1 files changed, 144 insertions, 100 deletions

diff --git a/libmaple/exti.c b/libmaple/exti.c
index e8ad52a..7f56712 100644
--- a/libmaple/exti.c
+++ b/libmaple/exti.c
@@ -23,19 +23,29 @@
  *****************************************************************************/
 
 /**
+ * @file exti.c
  * @brief External interrupt control routines
  */
 
 #include "libmaple.h"
 #include "exti.h"
 #include "nvic.h"
+#include "bitband.h"
 
-typedef struct ExtIChannel {
+/*
+ * Internal state
+ */
+
+/* Status bitmaps, for external interrupts with multiplexed IRQs */
+static uint16 exti_9_5_en = 0;
+static uint16 exti_15_10_en = 0;
+
+typedef struct exti_channel {
     void (*handler)(void);
     uint32 irq_line;
-} ExtIChannel;
+} exti_channel;
 
-static ExtIChannel exti_channels[] = {
+static exti_channel exti_channels[] = {
     { .handler = NULL, .irq_line = NVIC_EXTI0     },  // EXTI0
     { .handler = NULL, .irq_line = NVIC_EXTI1     },  // EXTI1
     { .handler = NULL, .irq_line = NVIC_EXTI2     },  // EXTI2
@@ -54,63 +64,127 @@ static ExtIChannel exti_channels[] = {
     { .handler = NULL, .irq_line = NVIC_EXTI15_10 },  // EXTI15
 };
 
-static inline void clear_pending(int bit) {
-    __set_bits(EXTI_PR, BIT(bit));
-    /* If the pending bit is cleared as the last instruction in an ISR,
-     * it won't actually be cleared in time and the ISR will fire again.
-     * Insert a 2-cycle buffer to allow it to take effect. */
-    asm volatile("nop");
-    asm volatile("nop");
-}
+/*
+ * Convenience routines
+ */
+
+static inline void enable_irq(afio_exti_num exti_num);
+static inline void maybe_disable_irq(afio_exti_num exti_num);
+
+/**
+ * @brief Register a handler to run upon external interrupt.
+ *
+ * This function assumes that the interrupt request corresponding to
+ * the given external interrupt is masked.
+ *
+ * @param num     External interrupt line number.
+ * @param port    Port to use as source input for external interrupt.
+ * @param handler Function handler to execute when interrupt is triggered.
+ * @param mode    Type of transition to trigger on, one of:
+ *                EXTI_RISING, EXTI_FALLING, EXTI_RISING_FALLING.
+ * @see exti_num
+ * @see exti_port
+ * @see exti_trigger_mode
+ */
+void exti_attach_interrupt(afio_exti_num num,
+                           afio_exti_port port,
+                           voidFuncPtr handler,
+                           exti_trigger_mode mode) {
+    ASSERT(handler);
 
-static inline void dispatch_handler(uint32 channel) {
-    ASSERT(exti_channels[channel].handler);
-    if (exti_channels[channel].handler) {
-        (exti_channels[channel].handler)();
+    /* Register the handler */
+    exti_channels[num].handler = handler;
+
+    /* Set trigger mode */
+    switch (mode) {
+    case EXTI_RISING:
+        *bb_perip(&EXTI_BASE->RTSR, num) = 1;
+        break;
+    case EXTI_FALLING:
+        *bb_perip(&EXTI_BASE->FTSR, num) = 1;
+        break;
+    case EXTI_RISING_FALLING:
+        *bb_perip(&EXTI_BASE->RTSR, num) = 1;
+        *bb_perip(&EXTI_BASE->FTSR, num) = 1;
+        break;
     }
+
+    /* Map num to port */
+    afio_exti_select(num, port);
+
+    /* Unmask external interrupt request */
+    *bb_perip(&EXTI_BASE->IMR, num) = 1;
+
+    /* Enable the interrupt line */
+    enable_irq(num);
+}
+
+/**
+ * @brief Unregister an external interrupt handler
+ * @param num Number of the external interrupt line to disable.
+ * @see exti_num
+ */
+void exti_detach_interrupt(afio_exti_num num) {
+    /* First, mask the interrupt request */
+    *bb_perip(&EXTI_BASE->IMR, num) = 0;
+
+    /* Then, clear the trigger selection registers */
+    *bb_perip(&EXTI_BASE->FTSR, num) = 0;
+    *bb_perip(&EXTI_BASE->RTSR, num) = 0;
+
+    /* Next, disable the IRQ, unless it's multiplexed and there are
+     * other active external interrupts on the same IRQ line */
+    maybe_disable_irq(num);
+
+    /* Finally, unregister the user's handler */
+    exti_channels[num].handler = NULL;
 }
 
-/* For EXTI0 through EXTI4, only one handler
- * is associated with each channel, so we
- * don't have to keep track of which channel
+/*
+ * Interrupt handlers
+ */
+
+static inline void clear_pending(uint32 exti_num);
+static inline void dispatch_handler(uint32 exti_num);
+
+/* For AFIO_EXTI_0 through AFIO_EXTI_4, only one handler is associated
+ * with each channel, so we don't have to keep track of which channel
  * we came from */
 void __irq_exti0(void) {
-    dispatch_handler(EXTI0);
-    clear_pending(EXTI0);
+    dispatch_handler(AFIO_EXTI_0);
+    clear_pending(AFIO_EXTI_0);
 }
 
 void __irq_exti1(void) {
-    dispatch_handler(EXTI1);
-    clear_pending(EXTI1);
+    dispatch_handler(AFIO_EXTI_1);
+    clear_pending(AFIO_EXTI_1);
 }
 
 void __irq_exti2(void) {
-    dispatch_handler(EXTI2);
-    clear_pending(EXTI2);
+    dispatch_handler(AFIO_EXTI_2);
+    clear_pending(AFIO_EXTI_2);
 }
 
 void __irq_exti3(void) {
-    dispatch_handler(EXTI3);
-    clear_pending(EXTI3);
+    dispatch_handler(AFIO_EXTI_3);
+    clear_pending(AFIO_EXTI_3);
 }
 
 void __irq_exti4(void) {
-    dispatch_handler(EXTI4);
-    clear_pending(EXTI4);
+    dispatch_handler(AFIO_EXTI_4);
+    clear_pending(AFIO_EXTI_4);
 }
 
 void __irq_exti9_5(void) {
     /* Figure out which channel it came from  */
-    uint32 pending;
+    uint32 pending = GET_BITS(EXTI_BASE->PR, 5, 9);
     uint32 i;
-    pending = REG_GET(EXTI_PR);
-    pending = GET_BITS(pending, 5, 9);
 
     /* Dispatch every handler if the pending bit is set */
     for (i = 0; i < 5; i++) {
         if (pending & 0x1) {
-            dispatch_handler(EXTI5 + i);
-            clear_pending(EXTI5 + i);
+            dispatch_handler(AFIO_EXTI_5 + i);
+            clear_pending(AFIO_EXTI_5 + i);
         }
         pending >>= 1;
     }
@@ -118,89 +192,59 @@ void __irq_exti9_5(void) {
 
 void __irq_exti15_10(void) {
     /* Figure out which channel it came from  */
-    uint32 pending;
+    uint32 pending = GET_BITS(EXTI_BASE->PR, 10, 15);
     uint32 i;
-    pending = REG_GET(EXTI_PR);
-    pending = GET_BITS(pending, 10, 15);
 
     /* Dispatch every handler if the pending bit is set */
     for (i = 0; i < 6; i++) {
         if (pending & 0x1) {
-            dispatch_handler(EXTI10 + i);
-            clear_pending(EXTI10 + i);
+            dispatch_handler(AFIO_EXTI_10 + i);
+            clear_pending(AFIO_EXTI_10 + i);
         }
         pending >>= 1;
     }
 }
 
-
-/**
- * @brief Register a handler to run upon external interrupt
- * @param port source port of pin (eg EXTI_CONFIG_PORTA)
- * @param pin pin number on the source port
- * @param handler function handler to execute
- * @param mode type of transition to trigger on
+/*
+ * Auxiliary functions
  */
-void exti_attach_interrupt(uint32 port,
-                           uint32 pin,
-                           voidFuncPtr handler,
-                           uint32 mode) {
-    static uint32 afio_regs[] = {
-        AFIO_EXTICR1,         // EXT0-3
-        AFIO_EXTICR2,         // EXT4-7
-        AFIO_EXTICR3,         // EXT8-11
-        AFIO_EXTICR4,         // EXT12-15
-    };
-
-    /* Note: All of the following code assumes that EXTI0 = 0  */
-    ASSERT(EXTI0 == 0);
-    ASSERT(handler);
-
-    uint32 channel = pin;
 
-    /* map port to channel */
-    __write(afio_regs[pin/4], (port << ((pin % 4) * 4)));
-
-    /* Unmask appropriate interrupt line  */
-    __set_bits(EXTI_IMR, BIT(channel));
-
-    /* Set trigger mode  */
-    switch (mode) {
-    case EXTI_RISING:
-        __set_bits(EXTI_RTSR, BIT(channel));
-        break;
-
-    case EXTI_FALLING:
-        __set_bits(EXTI_FTSR, BIT(channel));
-        break;
+static inline void clear_pending(uint32 exti_num) {
+    *bb_perip(&EXTI_BASE->PR, exti_num) = 1;
+    /* If the pending bit is cleared as the last instruction in an ISR,
+     * it won't actually be cleared in time and the ISR will fire again.
+     * Insert a 2-cycle buffer to allow it to take effect. */
+    asm volatile("nop");
+    asm volatile("nop");
+}
 
-    case EXTI_RISING_FALLING:
-        __set_bits(EXTI_RTSR, BIT(channel));
-        __set_bits(EXTI_FTSR, BIT(channel));
-        break;
+static inline void dispatch_handler(uint32 exti_num) {
+    ASSERT(exti_channels[exti_num].handler);
+    if (exti_channels[exti_num].handler) {
+        (exti_channels[exti_num].handler)();
     }
-
-    /* Register the handler  */
-    exti_channels[channel].handler = handler;
-
-    /* Configure the enable interrupt bits for the NVIC  */
-    nvic_irq_enable(exti_channels[channel].irq_line);
 }
 
+static inline void enable_irq(afio_exti_num exti) {
+    /* Maybe twiddle the IRQ bitmap for extis with multiplexed IRQs */
+    if (exti > 4) {
+        uint16 *bitmap = exti < 10 ? &exti_9_5_en : &exti_15_10_en;
+        *bb_sramp(bitmap, exti) = 1;
+    }
 
-/**
- * @brief Unregister an external interrupt handler
- * @param channel channel to disable (eg EXTI0)
- */
-void exti_detach_interrupt(uint32 channel) {
-    ASSERT(channel < NR_EXTI_CHANNELS);
-    ASSERT(EXTI0 == 0);
-
-    __clear_bits(EXTI_IMR,  BIT(channel));
-    __clear_bits(EXTI_FTSR, BIT(channel));
-    __clear_bits(EXTI_RTSR, BIT(channel));
-
-    nvic_irq_disable(exti_channels[channel].irq_line);
+    nvic_irq_enable(exti_channels[exti].irq_line);
+}
 
-    exti_channels[channel].handler = NULL;
+static inline void maybe_disable_irq(afio_exti_num exti) {
+    if (exti > 4) {
+        uint16 *bitmap = exti < 10 ? &exti_9_5_en : &exti_15_10_en;
+        *bb_sramp(bitmap, exti) = 0;
+        if (*bitmap == 0) {
+            /* All of the external interrupts which share this IRQ
+             * line are disabled. */
+            nvic_irq_disable(exti_channels[exti].irq_line);
+        }
+    } else {
+        nvic_irq_disable(exti_channels[exti].irq_line);
+    }
 }