,a1,#LOCKOUT ; Build interrupt lockout value
4e78acac3d88 src/{condat,cs,gpf,nucleus}: import from Selenite
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31 MSR CPSR,a1 ; Lockout interrupts
4e78acac3d88 src/{condat,cs,gpf,nucleus}: import from Selenite
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32 * IRQ INTERRUPT ! *
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33 Next instructions...
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34
4e78acac3d88 src/{condat,cs,gpf,nucleus}: import from Selenite
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35 SW workaround:
4e78acac3d88 src/{condat,cs,gpf,nucleus}: import from Selenite
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36 When a task is interrupted at this point an interrupted context is stored on its task and will
4e78acac3d88 src/{condat,cs,gpf,nucleus}: import from Selenite
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37 be resumed later on at the next instruction but to make a long story short it leads to some
4e78acac3d88 src/{condat,cs,gpf,nucleus}: import from Selenite
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38 problem as the OS does not expect to be interrupted there.
4e78acac3d88 src/{condat,cs,gpf,nucleus}: import from Selenite
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39 Further testing tends to show that the CPSR *seems* to be loaded with the proper masking value
4e78acac3d88 src/{condat,cs,gpf,nucleus}: import from Selenite
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40 but that the IRQ is still triggered (has been hardwarewise requested during the instruction
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41 exectution by the ARM7 core?)
4e78acac3d88 src/{condat,cs,gpf,nucleus}: import from Selenite
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42 */
4e78acac3d88 src/{condat,cs,gpf,nucleus}: import from Selenite
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43
4e78acac3d88 src/{condat,cs,gpf,nucleus}: import from Selenite
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44 MRS a1,spsr @ check for the IRQ bug:
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45 TST a1,#0x80 @ if the I - flag is set,
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46 BNE IRQBUG @ then postpone execution of this IRQ
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47 /* Bug correction 1st part end --------------- */
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48
4e78acac3d88 src/{condat,cs,gpf,nucleus}: import from Selenite
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49 SUB r4,lr,#4 @ Save IRQ's lr (return address)
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50 BL TCT_Interrupt_Context_Save @ Call context save routine
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51
4e78acac3d88 src/{condat,cs,gpf,nucleus}: import from Selenite
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52 BL IQ_IRQ_isr @ Call int. service routine
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53
4e78acac3d88 src/{condat,cs,gpf,nucleus}: import from Selenite
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54 /* IRQ interrupt processing is complete. Restore context- Never
4e78acac3d88 src/{condat,cs,gpf,nucleus}: import from Selenite
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55 returns! */
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56 B TCT_Interrupt_Context_Restore
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57
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58 /* BUG correction 2nd part ------------------ */
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59 IRQBUG: LDMFD sp!,{r0-r4} @ return from interrupt
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60 SUBS pc,r14,#4
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61 /* BUG correction 2nd part end -------------- */
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62
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63 .globl _INT_FIQ
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64 _INT_FIQ:
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65 STMDB sp!,{r0-r4} @ used to be a1-a4
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66 SUB r4,lr,#4 @ Save FIQ's lr (return address)
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67 BL TCT_Interrupt_Context_Save @ Call context save routine
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68
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69 BL IQ_FIQ_isr @ Call the FIQ ISR
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70
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71 /* FIQ interrupt processing is complete. Restore context- Never
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72 returns! */
4e78acac3d88 src/{condat,cs,gpf,nucleus}: import from Selenite
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73 B TCT_Interrupt_Context_Restore