// SPDX-License-Identifier: GPL-2.0-only
/* Low-level parallel port routines for the Amiga built-in port
 *
 * Author: Joerg Dorchain <joerg@dorchain.net>
 *
 * This is a complete rewrite of the code, but based heaviy upon the old
 * lp_intern. code.
 *
 * The built-in Amiga parallel port provides one port at a fixed address
 * with 8 bidirectional data lines (D0 - D7) and 3 bidirectional status
 * lines (BUSY, POUT, SEL), 1 output control line /STROBE (raised automatically
 * in hardware when the data register is accessed), and 1 input control line
 * /ACK, able to cause an interrupt, but both not directly settable by
 * software.
 */

#include <linux/module.h>
#include <linux/init.h>
#include <linux/parport.h>
#include <linux/ioport.h>
#include <linux/interrupt.h>
#include <linux/platform_device.h>

#include <asm/setup.h>
#include <asm/amigahw.h>
#include <asm/irq.h>
#include <asm/io.h>
#include <asm/amigaints.h>

#undef DEBUG

static void amiga_write_data(struct parport *p, unsigned char data)
{
        pr_debug("write_data %c\n", data);
        /* Triggers also /STROBE. This behavior cannot be changed */
        ciaa.prb = data;
        mb();
}

static unsigned char amiga_read_data(struct parport *p)
{
        /* Triggers also /STROBE. This behavior cannot be changed */
        return ciaa.prb;
}

static unsigned char control_amiga_to_pc(unsigned char control)
{
        return PARPORT_CONTROL_SELECT |
              PARPORT_CONTROL_AUTOFD | PARPORT_CONTROL_STROBE;
        /* fake value: interrupt enable, select in, no reset,
        no autolf, no strobe - seems to be closest the wiring diagram */
}

static void amiga_write_control(struct parport *p, unsigned char control)
{
        pr_debug("write_control %02x\n", control);
        /* No implementation possible */
}
        
static unsigned char amiga_read_control( struct parport *p)
{
        pr_debug("read_control\n");
        return control_amiga_to_pc(0);
}

static unsigned char amiga_frob_control( struct parport *p, unsigned char mask, unsigned char val)
{
        unsigned char old;

        pr_debug("frob_control mask %02x, value %02x\n", mask, val);
        old = amiga_read_control(p);
        amiga_write_control(p, (old & ~mask) ^ val);
        return old;
}

static unsigned char status_amiga_to_pc(unsigned char status)
{
        unsigned char ret = PARPORT_STATUS_BUSY | PARPORT_STATUS_ACK | PARPORT_STATUS_ERROR;

        if (status & 1) /* Busy */
                ret &= ~PARPORT_STATUS_BUSY;
        if (status & 2) /* PaperOut */
                ret |= PARPORT_STATUS_PAPEROUT;
        if (status & 4) /* Selected */
                ret |= PARPORT_STATUS_SELECT;
        /* the rest is not connected or handled autonomously in hardware */

        return ret;
}

static unsigned char amiga_read_status(struct parport *p)
{
        unsigned char status;

        status = status_amiga_to_pc(ciab.pra & 7);
        pr_debug("read_status %02x\n", status);
        return status;
}

static void amiga_enable_irq(struct parport *p)
{
        enable_irq(IRQ_AMIGA_CIAA_FLG);
}

static void amiga_disable_irq(struct parport *p)
{
        disable_irq(IRQ_AMIGA_CIAA_FLG);
}

static void amiga_data_forward(struct parport *p)
{
        pr_debug("forward\n");
        ciaa.ddrb = 0xff; /* all pins output */
        mb();
}

static void amiga_data_reverse(struct parport *p)
{
        pr_debug("reverse\n");
        ciaa.ddrb = 0; /* all pins input */
        mb();
}

static void amiga_init_state(struct pardevice *dev, struct parport_state *s)
{
        s->u.amiga.data = 0;
        s->u.amiga.datadir = 255;
        s->u.amiga.status = 0;
        s->u.amiga.statusdir = 0;
}

static void amiga_save_state(struct parport *p, struct parport_state *s)
{
        mb();
        s->u.amiga.data = ciaa.prb;
        s->u.amiga.datadir = ciaa.ddrb;
        s->u.amiga.status = ciab.pra & 7;
        s->u.amiga.statusdir = ciab.ddra & 7;
        mb();
}

static void amiga_restore_state(struct parport *p, struct parport_state *s)
{
        mb();
        ciaa.prb = s->u.amiga.data;
        ciaa.ddrb = s->u.amiga.datadir;
        ciab.pra |= (ciab.pra & 0xf8) | s->u.amiga.status;
        ciab.ddra |= (ciab.ddra & 0xf8) | s->u.amiga.statusdir;
        mb();
}

static struct parport_operations pp_amiga_ops = {
        .write_data     = amiga_write_data,
        .read_data      = amiga_read_data,

        .write_control  = amiga_write_control,
        .read_control   = amiga_read_control,
        .frob_control   = amiga_frob_control,

        .read_status    = amiga_read_status,

        .enable_irq     = amiga_enable_irq,
        .disable_irq    = amiga_disable_irq,

        .data_forward   = amiga_data_forward,
        .data_reverse   = amiga_data_reverse,

        .init_state     = amiga_init_state,
        .save_state     = amiga_save_state,
        .restore_state  = amiga_restore_state,

        .epp_write_data = parport_ieee1284_epp_write_data,
        .epp_read_data  = parport_ieee1284_epp_read_data,
        .epp_write_addr = parport_ieee1284_epp_write_addr,
        .epp_read_addr  = parport_ieee1284_epp_read_addr,

        .ecp_write_data = parport_ieee1284_ecp_write_data,
        .ecp_read_data  = parport_ieee1284_ecp_read_data,
        .ecp_write_addr = parport_ieee1284_ecp_write_addr,

        .compat_write_data      = parport_ieee1284_write_compat,
        .nibble_read_data       = parport_ieee1284_read_nibble,
        .byte_read_data         = parport_ieee1284_read_byte,

        .owner          = THIS_MODULE,
};

/* ----------- Initialisation code --------------------------------- */

static int __init amiga_parallel_probe(struct platform_device *pdev)
{
        struct parport *p;
        int err;

        ciaa.ddrb = 0xff;
        ciab.ddra &= 0xf8;
        mb();

        p = parport_register_port((unsigned long)&ciaa.prb, IRQ_AMIGA_CIAA_FLG,
                                   PARPORT_DMA_NONE, &pp_amiga_ops);
        if (!p)
                return -EBUSY;

        err = request_irq(IRQ_AMIGA_CIAA_FLG, parport_irq_handler, 0, p->name,
                          p);
        if (err)
                goto out_irq;

        pr_info("%s: Amiga built-in port using irq\n", p->name);
        /* XXX: set operating mode */
        parport_announce_port(p);

        platform_set_drvdata(pdev, p);

        return 0;

out_irq:
        parport_put_port(p);
        return err;
}

static void __exit amiga_parallel_remove(struct platform_device *pdev)
{
        struct parport *port = platform_get_drvdata(pdev);

        parport_remove_port(port);
        if (port->irq != PARPORT_IRQ_NONE)
                free_irq(IRQ_AMIGA_CIAA_FLG, port);
        parport_put_port(port);
}

/*
 * amiga_parallel_remove() lives in .exit.text. For drivers registered via
 * module_platform_driver_probe() this is ok because they cannot get unbound at
 * runtime. So mark the driver struct with __refdata to prevent modpost
 * triggering a section mismatch warning.
 */
static struct platform_driver amiga_parallel_driver __refdata = {
        .remove = __exit_p(amiga_parallel_remove),
        .driver   = {
                .name   = "amiga-parallel",
        },
};

module_platform_driver_probe(amiga_parallel_driver, amiga_parallel_probe);

MODULE_AUTHOR("Joerg Dorchain <joerg@dorchain.net>");
MODULE_DESCRIPTION("Parport Driver for Amiga builtin Port");
MODULE_LICENSE("GPL");
MODULE_ALIAS("platform:amiga-parallel");