| /* 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); |
| } |