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psc.c

/*
 *    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 <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;

irqreturn_t psc_irq(int, void *);

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

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.
 */

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 consisant 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);
      }
}

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

void __init psc_register_interrupts(void)
{
      request_irq(IRQ_AUTO_3, psc_irq, 0, "psc3", (void *) 0x30);
      request_irq(IRQ_AUTO_4, psc_irq, 0, "psc4", (void *) 0x40);
      request_irq(IRQ_AUTO_5, psc_irq, 0, "psc5", (void *) 0x50);
      request_irq(IRQ_AUTO_6, psc_irq, 0, "psc6", (void *) 0x60);
}

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

irqreturn_t psc_irq(int irq, void *dev_id)
{
      int pIFR    = pIFRbase + ((int) dev_id);
      int pIER    = pIERbase + ((int) dev_id);
      int irq_num;
      unsigned char irq_bit, events;

#ifdef DEBUG_IRQS
      printk("psc_irq: irq %d 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_NONE;

      irq_num = irq << 3;
      irq_bit = 1;
      do {
            if (events & irq_bit) {
                  psc_write_byte(pIFR, irq_bit);
                  m68k_handle_int(irq_num);
            }
            irq_num++;
            irq_bit <<= 1;
      } while (events >= irq_bit);
      return IRQ_HANDLED;
}

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);
}

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

      psc_write_byte(pIFR, 1 << irq_idx);
}

int psc_irq_pending(int irq)
{
      int irq_src = IRQ_SRC(irq);
      int irq_idx = IRQ_IDX(irq);
      int pIFR    = pIERbase + (irq_src << 4);

      return psc_read_byte(pIFR) & (1 << irq_idx);
}

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