semihosting: enable chardev backed output for console

It will be useful for a number of use-cases to be able to re-direct
output to a file like we do with serial output. This does the wiring
to allow us to treat then semihosting console like just another
character output device.

Signed-off-by: Alex Bennée <alex.bennee@linaro.org>

2 files changed, 34 insertions, 1 deletions

diff --git a/hw/semihosting/config.c b/hw/semihosting/config.c
index f1d3fe1e4c..2a8e7e1045 100644
--- a/hw/semihosting/config.c
+++ b/hw/semihosting/config.c
@@ -23,6 +23,7 @@
 #include "qemu/config-file.h"
 #include "qemu/error-report.h"
 #include "hw/semihosting/semihost.h"
+#include "chardev/char.h"
 
 QemuOptsList qemu_semihosting_config_opts = {
     .name = "semihosting-config",
@@ -36,6 +37,9 @@ QemuOptsList qemu_semihosting_config_opts = {
             .name = "target",
             .type = QEMU_OPT_STRING,
         }, {
+            .name = "chardev",
+            .type = QEMU_OPT_STRING,
+        }, {
             .name = "arg",
             .type = QEMU_OPT_STRING,
         },
@@ -46,12 +50,14 @@ QemuOptsList qemu_semihosting_config_opts = {
 typedef struct SemihostingConfig {
     bool enabled;
     SemihostingTarget target;
+    Chardev *chardev;
     const char **argv;
     int argc;
     const char *cmdline; /* concatenated argv */
 } SemihostingConfig;
 
 static SemihostingConfig semihosting;
+static const char *semihost_chardev;
 
 bool semihosting_enabled(void)
 {
@@ -115,6 +121,11 @@ void semihosting_arg_fallback(const char *file, const char *cmd)
     }
 }
 
+Chardev *semihosting_get_chardev(void)
+{
+    return semihosting.chardev;
+}
+
 void qemu_semihosting_enable(void)
 {
     semihosting.enabled = true;
@@ -132,6 +143,8 @@ int qemu_semihosting_config_options(const char *optarg)
         semihosting.enabled = qemu_opt_get_bool(opts, "enable",
                                                 true);
         const char *target = qemu_opt_get(opts, "target");
+        /* setup of chardev is deferred until they are initialised */
+        semihost_chardev = qemu_opt_get(opts, "chardev");
         if (target != NULL) {
             if (strcmp("native", target) == 0) {
                 semihosting.target = SEMIHOSTING_TARGET_NATIVE;
@@ -158,3 +171,16 @@ int qemu_semihosting_config_options(const char *optarg)
     return 0;
 }
 
+void qemu_semihosting_connect_chardevs(void)
+{
+    /* We had to defer this until chardevs were created */
+    if (semihost_chardev) {
+        Chardev *chr = qemu_chr_find(semihost_chardev);
+        if (chr == NULL) {
+            error_report("semihosting chardev '%s' not found",
+                         semihost_chardev);
+            exit(1);
+        }
+        semihosting.chardev = chr;
+    }
+}
diff --git a/hw/semihosting/console.c b/hw/semihosting/console.c
index 01826bd687..466ea6dade 100644
--- a/hw/semihosting/console.c
+++ b/hw/semihosting/console.c
@@ -17,13 +17,20 @@
 
 #include "qemu/osdep.h"
 #include "cpu.h"
+#include "hw/semihosting/semihost.h"
 #include "hw/semihosting/console.h"
 #include "exec/gdbstub.h"
 #include "qemu/log.h"
+#include "chardev/char.h"
 
 int qemu_semihosting_log_out(const char *s, int len)
 {
-    return write(STDERR_FILENO, s, len);
+    Chardev *chardev = semihosting_get_chardev();
+    if (chardev) {
+        return qemu_chr_write_all(chardev, (uint8_t *) s, len);
+    } else {
+        return write(STDERR_FILENO, s, len);
+    }
 }
 
 /*