[Qemu-devel] [PATCH v2 06/10] block/pflash_cfi02: Fix CFI in autoselect mode

[Stephen Checkoway <stephen.checkoway@oberlin.edu>]

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>
---
 hw/block/pflash_cfi02.c   | 21 +++++++++++++++++----
 tests/pflash-cfi02-test.c | 36 ++++++++++++++++++++++++++++++++++++
 2 files changed, 53 insertions(+), 4 deletions(-)

diff --git a/hw/block/pflash_cfi02.c b/hw/block/pflash_cfi02.c
index c4efbe8cdf..be10036886 100644
--- a/hw/block/pflash_cfi02.c
+++ b/hw/block/pflash_cfi02.c
@@ -61,8 +61,9 @@ do {                                                       \
  */
 #define PFLASH_MAX_ERASE_REGIONS 4
 
-/* Special write cycle for CFI queries. */
+/* Special write cycles for CFI queries. */
 #define WCYCLE_CFI 7
+#define WCYCLE_AUTOSELECT_CFI 8
 
 struct PFlashCFI02 {
     /*< private >*/
@@ -325,6 +326,12 @@ static void pflash_write(void *opaque, hwaddr offset, uint64_t value,
         }
 
         if (cmd == 0xF0) {
+            if (pfl->wcycle == WCYCLE_AUTOSELECT_CFI) {
+                /* Return to autoselect mode. */
+                pfl->wcycle = 3;
+                pfl->cmd = 0x90;
+                return;
+            }
             goto reset_flash;
         }
     }
@@ -350,7 +357,6 @@ static void pflash_write(void *opaque, hwaddr offset, uint64_t value,
         /* We're in read mode */
     check_unlock0:
         if (masked_addr == 0x55 && cmd == 0x98) {
-        enter_CFI_mode:
             /* Enter CFI query mode */
             pfl->wcycle = WCYCLE_CFI;
             pfl->cmd = 0x98;
@@ -427,9 +433,15 @@ 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 */
+            /*
+             * We can enter CFI query mode from autoselect mode, but we must
+             * return to autoselect mode after a reset.
+             */
             if (masked_addr == 0x55 && cmd == 0x98) {
-                goto enter_CFI_mode;
+                /* Enter autoselect CFI query mode */
+                pfl->wcycle = WCYCLE_AUTOSELECT_CFI;
+                pfl->cmd = 0x98;
+                return;
             }
             /* No break here */
         default:
@@ -510,6 +522,7 @@ static void pflash_write(void *opaque, hwaddr offset, uint64_t value,
         }
         break;
     case WCYCLE_CFI: /* Special value for CFI queries */
+    case WCYCLE_AUTOSELECT_CFI:
         DPRINTF("%s: invalid write in CFI query mode\n", __func__);
         goto reset_flash;
     default:
diff --git a/tests/pflash-cfi02-test.c b/tests/pflash-cfi02-test.c
index dc85783a6a..ae1cd4e54b 100644
--- a/tests/pflash-cfi02-test.c
+++ b/tests/pflash-cfi02-test.c
@@ -437,6 +437,39 @@ static void test_geometry(const void *opaque)
     qtest_quit(global_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 *c = opaque;
+    global_qtest = qtest_initf("-M musicpal,accel=qtest"
+                               " -drive if=pflash,file=%s,format=raw,"
+                               "copy-on-read",
+                               image_path);
+
+    /* 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(global_qtest);
+}
+
 static void cleanup(void *opaque)
 {
     unlink(image_path);
@@ -562,6 +595,9 @@ 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;
-- 
2.20.1 (Apple Git-117)