[PATCH v2 11/12] aspeed: Introduce a "bmc-console" machine option

[Cédric Le Goater]

Most of the Aspeed machines use the UART5 device for the boot console,
and QEMU connects the first serial Chardev to this SoC device for this
purpose. See routine connect_serial_hds_to_uarts().

Nevertheless, some machines use another boot console, such as the fuji,
and commit 5d63d0c76c ("hw/arm/aspeed: Allow machine to set UART
default") introduced a SoC class attribute 'uart_default' and property
to be able to change the boot console device. It was later changed by
commit d2b3eaefb4 ("aspeed: Refactor UART init for multi-SoC machines").

The "bmc-console" machine option goes a step further and lets the user define
the UART device from the QEMU command line without introducing a new
machine definition. For instance, to use device UART3 (mapped on
/dev/ttyS2 under Linux) instead of the default UART5, one would use :

  -M ast2500-evb,bmc-console=uart3

Cc: Abhishek Singh Dagur <abhishek@drut.io>
Signed-off-by: Cédric Le Goater <clg@kaod.org>
---
 docs/system/arm/aspeed.rst | 11 +++++++++++
 hw/arm/aspeed.c            | 40 ++++++++++++++++++++++++++++++++++++--
 2 files changed, 49 insertions(+), 2 deletions(-)

diff --git a/docs/system/arm/aspeed.rst b/docs/system/arm/aspeed.rst
index d4e293e7f986..80538422a1a4 100644
--- a/docs/system/arm/aspeed.rst
+++ b/docs/system/arm/aspeed.rst
@@ -122,6 +122,11 @@ Options specific to Aspeed machines are :
 
  * ``spi-model`` to change the SPI Flash model.
 
+ * ``bmc-console`` to change the default console device. Most of the
+   machines use the ``UART5`` device for a boot console, which is
+   mapped on ``/dev/ttyS4`` under Linux, but it is not always the
+   case.
+
 For instance, to start the ``ast2500-evb`` machine with a different
 FMC chip and a bigger (64M) SPI chip, use :
 
@@ -129,6 +134,12 @@ FMC chip and a bigger (64M) SPI chip, use :
 
   -M ast2500-evb,fmc-model=mx25l25635e,spi-model=mx66u51235f
 
+To change the boot console and use device ``UART3`` (``/dev/ttyS2``
+under Linux), use :
+
+.. code-block:: bash
+
+  -M ast2500-evb,bmc-console=uart3
 
 Aspeed minibmc family boards (``ast1030-evb``)
 ==================================================================
diff --git a/hw/arm/aspeed.c b/hw/arm/aspeed.c
index 8beed0c2a66e..d3e58936e68a 100644
--- a/hw/arm/aspeed.c
+++ b/hw/arm/aspeed.c
@@ -43,6 +43,7 @@ struct AspeedMachineState {
     AspeedSoCState soc;
     MemoryRegion boot_rom;
     bool mmio_exec;
+    uint32_t uart_chosen;
     char *fmc_model;
     char *spi_model;
 };
@@ -331,10 +332,11 @@ static void 
connect_serial_hds_to_uarts(AspeedMachineState *bmc)
     AspeedMachineClass *amc = ASPEED_MACHINE_GET_CLASS(bmc);
     AspeedSoCState *s = &bmc->soc;
     AspeedSoCClass *sc = ASPEED_SOC_GET_CLASS(s);
+    int uart_chosen = bmc->uart_chosen ? bmc->uart_chosen : amc->uart_default;
 
-    aspeed_soc_uart_set_chr(s, amc->uart_default, serial_hd(0));
+    aspeed_soc_uart_set_chr(s, uart_chosen, serial_hd(0));
     for (int i = 1, uart = ASPEED_DEV_UART1; i < sc->uarts_num; i++, uart++) {
-        if (uart == amc->uart_default) {
+        if (uart == uart_chosen) {
             continue;
         }
         aspeed_soc_uart_set_chr(s, uart, serial_hd(i));
@@ -1079,6 +1081,35 @@ static void aspeed_set_spi_model(Object *obj, const char 
*value, Error **errp)
     bmc->spi_model = g_strdup(value);
 }
 
+static char *aspeed_get_bmc_console(Object *obj, Error **errp)
+{
+    AspeedMachineState *bmc = ASPEED_MACHINE(obj);
+    AspeedMachineClass *amc = ASPEED_MACHINE_GET_CLASS(bmc);
+    int uart_chosen = bmc->uart_chosen ? bmc->uart_chosen : amc->uart_default;
+
+    return g_strdup_printf("uart%d", uart_chosen - ASPEED_DEV_UART1 + 1);
+}
+
+static void aspeed_set_bmc_console(Object *obj, const char *value, Error 
**errp)
+{
+    AspeedMachineState *bmc = ASPEED_MACHINE(obj);
+    AspeedMachineClass *amc = ASPEED_MACHINE_GET_CLASS(bmc);
+    AspeedSoCClass *sc = ASPEED_SOC_CLASS(object_class_by_name(amc->soc_name));
+    int val;
+
+    if (sscanf(value, "uart%u", &val) != 1) {
+        error_setg(errp, "Bad value for \"uart\" property");
+        return;
+    }
+
+    /* The number of UART depends on the SoC */
+    if (val < 1 || val > sc->uarts_num) {
+        error_setg(errp, "\"uart\" should be in range [1 - %d]", 
sc->uarts_num);
+        return;
+    }
+    bmc->uart_chosen = ASPEED_DEV_UART1 + val - 1;
+}
+
 static void aspeed_machine_class_props_init(ObjectClass *oc)
 {
     object_class_property_add_bool(oc, "execute-in-place",
@@ -1087,6 +1118,11 @@ static void aspeed_machine_class_props_init(ObjectClass 
*oc)
     object_class_property_set_description(oc, "execute-in-place",
                            "boot directly from CE0 flash device");
 
+    object_class_property_add_str(oc, "bmc-console", aspeed_get_bmc_console,
+                                  aspeed_set_bmc_console);
+    object_class_property_set_description(oc, "bmc-console",
+                           "Change the default UART to \"uartX\"");
+
     object_class_property_add_str(oc, "fmc-model", aspeed_get_fmc_model,
                                    aspeed_set_fmc_model);
     object_class_property_set_description(oc, "fmc-model",
-- 
2.40.1