hw/block/pflash_cfi02: Fix CFI in autoselect mode

After a flash device enters CFI mode from autoselect mode, the reset
command returns the device to autoselect mode. An additional reset
command is necessary to return to read array mode.

Signed-off-by: Stephen Checkoway <stephen.checkoway@oberlin.edu>
Message-Id: <20190426162624.55977-7-stephen.checkoway@oberlin.edu>
Tested-by: Philippe Mathieu-Daudé <philmd@redhat.com>
Acked-by: Thomas Huth <thuth@redhat.com>
Acked-by: Alistair Francis <alistair.francis@wdc.com>
Acked-by: Philippe Mathieu-Daudé <philmd@redhat.com>
Signed-off-by: Philippe Mathieu-Daudé <philmd@redhat.com>

hw/block/pflash_cfi02.c

@@ -66,6 +66,7 @@ do {                                                       \
 /* Special write cycles for CFI queries. */
 enum {
     WCYCLE_CFI              = 7,
+    WCYCLE_AUTOSELECT_CFI   = 8,
 };
 
 struct PFlashCFI02 {
@@ -311,6 +312,12 @@ static void pflash_write(void *opaque, hwaddr offset, uint64_t value,
     cmd = value;
     if (pfl->cmd != 0xA0) {
         if (cmd == 0xF0) {
+            if (pfl->wcycle == WCYCLE_AUTOSELECT_CFI) {
+                /* Return to autoselect mode. */
+                pfl->wcycle = 3;
+                pfl->cmd = 0x90;
+                return;
+            }
             goto reset_flash;
         }
     }
@@ -333,7 +340,6 @@ static void pflash_write(void *opaque, hwaddr offset, uint64_t value,
         /* We're in read mode */
     check_unlock0:
         if (boff == 0x55 && cmd == 0x98) {
-        enter_CFI_mode:
             /* Enter CFI query mode */
             pfl->wcycle = WCYCLE_CFI;
             pfl->cmd = 0x98;
@@ -410,9 +416,16 @@ static void pflash_write(void *opaque, hwaddr offset, uint64_t value,
                 /* Unlock bypass reset */
                 goto reset_flash;
             }
-            /* We can enter CFI query mode from autoselect mode */
+            /*
-            if (boff == 0x55 && cmd == 0x98)
+             * We can enter CFI query mode from autoselect mode, but we must
-                goto enter_CFI_mode;
+             * return to autoselect mode after a reset.
+             */
+            if (boff == 0x55 && cmd == 0x98) {
+                /* Enter autoselect CFI query mode */
+                pfl->wcycle = WCYCLE_AUTOSELECT_CFI;
+                pfl->cmd = 0x98;
+                return;
+            }
             /* No break here */
         default:
             DPRINTF("%s: invalid write for command %02x\n",
@@ -493,6 +506,7 @@ static void pflash_write(void *opaque, hwaddr offset, uint64_t value,
         break;
     /* Special values for CFI queries */
     case WCYCLE_CFI:
+    case WCYCLE_AUTOSELECT_CFI:
         DPRINTF("%s: invalid write in CFI query mode\n", __func__);
         goto reset_flash;
     default:

tests/pflash-cfi02-test.c

@@ -407,6 +407,42 @@ static void test_geometry(const void *opaque)
     qtest_quit(qtest);
 }
 
+/*
+ * Test that
+ * 1. enter autoselect mode;
+ * 2. enter CFI mode; and then
+ * 3. exit CFI mode
+ * leaves the flash device in autoselect mode.
+ */
+static void test_cfi_in_autoselect(const void *opaque)
+{
+    const FlashConfig *config = opaque;
+    QTestState *qtest;
+    qtest = qtest_initf("-M musicpal,accel=qtest"
+                        " -drive if=pflash,file=%s,format=raw,copy-on-read",
+                        image_path);
+    FlashConfig explicit_config = expand_config_defaults(config);
+    explicit_config.qtest = qtest;
+    const FlashConfig *c = &explicit_config;
+
+    /* 1. Enter autoselect. */
+    unlock(c);
+    flash_cmd(c, UNLOCK0_ADDR, AUTOSELECT_CMD);
+    g_assert_cmpint(flash_query(c, FLASH_ADDR(0)), ==, replicate(c, 0xBF));
+
+    /* 2. Enter CFI. */
+    flash_cmd(c, CFI_ADDR, CFI_CMD);
+    g_assert_cmpint(flash_query(c, FLASH_ADDR(0x10)), ==, replicate(c, 'Q'));
+    g_assert_cmpint(flash_query(c, FLASH_ADDR(0x11)), ==, replicate(c, 'R'));
+    g_assert_cmpint(flash_query(c, FLASH_ADDR(0x12)), ==, replicate(c, 'Y'));
+
+    /* 3. Exit CFI. */
+    reset(c);
+    g_assert_cmpint(flash_query(c, FLASH_ADDR(0)), ==, replicate(c, 0xBF));
+
+    qtest_quit(qtest);
+}
+
 static void cleanup(void *opaque)
 {
     unlink(image_path);
@@ -474,6 +510,9 @@ int main(int argc, char **argv)
         qtest_add_data_func(path, config, test_geometry);
         g_free(path);
     }
+
+    qtest_add_data_func("pflash-cfi02/cfi-in-autoselect", &configuration[0],
+                        test_cfi_in_autoselect);
     int result = g_test_run();
     cleanup(NULL);
     return result;