fw_setenv: lock the flash only if it was locked before

With current implementation of fw_setenv, it is always locks u-boot-env
region if lock interface is implemented for such mtd device. You can
not control lock of this region with fw_setenv, there is no option for
it in config or in application itself. Because of this situation may
happen problems like in this thread on xilinx forum:
https://forums.xilinx.com/t5/Embedded-Linux/Flash-be-locked-after-use-fw-setenv-from-user-space
/td-p/1027851

A short summary of that link is: some person has issue with some spi
chip which has lock interface but doesn't locks properly which leads to
lock of whole flash memory on lock of u-boot-env region. As resulted
solution hack was added into spi-nor.c driver for this chip with lock
disablement.

Instead fix this problem by adding logic to fw_setenv only lock the
flash if it was already locked when we attempted to use it.

Signed-off-by: Ivan Mikhaylov <fr0st61te@gmail.com>

diff --git a/tools/env/fw_env.c b/tools/env/fw_env.c
index c6378ec..3ab1ae6 100644 (file)
--- a/tools/env/fw_env.c
+++ b/tools/env/fw_env.c
@@ -995,6 +995,7 @@ static int flash_write_buf(int dev, int fd, void *buf, size_t count)
                                   of the data */
        loff_t blockstart;      /* running start of the current block -
                                   MEMGETBADBLOCK needs 64 bits */
+       int was_locked;         /* flash lock flag */
        int rc;
 
        /*
@@ -1080,6 +1081,12 @@ static int flash_write_buf(int dev, int fd, void *buf, size_t count)
        }
 
        erase.length = erasesize;
+       if (DEVTYPE(dev) != MTD_ABSENT) {
+               was_locked = ioctl(fd, MEMISLOCKED, &erase);
+               /* treat any errors as unlocked flash */
+               if (was_locked < 0)
+                       was_locked = 0;
+       }
 
        /* This only runs once on NOR flash and SPI-dataflash */
        while (processed < write_total) {
@@ -1099,7 +1106,8 @@ static int flash_write_buf(int dev, int fd, void *buf, size_t count)
 
                if (DEVTYPE(dev) != MTD_ABSENT) {
                        erase.start = blockstart;
-                       ioctl(fd, MEMUNLOCK, &erase);
+                       if (was_locked)
+                               ioctl(fd, MEMUNLOCK, &erase);
                        /* These do not need an explicit erase cycle */
                        if (DEVTYPE(dev) != MTD_DATAFLASH)
                                if (ioctl(fd, MEMERASE, &erase) != 0) {
@@ -1127,8 +1135,10 @@ static int flash_write_buf(int dev, int fd, void *buf, size_t count)
                        return -1;
                }
 
-               if (DEVTYPE(dev) != MTD_ABSENT)
-                       ioctl(fd, MEMLOCK, &erase);
+               if (DEVTYPE(dev) != MTD_ABSENT) {
+                       if (was_locked)
+                               ioctl(fd, MEMLOCK, &erase);
+               }
 
                processed += erasesize;
                block_seek = 0;
@@ -1149,7 +1159,9 @@ static int flash_flag_obsolete(int dev, int fd, off_t offset)
        int rc;
        struct erase_info_user erase;
        char tmp = ENV_REDUND_OBSOLETE;
+       int was_locked; /* flash lock flag */
 
+       was_locked = ioctl(fd, MEMISLOCKED, &erase);
        erase.start = DEVOFFSET(dev);
        erase.length = DEVESIZE(dev);
        /* This relies on the fact, that ENV_REDUND_OBSOLETE == 0 */
@@ -1159,9 +1171,11 @@ static int flash_flag_obsolete(int dev, int fd, off_t offset)
                        DEVNAME(dev));
                return rc;
        }
-       ioctl(fd, MEMUNLOCK, &erase);
+       if (was_locked)
+               ioctl(fd, MEMUNLOCK, &erase);
        rc = write(fd, &tmp, sizeof(tmp));
-       ioctl(fd, MEMLOCK, &erase);
+       if (was_locked)
+               ioctl(fd, MEMLOCK, &erase);
        if (rc < 0)
                perror("Could not set obsolete flag");