// SPDX-License-Identifier: GPL-2.0
/*
 * SGI IOC3 8250 UART driver
 *
 * Copyright (C) 2019 Thomas Bogendoerfer <tbogendoerfer@suse.de>
 *
 * based on code Copyright (C) 2005 Stanislaw Skowronek <skylark@unaligned.org>
 *               Copyright (C) 2014 Joshua Kinard <linux@kumba.dev>
 */

#include <linux/module.h>
#include <linux/errno.h>
#include <linux/io.h>
#include <linux/platform_device.h>

#include "8250.h"

#define IOC3_UARTCLK (22000000 / 3)

struct ioc3_8250_data {
        int line;
};

static u32 ioc3_serial_in(struct uart_port *p, unsigned int offset)
{
        return readb(p->membase + (offset ^ 3));
}

static void ioc3_serial_out(struct uart_port *p, unsigned int offset, u32 value)
{
        writeb(value, p->membase + (offset ^ 3));
}

static int serial8250_ioc3_probe(struct platform_device *pdev)
{
        struct ioc3_8250_data *data;
        struct uart_8250_port up;
        struct resource *r;
        void __iomem *membase;
        int irq, line;

        r = platform_get_resource(pdev, IORESOURCE_MEM, 0);
        if (!r)
                return -ENODEV;

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

        membase = devm_ioremap(&pdev->dev, r->start, resource_size(r));
        if (!membase)
                return -ENOMEM;

        irq = platform_get_irq(pdev, 0);
        if (irq < 0)
                irq = 0; /* no interrupt -> use polling */

        /* Register serial ports with 8250.c */
        memset(&up, 0, sizeof(struct uart_8250_port));
        up.port.iotype = UPIO_MEM;
        up.port.uartclk = IOC3_UARTCLK;
        up.port.type = PORT_16550A;
        up.port.irq = irq;
        up.port.flags = (UPF_BOOT_AUTOCONF | UPF_SHARE_IRQ);
        up.port.dev = &pdev->dev;
        up.port.membase = membase;
        up.port.mapbase = r->start;
        up.port.serial_in = ioc3_serial_in;
        up.port.serial_out = ioc3_serial_out;
        line = serial8250_register_8250_port(&up);
        if (line < 0)
                return line;

        platform_set_drvdata(pdev, data);
        return 0;
}

static void serial8250_ioc3_remove(struct platform_device *pdev)
{
        struct ioc3_8250_data *data = platform_get_drvdata(pdev);

        serial8250_unregister_port(data->line);
}

static struct platform_driver serial8250_ioc3_driver = {
        .probe  = serial8250_ioc3_probe,
        .remove = serial8250_ioc3_remove,
        .driver = {
                .name = "ioc3-serial8250",
        }
};

module_platform_driver(serial8250_ioc3_driver);

MODULE_AUTHOR("Thomas Bogendoerfer <tbogendoerfer@suse.de>");
MODULE_DESCRIPTION("SGI IOC3 8250 UART driver");
MODULE_LICENSE("GPL");