// SPDX-License-Identifier: GPL-2.0+
/*
 * altera_uart.c -- Altera UART driver
 *
 * Based on mcf.c -- Freescale ColdFire UART driver
 *
 * (C) Copyright 2003-2007, Greg Ungerer <gerg@snapgear.com>
 * (C) Copyright 2008, Thomas Chou <thomas@wytron.com.tw>
 * (C) Copyright 2010, Tobias Klauser <tklauser@distanz.ch>
 */

#include <linux/kernel.h>
#include <linux/init.h>
#include <linux/timer.h>
#include <linux/interrupt.h>
#include <linux/module.h>
#include <linux/console.h>
#include <linux/tty.h>
#include <linux/tty_flip.h>
#include <linux/serial.h>
#include <linux/serial_core.h>
#include <linux/platform_device.h>
#include <linux/of.h>
#include <linux/io.h>
#include <linux/altera_uart.h>

#define SERIAL_ALTERA_MAJOR 204
#define SERIAL_ALTERA_MINOR 213

/*
 * Altera UART register definitions according to the Nios UART datasheet:
 * http://www.altera.com/literature/ds/ds_nios_uart.pdf
 */

#define ALTERA_UART_SIZE                32

#define ALTERA_UART_RXDATA_REG          0
#define ALTERA_UART_TXDATA_REG          4
#define ALTERA_UART_STATUS_REG          8
#define ALTERA_UART_CONTROL_REG         12
#define ALTERA_UART_DIVISOR_REG         16
#define ALTERA_UART_EOP_REG             20

#define ALTERA_UART_STATUS_PE_MSK       0x0001  /* parity error */
#define ALTERA_UART_STATUS_FE_MSK       0x0002  /* framing error */
#define ALTERA_UART_STATUS_BRK_MSK      0x0004  /* break */
#define ALTERA_UART_STATUS_ROE_MSK      0x0008  /* RX overrun error */
#define ALTERA_UART_STATUS_TOE_MSK      0x0010  /* TX overrun error */
#define ALTERA_UART_STATUS_TMT_MSK      0x0020  /* TX shift register state */
#define ALTERA_UART_STATUS_TRDY_MSK     0x0040  /* TX ready */
#define ALTERA_UART_STATUS_RRDY_MSK     0x0080  /* RX ready */
#define ALTERA_UART_STATUS_E_MSK        0x0100  /* exception condition */
#define ALTERA_UART_STATUS_DCTS_MSK     0x0400  /* CTS logic-level change */
#define ALTERA_UART_STATUS_CTS_MSK      0x0800  /* CTS logic state */
#define ALTERA_UART_STATUS_EOP_MSK      0x1000  /* EOP written/read */

                                                /* Enable interrupt on... */
#define ALTERA_UART_CONTROL_PE_MSK      0x0001  /* ...parity error */
#define ALTERA_UART_CONTROL_FE_MSK      0x0002  /* ...framing error */
#define ALTERA_UART_CONTROL_BRK_MSK     0x0004  /* ...break */
#define ALTERA_UART_CONTROL_ROE_MSK     0x0008  /* ...RX overrun */
#define ALTERA_UART_CONTROL_TOE_MSK     0x0010  /* ...TX overrun */
#define ALTERA_UART_CONTROL_TMT_MSK     0x0020  /* ...TX shift register empty */
#define ALTERA_UART_CONTROL_TRDY_MSK    0x0040  /* ...TX ready */
#define ALTERA_UART_CONTROL_RRDY_MSK    0x0080  /* ...RX ready */
#define ALTERA_UART_CONTROL_E_MSK       0x0100  /* ...exception*/

#define ALTERA_UART_CONTROL_TRBK_MSK    0x0200  /* TX break */
#define ALTERA_UART_CONTROL_DCTS_MSK    0x0400  /* Interrupt on CTS change */
#define ALTERA_UART_CONTROL_RTS_MSK     0x0800  /* RTS signal */
#define ALTERA_UART_CONTROL_EOP_MSK     0x1000  /* Interrupt on EOP */

/*
 * Local per-uart structure.
 */
struct altera_uart {
        struct uart_port port;
        struct timer_list tmr;
        unsigned int sigs;      /* Local copy of line sigs */
        unsigned short imr;     /* Local IMR mirror */
};

static u32 altera_uart_readl(struct uart_port *port, int reg)
{
        return readl(port->membase + (reg << port->regshift));
}

static void altera_uart_writel(struct uart_port *port, u32 dat, int reg)
{
        writel(dat, port->membase + (reg << port->regshift));
}

static unsigned int altera_uart_tx_empty(struct uart_port *port)
{
        return (altera_uart_readl(port, ALTERA_UART_STATUS_REG) &
                ALTERA_UART_STATUS_TMT_MSK) ? TIOCSER_TEMT : 0;
}

static unsigned int altera_uart_get_mctrl(struct uart_port *port)
{
        struct altera_uart *pp = container_of(port, struct altera_uart, port);
        unsigned int sigs;

        sigs = (altera_uart_readl(port, ALTERA_UART_STATUS_REG) &
             ALTERA_UART_STATUS_CTS_MSK) ? TIOCM_CTS : 0;
        sigs |= (pp->sigs & TIOCM_RTS);

        return sigs;
}

static void altera_uart_update_ctrl_reg(struct altera_uart *pp)
{
        unsigned short imr = pp->imr;

        /*
         * If the device doesn't have an irq, ensure that the irq bits are
         * masked out to keep the irq line inactive.
         */
        if (!pp->port.irq)
                imr &= ALTERA_UART_CONTROL_TRBK_MSK | ALTERA_UART_CONTROL_RTS_MSK;

        altera_uart_writel(&pp->port, imr, ALTERA_UART_CONTROL_REG);
}

static void altera_uart_set_mctrl(struct uart_port *port, unsigned int sigs)
{
        struct altera_uart *pp = container_of(port, struct altera_uart, port);

        pp->sigs = sigs;
        if (sigs & TIOCM_RTS)
                pp->imr |= ALTERA_UART_CONTROL_RTS_MSK;
        else
                pp->imr &= ~ALTERA_UART_CONTROL_RTS_MSK;
        altera_uart_update_ctrl_reg(pp);
}

static void altera_uart_start_tx(struct uart_port *port)
{
        struct altera_uart *pp = container_of(port, struct altera_uart, port);

        pp->imr |= ALTERA_UART_CONTROL_TRDY_MSK;
        altera_uart_update_ctrl_reg(pp);
}

static void altera_uart_stop_tx(struct uart_port *port)
{
        struct altera_uart *pp = container_of(port, struct altera_uart, port);

        pp->imr &= ~ALTERA_UART_CONTROL_TRDY_MSK;
        altera_uart_update_ctrl_reg(pp);
}

static void altera_uart_stop_rx(struct uart_port *port)
{
        struct altera_uart *pp = container_of(port, struct altera_uart, port);

        pp->imr &= ~ALTERA_UART_CONTROL_RRDY_MSK;
        altera_uart_update_ctrl_reg(pp);
}

static void altera_uart_break_ctl(struct uart_port *port, int break_state)
{
        struct altera_uart *pp = container_of(port, struct altera_uart, port);
        unsigned long flags;

        uart_port_lock_irqsave(port, &flags);
        if (break_state == -1)
                pp->imr |= ALTERA_UART_CONTROL_TRBK_MSK;
        else
                pp->imr &= ~ALTERA_UART_CONTROL_TRBK_MSK;
        altera_uart_update_ctrl_reg(pp);
        uart_port_unlock_irqrestore(port, flags);
}

static void altera_uart_set_termios(struct uart_port *port,
                                    struct ktermios *termios,
                                    const struct ktermios *old)
{
        unsigned long flags;
        unsigned int baud, baudclk;

        baud = uart_get_baud_rate(port, termios, old, 0, 4000000);
        baudclk = port->uartclk / baud;

        if (old)
                tty_termios_copy_hw(termios, old);
        tty_termios_encode_baud_rate(termios, baud, baud);

        uart_port_lock_irqsave(port, &flags);
        uart_update_timeout(port, termios->c_cflag, baud);
        altera_uart_writel(port, baudclk, ALTERA_UART_DIVISOR_REG);
        uart_port_unlock_irqrestore(port, flags);

        /*
         * FIXME: port->read_status_mask and port->ignore_status_mask
         * need to be initialized based on termios settings for
         * INPCK, IGNBRK, IGNPAR, PARMRK, BRKINT
         */
}

static void altera_uart_rx_chars(struct uart_port *port)
{
        unsigned short status;
        u8 ch, flag;

        while ((status = altera_uart_readl(port, ALTERA_UART_STATUS_REG)) &
               ALTERA_UART_STATUS_RRDY_MSK) {
                ch = altera_uart_readl(port, ALTERA_UART_RXDATA_REG);
                flag = TTY_NORMAL;
                port->icount.rx++;

                if (status & ALTERA_UART_STATUS_E_MSK) {
                        altera_uart_writel(port, status,
                                           ALTERA_UART_STATUS_REG);

                        if (status & ALTERA_UART_STATUS_BRK_MSK) {
                                port->icount.brk++;
                                if (uart_handle_break(port))
                                        continue;
                        } else if (status & ALTERA_UART_STATUS_PE_MSK) {
                                port->icount.parity++;
                        } else if (status & ALTERA_UART_STATUS_ROE_MSK) {
                                port->icount.overrun++;
                        } else if (status & ALTERA_UART_STATUS_FE_MSK) {
                                port->icount.frame++;
                        }

                        status &= port->read_status_mask;

                        if (status & ALTERA_UART_STATUS_BRK_MSK)
                                flag = TTY_BREAK;
                        else if (status & ALTERA_UART_STATUS_PE_MSK)
                                flag = TTY_PARITY;
                        else if (status & ALTERA_UART_STATUS_FE_MSK)
                                flag = TTY_FRAME;
                }

                if (uart_handle_sysrq_char(port, ch))
                        continue;
                uart_insert_char(port, status, ALTERA_UART_STATUS_ROE_MSK, ch,
                                 flag);
        }

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

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

        uart_port_tx(port, ch,
                altera_uart_readl(port, ALTERA_UART_STATUS_REG) &
                                ALTERA_UART_STATUS_TRDY_MSK,
                altera_uart_writel(port, ch, ALTERA_UART_TXDATA_REG));
}

static irqreturn_t altera_uart_interrupt(int irq, void *data)
{
        struct uart_port *port = data;
        struct altera_uart *pp = container_of(port, struct altera_uart, port);
        unsigned long flags;
        unsigned int isr;

        isr = altera_uart_readl(port, ALTERA_UART_STATUS_REG) & pp->imr;

        uart_port_lock_irqsave(port, &flags);
        if (isr & ALTERA_UART_STATUS_RRDY_MSK)
                altera_uart_rx_chars(port);
        if (isr & ALTERA_UART_STATUS_TRDY_MSK)
                altera_uart_tx_chars(port);
        uart_port_unlock_irqrestore(port, flags);

        return IRQ_RETVAL(isr);
}

static void altera_uart_timer(struct timer_list *t)
{
        struct altera_uart *pp = timer_container_of(pp, t, tmr);
        struct uart_port *port = &pp->port;

        altera_uart_interrupt(0, port);
        mod_timer(&pp->tmr, jiffies + uart_poll_timeout(port));
}

static void altera_uart_config_port(struct uart_port *port, int flags)
{
        port->type = PORT_ALTERA_UART;

        /* Clear mask, so no surprise interrupts. */
        altera_uart_writel(port, 0, ALTERA_UART_CONTROL_REG);
        /* Clear status register */
        altera_uart_writel(port, 0, ALTERA_UART_STATUS_REG);
}

static int altera_uart_startup(struct uart_port *port)
{
        struct altera_uart *pp = container_of(port, struct altera_uart, port);
        unsigned long flags;

        if (!port->irq) {
                timer_setup(&pp->tmr, altera_uart_timer, 0);
                mod_timer(&pp->tmr, jiffies + uart_poll_timeout(port));
        } else {
                int ret;

                ret = request_irq(port->irq, altera_uart_interrupt, 0,
                                dev_name(port->dev), port);
                if (ret) {
                        dev_err(port->dev, "unable to attach Altera UART %d interrupt vector=%d\n",
                                port->line, port->irq);
                        return ret;
                }
        }

        uart_port_lock_irqsave(port, &flags);

        /* Enable RX interrupts now */
        pp->imr = ALTERA_UART_CONTROL_RRDY_MSK;
        altera_uart_update_ctrl_reg(pp);

        uart_port_unlock_irqrestore(port, flags);

        return 0;
}

static void altera_uart_shutdown(struct uart_port *port)
{
        struct altera_uart *pp = container_of(port, struct altera_uart, port);
        unsigned long flags;

        uart_port_lock_irqsave(port, &flags);

        /* Disable all interrupts now */
        pp->imr = 0;
        altera_uart_update_ctrl_reg(pp);

        uart_port_unlock_irqrestore(port, flags);

        if (port->irq)
                free_irq(port->irq, port);
        else
                timer_delete_sync(&pp->tmr);
}

static const char *altera_uart_type(struct uart_port *port)
{
        return (port->type == PORT_ALTERA_UART) ? "Altera UART" : NULL;
}

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

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

static int altera_uart_verify_port(struct uart_port *port,
                                   struct serial_struct *ser)
{
        if ((ser->type != PORT_UNKNOWN) && (ser->type != PORT_ALTERA_UART))
                return -EINVAL;
        return 0;
}

#ifdef CONFIG_CONSOLE_POLL
static int altera_uart_poll_get_char(struct uart_port *port)
{
        while (!(altera_uart_readl(port, ALTERA_UART_STATUS_REG) &
                 ALTERA_UART_STATUS_RRDY_MSK))
                cpu_relax();

        return altera_uart_readl(port, ALTERA_UART_RXDATA_REG);
}

static void altera_uart_poll_put_char(struct uart_port *port, unsigned char c)
{
        while (!(altera_uart_readl(port, ALTERA_UART_STATUS_REG) &
                 ALTERA_UART_STATUS_TRDY_MSK))
                cpu_relax();

        altera_uart_writel(port, c, ALTERA_UART_TXDATA_REG);
}
#endif

/*
 *      Define the basic serial functions we support.
 */
static const struct uart_ops altera_uart_ops = {
        .tx_empty       = altera_uart_tx_empty,
        .get_mctrl      = altera_uart_get_mctrl,
        .set_mctrl      = altera_uart_set_mctrl,
        .start_tx       = altera_uart_start_tx,
        .stop_tx        = altera_uart_stop_tx,
        .stop_rx        = altera_uart_stop_rx,
        .break_ctl      = altera_uart_break_ctl,
        .startup        = altera_uart_startup,
        .shutdown       = altera_uart_shutdown,
        .set_termios    = altera_uart_set_termios,
        .type           = altera_uart_type,
        .request_port   = altera_uart_request_port,
        .release_port   = altera_uart_release_port,
        .config_port    = altera_uart_config_port,
        .verify_port    = altera_uart_verify_port,
#ifdef CONFIG_CONSOLE_POLL
        .poll_get_char  = altera_uart_poll_get_char,
        .poll_put_char  = altera_uart_poll_put_char,
#endif
};

static struct altera_uart altera_uart_ports[CONFIG_SERIAL_ALTERA_UART_MAXPORTS];

#if defined(CONFIG_SERIAL_ALTERA_UART_CONSOLE)

static void altera_uart_console_putc(struct uart_port *port, unsigned char c)
{
        while (!(altera_uart_readl(port, ALTERA_UART_STATUS_REG) &
                 ALTERA_UART_STATUS_TRDY_MSK))
                cpu_relax();

        altera_uart_writel(port, c, ALTERA_UART_TXDATA_REG);
}

static void altera_uart_console_write(struct console *co, const char *s,
                                      unsigned int count)
{
        struct uart_port *port = &(altera_uart_ports + co->index)->port;

        uart_console_write(port, s, count, altera_uart_console_putc);
}

static int __init altera_uart_console_setup(struct console *co, char *options)
{
        struct uart_port *port;
        int baud = CONFIG_SERIAL_ALTERA_UART_BAUDRATE;
        int bits = 8;
        int parity = 'n';
        int flow = 'n';

        if (co->index < 0 || co->index >= CONFIG_SERIAL_ALTERA_UART_MAXPORTS)
                return -EINVAL;
        port = &altera_uart_ports[co->index].port;
        if (!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 struct uart_driver altera_uart_driver;

static struct console altera_uart_console = {
        .name   = "ttyAL",
        .write  = altera_uart_console_write,
        .device = uart_console_device,
        .setup  = altera_uart_console_setup,
        .flags  = CON_PRINTBUFFER,
        .index  = -1,
        .data   = &altera_uart_driver,
};

static int __init altera_uart_console_init(void)
{
        register_console(&altera_uart_console);
        return 0;
}

console_initcall(altera_uart_console_init);

#define ALTERA_UART_CONSOLE     (&altera_uart_console)

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

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

static int __init altera_uart_earlycon_setup(struct earlycon_device *dev,
                                             const char *options)
{
        struct uart_port *port = &dev->port;

        if (!port->membase)
                return -ENODEV;

        /* Enable RX interrupts now */
        altera_uart_writel(port, ALTERA_UART_CONTROL_RRDY_MSK,
                           ALTERA_UART_CONTROL_REG);

        if (dev->baud) {
                unsigned int baudclk = port->uartclk / dev->baud;

                altera_uart_writel(port, baudclk, ALTERA_UART_DIVISOR_REG);
        }

        dev->con->write = altera_uart_earlycon_write;
        return 0;
}

OF_EARLYCON_DECLARE(uart, "altr,uart-1.0", altera_uart_earlycon_setup);

#else

#define ALTERA_UART_CONSOLE     NULL

#endif /* CONFIG_SERIAL_ALTERA_UART_CONSOLE */

/*
 *      Define the altera_uart UART driver structure.
 */
static struct uart_driver altera_uart_driver = {
        .owner          = THIS_MODULE,
        .driver_name    = KBUILD_MODNAME,
        .dev_name       = "ttyAL",
        .major          = SERIAL_ALTERA_MAJOR,
        .minor          = SERIAL_ALTERA_MINOR,
        .nr             = CONFIG_SERIAL_ALTERA_UART_MAXPORTS,
        .cons           = ALTERA_UART_CONSOLE,
};

static int altera_uart_probe(struct platform_device *pdev)
{
        struct altera_uart_platform_uart *platp = dev_get_platdata(&pdev->dev);
        struct uart_port *port;
        struct resource *res_mem;
        int i = pdev->id;
        int ret;

        /* if id is -1 scan for a free id and use that one */
        if (i == -1) {
                for (i = 0; i < CONFIG_SERIAL_ALTERA_UART_MAXPORTS; i++)
                        if (altera_uart_ports[i].port.mapbase == 0)
                                break;
        }

        if (i < 0 || i >= CONFIG_SERIAL_ALTERA_UART_MAXPORTS)
                return -EINVAL;

        port = &altera_uart_ports[i].port;

        res_mem = platform_get_resource(pdev, IORESOURCE_MEM, 0);
        if (res_mem)
                port->mapbase = res_mem->start;
        else if (platp)
                port->mapbase = platp->mapbase;
        else
                return -EINVAL;

        ret = platform_get_irq_optional(pdev, 0);
        if (ret < 0 && ret != -ENXIO)
                return ret;
        if (ret > 0)
                port->irq = ret;
        else if (platp)
                port->irq = platp->irq;

        /* Check platform data first so we can override device node data */
        if (platp)
                port->uartclk = platp->uartclk;
        else {
                ret = of_property_read_u32(pdev->dev.of_node, "clock-frequency",
                                           &port->uartclk);
                if (ret)
                        return ret;
        }

        port->membase = ioremap(port->mapbase, ALTERA_UART_SIZE);
        if (!port->membase)
                return -ENOMEM;

        if (platp)
                port->regshift = platp->bus_shift;
        else
                port->regshift = 0;

        port->line = i;
        port->type = PORT_ALTERA_UART;
        port->iotype = SERIAL_IO_MEM;
        port->ops = &altera_uart_ops;
        port->flags = UPF_BOOT_AUTOCONF;
        port->dev = &pdev->dev;

        platform_set_drvdata(pdev, port);

        uart_add_one_port(&altera_uart_driver, port);

        return 0;
}

static void altera_uart_remove(struct platform_device *pdev)
{
        struct uart_port *port = platform_get_drvdata(pdev);

        if (port) {
                uart_remove_one_port(&altera_uart_driver, port);
                port->mapbase = 0;
                iounmap(port->membase);
        }
}

#ifdef CONFIG_OF
static const struct of_device_id altera_uart_match[] = {
        { .compatible = "ALTR,uart-1.0", },
        { .compatible = "altr,uart-1.0", },
        {},
};
MODULE_DEVICE_TABLE(of, altera_uart_match);
#endif /* CONFIG_OF */

static struct platform_driver altera_uart_platform_driver = {
        .probe  = altera_uart_probe,
        .remove = altera_uart_remove,
        .driver = {
                .name           = KBUILD_MODNAME,
                .of_match_table = of_match_ptr(altera_uart_match),
        },
};

static int __init altera_uart_init(void)
{
        int rc;

        rc = uart_register_driver(&altera_uart_driver);
        if (rc)
                return rc;
        rc = platform_driver_register(&altera_uart_platform_driver);
        if (rc)
                uart_unregister_driver(&altera_uart_driver);
        return rc;
}

static void __exit altera_uart_exit(void)
{
        platform_driver_unregister(&altera_uart_platform_driver);
        uart_unregister_driver(&altera_uart_driver);
}

module_init(altera_uart_init);
module_exit(altera_uart_exit);

MODULE_DESCRIPTION("Altera UART driver");
MODULE_AUTHOR("Thomas Chou <thomas@wytron.com.tw>");
MODULE_LICENSE("GPL");
MODULE_ALIAS("platform:" KBUILD_MODNAME);
MODULE_ALIAS_CHARDEV_MAJOR(SERIAL_ALTERA_MAJOR);