arm: add initial support for Amlogic Meson and ODROID-C2

This adds platform code for the Amlogic Meson GXBaby (S905) SoC and a
board definition for ODROID-C2. This initial submission only supports
UART and Ethernet (through the existing Designware driver). DTS files
are the ones submitted to Linux arm-soc for 4.7 [1].

[1] https://patchwork.ozlabs.org/patch/603583/

Signed-off-by: Beniamino Galvani <b.galvani@gmail.com>
Reviewed-by: Simon Glass <sjg@chromium.org>

drivers/serial/Kconfig

@@ -121,6 +121,14 @@ config DEBUG_UART_S5P
 	  will need to provide parameters to make this work. The driver will
 	  be available until the real driver-model serial is running.
 
+config DEBUG_UART_MESON
+	bool "Amlogic Meson"
+	depends on MESON_SERIAL
+	help
+	  Select this to enable a debug UART using the serial_meson driver. You
+	  will need to provide parameters to make this work. The driver will
+	  be available until the real driver-model serial is running.
+
 config DEBUG_UART_UARTLITE
 	bool "Xilinx Uartlite"
 	help
@@ -338,6 +346,13 @@ config XILINX_UARTLITE
 	  If you have a Xilinx based board and want to use the uartlite
 	  serial ports, say Y to this option. If unsure, say N.
 
+config MESON_SERIAL
+	bool "Support for Amlogic Meson UART"
+	depends on DM_SERIAL && ARCH_MESON
+	help
+	  If you have an Amlogic Meson based board and want to use the on-chip
+	  serial ports, say Y to this option. If unsure, say N.
+
 config MSM_SERIAL
 	bool "Qualcomm on-chip UART"
 	depends on DM_SERIAL

drivers/serial/Makefile

@@ -27,6 +27,7 @@ obj-$(CONFIG_SYS_NS16550) += ns16550.o
 obj-$(CONFIG_S5P) += serial_s5p.o
 obj-$(CONFIG_MXC_UART) += serial_mxc.o
 obj-$(CONFIG_PXA_SERIAL) += serial_pxa.o
+obj-$(CONFIG_MESON_SERIAL) += serial_meson.o
 obj-$(CONFIG_S3C24X0_SERIAL) += serial_s3c24x0.o
 obj-$(CONFIG_XILINX_UARTLITE) += serial_xuartlite.o
 obj-$(CONFIG_SANDBOX_SERIAL) += sandbox.o

drivers/serial/serial_meson.c

@@ -0,0 +1,162 @@
+/*
+ * (C) Copyright 2016 Beniamino Galvani <b.galvani@gmail.com>
+ *
+ * SPDX-License-Identifier:	GPL-2.0+
+ */
+
+#include <common.h>
+#include <dm.h>
+#include <errno.h>
+#include <fdtdec.h>
+#include <linux/compiler.h>
+#include <serial.h>
+
+DECLARE_GLOBAL_DATA_PTR;
+
+struct meson_uart {
+	u32 wfifo;
+	u32 rfifo;
+	u32 control;
+	u32 status;
+	u32 misc;
+};
+
+struct meson_serial_platdata {
+	struct meson_uart *reg;
+};
+
+/* AML_UART_STATUS bits */
+#define AML_UART_PARITY_ERR		BIT(16)
+#define AML_UART_FRAME_ERR		BIT(17)
+#define AML_UART_TX_FIFO_WERR		BIT(18)
+#define AML_UART_RX_EMPTY		BIT(20)
+#define AML_UART_TX_FULL		BIT(21)
+#define AML_UART_TX_EMPTY		BIT(22)
+#define AML_UART_XMIT_BUSY		BIT(25)
+#define AML_UART_ERR			(AML_UART_PARITY_ERR | \
+					 AML_UART_FRAME_ERR  | \
+					 AML_UART_TX_FIFO_WERR)
+
+/* AML_UART_CONTROL bits */
+#define AML_UART_TX_EN			BIT(12)
+#define AML_UART_RX_EN			BIT(13)
+#define AML_UART_TX_RST			BIT(22)
+#define AML_UART_RX_RST			BIT(23)
+#define AML_UART_CLR_ERR		BIT(24)
+
+static void meson_serial_init(struct meson_uart *uart)
+{
+	u32 val;
+
+	val = readl(&uart->control);
+	val |= (AML_UART_RX_RST | AML_UART_TX_RST | AML_UART_CLR_ERR);
+	writel(val, &uart->control);
+	val &= ~(AML_UART_RX_RST | AML_UART_TX_RST | AML_UART_CLR_ERR);
+	writel(val, &uart->control);
+	val |= (AML_UART_RX_EN | AML_UART_TX_EN);
+	writel(val, &uart->control);
+}
+
+static int meson_serial_probe(struct udevice *dev)
+{
+	struct meson_serial_platdata *plat = dev->platdata;
+	struct meson_uart *const uart = plat->reg;
+
+	meson_serial_init(uart);
+
+	return 0;
+}
+
+static int meson_serial_getc(struct udevice *dev)
+{
+	struct meson_serial_platdata *plat = dev->platdata;
+	struct meson_uart *const uart = plat->reg;
+
+	if (readl(&uart->status) & AML_UART_RX_EMPTY)
+		return -EAGAIN;
+
+	return readl(&uart->rfifo) & 0xff;
+}
+
+static int meson_serial_putc(struct udevice *dev, const char ch)
+{
+	struct meson_serial_platdata *plat = dev->platdata;
+	struct meson_uart *const uart = plat->reg;
+
+	if (readl(&uart->status) & AML_UART_TX_FULL)
+		return -EAGAIN;
+
+	writel(ch, &uart->wfifo);
+
+	return 0;
+}
+
+static int meson_serial_pending(struct udevice *dev, bool input)
+{
+	struct meson_serial_platdata *plat = dev->platdata;
+	struct meson_uart *const uart = plat->reg;
+	uint32_t status = readl(&uart->status);
+
+	if (input)
+		return !(status & AML_UART_RX_EMPTY);
+	else
+		return !(status & AML_UART_TX_FULL);
+}
+
+static int meson_serial_ofdata_to_platdata(struct udevice *dev)
+{
+	struct meson_serial_platdata *plat = dev->platdata;
+	fdt_addr_t addr;
+
+	addr = dev_get_addr(dev);
+	if (addr == FDT_ADDR_T_NONE)
+		return -EINVAL;
+
+	plat->reg = (struct meson_uart *)addr;
+
+	return 0;
+}
+
+static const struct dm_serial_ops meson_serial_ops = {
+	.putc = meson_serial_putc,
+	.pending = meson_serial_pending,
+	.getc = meson_serial_getc,
+};
+
+static const struct udevice_id meson_serial_ids[] = {
+	{ .compatible = "amlogic,meson-uart" },
+	{ }
+};
+
+U_BOOT_DRIVER(serial_meson) = {
+	.name		= "serial_meson",
+	.id		= UCLASS_SERIAL,
+	.of_match	= meson_serial_ids,
+	.probe		= meson_serial_probe,
+	.ops		= &meson_serial_ops,
+	.flags		= DM_FLAG_PRE_RELOC,
+	.ofdata_to_platdata = meson_serial_ofdata_to_platdata,
+	.platdata_auto_alloc_size = sizeof(struct meson_serial_platdata),
+};
+
+#ifdef CONFIG_DEBUG_UART_MESON
+
+#include <debug_uart.h>
+
+static inline void _debug_uart_init(void)
+{
+}
+
+static inline void _debug_uart_putc(int ch)
+{
+	struct meson_uart *regs = (struct meson_uart *)CONFIG_DEBUG_UART_BASE;
+
+	while (readl(&regs->status) & AML_UART_TX_FULL)
+		;
+
+	writel(ch, &regs->wfifo);
+}
+
+DEBUG_UART_FUNCS
+
+#endif