// SPDX-License-Identifier: GPL-2.0-only
/*
 *      Apple Peripheral System Controller (PSC)
 *
 *      The PSC is used on the AV Macs to control IO functions not handled
 *      by the VIAs (Ethernet, DSP, SCC).
 *
 * TO DO:
 *
 * Try to figure out what's going on in pIFR5 and pIFR6. There seem to be
 * persisant interrupt conditions in those registers and I have no idea what
 * they are. Granted it doesn't affect since we're not enabling any interrupts
 * on those levels at the moment, but it would be nice to know. I have a feeling
 * they aren't actually interrupt lines but data lines (to the DSP?)
 */

#include <linux/types.h>
#include <linux/kernel.h>
#include <linux/mm.h>
#include <linux/delay.h>
#include <linux/init.h>
#include <linux/irq.h>

#include <asm/traps.h>
#include <asm/macintosh.h>
#include <asm/macints.h>
#include <asm/mac_psc.h>

#include "mac.h"

#define DEBUG_PSC

volatile __u8 *psc;
EXPORT_SYMBOL_GPL(psc);

/*
 * Debugging dump, used in various places to see what's going on.
 */

static void psc_debug_dump(void)
{
        int     i;

        if (!psc)
                return;

        for (i = 0x30 ; i < 0x70 ; i += 0x10) {
                printk(KERN_DEBUG "PSC #%d:  IFR = 0x%02X IER = 0x%02X\n",
                        i >> 4,
                        (int) psc_read_byte(pIFRbase + i),
                        (int) psc_read_byte(pIERbase + i));
        }
}

/*
 * Try to kill all DMA channels on the PSC. Not sure how this his
 * supposed to work; this is code lifted from macmace.c and then
 * expanded to cover what I think are the other 7 channels.
 */

static __init void psc_dma_die_die_die(void)
{
        int i;

        for (i = 0 ; i < 9 ; i++) {
                psc_write_word(PSC_CTL_BASE + (i << 4), 0x8800);
                psc_write_word(PSC_CTL_BASE + (i << 4), 0x1000);
                psc_write_word(PSC_CMD_BASE + (i << 5), 0x1100);
                psc_write_word(PSC_CMD_BASE + (i << 5) + 0x10, 0x1100);
        }
}

/*
 * Initialize the PSC. For now this just involves shutting down all
 * interrupt sources using the IERs.
 */

void __init psc_init(void)
{
        int i;

        if (macintosh_config->ident != MAC_MODEL_C660
         && macintosh_config->ident != MAC_MODEL_Q840)
        {
                psc = NULL;
                return;
        }

        /*
         * The PSC is always at the same spot, but using psc
         * keeps things consistent with the psc_xxxx functions.
         */

        psc = (void *) PSC_BASE;

        pr_debug("PSC detected at %p\n", psc);

        psc_dma_die_die_die();

#ifdef DEBUG_PSC
        psc_debug_dump();
#endif
        /*
         * Mask and clear all possible interrupts
         */

        for (i = 0x30 ; i < 0x70 ; i += 0x10) {
                psc_write_byte(pIERbase + i, 0x0F);
                psc_write_byte(pIFRbase + i, 0x0F);
        }
}

/*
 * PSC interrupt handler. It's a lot like the VIA interrupt handler.
 */

static void psc_irq(struct irq_desc *desc)
{
        unsigned int offset = (unsigned int)irq_desc_get_handler_data(desc);
        unsigned int irq = irq_desc_get_irq(desc);
        int pIFR        = pIFRbase + offset;
        int pIER        = pIERbase + offset;
        int irq_num;
        unsigned char irq_bit, events;

        events = psc_read_byte(pIFR) & psc_read_byte(pIER) & 0xF;
        if (!events)
                return;

        irq_num = irq << 3;
        irq_bit = 1;
        do {
                if (events & irq_bit) {
                        psc_write_byte(pIFR, irq_bit);
                        generic_handle_irq(irq_num);
                }
                irq_num++;
                irq_bit <<= 1;
        } while (events >= irq_bit);
}

/*
 * Register the PSC interrupt dispatchers for autovector interrupts 3-6.
 */

void __init psc_register_interrupts(void)
{
        irq_set_chained_handler_and_data(IRQ_AUTO_3, psc_irq, (void *)0x30);
        irq_set_chained_handler_and_data(IRQ_AUTO_4, psc_irq, (void *)0x40);
        irq_set_chained_handler_and_data(IRQ_AUTO_5, psc_irq, (void *)0x50);
        irq_set_chained_handler_and_data(IRQ_AUTO_6, psc_irq, (void *)0x60);
}

void psc_irq_enable(int irq) {
        int irq_src     = IRQ_SRC(irq);
        int irq_idx     = IRQ_IDX(irq);
        int pIER        = pIERbase + (irq_src << 4);

        psc_write_byte(pIER, (1 << irq_idx) | 0x80);
}

void psc_irq_disable(int irq) {
        int irq_src     = IRQ_SRC(irq);
        int irq_idx     = IRQ_IDX(irq);
        int pIER        = pIERbase + (irq_src << 4);

        psc_write_byte(pIER, 1 << irq_idx);
}