diff options
Diffstat (limited to 'arch/alpha/kernel/irq_i8259.c')
| -rw-r--r-- | arch/alpha/kernel/irq_i8259.c | 183 |
1 files changed, 183 insertions, 0 deletions
diff --git a/arch/alpha/kernel/irq_i8259.c b/arch/alpha/kernel/irq_i8259.c new file mode 100644 index 00000000000..b188683b83f --- /dev/null +++ b/arch/alpha/kernel/irq_i8259.c @@ -0,0 +1,183 @@ +/* + * linux/arch/alpha/kernel/irq_i8259.c + * + * This is the 'legacy' 8259A Programmable Interrupt Controller, + * present in the majority of PC/AT boxes. + * + * Started hacking from linux-2.3.30pre6/arch/i386/kernel/i8259.c. + */ + +#include <linux/config.h> +#include <linux/init.h> +#include <linux/cache.h> +#include <linux/sched.h> +#include <linux/irq.h> +#include <linux/interrupt.h> + +#include <asm/io.h> + +#include "proto.h" +#include "irq_impl.h" + + +/* Note mask bit is true for DISABLED irqs. */ +static unsigned int cached_irq_mask = 0xffff; +static DEFINE_SPINLOCK(i8259_irq_lock); + +static inline void +i8259_update_irq_hw(unsigned int irq, unsigned long mask) +{ + int port = 0x21; + if (irq & 8) mask >>= 8; + if (irq & 8) port = 0xA1; + outb(mask, port); +} + +inline void +i8259a_enable_irq(unsigned int irq) +{ + spin_lock(&i8259_irq_lock); + i8259_update_irq_hw(irq, cached_irq_mask &= ~(1 << irq)); + spin_unlock(&i8259_irq_lock); +} + +static inline void +__i8259a_disable_irq(unsigned int irq) +{ + i8259_update_irq_hw(irq, cached_irq_mask |= 1 << irq); +} + +void +i8259a_disable_irq(unsigned int irq) +{ + spin_lock(&i8259_irq_lock); + __i8259a_disable_irq(irq); + spin_unlock(&i8259_irq_lock); +} + +void +i8259a_mask_and_ack_irq(unsigned int irq) +{ + spin_lock(&i8259_irq_lock); + __i8259a_disable_irq(irq); + + /* Ack the interrupt making it the lowest priority. */ + if (irq >= 8) { + outb(0xE0 | (irq - 8), 0xa0); /* ack the slave */ + irq = 2; + } + outb(0xE0 | irq, 0x20); /* ack the master */ + spin_unlock(&i8259_irq_lock); +} + +unsigned int +i8259a_startup_irq(unsigned int irq) +{ + i8259a_enable_irq(irq); + return 0; /* never anything pending */ +} + +void +i8259a_end_irq(unsigned int irq) +{ + if (!(irq_desc[irq].status & (IRQ_DISABLED|IRQ_INPROGRESS))) + i8259a_enable_irq(irq); +} + +struct hw_interrupt_type i8259a_irq_type = { + .typename = "XT-PIC", + .startup = i8259a_startup_irq, + .shutdown = i8259a_disable_irq, + .enable = i8259a_enable_irq, + .disable = i8259a_disable_irq, + .ack = i8259a_mask_and_ack_irq, + .end = i8259a_end_irq, +}; + +void __init +init_i8259a_irqs(void) +{ + static struct irqaction cascade = { + .handler = no_action, + .name = "cascade", + }; + + long i; + + outb(0xff, 0x21); /* mask all of 8259A-1 */ + outb(0xff, 0xA1); /* mask all of 8259A-2 */ + + for (i = 0; i < 16; i++) { + irq_desc[i].status = IRQ_DISABLED; + irq_desc[i].handler = &i8259a_irq_type; + } + + setup_irq(2, &cascade); +} + + +#if defined(CONFIG_ALPHA_GENERIC) +# define IACK_SC alpha_mv.iack_sc +#elif defined(CONFIG_ALPHA_APECS) +# define IACK_SC APECS_IACK_SC +#elif defined(CONFIG_ALPHA_LCA) +# define IACK_SC LCA_IACK_SC +#elif defined(CONFIG_ALPHA_CIA) +# define IACK_SC CIA_IACK_SC +#elif defined(CONFIG_ALPHA_PYXIS) +# define IACK_SC PYXIS_IACK_SC +#elif defined(CONFIG_ALPHA_TITAN) +# define IACK_SC TITAN_IACK_SC +#elif defined(CONFIG_ALPHA_TSUNAMI) +# define IACK_SC TSUNAMI_IACK_SC +#elif defined(CONFIG_ALPHA_IRONGATE) +# define IACK_SC IRONGATE_IACK_SC +#endif +/* Note that CONFIG_ALPHA_POLARIS is intentionally left out here, since + sys_rx164 wants to use isa_no_iack_sc_device_interrupt for some reason. */ + +#if defined(IACK_SC) +void +isa_device_interrupt(unsigned long vector, struct pt_regs *regs) +{ + /* + * Generate a PCI interrupt acknowledge cycle. The PIC will + * respond with the interrupt vector of the highest priority + * interrupt that is pending. The PALcode sets up the + * interrupts vectors such that irq level L generates vector L. + */ + int j = *(vuip) IACK_SC; + j &= 0xff; + handle_irq(j, regs); +} +#endif + +#if defined(CONFIG_ALPHA_GENERIC) || !defined(IACK_SC) +void +isa_no_iack_sc_device_interrupt(unsigned long vector, struct pt_regs *regs) +{ + unsigned long pic; + + /* + * It seems to me that the probability of two or more *device* + * interrupts occurring at almost exactly the same time is + * pretty low. So why pay the price of checking for + * additional interrupts here if the common case can be + * handled so much easier? + */ + /* + * The first read of gives you *all* interrupting lines. + * Therefore, read the mask register and and out those lines + * not enabled. Note that some documentation has 21 and a1 + * write only. This is not true. + */ + pic = inb(0x20) | (inb(0xA0) << 8); /* read isr */ + pic &= 0xFFFB; /* mask out cascade & hibits */ + + while (pic) { + int j = ffz(~pic); + pic &= pic - 1; + handle_irq(j, regs); + } +} +#endif |