rebbarb/gc_bba_test/source/tests.c

#include "tests.h"
#include "bba.h"
#include <stdio.h>
#include <string.h>
#include <unistd.h>
#include <ogc/lwp_watchdog.h>

int g_ncra_reset_done = 0;

static void msleep(u32 ms) { usleep(ms * 1000); }

/* ───────────────────────── suite 1: identity ───────────────────────── */

/* Is the EXI link demonstrably healthy apart from address 0?
 *
 * Needed because `id_phase` is a ONE-SHOT in the FPGA, cleared by the first
 * NCRA reset, and g_ncra_reset_done only tracks resets THIS RUN of the test
 * app issued.  That flag is software state standing in for hardware state, and
 * the two come apart as soon as a build is delivered over the wire: netboot
 * replaces the DOL and restarts the app with the flag clear, while the FPGA
 * keeps running with id_phase already spent by the previous run.  The ID tests
 * then query address 0, get NCRA back -- correct behaviour -- and report a
 * FAILURE for it.  Reflashing the FPGA is the only thing that restores it.
 *
 * HIPR and NWAYS are hardwired constants in the register file and do not
 * depend on id_phase, so if BOTH read correctly the EXI path is fine and a
 * wrong answer at address 0 can only be a spent id_phase.  If they are wrong
 * too, something real is broken and the test must still fail. */
static int iface_alive(void)
{
	return bba_r8(REG_HIPR)  == HIPR_PRESENT &&
	       bba_r8(REG_NWAYS) == NWAYS_LINKUP;
}

static int t_devid(char *m, size_t n)
{
	u8 b[4];
	int rc;
	if (g_ncra_reset_done) {
		snprintf(m, n, "skipped: id_phase is a one-shot; reflash/reset the FPGA");
		return 2;
	}
	if ((rc = bba_devid(b)) < 0) { snprintf(m, n, "EXI error %d", rc); return 1; }
	if (b[0]==0x04 && b[1]==0x02 && b[2]==0x02 && b[3]==0x00) {
		snprintf(m, n, "%02X %02X %02X %02X (want 04 02 02 00)",
		         b[0], b[1], b[2], b[3]);
		return 0;
	}
	if (iface_alive()) {
		snprintf(m, n, "%02X %02X %02X %02X: id_phase spent, reflash FPGA",
		         b[0], b[1], b[2], b[3]);
		return 2;
	}
	snprintf(m, n, "%02X %02X %02X %02X (want 04 02 02 00)", b[0], b[1], b[2], b[3]);
	return 1;
}

static int t_hipr(char *m, size_t n)
{
	int v = bba_r8(REG_HIPR);
	if (v < 0) { snprintf(m, n, "EXI error %d", v); return 1; }
	snprintf(m, n, "0x%02X (want 0x%02X)", v, HIPR_PRESENT);
	return v == HIPR_PRESENT ? 0 : 1;
}

static int t_nways(char *m, size_t n)
{
	int v = bba_r8(REG_NWAYS);
	if (v < 0) { snprintf(m, n, "EXI error %d", v); return 1; }
	snprintf(m, n, "0x%02X (want 0x%02X = 100M full duplex)", v, NWAYS_LINKUP);
	return v == NWAYS_LINKUP ? 0 : 1;
}

/* ───────────────────────── suite 2: registers ──────────────────────── */

static int rw_check(u16 addr, const u8 *pat, u32 len, const u8 *restore,
                    char *m, size_t n, const char *what)
{
	u8 got[4];
	int rc;
	if ((rc = bba_write(addr, pat, len)) < 0) { snprintf(m, n, "write failed %d", rc); return 1; }
	if ((rc = bba_read(addr, got, len)) < 0)  { snprintf(m, n, "read failed %d", rc);  return 1; }
	if (restore) bba_write(addr, restore, len);
	if (memcmp(got, pat, len) != 0) {
		snprintf(m, n, "%s readback %02X %02X %02X %02X", what,
		         got[0], len>1?got[1]:0, len>2?got[2]:0, len>3?got[3]:0);
		return 1;
	}
	snprintf(m, n, "%s wrote+read back %u bytes OK", what, (unsigned)len);
	return 0;
}

static int t_par_lo(char *m, size_t n)
{
	static const u8 pat[4] = {0xDE,0xAD,0xBE,0xEF};
	static const u8 def[4] = {0x00,0x09,0xBF,0x00};
	return rw_check(REG_PAR0, pat, 4, def, m, n, "PAR0-3");
}

static int t_par_hi(char *m, size_t n)
{
	static const u8 pat[2] = {0x5A,0xA5};
	static const u8 def[2] = {0x00,0x01};
	return rw_check(REG_PAR4, pat, 2, def, m, n, "PAR4-5");
}

static int t_imr(char *m, size_t n)
{
	int v;
	if (bba_w8(REG_IMR, 0x86) < 0) { snprintf(m, n, "write failed"); return 1; }
	v = bba_r8(REG_IMR);
	snprintf(m, n, "0x%02X (want 0x86)", v);
	return v == 0x86 ? 0 : 1;
}

static int t_ir_w1c(char *m, size_t n)
{
	int before, after;
	before = bba_r8(REG_IR);
	if (before < 0) { snprintf(m, n, "read failed"); return 1; }
	if (bba_w8(REG_IR, 0xFF) < 0) { snprintf(m, n, "write failed"); return 1; }
	after = bba_r8(REG_IR);
	snprintf(m, n, "0x%02X -> write 0xFF -> 0x%02X (want 0x00)", before, after);
	return after == 0x00 ? 0 : 1;
}

/* ─────────────────────── suite 3: reset & control ──────────────────── */

static int t_ncra_reset(char *m, size_t n)
{
	int i, v;
	if (bba_w8(REG_NCRA, NCRA_RESET) < 0) { snprintf(m, n, "write failed"); return 1; }
	g_ncra_reset_done = 1;
	for (i = 0; i < 50; i++) {
		v = bba_r8(REG_NCRA);
		if (v < 0) { snprintf(m, n, "read failed"); return 1; }
		if (!(v & NCRA_RESET)) {
			snprintf(m, n, "self-cleared after %d poll(s)", i);
			/* the W5100 re-inits behind this: RSTn pulse + 83 ms settle x2 */
			msleep(400);
			return 0;
		}
		msleep(5);
	}
	snprintf(m, n, "RESET bit never cleared (NCRA=0x%02X)", v);
	return 1;
}

static int t_ncra_sr(char *m, size_t n)
{
	int v;
	if (bba_w8(REG_NCRA, NCRA_SR) < 0) { snprintf(m, n, "write failed"); return 1; }
	v = bba_r8(REG_NCRA);
	snprintf(m, n, "0x%02X (want 0x%02X, start-receive set)", v, NCRA_SR);
	return v == NCRA_SR ? 0 : 1;
}

/* ──────────────────── suite 4: EXI link integrity ──────────────────── */

static int t_repeat(char *m, size_t n)
{
	int i, bad = 0;
	for (i = 0; i < 200; i++)
		if (bba_r8(REG_NWAYS) != NWAYS_LINKUP) bad++;
	snprintf(m, n, "%d/200 reads wrong at EXI speed index %u", bad, (unsigned)bba_speed);
	return bad == 0 ? 0 : 1;
}

static int t_speed_sweep(char *m, size_t n)
{
	u32 saved = bba_speed, s;
	u32 best = 0;
	int any = 0;
	char buf[40];
	int off = 0;
	buf[0] = 0;
	for (s = 0; s <= EXI_SPEED32MHZ; s++) {
		int i, bad = 0;
		bba_speed = s;
		for (i = 0; i < 40; i++)
			if (bba_r8(REG_NWAYS) != NWAYS_LINKUP) bad++;
		off += snprintf(buf + off, sizeof(buf) - off, "%s%u", s ? "," : "",
		                (unsigned)(bad ? 0 : 1));
		if (!bad) { best = s; any = 1; }
	}
	bba_speed = saved;
	/* `best` of 0 is ambiguous (index 0 works vs nothing works), so report
	 * the per-index map and say NONE explicitly. */
	if (!any)
		snprintf(m, n, "ok=[%s] NONE work - not an oversampling issue", buf);
	else
		snprintf(m, n, "ok=[%s] highest good idx=%u (5=27MHz)", buf,
		         (unsigned)best);
	return (any && best >= EXI_SPEED32MHZ) ? 0 : 1;
}

static int t_gap_sweep(char *m, size_t n)
{
	static const u32 gaps[] = {0, 1, 2, 4, 8, 16, 32};
	u32 saved = bba_gap_us;
	int i, g, best = -1;
	for (g = 0; g < (int)(sizeof(gaps)/sizeof(gaps[0])); g++) {
		int bad = 0;
		bba_gap_us = gaps[g];
		for (i = 0; i < 30; i++)
			if (bba_r8(REG_NWAYS) != NWAYS_LINKUP) bad++;
		if (!bad) { best = (int)gaps[g]; break; }
	}
	bba_gap_us = saved;
	if (best < 0) {
		snprintf(m, n, "no gap up to 32us gave clean reads at speed idx %u",
		         (unsigned)bba_speed);
		return 1;
	}
	snprintf(m, n, "min clean header->data gap = %d us at speed idx %u",
	         best, (unsigned)bba_speed);
	return 0;
}

static int t_raw_sweep(char *m, size_t n)
{
	/* The SAME 8-slot read at EVERY speed index, reported as the first two
	 * bytes per index.  This is the measurement that distinguishes the two
	 * remaining explanations for a one-bit MISO lag:
	 *   - a shift that APPEARS or GROWS with clock rate is a timing problem;
	 *   - a shift that is constant across indices is structural.
	 * Run it against a PHASE_METER bitstream and every byte should read 80
	 * (aligned) / 40 (one bit late) / 20 (two bits late), with the register
	 * file and both byte FIFOs out of the path entirely. */
	u32 saved = bba_speed, s;
	int off = 0, bad = 0;
	m[0] = 0;
	for (s = 0; s <= EXI_SPEED32MHZ; s++) {
		u8 b[8];
		bba_speed = s;
		if (bba_read(REG_NWAYS, b, sizeof(b)) < 0) {
			off += snprintf(m + off, n - off, "%u:ERR ", (unsigned)s);
			bad++;
			continue;
		}
		off += snprintf(m + off, n - off, "%u:%02X%02X ",
		                (unsigned)s, b[0], b[1]);
		if (b[0] != NWAYS_LINKUP)
			bad++;
	}
	bba_speed = saved;
	return bad ? 1 : 0;
}

static int t_raw_reg(char *m, size_t n)
{
	/* Clock EIGHT data bytes for a one-byte register read and show them all.
	 * A correct device puts NWAYS (0x17) in slot 0.  If it shows up later the
	 * reply is merely LATE and the slot index gives the latency directly; if
	 * it never appears the decode is wrong, not slow. */
	u8 b[8];
	int i, at = -1;
	if (bba_read(REG_NWAYS, b, sizeof(b)) < 0) { snprintf(m, n, "EXI error"); return 1; }
	for (i = 0; i < 8; i++) if (b[i] == NWAYS_LINKUP) { at = i; break; }
	snprintf(m, n, "%02X %02X %02X %02X %02X %02X %02X %02X | 0x17 %s%d",
	         b[0],b[1],b[2],b[3],b[4],b[5],b[6],b[7],
	         at < 0 ? "absent" : "at slot ", at < 0 ? 0 : at);
	return at == 0 ? 0 : 1;
}

static int t_raw_id(char *m, size_t n)
{
	/* Same for the device ID: 2-byte header, then clock 8 instead of 4. */
	u8 b[8];
	int i, at = -1, rc;
	u16 h = 0x0000;
	/* Fast path for a reset this run issued.  Note this flag can be STALE
	 * (see iface_alive): it is clear after a netbooted update even though the
	 * FPGA's id_phase is long gone, which is why the result is also checked
	 * against iface_alive() below rather than trusted to this. */
	if (g_ncra_reset_done) {
		snprintf(m, n, "skipped: id_phase is a one-shot; reflash/reset the FPGA");
		return 2;
	}
	if ((rc = begin_raw()) < 0) { snprintf(m, n, "EXI error %d", rc); return 1; }
	EXI_Imm(BBA_EXI_CHAN, &h, 2, EXI_WRITE, NULL);
	EXI_Sync(BBA_EXI_CHAN);
	memset(b, 0, sizeof(b));
	EXI_ImmEx(BBA_EXI_CHAN, b, sizeof(b), EXI_READ);
	end_raw();
	for (i = 0; i < 8; i++) if (b[i] == 0x04) { at = i; break; }
	snprintf(m, n, "%02X %02X %02X %02X %02X %02X %02X %02X | 0x04 %s%d",
	         b[0],b[1],b[2],b[3],b[4],b[5],b[6],b[7],
	         at < 0 ? "absent" : "at slot ", at < 0 ? 0 : at);
	if (at == 0)
		return 0;
	/* Same discrimination as t_devid: a spent id_phase is not a fault. */
	return iface_alive() ? 2 : 1;
}

/* ───────────────────────── suite 5: ethernet ───────────────────────── */

static u8 g_mac[6] = {0x00,0x09,0xBF,0x00,0x00,0x01};
static const u8 SRC_IP[4] = {10,0,0,99};
static const u8 DST_IP[4] = {10,0,0,50};

static int t_mac_read(char *m, size_t n)
{
	u8 a[4], b[2];
	if (bba_read(REG_PAR0, a, 4) < 0 || bba_read(REG_PAR4, b, 2) < 0) {
		snprintf(m, n, "PAR read failed"); return 1;
	}
	memcpy(g_mac, a, 4); memcpy(g_mac + 4, b, 2);
	snprintf(m, n, "%02X:%02X:%02X:%02X:%02X:%02X",
	         g_mac[0],g_mac[1],g_mac[2],g_mac[3],g_mac[4],g_mac[5]);
	return (g_mac[0]==0x00 && g_mac[1]==0x09 && g_mac[2]==0xBF) ? 0 : 1;
}

static u32 build_arp(u8 *f)
{
	memset(f, 0, 60);
	memset(f, 0xFF, 6);                      /* dst: broadcast          */
	memcpy(f + 6, g_mac, 6);                 /* src MAC                 */
	f[12] = 0x08; f[13] = 0x06;              /* ethertype ARP           */
	f[14] = 0x00; f[15] = 0x01;              /* HTYPE ethernet          */
	f[16] = 0x08; f[17] = 0x00;              /* PTYPE IPv4              */
	f[18] = 6;    f[19] = 4;                 /* HLEN / PLEN             */
	f[20] = 0x00; f[21] = 0x01;              /* OPER request            */
	memcpy(f + 22, g_mac, 6);                /* SHA                     */
	memcpy(f + 28, SRC_IP, 4);               /* SPA                     */
	memcpy(f + 38, DST_IP, 4);               /* TPA (THA stays zero)    */
	return 60;
}

static int t_tx(char *m, size_t n)
{
	u8 f[60];
	u32 len = build_arp(f);
	int i, ir = 0;

	bba_w8(REG_IR, 0xFF);                                  /* clear IR     */
	bba_w8(REG_TWD_LO, (u8)(len & 0xFF));                  /* frame length */
	bba_w8(REG_TWD_HI, (u8)((len >> 8) & 0xFF));
	if (bba_tx_bytes(f, len) < 0) { snprintf(m, n, "TXDATA stream failed"); return 1; }
	bba_w8(REG_NCRA, NCRA_SR | NCRA_ST0);                  /* fire          */

	for (i = 0; i < 60; i++) {
		ir = bba_r8(REG_IR);
		if (ir >= 0 && (ir & IR_TI)) {
			snprintf(m, n, "%u-byte ARP sent, TI set after %d poll(s)", (unsigned)len, i);
			return 0;
		}
		msleep(10);
	}
	/* TI only means TXFrameDrain handed the frame to the W5100 -- it is NOT
	 * proof the chip put it on the wire.  Absence of TI is still a clear
	 * failure though. */
	snprintf(m, n, "TI never set (IR=0x%02X) - W5100 may be wedged", ir);
	return 1;
}

static int t_rx(char *m, size_t n)
{
	u8 r0[2], r1[2];
	int i, ir;
	if (bba_read(REG_RWP_LO, r0, 2) < 0) { snprintf(m, n, "RWP read failed"); return 1; }
	/* Catch RRP up to RWP before waiting, i.e. declare everything already in
	 * the ring consumed -- which is what a real driver does once it has read
	 * the frames out, and what netboot does at start-up.
	 *
	 * ⚠️ Without this the test fails on a HEALTHY adapter.  This app never
	 * writes RRP, so ambient broadcast traffic fills the 15-page ring, `free`
	 * falls below _MAX_FRAME_PAGES (6) and RBFI then drops EVERY frame --
	 * correctly, to avoid lapping.  RWP stops advancing permanently and this
	 * test reports "no frame in 2 s (RWP still 0x000F)" for the rest of the
	 * session.  Page 15 is the giveaway: free = (1 + 15 - 15) mod 15 = 1.
	 *
	 * Freeing the ring here also leaves exactly the newly received frame
	 * unconsumed at RRP, which is where the SPRAM/DMA suite reads. */
	if (bba_w8(REG_RRP_LO, r0[0]) < 0) {
		snprintf(m, n, "RRP write failed"); return 1;
	}
	for (i = 0; i < 200; i++) {                 /* up to ~2 s */
		if (bba_read(REG_RWP_LO, r1, 2) < 0) { snprintf(m, n, "RWP read failed"); return 1; }
		ir = bba_r8(REG_IR);
		if (memcmp(r0, r1, 2) != 0 || (ir >= 0 && (ir & IR_RI))) {
			snprintf(m, n, "RWP 0x%02X%02X -> 0x%02X%02X, RI=%d",
			         r0[1], r0[0], r1[1], r1[0], (ir & IR_RI) ? 1 : 0);
			return 0;
		}
		msleep(10);
	}
	snprintf(m, n, "no frame in 2 s (RWP still 0x%02X%02X)", r0[1], r0[0]);
	return 1;
}

/* ─────────────────── suite 7: libogc init sequence ─────────────────── */
/* These replay what libogc's own BBA driver does, in its real transaction
 * shapes, rather than what our docs said it does.  The whole sequence was
 * read out of /opt/devkitpro/libogc/lib/cube/libbba.a (gcif.o, __bba_init) --
 * see CLAUDE.md.  Two of the mismatches it exposed were silent:
 *   - command space is a 2-byte header + data phase, not a 4-byte transfer,
 *     so every command-space write was being dropped; and
 *   - libogc READS the MAC out of PAR0-5 rather than writing it. */

static int t_cmd_write(char *m, size_t n)
{
	int rc, rb;
	/* Command register 2 is libogc's interrupt mask: it writes 0x00
	 * (IRMASKALL) at the start of init and 0xF8 (IRMASKNONE) at the end. */
	if ((rc = bba_cmd_write(0x02, 0xF8)) < 0) {
		snprintf(m, n, "cmd write failed: EXI error %d", rc); return 1;
	}
	if ((rb = bba_cmd_read(0x02)) < 0) {
		snprintf(m, n, "cmd read failed: EXI error %d", rb); return 1;
	}
	if (rb != 0xF8) {
		snprintf(m, n, "wrote 0xF8, read back 0x%02X "
		         "(2-byte cmd header not honoured?)", rb);
		return 1;
	}
	/* Put it back the way libogc leaves it at the start of init. */
	bba_cmd_write(0x02, 0x00);
	rb = bba_cmd_read(0x02);
	snprintf(m, n, "0xF8 then 0x00 read back (0x%02X)", rb);
	return rb == 0x00 ? 0 : 1;
}

static int t_mac_is_readable(char *m, size_t n)
{
	u8 mac[6];
	/* libogc does ONE 6-byte register read of 0x0020 and uses whatever it
	 * finds as the console's MAC -- it does not write one.  So PAR0-5 must
	 * hold a sane address out of reset, and a 6-byte read must work. */
	if (bba_read(REG_PAR0, mac, 6) < 0) {
		snprintf(m, n, "6-byte PAR read failed"); return 1;
	}
	snprintf(m, n, "%02X:%02X:%02X:%02X:%02X:%02X%s",
	         mac[0], mac[1], mac[2], mac[3], mac[4], mac[5],
	         (mac[0] == 0x00 && mac[1] == 0x09 && mac[2] == 0xBF)
	             ? " (Nintendo OUI)" : " - NOT a Nintendo OUI");
	if (mac[0] == 0xFF || (mac[0] | mac[1] | mac[2] | mac[3] | mac[4] | mac[5]) == 0)
		return 1;                       /* all-ones or all-zero is unusable */
	return (mac[0] == 0x00 && mac[1] == 0x09 && mac[2] == 0xBF) ? 0 : 1;
}

static int t_tx_no_twd(char *m, size_t n)
{
	u8 f[60];
	u32 len = build_arp(f);
	int i, ir = 0;

	/* libogc's __bba_link_tx writes NO TWD at all: read NWAYS, one
	 * register-space write of the whole frame to 0x0048, read NCRA, write
	 * NCRA = 0x04.  So the device must count the bytes it was handed.  The
	 * NCRA ST fallback used to queue the TWD value, which a driver that
	 * skips TWD never sets -- the frame went out with a stale or zero
	 * length.  Deliberately does NOT write TWD_LO/TWD_HI. */
	bba_w8(REG_IR, 0xFF);
	if (bba_tx_bytes(f, len) < 0) {
		snprintf(m, n, "TXDATA stream failed"); return 1;
	}
	bba_w8(REG_NCRA, NCRA_SR | NCRA_ST0);

	for (i = 0; i < 60; i++) {
		ir = bba_r8(REG_IR);
		if (ir >= 0 && (ir & IR_TI)) {
			snprintf(m, n, "%u B sent with NO TWD, TI after %d poll(s)",
			         (unsigned)len, i);
			return 0;
		}
		msleep(10);
	}
	snprintf(m, n, "TI never set (IR=0x%02X) without TWD", ir);
	return 1;
}

static int t_init_sequence(char *m, size_t n)
{
	/* The register writes libogc issues, in order, with the values it uses.
	 * Most are store-only (PHY/analog) and we ignore them; what matters is
	 * that none of them is misdecoded into something harmful -- the old
	 * guessed header format turned a NWAYS read into an NCRA reset, so this
	 * is a real risk, not a theoretical one. */
	static const struct { u16 a; u8 v; } seq[] = {
		{0x0060, 0x00},
		{0x0000, 0x01},                 /* NCRA reset  */
		{0x0000, 0x00},
		{0x0058, 0x80}, {0x0059, 0x00}, {0x005A, 0x03}, {0x005B, 0x83},
		{0x005C, 0x32}, {0x005D, 0xFE}, {0x005E, 0x1F}, {0x005F, 0x1F},
		{0x0001, 0x52}, {0x0060, 0x74},
		{0x0014, 0x00}, {0x0015, 0x06}, {0x0050, 0x80},
		{0x000C, 0x00}, {0x000D, 0x00}, {0x000A, 0x01}, {0x000B, 0x00},
		{0x001A, 0x0F}, {0x001B, 0x00}, /* RHBP = page 15 */
		{0x0016, 0x01}, {0x0017, 0x00}, /* RWP  = page 1  */
		{0x0018, 0x01}, {0x0019, 0x00}, /* RRP  = page 1  */
		{0x0032, 0x08},
		{0x0000, 0x08},                 /* NCRA SR: start receive */
		{0x0009, 0xFF},                 /* IR: clear all          */
		{0x0008, 0xDF},                 /* IMR (NOT 0x86)         */
	};
	unsigned i;
	int v;
	for (i = 0; i < sizeof(seq) / sizeof(seq[0]); i++) {
		if (bba_w8(seq[i].a, seq[i].v) < 0) {
			snprintf(m, n, "write %u (0x%04X=0x%02X) failed",
			         i, seq[i].a, seq[i].v);
			return 1;
		}
	}
	g_ncra_reset_done = 1;
	/* The sentinels must still read correctly afterwards -- if any write in
	 * that list had been misdecoded, the most likely casualty is the state
	 * these two report. */
	if ((v = bba_r8(REG_NWAYS)) != NWAYS_LINKUP) {
		snprintf(m, n, "NWAYS 0x%02X after init (want 0x%02X)",
		         v, NWAYS_LINKUP);
		return 1;
	}
	if ((v = bba_r8(REG_HIPR)) != HIPR_PRESENT) {
		snprintf(m, n, "HIPR 0x%02X after init (want 0x%02X)",
		         v, HIPR_PRESENT);
		return 1;
	}
	v = bba_r8(REG_NCRA);
	snprintf(m, n, "%u writes replayed; NCRA=0x%02X NWAYS/HIPR ok",
	         (unsigned)(sizeof(seq) / sizeof(seq[0])), v);
	return (v & 0x08) ? 0 : 1;          /* SR must still be set */
}

/* ─────────────────────── suite 6: SPRAM / DMA ──────────────────────── */

static int t_dma(char *m, size_t n)
{
	u8 buf[64], rp[2], wp[2];
	u32 dlen, page, addr, desc, nextp;
	if (bba_read(REG_RRP_LO, rp, 2) < 0) { snprintf(m, n, "RRP read failed"); return 1; }
	if (bba_read(REG_RWP_LO, wp, 2) < 0) { snprintf(m, n, "RWP read failed"); return 1; }
	page = ((u32)rp[1] << 8) | rp[0];
	/* RWP/RRP are PAGE pointers into the 15-page ring, so the next
	 * unconsumed frame's descriptor is at RRP*256 -- NOT at SPRAM_BASE.
	 * Reading 0x100 unconditionally only happens to work while nothing has
	 * been consumed and the ring has not wrapped, which is why this test
	 * reported "ring empty?" on a board that had just passed the RX test. */
	if (rp[0] == wp[0] && rp[1] == wp[1]) {
		snprintf(m, n, "ring empty: RRP==RWP==%u (send it a frame first)",
		         (unsigned)page);
		return 2;
	}
	if (page < 1 || page > 15) {
		snprintf(m, n, "RRP page %u outside ring pages 1-15", (unsigned)page);
		return 1;
	}
	addr = page << 8;
	if (bba_stream((u16)addr, buf, sizeof(buf)) < 0) {
		snprintf(m, n, "stream read at 0x%04X failed", (unsigned)addr);
		return 1;
	}
	/* The 4-byte ring descriptor is a PACKED 32-BIT LITTLE-ENDIAN WORD, the
	 * format libogc's own driver reads:
	 *   bits 0-11 next_packet_ptr (page), 12-23 packet_len (INCLUDING these
	 *   4 bytes), 24-31 status (0x80 and 0x04 are errors).
	 * Decoded here exactly as bba_interrupt does. */
	desc  = (u32)buf[0] | ((u32)buf[1] << 8) |
	        ((u32)buf[2] << 16) | ((u32)buf[3] << 24);
	dlen  = (desc >> 12) & 0xFFF;
	nextp = desc & 0xFFF;
	if (((desc >> 24) & 0x84) == 0 && dlen > 4 && dlen <= 1518 + 4) {
		snprintf(m, n, "p%u len %u B, next p%u, etype %02X%02X",
		         (unsigned)page, (unsigned)(dlen - 4), (unsigned)nextp,
		         buf[16], buf[17]);
		return 0;
	}
	/* Diagnostic: the length alone does not say WHERE the frames are.  Walk
	 * all 15 ring pages and classify each descriptor, so one run shows
	 * whether the ring is empty, written at a different page than RRP says,
	 * or holding genuinely malformed descriptors:
	 *   '-' all-zero (never written)   'o' plausible frame length
	 *   'x' non-zero but implausible   '?' read failed
	 * Plus the raw 4 descriptor bytes at the RRP page. */
	{
		char map[16];
		u32 pg;
		u8 d[4];
		for (pg = 1; pg <= 15; pg++) {
			u32 dl;
			if (bba_stream((u16)(pg << 8), d, 4) < 0) {
				map[pg - 1] = '?';
				continue;
			}
			u32 w = (u32)d[0] | ((u32)d[1] << 8) |
			        ((u32)d[2] << 16) | ((u32)d[3] << 24);
			dl = (w >> 12) & 0xFFF;
			if (w == 0)                                      map[pg - 1] = '-';
			else if (((w >> 24) & 0x84) == 0 &&
			         dl > 4 && dl <= 1518 + 4)               map[pg - 1] = 'o';
			else                                             map[pg - 1] = 'x';
		}
		map[15] = 0;
		snprintf(m, n, "p%u len 0x%04X raw %02X %02X %02X %02X RWP=%u map %s",
		         (unsigned)page, (unsigned)dlen,
		         buf[0], buf[1], buf[2], buf[3],
		         (unsigned)(((u32)wp[1] << 8) | wp[0]), map);
	}
	return 1;
}

static int t_dma_stream_len(char *m, size_t n)
{
	u8 a[16], b[48];
	if (bba_stream(SPRAM_BASE, a, sizeof(a)) < 0 ||
	    bba_stream(SPRAM_BASE, b, sizeof(b)) < 0) {
		snprintf(m, n, "stream read failed"); return 1;
	}
	/* Reads >= 0x100 stream until CS, so the same address must give the same
	 * leading bytes regardless of how many we clock. */
	if (memcmp(a, b, sizeof(a)) != 0) {
		snprintf(m, n, "16B and 48B reads disagree - streaming is length-sensitive");
		return 1;
	}
	snprintf(m, n, "16B and 48B reads agree; streams until CS as designed");
	return 0;
}

/* ───────────────────────────── registry ────────────────────────────── */

static test_t s_identity[] = {
	{"Device ID",    "EXI link + enumeration: addr 0 returns 04 02 02 00", t_devid, T_PENDING, {0}},
	{"HIPR",         "BBA-present sentinel reads 0x01",                    t_hipr,  T_PENDING, {0}},
	{"NWAYS",        "link-status sentinel reads 0x17",                    t_nways, T_PENDING, {0}},
};
static test_t s_regs[] = {
	{"PAR0-3 w/r",   "MAC low bytes are writable and read back",           t_par_lo, T_PENDING, {0}},
	{"PAR4-5 w/r",   "MAC high bytes are writable and read back",          t_par_hi, T_PENDING, {0}},
	{"IMR",          "interrupt mask is writable (GC init writes 0x86)",   t_imr,    T_PENDING, {0}},
	{"IR write-1-clr","interrupt flags clear on write-1",                  t_ir_w1c, T_PENDING, {0}},
};
static test_t s_reset[] = {
	{"NCRA reset",   "RESET bit self-clears; W5100 re-inits behind it",    t_ncra_reset, T_PENDING, {0}},
	{"NCRA SR",      "start-receive bit holds",                            t_ncra_sr,    T_PENDING, {0}},
};
static test_t s_exi[] = {
	{"200x read",    "no bit errors over 200 register reads",              t_repeat,      T_PENDING, {0}},
	{"Speed sweep",  "which EXI clock indices are reliable (0..5)",        t_speed_sweep, T_PENDING, {0}},
	{"Gap sweep",    "min header->data idle gap the device needs",         t_gap_sweep,   T_PENDING, {0}},
	{"Raw reg dump", "8 slots of a NWAYS read - WHERE does 0x17 land?",    t_raw_reg,     T_PENDING, {0}},
	{"Raw ID dump",  "8 slots of the device-ID query - where is 0x04?",    t_raw_id,      T_PENDING, {0}},
	{"Per-speed dump","first 2 slots at EVERY speed - does the shift move?",t_raw_sweep,   T_PENDING, {0}},
};
static test_t s_eth[] = {
	{"MAC readback", "PAR0-5 hold a Nintendo-OUI MAC",                     t_mac_read, T_PENDING, {0}},
	{"TX ARP",       "60-byte frame reaches the W5100 and TI fires",       t_tx,       T_PENDING, {0}},
	{"RX frame",     "a frame arrives and RWP/RI advance",                 t_rx,       T_PENDING, {0}},
};
static test_t s_spram[] = {
	{"DMA descriptor","ring descriptor at 0x100 is well-formed",           t_dma,            T_PENDING, {0}},
	{"Stream length", "reads >= 0x100 stream until CS, length-independent",t_dma_stream_len, T_PENDING, {0}},
};

static test_t s_init[] = {
	{"cmd-space write","2-byte header + data phase, as libogc sends it",  t_cmd_write,       T_PENDING, {0}},
	{"MAC readable",  "libogc READS the MAC from PAR0-5; it must be sane", t_mac_is_readable, T_PENDING, {0}},
	{"init replay",   "libogc's 30 init writes, in order, do no harm",     t_init_sequence,   T_PENDING, {0}},
	{"TX without TWD","libogc never writes TWD; length must be counted",   t_tx_no_twd,       T_PENDING, {0}},
};

suite_t g_suites[] = {
	{"Identity",      "device enumerates and reports itself",      s_identity, 3},
	{"Registers",     "register file is readable and writable",    s_regs,     4},
	{"Reset/control", "NCRA reset and control bits behave",        s_reset,    2},
	{"EXI integrity", "the EXI link is error-free, and how fast",  s_exi,      6},
	{"Ethernet",      "frames get to and from the W5100",          s_eth,      3},
	{"SPRAM/DMA",     "bulk reads stream correctly from the ring", s_spram,    2},
	{"libogc init",   "the real driver's init sequence and shapes", s_init,     4},
};
const int g_nsuites = sizeof(g_suites) / sizeof(g_suites[0]);

void tests_run_test(test_t *t)
{
	int rc;
	t->msg[0] = 0;
	rc = t->run(t->msg, sizeof(t->msg));
	t->status = (rc == 0) ? T_PASS : (rc == 2 ? T_SKIP : T_FAIL);
}

void tests_run_suite(suite_t *s)
{
	int i;
	for (i = 0; i < s->ntests; i++) tests_run_test(&s->tests[i]);
}

void tests_run_all(void)
{
	int i;
	for (i = 0; i < g_nsuites; i++) tests_run_suite(&g_suites[i]);
}

void tests_reset_status(void)
{
	int i, j;
	for (i = 0; i < g_nsuites; i++)
		for (j = 0; j < g_suites[i].ntests; j++) {
			g_suites[i].tests[j].status = T_PENDING;
			g_suites[i].tests[j].msg[0] = 0;
		}
}

void tests_tally(int *pass, int *fail, int *skip, int *pending)
{
	int i, j;
	*pass = *fail = *skip = *pending = 0;
	for (i = 0; i < g_nsuites; i++)
		for (j = 0; j < g_suites[i].ntests; j++)
			switch (g_suites[i].tests[j].status) {
			case T_PASS: (*pass)++; break;
			case T_FAIL: (*fail)++; break;
			case T_SKIP: (*skip)++; break;
			default:     (*pending)++; break;
			}
}