[RFT PATCH 2/2] mtd: cfi-flash: call ctrlc() during CFI reads

[Ahmad Fatoum <a.fatoum@pengutronix.de>]

Memory mapped flash access can be quite slow on older processors. For
writing and erasing, we already call resched() indirectly to feed the
watchdog, so let's do this when reading as well. This fixes an issue
of short running watchdogs triggering on PowerPC, because kernel boot
takes too long.

Signed-off-by: Ahmad Fatoum <a.fatoum@pengutronix.de>
---
 drivers/mtd/nor/cfi_flash.c | 12 ++++++++++--
 1 file changed, 10 insertions(+), 2 deletions(-)

diff --git a/drivers/mtd/nor/cfi_flash.c b/drivers/mtd/nor/cfi_flash.c
index f1555a72a42e..10542c710118 100644
--- a/drivers/mtd/nor/cfi_flash.c
+++ b/drivers/mtd/nor/cfi_flash.c
@@ -25,7 +25,9 @@
 #include <io.h>
 #include <errno.h>
 #include <progress.h>
+#include <string.h>
 #include <linux/err.h>
+#include <linux/sizes.h>
 #include <asm/unaligned.h>
 #include <linux/mtd/concat.h>
 #include "cfi_flash.h"
@@ -891,10 +893,16 @@ static int cfi_mtd_read(struct mtd_info *mtd, loff_t from, size_t len,
 		size_t *retlen, u8 *buf)
 {
 	struct flash_info *info = container_of(mtd, struct flash_info, mtd);
+	const void *src = info->base + from;
+	size_t i;
+
+	for (i = 0; i < len; i = size_add(i, SZ_1M)) {
+		buf = mempcpy(buf, src + i, min_t(size_t, len, SZ_1M));
+		if (ctrlc())
+			return -EINTR;
+	}
 
-	memcpy(buf, info->base + from, len);
 	*retlen = len;
-
 	return 0;
 }
 
-- 
2.39.2