net: ethernet: mtk_eth_soc: introduce mtk_hw_warm_reset support

Introduce mtk_hw_warm_reset utility routine. This is a preliminary patch
to align reset procedure to vendor sdk and avoid to power down the chip
during hw reset.

Reviewed-by: Leon Romanovsky <leonro@nvidia.com>
Tested-by: Daniel Golle <daniel@makrotopia.org>
Co-developed-by: Sujuan Chen <sujuan.chen@mediatek.com>
Signed-off-by: Sujuan Chen <sujuan.chen@mediatek.com>
Signed-off-by: Lorenzo Bianconi <lorenzo@kernel.org>
Signed-off-by: Paolo Abeni <pabeni@redhat.com>

drivers/net/ethernet/mediatek/mtk_eth_soc.c

@@ -3538,7 +3538,54 @@ static void mtk_hw_reset(struct mtk_eth *eth)
 			     0x3ffffff);
 }
 
-static int mtk_hw_init(struct mtk_eth *eth)
+static u32 mtk_hw_reset_read(struct mtk_eth *eth)
+{
+	u32 val;
+
+	regmap_read(eth->ethsys, ETHSYS_RSTCTRL, &val);
+	return val;
+}
+
+static void mtk_hw_warm_reset(struct mtk_eth *eth)
+{
+	u32 rst_mask, val;
+
+	regmap_update_bits(eth->ethsys, ETHSYS_RSTCTRL, RSTCTRL_FE,
+			   RSTCTRL_FE);
+	if (readx_poll_timeout_atomic(mtk_hw_reset_read, eth, val,
+				      val & RSTCTRL_FE, 1, 1000)) {
+		dev_err(eth->dev, "warm reset failed\n");
+		mtk_hw_reset(eth);
+		return;
+	}
+
+	if (MTK_HAS_CAPS(eth->soc->caps, MTK_NETSYS_V2))
+		rst_mask = RSTCTRL_ETH | RSTCTRL_PPE0_V2;
+	else
+		rst_mask = RSTCTRL_ETH | RSTCTRL_PPE0;
+
+	if (MTK_HAS_CAPS(eth->soc->caps, MTK_RSTCTRL_PPE1))
+		rst_mask |= RSTCTRL_PPE1;
+
+	regmap_update_bits(eth->ethsys, ETHSYS_RSTCTRL, rst_mask, rst_mask);
+
+	udelay(1);
+	val = mtk_hw_reset_read(eth);
+	if (!(val & rst_mask))
+		dev_err(eth->dev, "warm reset stage0 failed %08x (%08x)\n",
+			val, rst_mask);
+
+	rst_mask |= RSTCTRL_FE;
+	regmap_update_bits(eth->ethsys, ETHSYS_RSTCTRL, rst_mask, ~rst_mask);
+
+	udelay(1);
+	val = mtk_hw_reset_read(eth);
+	if (val & rst_mask)
+		dev_err(eth->dev, "warm reset stage1 failed %08x (%08x)\n",
+			val, rst_mask);
+}
+
+static int mtk_hw_init(struct mtk_eth *eth, bool reset)
 {
 	u32 dma_mask = ETHSYS_DMA_AG_MAP_PDMA | ETHSYS_DMA_AG_MAP_QDMA |
 		       ETHSYS_DMA_AG_MAP_PPE;
@@ -3577,7 +3624,12 @@ static int mtk_hw_init(struct mtk_eth *eth)
 		return 0;
 	}
 
-	mtk_hw_reset(eth);
+	msleep(100);
+
+	if (reset)
+		mtk_hw_warm_reset(eth);
+	else
+		mtk_hw_reset(eth);
 
 	if (MTK_HAS_CAPS(eth->soc->caps, MTK_NETSYS_V2)) {
 		/* Set FE to PDMAv2 if necessary */
@@ -3789,7 +3841,7 @@ static void mtk_pending_work(struct work_struct *work)
 	if (eth->dev->pins)
 		pinctrl_select_state(eth->dev->pins->p,
 				     eth->dev->pins->default_state);
-	mtk_hw_init(eth);
+	mtk_hw_init(eth, true);
 
 	/* restart DMA and enable IRQs */
 	for (i = 0; i < MTK_MAC_COUNT; i++) {
@@ -4418,7 +4470,7 @@ static int mtk_probe(struct platform_device *pdev)
 	eth->msg_enable = netif_msg_init(mtk_msg_level, MTK_DEFAULT_MSG_ENABLE);
 	INIT_WORK(&eth->pending_work, mtk_pending_work);
 
-	err = mtk_hw_init(eth);
+	err = mtk_hw_init(eth, false);
 	if (err)
 		goto err_wed_exit;