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Re: [PATCH v4 33/33] hw/nios2: Machine with a Vectored Interrupt Control


From: Mark Cave-Ayland
Subject: Re: [PATCH v4 33/33] hw/nios2: Machine with a Vectored Interrupt Controller
Date: Tue, 8 Mar 2022 08:43:09 +0000
User-agent: Mozilla/5.0 (X11; Linux x86_64; rv:91.0) Gecko/20100101 Thunderbird/91.6.1

On 08/03/2022 07:20, Richard Henderson wrote:

From: Amir Gonnen <amir.gonnen@neuroblade.ai>

Demonstrate how to use nios2 VIC on a machine.
Introduce a new machine property to attach a VIC.

When VIC is present, let the CPU know that it should use the
External Interrupt Interface instead of the Internal Interrupt Interface.
The devices on the machine are attached to the VIC and not directly to cpu.
To allow VIC update EIC fields, we set the "cpu" property of the VIC
with a reference to the nios2 cpu.

Signed-off-by: Amir Gonnen <amir.gonnen@neuroblade.ai>
Message-Id: <20220303153906.2024748-6-amir.gonnen@neuroblade.ai>
[rth: Put a property on the 10m50-ghrd machine, rather than
       create a new machine class.]
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
---
  hw/nios2/10m50_devboard.c | 61 +++++++++++++++++++++++++++++++++------
  hw/nios2/Kconfig          |  1 +
  2 files changed, 53 insertions(+), 9 deletions(-)

diff --git a/hw/nios2/10m50_devboard.c b/hw/nios2/10m50_devboard.c
index f4931b8a67..bdbc6539c9 100644
--- a/hw/nios2/10m50_devboard.c
+++ b/hw/nios2/10m50_devboard.c
@@ -43,6 +43,8 @@ struct Nios2MachineState {
      MemoryRegion phys_tcm_alias;
      MemoryRegion phys_ram;
      MemoryRegion phys_ram_alias;
+
+    bool vic;
  };
#define TYPE_NIOS2_MACHINE MACHINE_TYPE_NAME("10m50-ghrd")
@@ -81,10 +83,40 @@ static void nios2_10m50_ghrd_init(MachineState *machine)
      memory_region_add_subregion(address_space_mem, 0xc0000000 + ram_base,
                                  &nms->phys_ram_alias);
- /* Create CPU -- FIXME */
-    cpu = NIOS2_CPU(cpu_create(TYPE_NIOS2_CPU));
-    for (i = 0; i < 32; i++) {
-        irq[i] = qdev_get_gpio_in_named(DEVICE(cpu), "IRQ", i);
+    /* Create CPU.  We need to set eic_present between init and realize. */
+    cpu = NIOS2_CPU(object_new(TYPE_NIOS2_CPU));
+
+    /* Enable the External Interrupt Controller within the CPU. */
+    cpu->eic_present = nms->vic;
+
+    /* Configure new exception vectors. */
+    cpu->reset_addr = 0xd4000000;
+    cpu->exception_addr = 0xc8000120;
+    cpu->fast_tlb_miss_addr = 0xc0000100;
+
+    qdev_realize(DEVICE(cpu), NULL, &error_fatal);
+    object_unref(CPU(cpu));

I believe this can be replaced with qdev_realize_and_unref()?

+    if (nms->vic) {
+        DeviceState *dev = qdev_new("nios2-vic");

And with a separate header for nios2_vic.h you can include that and use TYPE_NIOS2_VIC here instead of hard-coding the type name.

+        MemoryRegion *dev_mr;
+        qemu_irq cpu_irq;
+
+        object_property_set_link(OBJECT(dev), "cpu", OBJECT(cpu), 
&error_fatal);
+        sysbus_realize_and_unref(SYS_BUS_DEVICE(dev), &error_fatal);
+
+        cpu_irq = qdev_get_gpio_in_named(DEVICE(cpu), "EIC", 0);
+        sysbus_connect_irq(SYS_BUS_DEVICE(dev), 0, cpu_irq);
+        for (int i = 0; i < 32; i++) {
+            irq[i] = qdev_get_gpio_in(dev, i);
+        }
+
+        dev_mr = sysbus_mmio_get_region(SYS_BUS_DEVICE(dev), 0);
+        memory_region_add_subregion(address_space_mem, 0x18002000, dev_mr);
+    } else {
+        for (i = 0; i < 32; i++) {
+            irq[i] = qdev_get_gpio_in_named(DEVICE(cpu), "IRQ", i);
+        }
      }
/* Register: Altera 16550 UART */
@@ -105,15 +137,22 @@ static void nios2_10m50_ghrd_init(MachineState *machine)
      sysbus_mmio_map(SYS_BUS_DEVICE(dev), 0, 0xe0000880);
      sysbus_connect_irq(SYS_BUS_DEVICE(dev), 0, irq[5]);
- /* Configure new exception vectors and reset CPU for it to take effect. */
-    cpu->reset_addr = 0xd4000000;
-    cpu->exception_addr = 0xc8000120;
-    cpu->fast_tlb_miss_addr = 0xc0000100;
-
      nios2_load_kernel(cpu, ram_base, ram_size, 
nms->parent_obj.initrd_filename,
                        BINARY_DEVICE_TREE_FILE, NULL);
  }
+static bool get_vic(Object *obj, Error **errp)
+{
+    Nios2MachineState *nms = NIOS2_MACHINE(obj);
+    return nms->vic;
+}
+
+static void set_vic(Object *obj, bool value, Error **errp)
+{
+    Nios2MachineState *nms = NIOS2_MACHINE(obj);
+    nms->vic = value;
+}
+
  static void nios2_10m50_ghrd_class_init(ObjectClass *oc, void *data)
  {
      MachineClass *mc = MACHINE_CLASS(oc);
@@ -121,6 +160,10 @@ static void nios2_10m50_ghrd_class_init(ObjectClass *oc, 
void *data)
      mc->desc = "Altera 10M50 GHRD Nios II design";
      mc->init = nios2_10m50_ghrd_init;
      mc->is_default = true;
+
+    object_class_property_add_bool(oc, "vic", get_vic, set_vic);
+    object_class_property_set_description(oc, "vic",
+        "Set on/off to enable/disable the Vectored Interrupt Controller");
  }
static const TypeInfo nios2_10m50_ghrd_type_info = {
diff --git a/hw/nios2/Kconfig b/hw/nios2/Kconfig
index b10ea640da..4748ae27b6 100644
--- a/hw/nios2/Kconfig
+++ b/hw/nios2/Kconfig
@@ -3,6 +3,7 @@ config NIOS2_10M50
      select NIOS2
      select SERIAL
      select ALTERA_TIMER
+    select NIOS2_VIC
config NIOS2_GENERIC_NOMMU
      bool


ATB,

Mark.



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