mailbox: mtk-cmdq: add gce ddr enable support flow

add gce ddr enable control flow when gce suspend/resume

when all cmdq instruction task has been processed done,
we need set this gce ddr enable to disable status to tell
cmdq hardware gce there is none task need process, and the hardware
can go into idle mode and no access ddr anymore, then the spm can go
into suspend.

the original issue is gce still access ddr when cmdq suspend function
call, but there is no task run.
so, we need control gce access ddr with this flow.
when cmdq suspend function, there is no task need process, we can
disable gce access ddr, to make sure system go into suspend success.
Signed-off-by: NYongqiang Niu <yongqiang.niu@mediatek.com>
Reviewed-by: NAngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>
Reviewed-by: NCK Hu <ck.hu@mediatek.com>
Signed-off-by: NJassi Brar <jaswinder.singh@linaro.org>

drivers/mailbox/mtk-cmdq-mailbox.c

@@ -94,6 +94,18 @@ struct gce_plat {
 	u32 gce_num;
 };
 
+static void cmdq_sw_ddr_enable(struct cmdq *cmdq, bool enable)
+{
+	WARN_ON(clk_bulk_enable(cmdq->gce_num, cmdq->clocks));
+
+	if (enable)
+		writel(GCE_DDR_EN | GCE_CTRL_BY_SW, cmdq->base + GCE_GCTL_VALUE);
+	else
+		writel(GCE_CTRL_BY_SW, cmdq->base + GCE_GCTL_VALUE);
+
+	clk_bulk_disable(cmdq->gce_num, cmdq->clocks);
+}
+
 u8 cmdq_get_shift_pa(struct mbox_chan *chan)
 {
 	struct cmdq *cmdq = container_of(chan->mbox, struct cmdq, mbox);
@@ -322,6 +334,9 @@ static int cmdq_suspend(struct device *dev)
 	if (task_running)
 		dev_warn(dev, "exist running task(s) in suspend\n");
 
+	if (cmdq->sw_ddr_en)
+		cmdq_sw_ddr_enable(cmdq, false);
+
 	clk_bulk_unprepare(cmdq->gce_num, cmdq->clocks);
 
 	return 0;
@@ -333,6 +348,10 @@ static int cmdq_resume(struct device *dev)
 
 	WARN_ON(clk_bulk_prepare(cmdq->gce_num, cmdq->clocks));
 	cmdq->suspended = false;
+
+	if (cmdq->sw_ddr_en)
+		cmdq_sw_ddr_enable(cmdq, true);
+
 	return 0;
 }
 
@@ -340,6 +359,9 @@ static int cmdq_remove(struct platform_device *pdev)
 {
 	struct cmdq *cmdq = platform_get_drvdata(pdev);
 
+	if (cmdq->sw_ddr_en)
+		cmdq_sw_ddr_enable(cmdq, false);
+
 	clk_bulk_unprepare(cmdq->gce_num, cmdq->clocks);
 	return 0;
 }