BFE Engineering
42fb386f60
Replace every em dash with real punctuation (rewrites, not hyphen swaps) in docs, code comments, scripts, configs, and the port records; convert en dashes, curly quotes, ellipsis glyphs, arrows, and section signs to ASCII; drop machine-writing tell phrases from living docs. ADR titles now use a colon. The M2 bring-up DTS model string carried an em dash into the patch series and its record echoes; fixed at both, and the full series re-verified to apply cleanly onto pristine 6.18.46. One comment in freshness.h deliberately names the em dash glyph the UI renders as the unknown mark; that is data, kept as prose naming it. Verified: cargo tests (sim, config-lint, rs485-bridge), shellcheck, both driver MC/DC harnesses, patches-apply.
99 lines
3.6 KiB
C
99 lines
3.6 KiB
C
/*
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* HPMCU mailbox echo firmware for the RV1106 (Syntacore SCR1, RV32IMC).
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*
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* Purpose: prove a fully-open A7 <-> HPMCU hardware-mailbox round-trip on our
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* self-built Linux 6.18. The A7 (Linux) writes a {cmd,dat} pair into the
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* mailbox A2B registers; this core polls A2B_STATUS, reads the pair, echoes it
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* verbatim into the B2A registers (which raises the B2A doorbell IRQ back to
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* Linux), and acks. No RT-Thread, no interrupts on the MCU side, machine mode
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* only: a polling loop, exactly like the watchdog firmware.
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*
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* The mailbox IP is at 0xFF5C0000 (the HPMCU-connected instance: Linux resets
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* it via SRST_CORE_MCU, the vendor MCU CMSIS header hard-codes MBOX_BASE
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* 0xFF5C0000). Register model is IP-identical to rk3368 (mainline
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* rockchip-mailbox.c): writing A2B_CMD(x) is the doorbell (hardware sets the
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* A2B_STATUS bit); writing B2A_CMD(x) signals Linux (B2A_STATUS + IRQ).
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*
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* Both the mailbox registers and hpmcu_sram sit in the GRF "peripheral
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* uncached" window (0xFF000000..0xFFC00000) configured at MCU release, so both
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* sides see each other's writes with no cache maintenance (same property the
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* watchdog SRAM mailbox relies on).
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*
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* Loaded + started by the proven flared/hpmcu.rs SRAM sequence
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* (0xFF6FE000 load addr, CORECRU reset hold/release), NOT the 0x40000
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* boot-load path (that bricks a non-TB board; see boot-loaded-mcu-0x40000
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* hazard). Fits the 8K hpmcu_sram budget (this is a few hundred bytes).
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*/
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#include <stdint.h>
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#define REG32(a) (*(volatile uint32_t *)(uintptr_t)(a))
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/* Mailbox IP (HPMCU-connected instance): offsets match rockchip-mailbox.c. */
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#define MBOX_BASE 0xFF5C0000u
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#define A2B_INTEN REG32(MBOX_BASE + 0x00)
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#define A2B_STATUS REG32(MBOX_BASE + 0x04)
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#define A2B_CMD(x) REG32(MBOX_BASE + 0x08 + (x) * 8)
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#define A2B_DAT(x) REG32(MBOX_BASE + 0x0c + (x) * 8)
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#define B2A_STATUS REG32(MBOX_BASE + 0x2C)
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#define B2A_CMD(x) REG32(MBOX_BASE + 0x30 + (x) * 8)
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#define B2A_DAT(x) REG32(MBOX_BASE + 0x34 + (x) * 8)
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#define NUM_CHANS 4
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/*
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* Liveness window in hpmcu_sram (reuse the watchdog mailbox layout at
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* 0xFF6FFF00 so Linux tooling can read it the same way). We only touch the
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* MCU-owned slots; the echo firmware does NOT run the watchdog, so it never
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* touches MB_MAGIC/MB_COUNTER or fires a reset.
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*
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* +0x08 mcu_state : 'M','B','O','X' (0x584F424D LE) once the echo loop runs
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* +0x0c last_cmd : the last cmd echoed (debug)
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* +0x10 echo_cnt : number of messages echoed (heartbeat / proof-of-life)
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*/
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#define SRAM_DBG_BASE 0xFF6FFF00u
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#define DBG_STATE REG32(SRAM_DBG_BASE + 0x08)
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#define DBG_LASTCMD REG32(SRAM_DBG_BASE + 0x0c)
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#define DBG_ECHOCNT REG32(SRAM_DBG_BASE + 0x10)
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#define STATE_MBOX 0x584F424Du /* "MBOX" (LE bytes 'M','B','O','X') */
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void main(void)
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{
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uint32_t echoes = 0;
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DBG_STATE = STATE_MBOX;
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DBG_LASTCMD = 0;
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DBG_ECHOCNT = 0;
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/* Enable the A2B doorbell for all channels: without A2B_INTEN set on the
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* receiver (MCU) side, an A7 write to A2B_CMD does not raise A2B_STATUS,
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* so our poll below never sees a message. (Symmetric to the A7 controller
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* setting B2A_INTEN in its startup.) */
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A2B_INTEN = (1u << NUM_CHANS) - 1;
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for (;;) {
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uint32_t status = A2B_STATUS;
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int ch;
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for (ch = 0; ch < NUM_CHANS; ch++) {
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if (status & (1u << ch)) {
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uint32_t cmd = A2B_CMD(ch);
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uint32_t dat = A2B_DAT(ch);
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/* Echo verbatim. Writing B2A_CMD raises the B2A
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* doorbell (hardware sets B2A_STATUS -> Linux
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* IRQ / readable status). */
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B2A_CMD(ch) = cmd;
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B2A_DAT(ch) = dat;
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/* Ack: clear our A2B_STATUS bit (write-1-clear). */
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A2B_STATUS = (1u << ch);
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DBG_LASTCMD = cmd;
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DBG_ECHOCNT = ++echoes;
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}
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}
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}
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}
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