[PATCH v4 4/4] hw/block/m25p80: Fix Numonyx fast read dummy cycle count

[Joe Komlodi <joe.komlodi@xilinx.com>]

Numonyx chips determine the number of cycles to wait based on bits 7:4
in the volatile configuration register.

However, if these bits are 0x0 or 0xF, the number of dummy cycles to
wait is
10 on a QIOR or QIOR4 command, or 8 on any other currently supported
fast read command. [1]

[1]
https://www.micron.com/-/media/client/global/documents/products/data-sheet/nor-flash/serial-nor/mt25q/die-rev-b/mt25q_qlkt_u_02g_cbb_0.pdf?rev=9b167fbf2b3645efba6385949a72e453

Signed-off-by: Joe Komlodi <komlodi@xilinx.com>
---
 hw/block/m25p80.c | 30 +++++++++++++++++++++++++++---
 1 file changed, 27 insertions(+), 3 deletions(-)

diff --git a/hw/block/m25p80.c b/hw/block/m25p80.c
index 2552f2c..0c78015 100644
--- a/hw/block/m25p80.c
+++ b/hw/block/m25p80.c
@@ -837,6 +837,30 @@ static uint8_t numonyx_get_mode(Flash *s)
     }
 }
 
+static uint8_t numonyx_extract_cfg_num_dummies(Flash *s)
+{
+    uint8_t num_dummies;
+    uint8_t mode;
+    assert(get_man(s) == MAN_NUMONYX);
+
+    mode = numonyx_get_mode(s);
+    num_dummies = extract32(s->volatile_cfg, 4, 4);
+
+    if (num_dummies == 0x0 || num_dummies == 0xf) {
+        switch (s->cmd_in_progress) {
+        case QIOR:
+        case QIOR4:
+            num_dummies = 10;
+            break;
+        default:
+            num_dummies = (mode == MODE_QIO) ? 10 : 8;
+            break;
+        }
+    }
+
+    return num_dummies;
+}
+
 static void decode_fast_read_cmd(Flash *s)
 {
     s->needed_bytes = get_addr_length(s);
@@ -847,7 +871,7 @@ static void decode_fast_read_cmd(Flash *s)
         s->state = STATE_COLLECTING_DATA;
         break;
     case MAN_NUMONYX:
-        s->needed_bytes += extract32(s->volatile_cfg, 4, 4);
+        s->needed_bytes += numonyx_extract_cfg_num_dummies(s);
         s->state = STATE_COLLECTING_DATA;
         break;
     case MAN_MACRONIX:
@@ -891,7 +915,7 @@ static void decode_dio_read_cmd(Flash *s)
         s->state = STATE_COLLECTING_DATA;
         break;
     case MAN_NUMONYX:
-        s->needed_bytes += extract32(s->volatile_cfg, 4, 4);
+        s->needed_bytes += numonyx_extract_cfg_num_dummies(s);
         s->state = STATE_COLLECTING_DATA;
         break;
     case MAN_MACRONIX:
@@ -935,7 +959,7 @@ static void decode_qio_read_cmd(Flash *s)
         s->state = STATE_COLLECTING_DATA;
         break;
     case MAN_NUMONYX:
-        s->needed_bytes += extract32(s->volatile_cfg, 4, 4);
+        s->needed_bytes += numonyx_extract_cfg_num_dummies(s);
         s->state = STATE_COLLECTING_DATA;
         break;
     case MAN_MACRONIX:
-- 
2.7.4