[PATCH 2/2] mailbox: imx: support RST channel

[Peng Fan (OSS)]

From: Peng Fan <peng.fan at nxp.com>

i.MX generic MU supports MU-A/B reset feature.

When stop/start remotecore, MU is not reset. So when Linux stop
remotecore, the MU-B side BCR may contain valid configuration,
because MU-B is not reset. So when linux start Mcore
again and notify Mcore, Mcore is not ready to handle MU interrupt
and cause issues. So need reset MU when stop Mcore.

Signed-off-by: Peng Fan <peng.fan at nxp.com>
---
 drivers/mailbox/imx-mailbox.c | 29 +++++++++++++++++++++++------
 1 file changed, 23 insertions(+), 6 deletions(-)

diff --git a/drivers/mailbox/imx-mailbox.c b/drivers/mailbox/imx-mailbox.c
index e88f544a1548..ce05ddc8402c 100644
--- a/drivers/mailbox/imx-mailbox.c
+++ b/drivers/mailbox/imx-mailbox.c
@@ -19,7 +19,7 @@
 #include <linux/suspend.h>
 #include <linux/slab.h>
 
-#define IMX_MU_CHANS		16
+#define IMX_MU_CHANS		17
 /* TX0/RX0/RXDB[0-3] */
 #define IMX_MU_SCU_CHANS	6
 /* TX0/RX0 */
@@ -35,9 +35,11 @@ enum imx_mu_chan_type {
 	IMX_MU_TYPE_RX		= 1, /* Rx */
 	IMX_MU_TYPE_TXDB	= 2, /* Tx doorbell */
 	IMX_MU_TYPE_RXDB	= 3, /* Rx doorbell */
+	IMX_MU_TYPE_RST		= 4, /* Reset */
 };
 
 enum imx_mu_xcr {
+	IMX_MU_CR,
 	IMX_MU_GIER,
 	IMX_MU_GCR,
 	IMX_MU_TCR,
@@ -50,6 +52,7 @@ enum imx_mu_xsr {
 	IMX_MU_GSR,
 	IMX_MU_TSR,
 	IMX_MU_RSR,
+	IMX_MU_xSR_MAX,
 };
 
 struct imx_sc_rpc_msg_max {
@@ -85,7 +88,7 @@ struct imx_mu_priv {
 	int			irq[IMX_MU_CHANS];
 	bool			suspend;
 
-	u32 xcr[4];
+	u32 xcr[IMX_MU_xCR_MAX];
 
 	bool			side_b;
 };
@@ -105,8 +108,8 @@ struct imx_mu_dcfg {
 	enum imx_mu_type type;
 	u32	xTR;		/* Transmit Register0 */
 	u32	xRR;		/* Receive Register0 */
-	u32	xSR[4];		/* Status Registers */
-	u32	xCR[4];		/* Control Registers */
+	u32	xSR[IMX_MU_xSR_MAX];	/* Status Registers */
+	u32	xCR[IMX_MU_xCR_MAX];	/* Control Registers */
 };
 
 #define IMX_MU_xSR_GIPn(type, x) (type & IMX_MU_V2 ? BIT(x) : BIT(28 + (3 - (x))))
@@ -121,6 +124,9 @@ struct imx_mu_dcfg {
 #define IMX_MU_xCR_TIEn(type, x) (type & IMX_MU_V2 ? BIT(x) : BIT(20 + (3 - (x))))
 /* General Purpose Interrupt Request */
 #define IMX_MU_xCR_GIRn(type, x) (type & IMX_MU_V2 ? BIT(x) : BIT(16 + (3 - (x))))
+/* MU reset */
+#define IMX_MU_xCR_RST(type)	(type & IMX_MU_V2 ? BIT(0) : BIT(5))
+#define IMX_MU_xSR_RST(type)	(type & IMX_MU_V2 ? BIT(0) : BIT(7))
 
 
 static struct imx_mu_priv *to_imx_mu_priv(struct mbox_controller *mbox)
@@ -497,6 +503,8 @@ static irqreturn_t imx_mu_isr(int irq, void *p)
 		val &= IMX_MU_xSR_GIPn(priv->dcfg->type, cp->idx) &
 			(ctrl & IMX_MU_xCR_GIEn(priv->dcfg->type, cp->idx));
 		break;
+	case IMX_MU_TYPE_RST:
+		return IRQ_NONE;
 	default:
 		dev_warn_ratelimited(priv->dev, "Unhandled channel type %d\n",
 				     cp->type);
@@ -581,6 +589,8 @@ static void imx_mu_shutdown(struct mbox_chan *chan)
 {
 	struct imx_mu_priv *priv = to_imx_mu_priv(chan->mbox);
 	struct imx_mu_con_priv *cp = chan->con_priv;
+	int ret;
+	u32 sr;
 
 	if (cp->type == IMX_MU_TYPE_TXDB) {
 		tasklet_kill(&cp->txdb_tasklet);
@@ -598,6 +608,13 @@ static void imx_mu_shutdown(struct mbox_chan *chan)
 	case IMX_MU_TYPE_RXDB:
 		imx_mu_xcr_rmw(priv, IMX_MU_GIER, 0, IMX_MU_xCR_GIEn(priv->dcfg->type, cp->idx));
 		break;
+	case IMX_MU_TYPE_RST:
+		imx_mu_xcr_rmw(priv, IMX_MU_CR, IMX_MU_xCR_RST(priv->dcfg->type), 0);
+		ret = readl_poll_timeout(priv->base + priv->dcfg->xSR[IMX_MU_SR], sr,
+					 !(sr & IMX_MU_xSR_RST(priv->dcfg->type)), 1, 5);
+		if (ret)
+			dev_warn(priv->dev, "RST channel timeout\n");
+		break;
 	default:
 		break;
 	}
@@ -867,7 +884,7 @@ static const struct imx_mu_dcfg imx_mu_cfg_imx6sx = {
 	.xTR	= 0x0,
 	.xRR	= 0x10,
 	.xSR	= {0x20, 0x20, 0x20, 0x20},
-	.xCR	= {0x24, 0x24, 0x24, 0x24},
+	.xCR	= {0x24, 0x24, 0x24, 0x24, 0x24},
 };
 
 static const struct imx_mu_dcfg imx_mu_cfg_imx7ulp = {
@@ -891,7 +908,7 @@ static const struct imx_mu_dcfg imx_mu_cfg_imx8ulp = {
 	.xTR	= 0x200,
 	.xRR	= 0x280,
 	.xSR	= {0xC, 0x118, 0x124, 0x12C},
-	.xCR	= {0x110, 0x114, 0x120, 0x128},
+	.xCR	= {0x8, 0x110, 0x114, 0x120, 0x128},
 };
 
 static const struct imx_mu_dcfg imx_mu_cfg_imx8ulp_s4 = {
-- 
2.25.1