drivers/firmware: const-ify DMI API and internals

Three main sets of changes:

1) dmi_get_system_info() return value should have been marked const,
   since callers should not be changing that data.

2) const-ify DMI internals, since DMI firmware tables should,
   whenever possible, be marked const to ensure we never ever write to
   that data area.

3) const-ify DMI API, to enable marking tables const where possible
   in low-level drivers.

And if we're really lucky, this might enable some additional
optimizations on the part of the compiler.

The bulk of the changes are #2 and #3, which are interrelated.  #1 could
have been a separate patch, but it was so small compared to the others,
it was easier to roll it into this changeset.

Signed-off-by: Jeff Garzik <jgarzik@redhat.com>

1 files changed, 31 insertions, 26 deletions

diff --git a/drivers/firmware/dmi_scan.c b/drivers/firmware/dmi_scan.c
index f7318b3..0cdadea 100644
--- a/drivers/firmware/dmi_scan.c
+++ b/drivers/firmware/dmi_scan.c
@@ -8,9 +8,9 @@
 #include <linux/slab.h>
 #include <asm/dmi.h>
 
-static char * __init dmi_string(struct dmi_header *dm, u8 s)
+static char * __init dmi_string(const struct dmi_header *dm, u8 s)
 {
-	u8 *bp = ((u8 *) dm) + dm->length;
+	const u8 *bp = ((u8 *) dm) + dm->length;
 	char *str = "";
 
 	if (s) {
@@ -37,7 +37,7 @@ static char * __init dmi_string(struct dmi_header *dm, u8 s)
  *	pointing to completely the wrong place for example
  */
 static int __init dmi_table(u32 base, int len, int num,
-			    void (*decode)(struct dmi_header *))
+			    void (*decode)(const struct dmi_header *))
 {
 	u8 *buf, *data;
 	int i = 0;
@@ -53,7 +53,8 @@ static int __init dmi_table(u32 base, int len, int num,
 	 *	OR we run off the end of the table (also happens)
 	 */
 	while ((i < num) && (data - buf + sizeof(struct dmi_header)) <= len) {
-		struct dmi_header *dm = (struct dmi_header *)data;
+		const struct dmi_header *dm = (const struct dmi_header *)data;
+
 		/*
 		 *  We want to know the total length (formated area and strings)
 		 *  before decoding to make sure we won't run off the table in
@@ -71,7 +72,7 @@ static int __init dmi_table(u32 base, int len, int num,
 	return 0;
 }
 
-static int __init dmi_checksum(u8 *buf)
+static int __init dmi_checksum(const u8 *buf)
 {
 	u8 sum = 0;
 	int a;
@@ -89,9 +90,10 @@ int dmi_available;
 /*
  *	Save a DMI string
  */
-static void __init dmi_save_ident(struct dmi_header *dm, int slot, int string)
+static void __init dmi_save_ident(const struct dmi_header *dm, int slot, int string)
 {
-	char *p, *d = (char*) dm;
+	const char *d = (const char*) dm;
+	char *p;
 
 	if (dmi_ident[slot])
 		return;
@@ -103,9 +105,9 @@ static void __init dmi_save_ident(struct dmi_header *dm, int slot, int string)
 	dmi_ident[slot] = p;
 }
 
-static void __init dmi_save_uuid(struct dmi_header *dm, int slot, int index)
+static void __init dmi_save_uuid(const struct dmi_header *dm, int slot, int index)
 {
-	u8 *d = (u8*) dm + index;
+	const u8 *d = (u8*) dm + index;
 	char *s;
 	int is_ff = 1, is_00 = 1, i;
 
@@ -132,9 +134,9 @@ static void __init dmi_save_uuid(struct dmi_header *dm, int slot, int index)
         dmi_ident[slot] = s;
 }
 
-static void __init dmi_save_type(struct dmi_header *dm, int slot, int index)
+static void __init dmi_save_type(const struct dmi_header *dm, int slot, int index)
 {
-	u8 *d = (u8*) dm + index;
+	const u8 *d = (u8*) dm + index;
 	char *s;
 
 	if (dmi_ident[slot])
@@ -148,13 +150,13 @@ static void __init dmi_save_type(struct dmi_header *dm, int slot, int index)
 	dmi_ident[slot] = s;
 }
 
-static void __init dmi_save_devices(struct dmi_header *dm)
+static void __init dmi_save_devices(const struct dmi_header *dm)
 {
 	int i, count = (dm->length - sizeof(struct dmi_header)) / 2;
 	struct dmi_device *dev;
 
 	for (i = 0; i < count; i++) {
-		char *d = (char *)(dm + 1) + (i * 2);
+		const char *d = (char *)(dm + 1) + (i * 2);
 
 		/* Skip disabled device */
 		if ((*d & 0x80) == 0)
@@ -173,7 +175,7 @@ static void __init dmi_save_devices(struct dmi_header *dm)
 	}
 }
 
-static void __init dmi_save_oem_strings_devices(struct dmi_header *dm)
+static void __init dmi_save_oem_strings_devices(const struct dmi_header *dm)
 {
 	int i, count = *(u8 *)(dm + 1);
 	struct dmi_device *dev;
@@ -194,7 +196,7 @@ static void __init dmi_save_oem_strings_devices(struct dmi_header *dm)
 	}
 }
 
-static void __init dmi_save_ipmi_device(struct dmi_header *dm)
+static void __init dmi_save_ipmi_device(const struct dmi_header *dm)
 {
 	struct dmi_device *dev;
 	void * data;
@@ -225,7 +227,7 @@ static void __init dmi_save_ipmi_device(struct dmi_header *dm)
  *	and machine entries. For 2.5 we should pull the smbus controller info
  *	out of here.
  */
-static void __init dmi_decode(struct dmi_header *dm)
+static void __init dmi_decode(const struct dmi_header *dm)
 {
 	switch(dm->type) {
 	case 0:		/* BIOS Information */
@@ -265,9 +267,10 @@ static void __init dmi_decode(struct dmi_header *dm)
 	}
 }
 
-static int __init dmi_present(char __iomem *p)
+static int __init dmi_present(const char __iomem *p)
 {
 	u8 buf[15];
+
 	memcpy_fromio(buf, p, 15);
 	if ((memcmp(buf, "_DMI_", 5) == 0) && dmi_checksum(buf)) {
 		u16 num = (buf[13] << 8) | buf[12];
@@ -348,10 +351,10 @@ void __init dmi_scan_machine(void)
  *	returns non zero or we hit the end. Callback function is called for
  *	each successful match. Returns the number of matches.
  */
-int dmi_check_system(struct dmi_system_id *list)
+int dmi_check_system(const struct dmi_system_id *list)
 {
 	int i, count = 0;
-	struct dmi_system_id *d = list;
+	const struct dmi_system_id *d = list;
 
 	while (d->ident) {
 		for (i = 0; i < ARRAY_SIZE(d->matches); i++) {
@@ -380,7 +383,7 @@ EXPORT_SYMBOL(dmi_check_system);
  *	Returns one DMI data value, can be used to perform
  *	complex DMI data checks.
  */
-char *dmi_get_system_info(int field)
+const char *dmi_get_system_info(int field)
 {
 	return dmi_ident[field];
 }
@@ -391,7 +394,7 @@ EXPORT_SYMBOL(dmi_get_system_info);
  *	dmi_name_in_vendors - Check if string is anywhere in the DMI vendor information.
  *	@str: 	Case sensitive Name
  */
-int dmi_name_in_vendors(char *str)
+int dmi_name_in_vendors(const char *str)
 {
 	static int fields[] = { DMI_BIOS_VENDOR, DMI_BIOS_VERSION, DMI_SYS_VENDOR,
 				DMI_PRODUCT_NAME, DMI_PRODUCT_VERSION, DMI_BOARD_VENDOR,
@@ -418,13 +421,15 @@ EXPORT_SYMBOL(dmi_name_in_vendors);
  *	A new search is initiated by passing %NULL as the @from argument.
  *	If @from is not %NULL, searches continue from next device.
  */
-struct dmi_device * dmi_find_device(int type, const char *name,
-				    struct dmi_device *from)
+const struct dmi_device * dmi_find_device(int type, const char *name,
+				    const struct dmi_device *from)
 {
-	struct list_head *d, *head = from ? &from->list : &dmi_devices;
+	const struct list_head *head = from ? &from->list : &dmi_devices;
+	struct list_head *d;
 
 	for(d = head->next; d != &dmi_devices; d = d->next) {
-		struct dmi_device *dev = list_entry(d, struct dmi_device, list);
+		const struct dmi_device *dev =
+			list_entry(d, struct dmi_device, list);
 
 		if (((type == DMI_DEV_TYPE_ANY) || (dev->type == type)) &&
 		    ((name == NULL) || (strcmp(dev->name, name) == 0)))
@@ -444,7 +449,7 @@ EXPORT_SYMBOL(dmi_find_device);
 int dmi_get_year(int field)
 {
 	int year;
-	char *s = dmi_get_system_info(field);
+	const char *s = dmi_get_system_info(field);
 
 	if (!s)
 		return -1;