[PATCH v9 04/10] hw/ssi: imx_spi: Rework imx_spi_reset() to keep CONREG register value

[Bin Meng <bmeng.cn@gmail.com>]

From: Philippe Mathieu-Daudé <f4bug@amsat.org>

When the block is disabled, all registers are reset with the
exception of the ECSPI_CONREG. It is initialized to zero
when the instance is created.

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>
[bmeng: add a 'common_reset' function that does most of reset operation]
Signed-off-by: Bin Meng <bin.meng@windriver.com>

---

Changes in v9:
- Add a 'common_reset' function that does most of reset operation,
  leaving ECSPI_CONREG clear in imx_spi_reset().

Changes in v7:
- remove the RFC tag

Changes in v6:
- new patch: [RFC] rework imx_spi_reset() to keep CONREG register value

 hw/ssi/imx_spi.c | 32 ++++++++++++++++++++++++--------
 1 file changed, 24 insertions(+), 8 deletions(-)

diff --git a/hw/ssi/imx_spi.c b/hw/ssi/imx_spi.c
index 8fb3c9b6d1..e85be6ae60 100644
--- a/hw/ssi/imx_spi.c
+++ b/hw/ssi/imx_spi.c
@@ -228,15 +228,23 @@ static void imx_spi_flush_txfifo(IMXSPIState *s)
             fifo32_num_used(&s->tx_fifo), fifo32_num_used(&s->rx_fifo));
 }
 
-static void imx_spi_reset(DeviceState *dev)
+static void imx_spi_common_reset(IMXSPIState *s)
 {
-    IMXSPIState *s = IMX_SPI(dev);
-
-    DPRINTF("\n");
-
-    memset(s->regs, 0, sizeof(s->regs));
+    int i;
 
-    s->regs[ECSPI_STATREG] = 0x00000003;
+    for (i = 0; i < ARRAY_SIZE(s->regs); i++) {
+        switch (i) {
+        case ECSPI_CONREG:
+            /* CONREG is not updated on soft reset */
+            break;
+        case ECSPI_STATREG:
+            s->regs[i] = 0x00000003;
+            break;
+        default:
+            s->regs[i] = 0;
+            break;
+        }
+    }
 
     imx_spi_rxfifo_reset(s);
     imx_spi_txfifo_reset(s);
@@ -246,11 +254,19 @@ static void imx_spi_reset(DeviceState *dev)
 
 static void imx_spi_soft_reset(IMXSPIState *s)
 {
-    imx_spi_reset(DEVICE(s));
+    imx_spi_common_reset(s);
 
     imx_spi_update_irq(s);
 }
 
+static void imx_spi_reset(DeviceState *dev)
+{
+    IMXSPIState *s = IMX_SPI(dev);
+
+    imx_spi_common_reset(s);
+    s->regs[ECSPI_CONREG] = 0;
+}
+
 static uint64_t imx_spi_read(void *opaque, hwaddr offset, unsigned size)
 {
     uint32_t value = 0;
-- 
2.25.1