FreeCalypso > hg > freecalypso-tools

annotate target-utils/flash-boot-test/uartinit.S @ 684:7674abe34c25

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doc/Loadtools-usage: -t option documented
author Mychaela Falconia <falcon@freecalypso.org>
date Tue, 10 Mar 2020 07:24:47 +0000
parents cc6594a7fc7a
children
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cc6594a7fc7a target-utils/flash-boot-test: added UART init, needed for mode 1
Mychaela Falconia <falcon@freecalypso.org>
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1 /*
cc6594a7fc7a target-utils/flash-boot-test: added UART init, needed for mode 1
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2 * The UART initialization code in this assembly module has been lifted
cc6594a7fc7a target-utils/flash-boot-test: added UART init, needed for mode 1
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3 * from the disassembly of the Calypso boot ROM, and slightly adapted
cc6594a7fc7a target-utils/flash-boot-test: added UART init, needed for mode 1
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4 * for our needs.
cc6594a7fc7a target-utils/flash-boot-test: added UART init, needed for mode 1
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5 */
cc6594a7fc7a target-utils/flash-boot-test: added UART init, needed for mode 1
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6
cc6594a7fc7a target-utils/flash-boot-test: added UART init, needed for mode 1
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7 .text
cc6594a7fc7a target-utils/flash-boot-test: added UART init, needed for mode 1
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8 .code 32
cc6594a7fc7a target-utils/flash-boot-test: added UART init, needed for mode 1
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9 .globl uart_init
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10
cc6594a7fc7a target-utils/flash-boot-test: added UART init, needed for mode 1
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11 uart_init:
cc6594a7fc7a target-utils/flash-boot-test: added UART init, needed for mode 1
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12 stmfd sp!, {r4-r11,lr}
cc6594a7fc7a target-utils/flash-boot-test: added UART init, needed for mode 1
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13 @ prepare UART init values
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14 mov r11, #3
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15 mov r5, #0
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16 mov r10, #7 @ baud rate divisor for 115200 baud
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17 mov r9, #0x80
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18 mov r7, #0xbf
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19 mov r4, #7
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20 @ UART base address
cc6594a7fc7a target-utils/flash-boot-test: added UART init, needed for mode 1
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21 ldr r6, =uart_base
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22 ldr r12, [r6]
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23 add r3, r12, #8
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24 @ R3 points to register 8 (MDR1)
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25 @ write 07 into it: reset mode
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26 strb r4, [r3]
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27 add r0, r12, #3
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28 @ R0 points to register 3 (LCR)
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29 @ write BF into it: map in the extended registers
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30 strb r7, [r0]
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31 add r1, r12, #2
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32 @ R1 points to register 2: EFR under current mapping
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33 @ set bit 4: enable enhanced functions
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34 ldrb r8, [r1]
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35 orr r8, r8, #0x10
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36 strb r8, [r1]
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37 @ write 80 into LCR: map in the baud rate divisor registers
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38 strb r9, [r0]
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39 @ reg 2 (pointed to by R1) is now IIR/FCR
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40 @ write 07 into FCR: FIFOs enabled and cleared, no DMA
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41 strb r4, [r1]
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42 @ write BF into LCR again
cc6594a7fc7a target-utils/flash-boot-test: added UART init, needed for mode 1
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43 strb r7, [r0]
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44 @ load baud rate divisor
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45 strb r10, [r12]
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46 strb r5, [r12, #1]
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47 @ write 03 into LCR: restore normal registers, 8N1
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48 strb r11, [r0]
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49 @ write 00 into MDR1: plain UART mode
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50 strb r5, [r3]
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51 ldmfd sp!, {r4-r11,pc}