q800: add a block backend to the PRAM

This allows to save and restore the content of the PRAM.
It may be useful if we want to check the configuration or to change it.

The backend is added using mtd interface, for instance:

    ... -drive file=pram.img,format=raw,if=mtd ...

where pram.img is the file where the data will be stored, its size must
be 256 bytes.

Signed-off-by: Laurent Vivier <laurent@vivier.eu>
Message-Id: <20191219201439.84804-3-laurent@vivier.eu>

3 files changed, 74 insertions, 0 deletions

diff --git a/hw/m68k/q800.c b/hw/m68k/q800.c
index 4ca8678007..0c445c74bf 100644
--- a/hw/m68k/q800.c
+++ b/hw/m68k/q800.c
@@ -158,6 +158,7 @@ static void q800_init(MachineState *machine)
     NubusBus *nubus;
     GLUEState *irq;
     qemu_irq *pic;
+    DriveInfo *dinfo;
 
     linux_boot = (kernel_filename != NULL);
 
@@ -200,6 +201,11 @@ static void q800_init(MachineState *machine)
     /* VIA */
 
     via_dev = qdev_create(NULL, TYPE_MAC_VIA);
+    dinfo = drive_get(IF_MTD, 0, 0);
+    if (dinfo) {
+        qdev_prop_set_drive(via_dev, "drive", blk_by_legacy_dinfo(dinfo),
+                            &error_abort);
+    }
     qdev_init_nofail(via_dev);
     sysbus = SYS_BUS_DEVICE(via_dev);
     sysbus_mmio_map(sysbus, 0, VIA_BASE);
diff --git a/hw/misc/mac_via.c b/hw/misc/mac_via.c
index e5658af922..e9e6a95eab 100644
--- a/hw/misc/mac_via.c
+++ b/hw/misc/mac_via.c
@@ -27,6 +27,8 @@
 #include "sysemu/runstate.h"
 #include "qapi/error.h"
 #include "qemu/cutils.h"
+#include "hw/qdev-properties.h"
+#include "sysemu/block-backend.h"
 #include "trace.h"
 
 /*
@@ -375,6 +377,15 @@ static void via2_irq_request(void *opaque, int irq, int level)
     mdc->update_irq(s);
 }
 
+
+static void pram_update(MacVIAState *m)
+{
+    if (m->blk) {
+        blk_pwrite(m->blk, 0, m->mos6522_via1.PRAM,
+                   sizeof(m->mos6522_via1.PRAM), 0);
+    }
+}
+
 /*
  * RTC Commands
  *
@@ -547,6 +558,7 @@ static void via1_rtc_update(MacVIAState *m)
             /* PRAM address 0x00 -> 0x13 */
             trace_via1_rtc_cmd_pram_write(m->cmd - REG_PRAM_ADDR, m->data_out);
             v1s->PRAM[m->cmd - REG_PRAM_ADDR] = m->data_out;
+            pram_update(m);
             m->cmd = REG_EMPTY;
             break;
         case REG_PRAM_SECT...REG_PRAM_SECT_LAST:
@@ -577,6 +589,7 @@ static void via1_rtc_update(MacVIAState *m)
     g_assert(REG_PRAM_SECT <= m->cmd && m->cmd <= REG_PRAM_SECT_LAST);
     sector = m->cmd - REG_PRAM_SECT;
     v1s->PRAM[sector * 32 + m->alt] = m->data_out;
+    pram_update(m);
     trace_via1_rtc_cmd_pram_sect_write(sector, m->alt, sector * 32 + m->alt,
                                        m->data_out);
     m->alt = REG_EMPTY;
@@ -857,6 +870,7 @@ static void mac_via_realize(DeviceState *dev, Error **errp)
     MacVIAState *m = MAC_VIA(dev);
     MOS6522State *ms;
     struct tm tm;
+    int ret;
 
     /* Init VIAs 1 and 2 */
     sysbus_init_child_obj(OBJECT(dev), "via1", &m->mos6522_via1,
@@ -890,6 +904,28 @@ static void mac_via_realize(DeviceState *dev, Error **errp)
     m->adb_poll_timer = timer_new_ns(QEMU_CLOCK_VIRTUAL, via_adb_poll, m);
     m->adb_data_ready = qdev_get_gpio_in_named(dev, "via1-irq",
                                                VIA1_IRQ_ADB_READY_BIT);
+
+    if (m->blk) {
+        int64_t len = blk_getlength(m->blk);
+        if (len < 0) {
+            error_setg_errno(errp, -len,
+                             "could not get length of backing image");
+            return;
+        }
+        ret = blk_set_perm(m->blk,
+                           BLK_PERM_CONSISTENT_READ | BLK_PERM_WRITE,
+                           BLK_PERM_ALL, errp);
+        if (ret < 0) {
+            return;
+        }
+
+        len = blk_pread(m->blk, 0, m->mos6522_via1.PRAM,
+                        sizeof(m->mos6522_via1.PRAM));
+        if (len != sizeof(m->mos6522_via1.PRAM)) {
+            error_setg(errp, "can't read PRAM contents");
+            return;
+        }
+    }
 }
 
 static void mac_via_init(Object *obj)
@@ -914,10 +950,33 @@ static void mac_via_init(Object *obj)
                         TYPE_ADB_BUS, DEVICE(obj), "adb.0");
 }
 
+static void postload_update_cb(void *opaque, int running, RunState state)
+{
+    MacVIAState *m = MAC_VIA(opaque);
+
+    qemu_del_vm_change_state_handler(m->vmstate);
+    m->vmstate = NULL;
+
+    pram_update(m);
+}
+
+static int mac_via_post_load(void *opaque, int version_id)
+{
+    MacVIAState *m = MAC_VIA(opaque);
+
+    if (m->blk) {
+        m->vmstate = qemu_add_vm_change_state_handler(postload_update_cb,
+                                                      m);
+    }
+
+    return 0;
+}
+
 static const VMStateDescription vmstate_mac_via = {
     .name = "mac-via",
     .version_id = 1,
     .minimum_version_id = 1,
+    .post_load = mac_via_post_load,
     .fields = (VMStateField[]) {
         /* VIAs */
         VMSTATE_STRUCT(mos6522_via1.parent_obj, MacVIAState, 0, vmstate_mos6522,
@@ -950,6 +1009,11 @@ static const VMStateDescription vmstate_mac_via = {
     }
 };
 
+static Property mac_via_properties[] = {
+    DEFINE_PROP_DRIVE("drive", MacVIAState, blk),
+    DEFINE_PROP_END_OF_LIST(),
+};
+
 static void mac_via_class_init(ObjectClass *oc, void *data)
 {
     DeviceClass *dc = DEVICE_CLASS(oc);
@@ -957,6 +1021,7 @@ static void mac_via_class_init(ObjectClass *oc, void *data)
     dc->realize = mac_via_realize;
     dc->reset = mac_via_reset;
     dc->vmsd = &vmstate_mac_via;
+    dc->props = mac_via_properties;
 }
 
 static TypeInfo mac_via_info = {
diff --git a/include/hw/misc/mac_via.h b/include/hw/misc/mac_via.h
index 3f86fcb7e1..e74f85be0f 100644
--- a/include/hw/misc/mac_via.h
+++ b/include/hw/misc/mac_via.h
@@ -81,6 +81,8 @@ typedef struct MOS6522Q800VIA2State {
 typedef struct MacVIAState {
     SysBusDevice busdev;
 
+    VMChangeStateEntry *vmstate;
+
     /* MMIO */
     MemoryRegion mmio;
     MemoryRegion via1mem;
@@ -100,6 +102,7 @@ typedef struct MacVIAState {
     uint8_t cmd;
     int wprotect;
     int alt;
+    BlockBackend *blk;
 
     /* ADB */
     ADBBusState adb_bus;