// SPDX-License-Identifier: GPL-2.0+
/*
 *  Driver for AMBA serial ports
 *
 *  Based on drivers/char/serial.c, by Linus Torvalds, Theodore Ts'o.
 *
 *  Copyright 1999 ARM Limited
 *  Copyright (C) 2000 Deep Blue Solutions Ltd.
 *
 * This is a generic driver for ARM AMBA-type serial ports.  They
 * have a lot of 16550-like features, but are not register compatible.
 * Note that although they do have CTS, DCD and DSR inputs, they do
 * not have an RI input, nor do they have DTR or RTS outputs.  If
 * required, these have to be supplied via some other means (eg, GPIO)
 * and hooked into this driver.
 */

#include <linux/module.h>
#include <linux/ioport.h>
#include <linux/init.h>
#include <linux/console.h>
#include <linux/sysrq.h>
#include <linux/device.h>
#include <linux/tty.h>
#include <linux/tty_flip.h>
#include <linux/serial_core.h>
#include <linux/serial.h>
#include <linux/amba/bus.h>
#include <linux/amba/serial.h>
#include <linux/clk.h>
#include <linux/slab.h>
#include <linux/io.h>

#define UART_NR         8

#define SERIAL_AMBA_MAJOR       204
#define SERIAL_AMBA_MINOR       16
#define SERIAL_AMBA_NR          UART_NR

#define AMBA_ISR_PASS_LIMIT     256

#define UART_RX_DATA(s)         (((s) & UART01x_FR_RXFE) == 0)
#define UART_TX_READY(s)        (((s) & UART01x_FR_TXFF) == 0)

#define UART_DUMMY_RSR_RX       256
#define UART_PORT_SIZE          64

/*
 * We wrap our port structure around the generic uart_port.
 */
struct uart_amba_port {
        struct uart_port        port;
        struct clk              *clk;
        struct amba_device      *dev;
        struct amba_pl010_data  *data;
        unsigned int            old_status;
};

static void pl010_stop_tx(struct uart_port *port)
{
        struct uart_amba_port *uap =
                container_of(port, struct uart_amba_port, port);
        unsigned int cr;

        cr = readb(uap->port.membase + UART010_CR);
        cr &= ~UART010_CR_TIE;
        writel(cr, uap->port.membase + UART010_CR);
}

static void pl010_start_tx(struct uart_port *port)
{
        struct uart_amba_port *uap =
                container_of(port, struct uart_amba_port, port);
        unsigned int cr;

        cr = readb(uap->port.membase + UART010_CR);
        cr |= UART010_CR_TIE;
        writel(cr, uap->port.membase + UART010_CR);
}

static void pl010_stop_rx(struct uart_port *port)
{
        struct uart_amba_port *uap =
                container_of(port, struct uart_amba_port, port);
        unsigned int cr;

        cr = readb(uap->port.membase + UART010_CR);
        cr &= ~(UART010_CR_RIE | UART010_CR_RTIE);
        writel(cr, uap->port.membase + UART010_CR);
}

static void pl010_disable_ms(struct uart_port *port)
{
        struct uart_amba_port *uap = (struct uart_amba_port *)port;
        unsigned int cr;

        cr = readb(uap->port.membase + UART010_CR);
        cr &= ~UART010_CR_MSIE;
        writel(cr, uap->port.membase + UART010_CR);
}

static void pl010_enable_ms(struct uart_port *port)
{
        struct uart_amba_port *uap =
                container_of(port, struct uart_amba_port, port);
        unsigned int cr;

        cr = readb(uap->port.membase + UART010_CR);
        cr |= UART010_CR_MSIE;
        writel(cr, uap->port.membase + UART010_CR);
}

static void pl010_rx_chars(struct uart_port *port)
{
        unsigned int status, rsr, max_count = 256;
        u8 ch, flag;

        status = readb(port->membase + UART01x_FR);
        while (UART_RX_DATA(status) && max_count--) {
                ch = readb(port->membase + UART01x_DR);
                flag = TTY_NORMAL;

                port->icount.rx++;

                /*
                 * Note that the error handling code is
                 * out of the main execution path
                 */
                rsr = readb(port->membase + UART01x_RSR) | UART_DUMMY_RSR_RX;
                if (unlikely(rsr & UART01x_RSR_ANY)) {
                        writel(0, port->membase + UART01x_ECR);

                        if (rsr & UART01x_RSR_BE) {
                                rsr &= ~(UART01x_RSR_FE | UART01x_RSR_PE);
                                port->icount.brk++;
                                if (uart_handle_break(port))
                                        goto ignore_char;
                        } else if (rsr & UART01x_RSR_PE)
                                port->icount.parity++;
                        else if (rsr & UART01x_RSR_FE)
                                port->icount.frame++;
                        if (rsr & UART01x_RSR_OE)
                                port->icount.overrun++;

                        rsr &= port->read_status_mask;

                        if (rsr & UART01x_RSR_BE)
                                flag = TTY_BREAK;
                        else if (rsr & UART01x_RSR_PE)
                                flag = TTY_PARITY;
                        else if (rsr & UART01x_RSR_FE)
                                flag = TTY_FRAME;
                }

                if (uart_handle_sysrq_char(port, ch))
                        goto ignore_char;

                uart_insert_char(port, rsr, UART01x_RSR_OE, ch, flag);

        ignore_char:
                status = readb(port->membase + UART01x_FR);
        }
        tty_flip_buffer_push(&port->state->port);
}

static void pl010_tx_chars(struct uart_port *port)
{
        u8 ch;

        uart_port_tx_limited(port, ch, port->fifosize >> 1,
                true,
                writel(ch, port->membase + UART01x_DR),
                ({}));
}

static void pl010_modem_status(struct uart_amba_port *uap)
{
        struct uart_port *port = &uap->port;
        unsigned int status, delta;

        writel(0, port->membase + UART010_ICR);

        status = readb(port->membase + UART01x_FR) & UART01x_FR_MODEM_ANY;

        delta = status ^ uap->old_status;
        uap->old_status = status;

        if (!delta)
                return;

        if (delta & UART01x_FR_DCD)
                uart_handle_dcd_change(port, status & UART01x_FR_DCD);

        if (delta & UART01x_FR_DSR)
                port->icount.dsr++;

        if (delta & UART01x_FR_CTS)
                uart_handle_cts_change(port, status & UART01x_FR_CTS);

        wake_up_interruptible(&port->state->port.delta_msr_wait);
}

static irqreturn_t pl010_int(int irq, void *dev_id)
{
        struct uart_amba_port *uap = dev_id;
        struct uart_port *port = &uap->port;
        unsigned int status, pass_counter = AMBA_ISR_PASS_LIMIT;
        int handled = 0;

        uart_port_lock(port);

        status = readb(port->membase + UART010_IIR);
        if (status) {
                do {
                        if (status & (UART010_IIR_RTIS | UART010_IIR_RIS))
                                pl010_rx_chars(port);
                        if (status & UART010_IIR_MIS)
                                pl010_modem_status(uap);
                        if (status & UART010_IIR_TIS)
                                pl010_tx_chars(port);

                        if (pass_counter-- == 0)
                                break;

                        status = readb(port->membase + UART010_IIR);
                } while (status & (UART010_IIR_RTIS | UART010_IIR_RIS |
                                   UART010_IIR_TIS));
                handled = 1;
        }

        uart_port_unlock(port);

        return IRQ_RETVAL(handled);
}

static unsigned int pl010_tx_empty(struct uart_port *port)
{
        unsigned int status = readb(port->membase + UART01x_FR);

        return status & UART01x_FR_BUSY ? 0 : TIOCSER_TEMT;
}

static unsigned int pl010_get_mctrl(struct uart_port *port)
{
        unsigned int result = 0;
        unsigned int status;

        status = readb(port->membase + UART01x_FR);
        if (status & UART01x_FR_DCD)
                result |= TIOCM_CAR;
        if (status & UART01x_FR_DSR)
                result |= TIOCM_DSR;
        if (status & UART01x_FR_CTS)
                result |= TIOCM_CTS;

        return result;
}

static void pl010_set_mctrl(struct uart_port *port, unsigned int mctrl)
{
        struct uart_amba_port *uap =
                container_of(port, struct uart_amba_port, port);

        if (uap->data)
                uap->data->set_mctrl(uap->dev, port->membase, mctrl);
}

static void pl010_break_ctl(struct uart_port *port, int break_state)
{
        unsigned long flags;
        unsigned int lcr_h;

        uart_port_lock_irqsave(port, &flags);
        lcr_h = readb(port->membase + UART010_LCRH);
        if (break_state == -1)
                lcr_h |= UART01x_LCRH_BRK;
        else
                lcr_h &= ~UART01x_LCRH_BRK;
        writel(lcr_h, port->membase + UART010_LCRH);
        uart_port_unlock_irqrestore(port, flags);
}

static int pl010_startup(struct uart_port *port)
{
        struct uart_amba_port *uap =
                container_of(port, struct uart_amba_port, port);
        int retval;

        /*
         * Try to enable the clock producer.
         */
        retval = clk_prepare_enable(uap->clk);
        if (retval)
                goto out;

        port->uartclk = clk_get_rate(uap->clk);

        /*
         * Allocate the IRQ
         */
        retval = request_irq(port->irq, pl010_int, 0, "uart-pl010", uap);
        if (retval)
                goto clk_dis;

        /*
         * initialise the old status of the modem signals
         */
        uap->old_status = readb(port->membase + UART01x_FR) & UART01x_FR_MODEM_ANY;

        /*
         * Finally, enable interrupts
         */
        writel(UART01x_CR_UARTEN | UART010_CR_RIE | UART010_CR_RTIE,
               port->membase + UART010_CR);

        return 0;

 clk_dis:
        clk_disable_unprepare(uap->clk);
 out:
        return retval;
}

static void pl010_shutdown(struct uart_port *port)
{
        struct uart_amba_port *uap =
                container_of(port, struct uart_amba_port, port);

        /*
         * Free the interrupt
         */
        free_irq(port->irq, uap);

        /*
         * disable all interrupts, disable the port
         */
        writel(0, port->membase + UART010_CR);

        /* disable break condition and fifos */
        writel(readb(port->membase + UART010_LCRH) &
                ~(UART01x_LCRH_BRK | UART01x_LCRH_FEN),
               port->membase + UART010_LCRH);

        /*
         * Shut down the clock producer
         */
        clk_disable_unprepare(uap->clk);
}

static void
pl010_set_termios(struct uart_port *port, struct ktermios *termios,
                  const struct ktermios *old)
{
        unsigned int lcr_h, old_cr;
        unsigned long flags;
        unsigned int baud, quot;

        /*
         * Ask the core to calculate the divisor for us.
         */
        baud = uart_get_baud_rate(port, termios, old, 0, port->uartclk / 16);
        quot = uart_get_divisor(port, baud);

        switch (termios->c_cflag & CSIZE) {
        case CS5:
                lcr_h = UART01x_LCRH_WLEN_5;
                break;
        case CS6:
                lcr_h = UART01x_LCRH_WLEN_6;
                break;
        case CS7:
                lcr_h = UART01x_LCRH_WLEN_7;
                break;
        default: // CS8
                lcr_h = UART01x_LCRH_WLEN_8;
                break;
        }
        if (termios->c_cflag & CSTOPB)
                lcr_h |= UART01x_LCRH_STP2;
        if (termios->c_cflag & PARENB) {
                lcr_h |= UART01x_LCRH_PEN;
                if (!(termios->c_cflag & PARODD))
                        lcr_h |= UART01x_LCRH_EPS;
        }
        if (port->fifosize > 1)
                lcr_h |= UART01x_LCRH_FEN;

        uart_port_lock_irqsave(port, &flags);

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

        port->read_status_mask = UART01x_RSR_OE;
        if (termios->c_iflag & INPCK)
                port->read_status_mask |= UART01x_RSR_FE | UART01x_RSR_PE;
        if (termios->c_iflag & (IGNBRK | BRKINT | PARMRK))
                port->read_status_mask |= UART01x_RSR_BE;

        /*
         * Characters to ignore
         */
        port->ignore_status_mask = 0;
        if (termios->c_iflag & IGNPAR)
                port->ignore_status_mask |= UART01x_RSR_FE | UART01x_RSR_PE;
        if (termios->c_iflag & IGNBRK) {
                port->ignore_status_mask |= UART01x_RSR_BE;
                /*
                 * If we're ignoring parity and break indicators,
                 * ignore overruns too (for real raw support).
                 */
                if (termios->c_iflag & IGNPAR)
                        port->ignore_status_mask |= UART01x_RSR_OE;
        }

        /*
         * Ignore all characters if CREAD is not set.
         */
        if ((termios->c_cflag & CREAD) == 0)
                port->ignore_status_mask |= UART_DUMMY_RSR_RX;

        old_cr = readb(port->membase + UART010_CR) & ~UART010_CR_MSIE;

        if (UART_ENABLE_MS(port, termios->c_cflag))
                old_cr |= UART010_CR_MSIE;

        /* Set baud rate */
        quot -= 1;
        writel((quot & 0xf00) >> 8, port->membase + UART010_LCRM);
        writel(quot & 0xff, port->membase + UART010_LCRL);

        /*
         * ----------v----------v----------v----------v-----
         * NOTE: MUST BE WRITTEN AFTER UARTLCR_M & UARTLCR_L
         * ----------^----------^----------^----------^-----
         */
        writel(lcr_h, port->membase + UART010_LCRH);
        writel(old_cr, port->membase + UART010_CR);

        uart_port_unlock_irqrestore(port, flags);
}

static void pl010_set_ldisc(struct uart_port *port, struct ktermios *termios)
{
        if (termios->c_line == N_PPS) {
                port->flags |= UPF_HARDPPS_CD;
                uart_port_lock_irq(port);
                pl010_enable_ms(port);
                uart_port_unlock_irq(port);
        } else {
                port->flags &= ~UPF_HARDPPS_CD;
                if (!UART_ENABLE_MS(port, termios->c_cflag)) {
                        uart_port_lock_irq(port);
                        pl010_disable_ms(port);
                        uart_port_unlock_irq(port);
                }
        }
}

static const char *pl010_type(struct uart_port *port)
{
        return port->type == PORT_AMBA ? "AMBA" : NULL;
}

/*
 * Release the memory region(s) being used by 'port'
 */
static void pl010_release_port(struct uart_port *port)
{
        release_mem_region(port->mapbase, UART_PORT_SIZE);
}

/*
 * Request the memory region(s) being used by 'port'
 */
static int pl010_request_port(struct uart_port *port)
{
        return request_mem_region(port->mapbase, UART_PORT_SIZE, "uart-pl010")
                        != NULL ? 0 : -EBUSY;
}

/*
 * Configure/autoconfigure the port.
 */
static void pl010_config_port(struct uart_port *port, int flags)
{
        if (flags & UART_CONFIG_TYPE) {
                port->type = PORT_AMBA;
                pl010_request_port(port);
        }
}

/*
 * verify the new serial_struct (for TIOCSSERIAL).
 */
static int pl010_verify_port(struct uart_port *port, struct serial_struct *ser)
{
        int ret = 0;
        if (ser->type != PORT_UNKNOWN && ser->type != PORT_AMBA)
                ret = -EINVAL;
        if (ser->irq < 0 || ser->irq >= irq_get_nr_irqs())
                ret = -EINVAL;
        if (ser->baud_base < 9600)
                ret = -EINVAL;
        return ret;
}

static const struct uart_ops amba_pl010_pops = {
        .tx_empty       = pl010_tx_empty,
        .set_mctrl      = pl010_set_mctrl,
        .get_mctrl      = pl010_get_mctrl,
        .stop_tx        = pl010_stop_tx,
        .start_tx       = pl010_start_tx,
        .stop_rx        = pl010_stop_rx,
        .enable_ms      = pl010_enable_ms,
        .break_ctl      = pl010_break_ctl,
        .startup        = pl010_startup,
        .shutdown       = pl010_shutdown,
        .set_termios    = pl010_set_termios,
        .set_ldisc      = pl010_set_ldisc,
        .type           = pl010_type,
        .release_port   = pl010_release_port,
        .request_port   = pl010_request_port,
        .config_port    = pl010_config_port,
        .verify_port    = pl010_verify_port,
};

static struct uart_amba_port *amba_ports[UART_NR];

#ifdef CONFIG_SERIAL_AMBA_PL010_CONSOLE

static void pl010_console_putchar(struct uart_port *port, unsigned char ch)
{
        unsigned int status;

        do {
                status = readb(port->membase + UART01x_FR);
                barrier();
        } while (!UART_TX_READY(status));
        writel(ch, port->membase + UART01x_DR);
}

static void
pl010_console_write(struct console *co, const char *s, unsigned int count)
{
        struct uart_amba_port *uap = amba_ports[co->index];
        struct uart_port *port = &uap->port;
        unsigned int status, old_cr;

        clk_enable(uap->clk);

        /*
         *      First save the CR then disable the interrupts
         */
        old_cr = readb(port->membase + UART010_CR);
        writel(UART01x_CR_UARTEN, port->membase + UART010_CR);

        uart_console_write(port, s, count, pl010_console_putchar);

        /*
         *      Finally, wait for transmitter to become empty
         *      and restore the TCR
         */
        do {
                status = readb(port->membase + UART01x_FR);
                barrier();
        } while (status & UART01x_FR_BUSY);
        writel(old_cr, port->membase + UART010_CR);

        clk_disable(uap->clk);
}

static void __init
pl010_console_get_options(struct uart_amba_port *uap, int *baud,
                             int *parity, int *bits)
{
        if (readb(uap->port.membase + UART010_CR) & UART01x_CR_UARTEN) {
                unsigned int lcr_h, quot;
                lcr_h = readb(uap->port.membase + UART010_LCRH);

                *parity = 'n';
                if (lcr_h & UART01x_LCRH_PEN) {
                        if (lcr_h & UART01x_LCRH_EPS)
                                *parity = 'e';
                        else
                                *parity = 'o';
                }

                if ((lcr_h & 0x60) == UART01x_LCRH_WLEN_7)
                        *bits = 7;
                else
                        *bits = 8;

                quot = readb(uap->port.membase + UART010_LCRL) |
                       readb(uap->port.membase + UART010_LCRM) << 8;
                *baud = uap->port.uartclk / (16 * (quot + 1));
        }
}

static int __init pl010_console_setup(struct console *co, char *options)
{
        struct uart_amba_port *uap;
        int baud = 38400;
        int bits = 8;
        int parity = 'n';
        int flow = 'n';
        int ret;

        /*
         * Check whether an invalid uart number has been specified, and
         * if so, search for the first available port that does have
         * console support.
         */
        if (co->index >= UART_NR)
                co->index = 0;
        uap = amba_ports[co->index];
        if (!uap)
                return -ENODEV;

        ret = clk_prepare(uap->clk);
        if (ret)
                return ret;

        uap->port.uartclk = clk_get_rate(uap->clk);

        if (options)
                uart_parse_options(options, &baud, &parity, &bits, &flow);
        else
                pl010_console_get_options(uap, &baud, &parity, &bits);

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

static struct uart_driver amba_reg;
static struct console amba_console = {
        .name           = "ttyAM",
        .write          = pl010_console_write,
        .device         = uart_console_device,
        .setup          = pl010_console_setup,
        .flags          = CON_PRINTBUFFER,
        .index          = -1,
        .data           = &amba_reg,
};

#define AMBA_CONSOLE    &amba_console
#else
#define AMBA_CONSOLE    NULL
#endif

static DEFINE_MUTEX(amba_reg_lock);
static struct uart_driver amba_reg = {
        .owner                  = THIS_MODULE,
        .driver_name            = "ttyAM",
        .dev_name               = "ttyAM",
        .major                  = SERIAL_AMBA_MAJOR,
        .minor                  = SERIAL_AMBA_MINOR,
        .nr                     = UART_NR,
        .cons                   = AMBA_CONSOLE,
};

static int pl010_probe(struct amba_device *dev, const struct amba_id *id)
{
        struct uart_amba_port *uap;
        void __iomem *base;
        int i, ret;

        for (i = 0; i < ARRAY_SIZE(amba_ports); i++)
                if (amba_ports[i] == NULL)
                        break;

        if (i == ARRAY_SIZE(amba_ports))
                return -EBUSY;

        uap = devm_kzalloc(&dev->dev, sizeof(struct uart_amba_port),
                           GFP_KERNEL);
        if (!uap)
                return -ENOMEM;

        base = devm_ioremap(&dev->dev, dev->res.start,
                            resource_size(&dev->res));
        if (!base)
                return -ENOMEM;

        uap->clk = devm_clk_get(&dev->dev, NULL);
        if (IS_ERR(uap->clk))
                return PTR_ERR(uap->clk);

        uap->port.dev = &dev->dev;
        uap->port.mapbase = dev->res.start;
        uap->port.membase = base;
        uap->port.iotype = UPIO_MEM;
        uap->port.irq = dev->irq[0];
        uap->port.fifosize = 16;
        uap->port.has_sysrq = IS_ENABLED(CONFIG_SERIAL_AMBA_PL010_CONSOLE);
        uap->port.ops = &amba_pl010_pops;
        uap->port.flags = UPF_BOOT_AUTOCONF;
        uap->port.line = i;
        uap->dev = dev;
        uap->data = dev_get_platdata(&dev->dev);

        amba_ports[i] = uap;

        amba_set_drvdata(dev, uap);

        mutex_lock(&amba_reg_lock);
        if (!amba_reg.state) {
                ret = uart_register_driver(&amba_reg);
                if (ret < 0) {
                        mutex_unlock(&amba_reg_lock);
                        dev_err(uap->port.dev,
                                "Failed to register AMBA-PL010 driver\n");
                        return ret;
                }
        }
        mutex_unlock(&amba_reg_lock);

        ret = uart_add_one_port(&amba_reg, &uap->port);
        if (ret)
                amba_ports[i] = NULL;

        return ret;
}

static void pl010_remove(struct amba_device *dev)
{
        struct uart_amba_port *uap = amba_get_drvdata(dev);
        int i;
        bool busy = false;

        uart_remove_one_port(&amba_reg, &uap->port);

        for (i = 0; i < ARRAY_SIZE(amba_ports); i++)
                if (amba_ports[i] == uap)
                        amba_ports[i] = NULL;
                else if (amba_ports[i])
                        busy = true;

        if (!busy)
                uart_unregister_driver(&amba_reg);
}

#ifdef CONFIG_PM_SLEEP
static int pl010_suspend(struct device *dev)
{
        struct uart_amba_port *uap = dev_get_drvdata(dev);

        if (uap)
                uart_suspend_port(&amba_reg, &uap->port);

        return 0;
}

static int pl010_resume(struct device *dev)
{
        struct uart_amba_port *uap = dev_get_drvdata(dev);

        if (uap)
                uart_resume_port(&amba_reg, &uap->port);

        return 0;
}
#endif

static SIMPLE_DEV_PM_OPS(pl010_dev_pm_ops, pl010_suspend, pl010_resume);

static const struct amba_id pl010_ids[] = {
        {
                .id     = 0x00041010,
                .mask   = 0x000fffff,
        },
        { 0, 0 },
};

MODULE_DEVICE_TABLE(amba, pl010_ids);

static struct amba_driver pl010_driver = {
        .drv = {
                .name   = "uart-pl010",
                .pm     = &pl010_dev_pm_ops,
        },
        .id_table       = pl010_ids,
        .probe          = pl010_probe,
        .remove         = pl010_remove,
};

static int __init pl010_init(void)
{
        printk(KERN_INFO "Serial: AMBA driver\n");

        return  amba_driver_register(&pl010_driver);
}

static void __exit pl010_exit(void)
{
        amba_driver_unregister(&pl010_driver);
}

module_init(pl010_init);
module_exit(pl010_exit);

MODULE_AUTHOR("ARM Ltd/Deep Blue Solutions Ltd");
MODULE_DESCRIPTION("ARM AMBA serial port driver");
MODULE_LICENSE("GPL");