lib: provide clearer devicetree semantics

The devicetree data structures have been available in more than just
ramstage and romstage. In order to provide clearer and consistent
semantics two new macros are provided:

1. DEVTREE_EARLY which is true when !ENV_RAMSTAGE
2. DEVTREE_CONST as a replacment for ROMSTAGE_CONST

The ROMSTAGE_CONST attribute is used in the source code to mark
the devicetree data structures as const in early stages even though
it's not just romstage. Therefore, rename the attribute to
DEVTREE_CONST as that's the actual usage. The only place where the
usage was not devicetree related is console_loglevel, but the same
name was used for consistency. Any stage that is not ramstage has
the const C attribute applied when DEVTREE_CONST is used.

Change-Id: Ibd51c2628dc8f68e0896974f7e4e7c8588d333ed
Signed-off-by: Aaron Durbin <adurbin@chromium.org>
Reviewed-on: https://review.coreboot.org/19333
Tested-by: build bot (Jenkins)
Reviewed-by: Philippe Mathieu-Daudé <philippe.mathieu.daude@gmail.com>
Reviewed-by: Furquan Shaikh <furquan@google.com>

3 files changed, 29 insertions, 20 deletions

diff --git a/src/include/device/device.h b/src/include/device/device.h
index bb0d0ca8b8..7b4fce36ea 100644
--- a/src/include/device/device.h
+++ b/src/include/device/device.h
@@ -84,9 +84,9 @@ static inline void device_noop(struct device *dev) {}
 
 struct bus {
 
-	ROMSTAGE_CONST struct device *dev;	/* This bridge device */
-	ROMSTAGE_CONST struct device *children;	/* devices behind this bridge */
-	ROMSTAGE_CONST struct bus *next;    /* The next bridge on this device */
+	DEVTREE_CONST struct device *dev;	/* This bridge device */
+	DEVTREE_CONST struct device *children;	/* devices behind this bridge */
+	DEVTREE_CONST struct bus *next;    /* The next bridge on this device */
 	unsigned int	bridge_ctrl;	/* Bridge control register */
 	uint16_t	bridge_cmd;		/* Bridge command register */
 	unsigned char	link_num;	/* The index of this link */
@@ -113,12 +113,12 @@ struct pci_irq_info {
 };
 
 struct device {
-	ROMSTAGE_CONST struct bus *bus;	/* bus this device is on, for bridge
+	DEVTREE_CONST struct bus *bus;	/* bus this device is on, for bridge
 					 * devices, it is the up stream bus */
 
-	ROMSTAGE_CONST struct device *sibling;	/* next device on this bus */
+	DEVTREE_CONST struct device *sibling;	/* next device on this bus */
 
-	ROMSTAGE_CONST struct device *next;	/* chain of all devices */
+	DEVTREE_CONST struct device *next;	/* chain of all devices */
 
 	struct device_path path;
 	unsigned int	vendor;
@@ -134,26 +134,26 @@ struct device {
 	u8 command;
 
 	/* Base registers for this device. I/O, MEM and Expansion ROM */
-	ROMSTAGE_CONST struct resource *resource_list;
+	DEVTREE_CONST struct resource *resource_list;
 
 	/* links are (downstream) buses attached to the device, usually a leaf
 	 * device with no children has 0 buses attached and a bridge has 1 bus
 	 */
-	ROMSTAGE_CONST struct bus *link_list;
+	DEVTREE_CONST struct bus *link_list;
 
 	struct device_operations *ops;
-#ifndef __PRE_RAM__
+#if !DEVTREE_EARLY
 	struct chip_operations *chip_ops;
 	const char *name;
 #endif
-	ROMSTAGE_CONST void *chip_info;
+	DEVTREE_CONST void *chip_info;
 };
 
 /**
  * This is the root of the device tree. The device tree is defined in the
  * static.c file and is generated by the config tool at compile time.
  */
-extern ROMSTAGE_CONST struct device	dev_root;
+extern DEVTREE_CONST struct device	dev_root;
 
 #ifndef __SIMPLE_DEVICE__
 
@@ -272,13 +272,13 @@ u32 find_pci_tolm(struct bus *bus);
 
 #else /* vv __SIMPLE_DEVICE__ vv */
 
-ROMSTAGE_CONST struct device *dev_find_slot(unsigned int bus,
+DEVTREE_CONST struct device *dev_find_slot(unsigned int bus,
 						unsigned int devfn);
-ROMSTAGE_CONST struct device *dev_find_next_pci_device(
-				ROMSTAGE_CONST struct device *previous_dev);
-ROMSTAGE_CONST struct device *dev_find_slot_on_smbus(unsigned int bus,
+DEVTREE_CONST struct device *dev_find_next_pci_device(
+				DEVTREE_CONST struct device *previous_dev);
+DEVTREE_CONST struct device *dev_find_slot_on_smbus(unsigned int bus,
 							unsigned int addr);
-ROMSTAGE_CONST struct device *dev_find_slot_pnp(u16 port, u16 device);
+DEVTREE_CONST struct device *dev_find_slot_pnp(u16 port, u16 device);
 
 #endif
 
diff --git a/src/include/device/resource.h b/src/include/device/resource.h
index d794fb21e7..eefaf96e28 100644
--- a/src/include/device/resource.h
+++ b/src/include/device/resource.h
@@ -42,7 +42,7 @@ struct resource {
 	resource_t base;	/* Base address of the resource */
 	resource_t size;	/* Size of the resource */
 	resource_t limit;	/* Largest valid value base + size -1 */
-	ROMSTAGE_CONST struct resource *next;	/* Next resource in the list */
+	DEVTREE_CONST struct resource *next;	/* Next resource in the list */
 	unsigned long flags;	/* Descriptions of the kind of resource */
 	unsigned long index;	/* Bus specific per device resource id */
 	unsigned char align;	/* Required alignment (log 2) of the resource */
diff --git a/src/include/stddef.h b/src/include/stddef.h
index d0308d2580..af63196697 100644
--- a/src/include/stddef.h
+++ b/src/include/stddef.h
@@ -2,6 +2,7 @@
 #define STDDEF_H
 
 #include <commonlib/helpers.h>
+#include <rules.h>
 
 typedef long ptrdiff_t;
 #ifndef __SIZE_TYPE__
@@ -21,10 +22,18 @@ typedef unsigned int wint_t;
 
 #define NULL ((void *)0)
 
-#ifdef __PRE_RAM__
-#define ROMSTAGE_CONST const
+/* The devicetree data structures are only mutable in ramstage. All other
+   stages have a constant devicetree. */
+#if !ENV_RAMSTAGE
+#define DEVTREE_EARLY 1
 #else
-#define ROMSTAGE_CONST
+#define DEVTREE_EARLY 0
+#endif
+
+#if DEVTREE_EARLY
+#define DEVTREE_CONST const
+#else
+#define DEVTREE_CONST
 #endif
 
 /* Work around non-writable data segment in execute-in-place romstage on x86. */