psc.c

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/*
 *  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/bootinfo.h>
#include <asm/macintosh.h>
#include <asm/macints.h>
#include <asm/mac_psc.h>

#define DEBUG_PSC

int psc_present;
volatile __u8 *psc;

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

static void psc_debug_dump(void)
{
    int i;

    if (!psc_present) return;
    for (i = 0x30 ; i < 0x70 ; i += 0x10) {
        printk("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 void psc_dma_die_die_die(void)
{
    int i;

    printk("Killing all PSC DMA channels...");
    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);
    }
    printk("done!\n");
}

/*
 * 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;
        psc_present = 0;
        return;
    }

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

    psc = (void *) PSC_BASE;
    psc_present = 1;

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

#ifdef DEBUG_IRQS
    printk("psc_irq: irq %u pIFR = 0x%02X pIER = 0x%02X\n",
        irq, (int) psc_read_byte(pIFR), (int) psc_read_byte(pIER));
#endif

    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(IRQ_AUTO_3, psc_irq);
    irq_set_handler_data(IRQ_AUTO_3, (void *)0x30);
    irq_set_chained_handler(IRQ_AUTO_4, psc_irq);
    irq_set_handler_data(IRQ_AUTO_4, (void *)0x40);
    irq_set_chained_handler(IRQ_AUTO_5, psc_irq);
    irq_set_handler_data(IRQ_AUTO_5, (void *)0x50);
    irq_set_chained_handler(IRQ_AUTO_6, psc_irq);
    irq_set_handler_data(IRQ_AUTO_6, (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);

#ifdef DEBUG_IRQUSE
    printk("psc_irq_enable(%d)\n", irq);
#endif
    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);

#ifdef DEBUG_IRQUSE
    printk("psc_irq_disable(%d)\n", irq);
#endif
    psc_write_byte(pIER, 1 << irq_idx);
}