serial: Add serial_mvebu_a3700 for Armada 3700 SoC

The Armada 3700's UART is a simple serial port. It has a 32 bytes
Tx FIFO and a 64 bytes Rx FIFO integrated. This patch adds support
for this UART including the DEBUG UART functions for very early
debug output.

Signed-off-by: Stefan Roese <sr@denx.de>
Cc: Nadav Haklai <nadavh@marvell.com>
Cc: Kostya Porotchkin <kostap@marvell.com>
Cc: Wilson Ding <dingwei@marvell.com>
Cc: Victor Gu <xigu@marvell.com>
Cc: Hua Jing <jinghua@marvell.com>
Cc: Terry Zhou <bjzhou@marvell.com>
Cc: Hanna Hawa <hannah@marvell.com>
Cc: Haim Boot <hayim@marvell.com>

drivers/serial/Kconfig

@@ -147,6 +147,13 @@ config DEBUG_UART_ARM_DCC
 	  This port is available at least on ARMv6, ARMv7, ARMv8 and XScale
 	  architectures.
 
+config DEBUG_MVEBU_A3700_UART
+	bool "Marvell Armada 3700"
+	help
+	  Select this to enable a debug UART using the serial_mvebu 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_ZYNQ
 	bool "Xilinx Zynq"
 	help
@@ -295,6 +302,13 @@ config FSL_LPUART
 	  Select this to enable a Low Power UART for Freescale VF610 and
 	  QorIQ Layerscape devices.
 
+config MVEBU_A3700_UART
+	bool "UART support for Armada 3700"
+	default n
+	help
+	  Choose this option to add support for UART driver on the Marvell
+	  Armada 3700 SoC. The base address is configured via DT.
+
 config PIC32_SERIAL
 	bool "Support for Microchip PIC32 on-chip UART"
 	depends on DM_SERIAL && MACH_PIC32
@@ -371,4 +385,5 @@ config MSM_SERIAL
 	  It should support all Qualcomm devices with UARTDM version 1.4,
 	  for example APQ8016 and MSM8916.
 	  Single baudrate is supported in current implementation (115200).
+
 endmenu

drivers/serial/Makefile

@@ -46,6 +46,7 @@ obj-$(CONFIG_PIC32_SERIAL) += serial_pic32.o
 obj-$(CONFIG_STM32X7_SERIAL) += serial_stm32x7.o
 obj-$(CONFIG_BCM283X_MU_SERIAL) += serial_bcm283x_mu.o
 obj-$(CONFIG_MSM_SERIAL) += serial_msm.o
+obj-$(CONFIG_MVEBU_A3700_UART) += serial_mvebu_a3700.o
 
 ifndef CONFIG_SPL_BUILD
 obj-$(CONFIG_USB_TTY) += usbtty.o

drivers/serial/serial_mvebu_a3700.c

@@ -0,0 +1,175 @@
+/*
+ * Copyright (C) 2016 Stefan Roese <sr@denx.de>
+ *
+ * SPDX-License-Identifier:	GPL-2.0+
+ */
+
+#include <common.h>
+#include <dm.h>
+#include <serial.h>
+#include <asm/io.h>
+
+struct mvebu_platdata {
+	void __iomem *base;
+};
+
+/*
+ * Register offset
+ */
+#define UART_RX_REG		0x00
+#define UART_TX_REG		0x04
+#define UART_CTRL_REG		0x08
+#define UART_STATUS_REG		0x0c
+#define UART_BAUD_REG		0x10
+#define UART_POSSR_REG		0x14
+
+#define UART_STATUS_RX_RDY	0x10
+#define UART_STATUS_TXFIFO_FULL	0x800
+
+#define UART_CTRL_RXFIFO_RESET	0x4000
+#define UART_CTRL_TXFIFO_RESET	0x8000
+
+#define CONFIG_UART_BASE_CLOCK	25804800
+
+static int mvebu_serial_putc(struct udevice *dev, const char ch)
+{
+	struct mvebu_platdata *plat = dev_get_platdata(dev);
+	void __iomem *base = plat->base;
+
+	while (readl(base + UART_STATUS_REG) & UART_STATUS_TXFIFO_FULL)
+		;
+
+	writel(ch, base + UART_TX_REG);
+
+	return 0;
+}
+
+static int mvebu_serial_getc(struct udevice *dev)
+{
+	struct mvebu_platdata *plat = dev_get_platdata(dev);
+	void __iomem *base = plat->base;
+
+	while (!(readl(base + UART_STATUS_REG) & UART_STATUS_RX_RDY))
+		;
+
+	return readl(base + UART_RX_REG) & 0xff;
+}
+
+static int mvebu_serial_pending(struct udevice *dev, bool input)
+{
+	struct mvebu_platdata *plat = dev_get_platdata(dev);
+	void __iomem *base = plat->base;
+
+	if (readl(base + UART_STATUS_REG) & UART_STATUS_RX_RDY)
+		return 1;
+
+	return 0;
+}
+
+static int mvebu_serial_setbrg(struct udevice *dev, int baudrate)
+{
+	struct mvebu_platdata *plat = dev_get_platdata(dev);
+	void __iomem *base = plat->base;
+
+	/*
+	 * Calculate divider
+	 * baudrate = clock / 16 / divider
+	 */
+	writel(CONFIG_UART_BASE_CLOCK / baudrate / 16, base + UART_BAUD_REG);
+
+	/*
+	 * Set Programmable Oversampling Stack to 0,
+	 * UART defaults to 16x scheme
+	 */
+	writel(0, base + UART_POSSR_REG);
+
+	return 0;
+}
+
+static int mvebu_serial_probe(struct udevice *dev)
+{
+	struct mvebu_platdata *plat = dev_get_platdata(dev);
+	void __iomem *base = plat->base;
+
+	/* reset FIFOs */
+	writel(UART_CTRL_RXFIFO_RESET | UART_CTRL_TXFIFO_RESET,
+	       base + UART_CTRL_REG);
+
+	/* No Parity, 1 Stop */
+	writel(0, base + UART_CTRL_REG);
+
+	return 0;
+}
+
+static int mvebu_serial_ofdata_to_platdata(struct udevice *dev)
+{
+	struct mvebu_platdata *plat = dev_get_platdata(dev);
+
+	plat->base = dev_get_addr_ptr(dev);
+
+	return 0;
+}
+
+static const struct dm_serial_ops mvebu_serial_ops = {
+	.putc = mvebu_serial_putc,
+	.pending = mvebu_serial_pending,
+	.getc = mvebu_serial_getc,
+	.setbrg = mvebu_serial_setbrg,
+};
+
+static const struct udevice_id mvebu_serial_ids[] = {
+	{ .compatible = "marvell,armada-3700-uart" },
+	{ }
+};
+
+U_BOOT_DRIVER(serial_mvebu) = {
+	.name	= "serial_mvebu",
+	.id	= UCLASS_SERIAL,
+	.of_match = mvebu_serial_ids,
+	.ofdata_to_platdata = mvebu_serial_ofdata_to_platdata,
+	.platdata_auto_alloc_size = sizeof(struct mvebu_platdata),
+	.probe	= mvebu_serial_probe,
+	.ops	= &mvebu_serial_ops,
+	.flags	= DM_FLAG_PRE_RELOC,
+};
+
+#ifdef CONFIG_DEBUG_MVEBU_A3700_UART
+
+#include <debug_uart.h>
+
+static inline void _debug_uart_init(void)
+{
+	void __iomem *base = (void __iomem *)CONFIG_DEBUG_UART_BASE;
+
+	/* reset FIFOs */
+	writel(UART_CTRL_RXFIFO_RESET | UART_CTRL_TXFIFO_RESET,
+	       base + UART_CTRL_REG);
+
+	/* No Parity, 1 Stop */
+	writel(0, base + UART_CTRL_REG);
+
+	/*
+	 * Calculate divider
+	 * baudrate = clock / 16 / divider
+	 */
+	writel(CONFIG_UART_BASE_CLOCK / 115200 / 16, base + UART_BAUD_REG);
+
+	/*
+	 * Set Programmable Oversampling Stack to 0,
+	 * UART defaults to 16x scheme
+	 */
+	writel(0, base + UART_POSSR_REG);
+}
+
+static inline void _debug_uart_putc(int ch)
+{
+	void __iomem *base = (void __iomem *)CONFIG_DEBUG_UART_BASE;
+
+	while (readl(base + UART_STATUS_REG) & UART_STATUS_TXFIFO_FULL)
+		;
+
+	writel(ch, base + UART_TX_REG);
+}
+
+DEBUG_UART_FUNCS
+#endif