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path: root/drivers/firmware/meson/meson_sm.c
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Diffstat (limited to 'drivers/firmware/meson/meson_sm.c')
-rw-r--r--drivers/firmware/meson/meson_sm.c20
1 files changed, 16 insertions, 4 deletions
diff --git a/drivers/firmware/meson/meson_sm.c b/drivers/firmware/meson/meson_sm.c
index b0d254930ed3..ff204421117b 100644
--- a/drivers/firmware/meson/meson_sm.c
+++ b/drivers/firmware/meson/meson_sm.c
@@ -127,6 +127,7 @@ EXPORT_SYMBOL(meson_sm_call);
* meson_sm_call_read - retrieve data from secure-monitor
*
* @buffer: Buffer to store the retrieved data
+ * @bsize: Size of the buffer
* @cmd_index: Index of the SMC32 function ID
* @arg0: SMC32 Argument 0
* @arg1: SMC32 Argument 1
@@ -135,11 +136,14 @@ EXPORT_SYMBOL(meson_sm_call);
* @arg4: SMC32 Argument 4
*
* Return: size of read data on success, a negative value on error
+ * When 0 is returned there is no guarantee about the amount of
+ * data read and bsize bytes are copied in buffer.
*/
-int meson_sm_call_read(void *buffer, unsigned int cmd_index, u32 arg0,
- u32 arg1, u32 arg2, u32 arg3, u32 arg4)
+int meson_sm_call_read(void *buffer, unsigned int bsize, unsigned int cmd_index,
+ u32 arg0, u32 arg1, u32 arg2, u32 arg3, u32 arg4)
{
u32 size;
+ int ret;
if (!fw.chip)
return -ENOENT;
@@ -147,16 +151,24 @@ int meson_sm_call_read(void *buffer, unsigned int cmd_index, u32 arg0,
if (!fw.chip->cmd_shmem_out_base)
return -EINVAL;
+ if (bsize > fw.chip->shmem_size)
+ return -EINVAL;
+
if (meson_sm_call(cmd_index, &size, arg0, arg1, arg2, arg3, arg4) < 0)
return -EINVAL;
- if (!size || size > fw.chip->shmem_size)
+ if (size > bsize)
return -EINVAL;
+ ret = size;
+
+ if (!size)
+ size = bsize;
+
if (buffer)
memcpy(buffer, fw.sm_shmem_out_base, size);
- return size;
+ return ret;
}
EXPORT_SYMBOL(meson_sm_call_read);