hw/ssi: imx_spi: Rework imx_spi_write() to handle block disabled

When the block is disabled, only the ECSPI_CONREG register can
be modified. Setting the EN bit enabled the device, clearing it
"disables the block and resets the internal logic with the
exception of the ECSPI_CONREG" register.

Ignore all other registers write except ECSPI_CONREG when the
block is disabled.

Ref: i.MX 6DQ Applications Processor Reference Manual (IMX6DQRM),
     chapter 21.7.3: Control Register (ECSPIx_CONREG)

Signed-off-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
Signed-off-by: Bin Meng <bin.meng@windriver.com>
Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
Message-id: 20210129132323.30946-7-bmeng.cn@gmail.com
Message-Id: <20210115153049.3353008-6-f4bug@amsat.org>
Signed-off-by: Bin Meng <bin.meng@windriver.com>
Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>

1 files changed, 9 insertions, 4 deletions

diff --git a/hw/ssi/imx_spi.c b/hw/ssi/imx_spi.c
index 21e2c9dea3..4cfbb73e35 100644
--- a/hw/ssi/imx_spi.c
+++ b/hw/ssi/imx_spi.c
@@ -332,6 +332,14 @@ static void imx_spi_write(void *opaque, hwaddr offset, uint64_t value,
     DPRINTF("reg[%s] <= 0x%" PRIx32 "\n", imx_spi_reg_name(index),
             (uint32_t)value);
 
+    if (!imx_spi_is_enabled(s)) {
+        /* Block is disabled */
+        if (index != ECSPI_CONREG) {
+            /* Ignore access */
+            return;
+        }
+    }
+
     change_mask = s->regs[index] ^ value;
 
     switch (index) {
@@ -340,10 +348,7 @@ static void imx_spi_write(void *opaque, hwaddr offset, uint64_t value,
                       TYPE_IMX_SPI, __func__);
         break;
     case ECSPI_TXDATA:
-        if (!imx_spi_is_enabled(s)) {
-            /* Ignore writes if device is disabled */
-            break;
-        } else if (fifo32_is_full(&s->tx_fifo)) {
+        if (fifo32_is_full(&s->tx_fifo)) {
             /* Ignore writes if queue is full */
             break;
         }