path: root/drivers/tty/serial/ar933x_uart.c

// SPDX-License-Identifier: GPL-2.0
/*
 *  Atheros AR933X SoC built-in UART driver
 *
 *  Copyright (C) 2011 Gabor Juhos <juhosg@openwrt.org>
 *
 *  Based on drivers/char/serial.c, by Linus Torvalds, Theodore Ts'o.
 */

#include <linux/module.h>
#include <linux/ioport.h>
#include <linux/init.h>
#include <linux/console.h>
#include <linux/sysrq.h>
#include <linux/delay.h>
#include <linux/gpio/consumer.h>
#include <linux/platform_device.h>
#include <linux/of.h>
#include <linux/of_platform.h>
#include <linux/tty.h>
#include <linux/tty_flip.h>
#include <linux/serial_core.h>
#include <linux/serial.h>
#include <linux/slab.h>
#include <linux/io.h>
#include <linux/irq.h>
#include <linux/clk.h>

#include <asm/div64.h>

#include <asm/mach-ath79/ar933x_uart.h>

#include "serial_mctrl_gpio.h"

#define DRIVER_NAME "ar933x-uart"

#define AR933X_UART_MAX_SCALE	0xff
#define AR933X_UART_MAX_STEP	0xffff

#define AR933X_UART_MIN_BAUD	300
#define AR933X_UART_MAX_BAUD	3000000

#define AR933X_DUMMY_STATUS_RD	0x01

static struct uart_driver ar933x_uart_driver;

struct ar933x_uart_port {
	struct uart_port	port;
	unsigned int		ier;	/* shadow Interrupt Enable Register */
	unsigned int		min_baud;
	unsigned int		max_baud;
	struct clk		*clk;
	struct mctrl_gpios	*gpios;
	struct gpio_desc	*rts_gpiod;
};

static inline unsigned int ar933x_uart_read(struct ar933x_uart_port *up,
					    int offset)
{
	return readl(up->port.membase + offset);
}

static inline void ar933x_uart_write(struct ar933x_uart_port *up,
				     int offset, unsigned int value)
{
	writel(value, up->port.membase + offset);
}

static inline void ar933x_uart_rmw(struct ar933x_uart_port *up,
				  unsigned int offset,
				  unsigned int mask,
				  unsigned int val)
{
	unsigned int t;

	t = ar933x_uart_read(up, offset);
	t &= ~mask;
	t |= val;
	ar933x_uart_write(up, offset, t);
}

static inline void ar933x_uart_rmw_set(struct ar933x_uart_port *up,
				       unsigned int offset,
				       unsigned int val)
{
	ar933x_uart_rmw(up, offset, 0, val);
}

static inline void ar933x_uart_rmw_clear(struct ar933x_uart_port *up,
					 unsigned int offset,
					 unsigned int val)
{
	ar933x_uart_rmw(up, offset, val, 0);
}

static inline void ar933x_uart_start_tx_interrupt(struct ar933x_uart_port *up)
{
	up->ier |= AR933X_UART_INT_TX_EMPTY;
	ar933x_uart_write(up, AR933X_UART_INT_EN_REG, up->ier);
}

static inline void ar933x_uart_stop_tx_interrupt(struct ar933x_uart_port *up)
{
	up->ier &= ~AR933X_UART_INT_TX_EMPTY;
	ar933x_uart_write(up, AR933X_UART_INT_EN_REG, up->ier);
}

static inline void ar933x_uart_start_rx_interrupt(struct ar933x_uart_port *up)
{
	up->ier |= AR933X_UART_INT_RX_VALID;
	ar933x_uart_write(up, AR933X_UART_INT_EN_REG, up->ier);
}

static inline void ar933x_uart_stop_rx_interrupt(struct ar933x_uart_port *up)
{
	up->ier &= ~AR933X_UART_INT_RX_VALID;
	ar933x_uart_write(up, AR933X_UART_INT_EN_REG, up->ier);
}

static inline void ar933x_uart_putc(struct ar933x_uart_port *up, int ch)
{
	unsigned int rdata;

	rdata = ch & AR933X_UART_DATA_TX_RX_MASK;
	rdata |= AR933X_UART_DATA_TX_CSR;
	ar933x_uart_write(up, AR933X_UART_DATA_REG, rdata);
}

static unsigned int ar933x_uart_tx_empty(struct uart_port *port)
{
	struct ar933x_uart_port *up =
		container_of(port, struct ar933x_uart_port, port);
	unsigned long flags;
	unsigned int rdata;

	uart_port_lock_irqsave(&up->port, &flags);
	rdata = ar933x_uart_read(up, AR933X_UART_DATA_REG);
	uart_port_unlock_irqrestore(&up->port, flags);

	return (rdata & AR933X_UART_DATA_TX_CSR) ? 0 : TIOCSER_TEMT;
}

static unsigned int ar933x_uart_get_mctrl(struct uart_port *port)
{
	struct ar933x_uart_port *up =
		container_of(port, struct ar933x_uart_port, port);
	int ret = TIOCM_CTS | TIOCM_DSR | TIOCM_CAR;

	mctrl_gpio_get(up->gpios, &ret);

	return ret;
}

static void ar933x_uart_set_mctrl(struct uart_port *port, unsigned int mctrl)
{
	struct ar933x_uart_port *up =
		container_of(port, struct ar933x_uart_port, port);

	mctrl_gpio_set(up->gpios, mctrl);
}

static void ar933x_uart_start_tx(struct uart_port *port)