arch/m68k/mac/psc.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  *      Apple Peripheral System Controller (PSC)
   4  *
   5  *      The PSC is used on the AV Macs to control IO functions not handled
   6  *      by the VIAs (Ethernet, DSP, SCC).
   7  *
   8  * TO DO:
   9  *
  10  * Try to figure out what's going on in pIFR5 and pIFR6. There seem to be
  11  * persisant interrupt conditions in those registers and I have no idea what
  12  * they are. Granted it doesn't affect since we're not enabling any interrupts
  13  * on those levels at the moment, but it would be nice to know. I have a feeling
  14  * they aren't actually interrupt lines but data lines (to the DSP?)
  15  */
  16
  17 #include <linux/types.h>
  18 #include <linux/kernel.h>
  19 #include <linux/mm.h>
  20 #include <linux/delay.h>
  21 #include <linux/init.h>
  22 #include <linux/irq.h>
  23
  24 #include <asm/traps.h>
  25 #include <asm/macintosh.h>
  26 #include <asm/macints.h>
  27 #include <asm/mac_psc.h>
  28
  29 #define DEBUG_PSC
  30
  31 volatile __u8 *psc;
  32 EXPORT_SYMBOL_GPL(psc);
  33
  34 /*
  35  * Debugging dump, used in various places to see what's going on.
  36  */
  37
  38 static void psc_debug_dump(void)
  39 {
  40         int     i;
  41
  42         if (!psc)
  43                 return;
  44
  45         for (i = 0x30 ; i < 0x70 ; i += 0x10) {
  46                 printk(KERN_DEBUG "PSC #%d:  IFR = 0x%02X IER = 0x%02X\n",
  47                         i >> 4,
  48                         (int) psc_read_byte(pIFRbase + i),
  49                         (int) psc_read_byte(pIERbase + i));
  50         }
  51 }
  52
  53 /*
  54  * Try to kill all DMA channels on the PSC. Not sure how this his
  55  * supposed to work; this is code lifted from macmace.c and then
  56  * expanded to cover what I think are the other 7 channels.
  57  */
  58
  59 static __init void psc_dma_die_die_die(void)
  60 {
  61         int i;
  62
  63         for (i = 0 ; i < 9 ; i++) {
  64                 psc_write_word(PSC_CTL_BASE + (i << 4), 0x8800);
  65                 psc_write_word(PSC_CTL_BASE + (i << 4), 0x1000);
  66                 psc_write_word(PSC_CMD_BASE + (i << 5), 0x1100);
  67                 psc_write_word(PSC_CMD_BASE + (i << 5) + 0x10, 0x1100);
  68         }
  69 }
  70
  71 /*
  72  * Initialize the PSC. For now this just involves shutting down all
  73  * interrupt sources using the IERs.
  74  */
  75
  76 void __init psc_init(void)
  77 {
  78         int i;
  79
  80         if (macintosh_config->ident != MAC_MODEL_C660
  81          && macintosh_config->ident != MAC_MODEL_Q840)
  82         {
  83                 psc = NULL;
  84                 return;
  85         }
  86
  87         /*
  88          * The PSC is always at the same spot, but using psc
  89          * keeps things consistent with the psc_xxxx functions.
  90          */
  91
  92         psc = (void *) PSC_BASE;
  93
  94         pr_debug("PSC detected at %p\n", psc);
  95
  96         psc_dma_die_die_die();
  97
  98 #ifdef DEBUG_PSC
  99         psc_debug_dump();
 100 #endif
 101         /*
 102          * Mask and clear all possible interrupts
 103          */
 104
 105         for (i = 0x30 ; i < 0x70 ; i += 0x10) {
 106                 psc_write_byte(pIERbase + i, 0x0F);
 107                 psc_write_byte(pIFRbase + i, 0x0F);
 108         }
 109 }
 110
 111 /*
 112  * PSC interrupt handler. It's a lot like the VIA interrupt handler.
 113  */
 114
 115 static void psc_irq(struct irq_desc *desc)
 116 {
 117         unsigned int offset = (unsigned int)irq_desc_get_handler_data(desc);
 118         unsigned int irq = irq_desc_get_irq(desc);
 119         int pIFR        = pIFRbase + offset;
 120         int pIER        = pIERbase + offset;
 121         int irq_num;
 122         unsigned char irq_bit, events;
 123
 124         events = psc_read_byte(pIFR) & psc_read_byte(pIER) & 0xF;
 125         if (!events)
 126                 return;
 127
 128         irq_num = irq << 3;
 129         irq_bit = 1;
 130         do {
 131                 if (events & irq_bit) {
 132                         psc_write_byte(pIFR, irq_bit);
 133                         generic_handle_irq(irq_num);
 134                 }
 135                 irq_num++;
 136                 irq_bit <<= 1;
 137         } while (events >= irq_bit);
 138 }
 139
 140 /*
 141  * Register the PSC interrupt dispatchers for autovector interrupts 3-6.
 142  */
 143
 144 void __init psc_register_interrupts(void)
 145 {
 146         irq_set_chained_handler_and_data(IRQ_AUTO_3, psc_irq, (void *)0x30);
 147         irq_set_chained_handler_and_data(IRQ_AUTO_4, psc_irq, (void *)0x40);
 148         irq_set_chained_handler_and_data(IRQ_AUTO_5, psc_irq, (void *)0x50);
 149         irq_set_chained_handler_and_data(IRQ_AUTO_6, psc_irq, (void *)0x60);
 150 }
 151
 152 void psc_irq_enable(int irq) {
 153         int irq_src     = IRQ_SRC(irq);
 154         int irq_idx     = IRQ_IDX(irq);
 155         int pIER        = pIERbase + (irq_src << 4);
 156
 157         psc_write_byte(pIER, (1 << irq_idx) | 0x80);
 158 }
 159
 160 void psc_irq_disable(int irq) {
 161         int irq_src     = IRQ_SRC(irq);
 162         int irq_idx     = IRQ_IDX(irq);
 163         int pIER        = pIERbase + (irq_src << 4);
 164
 165         psc_write_byte(pIER, 1 << irq_idx);
 166 }