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29 * Copyright 2007 Develer S.r.l. (http://www.develer.com/)
35 * \author Francesco Sacchi <batt@develer.com>
37 * \brief System IRQ handler for Atmel AT91 ARM7 processors.
39 * In Atmel AT91 ARM7TDMI processors, there are various
40 * peripheral interrupt sources.
41 * In general, every source has its own interrupt vector, so it
42 * is possible to assign a specific handler for each interrupt
44 * However, there are a few sources called "system sources" that
45 * share a common IRQ line and vector, called "system IRQ".
46 * So a unique system IRQ dispatcher is implemented here.
47 * This module also contains an interface to manage every source
48 * independently. It is possible to assign to every system IRQ
49 * a specific IRQ handler.
51 * \see sysirq_setHandler
52 * \see sysirq_setEnable
55 #include "sysirq_at91.h"
56 #include <io/at91sam7s.h>
58 #include <cfg/module.h>
59 #include <cfg/macros.h>
62 * Enable/disable the Periodic Interrupt Timer
65 INLINE void pit_setEnable(bool enable)
70 PIT_MR &= ~BV(PITIEN);
74 * Table containing all system irqs.
76 static SysIrq sysirq_tab[] =
78 /* PIT, Periodic Interval Timer (System timer)*/
81 .setEnable = pit_setEnable,
84 /* TODO: add other system sources here */
87 STATIC_ASSERT(countof(sysirq_tab) == SYSIRQ_CNT);
90 * \brief Interrupt entry.
93 asm volatile("sub lr, lr,#4" "\n\t" /* Adjust LR */ \
94 "stmfd sp!,{r0-r12,lr}" "\n\t" /* Save registers on IRQ stack. */ \
95 "mrs r1, spsr" "\n\t" /* Save SPSR */ \
96 "stmfd sp!,{r1}" "\n\t") /* */
99 * \brief Interrupt exit.
102 asm volatile("ldmfd sp!, {r1}" "\n\t" /* Restore SPSR */ \
103 "msr spsr_c, r1" "\n\t" /* */ \
104 "ldr r0, =0xFFFFF000" "\n\t" /* End of interrupt. */ \
105 "str r0, [r0, #0x130]" "\n\t" /* */ \
106 "ldmfd sp!, {r0-r12, pc}^" "\n\t") /* Restore registers and return. */
110 * System IRQ dispatcher.
111 * This is the entry point for all system IRQs in AT91.
112 * This function checks for interrupt enable state of
113 * various sources (system timer, etc..) and calls
114 * the corresponding handler.
116 static void sysirq_dispatcher(void) __attribute__ ((naked));
117 static void sysirq_dispatcher(void)
120 for (unsigned i = 0; i < countof(sysirq_tab); i++)
122 if (sysirq_tab[i].enabled
123 && sysirq_tab[i].handler)
124 sysirq_tab[i].handler();
130 #define SYSIRQ_PRIORITY 0 ///< default priority for system irqs.
136 * Init system IRQ handling.
137 * \note all system interrupts are disabled.
139 void sysirq_init(void)
142 IRQ_SAVE_DISABLE(flags);
144 /* Disable all system interrupts */
145 for (unsigned i = 0; i < countof(sysirq_tab); i++)
146 sysirq_tab[i].setEnable(false);
148 /* Set the vector. */
149 AIC_SVR(SYSC_ID) = sysirq_dispatcher;
150 /* Initialize to edge triggered with defined priority. */
151 AIC_SMR(SYSC_ID) = AIC_SRCTYPE_INT_EDGE_TRIGGERED | SYSIRQ_PRIORITY;
152 /* Clear pending interrupt */
153 AIC_ICCR = BV(SYSC_ID);
154 /* Enable the system IRQ */
155 AIC_IECR = BV(SYSC_ID);
163 * Helper function used to set handler for system IRQ \a irq.
165 void sysirq_setHandler(sysirq_t irq, sysirq_handler_t handler)
168 ASSERT(irq < SYSIRQ_CNT);
169 sysirq_tab[irq].handler = handler;
173 * Helper function used to enable/disable system IRQ \a irq.
175 void sysirq_setEnable(sysirq_t irq, bool enable)
178 ASSERT(irq < SYSIRQ_CNT);
180 sysirq_tab[irq].setEnable(enable);
181 sysirq_tab[irq].enabled = enable;
185 * Helper function used to get system IRQ \a irq state.
187 bool sysirq_enabled(sysirq_t irq)
190 ASSERT(irq < SYSIRQ_CNT);
192 return sysirq_tab[irq].enabled;