drivers/amlogic/uart/meson_uart.c

/*
 * drivers/amlogic/uart/meson_uart.c
 *
 * Copyright (C) 2017 Amlogic, Inc. All rights reserved.
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
 * more details.
 *
 */

#include <linux/clk.h>
#include <linux/console.h>
#include <linux/delay.h>
#include <linux/init.h>
#include <linux/io.h>
#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/of.h>
#include <linux/platform_device.h>
#include <linux/serial.h>
#include <linux/tty.h>
#include <linux/tty_flip.h>
#include <linux/pinctrl/consumer.h>
#include <linux/clk-provider.h>
#include <linux/amlogic/iomap.h>

#if defined(CONFIG_AMLOGIC_SERIAL_MESON_CONSOLE) && defined(CONFIG_MAGIC_SYSRQ)
#define SUPPORT_SYSRQ
#endif
#include <linux/serial_core.h>

#include <linux/vmalloc.h>
#include "meson_uart.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_TX_RST			BIT(22)
#define AML_UART_RX_RST			BIT(23)
#define AML_UART_CLR_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_RX_FIFO_OVERFLOW	BIT(24)
#define AML_UART_ERR			(AML_UART_PARITY_ERR | \
					 AML_UART_FRAME_ERR  | \
					 AML_UART_RX_FIFO_OVERFLOW)

/* AML_UART_CONTROL bits */
#define AML_UART_TWO_WIRE_EN		BIT(15)
#define AML_UART_PARITY_TYPE		BIT(18)
#define AML_UART_PARITY_EN		BIT(19)
#define AML_UART_CLEAR_ERR		BIT(24)
#define AML_UART_STOP_BIN_LEN_MASK	(0x03 << 16)
#define AML_UART_STOP_BIN_1SB		(0x00 << 16)
#define AML_UART_STOP_BIN_2SB		(0x01 << 16)

/* 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_TICK	BIT(26)
#define AML_UART_BAUD_XTAL_DIV2	BIT(27)


#define AML_UART_PORT_MAX		16
#define AML_UART_DEV_NAME		"ttyS"

/*#define UART_TEST_DEBUG*/
static struct uart_driver meson_uart_driver;
unsigned int xtal_tick_en;
struct meson_uart_port {
	struct uart_port	port;
	spinlock_t wr_lock;
	unsigned long baud;
	struct pinctrl *p;
};

#define to_meson_port(uport)  container_of(uport, struct meson_uart_port, port)
static struct meson_uart_port *meson_ports[AML_UART_PORT_MAX];

struct uart_port *get_uart_port(int id)
{
	struct uart_port *port;

	port = &meson_ports[id]->port;
	return port;
}
EXPORT_SYMBOL(get_uart_port);
static int meson_serial_console_setup(struct console *co, char *options);


/*************** printk noblock *****************/

#define MESON_SERIAL_BUFFER_SIZE (1024 * 128)
#define DEFAULT_STR_LEN	4
#define DEFAULT_STR   "..."

/*0: disable   1: enable*/
static bool new_printk_enabled;

struct meson_uart_struct {
	struct console *co;
	const char *s;
	unsigned long offset;
	long count;
	struct list_head list;
};
struct meson_uart_management {
	int user_count;
	struct list_head list_head;
	spinlock_t lock;
};
struct meson_uart_list {
	int user_count;
	struct meson_uart_struct *co_head;
	struct meson_uart_struct *co_tail;
};

static struct meson_uart_management cur_col_management;
static struct meson_uart_list cur_col_list[AML_UART_PORT_MAX];
static char *data_cache;
static int meson_uart_console_index =  -1;

static int __init new_printk_enable(char *str)
{
	new_printk_enabled = 1;
	return 1;
}
__setup("printk_no_block", new_printk_enable);


module_param_named(new_printk, new_printk_enabled,
		bool, 0644);

MODULE_PARM_DESC(new_printk, "printk use no block mode");

static ssize_t printk_mode_show(struct device_driver *drv, char *buf)
{
	return sprintf(buf, "0x%0x\n",  new_printk_enabled);
}

static ssize_t printk_mode_store(struct device_driver *drv, const char *buf,
			       size_t count)
{
	unsigned long long res = 0;

	if (!kstrtoull(buf, 16, &res))
		new_printk_enabled = res;
	return count;
}

static DRIVER_ATTR(printkmode, 0644, printk_mode_show,
		   printk_mode_store);


/***********  SYSRQ  **************/
static int support_sysrq;

static ssize_t support_sysrq_show(struct device_driver *drv, char *buf)
{
	return sprintf(buf, "0x%0x\n",  support_sysrq);
}

static ssize_t support_sysrq_store(struct device_driver *drv, const char *buf,
			       size_t count)
{
	unsigned long long res = 0;

	if (!kstrtoull(buf, 16, &res))
		support_sysrq = res;
	return count;
}

static DRIVER_ATTR(sysrqsupport, 0644, support_sysrq_show,
		   support_sysrq_store);


static void get_next_node(struct meson_uart_list *cur_col,
				struct meson_uart_struct *co_struct, int index)
{
	struct list_head *entry;
	struct console *co = NULL;
	struct list_head *list_head = NULL;

	cur_col->user_count--;

	list_del(&co_struct->list);

	co_struct = NULL;
	list_head = &cur_col_management.list_head;
	if (!list_empty(list_head)) {
		cur_col_management.user_count--;
		list_for_each_prev(entry, list_head) {
			co_struct = list_entry(entry,
				struct meson_uart_struct, list);
			co = co_struct->co;
			if (co->index == index)
				break;
		}
	}
	if (co_struct && (co->index == index)) {
		cur_col->co_head = co_struct;
	} else {
		cur_col->co_head = NULL;
		cur_col->co_tail = NULL;
		cur_col->user_count = 0;
	}
}
static int print_more(struct meson_uart_port *mup)
{
	int index = 0;
	struct meson_uart_struct *co_struct = NULL;
	struct meson_uart_port *mup_tmp = NULL;
	struct meson_uart_list *cur_col = NULL;
	struct console *co = NULL;
	const char *s = NULL;
	unsigned long flags = 0;

	spin_lock_irqsave(&cur_col_management.lock, flags);
	if (!data_cache || list_empty(&cur_col_management.list_head))
		goto no_data_print;

	for (index = 0; index < AML_UART_PORT_MAX; index++) {
		mup_tmp = meson_ports[index];
		if (mup == mup_tmp)
			break;
	}
	if (index >= AML_UART_PORT_MAX)
		goto no_data_print;

	cur_col = &cur_col_list[index];
	if ((cur_col->user_count == 0) || !cur_col->co_head)
		goto no_data_print;

	co_struct = cur_col->co_head;
	co = co_struct->co;
	index = co->index;
	if (index < 0)
		goto no_data_print;

	spin_lock(&mup->wr_lock);
	if (index != meson_uart_console_index)
		meson_serial_console_setup(co, NULL);

	while ((readl(mup->port.membase + AML_UART_CONTROL) & AML_UART_TX_EN)
		&& (!(readl(mup->port.membase + AML_UART_STATUS)
		& AML_UART_TX_FULL))) {
		if (co_struct->count <= 0) {
			get_next_node(cur_col, co_struct, index);
			if (!cur_col->co_head)
				break;
			co_struct = cur_col->co_head;
		}
		s = co_struct->s + co_struct->offset;
		if (*s == '\n')
			writel('\r', mup->port.membase + AML_UART_WFIFO);
		writel(*s++, mup->port.membase + AML_UART_WFIFO);
		co_struct->count--;
		co_struct->offset++;
	}

	spin_unlock(&mup->wr_lock);

no_data_print:
	spin_unlock_irqrestore(&cur_col_management.lock, flags);
	return 0;
}

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);
	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_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;

	if (port->line == 0)
		return;

	spin_lock_irqsave(&port->lock, flags);

	val = readl(port->membase + AML_UART_CONTROL);
	val &= ~(AML_UART_RX_EN | AML_UART_TX_EN);
	val &= ~(AML_UART_RX_INT_EN | AML_UART_TX_INT_EN);
	val |= UART_CTS_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;
	struct meson_uart_port *mup = to_meson_port(port);
	unsigned long flags;

	spin_lock_irqsave(&mup->wr_lock, flags);
	while (!uart_circ_empty(xmit)) {
		if (!(readl(port->membase + AML_UART_STATUS) &
			AML_UART_TX_FULL)) {
			ch = xmit->buf[xmit->tail];
			writel(ch, port->membase + AML_UART_WFIFO);
			xmit->tail = (xmit->tail + 1) & (SERIAL_XMIT_SIZE - 1);
			port->icount.tx++;
		} else
			break;
	}
	spin_unlock_irqrestore(&mup->wr_lock, flags);
}

static void meson_transmit_chars(struct uart_port *port)
{
	struct circ_buf *xmit = &port->state->xmit;
	struct meson_uart_port *mup = to_meson_port(port);
	unsigned int ch;
	int count = 256;

	spin_lock(&port->lock);
	if (port->x_char) {
		writel(port->x_char, port->membase + AML_UART_WFIFO);
		port->icount.tx++;
		port->x_char = 0;
		goto clear_and_return;
	}

	if (uart_circ_empty(xmit) || uart_tx_stopped(port))
		goto clear_and_return;

	spin_lock(&mup->wr_lock);
	while (!uart_circ_empty(xmit) && count-- > 0) {
		if (!(readl(port->membase + AML_UART_STATUS) &
			AML_UART_TX_FULL)) {
			ch = xmit->buf[xmit->tail];
			writel(ch, port->membase + AML_UART_WFIFO);
			xmit->tail = (xmit->tail + 1) & (SERIAL_XMIT_SIZE - 1);
			port->icount.tx++;
		} else
			break;
	}
	spin_unlock(&mup->wr_lock);

	if (uart_circ_chars_pending(xmit) < WAKEUP_CHARS)
		uart_write_wakeup(port);

 clear_and_return:
	spin_unlock(&port->lock);
	return;

}

static void meson_receive_chars(struct uart_port *port)
{
	struct tty_port *tport = &port->state->port;
	char flag;
	u32 status, ch, mode;

	spin_lock(&port->lock);
	do {
		flag = TTY_NORMAL;
		port->icount.rx++;
		status = readl(port->membase + AML_UART_STATUS);

		if (status & AML_UART_ERR) {
			if (status & AML_UART_RX_FIFO_OVERFLOW)
				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 |
				AML_UART_RX_FIFO_OVERFLOW))
				flag = TTY_FRAME;
			else if (status & AML_UART_PARITY_ERR)
				flag = TTY_PARITY;
		}

		ch = readl(port->membase + AML_UART_RFIFO);
		ch &= 0xff;

#ifdef SUPPORT_SYSRQ
		if (support_sysrq == 1) {
			if ((status == 0) && (ch == 0)) {
				port->icount.brk++;
				if (uart_handle_break(port))
					continue;
			}

			if (port->sysrq)
				flag = TTY_BREAK;

			if (uart_handle_sysrq_char(port, ch))
				continue;
		}
#endif

		uart_insert_char(port, status, AML_UART_RX_FIFO_OVERFLOW,
				 ch, flag);
		/*
		 * 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));
	spin_unlock(&port->lock);

	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;
	u32 val;
	struct meson_uart_port *mup = to_meson_port(port);

	spin_lock(&port->lock);
	val = readl(port->membase + AML_UART_CONTROL);
	spin_unlock(&port->lock);
	if (!(readl(port->membase + AML_UART_STATUS) & AML_UART_RX_EMPTY))
		meson_receive_chars(port);

	if ((val & AML_UART_TX_EN)
	    && (!(readl(port->membase + AML_UART_STATUS) & AML_UART_TX_FULL)))
		meson_transmit_chars(port);

	if (!list_empty(&cur_col_management.list_head))
		print_more(mup);

	return IRQ_HANDLED;
}

static const char *meson_uart_type(struct uart_port *port)
{
	return (port->type == PORT_MESON) ? "meson_uart" : NULL;
}

static int meson_uart_startup(struct uart_port *port)
{
	u32 val;
	int ret = 0;

	val = readl(port->membase + AML_UART_CONTROL);
	val |= (AML_UART_RX_RST | AML_UART_TX_RST | AML_UART_CLR_ERR);
	writel(val, port->membase + AML_UART_CONTROL);

	val &= ~(AML_UART_RX_RST | AML_UART_TX_RST | AML_UART_CLR_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);
	val &= ~UART_CTS_EN;
	writel(val, port->membase + AML_UART_CONTROL);

	return ret;
}

static void meson_uart_change_speed(struct uart_port *port, unsigned long baud)
{
	u32 val;
	struct meson_uart_port *mup = to_meson_port(port);
	struct platform_device *pdev = to_platform_device(port->dev);

	while (!(readl(port->membase + AML_UART_STATUS) & AML_UART_TX_EMPTY))
		cpu_relax();

#ifdef UART_TEST_DEBUG
	if (port->line != 0)
		baud = 115200;
#endif
	val = readl(port->membase + AML_UART_REG5);
	val &= ~AML_UART_BAUD_MASK;
	if (port->uartclk == 24000000) {
		if (xtal_tick_en) {
			/*xtal_tick_en first*/
			aml_aobus_update_bits((0x19<<2), (1<<18), (1<<18));
			dev_info(&pdev->dev, "ttyS%d use xtal(24M) %d change %ld to %ld\n",
				port->line, port->uartclk,
				mup->baud, baud);
			if (xtal_tick_en == 1) {
				val = (port->uartclk + baud / 2) / baud  - 1;
				val |= (AML_UART_BAUD_USE|AML_UART_BAUD_XTAL
					|AML_UART_BAUD_XTAL_TICK);
			} else if (xtal_tick_en == 2) {
				val = (port->uartclk/2 + baud / 2) / baud  - 1;
				val |= (AML_UART_BAUD_USE|AML_UART_BAUD_XTAL
					|AML_UART_BAUD_XTAL_DIV2);
			}
		} else {
			dev_info(&pdev->dev, "ttyS%d use xtal(8M) %d change %ld to %ld\n",
				port->line, port->uartclk,
				mup->baud, baud);
			val = ((port->uartclk / 3) + baud / 2) / baud  - 1;
			val &= (~AML_UART_BAUD_XTAL_TICK);
			val |= (AML_UART_BAUD_USE|AML_UART_BAUD_XTAL);
		}
	} else {
		dev_info(&pdev->dev, "ttyS%d use clk81 %d change %ld to %ld\n",
			port->line, port->uartclk,
			mup->baud, baud);
		val = ((port->uartclk * 10 / (baud * 4) + 5) / 10) - 1;
		val &= (~(AML_UART_BAUD_XTAL|AML_UART_BAUD_XTAL_TICK));
		val |= AML_UART_BAUD_USE;
	}
	writel(val, port->membase + AML_UART_REG5);

	mup->baud = baud;
}

static void meson_uart_set_termios(struct uart_port *port,
				   struct ktermios *termios,
				   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_BIN_LEN_MASK;
	if (cflags & CSTOPB)
		val |= AML_UART_STOP_BIN_2SB;
	else
		val &= ~AML_UART_STOP_BIN_1SB;

	if (cflags & CRTSCTS)
		val &= ~AML_UART_TWO_WIRE_EN;
	else
		val |= AML_UART_TWO_WIRE_EN;

	writel(val, port->membase + AML_UART_CONTROL);
	spin_unlock_irqrestore(&port->lock, flags);

	baud = uart_get_baud_rate(port, termios, old, 2400, 4000000);
	meson_uart_change_speed(port, baud);

	port->read_status_mask = AML_UART_RX_FIFO_OVERFLOW;
	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);
}

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)
{
	if (port->flags & UPF_IOREMAP) {
		iounmap(port->membase);
		port->membase = NULL;
	}
}

static int meson_uart_request_port(struct uart_port *port)
{
	struct platform_device *pdev = to_platform_device(port->dev);
	struct resource *res;
	int size, ret;
	u32 val;

	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
	if (!res) {
		dev_err(&pdev->dev, "cannot obtain I/O memory region");
		return -ENODEV;
	}
	size = resource_size(res);

	if (!devm_request_mem_region(port->dev, port->mapbase, size,
				     dev_name(port->dev))) {
		dev_err(port->dev, "Memory region busy\n");
		return -EBUSY;
	}

	if (port->flags & UPF_IOREMAP) {
		port->membase = devm_ioremap_nocache(port->dev,
						     port->mapbase, size);
		if (port->membase == NULL)
			return -ENOMEM;
	}

	dev_info(&pdev->dev, "==uart%d reg addr = %p\n",
						port->line, port->membase);
	val = (AML_UART_RECV_IRQ(1) | AML_UART_XMIT_IRQ(port->fifosize / 2));
	writel(val, port->membase + AML_UART_MISC);

	writel(readl(port->membase + AML_UART_CONTROL) | UART_CTS_EN,
			port->membase + AML_UART_CONTROL);

	ret = request_irq(port->irq, meson_uart_interrupt, 0,
			  meson_uart_type(port), port);
	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);
	}
}

static struct uart_ops const 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_AMLOGIC_SERIAL_MESON_CONSOLE

static void meson_console_putchar(struct uart_port *port, int 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_console_write(struct console *co, const char *s,
				       u_int count)
{
	struct uart_port *port;

	const char *cur_s = NULL;
	struct meson_uart_struct *head_s = NULL;
	struct meson_uart_struct *tail_s = NULL;
	struct list_head *list_head = NULL;
	struct meson_uart_struct *co_struct = NULL;
	struct meson_uart_list *cur_col = NULL;
	long tmp_count = 0;
	long tmp_count_1 = 0;
	long struct_size = sizeof(struct meson_uart_struct);
	int need_default = 0;
	static int last_msg_full;
	unsigned long flags = 0;
	int index = co->index;

	port = &meson_ports[co->index]->port;
	if (!port)
		return;
	if (!new_printk_enabled || !data_cache) {
		uart_console_write(port, s, count, meson_console_putchar);
		return;
	}

	spin_lock_irqsave(&cur_col_management.lock, flags);

	if (count > 0 && count < MESON_SERIAL_BUFFER_SIZE) {
		list_head = &cur_col_management.list_head;
		cur_s = NULL;
		if (list_empty(list_head)) {
			cur_s = data_cache;
		} else {
			head_s = list_entry(list_head->prev,
				struct meson_uart_struct, list);
			tail_s = list_entry(list_head->next,
				struct meson_uart_struct, list);
			tmp_count_1 = (struct_size << 1)
				+ (unsigned long)tail_s->s + tail_s->offset
				+ tail_s->count;
			if (head_s->s <= tail_s->s) {
				tmp_count = data_cache
					+ MESON_SERIAL_BUFFER_SIZE
					- tail_s->s - tail_s->offset
					- tail_s->count;
				if (tmp_count < (long long)count + struct_size
					+ (struct_size+DEFAULT_STR_LEN)) {
					if ((head_s->s > (data_cache
						+ (struct_size << 1)))
						&& ((head_s->s -
						(data_cache
						+ (struct_size << 1)))
						> count
						+(struct_size
						+DEFAULT_STR_LEN))) {
						cur_s = data_cache;
					} else if (tmp_count > (struct_size +
						DEFAULT_STR_LEN)) {
						cur_s = tail_s->s +
						tail_s->offset + tail_s->count;
						need_default = 1;
					} else {
						cur_s = data_cache;
						need_default = 1;
					}
				} else {
					cur_s = tail_s->s + tail_s->offset
						+ tail_s->count;
				}
			} else if (((long)head_s->s > tmp_count_1)
			&& ((long)head_s->s - tmp_count_1
			> count + (struct_size+DEFAULT_STR_LEN))) {
				cur_s = tail_s->s + tail_s->offset
						+ tail_s->count;
			} else {
				cur_s = tail_s->s + tail_s->offset
						+ tail_s->count;
				need_default = 1;
			}
		}

		if (need_default == 0) {
			co_struct = (struct meson_uart_struct *)cur_s;
			co_struct->s = cur_s + struct_size;
			co_struct->count = count;
			co_struct->co = co;
			co_struct->offset = 0;
			cur_col = &cur_col_list[index];
			cur_col->co_tail = co_struct;
			if (!cur_col->co_head)
				cur_col->co_head = co_struct;

			cur_col->user_count++;
			cur_col_management.user_count++;
			memcpy((char *)(co_struct->s), (char *)s, count);
			list_add(&co_struct->list,
					&cur_col_management.list_head);
			last_msg_full = 0;
		} else {
			if (last_msg_full == 0) {
				co_struct = (struct meson_uart_struct *)cur_s;
				co_struct->s = cur_s + struct_size;
				co_struct->count = DEFAULT_STR_LEN;
				co_struct->co = co;
				co_struct->offset = 0;
				cur_col = &cur_col_list[index];
				cur_col->co_tail = co_struct;
				if (!cur_col->co_head)
					cur_col->co_head = co_struct;

				cur_col->user_count++;
				cur_col_management.user_count++;
				memcpy((char *)(co_struct->s),
					DEFAULT_STR, DEFAULT_STR_LEN);
				s = co_struct->s;
				*((char *)s + DEFAULT_STR_LEN-1) = '\n';

				list_add(&co_struct->list,
					&cur_col_management.list_head);
				last_msg_full = 1;
			}
		}


		cur_col = &cur_col_list[index];
		if (cur_col->co_head) {
			co_struct = cur_col->co_head;
			s = co_struct->s + co_struct->offset;
			if (index != meson_uart_console_index)
				meson_serial_console_setup(co, NULL);

			while ((readl(port->membase + AML_UART_CONTROL)
				& AML_UART_TX_EN)
				&& (!(readl(port->membase + AML_UART_STATUS)
				& AML_UART_TX_FULL))) {
				if (co_struct->count <= 0) {
					get_next_node(cur_col,
						co_struct, index);
					if (!cur_col->co_head)
						break;
					co_struct = cur_col->co_head;
					s = co_struct->s + co_struct->offset;
				}
				if (*s == '\n')
					writel('\r', port->membase
					+ AML_UART_WFIFO);
				writel(*s++, port->membase + AML_UART_WFIFO);
				co_struct->count--;
				co_struct->offset++;
			}

		}

	}
	spin_unlock_irqrestore(&cur_col_management.lock, flags);

}

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_MAX)
		return -EINVAL;

	meson_uart_console_index = (int)co->index;

	port = &meson_ports[co->index]->port;
	if (!port || !port->membase)
		return -ENODEV;

	if (options)
		uart_parse_options(options, &baud, &parity, &bits, &flow);

	return uart_set_options(port, co, baud, parity, bits, flow);
}

static void meson_early_write(struct console *con, const char *s,
	unsigned int n)
{
	struct earlycon_device *dev = con->data;

	uart_console_write(&dev->port, s, n, meson_console_putchar);
}

static int __init meson_early_console_setup(struct earlycon_device *device,
					    const char *opt)
{
	if (!device->port.membase)
		return -ENODEV;

	device->con->write = meson_early_write;
	return 0;
}
EARLYCON_DECLARE(aml_uart, meson_early_console_setup);

static struct console meson_serial_console = {
	.name = AML_UART_DEV_NAME,
	.write = meson_serial_console_write,
	.device = uart_console_device,
	.setup = meson_serial_console_setup,
	.flags = CON_PRINTBUFFER,
	.index = -1,
	.data = &meson_uart_driver,
};

static int __init meson_serial_console_init(void)
{
	register_console(&meson_serial_console);
	return 0;
}

console_initcall(meson_serial_console_init);

#define MESON_SERIAL_CONSOLE	(&meson_serial_console)
#else
#define MESON_SERIAL_CONSOLE	NULL
#endif

static struct uart_driver meson_uart_driver = {
	.owner = THIS_MODULE,
	.driver_name = "meson_uart",
	.dev_name = AML_UART_DEV_NAME,
	.nr = AML_UART_PORT_MAX,
	.cons = MESON_SERIAL_CONSOLE,
};

#ifdef CONFIG_HIBERNATION
static u32 save_mode;

static int meson_uart_freeze(struct device *dev)
{
	struct platform_device *pdev;
	struct uart_port *port;

	pdev = to_platform_device(dev);
	port = platform_get_drvdata(pdev);

	save_mode = readl(port->membase + AML_UART_CONTROL);

	pr_debug("uart freeze, mode: %x\n", save_mode);

	return 0;
}

static int meson_uart_thaw(struct device *dev)
{
	return 0;
}

static int meson_uart_restore(struct device *dev)
{
	struct platform_device *pdev;
	struct uart_port *port;

	pdev = to_platform_device(dev);
	port = platform_get_drvdata(pdev);

	writel(save_mode, port->membase + AML_UART_CONTROL);
	pr_debug("uart restore, mode: %x\n", save_mode);
	return 0;
}

static int meson_uart_suspend(struct platform_device *pdev,
	pm_message_t state);
static int meson_uart_resume(struct platform_device *pdev);
static int meson_uart_pm_suspend(struct device *dev)
{
	struct platform_device *pdev = to_platform_device(dev);

	return meson_uart_suspend(pdev, PMSG_SUSPEND);

}
static int meson_uart_pm_resume(struct device *dev)
{
	struct platform_device *pdev = to_platform_device(dev);

	return meson_uart_resume(pdev);
}
const struct dev_pm_ops meson_uart_pm = {
	.freeze		= meson_uart_freeze,
	.thaw		= meson_uart_thaw,
	.restore	= meson_uart_restore,
	.suspend	= meson_uart_pm_suspend,
	.resume		= meson_uart_pm_resume,
};
#endif

static int meson_uart_probe(struct platform_device *pdev)
{
	struct resource *res_mem, *res_irq;
	struct uart_port *port;
	struct meson_uart_port *mup;
	struct clk *clk;
	const void *prop;
	int ret = 0;

	if (pdev->dev.of_node)
		pdev->id = of_alias_get_id(pdev->dev.of_node, "serial");

	if (pdev->id < 0 || pdev->id >= AML_UART_PORT_MAX)
		return -EINVAL;

	res_mem = platform_get_resource(pdev, IORESOURCE_MEM, 0);
	if (!res_mem)
		return -ENODEV;

	res_irq = platform_get_resource(pdev, IORESOURCE_IRQ, 0);
	if (!res_irq)
		return -ENODEV;

	if (meson_ports[pdev->id]) {
		dev_err(&pdev->dev, "port %d already allocated\n", pdev->id);
		return -EBUSY;
	}

	mup = devm_kzalloc(&pdev->dev,
		sizeof(struct meson_uart_port), GFP_KERNEL);
	if (!mup)
		return -ENOMEM;

	spin_lock_init(&mup->wr_lock);
	port = &mup->port;
#ifdef CONFIG_AMLOGIC_CLK
	clk = devm_clk_get(&pdev->dev, "clk_gate");
	if (IS_ERR(clk)) {
		pr_err("%s: clock gate not found\n", dev_name(&pdev->dev));
		/* return PTR_ERR(clk); */
	} else {
		ret = clk_prepare_enable(clk);
		if (ret) {
			pr_err("uart: clock failed to prepare+enable: %d\n",
				ret);
			clk_put(clk);
			/* return ret; */
		}
	}

	clk = devm_clk_get(&pdev->dev, "clk_uart");
	if (IS_ERR(clk)) {
		pr_err("%s: clock source not found\n", dev_name(&pdev->dev));
		/* return PTR_ERR(clk); */
	}
	if (!IS_ERR(clk))
		port->uartclk = clk_get_rate(clk);
#endif

	port->fifosize = 64;
	prop = of_get_property(pdev->dev.of_node, "fifosize", NULL);
	if (prop)
		port->fifosize = of_read_ulong(prop, 1);

	if (!xtal_tick_en) {
		prop = of_get_property(pdev->dev.of_node, "xtal_tick_en", NULL);
		if (prop) {
			xtal_tick_en = of_read_ulong(prop, 1);
			if (xtal_tick_en == 1)
				xtal_tick_en = 0;
		}
	}

	port->iotype = UPIO_MEM;
	port->mapbase = res_mem->start;
	port->irq = res_irq->start;
	port->flags = UPF_BOOT_AUTOCONF | UPF_IOREMAP | UPF_LOW_LATENCY;
	port->dev = &pdev->dev;
	port->line = pdev->id;
	port->type = PORT_MESON;
	port->x_char = 0;
	port->ops = &meson_uart_ops;

	meson_ports[pdev->id] = mup;
	platform_set_drvdata(pdev, port);
	if (of_get_property(pdev->dev.of_node, "pinctrl-names", NULL)) {
		mup->p = devm_pinctrl_get_select_default(&pdev->dev);
		/* if (!mup->p) */
		/* return -1; */
	}
	ret = uart_add_one_port(&meson_uart_driver, port);
	if (ret)
		meson_ports[pdev->id] = NULL;

	prop = of_get_property(pdev->dev.of_node, "support-sysrq", NULL);
	if (prop)
		support_sysrq = of_read_ulong(prop, 1);

	return ret;
}

static int meson_uart_remove(struct platform_device *pdev)
{
	struct uart_port *port;

	port = platform_get_drvdata(pdev);
	uart_remove_one_port(&meson_uart_driver, port);
	meson_ports[pdev->id] = NULL;

	return 0;
}

static int meson_uart_resume(struct platform_device *pdev)
{
	struct uart_port *port;
	u32 val;

	port = platform_get_drvdata(pdev);
	if (!port) {
		dev_err(&pdev->dev, "port is NULL");
		return 0;
	}

	if (port->line == 0)
		return 0;
	uart_resume_port(&meson_uart_driver, port);

	val = readl(port->membase + AML_UART_CONTROL);
	if (!(val & AML_UART_TWO_WIRE_EN)) {
		val &= ~(0x1 << 31);
		writel(val, port->membase + AML_UART_CONTROL);
	}

	return 0;
}

static int meson_uart_suspend(struct platform_device *pdev,
	pm_message_t state)
{
	struct uart_port *port;
	u32 val;

	port = platform_get_drvdata(pdev);
	if (!port) {
		dev_err(&pdev->dev, "port is NULL");
		return 0;
	}

	if (port->line == 0)
		return 0;
	uart_suspend_port(&meson_uart_driver, port);

	val = readl(port->membase + AML_UART_CONTROL);
	/* if rts/cts is open, pull up rts pin
	 * when in suspend
	 */
	if (!(val & AML_UART_TWO_WIRE_EN)) {
		dev_info(&pdev->dev, "pull up rts");
		val |= (0x1 << 31);
		writel(val, port->membase + AML_UART_CONTROL);
	}

	return 0;
}

static const struct of_device_id meson_uart_dt_match[] = {
	{.compatible = "amlogic, meson-uart"},
	{ /* 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,
	.suspend	= meson_uart_suspend,
	.resume		= meson_uart_resume,
	.driver = {
		   .owner = THIS_MODULE,
		   .name = "meson_uart",
		   .of_match_table = meson_uart_dt_match,
#ifdef CONFIG_HIBERNATION
		   .pm = &meson_uart_pm,
#endif
		   },
};

static int __init meson_uart_init(void)
{
	int ret;

	ret = uart_register_driver(&meson_uart_driver);
	if (ret)
		return ret;

	ret = platform_driver_register(&meson_uart_platform_driver);
	if (ret) {
		uart_unregister_driver(&meson_uart_driver);
		return ret;
	}

	ret = driver_create_file(&meson_uart_platform_driver.driver,
		&driver_attr_printkmode);

	ret = driver_create_file(&meson_uart_platform_driver.driver,
		&driver_attr_sysrqsupport);

	INIT_LIST_HEAD(&cur_col_management.list_head);
	spin_lock_init(&cur_col_management.lock);
	data_cache = vmalloc(MESON_SERIAL_BUFFER_SIZE);
	if (!data_cache) {
		pr_info("buffer alloc failed for uart\n");
		platform_driver_unregister(&meson_uart_platform_driver);
		uart_unregister_driver(&meson_uart_driver);
		return -ENOMEM;
	}

	return ret;
}

static void __exit meson_uart_exit(void)
{
	platform_driver_unregister(&meson_uart_platform_driver);
	uart_unregister_driver(&meson_uart_driver);
}

module_init(meson_uart_init);
module_exit(meson_uart_exit);

MODULE_AUTHOR("Carlo Caione <carlo@caione.org>");
MODULE_DESCRIPTION("Amlogic Meson serial port driver");
MODULE_LICENSE("GPL v2");