// SPDX-License-Identifier: GPL-2.0-or-later
/*
        Mantis PCI bridge driver

        Copyright (C) Manu Abraham (abraham.manu@gmail.com)

*/

#include <linux/kernel.h>
#include <linux/spinlock.h>
#include <asm/io.h>

#include <linux/signal.h>
#include <linux/sched.h>
#include <linux/interrupt.h>
#include <linux/pci.h>

#include <media/dmxdev.h>
#include <media/dvbdev.h>
#include <media/dvb_demux.h>
#include <media/dvb_frontend.h>
#include <media/dvb_net.h>

#include "mantis_common.h"
#include "mantis_reg.h"
#include "mantis_uart.h"
#include "mantis_input.h"

struct mantis_uart_params {
        enum mantis_baud        baud_rate;
        enum mantis_parity      parity;
};

static struct {
        char string[7];
} rates[5] = {
        { "9600" },
        { "19200" },
        { "38400" },
        { "57600" },
        { "115200" }
};

static struct {
        char string[5];
} parity[3] = {
        { "NONE" },
        { "ODD" },
        { "EVEN" }
};

static void mantis_uart_read(struct mantis_pci *mantis)
{
        struct mantis_hwconfig *config = mantis->hwconfig;
        int i, scancode = 0, err = 0;

        /* get data */
        dprintk(MANTIS_DEBUG, 1, "UART Reading ...");
        for (i = 0; i < (config->bytes + 1); i++) {
                int data = mmread(MANTIS_UART_RXD);

                dprintk(MANTIS_DEBUG, 0, " <%02x>", data);

                scancode = (scancode << 8) | (data & 0x3f);
                err |= data;

                if (data & (1 << 7))
                        dprintk(MANTIS_ERROR, 1, "UART framing error");

                if (data & (1 << 6))
                        dprintk(MANTIS_ERROR, 1, "UART parity error");
        }
        dprintk(MANTIS_DEBUG, 0, "\n");

        if ((err & 0xC0) == 0)
                mantis_input_process(mantis, scancode);
}

static void mantis_uart_work(struct work_struct *work)
{
        struct mantis_pci *mantis = container_of(work, struct mantis_pci, uart_work);
        u32 stat;
        unsigned long timeout;

        stat = mmread(MANTIS_UART_STAT);

        if (stat & MANTIS_UART_RXFIFO_FULL)
                dprintk(MANTIS_ERROR, 1, "RX Fifo FULL");

        /*
         * MANTIS_UART_RXFIFO_DATA is only set if at least
         * config->bytes + 1 bytes are in the FIFO.
         */

        /* FIXME: is 10ms good enough ? */
        timeout = jiffies +  msecs_to_jiffies(10);
        while (stat & MANTIS_UART_RXFIFO_DATA) {
                mantis_uart_read(mantis);
                stat = mmread(MANTIS_UART_STAT);

                if (!time_is_after_jiffies(timeout))
                        break;
        }

        /* re-enable UART (RX) interrupt */
        mantis_unmask_ints(mantis, MANTIS_INT_IRQ1);
}

static int mantis_uart_setup(struct mantis_pci *mantis,
                             struct mantis_uart_params *params)
{
        u32 reg;

        mmwrite((mmread(MANTIS_UART_CTL) | (params->parity & 0x3)), MANTIS_UART_CTL);

        reg = mmread(MANTIS_UART_BAUD);

        switch (params->baud_rate) {
        case MANTIS_BAUD_9600:
                reg |= 0xd8;
                break;
        case MANTIS_BAUD_19200:
                reg |= 0x6c;
                break;
        case MANTIS_BAUD_38400:
                reg |= 0x36;
                break;
        case MANTIS_BAUD_57600:
                reg |= 0x23;
                break;
        case MANTIS_BAUD_115200:
                reg |= 0x11;
                break;
        default:
                return -EINVAL;
        }

        mmwrite(reg, MANTIS_UART_BAUD);

        return 0;
}

int mantis_uart_init(struct mantis_pci *mantis)
{
        struct mantis_hwconfig *config = mantis->hwconfig;
        struct mantis_uart_params params;

        /* default parity: */
        params.baud_rate = config->baud_rate;
        params.parity = config->parity;
        dprintk(MANTIS_INFO, 1, "Initializing UART @ %sbps parity:%s",
                rates[params.baud_rate].string,
                parity[params.parity].string);

        INIT_WORK(&mantis->uart_work, mantis_uart_work);

        /* disable interrupt */
        mmwrite(mmread(MANTIS_UART_CTL) & 0xffef, MANTIS_UART_CTL);

        mantis_uart_setup(mantis, &params);

        /* default 1 byte */
        mmwrite((mmread(MANTIS_UART_BAUD) | (config->bytes << 8)), MANTIS_UART_BAUD);

        /* flush buffer */
        mmwrite((mmread(MANTIS_UART_CTL) | MANTIS_UART_RXFLUSH), MANTIS_UART_CTL);

        /* enable interrupt */
        mmwrite(mmread(MANTIS_UART_CTL) | MANTIS_UART_RXINT, MANTIS_UART_CTL);
        mantis_unmask_ints(mantis, MANTIS_INT_IRQ1);

        schedule_work(&mantis->uart_work);
        dprintk(MANTIS_DEBUG, 1, "UART successfully initialized");

        return 0;
}
EXPORT_SYMBOL_GPL(mantis_uart_init);

void mantis_uart_exit(struct mantis_pci *mantis)
{
        /* disable interrupt */
        mantis_mask_ints(mantis, MANTIS_INT_IRQ1);
        mmwrite(mmread(MANTIS_UART_CTL) & 0xffef, MANTIS_UART_CTL);
        flush_work(&mantis->uart_work);
}
EXPORT_SYMBOL_GPL(mantis_uart_exit);