From 37a219b0b953591b6b9b603bc04611360f2677ef Mon Sep 17 00:00:00 2001
From: Werner Almesberger <werner@almesberger.net>
Date: Sat, 26 Jan 2013 23:25:17 -0300
Subject: [PATCH] ubb-la/ubb-la.c: option -n N to enter experimental
 multi-buffer mode (WIP)

---
 ubb-la/ubb-la.c | 107 ++++++++++++++++++++++++++++++++++++++++++++++--
 1 file changed, 104 insertions(+), 3 deletions(-)

diff --git a/ubb-la/ubb-la.c b/ubb-la/ubb-la.c
index 6dffde4..de62d4b 100644
--- a/ubb-la/ubb-la.c
+++ b/ubb-la/ubb-la.c
@@ -99,6 +99,7 @@ static void dma_setup(unsigned long buf, int nibbles)
 {
 	assert(!(nibbles & 63));
 
+/* need to reset DSA, DTA, DTC when done. uncertain about DCS */
 	DCS(DMA) = DCS_NDES;			/* no-descriptor transfer */
 	DSA(DMA) = REG_PADDR(MSC_RXFIFO);	/* source */
 	DTA(DMA) = buf;				/* destination */
@@ -166,6 +167,61 @@ quit:
 }
 
 
+static void xfers(unsigned long *bufs, int n_bufs, int nibbles)
+{
+	int i = 0;
+
+	dma_init();
+
+	MSC_STRPCL = MSC_STRPCRL_START_CLOCK;	/* start the bus clock */
+	MSC_RESTO = MSC_RESTO_MASK;		/* maximum response time-out */
+	MSC_RDTO = MSC_RDTO_MASK;
+	MSC_BLKLEN = nibbles >> 1;
+
+	MSC_CMDAT =
+	    MSC_CMDAT_BUS_WIDTH_4 << MSC_CMDAT_BUS_WIDTH_SHIFT |
+	    MSC_CMDAT_DMA_EN |		/* DMA */
+	    MSC_CMDAT_DATA_EN |		/* with data transfer */
+	    MSC_CMDAT_RESPONSE_FORMAT_NONE; /* no response required */
+
+	disable_interrupts();
+
+	OUT(UBB_CMD);
+	dma_setup(bufs[0], nibbles);
+
+	while (1) {
+		MSC_STRPCL = MSC_STRPCRL_START_OP;
+
+		while (MSC_STAT & MSC_STAT_DATA_FIFO_EMPTY);
+
+		IN(UBB_CMD);
+
+		DCS(DMA) =
+		    DCS_NDES |          /* no descriptor */
+		    DCS_CTE;            /* enable channel */
+
+		/*
+		 * @@@ We could enable interrupts while waiting, particularly
+		 * at low sample rates, as long as the probability of missing
+		 * the end of the DMA transfer is acceptably low.
+		 */
+		wait_dma_done();
+
+		if (++i == n_bufs)
+			break;
+
+		OUT(UBB_CMD);
+		dma_setup(bufs[i], nibbles);
+
+		while (!(MSC_STAT & MSC_STAT_DATA_TRAN_DONE));
+	}
+
+	enable_interrupts();
+
+	dma_cleanup();
+}
+
+
 static void print_samples(FILE *file, uint8_t *buf, int skip, int nibbles)
 {
 	uint8_t v, last = 0xff;
@@ -225,6 +281,38 @@ static int do_buf(int nibbles, uint32_t trigger, uint32_t mask)
 }
 
 
+static void do_bufs(int n_bufs, int nibbles)
+{
+	uint8_t *bufs[n_bufs];
+	struct physmem_vec vecs[n_bufs];
+	unsigned long addrs[n_bufs];
+	int i,n;
+
+	if (mlockall(MCL_CURRENT | MCL_FUTURE)) {
+		perror("mlockall");
+		exit(1);
+	}
+
+	for (i = 0; i != n_bufs; i++) {
+		bufs[i] = physmem_malloc(4096);
+		memset(bufs[i], 0, 4096);
+		physmem_flush(bufs[i], 4096);
+
+		n = physmem_xlat(bufs[i], nibbles >> 1, vecs+i, 1);
+		if (n != 1) {
+			fprintf(stderr,
+			    "physmem_xlat_vec: expected 1, got %d\n", n);
+			exit(1);
+		}
+		addrs[i] = vecs[i].addr;
+	}
+	xfers(addrs, n_bufs, nibbles);
+
+	for (i = 0; i != n_bufs; i++)
+		print_samples(stdout, bufs[i], INITIAL_SKIP, nibbles);
+}
+
+
 /* ----- Command-line processing ------------------------------------------- */
 
 
@@ -263,9 +351,11 @@ static unsigned long xlat_pins(unsigned long pins)
 static void usage(const char *name)
 {
 	fprintf(stderr,
-"usage: %s [-C] [-t pattern/mask] [-f frequency_MHz]\n\n"
+"usage: %s [-C] [-t pattern/mask] [-f frequency_MHz] [-n N]\n\n"
 "  -C               output the MMC clock on CLK/TRIG (for debugging)\n"
 "  -f freq_MHz      select the specified frequency (default; 1 MHz)\n"
+"  -n N             capture N buffers worth of samples without waiting for a\n"
+"                   trigger\n"
 "  -t pattern/mask  start capture at the specified pattern (DAT0 = 1, etc.,\n"
 "                   CLK = 16). Default: any change on TRIG.\n"
     , name);
@@ -277,12 +367,13 @@ int main(int argc, char **argv)
 {
 	double freq_mhz = 1;
 	unsigned long trigger = 1, mask = 0;
+	unsigned long multi = 0;
 	int clkout = 0;
 	struct mmcclk clk;
 	char *end;
 	int c, res;
 
-	while ((c = getopt(argc, argv, "Cf:t:")) != EOF)
+	while ((c = getopt(argc, argv, "Cf:n:t:")) != EOF)
 		switch (c) {
 		case 'C':
 			clkout = 1;
@@ -292,6 +383,11 @@ int main(int argc, char **argv)
 			if (*end)
 				usage(*argv);
 			break;
+		case 'n':
+			multi = strtoul(optarg, &end, 0);
+			if (*end)
+				usage(*argv);
+			break;
 		case 't':
 			trigger = strtoul(optarg, &end, 0);
 			if (*end != '/')
@@ -327,7 +423,12 @@ int main(int argc, char **argv)
 		mask = UBB_CLK;
 	}
 
-	res = !do_buf(8128, trigger, mask);
+	if (!multi) {
+		res = !do_buf(8128, trigger, mask);
+	} else {
+		do_bufs(multi, 8128);
+		res = 0;
+	}
 
 	mmcclk_stop();
 	ubb_close(UBB_ALL);