Adding upstream version 6.6.15.upstream/6.6.15

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 866 insertions, 0 deletions

diff --git a/drivers/tty/serial/meson_uart.c b/drivers/tty/serial/meson_uart.c
new file mode 100644
index 0000000000..9388b9ddea
--- /dev/null
+++ b/drivers/tty/serial/meson_uart.c
@@ -0,0 +1,866 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ *  Based on meson_uart.c, by AMLOGIC, INC.
+ *
+ * Copyright (C) 2014 Carlo Caione <carlo@caione.org>
+ */
+
+#include <linux/clk.h>
+#include <linux/console.h>
+#include <linux/delay.h>
+#include <linux/init.h>
+#include <linux/io.h>
+#include <linux/iopoll.h>
+#include <linux/module.h>
+#include <linux/kernel.h>
+#include <linux/of.h>
+#include <linux/platform_device.h>
+#include <linux/serial.h>
+#include <linux/serial_core.h>
+#include <linux/tty.h>
+#include <linux/tty_flip.h>
+
+/* Register offsets */
+#define AML_UART_WFIFO			0x00
+#define AML_UART_RFIFO			0x04
+#define AML_UART_CONTROL		0x08
+#define AML_UART_STATUS			0x0c
+#define AML_UART_MISC			0x10
+#define AML_UART_REG5			0x14
+
+/* AML_UART_CONTROL bits */
+#define AML_UART_TX_EN			BIT(12)
+#define AML_UART_RX_EN			BIT(13)
+#define AML_UART_TWO_WIRE_EN		BIT(15)
+#define AML_UART_STOP_BIT_LEN_MASK	(0x03 << 16)
+#define AML_UART_STOP_BIT_1SB		(0x00 << 16)
+#define AML_UART_STOP_BIT_2SB		(0x01 << 16)
+#define AML_UART_PARITY_TYPE		BIT(18)
+#define AML_UART_PARITY_EN		BIT(19)
+#define AML_UART_TX_RST			BIT(22)
+#define AML_UART_RX_RST			BIT(23)
+#define AML_UART_CLEAR_ERR		BIT(24)
+#define AML_UART_RX_INT_EN		BIT(27)
+#define AML_UART_TX_INT_EN		BIT(28)
+#define AML_UART_DATA_LEN_MASK		(0x03 << 20)
+#define AML_UART_DATA_LEN_8BIT		(0x00 << 20)
+#define AML_UART_DATA_LEN_7BIT		(0x01 << 20)
+#define AML_UART_DATA_LEN_6BIT		(0x02 << 20)
+#define AML_UART_DATA_LEN_5BIT		(0x03 << 20)
+
+/* 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_MISC bits */
+#define AML_UART_XMIT_IRQ(c)		(((c) & 0xff) << 8)
+#define AML_UART_RECV_IRQ(c)		((c) & 0xff)
+
+/* AML_UART_REG5 bits */
+#define AML_UART_BAUD_MASK		0x7fffff
+#define AML_UART_BAUD_USE		BIT(23)
+#define AML_UART_BAUD_XTAL		BIT(24)
+#define AML_UART_BAUD_XTAL_DIV2		BIT(27)
+
+#define AML_UART_PORT_NUM		12
+#define AML_UART_PORT_OFFSET		6
+
+#define AML_UART_POLL_USEC		5
+#define AML_UART_TIMEOUT_USEC		10000
+
+static struct uart_driver meson_uart_driver_ttyAML;
+static struct uart_driver meson_uart_driver_ttyS;
+
+static struct uart_port *meson_ports[AML_UART_PORT_NUM];
+
+struct meson_uart_data {
+	struct uart_driver *uart_driver;
+	bool has_xtal_div2;
+};
+
+static void meson_uart_set_mctrl(struct uart_port *port, unsigned int mctrl)
+{
+}
+
+static unsigned int meson_uart_get_mctrl(struct uart_port *port)
+{
+	return TIOCM_CTS;
+}
+
+static unsigned int meson_uart_tx_empty(struct uart_port *port)
+{
+	u32 val;
+
+	val = readl(port->membase + AML_UART_STATUS);
+	val &= (AML_UART_TX_EMPTY | AML_UART_XMIT_BUSY);
+	return (val == AML_UART_TX_EMPTY) ? TIOCSER_TEMT : 0;
+}
+
+static void meson_uart_stop_tx(struct uart_port *port)
+{
+	u32 val;
+
+	val = readl(port->membase + AML_UART_CONTROL);
+	val &= ~AML_UART_TX_INT_EN;
+	writel(val, port->membase + AML_UART_CONTROL);
+}
+
+static void meson_uart_stop_rx(struct uart_port *port)
+{
+	u32 val;
+
+	val = readl(port->membase + AML_UART_CONTROL);
+	val &= ~AML_UART_RX_EN;
+	writel(val, port->membase + AML_UART_CONTROL);
+}
+
+static void meson_uart_shutdown(struct uart_port *port)
+{
+	unsigned long flags;
+	u32 val;
+
+	free_irq(port->irq, port);
+
+	spin_lock_irqsave(&port->lock, flags);
+
+	val = readl(port->membase + AML_UART_CONTROL);
+	val &= ~AML_UART_RX_EN;
+	val &= ~(AML_UART_RX_INT_EN | AML_UART_TX_INT_EN);
+	writel(val, port->membase + AML_UART_CONTROL);
+
+	spin_unlock_irqrestore(&port->lock, flags);
+}
+
+static void meson_uart_start_tx(struct uart_port *port)
+{
+	struct circ_buf *xmit = &port->state->xmit;
+	unsigned int ch;
+	u32 val;
+
+	if (uart_tx_stopped(port)) {
+		meson_uart_stop_tx(port);
+		return;
+	}
+
+	while (!(readl(port->membase + AML_UART_STATUS) & AML_UART_TX_FULL)) {
+		if (port->x_char) {
+			writel(port->x_char, port->membase + AML_UART_WFIFO);
+			port->icount.tx++;
+			port->x_char = 0;
+			continue;
+		}
+
+		if (uart_circ_empty(xmit))
+			break;
+
+		ch = xmit->buf[xmit->tail];
+		writel(ch, port->membase + AML_UART_WFIFO);
+		uart_xmit_advance(port, 1);
+	}
+
+	if (!uart_circ_empty(xmit)) {
+		val = readl(port->membase + AML_UART_CONTROL);
+		val |= AML_UART_TX_INT_EN;
+		writel(val, port->membase + AML_UART_CONTROL);
+	}
+
+	if (uart_circ_chars_pending(xmit) < WAKEUP_CHARS)
+		uart_write_wakeup(port);
+}
+
+static void meson_receive_chars(struct uart_port *port)
+{
+	struct tty_port *tport = &port->state->port;
+	char flag;
+	u32 ostatus, status, ch, mode;
+
+	do {
+		flag = TTY_NORMAL;
+		port->icount.rx++;
+		ostatus = status = readl(port->membase + AML_UART_STATUS);
+
+		if (status & AML_UART_ERR) {
+			if (status & AML_UART_TX_FIFO_WERR)
+				port->icount.overrun++;
+			else if (status & AML_UART_FRAME_ERR)
+				port->icount.frame++;
+			else if (status & AML_UART_PARITY_ERR)
+				port->icount.frame++;
+
+			mode = readl(port->membase + AML_UART_CONTROL);
+			mode |= AML_UART_CLEAR_ERR;
+			writel(mode, port->membase + AML_UART_CONTROL);
+
+			/* It doesn't clear to 0 automatically */
+			mode &= ~AML_UART_CLEAR_ERR;
+			writel(mode, port->membase + AML_UART_CONTROL);
+
+			status &= port->read_status_mask;
+			if (status & AML_UART_FRAME_ERR)
+				flag = TTY_FRAME;
+			else if (status & AML_UART_PARITY_ERR)
+				flag = TTY_PARITY;
+		}
+
+		ch = readl(port->membase + AML_UART_RFIFO);
+		ch &= 0xff;
+
+		if ((ostatus & AML_UART_FRAME_ERR) && (ch == 0)) {
+			port->icount.brk++;
+			flag = TTY_BREAK;
+			if (uart_handle_break(port))
+				continue;
+		}
+
+		if (uart_handle_sysrq_char(port, ch))
+			continue;
+
+		if ((status & port->ignore_status_mask) == 0)
+			tty_insert_flip_char(tport, ch, flag);
+
+		if (status & AML_UART_TX_FIFO_WERR)
+			tty_insert_flip_char(tport, 0, TTY_OVERRUN);
+
+	} while (!(readl(port->membase + AML_UART_STATUS) & AML_UART_RX_EMPTY));
+
+	tty_flip_buffer_push(tport);
+}
+
+static irqreturn_t meson_uart_interrupt(int irq, void *dev_id)
+{
+	struct uart_port *port = (struct uart_port *)dev_id;
+
+	spin_lock(&port->lock);
+
+	if (!(readl(port->membase + AML_UART_STATUS) & AML_UART_RX_EMPTY))
+		meson_receive_chars(port);
+
+	if (!(readl(port->membase + AML_UART_STATUS) & AML_UART_TX_FULL)) {
+		if (readl(port->membase + AML_UART_CONTROL) & AML_UART_TX_INT_EN)
+			meson_uart_start_tx(port);
+	}
+
+	spin_unlock(&port->lock);
+
+	return IRQ_HANDLED;
+}
+
+static const char *meson_uart_type(struct uart_port *port)
+{
+	return (port->type == PORT_MESON) ? "meson_uart" : NULL;
+}
+
+/*
+ * This function is called only from probe() using a temporary io mapping
+ * in order to perform a reset before setting up the device. Since the
+ * temporarily mapped region was successfully requested, there can be no
+ * console on this port at this time. Hence it is not necessary for this
+ * function to acquire the port->lock. (Since there is no console on this
+ * port at this time, the port->lock is not initialized yet.)
+ */
+static void meson_uart_reset(struct uart_port *port)
+{
+	u32 val;
+
+	val = readl(port->membase + AML_UART_CONTROL);
+	val |= (AML_UART_RX_RST | AML_UART_TX_RST | AML_UART_CLEAR_ERR);
+	writel(val, port->membase + AML_UART_CONTROL);
+
+	val &= ~(AML_UART_RX_RST | AML_UART_TX_RST | AML_UART_CLEAR_ERR);
+	writel(val, port->membase + AML_UART_CONTROL);
+}
+
+static int meson_uart_startup(struct uart_port *port)
+{
+	unsigned long flags;
+	u32 val;
+	int ret = 0;
+
+	spin_lock_irqsave(&port->lock, flags);
+
+	val = readl(port->membase + AML_UART_CONTROL);
+	val |= AML_UART_CLEAR_ERR;
+	writel(val, port->membase + AML_UART_CONTROL);
+	val &= ~AML_UART_CLEAR_ERR;
+	writel(val, port->membase + AML_UART_CONTROL);
+
+	val |= (AML_UART_RX_EN | AML_UART_TX_EN);
+	writel(val, port->membase + AML_UART_CONTROL);
+
+	val |= (AML_UART_RX_INT_EN | AML_UART_TX_INT_EN);
+	writel(val, port->membase + AML_UART_CONTROL);
+
+	val = (AML_UART_RECV_IRQ(1) | AML_UART_XMIT_IRQ(port->fifosize / 2));
+	writel(val, port->membase + AML_UART_MISC);
+
+	spin_unlock_irqrestore(&port->lock, flags);
+
+	ret = request_irq(port->irq, meson_uart_interrupt, 0,
+			  port->name, port);
+
+	return ret;
+}
+
+static void meson_uart_change_speed(struct uart_port *port, unsigned long baud)
+{
+	const struct meson_uart_data *private_data = port->private_data;
+	u32 val = 0;
+
+	while (!meson_uart_tx_empty(port))
+		cpu_relax();
+
+	if (port->uartclk == 24000000) {
+		unsigned int xtal_div = 3;
+
+		if (private_data && private_data->has_xtal_div2) {
+			xtal_div = 2;
+			val |= AML_UART_BAUD_XTAL_DIV2;
+		}
+		val |= DIV_ROUND_CLOSEST(port->uartclk / xtal_div, baud) - 1;
+		val |= AML_UART_BAUD_XTAL;
+	} else {
+		val =  DIV_ROUND_CLOSEST(port->uartclk / 4, baud) - 1;
+	}
+	val |= AML_UART_BAUD_USE;
+	writel(val, port->membase + AML_UART_REG5);
+}
+
+static void meson_uart_set_termios(struct uart_port *port,
+				   struct ktermios *termios,
+				   const struct ktermios *old)
+{
+	unsigned int cflags, iflags, baud;
+	unsigned long flags;
+	u32 val;
+
+	spin_lock_irqsave(&port->lock, flags);
+
+	cflags = termios->c_cflag;
+	iflags = termios->c_iflag;
+
+	val = readl(port->membase + AML_UART_CONTROL);
+
+	val &= ~AML_UART_DATA_LEN_MASK;
+	switch (cflags & CSIZE) {
+	case CS8:
+		val |= AML_UART_DATA_LEN_8BIT;
+		break;
+	case CS7:
+		val |= AML_UART_DATA_LEN_7BIT;
+		break;
+	case CS6:
+		val |= AML_UART_DATA_LEN_6BIT;
+		break;
+	case CS5:
+		val |= AML_UART_DATA_LEN_5BIT;
+		break;
+	}
+
+	if (cflags & PARENB)
+		val |= AML_UART_PARITY_EN;
+	else
+		val &= ~AML_UART_PARITY_EN;
+
+	if (cflags & PARODD)
+		val |= AML_UART_PARITY_TYPE;
+	else
+		val &= ~AML_UART_PARITY_TYPE;
+
+	val &= ~AML_UART_STOP_BIT_LEN_MASK;
+	if (cflags & CSTOPB)
+		val |= AML_UART_STOP_BIT_2SB;
+	else
+		val |= AML_UART_STOP_BIT_1SB;
+
+	if (cflags & CRTSCTS) {
+		if (port->flags & UPF_HARD_FLOW)
+			val &= ~AML_UART_TWO_WIRE_EN;
+		else
+			termios->c_cflag &= ~CRTSCTS;
+	} else {
+		val |= AML_UART_TWO_WIRE_EN;
+	}
+
+	writel(val, port->membase + AML_UART_CONTROL);
+
+	baud = uart_get_baud_rate(port, termios, old, 50, 4000000);
+	meson_uart_change_speed(port, baud);
+
+	port->read_status_mask = AML_UART_TX_FIFO_WERR;
+	if (iflags & INPCK)
+		port->read_status_mask |= AML_UART_PARITY_ERR |
+					  AML_UART_FRAME_ERR;
+
+	port->ignore_status_mask = 0;
+	if (iflags & IGNPAR)
+		port->ignore_status_mask |= AML_UART_PARITY_ERR |
+					    AML_UART_FRAME_ERR;
+
+	uart_update_timeout(port, termios->c_cflag, baud);
+	spin_unlock_irqrestore(&port->lock, flags);
+}
+
+static int meson_uart_verify_port(struct uart_port *port,
+				  struct serial_struct *ser)
+{
+	int ret = 0;
+
+	if (port->type != PORT_MESON)
+		ret = -EINVAL;
+	if (port->irq != ser->irq)
+		ret = -EINVAL;
+	if (ser->baud_base < 9600)
+		ret = -EINVAL;
+	return ret;
+}
+
+static void meson_uart_release_port(struct uart_port *port)
+{
+	devm_iounmap(port->dev, port->membase);
+	port->membase = NULL;
+	devm_release_mem_region(port->dev, port->mapbase, port->mapsize);
+}
+
+static int meson_uart_request_port(struct uart_port *port)
+{
+	if (!devm_request_mem_region(port->dev, port->mapbase, port->mapsize,
+				     dev_name(port->dev))) {
+		dev_err(port->dev, "Memory region busy\n");
+		return -EBUSY;
+	}
+
+	port->membase = devm_ioremap(port->dev, port->mapbase,
+					     port->mapsize);
+	if (!port->membase)
+		return -ENOMEM;
+
+	return 0;
+}
+
+static void meson_uart_config_port(struct uart_port *port, int flags)
+{
+	if (flags & UART_CONFIG_TYPE) {
+		port->type = PORT_MESON;
+		meson_uart_request_port(port);
+	}
+}
+
+#ifdef CONFIG_CONSOLE_POLL
+/*
+ * Console polling routines for writing and reading from the uart while
+ * in an interrupt or debug context (i.e. kgdb).
+ */
+
+static int meson_uart_poll_get_char(struct uart_port *port)
+{
+	u32 c;
+	unsigned long flags;
+
+	spin_lock_irqsave(&port->lock, flags);
+
+	if (readl(port->membase + AML_UART_STATUS) & AML_UART_RX_EMPTY)
+		c = NO_POLL_CHAR;
+	else
+		c = readl(port->membase + AML_UART_RFIFO);
+
+	spin_unlock_irqrestore(&port->lock, flags);
+
+	return c;
+}
+
+static void meson_uart_poll_put_char(struct uart_port *port, unsigned char c)
+{
+	unsigned long flags;
+	u32 reg;
+	int ret;
+
+	spin_lock_irqsave(&port->lock, flags);
+
+	/* Wait until FIFO is empty or timeout */
+	ret = readl_poll_timeout_atomic(port->membase + AML_UART_STATUS, reg,
+					reg & AML_UART_TX_EMPTY,
+					AML_UART_POLL_USEC,
+					AML_UART_TIMEOUT_USEC);
+	if (ret == -ETIMEDOUT) {
+		dev_err(port->dev, "Timeout waiting for UART TX EMPTY\n");
+		goto out;
+	}
+
+	/* Write the character */
+	writel(c, port->membase + AML_UART_WFIFO);
+
+	/* Wait until FIFO is empty or timeout */
+	ret = readl_poll_timeout_atomic(port->membase + AML_UART_STATUS, reg,
+					reg & AML_UART_TX_EMPTY,
+					AML_UART_POLL_USEC,
+					AML_UART_TIMEOUT_USEC);
+	if (ret == -ETIMEDOUT)
+		dev_err(port->dev, "Timeout waiting for UART TX EMPTY\n");
+
+out:
+	spin_unlock_irqrestore(&port->lock, flags);
+}
+
+#endif /* CONFIG_CONSOLE_POLL */
+
+static const struct uart_ops meson_uart_ops = {
+	.set_mctrl      = meson_uart_set_mctrl,
+	.get_mctrl      = meson_uart_get_mctrl,
+	.tx_empty	= meson_uart_tx_empty,
+	.start_tx	= meson_uart_start_tx,
+	.stop_tx	= meson_uart_stop_tx,
+	.stop_rx	= meson_uart_stop_rx,
+	.startup	= meson_uart_startup,
+	.shutdown	= meson_uart_shutdown,
+	.set_termios	= meson_uart_set_termios,
+	.type		= meson_uart_type,
+	.config_port	= meson_uart_config_port,
+	.request_port	= meson_uart_request_port,
+	.release_port	= meson_uart_release_port,
+	.verify_port	= meson_uart_verify_port,
+#ifdef CONFIG_CONSOLE_POLL
+	.poll_get_char	= meson_uart_poll_get_char,
+	.poll_put_char	= meson_uart_poll_put_char,
+#endif
+};
+
+#ifdef CONFIG_SERIAL_MESON_CONSOLE
+static void meson_uart_enable_tx_engine(struct uart_port *port)
+{
+	u32 val;
+
+	val = readl(port->membase + AML_UART_CONTROL);
+	val |= AML_UART_TX_EN;
+	writel(val, port->membase + AML_UART_CONTROL);
+}
+
+static void meson_console_putchar(struct uart_port *port, unsigned char ch)
+{
+	if (!port->membase)
+		return;
+
+	while (readl(port->membase + AML_UART_STATUS) & AML_UART_TX_FULL)
+		cpu_relax();
+	writel(ch, port->membase + AML_UART_WFIFO);
+}
+
+static void meson_serial_port_write(struct uart_port *port, const char *s,
+				    u_int count)
+{
+	unsigned long flags;
+	int locked;
+	u32 val, tmp;
+
+	local_irq_save(flags);
+	if (port->sysrq) {
+		locked = 0;
+	} else if (oops_in_progress) {
+		locked = spin_trylock(&port->lock);
+	} else {
+		spin_lock(&port->lock);
+		locked = 1;
+	}
+
+	val = readl(port->membase + AML_UART_CONTROL);
+	tmp = val & ~(AML_UART_TX_INT_EN | AML_UART_RX_INT_EN);
+	writel(tmp, port->membase + AML_UART_CONTROL);
+
+	uart_console_write(port, s, count, meson_console_putchar);
+	writel(val, port->membase + AML_UART_CONTROL);
+
+	if (locked)
+		spin_unlock(&port->lock);
+	local_irq_restore(flags);
+}
+
+static void meson_serial_console_write(struct console *co, const char *s,
+				       u_int count)
+{
+	struct uart_port *port;
+
+	port = meson_ports[co->index];
+	if (!port)
+		return;
+
+	meson_serial_port_write(port, s, count);
+}
+
+static int meson_serial_console_setup(struct console *co, char *options)
+{
+	struct uart_port *port;
+	int baud = 115200;
+	int bits = 8;
+	int parity = 'n';
+	int flow = 'n';
+
+	if (co->index < 0 || co->index >= AML_UART_PORT_NUM)
+		return -EINVAL;
+
+	port = meson_ports[co->index];
+	if (!port || !port->membase)
+		return -ENODEV;
+
+	meson_uart_enable_tx_engine(port);
+
+	if (options)
+		uart_parse_options(options, &baud, &parity, &bits, &flow);
+
+	return uart_set_options(port, co, baud, parity, bits, flow);
+}
+
+#define MESON_SERIAL_CONSOLE(_devname)					\
+	static struct console meson_serial_console_##_devname = {	\
+		.name		= __stringify(_devname),		\
+		.write		= meson_serial_console_write,		\
+		.device		= uart_console_device,			\
+		.setup		= meson_serial_console_setup,		\
+		.flags		= CON_PRINTBUFFER,			\
+		.index		= -1,					\
+		.data		= &meson_uart_driver_##_devname,	\
+	}
+
+MESON_SERIAL_CONSOLE(ttyAML);
+MESON_SERIAL_CONSOLE(ttyS);
+
+static void meson_serial_early_console_write(struct console *co,
+					     const char *s,
+					     u_int count)
+{
+	struct earlycon_device *dev = co->data;
+
+	meson_serial_port_write(&dev->port, s, count);
+}
+
+static int __init
+meson_serial_early_console_setup(struct earlycon_device *device, const char *opt)
+{
+	if (!device->port.membase)
+		return -ENODEV;
+
+	meson_uart_enable_tx_engine(&device->port);
+	device->con->write = meson_serial_early_console_write;
+	return 0;
+}
+
+OF_EARLYCON_DECLARE(meson, "amlogic,meson-ao-uart",
+		    meson_serial_early_console_setup);
+
+#define MESON_SERIAL_CONSOLE_PTR(_devname) (&meson_serial_console_##_devname)
+#else
+#define MESON_SERIAL_CONSOLE_PTR(_devname) (NULL)
+#endif
+
+#define MESON_UART_DRIVER(_devname)					\
+	static struct uart_driver meson_uart_driver_##_devname = {	\
+		.owner		= THIS_MODULE,				\
+		.driver_name	= "meson_uart",				\
+		.dev_name	= __stringify(_devname),		\
+		.nr		= AML_UART_PORT_NUM,			\
+		.cons		= MESON_SERIAL_CONSOLE_PTR(_devname),	\
+	}
+
+MESON_UART_DRIVER(ttyAML);
+MESON_UART_DRIVER(ttyS);
+
+static int meson_uart_probe_clocks(struct platform_device *pdev,
+				   struct uart_port *port)
+{
+	struct clk *clk_xtal = NULL;
+	struct clk *clk_pclk = NULL;
+	struct clk *clk_baud = NULL;
+
+	clk_pclk = devm_clk_get_enabled(&pdev->dev, "pclk");
+	if (IS_ERR(clk_pclk))
+		return PTR_ERR(clk_pclk);
+
+	clk_xtal = devm_clk_get_enabled(&pdev->dev, "xtal");
+	if (IS_ERR(clk_xtal))
+		return PTR_ERR(clk_xtal);
+
+	clk_baud = devm_clk_get_enabled(&pdev->dev, "baud");
+	if (IS_ERR(clk_baud))
+		return PTR_ERR(clk_baud);
+
+	port->uartclk = clk_get_rate(clk_baud);
+
+	return 0;
+}
+
+static struct uart_driver *meson_uart_current(const struct meson_uart_data *pd)
+{
+	return (pd && pd->uart_driver) ?
+		pd->uart_driver : &meson_uart_driver_ttyAML;
+}
+
+static int meson_uart_probe(struct platform_device *pdev)
+{
+	const struct meson_uart_data *priv_data;
+	struct uart_driver *uart_driver;
+	struct resource *res_mem;
+	struct uart_port *port;
+	u32 fifosize = 64; /* Default is 64, 128 for EE UART_0 */
+	int ret = 0;
+	int irq;
+	bool has_rtscts;
+
+	if (pdev->dev.of_node)
+		pdev->id = of_alias_get_id(pdev->dev.of_node, "serial");
+
+	if (pdev->id < 0) {
+		int id;
+
+		for (id = AML_UART_PORT_OFFSET; id < AML_UART_PORT_NUM; id++) {
+			if (!meson_ports[id]) {
+				pdev->id = id;
+				break;
+			}
+		}
+	}
+
+	if (pdev->id < 0 || pdev->id >= AML_UART_PORT_NUM)
+		return -EINVAL;
+
+	res_mem = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+	if (!res_mem)
+		return -ENODEV;
+
+	irq = platform_get_irq(pdev, 0);
+	if (irq < 0)
+		return irq;
+
+	of_property_read_u32(pdev->dev.of_node, "fifo-size", &fifosize);
+	has_rtscts = of_property_read_bool(pdev->dev.of_node, "uart-has-rtscts");
+
+	if (meson_ports[pdev->id]) {
+		return dev_err_probe(&pdev->dev, -EBUSY,
+				     "port %d already allocated\n", pdev->id);
+	}
+
+	port = devm_kzalloc(&pdev->dev, sizeof(struct uart_port), GFP_KERNEL);
+	if (!port)
+		return -ENOMEM;
+
+	ret = meson_uart_probe_clocks(pdev, port);
+	if (ret)
+		return ret;
+
+	priv_data = device_get_match_data(&pdev->dev);
+
+	uart_driver = meson_uart_current(priv_data);
+
+	if (!uart_driver->state) {
+		ret = uart_register_driver(uart_driver);
+		if (ret)
+			return dev_err_probe(&pdev->dev, ret,
+					     "can't register uart driver\n");
+	}
+
+	port->iotype = UPIO_MEM;
+	port->mapbase = res_mem->start;
+	port->mapsize = resource_size(res_mem);
+	port->irq = irq;
+	port->flags = UPF_BOOT_AUTOCONF | UPF_LOW_LATENCY;
+	if (has_rtscts)
+		port->flags |= UPF_HARD_FLOW;
+	port->has_sysrq = IS_ENABLED(CONFIG_SERIAL_MESON_CONSOLE);
+	port->dev = &pdev->dev;
+	port->line = pdev->id;
+	port->type = PORT_MESON;
+	port->x_char = 0;
+	port->ops = &meson_uart_ops;
+	port->fifosize = fifosize;
+	port->private_data = (void *)priv_data;
+
+	meson_ports[pdev->id] = port;
+	platform_set_drvdata(pdev, port);
+
+	/* reset port before registering (and possibly registering console) */
+	if (meson_uart_request_port(port) >= 0) {
+		meson_uart_reset(port);
+		meson_uart_release_port(port);
+	}
+
+	ret = uart_add_one_port(uart_driver, port);
+	if (ret)
+		meson_ports[pdev->id] = NULL;
+
+	return ret;
+}
+
+static int meson_uart_remove(struct platform_device *pdev)
+{
+	struct uart_driver *uart_driver;
+	struct uart_port *port;
+
+	port = platform_get_drvdata(pdev);
+	uart_driver = meson_uart_current(port->private_data);
+	uart_remove_one_port(uart_driver, port);
+	meson_ports[pdev->id] = NULL;
+
+	for (int id = 0; id < AML_UART_PORT_NUM; id++)
+		if (meson_ports[id])
+			return 0;
+
+	/* No more available uart ports, unregister uart driver */
+	uart_unregister_driver(uart_driver);
+
+	return 0;
+}
+
+static struct meson_uart_data meson_g12a_uart_data = {
+	.has_xtal_div2 = true,
+};
+
+static struct meson_uart_data meson_a1_uart_data = {
+	.uart_driver = &meson_uart_driver_ttyS,
+	.has_xtal_div2 = false,
+};
+
+static struct meson_uart_data meson_s4_uart_data = {
+	.uart_driver = &meson_uart_driver_ttyS,
+	.has_xtal_div2 = true,
+};
+
+static const struct of_device_id meson_uart_dt_match[] = {
+	{ .compatible = "amlogic,meson6-uart" },
+	{ .compatible = "amlogic,meson8-uart" },
+	{ .compatible = "amlogic,meson8b-uart" },
+	{ .compatible = "amlogic,meson-gx-uart" },
+	{
+		.compatible = "amlogic,meson-g12a-uart",
+		.data = (void *)&meson_g12a_uart_data,
+	},
+	{
+		.compatible = "amlogic,meson-s4-uart",
+		.data = (void *)&meson_s4_uart_data,
+	},
+	{
+		.compatible = "amlogic,meson-a1-uart",
+		.data = (void *)&meson_a1_uart_data,
+	},
+	{ /* sentinel */ },
+};
+MODULE_DEVICE_TABLE(of, meson_uart_dt_match);
+
+static  struct platform_driver meson_uart_platform_driver = {
+	.probe		= meson_uart_probe,
+	.remove		= meson_uart_remove,
+	.driver		= {
+		.name		= "meson_uart",
+		.of_match_table	= meson_uart_dt_match,
+	},
+};
+
+module_platform_driver(meson_uart_platform_driver);
+
+MODULE_AUTHOR("Carlo Caione <carlo@caione.org>");
+MODULE_DESCRIPTION("Amlogic Meson serial port driver");
+MODULE_LICENSE("GPL v2");