[PATCH v4 14/25] x86: mp: Park CPUs before running the OS

[Simon Glass <sjg@chromium.org>]

With the new MP features the CPUs are no-longer parked when the OS is run.
Fix this by calling a special function to park them, just before the OS is
started.

Signed-off-by: Simon Glass <sjg@chromium.org>
Reviewed-by: Wolfgang Wallner <wolfgang.wallner@br-automation.com>
---

(no changes since v3)

Changes in v3:
- Update the comment for mp_park_aps()

 arch/x86/cpu/cpu.c        |  5 +++++
 arch/x86/cpu/mp_init.c    | 18 ++++++++++++++++++
 arch/x86/include/asm/mp.h | 17 +++++++++++++++++
 3 files changed, 40 insertions(+)

diff --git a/arch/x86/cpu/cpu.c b/arch/x86/cpu/cpu.c
index d0720fb7fb..baa7dae172 100644
--- a/arch/x86/cpu/cpu.c
+++ b/arch/x86/cpu/cpu.c
@@ -66,6 +66,11 @@ static const char *const x86_vendor_name[] = {
 
 int __weak x86_cleanup_before_linux(void)
 {
+	int ret;
+
+	ret = mp_park_aps();
+	if (ret)
+		return log_msg_ret("park", ret);
 	bootstage_stash((void *)CONFIG_BOOTSTAGE_STASH_ADDR,
 			CONFIG_BOOTSTAGE_STASH_SIZE);
 
diff --git a/arch/x86/cpu/mp_init.c b/arch/x86/cpu/mp_init.c
index dd6d6bfab7..721b729d92 100644
--- a/arch/x86/cpu/mp_init.c
+++ b/arch/x86/cpu/mp_init.c
@@ -668,6 +668,24 @@ int mp_run_on_cpus(int cpu_select, mp_run_func func, void *arg)
 	return 0;
 }
 
+static void park_this_cpu(void *unused)
+{
+	stop_this_cpu();
+}
+
+int mp_park_aps(void)
+{
+	unsigned long start;
+	int ret;
+
+	start = get_timer(0);
+	ret = mp_run_on_cpus(MP_SELECT_APS, park_this_cpu, NULL);
+	if (ret)
+		return ret;
+
+	return get_timer(start);
+}
+
 int mp_init(void)
 {
 	int num_aps, num_cpus;
diff --git a/arch/x86/include/asm/mp.h b/arch/x86/include/asm/mp.h
index eb49e690f2..93b1786b66 100644
--- a/arch/x86/include/asm/mp.h
+++ b/arch/x86/include/asm/mp.h
@@ -109,6 +109,15 @@ typedef void (*mp_run_func)(void *arg);
  * @return 0 on success, -ve on error
  */
 int mp_run_on_cpus(int cpu_select, mp_run_func func, void *arg);
+
+/**
+ * mp_park_aps() - Park the APs ready for the OS
+ *
+ * This halts all CPUs except the main one, ready for the OS to use them
+ *
+ * @return time taken to park the APs on success (in microseconds), -ve on error
+ */
+int mp_park_aps(void);
 #else
 static inline int mp_run_on_cpus(int cpu_select, mp_run_func func, void *arg)
 {
@@ -117,6 +126,14 @@ static inline int mp_run_on_cpus(int cpu_select, mp_run_func func, void *arg)
 
 	return 0;
 }
+
+static inline int mp_park_aps(void)
+{
+	/* No APs to park */
+
+	return 0;
+}
+
 #endif
 
 #endif /* _X86_MP_H_ */
-- 
2.27.0.383.g050319c2ae-goog