// SPDX-License-Identifier: GPL-2.0-or-later
/*
 *      Low-level parallel-support for PC-style hardware integrated in the 
 *      LASI-Controller (on GSC-Bus) for HP-PARISC Workstations
 *
 *      (C) 1999-2001 by Helge Deller <deller@gmx.de>
 * 
 * based on parport_pc.c by 
 *          Grant Guenther <grant@torque.net>
 *          Phil Blundell <philb@gnu.org>
 *          Tim Waugh <tim@cyberelk.demon.co.uk>
 *          Jose Renau <renau@acm.org>
 *          David Campbell
 *          Andrea Arcangeli
 */

#undef DEBUG    /* undef for production */

#include <linux/module.h>
#include <linux/init.h>
#include <linux/delay.h>
#include <linux/errno.h>
#include <linux/interrupt.h>
#include <linux/ioport.h>
#include <linux/kernel.h>
#include <linux/slab.h>
#include <linux/pci.h>
#include <linux/sysctl.h>

#include <asm/io.h>
#include <linux/uaccess.h>
#include <asm/superio.h>

#include <linux/parport.h>
#include <asm/pdc.h>
#include <asm/parisc-device.h>
#include <asm/hardware.h>
#include "parport_gsc.h"


MODULE_AUTHOR("Helge Deller <deller@gmx.de>");
MODULE_DESCRIPTION("HP-PARISC PC-style parallel port driver");
MODULE_LICENSE("GPL");


/*
 * Clear TIMEOUT BIT in EPP MODE
 *
 * This is also used in SPP detection.
 */
static int clear_epp_timeout(struct parport *pb)
{
        unsigned char r;

        if (!(parport_gsc_read_status(pb) & 0x01))
                return 1;

        /* To clear timeout some chips require double read */
        parport_gsc_read_status(pb);
        r = parport_gsc_read_status(pb);
        parport_writeb (r | 0x01, STATUS (pb)); /* Some reset by writing 1 */
        parport_writeb (r & 0xfe, STATUS (pb)); /* Others by writing 0 */
        r = parport_gsc_read_status(pb);

        return !(r & 0x01);
}

/*
 * Access functions.
 *
 * Most of these aren't static because they may be used by the
 * parport_xxx_yyy macros.  extern __inline__ versions of several
 * of these are in parport_gsc.h.
 */

void parport_gsc_init_state(struct pardevice *dev, struct parport_state *s)
{
        s->u.pc.ctr = 0xc | (dev->irq_func ? 0x10 : 0x0);
}

void parport_gsc_save_state(struct parport *p, struct parport_state *s)
{
        s->u.pc.ctr = parport_readb (CONTROL (p));
}

void parport_gsc_restore_state(struct parport *p, struct parport_state *s)
{
        parport_writeb (s->u.pc.ctr, CONTROL (p));
}

struct parport_operations parport_gsc_ops = 
{
        .write_data     = parport_gsc_write_data,
        .read_data      = parport_gsc_read_data,

        .write_control  = parport_gsc_write_control,
        .read_control   = parport_gsc_read_control,
        .frob_control   = parport_gsc_frob_control,

        .read_status    = parport_gsc_read_status,

        .enable_irq     = parport_gsc_enable_irq,
        .disable_irq    = parport_gsc_disable_irq,

        .data_forward   = parport_gsc_data_forward,
        .data_reverse   = parport_gsc_data_reverse,

        .init_state     = parport_gsc_init_state,
        .save_state     = parport_gsc_save_state,
        .restore_state  = parport_gsc_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,
};

/* --- Mode detection ------------------------------------- */

/*
 * Checks for port existence, all ports support SPP MODE
 */
static int parport_SPP_supported(struct parport *pb)
{
        unsigned char r, w;

        /*
         * first clear an eventually pending EPP timeout 
         * I (sailer@ife.ee.ethz.ch) have an SMSC chipset
         * that does not even respond to SPP cycles if an EPP
         * timeout is pending
         */
        clear_epp_timeout(pb);

        /* Do a simple read-write test to make sure the port exists. */
        w = 0xc;
        parport_writeb (w, CONTROL (pb));

        /* Is there a control register that we can read from?  Some
         * ports don't allow reads, so read_control just returns a
         * software copy. Some ports _do_ allow reads, so bypass the
         * software copy here.  In addition, some bits aren't
         * writable. */
        r = parport_readb (CONTROL (pb));
        if ((r & 0xf) == w) {
                w = 0xe;
                parport_writeb (w, CONTROL (pb));
                r = parport_readb (CONTROL (pb));
                parport_writeb (0xc, CONTROL (pb));
                if ((r & 0xf) == w)
                        return PARPORT_MODE_PCSPP;
        }

        /* Try the data register.  The data lines aren't tri-stated at
         * this stage, so we expect back what we wrote. */
        w = 0xaa;
        parport_gsc_write_data (pb, w);
        r = parport_gsc_read_data (pb);
        if (r == w) {
                w = 0x55;
                parport_gsc_write_data (pb, w);
                r = parport_gsc_read_data (pb);
                if (r == w)
                        return PARPORT_MODE_PCSPP;
        }

        return 0;
}

/* Detect PS/2 support.
 *
 * Bit 5 (0x20) sets the PS/2 data direction; setting this high
 * allows us to read data from the data lines.  In theory we would get back
 * 0xff but any peripheral attached to the port may drag some or all of the
 * lines down to zero.  So if we get back anything that isn't the contents
 * of the data register we deem PS/2 support to be present. 
 *
 * Some SPP ports have "half PS/2" ability - you can't turn off the line
 * drivers, but an external peripheral with sufficiently beefy drivers of
 * its own can overpower them and assert its own levels onto the bus, from
 * where they can then be read back as normal.  Ports with this property
 * and the right type of device attached are likely to fail the SPP test,
 * (as they will appear to have stuck bits) and so the fact that they might
 * be misdetected here is rather academic. 
 */

static int parport_PS2_supported(struct parport *pb)
{
        int ok = 0;
  
        clear_epp_timeout(pb);

        /* try to tri-state the buffer */
        parport_gsc_data_reverse (pb);
        
        parport_gsc_write_data(pb, 0x55);
        if (parport_gsc_read_data(pb) != 0x55) ok++;

        parport_gsc_write_data(pb, 0xaa);
        if (parport_gsc_read_data(pb) != 0xaa) ok++;

        /* cancel input mode */
        parport_gsc_data_forward (pb);

        if (ok) {
                pb->modes |= PARPORT_MODE_TRISTATE;
        } else {
                struct parport_gsc_private *priv = pb->private_data;
                priv->ctr_writable &= ~0x20;
        }

        return ok;
}


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

static struct parport *parport_gsc_probe_port(unsigned long base,
                                       unsigned long base_hi, int irq,
                                       struct parisc_device *padev)
{
        struct parport_gsc_private *priv;
        struct parport_operations *ops;
        struct parport tmp;
        struct parport *p = &tmp;

        priv = kzalloc_obj(struct parport_gsc_private);
        if (!priv) {
                printk(KERN_DEBUG "parport (0x%lx): no memory!\n", base);
                return NULL;
        }
        ops = kmemdup(&parport_gsc_ops, sizeof(struct parport_operations),
                      GFP_KERNEL);
        if (!ops) {
                printk(KERN_DEBUG "parport (0x%lx): no memory for ops!\n",
                       base);
                kfree (priv);
                return NULL;
        }
        priv->ctr = 0xc;
        priv->ctr_writable = 0xff;
        p->base = base;
        p->base_hi = base_hi;
        p->irq = irq;
        p->modes = PARPORT_MODE_PCSPP | PARPORT_MODE_SAFEININT;
        p->ops = ops;
        p->private_data = priv;
        p->physport = p;
        if (!parport_SPP_supported (p)) {
                /* No port. */
                kfree (priv);
                kfree(ops);
                return NULL;
        }
        parport_PS2_supported (p);

        if (!(p = parport_register_port(base, PARPORT_IRQ_NONE,
                                        PARPORT_DMA_NONE, ops))) {
                kfree (priv);
                kfree (ops);
                return NULL;
        }

        p->dev = &padev->dev;
        p->base_hi = base_hi;
        p->modes = tmp.modes;
        p->size = (p->modes & PARPORT_MODE_EPP)?8:3;
        p->private_data = priv;

        pr_info("%s: PC-style at 0x%lx", p->name, p->base);
        p->irq = irq;
        if (p->irq == PARPORT_IRQ_AUTO) {
                p->irq = PARPORT_IRQ_NONE;
        }
        if (p->irq != PARPORT_IRQ_NONE)
                pr_cont(", irq %d", p->irq);

        pr_cont(" [");
#define printmode(x)                                                    \
do {                                                                    \
        if (p->modes & PARPORT_MODE_##x)                                \
                pr_cont("%s%s", f++ ? "," : "", #x);                    \
} while (0)
        {
                int f = 0;
                printmode(PCSPP);
                printmode(TRISTATE);
                printmode(COMPAT);
                printmode(EPP);
//              printmode(ECP);
//              printmode(DMA);
        }
#undef printmode
        pr_cont("]\n");

        if (p->irq != PARPORT_IRQ_NONE) {
                if (request_irq (p->irq, parport_irq_handler,
                                 0, p->name, p)) {
                        pr_warn("%s: irq %d in use, resorting to polled operation\n",
                                p->name, p->irq);
                        p->irq = PARPORT_IRQ_NONE;
                }
        }

        /* Done probing.  Now put the port into a sensible start-up state. */

        parport_gsc_write_data(p, 0);
        parport_gsc_data_forward (p);

        /* Now that we've told the sharing engine about the port, and
           found out its characteristics, let the high-level drivers
           know about it. */
        parport_announce_port (p);

        return p;
}


#define PARPORT_GSC_OFFSET 0x800

static int parport_count;

static int __init parport_init_chip(struct parisc_device *dev)
{
        struct parport *p;
        unsigned long port;

        if (!dev->irq) {
                pr_warn("IRQ not found for parallel device at 0x%llx\n",
                        (unsigned long long)dev->hpa.start);
                return -ENODEV;
        }

        port = dev->hpa.start + PARPORT_GSC_OFFSET;
        
        /* some older machines with ASP-chip don't support
         * the enhanced parport modes.
         */
        if (boot_cpu_data.cpu_type > pcxt && !pdc_add_valid(port+4)) {

                /* Initialize bidirectional-mode (0x10) & data-tranfer-mode #1 (0x20) */
                pr_info("%s: initialize bidirectional-mode\n", __func__);
                parport_writeb ( (0x10 + 0x20), port + 4);

        } else {
                pr_info("%s: enhanced parport-modes not supported\n", __func__);
        }
        
        p = parport_gsc_probe_port(port, 0, dev->irq, dev);
        if (p)
                parport_count++;
        dev_set_drvdata(&dev->dev, p);

        return 0;
}

static void __exit parport_remove_chip(struct parisc_device *dev)
{
        struct parport *p = dev_get_drvdata(&dev->dev);
        if (p) {
                struct parport_operations *ops = p->ops;
                parport_remove_port(p);
                if (p->irq != PARPORT_IRQ_NONE)
                        free_irq(p->irq, p);
                kfree (p->private_data);
                parport_put_port(p);
                kfree (ops); /* hope no-one cached it */
        }
}

static const struct parisc_device_id parport_tbl[] __initconst = {
        { HPHW_FIO, HVERSION_REV_ANY_ID, HVERSION_ANY_ID, 0x74 },
        { 0, }
};

MODULE_DEVICE_TABLE(parisc, parport_tbl);

static struct parisc_driver parport_driver __refdata = {
        .name           = "Parallel",
        .id_table       = parport_tbl,
        .probe          = parport_init_chip,
        .remove         = __exit_p(parport_remove_chip),
};

static int parport_gsc_init(void)
{
        return register_parisc_driver(&parport_driver);
}

static void parport_gsc_exit(void)
{
        unregister_parisc_driver(&parport_driver);
}

module_init(parport_gsc_init);
module_exit(parport_gsc_exit);