hw/arm: make bitbanded IO optional on ARMv7-M

Some ARM CPUs have bitbanded IO, a memory region that allows convenient
bit access via 32-bit memory loads/stores.  This eliminates the need for
read-modify-update instruction sequences.

This patch makes this optional feature an ARMv7MState qdev property,
allowing boards to choose whether they want bitbanding or not.

Status of boards:
 * iotkit (Cortex M33), no bitband
 * mps2 (Cortex M3), bitband
 * msf2 (Cortex M3), bitband
 * stellaris (Cortex M3), bitband
 * stm32f205 (Cortex M3), bitband

As a side-effect of this patch, Peter Maydell noted that the Ethernet
controller on mps2 board is now accessible.  Previously they were hidden
by the bitband region (which does not exist on the real board).

Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Reviewed-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
Message-id: 20180814162739.11814-2-stefanha@redhat.com
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>

diff --git a/hw/arm/armv7m.c b/hw/arm/armv7m.c
index 6b0766605745f3874c023dbb895d8784978ab08b..878613994d238a2ea5be22d41c81190517c48211 100644 (file)
--- a/hw/arm/armv7m.c
+++ b/hw/arm/armv7m.c
@@ -211,25 +211,27 @@ static void armv7m_realize(DeviceState *dev, Error **errp)
     memory_region_add_subregion(&s->container, 0xe000e000,
                                 sysbus_mmio_get_region(sbd, 0));
 
-    for (i = 0; i < ARRAY_SIZE(s->bitband); i++) {
-        Object *obj = OBJECT(&s->bitband[i]);
-        SysBusDevice *sbd = SYS_BUS_DEVICE(&s->bitband[i]);
-
-        object_property_set_int(obj, bitband_input_addr[i], "base", &err);
-        if (err != NULL) {
-            error_propagate(errp, err);
-            return;
+    if (s->enable_bitband) {
+        for (i = 0; i < ARRAY_SIZE(s->bitband); i++) {
+            Object *obj = OBJECT(&s->bitband[i]);
+            SysBusDevice *sbd = SYS_BUS_DEVICE(&s->bitband[i]);
+
+            object_property_set_int(obj, bitband_input_addr[i], "base", &err);
+            if (err != NULL) {
+                error_propagate(errp, err);
+                return;
+            }
+            object_property_set_link(obj, OBJECT(s->board_memory),
+                                     "source-memory", &error_abort);
+            object_property_set_bool(obj, true, "realized", &err);
+            if (err != NULL) {
+                error_propagate(errp, err);
+                return;
+            }
+
+            memory_region_add_subregion(&s->container, bitband_output_addr[i],
+                                        sysbus_mmio_get_region(sbd, 0));
         }
-        object_property_set_link(obj, OBJECT(s->board_memory),
-                                 "source-memory", &error_abort);
-        object_property_set_bool(obj, true, "realized", &err);
-        if (err != NULL) {
-            error_propagate(errp, err);
-            return;
-        }
-
-        memory_region_add_subregion(&s->container, bitband_output_addr[i],
-                                    sysbus_mmio_get_region(sbd, 0));
     }
 }
 
@@ -239,6 +241,7 @@ static Property armv7m_properties[] = {
                      MemoryRegion *),
     DEFINE_PROP_LINK("idau", ARMv7MState, idau, TYPE_IDAU_INTERFACE, Object *),
     DEFINE_PROP_UINT32("init-svtor", ARMv7MState, init_svtor, 0),
+    DEFINE_PROP_BOOL("enable-bitband", ARMv7MState, enable_bitband, false),
     DEFINE_PROP_END_OF_LIST(),
 };
 

diff --git a/hw/arm/mps2.c b/hw/arm/mps2.c
index c3946da31730e6320cef3d7de273fce3bcce8944..0a0ae867d9bffe7650e2a852d58d150b10ca774e 100644 (file)
--- a/hw/arm/mps2.c
+++ b/hw/arm/mps2.c
@@ -186,6 +186,7 @@ static void mps2_common_init(MachineState *machine)
         g_assert_not_reached();
     }
     qdev_prop_set_string(armv7m, "cpu-type", machine->cpu_type);
+    qdev_prop_set_bit(armv7m, "enable-bitband", true);
     object_property_set_link(OBJECT(&mms->armv7m), OBJECT(system_memory),
                              "memory", &error_abort);
     object_property_set_bool(OBJECT(&mms->armv7m), true, "realized",

diff --git a/hw/arm/msf2-soc.c b/hw/arm/msf2-soc.c
index dbefade644d05d491ab30dab48300203870d9dfe..2702e90b453e5b262a505fe381ead63f63dbc01b 100644 (file)
--- a/hw/arm/msf2-soc.c
+++ b/hw/arm/msf2-soc.c
@@ -117,6 +117,7 @@ static void m2sxxx_soc_realize(DeviceState *dev_soc, Error **errp)
     armv7m = DEVICE(&s->armv7m);
     qdev_prop_set_uint32(armv7m, "num-irq", 81);
     qdev_prop_set_string(armv7m, "cpu-type", s->cpu_type);
+    qdev_prop_set_bit(armv7m, "enable-bitband", true);
     object_property_set_link(OBJECT(&s->armv7m), OBJECT(get_system_memory()),
                                      "memory", &error_abort);
     object_property_set_bool(OBJECT(&s->armv7m), true, "realized", &err);

diff --git a/hw/arm/stellaris.c b/hw/arm/stellaris.c
index dc521b4a5a8a8881c4c4b149cf6dcf2e89950bcd..6c69ce79b20d2b1b7f5b236da44bd29167f6df81 100644 (file)
--- a/hw/arm/stellaris.c
+++ b/hw/arm/stellaris.c
@@ -1304,6 +1304,7 @@ static void stellaris_init(MachineState *ms, stellaris_board_info *board)
     nvic = qdev_create(NULL, TYPE_ARMV7M);
     qdev_prop_set_uint32(nvic, "num-irq", NUM_IRQ_LINES);
     qdev_prop_set_string(nvic, "cpu-type", ms->cpu_type);
+    qdev_prop_set_bit(nvic, "enable-bitband", true);
     object_property_set_link(OBJECT(nvic), OBJECT(get_system_memory()),
                                      "memory", &error_abort);
     /* This will exit with an error if the user passed us a bad cpu_type */

diff --git a/hw/arm/stm32f205_soc.c b/hw/arm/stm32f205_soc.c
index c486d06a8b0994dfbc1011eb8d952d9bab122612..980e5af13c599d22eb689b68959e6f31c0b4eb4f 100644 (file)
--- a/hw/arm/stm32f205_soc.c
+++ b/hw/arm/stm32f205_soc.c
@@ -109,6 +109,7 @@ static void stm32f205_soc_realize(DeviceState *dev_soc, Error **errp)
     armv7m = DEVICE(&s->armv7m);
     qdev_prop_set_uint32(armv7m, "num-irq", 96);
     qdev_prop_set_string(armv7m, "cpu-type", s->cpu_type);
+    qdev_prop_set_bit(armv7m, "enable-bitband", true);
     object_property_set_link(OBJECT(&s->armv7m), OBJECT(get_system_memory()),
                                      "memory", &error_abort);
     object_property_set_bool(OBJECT(&s->armv7m), true, "realized", &err);

diff --git a/include/hw/arm/armv7m.h b/include/hw/arm/armv7m.h
index 78308d148460d4553aa2cab6be783b88452a29e6..2ba24953b633185da610efeba4beefc541ac38d4 100644 (file)
--- a/include/hw/arm/armv7m.h
+++ b/include/hw/arm/armv7m.h
@@ -43,6 +43,7 @@ typedef struct {
  *   devices will be automatically layered on top of this view.)
  * + Property "idau": IDAU interface (forwarded to CPU object)
  * + Property "init-svtor": secure VTOR reset value (forwarded to CPU object)
+ * + Property "enable-bitband": expose bitbanded IO
  */
 typedef struct ARMv7MState {
     /*< private >*/
@@ -63,6 +64,7 @@ typedef struct ARMv7MState {
     MemoryRegion *board_memory;
     Object *idau;
     uint32_t init_svtor;
+    bool enable_bitband;
 } ARMv7MState;
 
 #endif