[PATCH resend] regmap: mmio: Fix the bug of 'offset' value parsing.

[Xiubo Li]

'offset = *(u32 *)reg;'
This will be okey for 32/64-bits register device, but for 8/16-bits
register ones, the 'offset' value will overflow, for example:

The IMX2 Watchdog, whose registers and values are all 16-bits:

If the IO base virtual address is ctx->regs = 0x888c0000, and the now
doing the 0x00 register accessing:
Using 'offset = *(u32 *)reg' the offset value will possiblly be 0x77310000,
Using 'offset = *(u16 *)reg' the offset value will be 0x0000.

In the regmap_mmio_gather_write(), ctx->regs + 0x7731000 will be 0xffbd0000,
but actually it should be ctx->regs + 0x0000 = 0x888c0000.

Signed-off-by: Xiubo Li <li.xi...@freescale.com>
---
 drivers/base/regmap/regmap-mmio.c | 29 ++++++++++++++++++++++++-----
 1 file changed, 24 insertions(+), 5 deletions(-)

diff --git a/drivers/base/regmap/regmap-mmio.c 
b/drivers/base/regmap/regmap-mmio.c
index de45a1e..e1b42c5 100644
--- a/drivers/base/regmap/regmap-mmio.c
+++ b/drivers/base/regmap/regmap-mmio.c
@@ -67,12 +67,31 @@ static inline void regmap_mmio_count_check(size_t count)
        BUG_ON(count % 2 != 0);
 }
 
+static inline unsigned int
+regmap_mmio_get_offset(const void *reg, size_t reg_size)
+{
+       switch (reg_size) {
+       case 1:
+               return *(u8 *)reg;
+       case 2:
+               return *(u16 *)reg;
+       case 4:
+               return *(u32 *)reg;
+#ifdef CONFIG_64BIT
+       case 8:
+               return *(u64 *)reg;
+#endif
+       default:
+               BUG();
+       }
+}
+
 static int regmap_mmio_gather_write(void *context,
                                    const void *reg, size_t reg_size,
                                    const void *val, size_t val_size)
 {
        struct regmap_mmio_context *ctx = context;
-       u32 offset;
+       unsigned int offset;
        int ret;
 
        regmap_mmio_regsize_check(reg_size);
@@ -83,7 +102,7 @@ static int regmap_mmio_gather_write(void *context,
                        return ret;
        }
 
-       offset = *(u32 *)reg;
+       offset = regmap_mmio_get_offset(reg, reg_size);
 
        while (val_size) {
                switch (ctx->val_bytes) {
@@ -119,7 +138,7 @@ static int regmap_mmio_gather_write(void *context,
 static int regmap_mmio_write(void *context, const void *data, size_t count)
 {
        struct regmap_mmio_context *ctx = context;
-       u32 offset = ctx->reg_bytes + ctx->pad_bytes;
+       unsigned int offset = ctx->reg_bytes + ctx->pad_bytes;
 
        regmap_mmio_count_check(count);
 
@@ -132,7 +151,7 @@ static int regmap_mmio_read(void *context,
                            void *val, size_t val_size)
 {
        struct regmap_mmio_context *ctx = context;
-       u32 offset;
+       unsigned int offset;
        int ret;
 
        regmap_mmio_regsize_check(reg_size);
@@ -143,7 +162,7 @@ static int regmap_mmio_read(void *context,
                        return ret;
        }
 
-       offset = *(u32 *)reg;
+       offset = regmap_mmio_get_offset(reg, reg_size);
 
        while (val_size) {
                switch (ctx->val_bytes) {
-- 
1.8.4


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