dm: Add a new CPU init function which can use driver model

Since driver model is set up after arch_cpu_init(), that function cannot
use drivers. Add a new arch_cpu_init_dm() function which is called
immediately after driver model is ready, and can reference devices.

This can be used to probe essential devices for the CPU.

Signed-off-by: Simon Glass <sjg@chromium.org>
Reviewed-by: Bin Meng <bmeng.cn@gmail.com>

common/board_f.c

@@ -815,6 +815,11 @@ __weak int reserve_arch(void)
 	return 0;
 }
 
+__weak int arch_cpu_init_dm(void)
+{
+	return 0;
+}
+
 static init_fnc_t init_sequence_f[] = {
 #ifdef CONFIG_SANDBOX
 	setup_ram_buf,
@@ -835,6 +840,7 @@ static init_fnc_t init_sequence_f[] = {
 	fdtdec_check_fdt,
 #endif
 	initf_dm,
+	arch_cpu_init_dm,
 #if defined(CONFIG_BOARD_EARLY_INIT_F)
 	board_early_init_f,
 #endif

include/common.h

@@ -253,6 +253,17 @@ int update_flash_size(int flash_size);
 int arch_early_init_r(void);
 
 /**
+ * arch_cpu_init_dm() - init CPU after driver model is available
+ *
+ * This is called immediately after driver model is available before
+ * relocation. This is similar to arch_cpu_init() but is able to reference
+ * devices
+ *
+ * @return 0 if OK, -ve on error
+ */
+int arch_cpu_init_dm(void);
+
+/**
  * Reserve all necessary stacks
  *
  * This is used in generic board init sequence in common/board_f.c. Each