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/*
* Operating System Services (OSS) chip handling
* Written by Joshua M. Thompson (funaho@jurai.org)
*
*
* This chip is used in the IIfx in place of VIA #2. It acts like a fancy
* VIA chip with prorammable interrupt levels.
*
* 990502 (jmt) - Major rewrite for new interrupt architecture as well as some
* recent insights into OSS operational details.
* 990610 (jmt) - Now taking full advantage of the OSS. Interrupts are mapped
* to mostly match the A/UX interrupt scheme supported on the
* VIA side. Also added support for enabling the ISM irq again
* since we now have a functional IOP manager.
*/
#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/macintosh.h>
#include <asm/macints.h>
#include <asm/mac_via.h>
#include <asm/mac_oss.h>
int oss_present;
volatile struct mac_oss *oss;
/*
* Initialize the OSS
*
* The OSS "detection" code is actually in via_init() which is always called
* before us. Thus we can count on oss_present being valid on entry.
*/
void __init oss_init(void)
{
int i;
if (!oss_present) return;
oss = (struct mac_oss *) OSS_BASE;
/* Disable all interrupts. Unlike a VIA it looks like we */
/* do this by setting the source's interrupt level to zero. */
for (i = 0; i < OSS_NUM_SOURCES; i++)
oss->irq_level[i] = 0;
}
/*
* Initialize OSS for Nubus access
*/
void __init oss_nubus_init(void)
{
}
/*
* Handle miscellaneous OSS interrupts.
*/
static void oss_irq(struct irq_desc *desc)
{
int events = oss->irq_pending &
(OSS_IP_IOPSCC | OSS_IP_SCSI | OSS_IP_IOPISM);
if (events & OSS_IP_IOPSCC) {
oss->irq_pending &= ~OSS_IP_IOPSCC;
generic_handle_irq(IRQ_MAC_SCC);
}
if (events & OSS_IP_SCSI) {
oss->irq_pending &= ~OSS_IP_SCSI;
generic_handle_irq(IRQ_MAC_SCSI);
}
if (events & OSS_IP_IOPISM) {
oss->irq_pending &= ~OSS_IP_IOPISM;
generic_handle_irq(IRQ_MAC_ADB);
}
}
/*
* Nubus IRQ handler, OSS style
*
* Unlike the VIA/RBV this is on its own autovector interrupt level.
*/
static void oss_nubus_irq(struct irq_desc *desc)
{
int events, irq_bit, i;
events = oss->irq_pending & OSS_IP_NUBUS;
if (!events)
return;
/* There are only six slots on the OSS, not seven */
i = 6;
irq_bit = 0x40;
do {
--i;
irq_bit >>= 1;
if (events & irq_bit) {
oss->irq_pending &= ~irq_bit;
generic_handle_irq(NUBUS_SOURCE_BASE + i);
}
} while(events & (irq_bit - 1));
}
/*
* Register the OSS and NuBus interrupt dispatchers.
*
* This IRQ mapping is laid out with two things in mind: first, we try to keep
* things on their own levels to avoid having to do double-dispatches. Second,
* the levels match as closely as possible the alternate IRQ mapping mode (aka
* "A/UX mode") available on some VIA machines.
*/
#define OSS_IRQLEV_IOPISM IRQ_AUTO_1
#define OSS_IRQLEV_SCSI IRQ_AUTO_2
#define OSS_IRQLEV_NUBUS IRQ_AUTO_3
#define OSS_IRQLEV_IOPSCC IRQ_AUTO_4
#define OSS_IRQLEV_VIA1 IRQ_AUTO_6
void __init oss_register_interrupts(void)
{
irq_set_chained_handler(OSS_IRQLEV_IOPISM, oss_irq);
irq_set_chained_handler(OSS_IRQLEV_SCSI, oss_irq);
irq_set_chained_handler(OSS_IRQLEV_NUBUS, oss_nubus_irq);
irq_set_chained_handler(OSS_IRQLEV_IOPSCC, oss_irq);
irq_set_chained_handler(OSS_IRQLEV_VIA1, via1_irq);
/* OSS_VIA1 gets enabled here because it has no machspec interrupt. */
oss->irq_level[OSS_VIA1] = IRQ_AUTO_6;
}
/*
* Enable an OSS interrupt
*
* It looks messy but it's rather straightforward. The switch() statement
* just maps the machspec interrupt numbers to the right OSS interrupt
* source (if the OSS handles that interrupt) and then sets the interrupt
* level for that source to nonzero, thus enabling the interrupt.
*/
void oss_irq_enable(int irq) {
switch(irq) {
case IRQ_MAC_SCC:
oss->irq_level[OSS_IOPSCC] = OSS_IRQLEV_IOPSCC;
return;
case IRQ_MAC_ADB:
oss->irq_level[OSS_IOPISM] = OSS_IRQLEV_IOPISM;
return;
case IRQ_MAC_SCSI:
oss->irq_level[OSS_SCSI] = OSS_IRQLEV_SCSI;
return;
case IRQ_NUBUS_9:
case IRQ_NUBUS_A:
case IRQ_NUBUS_B:
case IRQ_NUBUS_C:
case IRQ_NUBUS_D:
case IRQ_NUBUS_E:
irq -= NUBUS_SOURCE_BASE;
oss->irq_level[irq] = OSS_IRQLEV_NUBUS;
return;
}
if (IRQ_SRC(irq) == 1)
via_irq_enable(irq);
}
/*
* Disable an OSS interrupt
*
* Same as above except we set the source's interrupt level to zero,
* to disable the interrupt.
*/
void oss_irq_disable(int irq) {
switch(irq) {
case IRQ_MAC_SCC:
oss->irq_level[OSS_IOPSCC] = 0;
return;
case IRQ_MAC_ADB:
oss->irq_level[OSS_IOPISM] = 0;
return;
case IRQ_MAC_SCSI:
oss->irq_level[OSS_SCSI] = 0;
return;
case IRQ_NUBUS_9:
case IRQ_NUBUS_A:
case IRQ_NUBUS_B:
case IRQ_NUBUS_C:
case IRQ_NUBUS_D:
case IRQ_NUBUS_E:
irq -= NUBUS_SOURCE_BASE;
oss->irq_level[irq] = 0;
return;
}
if (IRQ_SRC(irq) == 1)
via_irq_disable(irq);
}
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