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>

4 files changed, 104 insertions, 0 deletions

diff --git a/board/sipeed/maix/Kconfig b/board/sipeed/maix/Kconfig
new file mode 100644
index 0000000000..0cdcd32adc
--- /dev/null
+++ b/board/sipeed/maix/Kconfig
@@ -0,0 +1,47 @@
+# SPDX-License-Identifier: GPL-2.0+
+# Copyright (C) 2019-20 Sean Anderson <seanga2@gmail.com>
+
+if TARGET_SIPEED_MAIX
+
+config SYS_BOARD
+	default "maix"
+
+config SYS_VENDOR
+	default "sipeed"
+
+config SYS_CPU
+	default "generic"
+
+config SYS_CONFIG_NAME
+	default "sipeed-maix"
+
+config SYS_TEXT_BASE
+	default 0x80000000
+
+config DEFAULT_DEVICE_TREE
+	default "k210-maix-bit"
+
+config NR_CPUS
+	default 2
+
+config NR_DRAM_BANKS
+	default 3
+
+config BOARD_SPECIFIC_OPTIONS
+	def_bool y
+	select GENERIC_RISCV
+	select RISCV_PRIV_1_9
+	imply SMP
+	imply DM_SERIAL
+	imply SIFIVE_SERIAL
+	imply SIFIVE_CLINT
+	imply POWER_DOMAIN
+	imply SIMPLE_PM_BUS
+	imply CLK_CCF
+	imply CLK_COMPOSITE_CCF
+	imply CLK_K210
+	imply DM_RESET
+	imply RESET_SYSCON
+	imply SYSRESET
+	imply SYSRESET_SYSCON
+endif
diff --git a/board/sipeed/maix/MAINTAINERS b/board/sipeed/maix/MAINTAINERS
new file mode 100644
index 0000000000..e7bb9ec433
--- /dev/null
+++ b/board/sipeed/maix/MAINTAINERS
@@ -0,0 +1,11 @@
+Sipeed Maix BOARD
+M:	Sean Anderson <seanga2@gmail.com>
+S:	Maintained
+F:	arch/riscv/dts/k210.dtsi
+F:	arch/riscv/dts/k210-maix-bit.dts
+F:	board/sipeed/maix/
+F:	configs/sipeed_maix_bitm_defconfig
+F:	doc/board/sipeed/
+F:	include/configs/sipeed-maix.h
+F:	include/dt-bindings/*/k210-sysctl.h
+F:	test/dm/k210_pll.c
diff --git a/board/sipeed/maix/Makefile b/board/sipeed/maix/Makefile
new file mode 100644
index 0000000000..4acff5b31e
--- /dev/null
+++ b/board/sipeed/maix/Makefile
@@ -0,0 +1,5 @@
+# SPDX-License-Identifier: GPL-2.0+
+#
+# Copyright (c) 2019 Western Digital Corporation or its affiliates.
+
+obj-y += maix.o
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;
+}