Subject: Re: Re: Re: [PATCH v2] net: mtk_sgmii: implement mtk_pcs_ops

From: "Russell King (Oracle)" <[email-masked]>
Date: Mon, 24 Oct 2022 10:27:35 +0100

On Sun, Oct 23, 2022 at 09:09:23PM +0100, Russell King (Oracle) wrote:
> This is amazingly great news - we now know how to configure this
> hardware! Let me cook up a proper set of patches for tomorrow - if
> that's okay.

Here's the combined patch for where I would like mtk_sgmii to get to.

It looks like this PCS is similar to what we know as pcs-lynx.c, but
there do seem to be differences - the duplex bit for example appears
to be inverted.

Please confirm whether this still works for you, thanks.

diff --git a/drivers/net/ethernet/mediatek/mtk_eth_soc.h b/drivers/net/ethernet/mediatek/mtk_eth_soc.h
index b52f3b0177ef..8ecf97bcfec6 100644
--- a/drivers/net/ethernet/mediatek/mtk_eth_soc.h
+++ b/drivers/net/ethernet/mediatek/mtk_eth_soc.h
@@ -466,8 +466,10 @@
 #define ETHSYS_DMA_AG_MAP_PPE	BIT(2)
 
 /* SGMII subsystem config registers */
-/* Register to auto-negotiation restart */
+/* BMCR (low 16) BMSR (high 16) */
 #define SGMSYS_PCS_CONTROL_1	0x0
+#define SGMII_BMCR		GENMASK(15, 0)
+#define SGMII_BMSR		GENMASK(31, 16)
 #define SGMII_AN_RESTART	BIT(9)
 #define SGMII_ISOLATE		BIT(10)
 #define SGMII_AN_ENABLE		BIT(12)
@@ -477,9 +479,13 @@
 #define SGMII_PCS_FAULT		BIT(23)
 #define SGMII_AN_EXPANSION_CLR	BIT(30)
 
+#define SGMSYS_PCS_ADVERTISE	0x8
+#define SGMII_ADVERTISE		GENMASK(15, 0)
+#define SGMII_LPA		GENMASK(31, 16)
+
 /* Register to programmable link timer, the unit in 2 * 8ns */
 #define SGMSYS_PCS_LINK_TIMER	0x18
-#define SGMII_LINK_TIMER_DEFAULT	(0x186a0 & GENMASK(19, 0))
+#define SGMII_LINK_TIMER_MASK	GENMASK(19, 0)
 
 /* Register to control remote fault */
 #define SGMSYS_SGMII_MODE		0x20
diff --git a/drivers/net/ethernet/mediatek/mtk_sgmii.c b/drivers/net/ethernet/mediatek/mtk_sgmii.c
index 736839c84130..e64c02a48449 100644
--- a/drivers/net/ethernet/mediatek/mtk_sgmii.c
+++ b/drivers/net/ethernet/mediatek/mtk_sgmii.c
@@ -19,110 +19,136 @@ static struct mtk_pcs *pcs_to_mtk_pcs(struct phylink_pcs *pcs)
 	return container_of(pcs, struct mtk_pcs, pcs);
 }
 
-/* For SGMII interface mode */
-static int mtk_pcs_setup_mode_an(struct mtk_pcs *mpcs)
+static void mtk_pcs_get_state(struct phylink_pcs *pcs,
+			      struct phylink_link_state *state)
 {
-	unsigned int val;
-
-	/* Setup the link timer and QPHY power up inside SGMIISYS */
-	regmap_write(mpcs->regmap, SGMSYS_PCS_LINK_TIMER,
-		     SGMII_LINK_TIMER_DEFAULT);
-
-	regmap_read(mpcs->regmap, SGMSYS_SGMII_MODE, &val);
-	val |= SGMII_REMOTE_FAULT_DIS;
-	regmap_write(mpcs->regmap, SGMSYS_SGMII_MODE, val);
-
-	regmap_read(mpcs->regmap, SGMSYS_PCS_CONTROL_1, &val);
-	val |= SGMII_AN_RESTART;
-	regmap_write(mpcs->regmap, SGMSYS_PCS_CONTROL_1, val);
-
-	regmap_read(mpcs->regmap, SGMSYS_QPHY_PWR_STATE_CTRL, &val);
-	val &= ~SGMII_PHYA_PWD;
-	regmap_write(mpcs->regmap, SGMSYS_QPHY_PWR_STATE_CTRL, val);
+	struct mtk_pcs *mpcs = pcs_to_mtk_pcs(pcs);
+	unsigned int bm, adv;
 
-	return 0;
+	/* Read the BMSR and LPA */
+	regmap_read(mpcs->regmap, SGMSYS_PCS_CONTROL_1, &bm);
+	regmap_read(mpcs->regmap, SGMSYS_PCS_ADVERTISE, &adv);
 
+	phylink_mii_c22_pcs_decode_state(state, FIELD_GET(SGMII_BMSR, bm),
+					 FIELD_GET(SGMII_LPA, adv));
 }
 
-/* For 1000BASE-X and 2500BASE-X interface modes, which operate at a
- * fixed speed.
- */
-static int mtk_pcs_setup_mode_force(struct mtk_pcs *mpcs,
-				    phy_interface_t interface)
+static int mtk_pcs_config(struct phylink_pcs *pcs, unsigned int mode,
+			  phy_interface_t interface,
+			  const unsigned long *advertising,
+			  bool permit_pause_to_mac)
 {
-	unsigned int val;
+	struct mtk_pcs *mpcs = pcs_to_mtk_pcs(pcs);
+	unsigned int rgc3, sgm_mode, bmcr;
+	int advertise, link_timer;
+	bool changed, use_an;
 
-	regmap_read(mpcs->regmap, mpcs->ana_rgc3, &val);
-	val &= ~RG_PHY_SPEED_MASK;
 	if (interface == PHY_INTERFACE_MODE_2500BASEX)
-		val |= RG_PHY_SPEED_3_125G;
-	regmap_write(mpcs->regmap, mpcs->ana_rgc3, val);
+		rgc3 = RG_PHY_SPEED_3_125G;
+	else
+		rgc3 = 0;
+
+	advertise = phylink_mii_c22_pcs_encode_advertisement(interface,
+							     advertising);
+	if (advertise < 0)
+		return advertise;
+
+	link_timer = phylink_get_link_timer_ns(interface);
+	if (link_timer < 0)
+		return link_timer;
+
+	/* Clearing IF_MODE_BIT0 switches the PCS to BASE-X mode, and
+	 * we assume that fixes it's speed at bitrate = line rate (in
+	 * other words, 1000Mbps or 2500Mbps).
+	 */
+	if (interface == PHY_INTERFACE_MODE_SGMII) {
+		sgm_mode = SGMII_IF_MODE_BIT0;
+		if (phylink_autoneg_inband(mode)) {
+			sgm_mode |= SGMII_REMOTE_FAULT_DIS |
+				    SGMII_SPEED_DUPLEX_AN;
+			use_an = true;
+		} else {
+			use_an = false;
+		}
+	} else if (phylink_autoneg_inband(mode)) {
+		/* 1000base-X or 2500base-X autoneg */
+		sgm_mode = SGMII_REMOTE_FAULT_DIS;
+		use_an = linkmode_test_bit(ETHTOOL_LINK_MODE_Autoneg_BIT,
+					   advertising);
+	} else {
+		/* 1000base-X or 2500base-X without autoneg */
+		sgm_mode = 0;
+		use_an = false;
+	}
 
-	/* Disable SGMII AN */
-	regmap_read(mpcs->regmap, SGMSYS_PCS_CONTROL_1, &val);
-	val &= ~SGMII_AN_ENABLE;
-	regmap_write(mpcs->regmap, SGMSYS_PCS_CONTROL_1, val);
+	if (use_an) {
+		/* FIXME: Do we need to set AN_RESTART here? */
+		bmcr = SGMII_AN_RESTART | SGMII_AN_ENABLE;
+	} else {
+		bmcr = 0;
+	}
 
-	/* Set the speed etc but leave the duplex unchanged */
-	regmap_read(mpcs->regmap, SGMSYS_SGMII_MODE, &val);
-	val &= SGMII_DUPLEX_FULL | ~SGMII_IF_MODE_MASK;
-	val |= SGMII_SPEED_1000;
-	regmap_write(mpcs->regmap, SGMSYS_SGMII_MODE, val);
+	/* Configure the underlying interface speed */
+	regmap_update_bits(mpcs->regmap, mpcs->ana_rgc3,
+			   RG_PHY_SPEED_3_125G, rgc3);
 
-	/* Release PHYA power down state */
-	regmap_read(mpcs->regmap, SGMSYS_QPHY_PWR_STATE_CTRL, &val);
-	val &= ~SGMII_PHYA_PWD;
-	regmap_write(mpcs->regmap, SGMSYS_QPHY_PWR_STATE_CTRL, val);
+	/* Update the advertisement, noting whether it has changed */
+	regmap_update_bits_check(mpcs->regmap, SGMSYS_PCS_ADVERTISE,
+				 SGMII_ADVERTISE, advertise, &changed);
 
-	return 0;
-}
+	/* Setup the link timer and QPHY power up inside SGMIISYS */
+	regmap_write(mpcs->regmap, SGMSYS_PCS_LINK_TIMER, link_timer / 2 / 8);
 
-static int mtk_pcs_config(struct phylink_pcs *pcs, unsigned int mode,
-			  phy_interface_t interface,
-			  const unsigned long *advertising,
-			  bool permit_pause_to_mac)
-{
-	struct mtk_pcs *mpcs = pcs_to_mtk_pcs(pcs);
-	int err = 0;
+	/* Update the sgmsys mode register */
+	regmap_update_bits(mpcs->regmap, SGMSYS_SGMII_MODE,
+			   SGMII_REMOTE_FAULT_DIS | SGMII_SPEED_DUPLEX_AN |
+			   SGMII_IF_MODE_BIT0, sgm_mode);
+
+	/* Update the BMCR */
+	regmap_update_bits(mpcs->regmap, SGMSYS_PCS_CONTROL_1,
+			   SGMII_AN_RESTART | SGMII_AN_ENABLE, bmcr);
 
-	/* Setup SGMIISYS with the determined property */
-	if (interface != PHY_INTERFACE_MODE_SGMII)
-		err = mtk_pcs_setup_mode_force(mpcs, interface);
-	else if (phylink_autoneg_inband(mode))
-		err = mtk_pcs_setup_mode_an(mpcs);
+	/* Release PHYA power down state */
+	regmap_update_bits(mpcs->regmap, SGMSYS_QPHY_PWR_STATE_CTRL,
+			   SGMII_PHYA_PWD, 0);
 
-	return err;
+	return changed ? 1 : 0;
 }
 
 static void mtk_pcs_restart_an(struct phylink_pcs *pcs)
 {
 	struct mtk_pcs *mpcs = pcs_to_mtk_pcs(pcs);
-	unsigned int val;
 
-	regmap_read(mpcs->regmap, SGMSYS_PCS_CONTROL_1, &val);
-	val |= SGMII_AN_RESTART;
-	regmap_write(mpcs->regmap, SGMSYS_PCS_CONTROL_1, val);
+	regmap_update_bits(mpcs->regmap, SGMSYS_PCS_CONTROL_1,
+			   SGMII_AN_RESTART, SGMII_AN_RESTART);
 }
 
 static void mtk_pcs_link_up(struct phylink_pcs *pcs, unsigned int mode,
 			    phy_interface_t interface, int speed, int duplex)
 {
 	struct mtk_pcs *mpcs = pcs_to_mtk_pcs(pcs);
-	unsigned int val;
-
-	if (!phy_interface_mode_is_8023z(interface))
-		return;
-
-	/* SGMII force duplex setting */
-	regmap_read(mpcs->regmap, SGMSYS_SGMII_MODE, &val);
-	val &= ~SGMII_DUPLEX_FULL;
-	if (duplex == DUPLEX_FULL)
-		val |= SGMII_DUPLEX_FULL;
-
-	regmap_write(mpcs->regmap, SGMSYS_SGMII_MODE, val);
+	unsigned int sgm_mode;
+
+	if (!phylink_autoneg_inband(mode)) {
+		/* Force the speed and duplex setting */
+		if (speed == SPEED_10)
+			sgm_mode = SGMII_SPEED_10;
+		else if (speed == SPEED_100)
+			sgm_mode = SGMII_SPEED_100;
+		else
+			sgm_mode = SGMII_SPEED_1000;
+
+		if (duplex == DUPLEX_FULL)
+			sgm_mode |= SGMII_DUPLEX_FULL;
+
+		regmap_update_bits(mpcs->regmap, SGMSYS_SGMII_MODE,
+				   SGMII_DUPLEX_FULL | SGMII_SPEED_MASK,
+				   sgm_mode);
+	}
 }
 
 static const struct phylink_pcs_ops mtk_pcs_ops = {
+	.pcs_get_state = mtk_pcs_get_state,
 	.pcs_config = mtk_pcs_config,
 	.pcs_an_restart = mtk_pcs_restart_an,
 	.pcs_link_up = mtk_pcs_link_up,
diff --git a/include/linux/phylink.h b/include/linux/phylink.h
index 63800bf4a7ac..7a3eb46b38c1 100644
--- a/include/linux/phylink.h
+++ b/include/linux/phylink.h
@@ -616,6 +616,22 @@ int phylink_speed_up(struct phylink *pl);
 
 void phylink_set_port_modes(unsigned long *bits);
 
+static inline int phylink_get_link_timer_ns(phy_interface_t interface)
+{
+	switch (interface) {
+	case PHY_INTERFACE_MODE_SGMII:
+	case PHY_INTERFACE_MODE_QSGMII:
+		return 1600000;
+
+	case PHY_INTERFACE_MODE_1000BASEX:
+	case PHY_INTERFACE_MODE_2500BASEX:
+		return 10000000;
+
+	default:
+		return -EINVAL;
+	}
+}
+
 void phylink_mii_c22_pcs_decode_state(struct phylink_link_state *state,
 				      u16 bmsr, u16 lpa);
 void phylink_mii_c22_pcs_get_state(struct mdio_device *pcs,

-- 
RMK's Patch system: https://www.armlinux.org.uk/developer/patches/
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