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authorPeter Maydell <peter.maydell@linaro.org>2022-02-08 17:16:43 +0000
committerPeter Maydell <peter.maydell@linaro.org>2022-02-21 13:30:20 +0000
commit542e87c7a2d90076b07611987fd3d789865e5ea1 (patch)
treeddd411355744af09ea0ca99b76a846b2c743c4ad
parente117e9748f6946dcddfea6f157f9ab2b5f069f70 (diff)
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hw/arm/armv7m: Handle disconnected clock inputs
In the armv7m object, handle clock inputs that aren't connected. This is always an error for 'cpuclk'. For 'refclk' it is OK for this to be disconnected, but we need to handle it by not trying to connect a sourceless-clock to the systick device. This fixes a bug where on the mps2-an521 and similar boards (which do not have a refclk) the systick device incorrectly reset with SYST_CSR.CLKSOURCE 0 ("use refclk") rather than 1 ("use CPU clock"). Cc: qemu-stable@nongnu.org Reported-by: Richard Petri <git@rpls.de> Signed-off-by: Peter Maydell <peter.maydell@linaro.org> Reviewed-by: Philippe Mathieu-Daudé <f4bug@amsat.org> Reviewed-by: Richard Henderson <richard.henderson@linaro.org> Message-id: 20220208171643.3486277-1-peter.maydell@linaro.org
-rw-r--r--hw/arm/armv7m.c26
1 files changed, 22 insertions, 4 deletions
diff --git a/hw/arm/armv7m.c b/hw/arm/armv7m.c
index ceb76df..41cfca0 100644
--- a/hw/arm/armv7m.c
+++ b/hw/arm/armv7m.c
@@ -284,6 +284,12 @@ static void armv7m_realize(DeviceState *dev, Error **errp)
return;
}
+ /* cpuclk must be connected; refclk is optional */
+ if (!clock_has_source(s->cpuclk)) {
+ error_setg(errp, "armv7m: cpuclk must be connected");
+ return;
+ }
+
memory_region_add_subregion_overlap(&s->container, 0, s->board_memory, -1);
s->cpu = ARM_CPU(object_new_with_props(s->cpu_type, OBJECT(s), "cpu",
@@ -420,8 +426,18 @@ static void armv7m_realize(DeviceState *dev, Error **errp)
&s->sysreg_ns_mem);
}
- /* Create and map the systick devices */
- qdev_connect_clock_in(DEVICE(&s->systick[M_REG_NS]), "refclk", s->refclk);
+ /*
+ * Create and map the systick devices. Note that we only connect
+ * refclk if it has been connected to us; otherwise the systick
+ * device gets the wrong answer for clock_has_source(refclk), because
+ * it has an immediate source (the ARMv7M's clock object) but not
+ * an ultimate source, and then it won't correctly auto-select the
+ * CPU clock as its only possible clock source.
+ */
+ if (clock_has_source(s->refclk)) {
+ qdev_connect_clock_in(DEVICE(&s->systick[M_REG_NS]), "refclk",
+ s->refclk);
+ }
qdev_connect_clock_in(DEVICE(&s->systick[M_REG_NS]), "cpuclk", s->cpuclk);
if (!sysbus_realize(SYS_BUS_DEVICE(&s->systick[M_REG_NS]), errp)) {
return;
@@ -438,8 +454,10 @@ static void armv7m_realize(DeviceState *dev, Error **errp)
*/
object_initialize_child(OBJECT(dev), "systick-reg-s",
&s->systick[M_REG_S], TYPE_SYSTICK);
- qdev_connect_clock_in(DEVICE(&s->systick[M_REG_S]), "refclk",
- s->refclk);
+ if (clock_has_source(s->refclk)) {
+ qdev_connect_clock_in(DEVICE(&s->systick[M_REG_S]), "refclk",
+ s->refclk);
+ }
qdev_connect_clock_in(DEVICE(&s->systick[M_REG_S]), "cpuclk",
s->cpuclk);