// SPDX-License-Identifier: GPL-2.0-or-later
/*
* i8259 interrupt controller driver.
*/
#undef DEBUG
#include <linux/ioport.h>
#include <linux/interrupt.h>
#include <linux/irqdomain.h>
#include <linux/kernel.h>
#include <linux/delay.h>
#include <asm/io.h>
#include <asm/i8259.h>
static volatile void __iomem *pci_intack; /* RO, gives us the irq vector */
static unsigned char cached_8259[2] = { 0xff, 0xff };
#define cached_A1 (cached_8259[0])
#define cached_21 (cached_8259[1])
static DEFINE_RAW_SPINLOCK(i8259_lock);
static struct irq_domain *i8259_host;
/*
* Acknowledge the IRQ using either the PCI host bridge's interrupt
* acknowledge feature or poll. How i8259_init() is called determines
* which is called. It should be noted that polling is broken on some
* IBM and Motorola PReP boxes so we must use the int-ack feature on them.
*/
unsigned int i8259_irq(void)
{
int irq;
int lock = 0;
/* Either int-ack or poll for the IRQ */
if (pci_intack)
irq = readb(pci_intack);
else {
raw_spin_lock(&i8259_lock);
lock = 1;
/* Perform an interrupt acknowledge cycle on controller 1. */
outb(0x0C, 0x20); /* prepare for poll */
irq = inb(0x20) & 7;
if (irq == 2 ) {
/*
* Interrupt is cascaded so perform interrupt
* acknowledge on controller 2.
*/
outb(0x0C, 0xA0); /* prepare for poll */
irq = (inb(0xA0) & 7) + 8;
}
}
if (irq == 7) {
/*
* This may be a spurious interrupt.
*
* Read the interrupt status register (ISR). If the most
* significant bit is not set then there is no valid
* interrupt.
*/
if (!pci_intack)
outb(0x0B, 0x20); /* ISR register */
if(~inb(0x20) & 0x80)
irq = 0;
} else if (irq == 0xff)
irq = 0;
if (lock)
raw_spin_unlock(&i8259_lock);
return irq;
}
static void i8259_mask_and_ack_irq(struct irq_data *d)
{
unsigned long flags;
raw_spin_lock_irqsave(&i8259_lock, flags);
if (d->irq > 7) {
cached_A1 |= 1 << (d->irq-8);
inb(0xA1); /* DUMMY */
outb(cached_A1, 0xA1);
outb(0x20, 0xA0); /* Non-specific EOI */
outb(0x20, 0x20); /* Non-specific EOI to cascade */
} else {
cached_21 |= 1 << d->irq;
inb(0x21); /* DUMMY */
outb(cached_21, 0x21);
outb(0x20, 0x20); /* Non-specific EOI */
}
raw_spin_unlock_irqrestore(&i8259_lock, flags);
}
static void i8259_set_irq_mask(int irq_nr)
{
outb(cached_A1,0xA1);
outb(cached_21,0x21);
}
static void i8259_mask_irq(struct irq_data *d)
{
unsigned long flags;
pr_debug("i8259_mask_irq(%d)\n", d->irq);
raw_spin_lock_irqsave(&i8259_lock, flags);
if (d->irq < 8)
cached_21 |= 1 << d->irq;
else
cached_A1 |= 1 << (d->irq-8);
i8259_set_irq_mask(d->irq);
raw_spin_unlock_irqrestore(&i8259_lock, flags);
}
static void i8259_unmask_irq(struct irq_data *d)
{
unsigned long flags;
pr_debug("i8259_unmask_irq(%d)\n", d->irq);
raw_spin_lock_irqsave(&i8259_lock, flags);
if (d->irq < 8)
cached_21 &= ~(1 << d->irq);
else
cached_A1 &= ~(1 << (d->irq-8));
i8259_set_irq_mask(d->irq);
raw_spin_unlock_irqrestore(&i8259_lock, flags);
}
static struct irq_chip i8259_pic = {
.name = "i8259",
.irq_mask = i8259_mask_irq,
.irq_disable = i8259_mask_irq,
.irq_unmask = i8259_unmask_irq,
.irq_mask_ack = i8259_mask_and_ack_irq,
};
static struct resource pic1_iores = {
.name = "8259 (master)",
.start = 0x20,
.end = 0x21,
.flags = IORESOURCE_IO | IORESOURCE_BUSY,
};
static struct resource pic2_iores = {
.name = "8259 (slave)",
.start = 0xa0,
.end = 0xa1,
.flags = IORESOURCE_IO | IORESOURCE_BUSY,
};
static struct resource pic_edgectrl_iores = {
.name = "8259 edge control",
.start = 0x4d0,
.end = 0x4d1,
.flags = IORESOURCE_IO | IORESOURCE_BUSY,
};
static int i8259_host_match(struct irq_domain *h, struct device_node *node,
enum irq_domain_bus_token bus_token)
{
struct device_node *of_node = irq_domain_get_of_node(h);
return of_node == NULL || of_node == node;
}
static int i8259_host_map(struct irq_domain *h, unsigned int virq,
irq_hw_number_t hw)
{
pr_debug("i8259_host_map(%d, 0x%lx)\n", virq, hw);
/* We block the internal cascade */
if (hw == 2)
irq_set_status_flags(virq, IRQ_NOREQUEST);
/* We use the level handler only for now, we might want to
* be more cautious here but that works for now
*/
irq_set_status_flags(virq, IRQ_LEVEL);
irq_set_chip_and_handler(virq, &i8259_pic, handle_level_irq);
return 0;
}
static int i8259_host_xlate(struct irq_domain *h, struct device_node *ct,
const u32 *intspec, unsigned int intsize,
irq_hw_number_t *out_hwirq, unsigned int *out_flags)
{
static unsigned char map_isa_senses[4] = {
IRQ_TYPE_LEVEL_LOW,
IRQ_TYPE_LEVEL_HIGH,
IRQ_TYPE_EDGE_FALLING,
IRQ_TYPE_EDGE_RISING,
};
*out_hwirq = intspec[0];
if (intsize > 1 && intspec[1] < 4)
*out_flags = map_isa_senses[intspec[1]];
else
*out_flags = IRQ_TYPE_NONE;
return 0;
}
static const struct irq_domain_ops i8259_host_ops = {
.match = i8259_host_match,
.map = i8259_host_map,
.xlate = i8259_host_xlate,
};
struct irq_domain *__init i8259_get_host(void)
{
return i8259_host;
}
/**
* i8259_init - Initialize the legacy controller
* @node: device node of the legacy PIC (can be NULL, but then, it will match
* all interrupts, so beware)
* @intack_addr: PCI interrupt acknowledge (real) address which will return
* the active irq from the 8259
*/
void i8259_init(struct device_node *node, unsigned long intack_addr)
{
unsigned long flags;
/* initialize the controller */
raw_spin_lock_irqsave(&i8259_lock, flags);
/* Mask all first */
outb(0xff, 0xA1);
outb(0xff, 0x21);
/* init master interrupt controller */
outb(0x11, 0x20); /* Start init sequence */
outb(0x00, 0x21); /* Vector base */
outb(0x04, 0x21); /* edge triggered, Cascade (slave) on IRQ2 */
outb(0x01, 0x21); /* Select 8086 mode */
/* init slave interrupt controller */
outb(0x11, 0xA0); /* Start init sequence */
outb(0x08, 0xA1); /* Vector base */
outb(0x02, 0xA1); /* edge triggered, Cascade (slave) on IRQ2 */
outb(0x01, 0xA1); /* Select 8086 mode */
/* That thing is slow */
udelay(100);
/* always read ISR */
outb(0x0B, 0x20);
outb(0x0B, 0xA0);
/* Unmask the internal cascade */
cached_21 &= ~(1 << 2);
/* Set interrupt masks */
outb(cached_A1, 0xA1);
outb(cached_21, 0x21);
raw_spin_unlock_irqrestore(&i8259_lock, flags);
/* create a legacy host */
i8259_host = irq_domain_add_legacy(node, NR_IRQS_LEGACY, 0, 0,
&i8259_host_ops, NULL);
if (i8259_host == NULL) {
printk(KERN_ERR "i8259: failed to allocate irq host !\n");
return;
}
/* reserve our resources */
/* XXX should we continue doing that ? it seems to cause problems
* with further requesting of PCI IO resources for that range...
* need to look into it.
*/
request_resource(&ioport_resource, &pic1_iores);
request_resource(&ioport_resource, &pic2_iores);
request_resource(&ioport_resource, &pic_edgectrl_iores);
if (intack_addr != 0)
pci_intack = ioremap(intack_addr, 1);
printk(KERN_INFO "i8259 legacy interrupt controller initialized\n");
}
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