arch/m68k/mac/oss.c

Source file repositories/reference/linux-study-clean/arch/m68k/mac/oss.c

File Facts

System
Linux kernel
Corpus path
arch/m68k/mac/oss.c
Extension
.c
Size
4594 bytes
Lines
189
Domain
Architecture Layer
Bucket
arch/m68k
Inferred role
Architecture Layer: implementation source
Status
source implementation candidate

Why This File Exists

CPU and platform-specific kernel glue: boot entry, traps, syscall entry, interrupts, page tables, context switch, and low-level barriers.

Dependency Surface

Detected Declarations

Annotated Snippet

if (events & irq_bit) {
			events &= ~irq_bit;
			generic_handle_irq(irq_num);
		}
		--irq_num;
		irq_bit >>= 1;
	} while (events);
}

static void oss_iopscc_irq(struct irq_desc *desc)
{
	generic_handle_irq(IRQ_MAC_SCC);
}

/*
 * 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_iopism_irq);
	irq_set_chained_handler(OSS_IRQLEV_SCSI,   oss_scsi_irq);
	irq_set_chained_handler(OSS_IRQLEV_NUBUS,  oss_nubus_irq);
	irq_set_chained_handler(OSS_IRQLEV_IOPSCC, oss_iopscc_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] = OSS_IRQLEV_VIA1;
}

/*
 * 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;

Annotation

Implementation Notes