// SPDX-License-Identifier: GPL-2.0+
/*
 * RDA8810PL serial device driver
 *
 * Copyright RDA Microelectronics Company Limited
 * Copyright (c) 2017 Andreas Färber
 * Copyright (c) 2018 Manivannan Sadhasivam
 */

#include <linux/clk.h>
#include <linux/console.h>
#include <linux/delay.h>
#include <linux/io.h>
#include <linux/module.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>

#define RDA_UART_PORT_NUM 3
#define RDA_UART_DEV_NAME "ttyRDA"

#define RDA_UART_CTRL           0x00
#define RDA_UART_STATUS         0x04
#define RDA_UART_RXTX_BUFFER    0x08
#define RDA_UART_IRQ_MASK       0x0c
#define RDA_UART_IRQ_CAUSE      0x10
#define RDA_UART_IRQ_TRIGGERS   0x14
#define RDA_UART_CMD_SET        0x18
#define RDA_UART_CMD_CLR        0x1c

/* UART_CTRL Bits */
#define RDA_UART_ENABLE                 BIT(0)
#define RDA_UART_DBITS_8                BIT(1)
#define RDA_UART_TX_SBITS_2             BIT(2)
#define RDA_UART_PARITY_EN              BIT(3)
#define RDA_UART_PARITY(x)              (((x) & 0x3) << 4)
#define RDA_UART_PARITY_ODD             RDA_UART_PARITY(0)
#define RDA_UART_PARITY_EVEN            RDA_UART_PARITY(1)
#define RDA_UART_PARITY_SPACE           RDA_UART_PARITY(2)
#define RDA_UART_PARITY_MARK            RDA_UART_PARITY(3)
#define RDA_UART_DIV_MODE               BIT(20)
#define RDA_UART_IRDA_EN                BIT(21)
#define RDA_UART_DMA_EN                 BIT(22)
#define RDA_UART_FLOW_CNT_EN            BIT(23)
#define RDA_UART_LOOP_BACK_EN           BIT(24)
#define RDA_UART_RX_LOCK_ERR            BIT(25)
#define RDA_UART_RX_BREAK_LEN(x)        (((x) & 0xf) << 28)

/* UART_STATUS Bits */
#define RDA_UART_RX_FIFO(x)             (((x) & 0x7f) << 0)
#define RDA_UART_RX_FIFO_MASK           (0x7f << 0)
#define RDA_UART_TX_FIFO(x)             (((x) & 0x1f) << 8)
#define RDA_UART_TX_FIFO_MASK           (0x1f << 8)
#define RDA_UART_TX_ACTIVE              BIT(14)
#define RDA_UART_RX_ACTIVE              BIT(15)
#define RDA_UART_RX_OVERFLOW_ERR        BIT(16)
#define RDA_UART_TX_OVERFLOW_ERR        BIT(17)
#define RDA_UART_RX_PARITY_ERR          BIT(18)
#define RDA_UART_RX_FRAMING_ERR         BIT(19)
#define RDA_UART_RX_BREAK_INT           BIT(20)
#define RDA_UART_DCTS                   BIT(24)
#define RDA_UART_CTS                    BIT(25)
#define RDA_UART_DTR                    BIT(28)
#define RDA_UART_CLK_ENABLED            BIT(31)

/* UART_RXTX_BUFFER Bits */
#define RDA_UART_RX_DATA(x)             (((x) & 0xff) << 0)
#define RDA_UART_TX_DATA(x)             (((x) & 0xff) << 0)

/* UART_IRQ_MASK Bits */
#define RDA_UART_TX_MODEM_STATUS        BIT(0)
#define RDA_UART_RX_DATA_AVAILABLE      BIT(1)
#define RDA_UART_TX_DATA_NEEDED         BIT(2)
#define RDA_UART_RX_TIMEOUT             BIT(3)
#define RDA_UART_RX_LINE_ERR            BIT(4)
#define RDA_UART_TX_DMA_DONE            BIT(5)
#define RDA_UART_RX_DMA_DONE            BIT(6)
#define RDA_UART_RX_DMA_TIMEOUT         BIT(7)
#define RDA_UART_DTR_RISE               BIT(8)
#define RDA_UART_DTR_FALL               BIT(9)

/* UART_IRQ_CAUSE Bits */
#define RDA_UART_TX_MODEM_STATUS_U      BIT(16)
#define RDA_UART_RX_DATA_AVAILABLE_U    BIT(17)
#define RDA_UART_TX_DATA_NEEDED_U       BIT(18)
#define RDA_UART_RX_TIMEOUT_U           BIT(19)
#define RDA_UART_RX_LINE_ERR_U          BIT(20)
#define RDA_UART_TX_DMA_DONE_U          BIT(21)
#define RDA_UART_RX_DMA_DONE_U          BIT(22)
#define RDA_UART_RX_DMA_TIMEOUT_U       BIT(23)
#define RDA_UART_DTR_RISE_U             BIT(24)
#define RDA_UART_DTR_FALL_U             BIT(25)

/* UART_TRIGGERS Bits */
#define RDA_UART_RX_TRIGGER(x)          (((x) & 0x1f) << 0)
#define RDA_UART_TX_TRIGGER(x)          (((x) & 0xf) << 8)
#define RDA_UART_AFC_LEVEL(x)           (((x) & 0x1f) << 16)

/* UART_CMD_SET Bits */
#define RDA_UART_RI                     BIT(0)
#define RDA_UART_DCD                    BIT(1)
#define RDA_UART_DSR                    BIT(2)
#define RDA_UART_TX_BREAK_CONTROL       BIT(3)
#define RDA_UART_TX_FINISH_N_WAIT       BIT(4)
#define RDA_UART_RTS                    BIT(5)
#define RDA_UART_RX_FIFO_RESET          BIT(6)
#define RDA_UART_TX_FIFO_RESET          BIT(7)

#define RDA_UART_TX_FIFO_SIZE   16

static struct uart_driver rda_uart_driver;

struct rda_uart_port {
        struct uart_port port;
        struct clk *clk;
};

#define to_rda_uart_port(port) container_of(port, struct rda_uart_port, port)

static struct rda_uart_port *rda_uart_ports[RDA_UART_PORT_NUM];

static inline void rda_uart_write(struct uart_port *port, u32 val,
                                  unsigned int off)
{
        writel(val, port->membase + off);
}

static inline u32 rda_uart_read(struct uart_port *port, unsigned int off)
{
        return readl(port->membase + off);
}

static unsigned int rda_uart_tx_empty(struct uart_port *port)
{
        unsigned long flags;
        unsigned int ret;
        u32 val;

        uart_port_lock_irqsave(port, &flags);

        val = rda_uart_read(port, RDA_UART_STATUS);
        ret = (val & RDA_UART_TX_FIFO_MASK) ? TIOCSER_TEMT : 0;

        uart_port_unlock_irqrestore(port, flags);

        return ret;
}

static unsigned int rda_uart_get_mctrl(struct uart_port *port)
{
        unsigned int mctrl = 0;
        u32 cmd_set, status;

        cmd_set = rda_uart_read(port, RDA_UART_CMD_SET);
        status = rda_uart_read(port, RDA_UART_STATUS);
        if (cmd_set & RDA_UART_RTS)
                mctrl |= TIOCM_RTS;
        if (!(status & RDA_UART_CTS))
                mctrl |= TIOCM_CTS;

        return mctrl;
}

static void rda_uart_set_mctrl(struct uart_port *port, unsigned int mctrl)
{
        u32 val;

        if (mctrl & TIOCM_RTS) {
                val = rda_uart_read(port, RDA_UART_CMD_SET);
                rda_uart_write(port, (val | RDA_UART_RTS), RDA_UART_CMD_SET);
        } else {
                /* Clear RTS to stop to receive. */
                val = rda_uart_read(port, RDA_UART_CMD_CLR);
                rda_uart_write(port, (val | RDA_UART_RTS), RDA_UART_CMD_CLR);
        }

        val = rda_uart_read(port, RDA_UART_CTRL);

        if (mctrl & TIOCM_LOOP)
                val |= RDA_UART_LOOP_BACK_EN;
        else
                val &= ~RDA_UART_LOOP_BACK_EN;

        rda_uart_write(port, val, RDA_UART_CTRL);
}

static void rda_uart_stop_tx(struct uart_port *port)
{
        u32 val;

        val = rda_uart_read(port, RDA_UART_IRQ_MASK);
        val &= ~RDA_UART_TX_DATA_NEEDED;
        rda_uart_write(port, val, RDA_UART_IRQ_MASK);

        val = rda_uart_read(port, RDA_UART_CMD_SET);
        val |= RDA_UART_TX_FIFO_RESET;
        rda_uart_write(port, val, RDA_UART_CMD_SET);
}

static void rda_uart_stop_rx(struct uart_port *port)
{
        u32 val;

        val = rda_uart_read(port, RDA_UART_IRQ_MASK);
        val &= ~(RDA_UART_RX_DATA_AVAILABLE | RDA_UART_RX_TIMEOUT);
        rda_uart_write(port, val, RDA_UART_IRQ_MASK);

        /* Read Rx buffer before reset to avoid Rx timeout interrupt */
        val = rda_uart_read(port, RDA_UART_RXTX_BUFFER);

        val = rda_uart_read(port, RDA_UART_CMD_SET);
        val |= RDA_UART_RX_FIFO_RESET;
        rda_uart_write(port, val, RDA_UART_CMD_SET);
}

static void rda_uart_start_tx(struct uart_port *port)
{
        u32 val;

        if (uart_tx_stopped(port)) {
                rda_uart_stop_tx(port);
                return;
        }

        val = rda_uart_read(port, RDA_UART_IRQ_MASK);
        val |= RDA_UART_TX_DATA_NEEDED;
        rda_uart_write(port, val, RDA_UART_IRQ_MASK);
}

static void rda_uart_change_baudrate(struct rda_uart_port *rda_port,
                                     unsigned long baud)
{
        clk_set_rate(rda_port->clk, baud * 8);
}

static void rda_uart_set_termios(struct uart_port *port,
                                 struct ktermios *termios,
                                 const struct ktermios *old)
{
        struct rda_uart_port *rda_port = to_rda_uart_port(port);
        unsigned long flags;
        unsigned int ctrl, cmd_set, cmd_clr, triggers;
        unsigned int baud;
        u32 irq_mask;

        uart_port_lock_irqsave(port, &flags);

        baud = uart_get_baud_rate(port, termios, old, 9600, port->uartclk / 4);
        rda_uart_change_baudrate(rda_port, baud);

        ctrl = rda_uart_read(port, RDA_UART_CTRL);
        cmd_set = rda_uart_read(port, RDA_UART_CMD_SET);
        cmd_clr = rda_uart_read(port, RDA_UART_CMD_CLR);

        switch (termios->c_cflag & CSIZE) {
        case CS5:
        case CS6:
                dev_warn(port->dev, "bit size not supported, using 7 bits\n");
                fallthrough;
        case CS7:
                ctrl &= ~RDA_UART_DBITS_8;
                termios->c_cflag &= ~CSIZE;
                termios->c_cflag |= CS7;
                break;
        default:
                ctrl |= RDA_UART_DBITS_8;
                break;
        }

        /* stop bits */
        if (termios->c_cflag & CSTOPB)
                ctrl |= RDA_UART_TX_SBITS_2;
        else
                ctrl &= ~RDA_UART_TX_SBITS_2;

        /* parity check */
        if (termios->c_cflag & PARENB) {
                ctrl |= RDA_UART_PARITY_EN;

                /* Mark or Space parity */
                if (termios->c_cflag & CMSPAR) {
                        if (termios->c_cflag & PARODD)
                                ctrl |= RDA_UART_PARITY_MARK;
                        else
                                ctrl |= RDA_UART_PARITY_SPACE;
                } else if (termios->c_cflag & PARODD) {
                        ctrl |= RDA_UART_PARITY_ODD;
                } else {
                        ctrl |= RDA_UART_PARITY_EVEN;
                }
        } else {
                ctrl &= ~RDA_UART_PARITY_EN;
        }

        /* Hardware handshake (RTS/CTS) */
        if (termios->c_cflag & CRTSCTS) {
                ctrl   |= RDA_UART_FLOW_CNT_EN;
                cmd_set |= RDA_UART_RTS;
        } else {
                ctrl   &= ~RDA_UART_FLOW_CNT_EN;
                cmd_clr |= RDA_UART_RTS;
        }

        ctrl |= RDA_UART_ENABLE;
        ctrl &= ~RDA_UART_DMA_EN;

        triggers  = (RDA_UART_AFC_LEVEL(20) | RDA_UART_RX_TRIGGER(16));
        irq_mask = rda_uart_read(port, RDA_UART_IRQ_MASK);
        rda_uart_write(port, 0, RDA_UART_IRQ_MASK);

        rda_uart_write(port, triggers, RDA_UART_IRQ_TRIGGERS);
        rda_uart_write(port, ctrl, RDA_UART_CTRL);
        rda_uart_write(port, cmd_set, RDA_UART_CMD_SET);
        rda_uart_write(port, cmd_clr, RDA_UART_CMD_CLR);

        rda_uart_write(port, irq_mask, RDA_UART_IRQ_MASK);

        /* Don't rewrite B0 */
        if (tty_termios_baud_rate(termios))
                tty_termios_encode_baud_rate(termios, baud, baud);

        /* update the per-port timeout */
        uart_update_timeout(port, termios->c_cflag, baud);

        uart_port_unlock_irqrestore(port, flags);
}

static void rda_uart_send_chars(struct uart_port *port)
{
        struct tty_port *tport = &port->state->port;
        unsigned char ch;
        u32 val;

        if (uart_tx_stopped(port))
                return;

        if (port->x_char) {
                while (!(rda_uart_read(port, RDA_UART_STATUS) &
                         RDA_UART_TX_FIFO_MASK))
                        cpu_relax();

                rda_uart_write(port, port->x_char, RDA_UART_RXTX_BUFFER);
                port->icount.tx++;
                port->x_char = 0;
        }

        while ((rda_uart_read(port, RDA_UART_STATUS) & RDA_UART_TX_FIFO_MASK) &&
                        uart_fifo_get(port, &ch))
                rda_uart_write(port, ch, RDA_UART_RXTX_BUFFER);

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

        if (!kfifo_is_empty(&tport->xmit_fifo)) {
                /* Re-enable Tx FIFO interrupt */
                val = rda_uart_read(port, RDA_UART_IRQ_MASK);
                val |= RDA_UART_TX_DATA_NEEDED;
                rda_uart_write(port, val, RDA_UART_IRQ_MASK);
        }
}

static void rda_uart_receive_chars(struct uart_port *port)
{
        u32 status, val;

        status = rda_uart_read(port, RDA_UART_STATUS);
        while ((status & RDA_UART_RX_FIFO_MASK)) {
                char flag = TTY_NORMAL;

                if (status & RDA_UART_RX_PARITY_ERR) {
                        port->icount.parity++;
                        flag = TTY_PARITY;
                }

                if (status & RDA_UART_RX_FRAMING_ERR) {
                        port->icount.frame++;
                        flag = TTY_FRAME;
                }

                if (status & RDA_UART_RX_OVERFLOW_ERR) {
                        port->icount.overrun++;
                        flag = TTY_OVERRUN;
                }

                val = rda_uart_read(port, RDA_UART_RXTX_BUFFER);
                val &= 0xff;

                port->icount.rx++;
                if (!uart_prepare_sysrq_char(port, val))
                        tty_insert_flip_char(&port->state->port, val, flag);

                status = rda_uart_read(port, RDA_UART_STATUS);
        }

        tty_flip_buffer_push(&port->state->port);
}

static irqreturn_t rda_interrupt(int irq, void *dev_id)
{
        struct uart_port *port = dev_id;
        u32 val, irq_mask;

        uart_port_lock(port);

        /* Clear IRQ cause */
        val = rda_uart_read(port, RDA_UART_IRQ_CAUSE);
        rda_uart_write(port, val, RDA_UART_IRQ_CAUSE);

        if (val & (RDA_UART_RX_DATA_AVAILABLE | RDA_UART_RX_TIMEOUT))
                rda_uart_receive_chars(port);

        if (val & (RDA_UART_TX_DATA_NEEDED)) {
                irq_mask = rda_uart_read(port, RDA_UART_IRQ_MASK);
                irq_mask &= ~RDA_UART_TX_DATA_NEEDED;
                rda_uart_write(port, irq_mask, RDA_UART_IRQ_MASK);

                rda_uart_send_chars(port);
        }

        uart_unlock_and_check_sysrq(port);

        return IRQ_HANDLED;
}

static int rda_uart_startup(struct uart_port *port)
{
        unsigned long flags;
        int ret;
        u32 val;

        uart_port_lock_irqsave(port, &flags);
        rda_uart_write(port, 0, RDA_UART_IRQ_MASK);
        uart_port_unlock_irqrestore(port, flags);

        ret = request_irq(port->irq, rda_interrupt, IRQF_NO_SUSPEND,
                          "rda-uart", port);
        if (ret)
                return ret;

        uart_port_lock_irqsave(port, &flags);

        val = rda_uart_read(port, RDA_UART_CTRL);
        val |= RDA_UART_ENABLE;
        rda_uart_write(port, val, RDA_UART_CTRL);

        /* enable rx interrupt */
        val = rda_uart_read(port, RDA_UART_IRQ_MASK);
        val |= (RDA_UART_RX_DATA_AVAILABLE | RDA_UART_RX_TIMEOUT);
        rda_uart_write(port, val, RDA_UART_IRQ_MASK);

        uart_port_unlock_irqrestore(port, flags);

        return 0;
}

static void rda_uart_shutdown(struct uart_port *port)
{
        unsigned long flags;
        u32 val;

        uart_port_lock_irqsave(port, &flags);

        rda_uart_stop_tx(port);
        rda_uart_stop_rx(port);

        val = rda_uart_read(port, RDA_UART_CTRL);
        val &= ~RDA_UART_ENABLE;
        rda_uart_write(port, val, RDA_UART_CTRL);

        uart_port_unlock_irqrestore(port, flags);
}

static const char *rda_uart_type(struct uart_port *port)
{
        return (port->type == PORT_RDA) ? "rda-uart" : NULL;
}

static int rda_uart_request_port(struct uart_port *port)
{
        struct platform_device *pdev = to_platform_device(port->dev);
        struct resource *res;

        res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
        if (!res)
                return -ENXIO;

        if (!devm_request_mem_region(port->dev, port->mapbase,
                                     resource_size(res), dev_name(port->dev)))
                return -EBUSY;

        if (port->flags & UPF_IOREMAP) {
                port->membase = devm_ioremap(port->dev, port->mapbase,
                                                     resource_size(res));
                if (!port->membase)
                        return -EBUSY;
        }

        return 0;
}

static void rda_uart_config_port(struct uart_port *port, int flags)
{
        unsigned long irq_flags;

        if (flags & UART_CONFIG_TYPE) {
                port->type = PORT_RDA;
                rda_uart_request_port(port);
        }

        uart_port_lock_irqsave(port, &irq_flags);

        /* Clear mask, so no surprise interrupts. */
        rda_uart_write(port, 0, RDA_UART_IRQ_MASK);

        /* Clear status register */
        rda_uart_write(port, 0, RDA_UART_STATUS);

        uart_port_unlock_irqrestore(port, irq_flags);
}

static void rda_uart_release_port(struct uart_port *port)
{
        struct platform_device *pdev = to_platform_device(port->dev);
        struct resource *res;

        res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
        if (!res)
                return;

        if (port->flags & UPF_IOREMAP) {
                devm_release_mem_region(port->dev, port->mapbase,
                                        resource_size(res));
                devm_iounmap(port->dev, port->membase);
                port->membase = NULL;
        }
}

static int rda_uart_verify_port(struct uart_port *port,
                                struct serial_struct *ser)
{
        if (port->type != PORT_RDA)
                return -EINVAL;

        if (port->irq != ser->irq)
                return -EINVAL;

        return 0;
}

static const struct uart_ops rda_uart_ops = {
        .tx_empty       = rda_uart_tx_empty,
        .get_mctrl      = rda_uart_get_mctrl,
        .set_mctrl      = rda_uart_set_mctrl,
        .start_tx       = rda_uart_start_tx,
        .stop_tx        = rda_uart_stop_tx,
        .stop_rx        = rda_uart_stop_rx,
        .startup        = rda_uart_startup,
        .shutdown       = rda_uart_shutdown,
        .set_termios    = rda_uart_set_termios,
        .type           = rda_uart_type,
        .request_port   = rda_uart_request_port,
        .release_port   = rda_uart_release_port,
        .config_port    = rda_uart_config_port,
        .verify_port    = rda_uart_verify_port,
};

#ifdef CONFIG_SERIAL_RDA_CONSOLE

static void rda_console_putchar(struct uart_port *port, unsigned char ch)
{
        if (!port->membase)
                return;

        while (!(rda_uart_read(port, RDA_UART_STATUS) & RDA_UART_TX_FIFO_MASK))
                cpu_relax();

        rda_uart_write(port, ch, RDA_UART_RXTX_BUFFER);
}

static void rda_uart_port_write(struct uart_port *port, const char *s,
                                u_int count)
{
        u32 old_irq_mask;
        unsigned long flags;
        int locked = 1;

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

        old_irq_mask = rda_uart_read(port, RDA_UART_IRQ_MASK);
        rda_uart_write(port, 0, RDA_UART_IRQ_MASK);

        uart_console_write(port, s, count, rda_console_putchar);

        /* wait until all contents have been sent out */
        while (!(rda_uart_read(port, RDA_UART_STATUS) & RDA_UART_TX_FIFO_MASK))
                cpu_relax();

        rda_uart_write(port, old_irq_mask, RDA_UART_IRQ_MASK);

        if (locked)
                uart_port_unlock_irqrestore(port, flags);
}

static void rda_uart_console_write(struct console *co, const char *s,
                                   u_int count)
{
        struct rda_uart_port *rda_port;

        rda_port = rda_uart_ports[co->index];
        if (!rda_port)
                return;

        rda_uart_port_write(&rda_port->port, s, count);
}

static int rda_uart_console_setup(struct console *co, char *options)
{
        struct rda_uart_port *rda_port;
        int baud = 921600;
        int bits = 8;
        int parity = 'n';
        int flow = 'n';

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

        rda_port = rda_uart_ports[co->index];
        if (!rda_port || !rda_port->port.membase)
                return -ENODEV;

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

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

static struct console rda_uart_console = {
        .name = RDA_UART_DEV_NAME,
        .write = rda_uart_console_write,
        .device = uart_console_device,
        .setup = rda_uart_console_setup,
        .flags = CON_PRINTBUFFER,
        .index = -1,
        .data = &rda_uart_driver,
};

static int __init rda_uart_console_init(void)
{
        register_console(&rda_uart_console);

        return 0;
}
console_initcall(rda_uart_console_init);

static void rda_uart_early_console_write(struct console *co,
                                         const char *s,
                                         u_int count)
{
        struct earlycon_device *dev = co->data;

        rda_uart_port_write(&dev->port, s, count);
}

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

        device->con->write = rda_uart_early_console_write;

        return 0;
}

OF_EARLYCON_DECLARE(rda, "rda,8810pl-uart",
                    rda_uart_early_console_setup);

#define RDA_UART_CONSOLE (&rda_uart_console)
#else
#define RDA_UART_CONSOLE NULL
#endif /* CONFIG_SERIAL_RDA_CONSOLE */

static struct uart_driver rda_uart_driver = {
        .owner = THIS_MODULE,
        .driver_name = "rda-uart",
        .dev_name = RDA_UART_DEV_NAME,
        .nr = RDA_UART_PORT_NUM,
        .cons = RDA_UART_CONSOLE,
};

static const struct of_device_id rda_uart_dt_matches[] = {
        { .compatible = "rda,8810pl-uart" },
        { }
};
MODULE_DEVICE_TABLE(of, rda_uart_dt_matches);

static int rda_uart_probe(struct platform_device *pdev)
{
        struct resource *res_mem;
        struct rda_uart_port *rda_port;
        int ret, irq;

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

        if (pdev->id < 0 || pdev->id >= RDA_UART_PORT_NUM) {
                dev_err(&pdev->dev, "id %d out of range\n", pdev->id);
                return -EINVAL;
        }

        res_mem = platform_get_resource(pdev, IORESOURCE_MEM, 0);
        if (!res_mem) {
                dev_err(&pdev->dev, "could not get mem\n");
                return -ENODEV;
        }

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

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

        rda_port = devm_kzalloc(&pdev->dev, sizeof(*rda_port), GFP_KERNEL);
        if (!rda_port)
                return -ENOMEM;

        rda_port->clk = devm_clk_get(&pdev->dev, NULL);
        if (IS_ERR(rda_port->clk)) {
                dev_err(&pdev->dev, "could not get clk\n");
                return PTR_ERR(rda_port->clk);
        }

        rda_port->port.dev = &pdev->dev;
        rda_port->port.regshift = 0;
        rda_port->port.line = pdev->id;
        rda_port->port.type = PORT_RDA;
        rda_port->port.iotype = UPIO_MEM;
        rda_port->port.mapbase = res_mem->start;
        rda_port->port.irq = irq;
        rda_port->port.uartclk = clk_get_rate(rda_port->clk);
        if (rda_port->port.uartclk == 0) {
                dev_err(&pdev->dev, "clock rate is zero\n");
                return -EINVAL;
        }
        rda_port->port.flags = UPF_BOOT_AUTOCONF | UPF_IOREMAP |
                               UPF_LOW_LATENCY;
        rda_port->port.x_char = 0;
        rda_port->port.fifosize = RDA_UART_TX_FIFO_SIZE;
        rda_port->port.ops = &rda_uart_ops;

        rda_uart_ports[pdev->id] = rda_port;
        platform_set_drvdata(pdev, rda_port);

        ret = uart_add_one_port(&rda_uart_driver, &rda_port->port);
        if (ret)
                rda_uart_ports[pdev->id] = NULL;

        return ret;
}

static void rda_uart_remove(struct platform_device *pdev)
{
        struct rda_uart_port *rda_port = platform_get_drvdata(pdev);

        uart_remove_one_port(&rda_uart_driver, &rda_port->port);
        rda_uart_ports[pdev->id] = NULL;
}

static struct platform_driver rda_uart_platform_driver = {
        .probe = rda_uart_probe,
        .remove = rda_uart_remove,
        .driver = {
                .name = "rda-uart",
                .of_match_table = rda_uart_dt_matches,
        },
};

static int __init rda_uart_init(void)
{
        int ret;

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

        ret = platform_driver_register(&rda_uart_platform_driver);
        if (ret)
                uart_unregister_driver(&rda_uart_driver);

        return ret;
}

static void __exit rda_uart_exit(void)
{
        platform_driver_unregister(&rda_uart_platform_driver);
        uart_unregister_driver(&rda_uart_driver);
}

module_init(rda_uart_init);
module_exit(rda_uart_exit);

MODULE_AUTHOR("Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>");
MODULE_DESCRIPTION("RDA8810PL serial device driver");
MODULE_LICENSE("GPL");