flash: Provide direct flash access with flash_dataptr()

Sometimes it is useful to get access to the flash directly, without using
flash_read(). Add a function to do this.

Since the range checking is done in every function in flash_common,
use the new function to do it for us. That way we get a slight (64 byte)
code size reduction.

BUG=chrome-os-partner:10146
TEST=manual:
build and boot on snow with SPI flash emulation, in U-Boot:

See that the 32KB of flash has been provided correctly.

Change-Id: I6622a24234edaed371dd5b9bf43d1f3974d55e39
Signed-off-by: Simon Glass <sjg@chromium.org>
Reviewed-on: https://gerrit.chromium.org/gerrit/26174

chip/stm32/flash-stm32f100.c

@@ -71,6 +71,7 @@ int flash_physical_read(int offset, int size, char *data)
 	return EC_SUCCESS;
 }
 
+
 static int unlock(int locks)
 {
 	/* unlock CR if needed */

common/flash_common.c

@@ -136,11 +136,23 @@ int flash_get_size(void)
 }
 
 
+char *flash_dataptr(int offset, int size_req, int align, int *sizep)
+{
+	if (offset < 0 || size_req < 0 ||
+			offset + size_req > usable_flash_size ||
+			(offset | size_req) & (align - 1))
+		return NULL;  /* Invalid range */
+	if (sizep)
+		*sizep = usable_flash_size - offset;
+
+	return flash_physical_dataptr(offset);
+}
+
+
 int flash_read(int offset, int size, char *data)
 {
-	if (size < 0 || offset > usable_flash_size ||
-	    offset + size > usable_flash_size)
-		return EC_ERROR_UNKNOWN;  /* Invalid range */
+	if (!flash_dataptr(offset, size, 1, NULL))
+		return EC_ERROR_INVAL;  /* Invalid range */
 
 	return flash_physical_read(offset, size, data);
 }
@@ -148,10 +160,8 @@ int flash_read(int offset, int size, char *data)
 
 int flash_write(int offset, int size, const char *data)
 {
-	if (size < 0 || offset > usable_flash_size ||
-	    offset + size > usable_flash_size ||
-	    (offset | size) & (flash_get_write_block_size() - 1))
-		return EC_ERROR_UNKNOWN;  /* Invalid range */
+	if (!flash_dataptr(offset, size, flash_get_write_block_size(), NULL))
+		return EC_ERROR_INVAL;  /* Invalid range */
 
 	/* TODO (crosbug.com/p/7478) - safety check - don't allow writing to
 	 * the image we're running from */
@@ -162,10 +172,8 @@ int flash_write(int offset, int size, const char *data)
 
 int flash_erase(int offset, int size)
 {
-	if (size < 0 || offset > usable_flash_size ||
-	    offset + size > usable_flash_size ||
-	    (offset | size) & (flash_get_erase_block_size() - 1))
-		return EC_ERROR_UNKNOWN;  /* Invalid range */
+	if (!flash_dataptr(offset, size, flash_get_erase_block_size(), NULL))
+		return EC_ERROR_INVAL;  /* Invalid range */
 
 	/* TODO (crosbug.com/p/7478) - safety check - don't allow erasing the
 	 * image we're running from */
@@ -179,9 +187,7 @@ int flash_protect_until_reboot(int offset, int size)
 	int pbsize = flash_get_protect_block_size();
 	int i;
 
-	if (size < 0 || offset > usable_flash_size ||
-	    offset + size > usable_flash_size ||
-	    (offset | size) & (pbsize - 1))
+	if (!flash_dataptr(offset, size, pbsize, NULL))
 		return EC_ERROR_INVAL;  /* Invalid range */
 
 	/* Convert offset and size to blocks */
@@ -200,9 +206,7 @@ int flash_set_protect(int offset, int size, int enable)
 	int pbsize = flash_get_protect_block_size();
 	int rv, i;
 
-	if (size < 0 || offset > usable_flash_size ||
-	    offset + size > usable_flash_size ||
-	    (offset | size) & (pbsize - 1))
+	if (!flash_dataptr(offset, size, pbsize, NULL))
 		return EC_ERROR_INVAL;  /* Invalid range */
 
 	/* Fail if write protect block is already locked */
@@ -288,9 +292,7 @@ int flash_get_protect(int offset, int size)
 	uint8_t minflags = 0xff;
 	int i;
 
-	if (size < 0 || offset > usable_flash_size ||
-	    offset + size > usable_flash_size ||
-	    (offset | size) & (pbsize - 1))
+	if (!flash_dataptr(offset, size, pbsize, NULL))
 		return 0;  /* Invalid range; assume nothing protected */
 
 	/* Convert offset and size to blocks */

include/flash.h

@@ -24,6 +24,22 @@ int flash_get_protect_block_size(void);
 /* Return the physical size of flash in bytes */
 int flash_physical_size(void);
 
+/**
+ * Get the physical memory address of a flash offset
+ *
+ * This is used for direct flash access. We assume that the flash is
+ * contiguous from this start address through to the end of the usable
+ * flash.
+ *
+ * @param offset	Flash offset to get address of
+ * @param dataptrp	Returns pointer to memory address of flash offset
+ * @return pointer to flash memory offset, if ok, else NULL
+ */
+static inline char *flash_physical_dataptr(int offset)
+{
+	return (char *)offset;
+}
+
 /* Read <size> bytes of data from offset <offset> into <data>. */
 int flash_physical_read(int offset, int size, char *data);
 
@@ -50,6 +66,27 @@ int flash_pre_init(void);
  * smaller than the actual flash size, */
 int flash_get_size(void);
 
+/**
+ * Get the physical memory address of a flash offset
+ *
+ * This is used for direct flash access. We assume that the flash is
+ * contiguous from this start address through to the end of the usable
+ * flash.
+ *
+ * This function returns NULL if offset + size_req extends beyond the end
+ * of flash, or if either size_req or offset are not aligned to 'align'.
+ *
+ * @param offset	Flash offset to get address of
+ * @param size_req	Number of bytes requested
+ * @param align		Ensure offset and size_req are aligned to given
+ *			power of two.
+ * @param sizep		If not NULL, returns amount of flash available at
+ *			this memory addr, unless function fails, iwc it is
+ *			unset.
+ * @return pointer to flash, or NULL on error
+ */
+char *flash_dataptr(int offset, int size_req, int align, int *sizep);
+
 /* Reads <size> bytes of data from offset <offset> into <data>. */
 int flash_read(int offset, int size, char *data);