// 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)
{
        struct ar933x_uart_port *up =
                container_of(port, struct ar933x_uart_port, port);

        ar933x_uart_start_tx_interrupt(up);
}

static void ar933x_uart_wait_tx_complete(struct ar933x_uart_port *up)
{
        unsigned int status;
        unsigned int timeout = 60000;

        /* Wait up to 60ms for the character(s) to be sent. */
        do {
                status = ar933x_uart_read(up, AR933X_UART_CS_REG);
                if (--timeout == 0)
                        break;
                udelay(1);
        } while (status & AR933X_UART_CS_TX_BUSY);

        if (timeout == 0)
                dev_err(up->port.dev, "waiting for TX timed out\n");
}

static void ar933x_uart_rx_flush(struct ar933x_uart_port *up)
{
        unsigned int status;

        /* clear RX_VALID interrupt */
        ar933x_uart_write(up, AR933X_UART_INT_REG, AR933X_UART_INT_RX_VALID);

        /* remove characters from the RX FIFO */
        do {
                ar933x_uart_write(up, AR933X_UART_DATA_REG, AR933X_UART_DATA_RX_CSR);
                status = ar933x_uart_read(up, AR933X_UART_DATA_REG);
        } while (status & AR933X_UART_DATA_RX_CSR);
}

static void ar933x_uart_stop_tx(struct uart_port *port)
{
        struct ar933x_uart_port *up =
                container_of(port, struct ar933x_uart_port, port);

        ar933x_uart_stop_tx_interrupt(up);
}

static void ar933x_uart_stop_rx(struct uart_port *port)
{
        struct ar933x_uart_port *up =
                container_of(port, struct ar933x_uart_port, port);

        ar933x_uart_stop_rx_interrupt(up);
}

static void ar933x_uart_break_ctl(struct uart_port *port, int break_state)
{
        struct ar933x_uart_port *up =
                container_of(port, struct ar933x_uart_port, port);
        unsigned long flags;

        uart_port_lock_irqsave(&up->port, &flags);
        if (break_state == -1)
                ar933x_uart_rmw_set(up, AR933X_UART_CS_REG,
                                    AR933X_UART_CS_TX_BREAK);
        else
                ar933x_uart_rmw_clear(up, AR933X_UART_CS_REG,
                                      AR933X_UART_CS_TX_BREAK);
        uart_port_unlock_irqrestore(&up->port, flags);
}

/*
 * baudrate = (clk / (scale + 1)) * (step * (1 / 2^17))
 */
static unsigned long ar933x_uart_get_baud(unsigned int clk,
                                          unsigned int scale,
                                          unsigned int step)
{
        u64 t;
        u32 div;

        div = (2 << 16) * (scale + 1);
        t = clk;
        t *= step;
        t += (div / 2);
        do_div(t, div);

        return t;
}

static void ar933x_uart_get_scale_step(unsigned int clk,
                                       unsigned int baud,
                                       unsigned int *scale,
                                       unsigned int *step)
{
        unsigned int tscale;
        long min_diff;

        *scale = 0;
        *step = 0;

        min_diff = baud;
        for (tscale = 0; tscale < AR933X_UART_MAX_SCALE; tscale++) {
                u64 tstep;
                int diff;

                tstep = baud * (tscale + 1);
                tstep *= (2 << 16);
                do_div(tstep, clk);

                if (tstep > AR933X_UART_MAX_STEP)
                        break;

                diff = abs(ar933x_uart_get_baud(clk, tscale, tstep) - baud);
                if (diff < min_diff) {
                        min_diff = diff;
                        *scale = tscale;
                        *step = tstep;
                }
        }
}

static void ar933x_uart_set_termios(struct uart_port *port,
                                    struct ktermios *new,
                                    const struct ktermios *old)
{
        struct ar933x_uart_port *up =
                container_of(port, struct ar933x_uart_port, port);
        unsigned int cs;
        unsigned long flags;
        unsigned int baud, scale, step;

        /* Only CS8 is supported */
        new->c_cflag &= ~CSIZE;
        new->c_cflag |= CS8;

        /* Only one stop bit is supported */
        new->c_cflag &= ~CSTOPB;

        cs = 0;
        if (new->c_cflag & PARENB) {
                if (!(new->c_cflag & PARODD))
                        cs |= AR933X_UART_CS_PARITY_EVEN;
                else
                        cs |= AR933X_UART_CS_PARITY_ODD;
        } else {
                cs |= AR933X_UART_CS_PARITY_NONE;
        }

        /* Mark/space parity is not supported */
        new->c_cflag &= ~CMSPAR;

        baud = uart_get_baud_rate(port, new, old, up->min_baud, up->max_baud);
        ar933x_uart_get_scale_step(port->uartclk, baud, &scale, &step);

        /*
         * Ok, we're now changing the port state. Do it with
         * interrupts disabled.
         */
        uart_port_lock_irqsave(&up->port, &flags);

        /* disable the UART */
        ar933x_uart_rmw_clear(up, AR933X_UART_CS_REG,
                      AR933X_UART_CS_IF_MODE_M << AR933X_UART_CS_IF_MODE_S);

        /* Update the per-port timeout. */
        uart_update_timeout(port, new->c_cflag, baud);

        up->port.ignore_status_mask = 0;

        /* ignore all characters if CREAD is not set */
        if ((new->c_cflag & CREAD) == 0)
                up->port.ignore_status_mask |= AR933X_DUMMY_STATUS_RD;

        ar933x_uart_write(up, AR933X_UART_CLOCK_REG,
                          scale << AR933X_UART_CLOCK_SCALE_S | step);

        /* setup configuration register */
        ar933x_uart_rmw(up, AR933X_UART_CS_REG, AR933X_UART_CS_PARITY_M, cs);

        /* enable host interrupt */
        ar933x_uart_rmw_set(up, AR933X_UART_CS_REG,
                            AR933X_UART_CS_HOST_INT_EN);

        /* enable RX and TX ready overide */
        ar933x_uart_rmw_set(up, AR933X_UART_CS_REG,
                AR933X_UART_CS_TX_READY_ORIDE | AR933X_UART_CS_RX_READY_ORIDE);

        /* reenable the UART */
        ar933x_uart_rmw(up, AR933X_UART_CS_REG,
                        AR933X_UART_CS_IF_MODE_M << AR933X_UART_CS_IF_MODE_S,
                        AR933X_UART_CS_IF_MODE_DCE << AR933X_UART_CS_IF_MODE_S);

        uart_port_unlock_irqrestore(&up->port, flags);

        if (tty_termios_baud_rate(new))
                tty_termios_encode_baud_rate(new, baud, baud);
}

static void ar933x_uart_rx_chars(struct ar933x_uart_port *up)
{
        struct tty_port *port = &up->port.state->port;
        int max_count = 256;

        do {
                unsigned int rdata;
                unsigned char ch;

                rdata = ar933x_uart_read(up, AR933X_UART_DATA_REG);
                if ((rdata & AR933X_UART_DATA_RX_CSR) == 0)
                        break;

                /* remove the character from the FIFO */
                ar933x_uart_write(up, AR933X_UART_DATA_REG,
                                  AR933X_UART_DATA_RX_CSR);

                up->port.icount.rx++;
                ch = rdata & AR933X_UART_DATA_TX_RX_MASK;

                if (uart_prepare_sysrq_char(&up->port, ch))
                        continue;

                if ((up->port.ignore_status_mask & AR933X_DUMMY_STATUS_RD) == 0)
                        tty_insert_flip_char(port, ch, TTY_NORMAL);
        } while (max_count-- > 0);

        tty_flip_buffer_push(port);
}

static void ar933x_uart_tx_chars(struct ar933x_uart_port *up)
{
        struct tty_port *tport = &up->port.state->port;
        struct serial_rs485 *rs485conf = &up->port.rs485;
        int count;
        bool half_duplex_send = false;

        if (uart_tx_stopped(&up->port))
                return;

        if ((rs485conf->flags & SER_RS485_ENABLED) &&
            (up->port.x_char || !kfifo_is_empty(&tport->xmit_fifo))) {
                ar933x_uart_stop_rx_interrupt(up);
                gpiod_set_value(up->rts_gpiod, !!(rs485conf->flags & SER_RS485_RTS_ON_SEND));
                half_duplex_send = true;
        }

        count = up->port.fifosize;
        do {
                unsigned int rdata;
                unsigned char c;

                rdata = ar933x_uart_read(up, AR933X_UART_DATA_REG);
                if ((rdata & AR933X_UART_DATA_TX_CSR) == 0)
                        break;

                if (up->port.x_char) {
                        ar933x_uart_putc(up, up->port.x_char);
                        up->port.icount.tx++;
                        up->port.x_char = 0;
                        continue;
                }

                if (!uart_fifo_get(&up->port, &c))
                        break;

                ar933x_uart_putc(up, c);
        } while (--count > 0);

        if (kfifo_len(&tport->xmit_fifo) < WAKEUP_CHARS)
                uart_write_wakeup(&up->port);

        if (!kfifo_is_empty(&tport->xmit_fifo)) {
                ar933x_uart_start_tx_interrupt(up);
        } else if (half_duplex_send) {
                ar933x_uart_wait_tx_complete(up);
                ar933x_uart_rx_flush(up);
                ar933x_uart_start_rx_interrupt(up);
                gpiod_set_value(up->rts_gpiod, !!(rs485conf->flags & SER_RS485_RTS_AFTER_SEND));
        }
}

static irqreturn_t ar933x_uart_interrupt(int irq, void *dev_id)
{
        struct ar933x_uart_port *up = dev_id;
        unsigned int status;

        status = ar933x_uart_read(up, AR933X_UART_CS_REG);
        if ((status & AR933X_UART_CS_HOST_INT) == 0)
                return IRQ_NONE;

        uart_port_lock(&up->port);

        status = ar933x_uart_read(up, AR933X_UART_INT_REG);
        status &= ar933x_uart_read(up, AR933X_UART_INT_EN_REG);

        if (status & AR933X_UART_INT_RX_VALID) {
                ar933x_uart_write(up, AR933X_UART_INT_REG,
                                  AR933X_UART_INT_RX_VALID);
                ar933x_uart_rx_chars(up);
        }

        if (status & AR933X_UART_INT_TX_EMPTY) {
                ar933x_uart_write(up, AR933X_UART_INT_REG,
                                  AR933X_UART_INT_TX_EMPTY);
                ar933x_uart_stop_tx_interrupt(up);
                ar933x_uart_tx_chars(up);
        }

        uart_unlock_and_check_sysrq(&up->port);

        return IRQ_HANDLED;
}

static int ar933x_uart_startup(struct uart_port *port)
{
        struct ar933x_uart_port *up =
                container_of(port, struct ar933x_uart_port, port);
        unsigned long flags;
        int ret;

        ret = request_irq(up->port.irq, ar933x_uart_interrupt,
                          up->port.irqflags, dev_name(up->port.dev), up);
        if (ret)
                return ret;

        uart_port_lock_irqsave(&up->port, &flags);

        /* Enable HOST interrupts */
        ar933x_uart_rmw_set(up, AR933X_UART_CS_REG,
                            AR933X_UART_CS_HOST_INT_EN);

        /* enable RX and TX ready overide */
        ar933x_uart_rmw_set(up, AR933X_UART_CS_REG,
                AR933X_UART_CS_TX_READY_ORIDE | AR933X_UART_CS_RX_READY_ORIDE);

        /* Enable RX interrupts */
        ar933x_uart_start_rx_interrupt(up);

        uart_port_unlock_irqrestore(&up->port, flags);

        return 0;
}

static void ar933x_uart_shutdown(struct uart_port *port)
{
        struct ar933x_uart_port *up =
                container_of(port, struct ar933x_uart_port, port);

        /* Disable all interrupts */
        up->ier = 0;
        ar933x_uart_write(up, AR933X_UART_INT_EN_REG, up->ier);

        /* Disable break condition */
        ar933x_uart_rmw_clear(up, AR933X_UART_CS_REG,
                              AR933X_UART_CS_TX_BREAK);

        free_irq(up->port.irq, up);
}

static const char *ar933x_uart_type(struct uart_port *port)
{
        return (port->type == PORT_AR933X) ? "AR933X UART" : NULL;
}

static void ar933x_uart_release_port(struct uart_port *port)
{
        /* Nothing to release ... */
}

static int ar933x_uart_request_port(struct uart_port *port)
{
        /* UARTs always present */
        return 0;
}

static void ar933x_uart_config_port(struct uart_port *port, int flags)
{
        if (flags & UART_CONFIG_TYPE)
                port->type = PORT_AR933X;
}

static int ar933x_uart_verify_port(struct uart_port *port,
                                   struct serial_struct *ser)
{
        struct ar933x_uart_port *up =
                container_of(port, struct ar933x_uart_port, port);

        if (ser->type != PORT_UNKNOWN &&
            ser->type != PORT_AR933X)
                return -EINVAL;

        if (ser->irq < 0 || ser->irq >= NR_IRQS)
                return -EINVAL;

        if (ser->baud_base < up->min_baud ||
            ser->baud_base > up->max_baud)
                return -EINVAL;

        return 0;
}

#ifdef CONFIG_CONSOLE_POLL
static int ar933x_poll_get_char(struct uart_port *port)
{
        struct ar933x_uart_port *up =
                container_of(port, struct ar933x_uart_port, port);
        unsigned int rdata;
        unsigned char ch;
        u32 imr;

        /* Disable all interrupts */
        imr = ar933x_uart_read(up, AR933X_UART_INT_EN_REG);
        ar933x_uart_write(up, AR933X_UART_INT_EN_REG, 0);

        rdata = ar933x_uart_read(up, AR933X_UART_DATA_REG);
        if ((rdata & AR933X_UART_DATA_RX_CSR) == 0) {
                /* Enable interrupts */
                ar933x_uart_write(up, AR933X_UART_INT_EN_REG, imr);
                return NO_POLL_CHAR;
        }

        /* remove the character from the FIFO */
        ar933x_uart_write(up, AR933X_UART_DATA_REG,
                          AR933X_UART_DATA_RX_CSR);

        ch = rdata & AR933X_UART_DATA_TX_RX_MASK;

        /* Enable interrupts */
        ar933x_uart_write(up, AR933X_UART_INT_EN_REG, imr);

        return ch;
}

static void ar933x_poll_put_char(struct uart_port *port, unsigned char c)
{
        struct ar933x_uart_port *up =
                container_of(port, struct ar933x_uart_port, port);
        u32 imr;

        /* Disable all interrupts */
        imr = ar933x_uart_read(up, AR933X_UART_INT_EN_REG);
        ar933x_uart_write(up, AR933X_UART_INT_EN_REG, 0);

        /* Wait until FIFO is empty */
        while (!(ar933x_uart_read(up, AR933X_UART_DATA_REG) & AR933X_UART_DATA_TX_CSR))
                cpu_relax();

        /* Write a character */
        ar933x_uart_putc(up, c);

        /* Wait until FIFO is empty */
        while (!(ar933x_uart_read(up, AR933X_UART_DATA_REG) & AR933X_UART_DATA_TX_CSR))
                cpu_relax();

        /* Enable interrupts */
        ar933x_uart_write(up, AR933X_UART_INT_EN_REG, imr);
}
#endif

static const struct uart_ops ar933x_uart_ops = {
        .tx_empty       = ar933x_uart_tx_empty,
        .set_mctrl      = ar933x_uart_set_mctrl,
        .get_mctrl      = ar933x_uart_get_mctrl,
        .stop_tx        = ar933x_uart_stop_tx,
        .start_tx       = ar933x_uart_start_tx,
        .stop_rx        = ar933x_uart_stop_rx,
        .break_ctl      = ar933x_uart_break_ctl,
        .startup        = ar933x_uart_startup,
        .shutdown       = ar933x_uart_shutdown,
        .set_termios    = ar933x_uart_set_termios,
        .type           = ar933x_uart_type,
        .release_port   = ar933x_uart_release_port,
        .request_port   = ar933x_uart_request_port,
        .config_port    = ar933x_uart_config_port,
        .verify_port    = ar933x_uart_verify_port,
#ifdef CONFIG_CONSOLE_POLL
        .poll_get_char  = ar933x_poll_get_char,
        .poll_put_char  = ar933x_poll_put_char,
#endif
};

static int ar933x_config_rs485(struct uart_port *port, struct ktermios *termios,
                                struct serial_rs485 *rs485conf)
{
        struct ar933x_uart_port *up =
                        container_of(port, struct ar933x_uart_port, port);

        if (port->rs485.flags & SER_RS485_ENABLED)
                gpiod_set_value(up->rts_gpiod,
                        !!(rs485conf->flags & SER_RS485_RTS_AFTER_SEND));

        return 0;
}

#ifdef CONFIG_SERIAL_AR933X_CONSOLE
static struct ar933x_uart_port *
ar933x_console_ports[CONFIG_SERIAL_AR933X_NR_UARTS];

static void ar933x_uart_wait_xmitr(struct ar933x_uart_port *up)
{
        unsigned int status;
        unsigned int timeout = 60000;

        /* Wait up to 60ms for the character(s) to be sent. */
        do {
                status = ar933x_uart_read(up, AR933X_UART_DATA_REG);
                if (--timeout == 0)
                        break;
                udelay(1);
        } while ((status & AR933X_UART_DATA_TX_CSR) == 0);
}

static void ar933x_uart_console_putchar(struct uart_port *port, unsigned char ch)
{
        struct ar933x_uart_port *up =
                container_of(port, struct ar933x_uart_port, port);

        ar933x_uart_wait_xmitr(up);
        ar933x_uart_putc(up, ch);
}

static void ar933x_uart_console_write(struct console *co, const char *s,
                                      unsigned int count)
{
        struct ar933x_uart_port *up = ar933x_console_ports[co->index];
        unsigned long flags;
        unsigned int int_en;
        int locked = 1;

        if (oops_in_progress)
                locked = uart_port_trylock_irqsave(&up->port, &flags);
        else
                uart_port_lock_irqsave(&up->port, &flags);

        /*
         * First save the IER then disable the interrupts
         */
        int_en = ar933x_uart_read(up, AR933X_UART_INT_EN_REG);
        ar933x_uart_write(up, AR933X_UART_INT_EN_REG, 0);

        uart_console_write(&up->port, s, count, ar933x_uart_console_putchar);

        /*
         * Finally, wait for transmitter to become empty
         * and restore the IER
         */
        ar933x_uart_wait_xmitr(up);
        ar933x_uart_write(up, AR933X_UART_INT_EN_REG, int_en);

        ar933x_uart_write(up, AR933X_UART_INT_REG, AR933X_UART_INT_ALLINTS);

        if (locked)
                uart_port_unlock_irqrestore(&up->port, flags);
}

static int ar933x_uart_console_setup(struct console *co, char *options)
{
        struct ar933x_uart_port *up;
        int baud = 115200;
        int bits = 8;
        int parity = 'n';
        int flow = 'n';

        if (co->index < 0 || co->index >= CONFIG_SERIAL_AR933X_NR_UARTS)
                return -EINVAL;

        up = ar933x_console_ports[co->index];
        if (!up)
                return -ENODEV;

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

        return uart_set_options(&up->port, co, baud, parity, bits, flow);
}

static struct console ar933x_uart_console = {
        .name           = "ttyATH",
        .write          = ar933x_uart_console_write,
        .device         = uart_console_device,
        .setup          = ar933x_uart_console_setup,
        .flags          = CON_PRINTBUFFER,
        .index          = -1,
        .data           = &ar933x_uart_driver,
};
#endif /* CONFIG_SERIAL_AR933X_CONSOLE */

static struct uart_driver ar933x_uart_driver = {
        .owner          = THIS_MODULE,
        .driver_name    = DRIVER_NAME,
        .dev_name       = "ttyATH",
        .nr             = CONFIG_SERIAL_AR933X_NR_UARTS,
        .cons           = NULL, /* filled in runtime */
};

static const struct serial_rs485 ar933x_rs485_supported = {
        .flags = SER_RS485_ENABLED | SER_RS485_RTS_ON_SEND | SER_RS485_RTS_AFTER_SEND,
};

static int ar933x_uart_probe(struct platform_device *pdev)
{
        struct ar933x_uart_port *up;
        struct uart_port *port;
        struct resource *mem_res;
        struct device_node *np;
        unsigned int baud;
        int id;
        int ret;
        int irq;

        np = pdev->dev.of_node;
        if (IS_ENABLED(CONFIG_OF) && np) {
                id = of_alias_get_id(np, "serial");
                if (id < 0) {
                        dev_err(&pdev->dev, "unable to get alias id, err=%d\n",
                                id);
                        return id;
                }
        } else {
                id = pdev->id;
                if (id == -1)
                        id = 0;
        }

        if (id >= CONFIG_SERIAL_AR933X_NR_UARTS)
                return -EINVAL;

        irq = platform_get_irq(pdev, 0);
        if (irq < 0)
                return irq;

        up = devm_kzalloc(&pdev->dev, sizeof(struct ar933x_uart_port),
                          GFP_KERNEL);
        if (!up)
                return -ENOMEM;

        up->clk = devm_clk_get(&pdev->dev, "uart");
        if (IS_ERR(up->clk)) {
                dev_err(&pdev->dev, "unable to get UART clock\n");
                return PTR_ERR(up->clk);
        }

        port = &up->port;

        port->membase = devm_platform_get_and_ioremap_resource(pdev, 0, &mem_res);
        if (IS_ERR(port->membase))
                return PTR_ERR(port->membase);

        ret = clk_prepare_enable(up->clk);
        if (ret)
                return ret;

        port->uartclk = clk_get_rate(up->clk);
        if (!port->uartclk) {
                ret = -EINVAL;
                goto err_disable_clk;
        }

        port->mapbase = mem_res->start;
        port->line = id;
        port->irq = irq;
        port->dev = &pdev->dev;
        port->type = PORT_AR933X;
        port->iotype = UPIO_MEM32;

        port->regshift = 2;
        port->fifosize = AR933X_UART_FIFO_SIZE;
        port->ops = &ar933x_uart_ops;
        port->rs485_config = ar933x_config_rs485;
        port->rs485_supported = ar933x_rs485_supported;

        baud = ar933x_uart_get_baud(port->uartclk, AR933X_UART_MAX_SCALE, 1);
        up->min_baud = max_t(unsigned int, baud, AR933X_UART_MIN_BAUD);

        baud = ar933x_uart_get_baud(port->uartclk, 0, AR933X_UART_MAX_STEP);
        up->max_baud = min_t(unsigned int, baud, AR933X_UART_MAX_BAUD);

        ret = uart_get_rs485_mode(port);
        if (ret)
                goto err_disable_clk;

        up->gpios = mctrl_gpio_init(port, 0);
        if (IS_ERR(up->gpios) && PTR_ERR(up->gpios) != -ENOSYS) {
                ret = PTR_ERR(up->gpios);
                goto err_disable_clk;
        }

        up->rts_gpiod = mctrl_gpio_to_gpiod(up->gpios, UART_GPIO_RTS);

        if (!up->rts_gpiod) {
                port->rs485_supported.flags &= ~SER_RS485_ENABLED;
                if (port->rs485.flags & SER_RS485_ENABLED) {
                        dev_err(&pdev->dev, "lacking rts-gpio, disabling RS485\n");
                        port->rs485.flags &= ~SER_RS485_ENABLED;
                }
        }

#ifdef CONFIG_SERIAL_AR933X_CONSOLE
        ar933x_console_ports[up->port.line] = up;
#endif

        ret = uart_add_one_port(&ar933x_uart_driver, &up->port);
        if (ret)
                goto err_disable_clk;

        platform_set_drvdata(pdev, up);
        return 0;

err_disable_clk:
        clk_disable_unprepare(up->clk);
        return ret;
}

static void ar933x_uart_remove(struct platform_device *pdev)
{
        struct ar933x_uart_port *up;

        up = platform_get_drvdata(pdev);

        if (up) {
                uart_remove_one_port(&ar933x_uart_driver, &up->port);
                clk_disable_unprepare(up->clk);
        }
}

#ifdef CONFIG_OF
static const struct of_device_id ar933x_uart_of_ids[] = {
        { .compatible = "qca,ar9330-uart" },
        {},
};
MODULE_DEVICE_TABLE(of, ar933x_uart_of_ids);
#endif

static struct platform_driver ar933x_uart_platform_driver = {
        .probe          = ar933x_uart_probe,
        .remove         = ar933x_uart_remove,
        .driver         = {
                .name           = DRIVER_NAME,
                .of_match_table = of_match_ptr(ar933x_uart_of_ids),
        },
};

static int __init ar933x_uart_init(void)
{
        int ret;

#ifdef CONFIG_SERIAL_AR933X_CONSOLE
        ar933x_uart_driver.cons = &ar933x_uart_console;
#endif

        ret = uart_register_driver(&ar933x_uart_driver);
        if (ret)
                goto err_out;

        ret = platform_driver_register(&ar933x_uart_platform_driver);
        if (ret)
                goto err_unregister_uart_driver;

        return 0;

err_unregister_uart_driver:
        uart_unregister_driver(&ar933x_uart_driver);
err_out:
        return ret;
}

static void __exit ar933x_uart_exit(void)
{
        platform_driver_unregister(&ar933x_uart_platform_driver);
        uart_unregister_driver(&ar933x_uart_driver);
}

module_init(ar933x_uart_init);
module_exit(ar933x_uart_exit);

MODULE_DESCRIPTION("Atheros AR933X UART driver");
MODULE_AUTHOR("Gabor Juhos <juhosg@openwrt.org>");
MODULE_LICENSE("GPL v2");
MODULE_ALIAS("platform:" DRIVER_NAME);