riscv: Add Sipeed Maix support

The Sipeed Maix series is a collection of boards built around the RISC-V
Kendryte K210 processor. This processor contains several peripherals to
accelerate neural network processing and other "ai" tasks. This includes a
"KPU" neural network processor, an audio processor supporting beamforming
reception, and a digital video port supporting capture and output at VGA
resolution. Other peripherals include 8M of sram (accessible with and
without caching); remappable pins, including 40 GPIOs; AES, FFT, and SHA256
accelerators; a DMA controller; and I2C, I2S, and SPI controllers. Maix
peripherals vary, but include spi flash; on-board usb-serial bridges; ports
for cameras, displays, and sd cards; and ESP32 chips. Currently, only the
Sipeed Maix Bit V2.0 (bitm) is supported, but the boards are fairly
similar.

Documentation for Maix boards is located at
<http://dl.sipeed.com/MAIX/HDK/>.  Documentation for the Kendryte K210 is
located at <https://kendryte.com/downloads/>. However, hardware details are
rather lacking, so most technical reference has been taken from the
standalone sdk located at
<https://github.com/kendryte/kendryte-standalone-sdk>.

Signed-off-by: Sean Anderson <seanga2@gmail.com>

1 files changed, 41 insertions, 0 deletions

diff --git a/board/sipeed/maix/maix.c b/board/sipeed/maix/maix.c
new file mode 100644
index 0000000000..cbcb23cf5c
--- /dev/null
+++ b/board/sipeed/maix/maix.c
@@ -0,0 +1,41 @@
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * Copyright (C) 2019-20 Sean Anderson <seanga2@gmail.com>
+ */
+
+#include <common.h>
+#include <clk.h>
+#include <dm.h>
+#include <fdt_support.h>
+#include <asm/io.h>
+
+phys_size_t get_effective_memsize(void)
+{
+	return CONFIG_SYS_SDRAM_SIZE;
+}
+
+int board_init(void)
+{
+	int ret, i;
+	const char * const banks[] = { "sram0", "sram1", "airam" };
+	ofnode memory;
+	struct clk clk;
+
+	/* Enable RAM clocks */
+	memory = ofnode_by_compatible(ofnode_null(), "kendryte,k210-sram");
+	if (ofnode_equal(memory, ofnode_null()))
+		return -ENOENT;
+
+	for (i = 0; i < ARRAY_SIZE(banks); i++) {
+		ret = clk_get_by_name_nodev(memory, banks[i], &clk);
+		if (ret)
+			continue;
+
+		ret = clk_enable(&clk);
+		clk_free(&clk);
+		if (ret)
+			return ret;
+	}
+
+	return 0;
+}