mtd: fsl-quadspi: Fix module unbound

When removing the fsl-quadspi module and running 'cat /proc/mtd' afterwards,
we see garbage data like:

$ rmmod  fsl-quadspi
$ cat /proc/mtd
dev:    size   erasesize  name
mtd0: 00000000 00000000 "(null)"
mtd0: 00000000 00000000 "(null)"
mtd0: 00000000 00000000 "(null)"
...
mtd0: a22296c6c756e28 00000000 "(null)"
mtd0: a22296c6c756e28 3064746d "(null)"

If we continue doing multiple module load/unload operations, then it will also
lead to a kernel crash.

The reason for this is due to the wrong mtd index used in
mtd_device_unregister() in the remove function.

We need to keep the mtd unregister index aligned with the one used in the probe
function, which means we need to take into account the 'has_second_chip'
property. By doing so we can guarantee that the mtd index is the same in the
registration and unregistration functions.

With this patch applied we can load/unload the fsl-quadspi driver several times
and it will result in no crash.

Signed-off-by: Fabio Estevam <fabio.estevam@freescale.com>
Acked-by: Huang Shijie <shijie.huang@intel.com>
Tested-by: Frank Li <Frank.Li@freescale.com>
Acked-by: Allen Xu <han.xu@freescale.com>
Signed-off-by: Brian Norris <computersforpeace@gmail.com>

1 files changed, 13 insertions, 6 deletions

diff --git a/drivers/mtd/spi-nor/fsl-quadspi.c b/drivers/mtd/spi-nor/fsl-quadspi.c
index 9d6080079a45..a46bea33580f 100644
--- a/drivers/mtd/spi-nor/fsl-quadspi.c
+++ b/drivers/mtd/spi-nor/fsl-quadspi.c
@@ -227,6 +227,7 @@ struct fsl_qspi {
         u32 nor_num;
         u32 clk_rate;
         unsigned int chip_base_addr; /* We may support two chips. */
+        bool has_second_chip;
 };
 
 static inline int is_vybrid_qspi(struct fsl_qspi *q)
@@ -783,7 +784,6 @@ static int fsl_qspi_probe(struct platform_device *pdev)
         struct spi_nor *nor;
         struct mtd_info *mtd;
         int ret, i = 0;
-        bool has_second_chip = false;
         const struct of_device_id *of_id =
                         of_match_device(fsl_qspi_dt_ids, &pdev->dev);
 
@@ -860,14 +860,14 @@ static int fsl_qspi_probe(struct platform_device *pdev)
                 goto irq_failed;
 
         if (of_get_property(np, "fsl,qspi-has-second-chip", NULL))
-                has_second_chip = true;
+                q->has_second_chip = true;
 
         /* iterate the subnodes. */
         for_each_available_child_of_node(dev->of_node, np) {
                 char modalias[40];
 
                 /* skip the holes */
-                if (!has_second_chip)
+                if (!q->has_second_chip)
                         i *= 2;
 
                 nor = &q->nor[i];
@@ -943,9 +943,12 @@ static int fsl_qspi_probe(struct platform_device *pdev)
         return 0;
 
 last_init_failed:
-        for (i = 0; i < q->nor_num; i++)
+        for (i = 0; i < q->nor_num; i++) {
+                /* skip the holes */
+                if (!q->has_second_chip)
+                        i *= 2;
                 mtd_device_unregister(&q->mtd[i]);
-
+        }
 irq_failed:
         clk_disable_unprepare(q->clk);
 clk_failed:
@@ -960,8 +963,12 @@ static int fsl_qspi_remove(struct platform_device *pdev)
         struct fsl_qspi *q = platform_get_drvdata(pdev);
         int i;
 
-        for (i = 0; i < q->nor_num; i++)
+        for (i = 0; i < q->nor_num; i++) {
+                /* skip the holes */
+                if (!q->has_second_chip)
+                        i *= 2;
                 mtd_device_unregister(&q->mtd[i]);
+        }
 
         /* disable the hardware */
         writel(QUADSPI_MCR_MDIS_MASK, q->iobase + QUADSPI_MCR);