x86: mp: Allow running functions on multiple CPUs

Add a way to run a function on a selection of CPUs. This supports either
a single CPU, all CPUs, just the main CPU or just the 'APs', in Intel
terminology.

It works by writing into a mailbox and then waiting for the CPUs to notice
it, take action and indicate they are done.

When SMP is not yet enabled, this just calls the function on the main CPU.

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

1 files changed, 33 insertions, 0 deletions

diff --git a/arch/x86/include/asm/mp.h b/arch/x86/include/asm/mp.h
index 41b1575f4b..eb49e690f2 100644
--- a/arch/x86/include/asm/mp.h
+++ b/arch/x86/include/asm/mp.h
@@ -86,4 +86,37 @@ int mp_init(void);
 /* Set up additional CPUs */
 int x86_mp_init(void);
 
+/**
+ * mp_run_func() - Function to call on the AP
+ *
+ * @arg: Argument to pass
+ */
+typedef void (*mp_run_func)(void *arg);
+
+#if defined(CONFIG_SMP) && !CONFIG_IS_ENABLED(X86_64)
+/**
+ * mp_run_on_cpus() - Run a function on one or all CPUs
+ *
+ * This does not return until all CPUs have completed the work
+ *
+ * Running on anything other than the boot CPU is only supported if
+ * CONFIG_SMP_AP_WORK is enabled
+ *
+ * @cpu_select: CPU to run on (its dev->req_seq value), or MP_SELECT_ALL for
+ *	all, or MP_SELECT_BSP for BSP
+ * @func: Function to run
+ * @arg: Argument to pass to the function
+ * @return 0 on success, -ve on error
+ */
+int mp_run_on_cpus(int cpu_select, mp_run_func func, void *arg);
+#else
+static inline int mp_run_on_cpus(int cpu_select, mp_run_func func, void *arg)
+{
+	/* There is only one CPU, so just call the function here */
+	func(arg);
+
+	return 0;
+}
+#endif
+
 #endif /* _X86_MP_H_ */