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Diffstat (limited to '')
| -rw-r--r-- | drivers/irqchip/irq-i8259.c | 361 |
1 files changed, 361 insertions, 0 deletions
diff --git a/drivers/irqchip/irq-i8259.c b/drivers/irqchip/irq-i8259.c new file mode 100644 index 000000000..b70ce0d3c --- /dev/null +++ b/drivers/irqchip/irq-i8259.c @@ -0,0 +1,361 @@ +/* + * This file is subject to the terms and conditions of the GNU General Public + * License. See the file "COPYING" in the main directory of this archive + * for more details. + * + * Code to handle x86 style IRQs plus some generic interrupt stuff. + * + * Copyright (C) 1992 Linus Torvalds + * Copyright (C) 1994 - 2000 Ralf Baechle + */ +#include <linux/delay.h> +#include <linux/init.h> +#include <linux/ioport.h> +#include <linux/interrupt.h> +#include <linux/irqchip.h> +#include <linux/irqdomain.h> +#include <linux/kernel.h> +#include <linux/of_irq.h> +#include <linux/spinlock.h> +#include <linux/syscore_ops.h> +#include <linux/irq.h> + +#include <asm/i8259.h> +#include <asm/io.h> + +/* + * This is the 'legacy' 8259A Programmable Interrupt Controller, + * present in the majority of PC/AT boxes. + * plus some generic x86 specific things if generic specifics makes + * any sense at all. + * this file should become arch/i386/kernel/irq.c when the old irq.c + * moves to arch independent land + */ + +static int i8259A_auto_eoi = -1; +DEFINE_RAW_SPINLOCK(i8259A_lock); +static void disable_8259A_irq(struct irq_data *d); +static void enable_8259A_irq(struct irq_data *d); +static void mask_and_ack_8259A(struct irq_data *d); +static void init_8259A(int auto_eoi); +static int (*i8259_poll)(void) = i8259_irq; + +static struct irq_chip i8259A_chip = { + .name = "XT-PIC", + .irq_mask = disable_8259A_irq, + .irq_disable = disable_8259A_irq, + .irq_unmask = enable_8259A_irq, + .irq_mask_ack = mask_and_ack_8259A, +}; + +/* + * 8259A PIC functions to handle ISA devices: + */ + +void i8259_set_poll(int (*poll)(void)) +{ + i8259_poll = poll; +} + +/* + * This contains the irq mask for both 8259A irq controllers, + */ +static unsigned int cached_irq_mask = 0xffff; + +#define cached_master_mask (cached_irq_mask) +#define cached_slave_mask (cached_irq_mask >> 8) + +static void disable_8259A_irq(struct irq_data *d) +{ + unsigned int mask, irq = d->irq - I8259A_IRQ_BASE; + unsigned long flags; + + mask = 1 << irq; + raw_spin_lock_irqsave(&i8259A_lock, flags); + cached_irq_mask |= mask; + if (irq & 8) + outb(cached_slave_mask, PIC_SLAVE_IMR); + else + outb(cached_master_mask, PIC_MASTER_IMR); + raw_spin_unlock_irqrestore(&i8259A_lock, flags); +} + +static void enable_8259A_irq(struct irq_data *d) +{ + unsigned int mask, irq = d->irq - I8259A_IRQ_BASE; + unsigned long flags; + + mask = ~(1 << irq); + raw_spin_lock_irqsave(&i8259A_lock, flags); + cached_irq_mask &= mask; + if (irq & 8) + outb(cached_slave_mask, PIC_SLAVE_IMR); + else + outb(cached_master_mask, PIC_MASTER_IMR); + raw_spin_unlock_irqrestore(&i8259A_lock, flags); +} + +void make_8259A_irq(unsigned int irq) +{ + disable_irq_nosync(irq); + irq_set_chip_and_handler(irq, &i8259A_chip, handle_level_irq); + enable_irq(irq); +} + +/* + * This function assumes to be called rarely. Switching between + * 8259A registers is slow. + * This has to be protected by the irq controller spinlock + * before being called. + */ +static inline int i8259A_irq_real(unsigned int irq) +{ + int value; + int irqmask = 1 << irq; + + if (irq < 8) { + outb(0x0B, PIC_MASTER_CMD); /* ISR register */ + value = inb(PIC_MASTER_CMD) & irqmask; + outb(0x0A, PIC_MASTER_CMD); /* back to the IRR register */ + return value; + } + outb(0x0B, PIC_SLAVE_CMD); /* ISR register */ + value = inb(PIC_SLAVE_CMD) & (irqmask >> 8); + outb(0x0A, PIC_SLAVE_CMD); /* back to the IRR register */ + return value; +} + +/* + * Careful! The 8259A is a fragile beast, it pretty + * much _has_ to be done exactly like this (mask it + * first, _then_ send the EOI, and the order of EOI + * to the two 8259s is important! + */ +static void mask_and_ack_8259A(struct irq_data *d) +{ + unsigned int irqmask, irq = d->irq - I8259A_IRQ_BASE; + unsigned long flags; + + irqmask = 1 << irq; + raw_spin_lock_irqsave(&i8259A_lock, flags); + /* + * Lightweight spurious IRQ detection. We do not want + * to overdo spurious IRQ handling - it's usually a sign + * of hardware problems, so we only do the checks we can + * do without slowing down good hardware unnecessarily. + * + * Note that IRQ7 and IRQ15 (the two spurious IRQs + * usually resulting from the 8259A-1|2 PICs) occur + * even if the IRQ is masked in the 8259A. Thus we + * can check spurious 8259A IRQs without doing the + * quite slow i8259A_irq_real() call for every IRQ. + * This does not cover 100% of spurious interrupts, + * but should be enough to warn the user that there + * is something bad going on ... + */ + if (cached_irq_mask & irqmask) + goto spurious_8259A_irq; + cached_irq_mask |= irqmask; + +handle_real_irq: + if (irq & 8) { + inb(PIC_SLAVE_IMR); /* DUMMY - (do we need this?) */ + outb(cached_slave_mask, PIC_SLAVE_IMR); + outb(0x60+(irq&7), PIC_SLAVE_CMD);/* 'Specific EOI' to slave */ + outb(0x60+PIC_CASCADE_IR, PIC_MASTER_CMD); /* 'Specific EOI' to master-IRQ2 */ + } else { + inb(PIC_MASTER_IMR); /* DUMMY - (do we need this?) */ + outb(cached_master_mask, PIC_MASTER_IMR); + outb(0x60+irq, PIC_MASTER_CMD); /* 'Specific EOI to master */ + } + raw_spin_unlock_irqrestore(&i8259A_lock, flags); + return; + +spurious_8259A_irq: + /* + * this is the slow path - should happen rarely. + */ + if (i8259A_irq_real(irq)) + /* + * oops, the IRQ _is_ in service according to the + * 8259A - not spurious, go handle it. + */ + goto handle_real_irq; + + { + static int spurious_irq_mask; + /* + * At this point we can be sure the IRQ is spurious, + * lets ACK and report it. [once per IRQ] + */ + if (!(spurious_irq_mask & irqmask)) { + printk(KERN_DEBUG "spurious 8259A interrupt: IRQ%d.\n", irq); + spurious_irq_mask |= irqmask; + } + atomic_inc(&irq_err_count); + /* + * Theoretically we do not have to handle this IRQ, + * but in Linux this does not cause problems and is + * simpler for us. + */ + goto handle_real_irq; + } +} + +static void i8259A_resume(void) +{ + if (i8259A_auto_eoi >= 0) + init_8259A(i8259A_auto_eoi); +} + +static void i8259A_shutdown(void) +{ + /* Put the i8259A into a quiescent state that + * the kernel initialization code can get it + * out of. + */ + if (i8259A_auto_eoi >= 0) { + outb(0xff, PIC_MASTER_IMR); /* mask all of 8259A-1 */ + outb(0xff, PIC_SLAVE_IMR); /* mask all of 8259A-2 */ + } +} + +static struct syscore_ops i8259_syscore_ops = { + .resume = i8259A_resume, + .shutdown = i8259A_shutdown, +}; + +static void init_8259A(int auto_eoi) +{ + unsigned long flags; + + i8259A_auto_eoi = auto_eoi; + + raw_spin_lock_irqsave(&i8259A_lock, flags); + + outb(0xff, PIC_MASTER_IMR); /* mask all of 8259A-1 */ + outb(0xff, PIC_SLAVE_IMR); /* mask all of 8259A-2 */ + + /* + * outb_p - this has to work on a wide range of PC hardware. + */ + outb_p(0x11, PIC_MASTER_CMD); /* ICW1: select 8259A-1 init */ + outb_p(I8259A_IRQ_BASE + 0, PIC_MASTER_IMR); /* ICW2: 8259A-1 IR0 mapped to I8259A_IRQ_BASE + 0x00 */ + outb_p(1U << PIC_CASCADE_IR, PIC_MASTER_IMR); /* 8259A-1 (the master) has a slave on IR2 */ + if (auto_eoi) /* master does Auto EOI */ + outb_p(MASTER_ICW4_DEFAULT | PIC_ICW4_AEOI, PIC_MASTER_IMR); + else /* master expects normal EOI */ + outb_p(MASTER_ICW4_DEFAULT, PIC_MASTER_IMR); + + outb_p(0x11, PIC_SLAVE_CMD); /* ICW1: select 8259A-2 init */ + outb_p(I8259A_IRQ_BASE + 8, PIC_SLAVE_IMR); /* ICW2: 8259A-2 IR0 mapped to I8259A_IRQ_BASE + 0x08 */ + outb_p(PIC_CASCADE_IR, PIC_SLAVE_IMR); /* 8259A-2 is a slave on master's IR2 */ + outb_p(SLAVE_ICW4_DEFAULT, PIC_SLAVE_IMR); /* (slave's support for AEOI in flat mode is to be investigated) */ + if (auto_eoi) + /* + * In AEOI mode we just have to mask the interrupt + * when acking. + */ + i8259A_chip.irq_mask_ack = disable_8259A_irq; + else + i8259A_chip.irq_mask_ack = mask_and_ack_8259A; + + udelay(100); /* wait for 8259A to initialize */ + + outb(cached_master_mask, PIC_MASTER_IMR); /* restore master IRQ mask */ + outb(cached_slave_mask, PIC_SLAVE_IMR); /* restore slave IRQ mask */ + + raw_spin_unlock_irqrestore(&i8259A_lock, flags); +} + +static struct resource pic1_io_resource = { + .name = "pic1", + .start = PIC_MASTER_CMD, + .end = PIC_MASTER_IMR, + .flags = IORESOURCE_IO | IORESOURCE_BUSY +}; + +static struct resource pic2_io_resource = { + .name = "pic2", + .start = PIC_SLAVE_CMD, + .end = PIC_SLAVE_IMR, + .flags = IORESOURCE_IO | IORESOURCE_BUSY +}; + +static int i8259A_irq_domain_map(struct irq_domain *d, unsigned int virq, + irq_hw_number_t hw) +{ + irq_set_chip_and_handler(virq, &i8259A_chip, handle_level_irq); + irq_set_probe(virq); + return 0; +} + +static const struct irq_domain_ops i8259A_ops = { + .map = i8259A_irq_domain_map, + .xlate = irq_domain_xlate_onecell, +}; + +/* + * On systems with i8259-style interrupt controllers we assume for + * driver compatibility reasons interrupts 0 - 15 to be the i8259 + * interrupts even if the hardware uses a different interrupt numbering. + */ +struct irq_domain * __init __init_i8259_irqs(struct device_node *node) +{ + /* + * PIC_CASCADE_IR is cascade interrupt to second interrupt controller + */ + int irq = I8259A_IRQ_BASE + PIC_CASCADE_IR; + struct irq_domain *domain; + + insert_resource(&ioport_resource, &pic1_io_resource); + insert_resource(&ioport_resource, &pic2_io_resource); + + init_8259A(0); + + domain = irq_domain_add_legacy(node, 16, I8259A_IRQ_BASE, 0, + &i8259A_ops, NULL); + if (!domain) + panic("Failed to add i8259 IRQ domain"); + + if (request_irq(irq, no_action, IRQF_NO_THREAD, "cascade", NULL)) + pr_err("Failed to register cascade interrupt\n"); + register_syscore_ops(&i8259_syscore_ops); + return domain; +} + +void __init init_i8259_irqs(void) +{ + __init_i8259_irqs(NULL); +} + +static void i8259_irq_dispatch(struct irq_desc *desc) +{ + struct irq_domain *domain = irq_desc_get_handler_data(desc); + int hwirq = i8259_poll(); + + if (hwirq < 0) + return; + + generic_handle_domain_irq(domain, hwirq); +} + +int __init i8259_of_init(struct device_node *node, struct device_node *parent) +{ + struct irq_domain *domain; + unsigned int parent_irq; + + domain = __init_i8259_irqs(node); + + parent_irq = irq_of_parse_and_map(node, 0); + if (!parent_irq) { + pr_err("Failed to map i8259 parent IRQ\n"); + irq_domain_remove(domain); + return -ENODEV; + } + + irq_set_chained_handler_and_data(parent_irq, i8259_irq_dispatch, + domain); + return 0; +} +IRQCHIP_DECLARE(i8259, "intel,i8259", i8259_of_init); |