linux-kernel - [RFC PATCH 2/2] net: stmmac: dwmac-sun8i: Allow runtime AC200/AC300 phy selection

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Message-Id: <20250526002924.2567843-2-james.hilliard1@gmail.com>
Date: Sun, 25 May 2025 18:29:22 -0600
From: James Hilliard <james.hilliard1@...il.com>
To: netdev@...r.kernel.org
Cc: linux-sunxi@...ts.linux.dev,
	James Hilliard <james.hilliard1@...il.com>,
	Andrew Lunn <andrew+netdev@...n.ch>,
	"David S. Miller" <davem@...emloft.net>,
	Eric Dumazet <edumazet@...gle.com>,
	Jakub Kicinski <kuba@...nel.org>,
	Paolo Abeni <pabeni@...hat.com>,
	Chen-Yu Tsai <wens@...e.org>,
	Jernej Skrabec <jernej.skrabec@...il.com>,
	Samuel Holland <samuel@...lland.org>,
	Maxime Coquelin <mcoquelin.stm32@...il.com>,
	Alexandre Torgue <alexandre.torgue@...s.st.com>,
	Yinggang Gu <guyinggang@...ngson.cn>,
	Huacai Chen <chenhuacai@...nel.org>,
	Yanteng Si <si.yanteng@...ux.dev>,
	Feiyang Chen <chenfeiyang@...ngson.cn>,
	Uwe Kleine-König <u.kleine-koenig@...libre.com>,
	"Russell King (Oracle)" <rmk+kernel@...linux.org.uk>,
	Jinjie Ruan <ruanjinjie@...wei.com>,
	Paul Kocialkowski <paulk@...-base.io>,
	linux-arm-kernel@...ts.infradead.org,
	linux-stm32@...md-mailman.stormreply.com,
	linux-kernel@...r.kernel.org
Subject: [RFC PATCH 2/2] net: stmmac: dwmac-sun8i: Allow runtime AC200/AC300 phy selection

The Allwinner H616 ships with two different on-die phy variants, in
order to determine the phy being used we need to read an efuse and
then select the appropriate PHY based on the AC300 bit.

By defining an emac node without a phy-handle we can override the
default PHY selection logic in stmmac by passing a specific phy_node
selected based on the ac200 and ac300 names in a phys list.

This allows us to have a device tree that defines both PHY variants
even though only one will actually end up being used at runtime
based on the ac300 nvmem efuse bit.

Signed-off-by: James Hilliard <james.hilliard1@...il.com>
---
 .../net/ethernet/stmicro/stmmac/dwmac-sun8i.c | 19 +++++++++++++++++++
 1 file changed, 19 insertions(+)

diff --git a/drivers/net/ethernet/stmicro/stmmac/dwmac-sun8i.c b/drivers/net/ethernet/stmicro/stmmac/dwmac-sun8i.c
index 6c7e8655a7eb..e275f4caa684 100644
--- a/drivers/net/ethernet/stmicro/stmmac/dwmac-sun8i.c
+++ b/drivers/net/ethernet/stmicro/stmmac/dwmac-sun8i.c
@@ -11,6 +11,7 @@
 #include <linux/mdio-mux.h>
 #include <linux/mfd/syscon.h>
 #include <linux/module.h>
+#include <linux/nvmem-consumer.h>
 #include <linux/of.h>
 #include <linux/of_mdio.h>
 #include <linux/of_net.h>
@@ -280,6 +281,8 @@ static const struct emac_variant emac_variant_h6 = {
 #define SYSCON_ETCS_EXT_GMII	0x1
 #define SYSCON_ETCS_INT_GMII	0x2
 
+#define AC300_KEY		BIT(8)
+
 /* sun8i_dwmac_dma_reset() - reset the EMAC
  * Called from stmmac via stmmac_dma_ops->reset
  */
@@ -1159,6 +1162,7 @@ static int sun8i_dwmac_probe(struct platform_device *pdev)
 	struct net_device *ndev;
 	struct regmap *regmap;
 	int ret;
+	u16 val;
 
 	ret = stmmac_get_platform_resources(pdev, &stmmac_res);
 	if (ret)
@@ -1222,6 +1226,21 @@ static int sun8i_dwmac_probe(struct platform_device *pdev)
 	if (IS_ERR(plat_dat))
 		return PTR_ERR(plat_dat);
 
+	if (!nvmem_cell_read_u16(dev, "ac300", &val)) {
+		const char *phy_name = (val & AC300_KEY) ? "ac300" : "ac200";
+		int index = of_property_match_string(dev->of_node, "phy-names", phy_name);
+		if (index < 0) {
+			dev_err(dev, "PHY name not found in device tree\n");
+			return -EINVAL;
+		}
+
+		plat_dat->phy_node = of_parse_phandle(dev->of_node, "phys", index);
+		if (!plat_dat->phy_node) {
+			dev_err(dev, "Failed to get PHY node from phys property\n");
+			return -EINVAL;
+		}
+	}
+
 	/* platform data specifying hardware features and callbacks.
 	 * hardware features were copied from Allwinner drivers.
 	 */
-- 
2.34.1