Patch set updated for coreboot: soc/apollolake: Implement post-raminit romstage and ramstage entry

[Alexandru Gagniuc]

Alexandru Gagniuc ([e-mail]) just uploaded a new patch set to gerrit, which you can find at https://review.coreboot.org/13341

-gerrit

commit af790f746fc5ebb6d24e956404698dbf935f0c74
Author: Andrey Petrov 
Date:   Mon Nov 2 15:18:34 2015 -0800

soc/apollolake: Implement post-raminit romstage and ramstage entry

In order to decompress ramstage, romstage needs significantly larger
    stack than originally set up. To do this, we switch the stack to
    memory right after raminit is done.
    The new stack is allocated in a fashion similar to other soc
    platforms, by reserving it in CBMEM.

Change-Id: I068c283a90f318ce9ee2ad370c3fc2ccb1f8a746
    Signed-off-by: Andrey Petrov 
---
 src/soc/intel/apollolake/Kconfig                | 10 ++++++++
 src/soc/intel/apollolake/include/soc/romstage.h |  3 ++-
 src/soc/intel/apollolake/romstage/entry.inc     | 13 ++++++++++
 src/soc/intel/apollolake/romstage/romstage.c    | 33 ++++++++++++++++++++++---
 4 files changed, 54 insertions(+), 5 deletions(-)

diff --git a/src/soc/intel/apollolake/Kconfig b/src/soc/intel/apollolake/Kconfig
index 8bc7ad4..eb9bd79 100644
--- a/src/soc/intel/apollolake/Kconfig
+++ b/src/soc/intel/apollolake/Kconfig
@@ -72,6 +72,16 @@ config DCACHE_RAM_BOOTBLOCK_STACK_SIZE
      The amount of anticipated stack usage from the bootblock during
      pre-romstage initialization.

+config ROMSTAGE_RAM_STACK_SIZE
+	hex
+	default 0x5000
+	help
+	   The size of the romstage stack after memory is available. Because CAR
+	   space is very crowded, only a very limited part of CAR is available
+	   for stack. More than that is needed to decompress ramstage. This
+	   variable indicates how much RAM to reserve for the stack after
+	   raminit. The stack is automatically switched after romstage_main().
+
 config IFD_BIOS_START
    hex
    default 0x1000
diff --git a/src/soc/intel/apollolake/include/soc/romstage.h b/src/soc/intel/apollolake/include/soc/romstage.h
index f57f26d..eb69558 100644
--- a/src/soc/intel/apollolake/include/soc/romstage.h
+++ b/src/soc/intel/apollolake/include/soc/romstage.h
@@ -15,6 +15,7 @@

#include <arch/cpu.h>

-asmlinkage void romstage_entry(void);
+asmlinkage void *romstage_entry(void);
+asmlinkage void romstage_after_raminit(void);

#endif /* _SOC_APOLLOLAKE_ROMSTAGE_H_ */
diff --git a/src/soc/intel/apollolake/romstage/entry.inc b/src/soc/intel/apollolake/romstage/entry.inc
index b04e17e..8c0670c 100644
--- a/src/soc/intel/apollolake/romstage/entry.inc
+++ b/src/soc/intel/apollolake/romstage/entry.inc
@@ -19,3 +19,16 @@ apollolake_entry:
    mov	esp, (CONFIG_DCACHE_RAM_BASE + 0x4000)

call	romstage_entry
+
+	/*
+	 * eax contains pointer to a region in RAM that we've been given the go
+	 * ahead to use as stack. The old stack is empty at this point, so we
+	 * don't have to relocate anything.
+	 */
+	mov	esp, eax
+
+	/*
+	 * TODO: set up temporary cache for RAM
+	 * We can't tear down CAR yet because romstage resides in CAR.
+	 */
+	call	romstage_after_raminit
diff --git a/src/soc/intel/apollolake/romstage/romstage.c b/src/soc/intel/apollolake/romstage/romstage.c
index 99953fd..6efbdd5 100644
--- a/src/soc/intel/apollolake/romstage/romstage.c
+++ b/src/soc/intel/apollolake/romstage/romstage.c
@@ -12,6 +12,8 @@
  */

#include <arch/io.h>
+#include <cbfs.h>
+#include <cbmem.h>
 #include <console/console.h>
 #include <cpu/x86/msr.h>
 #include <device/pci_def.h>
@@ -50,7 +52,26 @@ static void soc_early_romstage_init(void)
    pci_write_config32(PCI_DEV(0, 13, 0), 0x60, 1<<7);
 }

-asmlinkage void romstage_entry(void)
+static void *alloc_stack_in_ram(void)
+{
+	uint8_t *ram_stack = cbmem_add(CBMEM_ID_ROMSTAGE_RAM_STACK,
+				    CONFIG_ROMSTAGE_RAM_STACK_SIZE);
+
+	/*
+	 * If cbmem fails to give us a memory window, try to get a stack at
+	 * 2 MiB, and hope we can go forward. The 2 MiB address is arbitrary.
+	 */
+	if (ram_stack == NULL) {
+		printk(BIOS_ALERT, "Could not find place for stack\n");
+		return (void *)(2 * MiB);
+	}
+
+	/* The initial stack pointer should point at the top of the region */
+	ram_stack += CONFIG_ROMSTAGE_RAM_STACK_SIZE - sizeof(size_t);
+	return ram_stack;
+}
+
+asmlinkage void* romstage_entry(void)
 {
    /* Be careful. Bootblock might already have initialized the console */
    if (!IS_ENABLED(CONFIG_BOOTBLOCK_CONSOLE)) {
@@ -64,7 +85,11 @@ asmlinkage void romstage_entry(void)

fsp_memory_init();

-	/* This function must not return */
-	while(1)
-		;
+	cbmem_initialize_empty();
+	return alloc_stack_in_ram();
+}
+
+asmlinkage void romstage_after_raminit(void)
+{
+	run_ramstage();
 }