Changes in kernel/generic/src/ddi/irq.c [431c402:ee50130] in mainline

File:

• kernel/generic/src/ddi/irq.c (modified) (17 diffs)

kernel/generic/src/ddi/irq.c

@@ -32 +32 @@
 /**
  * @file
- * @brief IRQ dispatcher
- *
- * This file provides means of connecting IRQs with respective device drivers
- * and logic for dispatching interrupts to IRQ handlers defined by those
- * drivers.
+ * @brief IRQ dispatcher.
+ *
+ * This file provides means of connecting IRQs with particular devices and logic
+ * for dispatching interrupts to IRQ handlers defined by those devices.
+ *
+ * This code is designed to support:
+ * - multiple devices sharing single IRQ
+ * - multiple IRQs per single device
+ * - multiple instances of the same device
+ *
+ *
+ * Note about architectures.
+ *
+ * Some architectures have the term IRQ well defined. Examples of such
+ * architectures include amd64, ia32 and mips32. Some other architectures, such
+ * as sparc64, don't use the term at all. In those cases, we boldly step forward
+ * and define what an IRQ is.
+ *
+ * The implementation is generic enough and still allows the architectures to
+ * use the hardware layout effectively.  For instance, on amd64 and ia32, where
+ * there is only 16 IRQs, the irq_hash_table can be optimized to a
+ * one-dimensional array. Next, when it is known that the IRQ numbers (aka
+ * INR's) are unique, the claim functions can always return IRQ_ACCEPT.
+ *
+ *
+ * Note about the irq_hash_table.
+ *
+ * The hash table is configured to use two keys: inr and devno.  However, the
+ * hash index is computed only from inr. Moreover, if devno is -1, the match is
+ * based on the return value of the claim() function instead of on devno.
  */
 
@@ -49 +74 @@
 #include <arch.h>
 
-slab_cache_t *irq_slab = NULL;
-
-/** Spinlock protecting the kernel IRQ hash table
+#define KEY_INR    0
+#define KEY_DEVNO  1
+
+/** Spinlock protecting the kernel IRQ hash table.
  *
  * This lock must be taken only when interrupts are disabled.
@@ -61 +87 @@
 static hash_table_t irq_kernel_hash_table;
 
-/** Spinlock protecting the uspace IRQ hash table
+/** Spinlock protecting the uspace IRQ hash table.
  *
  * This lock must be taken only when interrupts are disabled.
@@ -68 +94 @@
 IRQ_SPINLOCK_INITIALIZE(irq_uspace_hash_table_lock);
 
-/** The uspace IRQ hash table */
+/** The uspace IRQ hash table. */
 hash_table_t irq_uspace_hash_table;
 
+/**
+ * Hash table operations for cases when we know that there will be collisions
+ * between different keys.
+ */
 static size_t irq_ht_hash(sysarg_t *key);
 static bool irq_ht_compare(sysarg_t *key, size_t keys, link_t *item);
@@ -81 +111 @@
 };
 
-/** Number of buckets in either of the hash tables */
+/**
+ * Hash table operations for cases when we know that there will be no collisions
+ * between different keys.  However, there might be still collisions among
+ * elements with single key (sharing of one IRQ).
+ */
+static size_t irq_lin_hash(sysarg_t *key);
+static bool irq_lin_compare(sysarg_t *key, size_t keys, link_t *item);
+static void irq_lin_remove(link_t *item);
+
+static hash_table_operations_t irq_lin_ops = {
+        .hash = irq_lin_hash,
+        .compare = irq_lin_compare,
+        .remove_callback = irq_lin_remove,
+};
+
+/** Number of buckets in either of the hash tables. */
 static size_t buckets;
 
-/** Last valid INR */
+/** Last valid INR. */
 inr_t last_inr = 0;
 
-/** Initialize IRQ subsystem
- *
- * @param inrs    Numbers of unique IRQ numbers or INRs.
- * @param chains  Number of buckets in the hash table.
+/** Initialize IRQ subsystem.
+ *
+ * @param inrs   Numbers of unique IRQ numbers or INRs.
+ * @param chains Number of chains in the hash table.
  *
  */
@@ -98 +143 @@
         last_inr = inrs - 1;
 
-        irq_slab = slab_cache_create("irq_t", sizeof(irq_t), 0, NULL, NULL,
-            FRAME_ATOMIC);
-        assert(irq_slab);
-
-        hash_table_create(&irq_uspace_hash_table, chains, 2, &irq_ht_ops);
-        hash_table_create(&irq_kernel_hash_table, chains, 2, &irq_ht_ops);
-}
-
-/** Initialize one IRQ structure
- *
- * @param irq  Pointer to the IRQ structure to be initialized.
+        /*
+         * Be smart about the choice of the hash table operations.  In cases in
+         * which inrs equals the requested number of chains (i.e. where there is
+         * no collision between different keys), we can use optimized set of
+         * operations.
+         */
+        if (inrs == chains) {
+                hash_table_create(&irq_uspace_hash_table, chains, 2,
+                    &irq_lin_ops);
+                hash_table_create(&irq_kernel_hash_table, chains, 2,
+                    &irq_lin_ops);
+        } else {
+                hash_table_create(&irq_uspace_hash_table, chains, 2,
+                    &irq_ht_ops);
+                hash_table_create(&irq_kernel_hash_table, chains, 2,
+                    &irq_ht_ops);
+        }
+}
+
+/** Initialize one IRQ structure.
+ *
+ * @param irq Pointer to the IRQ structure to be initialized.
  *
  */
@@ -116 +172 @@
         link_initialize(&irq->link);
         irq_spinlock_initialize(&irq->lock, "irq.lock");
+        link_initialize(&irq->notif_cfg.link);
         irq->inr = -1;
+        irq->devno = -1;
         
         irq_initialize_arch(irq);
 }
 
-/** Register IRQ for device
+/** Register IRQ for device.
  *
  * The irq structure must be filled with information about the interrupt source
  * and with the claim() function pointer and handler() function pointer.
  *
- * @param irq  IRQ structure belonging to a device.
+ * @param irq IRQ structure belonging to a device.
  *
  */
@@ -132 +190 @@
 {
         sysarg_t key[] = {
-                [IRQ_HT_KEY_INR] = (sysarg_t) irq->inr,
-                [IRQ_HT_KEY_MODE] = (sysarg_t) IRQ_HT_MODE_NO_CLAIM 
+                (sysarg_t) irq->inr,
+                (sysarg_t) irq->devno
         };
         
@@ -143 +201 @@
 }
 
-/** Search and lock the uspace IRQ hash table */
+/** Search and lock the uspace IRQ hash table.
+ *
+ */
 static irq_t *irq_dispatch_and_lock_uspace(inr_t inr)
 {
         link_t *lnk;
         sysarg_t key[] = {
-                [IRQ_HT_KEY_INR] = (sysarg_t) inr,
-                [IRQ_HT_KEY_MODE] = (sysarg_t) IRQ_HT_MODE_CLAIM
+                (sysarg_t) inr,
+                (sysarg_t) -1    /* Search will use claim() instead of devno */
         };
         
@@ -164 +224 @@
 }
 
-/** Search and lock the kernel IRQ hash table */
+/** Search and lock the kernel IRQ hash table.
+ *
+ */
 static irq_t *irq_dispatch_and_lock_kernel(inr_t inr)
 {
         link_t *lnk;
         sysarg_t key[] = {
-                [IRQ_HT_KEY_INR] = (sysarg_t) inr,
-                [IRQ_HT_KEY_MODE] = (sysarg_t) IRQ_HT_MODE_CLAIM
+                (sysarg_t) inr,
+                (sysarg_t) -1    /* Search will use claim() instead of devno */
         };
         
@@ -185 +247 @@
 }
 
-/** Dispatch the IRQ
+/** Dispatch the IRQ.
  *
  * We assume this function is only called from interrupt context (i.e. that
@@ -193 +255 @@
  * return with interrupts disabled and holding the respective structure.
  *
- * @param inr  Interrupt number (aka inr or irq).
+ * @param inr Interrupt number (aka inr or irq).
  *
  * @return IRQ structure of the respective device
@@ -223 +285 @@
 }
 
-/** Compute hash index for the key
- *
- * @param key  The first of the keys is inr and the second is mode. Only inr is
- *             used to compute the hash.
+/** Compute hash index for the key.
+ *
+ * This function computes hash index into the IRQ hash table for which there can
+ * be collisions between different INRs.
+ *
+ * The devno is not used to compute the hash.
+ *
+ * @param key The first of the keys is inr and the second is devno or -1.
  *
  * @return Index into the hash table.
@@ -233 +299 @@
 size_t irq_ht_hash(sysarg_t key[])
 {
-        inr_t inr = (inr_t) key[IRQ_HT_KEY_INR];
+        inr_t inr = (inr_t) key[KEY_INR];
         return inr % buckets;
 }
 
-/** Compare hash table element with a key
- *
- * If mode is IRQ_HT_MODE_CLAIM, the result of the claim() function is used for
- * the match. Otherwise the key does not match.
+/** Compare hash table element with a key.
+ *
+ * There are two things to note about this function.  First, it is used for the
+ * more complex architecture setup in which there are way too many interrupt
+ * numbers (i.e. inr's) to arrange the hash table so that collisions occur only
+ * among same inrs of different devnos. So the explicit check for inr match must
+ * be done.  Second, if devno is -1, the second key (i.e. devno) is not used for
+ * the match and the result of the claim() function is used instead.
  *
  * This function assumes interrupts are already disabled.
  *
- * @param key   Keys (i.e. inr and mode).
- * @param keys  This is 2. 
- * @param item  The item to compare the key with.
- *
- * @return True on match
- * @return False on no match
+ * @param key  Keys (i.e. inr and devno).
+ * @param keys This is 2. 
+ * @param item The item to compare the key with.
+ *
+ * @return true on match
+ * @return false on no match
  *
  */
@@ -255 +325 @@
 {
         irq_t *irq = hash_table_get_instance(item, irq_t, link);
-        inr_t inr = (inr_t) key[IRQ_HT_KEY_INR];
-        irq_ht_mode_t mode = (irq_ht_mode_t) key[IRQ_HT_KEY_MODE];
+        inr_t inr = (inr_t) key[KEY_INR];
+        devno_t devno = (devno_t) key[KEY_DEVNO];
         
         bool rv;
         
         irq_spinlock_lock(&irq->lock, false);
-        if (mode == IRQ_HT_MODE_CLAIM) {
+        if (devno == -1) {
                 /* Invoked by irq_dispatch_and_lock(). */
-                rv = ((irq->inr == inr) && (irq->claim(irq) == IRQ_ACCEPT));
+                rv = ((irq->inr == inr) &&
+                    (irq->claim(irq) == IRQ_ACCEPT));
         } else {
                 /* Invoked by irq_find_and_lock(). */
-                rv = false;
+                rv = ((irq->inr == inr) && (irq->devno == devno));
         }
         
@@ -276 +347 @@
 }
 
-/** Unlock IRQ structure after hash_table_remove()
- *
- * @param lnk  Link in the removed and locked IRQ structure.
+/** Unlock IRQ structure after hash_table_remove().
+ *
+ * @param lnk Link in the removed and locked IRQ structure.
  */
 void irq_ht_remove(link_t *lnk)
@@ -287 +358 @@
 }
 
+/** Compute hash index for the key.
+ *
+ * This function computes hash index into the IRQ hash table for which there are
+ * no collisions between different INRs.
+ *
+ * @param key The first of the keys is inr and the second is devno or -1.
+ *
+ * @return Index into the hash table.
+ *
+ */
+size_t irq_lin_hash(sysarg_t key[])
+{
+        inr_t inr = (inr_t) key[KEY_INR];
+        return inr;
+}
+
+/** Compare hash table element with a key.
+ *
+ * There are two things to note about this function.  First, it is used for the
+ * less complex architecture setup in which there are not too many interrupt
+ * numbers (i.e. inr's) to arrange the hash table so that collisions occur only
+ * among same inrs of different devnos. So the explicit check for inr match is
+ * not done.  Second, if devno is -1, the second key (i.e. devno) is not used
+ * for the match and the result of the claim() function is used instead.
+ *
+ * This function assumes interrupts are already disabled.
+ *
+ * @param key  Keys (i.e. inr and devno).
+ * @param keys This is 2. 
+ * @param item The item to compare the key with.
+ *
+ * @return true on match
+ * @return false on no match
+ *
+ */
+bool irq_lin_compare(sysarg_t key[], size_t keys, link_t *item)
+{
+        irq_t *irq = list_get_instance(item, irq_t, link);
+        devno_t devno = (devno_t) key[KEY_DEVNO];
+        bool rv;
+        
+        irq_spinlock_lock(&irq->lock, false);
+        if (devno == -1) {
+                /* Invoked by irq_dispatch_and_lock() */
+                rv = (irq->claim(irq) == IRQ_ACCEPT);
+        } else {
+                /* Invoked by irq_find_and_lock() */
+                rv = (irq->devno == devno);
+        }
+        
+        /* unlock only on non-match */
+        if (!rv)
+                irq_spinlock_unlock(&irq->lock, false);
+        
+        return rv;
+}
+
+/** Unlock IRQ structure after hash_table_remove().
+ *
+ * @param lnk Link in the removed and locked IRQ structure.
+ *
+ */
+void irq_lin_remove(link_t *lnk)
+{
+        irq_t *irq __attribute__((unused))
+            = hash_table_get_instance(lnk, irq_t, link);
+        irq_spinlock_unlock(&irq->lock, false);
+}
+
 /** @}
  */