[PATCH 1/2] m25p80: Add basic support for the SFDP command

[Cédric Le Goater]

JEDEC STANDARD JESD216 for Serial Flash Discovery Parameters (SFDP)
provides a mean to describe the features of a serial flash device
using a set of internal parameter tables.

This is the initial framework for the RDSFDP command giving access to
a private SFDP area under the flash. This area now needs to be
populated with the flash device characteristics, using a new 'sfdp'
pointer under FlashPartInfo.

Signed-off-by: Cédric Le Goater <clg@kaod.org>
---
 hw/block/m25p80_sfdp.h | 15 +++++++++++++++
 hw/block/m25p80.c      | 33 +++++++++++++++++++++++++++++++++
 hw/block/trace-events  |  1 +
 3 files changed, 49 insertions(+)
 create mode 100644 hw/block/m25p80_sfdp.h

diff --git a/hw/block/m25p80_sfdp.h b/hw/block/m25p80_sfdp.h
new file mode 100644
index 000000000000..b75fd0b0c13f
--- /dev/null
+++ b/hw/block/m25p80_sfdp.h
@@ -0,0 +1,15 @@
+/*
+ * M25P80 SFDP
+ *
+ * Copyright (c) 2020, IBM Corporation.
+ *
+ * This code is licensed under the GPL version 2 or later. See the
+ * COPYING file in the top-level directory.
+ */
+
+#ifndef HW_M25P80_SFDP_H
+#define HW_M25P80_SFDP_H
+
+#define M25P80_SFDP_AREA_SIZE 0x100
+
+#endif
diff --git a/hw/block/m25p80.c b/hw/block/m25p80.c
index 82270884416e..32925589ec7a 100644
--- a/hw/block/m25p80.c
+++ b/hw/block/m25p80.c
@@ -33,6 +33,7 @@
 #include "qemu/error-report.h"
 #include "qapi/error.h"
 #include "trace.h"
+#include "m25p80_sfdp.h"
 
 /* Fields for FlashPartInfo->flags */
 
@@ -72,6 +73,7 @@ typedef struct FlashPartInfo {
      * This field inform how many die is in the chip.
      */
     uint8_t die_cnt;
+    const uint8_t *sfdp;
 } FlashPartInfo;
 
 /* adapted from linux */
@@ -333,6 +335,7 @@ typedef enum {
     BULK_ERASE = 0xc7,
     READ_FSR = 0x70,
     RDCR = 0x15,
+    RDSFDP = 0x5a,
 
     READ = 0x03,
     READ4 = 0x13,
@@ -398,6 +401,7 @@ typedef enum {
     STATE_COLLECTING_DATA,
     STATE_COLLECTING_VAR_LEN_DATA,
     STATE_READING_DATA,
+    STATE_READING_SFDP,
 } CMDState;
 
 typedef enum {
@@ -619,6 +623,8 @@ static inline int get_addr_length(Flash *s)
     }
 
    switch (s->cmd_in_progress) {
+   case RDSFDP:
+       return 3;
    case PP4:
    case PP4_4:
    case QPP_4:
@@ -744,6 +750,17 @@ static void complete_collecting_data(Flash *s)
                           " by device\n");
         }
         break;
+
+    case RDSFDP:
+        if (s->cur_addr < M25P80_SFDP_AREA_SIZE) {
+            s->state = STATE_READING_SFDP;
+        } else {
+            qemu_log_mask(LOG_GUEST_ERROR,
+                          "M25P80: Invalid SFDP address %#" PRIx32 "\n",
+                          s->cur_addr);
+        }
+        break;
+
     default:
         break;
     }
@@ -1160,6 +1177,16 @@ static void decode_new_cmd(Flash *s, uint32_t value)
     case RSTQIO:
         s->quad_enable = false;
         break;
+    case RDSFDP:
+        if (s->pi->sfdp) {
+            s->needed_bytes = get_addr_length(s) + 1 ; /* SFDP addr + dummy */
+            s->pos = 0;
+            s->len = 0;
+            s->state = STATE_COLLECTING_DATA;
+            break;
+        }
+        /* Fallthrough */
+
     default:
         s->pos = 0;
         s->len = 1;
@@ -1256,6 +1283,12 @@ static uint32_t m25p80_transfer8(SSISlave *ss, uint32_t 
tx)
             }
         }
         break;
+    case STATE_READING_SFDP:
+        assert(s->pi->sfdp);
+        r = s->pi->sfdp[s->cur_addr];
+        trace_m25p80_read_sfdp(s, s->cur_addr, (uint8_t)r);
+        s->cur_addr = (s->cur_addr + 1) & (M25P80_SFDP_AREA_SIZE - 1);
+        break;
 
     default:
     case STATE_IDLE:
diff --git a/hw/block/trace-events b/hw/block/trace-events
index 958fcc5508d1..53d377ca2b46 100644
--- a/hw/block/trace-events
+++ b/hw/block/trace-events
@@ -152,5 +152,6 @@ m25p80_page_program(void *s, uint32_t addr, uint8_t tx) 
"[%p] page program cur_a
 m25p80_transfer(void *s, uint8_t state, uint32_t len, uint8_t needed, uint32_t 
pos, uint32_t cur_addr, uint8_t t) "[%p] Transfer state 0x%"PRIx8" len 
0x%"PRIx32" needed 0x%"PRIx8" pos 0x%"PRIx32" addr 0x%"PRIx32" tx 0x%"PRIx8
 m25p80_read_byte(void *s, uint32_t addr, uint8_t v) "[%p] Read byte 
0x%"PRIx32"=0x%"PRIx8
 m25p80_read_data(void *s, uint32_t pos, uint8_t v) "[%p] Read data 
0x%"PRIx32"=0x%"PRIx8
+m25p80_read_sfdp(void *s, uint32_t addr, uint8_t v) "[%p] Read SFDP 
0x%"PRIx32"=0x%"PRIx8
 m25p80_binding(void *s) "[%p] Binding to IF_MTD drive"
 m25p80_binding_no_bdrv(void *s) "[%p] No BDRV - binding to RAM"
-- 
2.25.4