postcar_loader: Support LATE_CBMEM_INIT boards

Create postcar_frame object without placing stack in CBMEM.
This way same cache_as_ram.inc code can be used unmodified.

Change-Id: Ic5ed404ce268ee881e9893dd434534231aa2bc88
Signed-off-by: Kyösti Mälkki <kyosti.malkki@gmail.com>
Reviewed-on: https://review.coreboot.org/17700
Tested-by: build bot (Jenkins)
Reviewed-by: Aaron Durbin <adurbin@chromium.org>

2 files changed, 26 insertions, 10 deletions

diff --git a/src/arch/x86/include/arch/cpu.h b/src/arch/x86/include/arch/cpu.h
index a923d8e48e..9c94ab1e8e 100644
--- a/src/arch/x86/include/arch/cpu.h
+++ b/src/arch/x86/include/arch/cpu.h
@@ -271,6 +271,11 @@ struct postcar_frame {
 int postcar_frame_init(struct postcar_frame *pcf, size_t stack_size);
 
 /*
+ * Initialize postcar_frame object with a fixed stacktop in low memory.
+ */
+void postcar_frame_init_lowmem(struct postcar_frame *pcf);
+
+/*
  * Add variable MTRR covering the provided range with MTRR type.
  */
 void postcar_frame_add_mtrr(struct postcar_frame *pcf,
diff --git a/src/arch/x86/postcar_loader.c b/src/arch/x86/postcar_loader.c
index 23f33d556d..287a0d807b 100644
--- a/src/arch/x86/postcar_loader.c
+++ b/src/arch/x86/postcar_loader.c
@@ -33,13 +33,20 @@ static inline void stack_push(struct postcar_frame *pcf, uint32_t val)
 	*ptr = val;
 }
 
-int postcar_frame_init(struct postcar_frame *pcf, size_t stack_size)
+static void postcar_frame_prepare(struct postcar_frame *pcf)
 {
-	void *stack;
 	msr_t msr;
-
 	msr = rdmsr(MTRR_CAP_MSR);
 
+	pcf->upper_mask = (1 << (cpu_phys_address_size() - 32)) - 1;
+	pcf->max_var_mttrs = msr.lo & MTRR_CAP_VCNT;
+	pcf->num_var_mttrs = 0;
+}
+
+int postcar_frame_init(struct postcar_frame *pcf, size_t stack_size)
+{
+	void *stack;
+
 	stack = cbmem_add(CBMEM_ID_ROMSTAGE_RAM_STACK, stack_size);
 	if (stack == NULL) {
 		printk(BIOS_ERR, "Couldn't add %zd byte stack in cbmem.\n",
@@ -47,18 +54,22 @@ int postcar_frame_init(struct postcar_frame *pcf, size_t stack_size)
 		return -1;
 	}
 
+	postcar_frame_prepare(pcf);
 	pcf->stack = (uintptr_t)stack;
 	pcf->stack += stack_size;
-
-	pcf->upper_mask = (1 << (cpu_phys_address_size() - 32)) - 1;
-
-	pcf->max_var_mttrs = msr.lo & MTRR_CAP_VCNT;
-
-	pcf->num_var_mttrs = 0;
-
 	return 0;
 }
 
+/*
+ * For use with LATE_CBMEM_INIT boards only, with a fixed stacktop in
+ * low memory.
+ */
+void postcar_frame_init_lowmem(struct postcar_frame *pcf)
+{
+	postcar_frame_prepare(pcf);
+	pcf->stack = CONFIG_RAMTOP;
+}
+
 void postcar_frame_add_mtrr(struct postcar_frame *pcf,
 				uintptr_t addr, size_t size, int type)
 {