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/* SPDX-License-Identifier: GPL-2.0-only */
#include <arch/io.h>
#include <pc80/i8259.h>
#include <console/console.h>
/* Read the current PIC IRQ mask */
u16 pic_read_irq_mask(void)
{
u16 mask;
int i;
mask = inb(MASTER_PIC_OCW1) | (inb(SLAVE_PIC_OCW1) << 8);
printk(BIOS_DEBUG, "8259 PIC: OCW1 IRQ Mask: 0x%x\n", mask);
printk(BIOS_SPEW, "\tEnabled IRQs (0 = Unmasked, 1 = Masked off):\n"
"\t\tMaster\t\tSlave\n");
for (i = 0; i <= 7; i++) {
printk(BIOS_SPEW, "\t\tIRQ%X: %x\t\tIRQ%X: %x\n",
i, (mask >> i) & 1, i + 8, (mask >> (i + 8)) & 1);
}
return mask;
}
/*
* Write an IRQ mask to the PIC:
* IRQA is bit 0xA in the 16 bit bitmask (OCW1)
*/
void pic_write_irq_mask(u16 mask)
{
outb(mask, MASTER_PIC_OCW1);
outb(mask >> 8, SLAVE_PIC_OCW1);
}
/*
* The PIC IRQs default to masked off
* Allow specific IRQs to be enabled (1)
* or disabled by (0) the user
*/
void pic_irq_enable(u8 int_num, u8 mask)
{
pic_write_irq_mask(pic_read_irq_mask() & ~(mask << int_num));
pic_read_irq_mask();
}
void setup_i8259(void)
{
/* A write to ICW1 starts the Interrupt Controller Initialization
* Sequence. This implicitly causes the following to happen:
* - Interrupt Mask register is cleared
* - Priority 7 is assigned to IRQ7 input
* - Slave mode address is set to 7
* - Special mask mode is cleared
*
* We send the initialization sequence to both the master and
* slave i8259 controller.
*/
outb(ICW_SELECT|IC4, MASTER_PIC_ICW1);
outb(ICW_SELECT|IC4, SLAVE_PIC_ICW1);
/* Now the interrupt controller expects us to write to ICW2. */
outb(INT_VECTOR_MASTER | IRQ0, MASTER_PIC_ICW2);
outb(INT_VECTOR_SLAVE | IRQ8, SLAVE_PIC_ICW2);
/* Now the interrupt controller expects us to write to ICW3.
*
* The normal scenario is to set up cascading on IRQ2 on the master
* i8259 and assign the slave ID 2 to the slave i8259.
*/
outb(CASCADED_PIC, MASTER_PIC_ICW3);
outb(SLAVE_ID, SLAVE_PIC_ICW3);
/* Now the interrupt controller expects us to write to ICW4.
*
* We switch both i8259 to microprocessor mode because they're
* operating as part of an x86 architecture based chipset
*/
outb(MICROPROCESSOR_MODE, MASTER_PIC_ICW2);
outb(MICROPROCESSOR_MODE, SLAVE_PIC_ICW2);
/* Now clear the interrupts through OCW1.
* First we mask off all interrupts on the slave interrupt controller
* then we mask off all interrupts but interrupt 2 on the master
* controller. This way the cascading stays alive.
*/
outb(ALL_IRQS, SLAVE_PIC_OCW1);
outb(ALL_IRQS & ~IRQ2, MASTER_PIC_OCW1);
}
/**
* @brief Configure IRQ triggering in the i8259 compatible Interrupt Controller.
*
* Switch a certain interrupt to be level / edge triggered.
*
* @param int_num legacy interrupt number (3-7, 9-15)
* @param is_level_triggered 1 for level triggered interrupt, 0 for edge
* triggered interrupt
*/
void i8259_configure_irq_trigger(int int_num, int is_level_triggered)
{
u16 int_bits = inb(ELCR1) | (((u16)inb(ELCR2)) << 8);
if (is_level_triggered)
int_bits |= (1 << int_num);
else
int_bits &= ~(1 << int_num);
/* Write new values */
outb((u8)(int_bits & 0xff), ELCR1);
outb((u8)(int_bits >> 8), ELCR2);
#ifdef PARANOID_IRQ_TRIGGERS
/* Try reading back the new values. This seems like an error
* but it is not. */
if (inb(ELCR1) != (int_bits & 0xff)) {
printk(BIOS_ERR, "%s: lower order bits are wrong: want 0x%x, got 0x%x\n",
__func__, (int_bits & 0xff), inb(ELCR1));
}
if (inb(ELCR2) != (int_bits >> 8)) {
printk(BIOS_ERR, "%s: higher order bits are wrong: want 0x%x, got 0x%x\n",
__func__, (int_bits>>8), inb(ELCR2));
}
#endif
}
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