avionic design with actual uboot and tooling

submodule of avionic design uboot bootloader and with included tools to
get you started , read readme.md and readme-tk1-loader.md

u-boot/arch/arm/mach-bcm283x/mbox.c

@@ -0,0 +1,165 @@
+/*
+ * (C) Copyright 2012 Stephen Warren
+ *
+ * SPDX-License-Identifier:	GPL-2.0+
+ */
+
+#include <common.h>
+#include <asm/io.h>
+#include <asm/arch/mbox.h>
+#include <phys2bus.h>
+
+#define TIMEOUT 1000 /* ms */
+
+int bcm2835_mbox_call_raw(u32 chan, u32 send, u32 *recv)
+{
+	struct bcm2835_mbox_regs *regs =
+		(struct bcm2835_mbox_regs *)BCM2835_MBOX_PHYSADDR;
+	ulong endtime = get_timer(0) + TIMEOUT;
+	u32 val;
+
+	debug("time: %lu timeout: %lu\n", get_timer(0), endtime);
+
+	if (send & BCM2835_CHAN_MASK) {
+		printf("mbox: Illegal mbox data 0x%08x\n", send);
+		return -1;
+	}
+
+	/* Drain any stale responses */
+
+	for (;;) {
+		val = readl(&regs->status);
+		if (val & BCM2835_MBOX_STATUS_RD_EMPTY)
+			break;
+		if (get_timer(0) >= endtime) {
+			printf("mbox: Timeout draining stale responses\n");
+			return -1;
+		}
+		val = readl(&regs->read);
+	}
+
+	/* Wait for space to send */
+
+	for (;;) {
+		val = readl(&regs->status);
+		if (!(val & BCM2835_MBOX_STATUS_WR_FULL))
+			break;
+		if (get_timer(0) >= endtime) {
+			printf("mbox: Timeout waiting for send space\n");
+			return -1;
+		}
+	}
+
+	/* Send the request */
+
+	val = BCM2835_MBOX_PACK(chan, send);
+	debug("mbox: TX raw: 0x%08x\n", val);
+	writel(val, &regs->write);
+
+	/* Wait for the response */
+
+	for (;;) {
+		val = readl(&regs->status);
+		if (!(val & BCM2835_MBOX_STATUS_RD_EMPTY))
+			break;
+		if (get_timer(0) >= endtime) {
+			printf("mbox: Timeout waiting for response\n");
+			return -1;
+		}
+	}
+
+	/* Read the response */
+
+	val = readl(&regs->read);
+	debug("mbox: RX raw: 0x%08x\n", val);
+
+	/* Validate the response */
+
+	if (BCM2835_MBOX_UNPACK_CHAN(val) != chan) {
+		printf("mbox: Response channel mismatch\n");
+		return -1;
+	}
+
+	*recv = BCM2835_MBOX_UNPACK_DATA(val);
+
+	return 0;
+}
+
+#ifdef DEBUG
+void dump_buf(struct bcm2835_mbox_hdr *buffer)
+{
+	u32 *p;
+	u32 words;
+	int i;
+
+	p = (u32 *)buffer;
+	words = buffer->buf_size / 4;
+	for (i = 0; i < words; i++)
+		printf("    0x%04x: 0x%08x\n", i * 4, p[i]);
+}
+#endif
+
+int bcm2835_mbox_call_prop(u32 chan, struct bcm2835_mbox_hdr *buffer)
+{
+	int ret;
+	u32 rbuffer;
+	struct bcm2835_mbox_tag_hdr *tag;
+	int tag_index;
+
+#ifdef DEBUG
+	printf("mbox: TX buffer\n");
+	dump_buf(buffer);
+#endif
+
+	flush_dcache_range((unsigned long)buffer,
+			   (unsigned long)((void *)buffer +
+			   roundup(buffer->buf_size, ARCH_DMA_MINALIGN)));
+
+	ret = bcm2835_mbox_call_raw(chan,
+				    phys_to_bus((unsigned long)buffer),
+				    &rbuffer);
+	if (ret)
+		return ret;
+
+	invalidate_dcache_range((unsigned long)buffer,
+				(unsigned long)((void *)buffer +
+				roundup(buffer->buf_size, ARCH_DMA_MINALIGN)));
+
+	if (rbuffer != phys_to_bus((unsigned long)buffer)) {
+		printf("mbox: Response buffer mismatch\n");
+		return -1;
+	}
+
+#ifdef DEBUG
+	printf("mbox: RX buffer\n");
+	dump_buf(buffer);
+#endif
+
+	/* Validate overall response status */
+
+	if (buffer->code != BCM2835_MBOX_RESP_CODE_SUCCESS) {
+		printf("mbox: Header response code invalid\n");
+		return -1;
+	}
+
+	/* Validate each tag's response status */
+
+	tag = (void *)(buffer + 1);
+	tag_index = 0;
+	while (tag->tag) {
+		if (!(tag->val_len & BCM2835_MBOX_TAG_VAL_LEN_RESPONSE)) {
+			printf("mbox: Tag %d missing val_len response bit\n",
+				tag_index);
+			return -1;
+		}
+		/*
+		 * Clear the reponse bit so clients can just look right at the
+		 * length field without extra processing
+		 */
+		tag->val_len &= ~BCM2835_MBOX_TAG_VAL_LEN_RESPONSE;
+		tag = (void *)(((u8 *)tag) + sizeof(*tag) + tag->val_buf_size);
+		tag_index++;
+	}
+
+	return 0;
+}