Fixes for QSPI to make sure its properly reset before use

Author: dgarske

hal/zynq.c

@@ -1359,6 +1359,36 @@ static int qspi_exit_4byte_addr(QspiDev_t* dev)
 }
 #endif
 
+/* Soft-reset the flash to a known idle state.
+ * FSBL / BootROM may leave the flash in an unexpected mode (XIP enabled,
+ * 4-byte addr set, auto-boot probing, etc.). Issue RESET_ENABLE (0x66) +
+ * RESET_MEMORY (0x99) to bring it back to defaults before first transaction.
+ * Per Micron MT25Q datasheet: t_SHSL2 ~ 40 us max after RESET_MEMORY. */
+static int qspi_flash_reset(QspiDev_t* dev)
+{
+    int ret;
+    uint8_t cmd[4]; /* size multiple of uint32_t */
+
+    memset(cmd, 0, sizeof(cmd));
+    cmd[0] = RESET_ENABLE_CMD;
+    ret = qspi_transfer(dev, cmd, 1, NULL, 0, NULL, 0, 0,
+        GQSPI_GEN_FIFO_MODE_SPI);
+#if defined(DEBUG_ZYNQ) && DEBUG_ZYNQ >= 2
+    wolfBoot_printf("Flash Reset Enable: Ret %d\n", ret);
+#endif
+    if (ret == GQSPI_CODE_SUCCESS) {
+        cmd[0] = RESET_MEMORY_CMD;
+        ret = qspi_transfer(dev, cmd, 1, NULL, 0, NULL, 0, 0,
+            GQSPI_GEN_FIFO_MODE_SPI);
+    #if defined(DEBUG_ZYNQ) && DEBUG_ZYNQ >= 2
+        wolfBoot_printf("Flash Reset Memory: Ret %d\n", ret);
+    #endif
+    }
+    /* Allow flash time to complete the reset and become ready. */
+    hal_delay_ms(1);
+    return ret;
+}
+
 /* QSPI functions */
 void qspi_init(void)
 {
@@ -1499,6 +1529,19 @@ void qspi_init(void)
     (void)reg_cfg;
     (void)reg_isr;
 
+    /* Issue flash soft reset so we start from a known state regardless of
+     * whatever mode FSBL/BootROM left the device in. Send to each chip in
+     * dual-parallel configurations by targeting both chip selects. */
+    mDev.mode = GQSPI_GEN_FIFO_MODE_SPI;
+    mDev.bus = GQSPI_GEN_FIFO_BUS_LOW;
+    mDev.cs = GQSPI_GEN_FIFO_CS_LOWER;
+    (void)qspi_flash_reset(&mDev);
+#if GQPI_USE_DUAL_PARALLEL == 1
+    mDev.bus = GQSPI_GEN_FIFO_BUS_UP;
+    mDev.cs = GQSPI_GEN_FIFO_CS_UPPER;
+    (void)qspi_flash_reset(&mDev);
+#endif
+
     /* ------ Flash Read ID (retry) ------ */
     timeout = 0;
     while (++timeout < QSPI_FLASH_READY_TRIES) {