[PATCH 2/3] m25p80: Improve command handling for Jedec and unsupported commands

[Guenter Roeck <linux@roeck-us.net>]

Always report 6 bytes of JEDEC data. Fill remaining data with 0.

For unsupported commands, keep sending a value of 0 until the chip
is deselected.

Both changes avoid attempts to decode random commands. Up to now this
happened if the reported Jedec data was shorter than 6 bytes but the
host read 6 bytes, and with all unsupported commands.

Signed-off-by: Guenter Roeck <linux@roeck-us.net>
---
 hw/block/m25p80.c | 10 +++++++++-
 1 file changed, 9 insertions(+), 1 deletion(-)

diff --git a/hw/block/m25p80.c b/hw/block/m25p80.c
index 63e050d7d3..aca75edcc1 100644
--- a/hw/block/m25p80.c
+++ b/hw/block/m25p80.c
@@ -1040,8 +1040,11 @@ static void decode_new_cmd(Flash *s, uint32_t value)
         for (i = 0; i < s->pi->id_len; i++) {
             s->data[i] = s->pi->id[i];
         }
+        for (; i < SPI_NOR_MAX_ID_LEN; i++) {
+            s->data[i] = 0;
+        }
 
-        s->len = s->pi->id_len;
+        s->len = SPI_NOR_MAX_ID_LEN;
         s->pos = 0;
         s->state = STATE_READING_DATA;
         break;
@@ -1158,6 +1161,11 @@ static void decode_new_cmd(Flash *s, uint32_t value)
         s->quad_enable = false;
         break;
     default:
+        s->pos = 0;
+        s->len = 1;
+        s->state = STATE_READING_DATA;
+        s->data_read_loop = true;
+        s->data[0] = 0;
         qemu_log_mask(LOG_GUEST_ERROR, "M25P80: Unknown cmd %x\n", value);
         break;
     }
-- 
2.17.1