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Re: [Qemu-devel] [PATCH 2/6] [RFC] Emulation of GRLIB IRQMP as defined i


From: Fabien Chouteau
Subject: Re: [Qemu-devel] [PATCH 2/6] [RFC] Emulation of GRLIB IRQMP as defined in GRLIB IP Core User's Manual.
Date: Thu, 09 Dec 2010 12:32:03 +0100
User-agent: Mozilla/5.0 (X11; U; Linux i686; en-US; rv:1.9.2.12) Gecko/20101027 Thunderbird/3.1.6

On 12/09/2010 12:06 PM, Edgar E. Iglesias wrote:
On Thu, Dec 09, 2010 at 12:03:35PM +0100, Fabien Chouteau wrote:
On 12/09/2010 11:32 AM, Edgar E. Iglesias wrote:
On Mon, Dec 06, 2010 at 10:26:03AM +0100, Fabien Chouteau wrote:

Signed-off-by: Fabien Chouteau<address@hidden>
---
   hw/grlib_irqmp.c |  416 
++++++++++++++++++++++++++++++++++++++++++++++++++++++
   1 files changed, 416 insertions(+), 0 deletions(-)

diff --git a/hw/grlib_irqmp.c b/hw/grlib_irqmp.c
new file mode 100644
index 0000000..69e1553
--- /dev/null
+++ b/hw/grlib_irqmp.c
@@ -0,0 +1,416 @@
+/*
+ * QEMU GRLIB IRQMP Emulator
+ *
+ * (Multiprocessor and extended interrupt not supported)
+ *
+ * Copyright (c) 2010 AdaCore
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to 
deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
+ * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING 
FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+ * THE SOFTWARE.
+ */
+
+#include "sysbus.h"
+#include "cpu.h"
+
+#include "grlib.h"
+
+/* #define DEBUG_IRQ */
+
+#ifdef DEBUG_IRQ
+#define DPRINTF(fmt, ...)                                       \
+    do { printf("IRQMP: " fmt , ## __VA_ARGS__); } while (0)
+#else
+#define DPRINTF(fmt, ...)
+#endif
+
+#define IRQMP_MAX_CPU 16
+#define IRQMP_REG_SIZE 256      /* Size of memory mapped registers */
+
+/* Memory mapped register offsets */
+#define LEVEL_OFFSET     0x00
+#define PENDING_OFFSET   0x04
+#define FORCE0_OFFSET    0x08
+#define CLEAR_OFFSET     0x0C
+#define MP_STATUS_OFFSET 0x10
+#define BROADCAST_OFFSET 0x14
+#define MASK_OFFSET      0x40
+#define FORCE_OFFSET     0x80
+#define EXTENDED_OFFSET  0xC0
+
+typedef struct IRQMP
+{
+    SysBusDevice busdev;
+
+    CPUSPARCState *env;
+} IRQMP;
+
+typedef struct IRQMPState
+{
+    uint32_t level;
+    uint32_t pending;
+    uint32_t clear;
+    uint32_t broadcast;
+
+    uint32_t mask[IRQMP_MAX_CPU];
+    uint32_t force[IRQMP_MAX_CPU];
+    uint32_t extended[IRQMP_MAX_CPU];
+
+    IRQMP    *parent;
+} IRQMPState;
+
+IRQMPState grlib_irqmp_state;
+
+void grlib_irqmp_set_irq(void *opaque, int irq, int level);
+
+DeviceState *grlib_irqmp_create(target_phys_addr_t   base,
+                                CPUState            *env,
+                                qemu_irq           **cpu_irqs,
+                                uint32_t             nr_irqs)
+{
+    DeviceState *dev;
+
+    assert(cpu_irqs != NULL);
+
+    dev = qdev_create(NULL, "grlib,irqmp");
+    qdev_prop_set_ptr(dev, "cpustate", env);
+
+    if (qdev_init(dev)) {
+        return NULL;
+    }
+
+    sysbus_mmio_map(sysbus_from_qdev(dev), 0, base);
+
+    *cpu_irqs = qemu_allocate_irqs(grlib_irqmp_set_irq,
+&grlib_irqmp_state,
+                                   nr_irqs);
+
+    return dev;
+}
+
+static void grlib_irqmp_check_irqs(CPUState *env)
+{
+    uint32_t pend   = 0;
+    uint32_t level0 = 0;
+    uint32_t level1 = 0;
+
+    assert(env != NULL);
+
+    /* IRQ for CPU 0 (no SMP support) */
+    pend = (grlib_irqmp_state.pending | grlib_irqmp_state.force[0])
+&   grlib_irqmp_state.mask[0];
+
+
+    level0 = pend&   ~grlib_irqmp_state.level;
+    level1 = pend&    grlib_irqmp_state.level;
+
+    DPRINTF("pend:0x%04x force:0x%04x mask:0x%04x lvl1:0x%04x lvl0:0x%04x\n",
+            grlib_irqmp_state.pending, grlib_irqmp_state.force[0],
+            grlib_irqmp_state.mask[0], level1, level0);
+
+    /* Trigger level1 interrupt first and level0 if there is no level1 */
+    if (level1 != 0) {
+        env->pil_in = level1;
+    } else {
+        env->pil_in = level0;
+    }
+
+    if (env->pil_in&&   (env->interrupt_index == 0 ||
+                        (env->interrupt_index&   ~15) == TT_EXTINT)) {
+        unsigned int i;
+
+        for (i = 15; i>   0; i--) {
+            if (env->pil_in&   (1<<   i)) {
+                int old_interrupt = env->interrupt_index;
+
+                env->interrupt_index = TT_EXTINT | i;
+                if (old_interrupt != env->interrupt_index) {
+                    DPRINTF("Set CPU IRQ %d\n", i);
+                    cpu_interrupt(env, CPU_INTERRUPT_HARD);
+                }
+                break;
+            }
+        }
+    } else if (!env->pil_in&&   (env->interrupt_index&   ~15) == TT_EXTINT) {
+        DPRINTF("Reset CPU IRQ %d\n", env->interrupt_index&   15);
+        env->interrupt_index = 0;
+        cpu_reset_interrupt(env, CPU_INTERRUPT_HARD);
+    }
+}
+
+void grlib_irqmp_ack(CPUSPARCState *env, int intno)
+{
+    assert(env != NULL);
+
+    uint32_t mask;
+
+    intno&= 15;
+    mask = 1<<   intno;
+
+    DPRINTF("grlib_irqmp_ack %d\n", intno);
+
+    /* Clear registers */
+    grlib_irqmp_state.pending&= ~mask;
+    grlib_irqmp_state.force[0]&= ~mask; /* Only CPU 0 (No SMP support) */
+
+    grlib_irqmp_check_irqs(env);
+}
+
+void grlib_irqmp_set_irq(void *opaque, int irq, int level)
+{
+    IRQMPState *s = opaque;
+    int         i = 0;
+
+    assert(opaque != NULL);
+    assert(s->parent != NULL);
+
+    if (level) {
+        DPRINTF("Raise CPU IRQ %d\n", irq);
+
+        if (s->broadcast&   1<<   irq) {
+            /* Broadcasted IRQ */
+            for (i = 0; i<   IRQMP_MAX_CPU; i++) {
+                s->force[i] |= 1<<   irq;
+            }
+        } else {
+            s->pending |= 1<<   irq;
+        }
+        grlib_irqmp_check_irqs(s->parent->env);
+
+    } else {
+
+        DPRINTF("Lower CPU IRQ %d\n", irq);
+        if (s->broadcast&   1<<   irq) {
+            /* Broadcasted IRQ */
+            for (i = 0; i<   IRQMP_MAX_CPU; i++) {
+                s->force[i]&= ~(1<<   irq);
+            }
+        } else {
+            s->pending&= ~(1<<   irq);
+        }

If you use the edge triggered interrupt model in the devices, then you
shouldn't clear the pending bit here. A pulse from the device should
set it and it should only get cleared when the CPU acks it.

The model you've coded here indicates that the devices use a level
triggered approach. And the clearing of the pending bit in
grlib_irqmp_ack becomes meaningless...

OK, so I use qemu_irq_pulse and do nothing in grlib_irqmp_set_irq when
level == 0...

Right. But I'm still not convinced about the edge triggered nature of the
device irq signals.

One question to ask is:
What happens if you setup a timer without auto-reload and let an
interrupt hit. In the interrupt handler you dont restart the timer
and you don't clear the IP bit. You just return.

Will you get re-hit by the timer interrupt over and over?

No, just one time.

If yes, the device interrupt line is connected to the IP bit and
needs to be acked by writing a 1 to the config reg. You shouldn't
use qemu_irq_pulse.

If no, the device interrupt is signaled as a pulse

Let's go with the pulse ;)

--
Fabien Chouteau




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