soc/mtk_adsp: Remove "msg" API

This is a feature of the 8195 DSP only, which is used only vestigially
by SOF to store data that nothing reads.  The Linux kernel on the
other side uses a shared driver for all 81xx devices, which does not
expose the feature.  It seems to work, but it's not worth maintaining
a driver in tree for legacy hardware that will never use it.

Signed-off-by: Andy Ross <andyross@google.com>

soc/mediatek/mtk_adsp/mbox.c

@@ -65,25 +65,6 @@ void mtk_adsp_mbox_set_handler(const struct device *mbox, uint32_t chan,
 	}
 }
 
-void mtk_adsp_mbox_set_msg(const struct device *mbox, uint32_t idx, uint32_t val)
-{
-	const struct mbox_cfg *cfg = ((struct device *)mbox)->config;
-
-	if (idx < MTK_ADSP_MBOX_MSG_WORDS) {
-		cfg->mbox->out_msg[idx] = val;
-	}
-}
-
-uint32_t mtk_adsp_mbox_get_msg(const struct device *mbox, uint32_t idx)
-{
-	const struct mbox_cfg *cfg = ((struct device *)mbox)->config;
-
-	if (idx < MTK_ADSP_MBOX_MSG_WORDS) {
-		return cfg->mbox->in_msg[idx];
-	}
-	return 0;
-}
-
 void mtk_adsp_mbox_signal(const struct device *mbox, uint32_t chan)
 {
 	const struct mbox_cfg *cfg = ((struct device *)mbox)->config;

soc/mediatek/mtk_adsp/soc.h

@@ -23,13 +23,6 @@ typedef void (*mtk_adsp_mbox_handler_t)(const struct device *mbox, void *arg);
 void mtk_adsp_mbox_set_handler(const struct device *mbox, uint32_t chan,
 			       mtk_adsp_mbox_handler_t handler, void *arg);
 
-/* Mailbox hardware has an array of unstructured "message" data in
- * each direction.  Any value can be placed in the registers.
- */
-#define MTK_ADSP_MBOX_MSG_WORDS 5
-void mtk_adsp_mbox_set_msg(const struct device *mbox, uint32_t idx, uint32_t val);
-uint32_t mtk_adsp_mbox_get_msg(const struct device *mbox, uint32_t idx);
-
 /* Signal an interrupt on the specified channel for the other side */
 void mtk_adsp_mbox_signal(const struct device *mbox, uint32_t chan);
 

tests/boards/mtk_adsp/src/main.c

@@ -69,10 +69,7 @@ static void mbox_fn(const struct device *mbox, void *arg)
 /* Test in/out interrupts from the host.  This relies on a SOF driver
  * on the host, which has the behavior of "replying" with an interrupt
  * on mbox1 after receiving a "command" on mbox0 (you can also see it
- * whine about the invalid IPC message in the kernel logs).  SOF
+ * whine about the invalid IPC message in the kernel logs).
- * ignores the message bytes (it uses a DRAM area instead), so we just
- * write them blindly.  It's only a partial test of the hardware, but
- * easy to run and exercises the core functionality.
  *
  * Note that there's a catch: SOF's "reply" comes after a timeout
  * (it's an invalid command, afterall) which is 165 seconds!  But the
@@ -82,10 +79,6 @@ ZTEST(mtk_adsp, mbox)
 {
 	mtk_adsp_mbox_set_handler(MBOX1, 1, mbox_fn, NULL);
 
-	for (int i = 0; i < MTK_ADSP_MBOX_MSG_WORDS; i++) {
-		mtk_adsp_mbox_set_msg(MBOX0, i, 0x01010100 | i);
-	}
-
 	/* First signal the host with a reply on the second channel,
 	 * that effects a reply to anything it thinks it might have
 	 * sent us