ARM: mxs: Added application UART driver

The driver makes it possible to use an application UART as
the U-Boot output console for Freescale i.MX23/i.MX28 devices.

Signed-off-by: Andreas Wass <andreas.wass@dalelven.com>
Cc: Fabio Estevam <fabio.estevam@freescale.com>
Cc: Marek Vasut <marex@denx.de>
Acked-by: Marek Vasut <marex@denx.de>

3 files changed, 154 insertions, 0 deletions

diff --git a/drivers/serial/Makefile b/drivers/serial/Makefile
index 697f2bb..4c45bfa 100644
--- a/drivers/serial/Makefile
+++ b/drivers/serial/Makefile
@@ -38,6 +38,7 @@ COBJS-$(CONFIG_SCIF_CONSOLE) += serial_sh.o
 COBJS-$(CONFIG_ZYNQ_SERIAL) += serial_zynq.o
 COBJS-$(CONFIG_BFIN_SERIAL) += serial_bfin.o
 COBJS-$(CONFIG_FSL_LPUART) += serial_lpuart.o
+COBJS-$(CONFIG_MXS_AUART) += mxs_auart.o
 
 ifndef CONFIG_SPL_BUILD
 COBJS-$(CONFIG_USB_TTY) += usbtty.o
diff --git a/drivers/serial/mxs_auart.c b/drivers/serial/mxs_auart.c
new file mode 100644
index 0000000..7cfe5bc
--- /dev/null
+++ b/drivers/serial/mxs_auart.c
@@ -0,0 +1,151 @@
+/*
+ * Freescale i.MX23/i.MX28 AUART driver
+ *
+ * Copyright (C) 2013 Andreas Wass <andreas.wass@dalelven.com>
+ *
+ * Based on the MXC serial driver:
+ *
+ * (c) 2007 Sascha Hauer <s.hauer@pengutronix.de>
+ *
+ * Further based on the Linux mxs-auart.c driver:
+ *
+ * Freescale STMP37XX/STMP38X Application UART drkiver
+ * Copyright 2008-2010 Freescale Semiconductor, Inc.
+ *
+ * SPDX-License-Identifier:	GPL-2.0+
+ */
+#include <common.h>
+#include <asm/io.h>
+#include <serial.h>
+#include <linux/compiler.h>
+#include <asm/arch/regs-base.h>
+#include <asm/arch/regs-uartapp.h>
+#include <asm/arch/sys_proto.h>
+
+DECLARE_GLOBAL_DATA_PTR;
+
+#ifndef CONFIG_MXS_AUART_BASE
+#error "CONFIG_MXS_AUART_BASE must be set to the base UART to use"
+#endif
+
+/* AUART clock always supplied by XTAL and always 24MHz */
+#define MXS_AUART_CLK 24000000
+
+static struct mxs_uartapp_regs *get_uartapp_registers(void)
+{
+	return (struct mxs_uartapp_regs *)CONFIG_MXS_AUART_BASE;
+}
+
+/**
+ * Sets the baud rate and settings.
+ * The settings are: 8 data bits, no parit and 1 stop bit.
+ */
+void mxs_auart_setbrg(void)
+{
+	u32 div;
+	u32 linectrl = 0;
+	struct mxs_uartapp_regs *regs = get_uartapp_registers();
+
+	if (!gd->baudrate)
+		gd->baudrate = CONFIG_BAUDRATE;
+
+	/*
+	 * From i.MX28 datasheet:
+	 * div is calculated by calculating UARTCLK*32/baudrate, rounded to int
+	 * div must be between 0xEC and 0x003FFFC0 inclusive
+	 * Lowest 6 bits of div goes in BAUD_DIVFRAC part of LINECTRL register
+	 * Next 16 bits goes in BAUD_DIVINT part of LINECTRL register
+	 */
+	div = (MXS_AUART_CLK * 32) / gd->baudrate;
+	if (div < 0xEC || div > 0x003FFFC0)
+		return;
+
+	linectrl |= ((div & UARTAPP_LINECTRL_EXTRACT_BAUD_DIVFRAC_MASK) <<
+		UARTAPP_LINECTRL_BAUD_DIVFRAC_OFFSET) &
+		UARTAPP_LINECTRL_BAUD_DIVFRAC_MASK;
+	linectrl |= ((div >> UARTAPP_LINECTRL_EXTRACT_BAUD_DIVINT_OFFSET) <<
+		UARTAPP_LINECTRL_BAUD_DIVINT_OFFSET) &
+		UARTAPP_LINECTRL_BAUD_DIVINT_MASK;
+
+	/* Word length: 8 bits */
+	linectrl |= UARTAPP_LINECTRL_WLEN_8BITS;
+
+	/* Enable FIFOs. */
+	linectrl |= UARTAPP_LINECTRL_FEN_MASK;
+
+	/* Write above settings, no parity, 1 stop bit */
+	writel(linectrl, &regs->hw_uartapp_linectrl);
+}
+
+int mxs_auart_init(void)
+{
+	struct mxs_uartapp_regs *regs = get_uartapp_registers();
+	/* Reset everything */
+	mxs_reset_block(&regs->hw_uartapp_ctrl0_reg);
+	/* Disable interrupts */
+	writel(0, &regs->hw_uartapp_intr);
+	/* Set baud rate and settings */
+	serial_setbrg();
+	/* Disable RTS and CTS, ignore LINECTRL2 register */
+	writel(UARTAPP_CTRL2_RTSEN_MASK |
+			UARTAPP_CTRL2_CTSEN_MASK |
+			UARTAPP_CTRL2_USE_LCR2_MASK,
+			&regs->hw_uartapp_ctrl2_clr);
+	/* Enable receiver, transmitter and UART */
+	writel(UARTAPP_CTRL2_RXE_MASK |
+			UARTAPP_CTRL2_TXE_MASK |
+			UARTAPP_CTRL2_UARTEN_MASK,
+			&regs->hw_uartapp_ctrl2_set);
+	return 0;
+}
+
+void mxs_auart_putc(const char c)
+{
+	struct mxs_uartapp_regs *regs = get_uartapp_registers();
+	/* Wait in loop while the transmit FIFO is full */
+	while (readl(&regs->hw_uartapp_stat) & UARTAPP_STAT_TXFF_MASK)
+		;
+
+	writel(c, &regs->hw_uartapp_data);
+
+	if (c == '\n')
+		mxs_auart_putc('\r');
+}
+
+int mxs_auart_tstc(void)
+{
+	struct mxs_uartapp_regs *regs = get_uartapp_registers();
+	/* Checks if receive FIFO is empty */
+	return !(readl(&regs->hw_uartapp_stat) & UARTAPP_STAT_RXFE_MASK);
+}
+
+int mxs_auart_getc(void)
+{
+	struct mxs_uartapp_regs *regs = get_uartapp_registers();
+	/* Wait until a character is available to read */
+	while (!mxs_auart_tstc())
+		;
+	/* Read the character from the data register */
+	return readl(&regs->hw_uartapp_data) & 0xFF;
+}
+
+static struct serial_device mxs_auart_drv = {
+	.name = "mxs_auart_serial",
+	.start = mxs_auart_init,
+	.stop = NULL,
+	.setbrg = mxs_auart_setbrg,
+	.putc = mxs_auart_putc,
+	.puts = default_serial_puts,
+	.getc = mxs_auart_getc,
+	.tstc = mxs_auart_tstc,
+};
+
+void mxs_auart_initialize(void)
+{
+	serial_register(&mxs_auart_drv);
+}
+
+__weak struct serial_device *default_serial_console(void)
+{
+	return &mxs_auart_drv;
+}
diff --git a/drivers/serial/serial.c b/drivers/serial/serial.c
index 6730135..336ff35 100644
--- a/drivers/serial/serial.c
+++ b/drivers/serial/serial.c
@@ -159,6 +159,7 @@ serial_initfunc(pl01x_serial_initialize);
 serial_initfunc(s3c44b0_serial_initialize);
 serial_initfunc(sa1100_serial_initialize);
 serial_initfunc(sh_serial_initialize);
+serial_initfunc(mxs_auart_initialize);
 
 /**
  * serial_register() - Register serial driver with serial driver core
@@ -251,6 +252,7 @@ void serial_initialize(void)
 	s3c44b0_serial_initialize();
 	sa1100_serial_initialize();
 	sh_serial_initialize();
+	mxs_auart_initialize();
 
 	serial_assign(default_serial_console()->name);
 }