mailbox: mpfs: account for mbox offsets while sending

The mailbox offset is not only used for receiving messages, but it is
also used by messages sent to the system controller by Linux that have a
payload, such as the "digital signature service". It is also overloaded
by certain other services (reprogramming of the FPGA fabric, see Link:)
to have a meaning other than the offset the system controller should
read from.
When the driver was written, no such services of the latter type were
in use & those of the former used an offset of zero so this has gone
un-noticed.

Link: https://www.microsemi.com/document-portal/doc_download/1245815-polarfire-fpga-and-polarfire-soc-fpga-system-services-user-guide
Fixes: 83d7b1560810 ("mbox: add polarfire soc system controller mailbox")
Signed-off-by: Conor Dooley <conor.dooley@microchip.com>
Signed-off-by: Jassi Brar <jaswinder.singh@linaro.org>

diff --git a/drivers/mailbox/mailbox-mpfs.c b/drivers/mailbox/mailbox-mpfs.c
index e432a8f0d14851d2b3b42c12da15628475a3726c..cfacb3f320a6438cba4717c135317f492cc455a8 100644 (file)
--- a/drivers/mailbox/mailbox-mpfs.c
+++ b/drivers/mailbox/mailbox-mpfs.c
@@ -100,21 +100,20 @@ static int mpfs_mbox_send_data(struct mbox_chan *chan, void *data)
 
                for (index = 0; index < (msg->cmd_data_size / 4); index++)
                        writel_relaxed(word_buf[index],
-                                      mbox->mbox_base + index * 0x4);
+                                      mbox->mbox_base + msg->mbox_offset + index * 0x4);
                if (extra_bits) {
                        u8 i;
                        u8 byte_off = ALIGN_DOWN(msg->cmd_data_size, 4);
                        u8 *byte_buf = msg->cmd_data + byte_off;
 
-                       val = readl_relaxed(mbox->mbox_base + index * 0x4);
+                       val = readl_relaxed(mbox->mbox_base + msg->mbox_offset + index * 0x4);
 
                        for (i = 0u; i < extra_bits; i++) {
                                val &= ~(0xffu << (i * 8u));
                                val |= (byte_buf[i] << (i * 8u));
                        }
 
-                       writel_relaxed(val,
-                                      mbox->mbox_base + index * 0x4);
+                       writel_relaxed(val, mbox->mbox_base + msg->mbox_offset + index * 0x4);
                }
        }