[Qemu-devel] [PATCH-for-4.1 v6 5/5] hw/block/pflash_cfi01: Add the DeviceReset() handler

[Philippe Mathieu-Daudé]

A "system reset" sets the device state machine in READ_ARRAY mode
and, after some delay, set the SR.7 READY bit.

We do not model timings, so we set the SR.7 bit directly.

The TYPE_DEVICE interface provides a DeviceReset handler.
This pflash device is a subclass of TYPE_SYS_BUS_DEVICE (which
is a subclass of TYPE_DEVICE).
SYS_BUS devices are automatically plugged into the 'main system
bus', which is the root of the qbus tree.
Devices in the qbus tree are guaranteed to have their reset()
handler called after realize() and before we try to run the guest.

To avoid incoherent states when the machine resets (see but report
below), factor out the reset code into pflash_cfi01_system_reset,
and register the method as a device reset callback.

Buglink: https://bugzilla.redhat.com/show_bug.cgi?id=1678713
Reported-by: Laszlo Ersek <address@hidden>
Reviewed-by: John Snow <address@hidden>
Reviewed-by: Alistair Francis <address@hidden>
Signed-off-by: Philippe Mathieu-Daudé <address@hidden>
---
v6: dropped Laszlo's Regression-tested-by tag
---
 hw/block/pflash_cfi01.c | 15 +++++++++++++--
 1 file changed, 13 insertions(+), 2 deletions(-)

diff --git a/hw/block/pflash_cfi01.c b/hw/block/pflash_cfi01.c
index 65afdbf3a7..ee0ed70242 100644
--- a/hw/block/pflash_cfi01.c
+++ b/hw/block/pflash_cfi01.c
@@ -768,8 +768,6 @@ static void pflash_cfi01_realize(DeviceState *dev, Error 
**errp)
         pfl->max_device_width = pfl->device_width;
     }
 
-    pflash_mode_read_array(pfl);
-    pfl->status = 0x80; /* WSM ready */
     /* Hardcoded CFI table */
     /* Standard "QRY" string */
     pfl->cfi_table[0x10] = 'Q';
@@ -857,6 +855,18 @@ static void pflash_cfi01_realize(DeviceState *dev, Error 
**errp)
     pfl->cfi_table[0x3f] = 0x01; /* Number of protection fields */
 }
 
+static void pflash_cfi01_system_reset(DeviceState *dev)
+{
+    PFlashCFI01 *pfl = PFLASH_CFI01(dev);
+
+    pflash_mode_read_array(pfl);
+    /*
+     * The WSM ready timer occurs at most 150ns after system reset.
+     * This model deliberately ignores this delay.
+     */
+    pfl->status = 0x80;
+}
+
 static Property pflash_cfi01_properties[] = {
     DEFINE_PROP_DRIVE("drive", PFlashCFI01, blk),
     /* num-blocks is the number of blocks actually visible to the guest,
@@ -901,6 +911,7 @@ static void pflash_cfi01_class_init(ObjectClass *klass, 
void *data)
 {
     DeviceClass *dc = DEVICE_CLASS(klass);
 
+    dc->reset = pflash_cfi01_system_reset;
     dc->realize = pflash_cfi01_realize;
     dc->props = pflash_cfi01_properties;
     dc->vmsd = &vmstate_pflash;
-- 
2.20.1