mtd: spi-nor: add read loop

mtdblock and ubi do not handle the situation when read returns less data
than requested. Loop in spi-nor until buffer is filled or an error is
returned.

Signed-off-by: Michal Suchanek <hramrach@gmail.com>
Signed-off-by: Brian Norris <computersforpeace@gmail.com>
Tested-by Cyrille Pitchen <cyrille.pitchen@atmel.com>
Acked-by: Michal Suchanek <hramrach@gmail.com>
Tested-by: Michal Suchanek <hramrach@gmail.com>

1 files changed, 19 insertions, 6 deletions

diff --git a/drivers/mtd/spi-nor/spi-nor.c b/drivers/mtd/spi-nor/spi-nor.c
index fe55b48be5b3..a63922ed6385 100644
--- a/drivers/mtd/spi-nor/spi-nor.c
+++ b/drivers/mtd/spi-nor/spi-nor.c
@@ -1031,14 +1031,27 @@ static int spi_nor_read(struct mtd_info *mtd, loff_t from, size_t len,
         if (ret)
                 return ret;
 
-        ret = nor->read(nor, from, len, buf);
+        while (len) {
+                ret = nor->read(nor, from, len, buf);
+                if (ret == 0) {
+                        /* We shouldn't see 0-length reads */
+                        ret = -EIO;
+                        goto read_err;
+                }
+                if (ret < 0)
+                        goto read_err;
 
-        spi_nor_unlock_and_unprep(nor, SPI_NOR_OPS_READ);
-        if (ret < 0)
-                return ret;
+                WARN_ON(ret > len);
+                *retlen += ret;
+                buf += ret;
+                from += ret;
+                len -= ret;
+        }
+        ret = 0;
 
-        *retlen += ret;
-        return 0;
+read_err:
+        spi_nor_unlock_and_unprep(nor, SPI_NOR_OPS_READ);
+        return ret;
 }
 
 static int sst_write(struct mtd_info *mtd, loff_t to, size_t len,