[PATCH] ssi: Display chip select polarity in monitor 'info qtree'

[Philippe Mathieu-Daudé]

It is sometime useful to verify a device chip select polarity
on a SPI bus. Since we have this information available, display
it in the 'info qtree' monitor output:

  $ qemu-system-arm -M lm3s6965evb -monitor stdio -S
  (qemu) info qtree
  [...]
  dev: pl022, id ""
    gpio-out "sysbus-irq" 1
    mmio 0000000040008000/0000000000001000
    bus: ssi
      type SSI
      dev: ssd0323, id ""
        gpio-in "" 1
        gpio-in "ssi-gpio-cs" 1
        chip select polarity: high           <---
      dev: ssi-sd, id ""
        gpio-in "ssi-gpio-cs" 1
        chip select polarity: low            <---
        bus: sd-bus
          type sd-bus
          dev: sd-card, id ""
            spec_version = 2 (0x2)
            drive = "sd0"
            spi = true

Signed-off-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
---
 hw/ssi/ssi.c | 22 ++++++++++++++++++++++
 1 file changed, 22 insertions(+)

diff --git a/hw/ssi/ssi.c b/hw/ssi/ssi.c
index 4278d0e4440..4c9f8d66d23 100644
--- a/hw/ssi/ssi.c
+++ b/hw/ssi/ssi.c
@@ -17,6 +17,7 @@
 #include "migration/vmstate.h"
 #include "qemu/module.h"
 #include "qapi/error.h"
+#include "monitor/monitor.h"
 #include "qom/object.h"
 
 struct SSIBus {
@@ -26,10 +27,31 @@ struct SSIBus {
 #define TYPE_SSI_BUS "SSI"
 OBJECT_DECLARE_SIMPLE_TYPE(SSIBus, SSI_BUS)
 
+static void ssi_print_dev(Monitor *mon, DeviceState *dev, int indent)
+{
+    static const char *const polarity_s[] = {
+        [SSI_CS_NONE] = "unknown",
+        [SSI_CS_LOW]  = "low",
+        [SSI_CS_HIGH] = "high"
+    };
+    SSISlaveClass *ssc = SSI_SLAVE_GET_CLASS(dev);
+
+    monitor_printf(mon, "%*schip select polarity: %s\n",
+                   indent, "", polarity_s[ssc->cs_polarity]);
+}
+
+static void ssi_bus_class_init(ObjectClass *klass, void *data)
+{
+    BusClass *k = BUS_CLASS(klass);
+
+    k->print_dev = ssi_print_dev;
+}
+
 static const TypeInfo ssi_bus_info = {
     .name = TYPE_SSI_BUS,
     .parent = TYPE_BUS,
     .instance_size = sizeof(SSIBus),
+    .class_init = ssi_bus_class_init,
 };
 
 static void ssi_cs_default(void *opaque, int n, int level)
-- 
2.26.2