hw/ssi: imx_spi: Use a macro for number of chip selects supported

Avoid using a magic number (4) everywhere for the number of chip
selects supported.

Signed-off-by: Bin Meng <bin.meng@windriver.com>
Reviewed-by: Alistair Francis <alistair.francis@wdc.com>
Reviewed-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
Reviewed-by: Juan Quintela <quintela@redhat.com>
Message-id: 20210129132323.30946-2-bmeng.cn@gmail.com
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>

hw/ssi/imx_spi.c

@@ -361,7 +361,7 @@ static void imx_spi_write(void *opaque, hwaddr offset, uint64_t value,
 
             /* We are in master mode */
 
-            for (i = 0; i < 4; i++) {
+            for (i = 0; i < ECSPI_NUM_CS; i++) {
                 qemu_set_irq(s->cs_lines[i],
                              i == imx_spi_selected_channel(s) ? 0 : 1);
             }
@@ -424,7 +424,7 @@ static void imx_spi_realize(DeviceState *dev, Error **errp)
     sysbus_init_mmio(SYS_BUS_DEVICE(dev), &s->iomem);
     sysbus_init_irq(SYS_BUS_DEVICE(dev), &s->irq);
 
-    for (i = 0; i < 4; ++i) {
+    for (i = 0; i < ECSPI_NUM_CS; ++i) {
         sysbus_init_irq(SYS_BUS_DEVICE(dev), &s->cs_lines[i]);
     }
 

include/hw/ssi/imx_spi.h

@@ -77,6 +77,9 @@
 
 #define EXTRACT(value, name) extract32(value, name##_SHIFT, name##_LENGTH)
 
+/* number of chip selects supported */
+#define ECSPI_NUM_CS 4
+
 #define TYPE_IMX_SPI "imx.spi"
 OBJECT_DECLARE_SIMPLE_TYPE(IMXSPIState, IMX_SPI)
 
@@ -89,7 +92,7 @@ struct IMXSPIState {
 
     qemu_irq irq;
 
-    qemu_irq cs_lines[4];
+    qemu_irq cs_lines[ECSPI_NUM_CS];
 
     SSIBus *bus;