phy: cadence-torrent: add support for three or more links using 2 protocols

The Torrent SERDES can support at most two different protocols (PHY types).
This only mandates that the device-tree sub-nodes used to represent the
configuration should describe links with at-most two different protocols.

The existing implementation however imposes an artificial constraint that
allows only two links (device-tree sub-nodes). As long as at-most two
protocols are chosen, using more than two links to describe them in an
alternating configuration is still a valid configuration of the Torrent
SERDES.

A 3-Link 2-Protocol configuration of the 4-Lane SERDES can be:
Lane 0 => Protocol 1 => Link 1
Lane 1 => Protocol 1 => Link 1
Lane 2 => Protocol 2 => Link 2
Lane 3 => Protocol 1 => Link 3

A 4-Link 2-Protocol configuration of the 4-Lane SERDES can be:
Lane 0 => Protocol 1 => Link 1
Lane 1 => Protocol 2 => Link 2
Lane 2 => Protocol 1 => Link 3
Lane 3 => Protocol 2 => Link 4

Signed-off-by: Siddharth Vadapalli <[email protected]>
Reviewed-by: Roger Quadros <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Vinod Koul <[email protected]>

Author: Siddharth-Vadapalli-at-TI

drivers/phy/cadence/phy-cadence-torrent.c

@@ -351,6 +351,7 @@ struct cdns_torrent_phy {
 	void __iomem *sd_base; /* SD0801 registers base */
 	u32 max_bit_rate; /* Maximum link bit rate to use (in Mbps) */
 	u32 dp_pll;
+	u32 protocol_bitmask;
 	struct reset_control *phy_rst;
 	struct reset_control *apb_rst;
 	struct device *dev;
@@ -2473,156 +2474,206 @@ int cdns_torrent_phy_configure_multilink(struct cdns_torrent_phy *cdns_phy)
 	enum cdns_torrent_phy_type phy_t1, phy_t2;
 	const struct cdns_reg_pairs *reg_pairs;
 	int i, j, node, mlane, num_lanes, ret;
+	struct device *dev = cdns_phy->dev;
 	enum cdns_torrent_ssc_mode ssc;
 	struct regmap *regmap;
-	u32 num_regs;
+	u32 num_regs, num_protocols, protocol;
 
-	/* Maximum 2 links (subnodes) are supported */
-	if (cdns_phy->nsubnodes != 2)
+	num_protocols = hweight32(cdns_phy->protocol_bitmask);
+	/* Maximum 2 protocols are supported */
+	if (num_protocols > 2) {
+		dev_err(dev, "at most 2 protocols are supported\n");
 		return -EINVAL;
+	}
+
+
+	/**
+	 * Get PHY types directly from subnodes if only 2 subnodes exist.
+	 * It is possible for phy_t1 to be the same as phy_t2 for special
+	 * configurations such as PCIe Multilink.
+	 */
+	if (cdns_phy->nsubnodes == 2) {
+		phy_t1 = cdns_phy->phys[0].phy_type;
+		phy_t2 = cdns_phy->phys[1].phy_type;
+	} else {
+		/**
+		 * Both PHY types / protocols should be unique.
+		 * If they are the same, it should be expressed with either
+		 * a) Single-Link (1 Sub-node) - handled via PHY APIs
+		 * OR
+		 * b) Double-Link (2 Sub-nodes) - handled above
+		 */
+		if (num_protocols != 2) {
+			dev_err(dev, "incorrect representation of link\n");
+			return -EINVAL;
+		}
 
-	phy_t1 = cdns_phy->phys[0].phy_type;
-	phy_t2 = cdns_phy->phys[1].phy_type;
+		phy_t1 = fns(cdns_phy->protocol_bitmask, 0);
+		phy_t2 = fns(cdns_phy->protocol_bitmask, 1);
+	}
 
 	/**
-	 * First configure the PHY for first link with phy_t1. Get the array
-	 * values as [phy_t1][phy_t2][ssc].
+	 * Configure all links with the protocol phy_t1 first followed by
+	 * configuring all links with the protocol phy_t2.
+	 *
+	 * When phy_t1 = phy_t2, it is a single protocol and configuration
+	 * is performed with a single iteration of the protocol and multiple
+	 * iterations over the sub-nodes (links).
+	 *
+	 * When phy_t1 != phy_t2, there are two protocols and configuration
+	 * is performed by iterating over all sub-nodes matching the first
+	 * protocol and configuring them first, followed by iterating over
+	 * all sub-nodes matching the second protocol and configuring them
+	 * next.
 	 */
-	for (node = 0; node < cdns_phy->nsubnodes; node++) {
-		if (node == 1) {
+	for (protocol = 0; protocol < num_protocols; protocol++) {
+		/**
+		 * For the case where num_protocols is 1,
+		 * phy_t1 = phy_t2 and the swap is unnecessary.
+		 *
+		 * Swapping phy_t1 and phy_t2 is only required when the
+		 * number of protocols is 2 and there are 2 or more links.
+		 */
+		if (protocol == 1) {
 			/**
-			 * If first link with phy_t1 is configured, then
-			 * configure the PHY for second link with phy_t2.
+			 * If first protocol with phy_t1 is configured, then
+			 * configure the PHY for second protocol with phy_t2.
 			 * Get the array values as [phy_t2][phy_t1][ssc].
 			 */
 			swap(phy_t1, phy_t2);
 			swap(ref_clk, ref_clk1);
 		}
 
-		mlane = cdns_phy->phys[node].mlane;
-		ssc = cdns_phy->phys[node].ssc_mode;
-		num_lanes = cdns_phy->phys[node].num_lanes;
+		for (node = 0; node < cdns_phy->nsubnodes; node++) {
+			if (cdns_phy->phys[node].phy_type != phy_t1)
+				continue;
 
-		/**
-		 * PHY configuration specific registers:
-		 * link_cmn_vals depend on combination of PHY types being
-		 * configured and are common for both PHY types, so array
-		 * values should be same for [phy_t1][phy_t2][ssc] and
-		 * [phy_t2][phy_t1][ssc].
-		 * xcvr_diag_vals also depend on combination of PHY types
-		 * being configured, but these can be different for particular
-		 * PHY type and are per lane.
-		 */
-		link_cmn_vals = cdns_torrent_get_tbl_vals(&init_data->link_cmn_vals_tbl,
-							  CLK_ANY, CLK_ANY,
-							  phy_t1, phy_t2, ANY_SSC);
-		if (link_cmn_vals) {
-			reg_pairs = link_cmn_vals->reg_pairs;
-			num_regs = link_cmn_vals->num_regs;
-			regmap = cdns_phy->regmap_common_cdb;
+			mlane = cdns_phy->phys[node].mlane;
+			ssc = cdns_phy->phys[node].ssc_mode;
+			num_lanes = cdns_phy->phys[node].num_lanes;
 
 			/**
-			 * First array value in link_cmn_vals must be of
-			 * PHY_PLL_CFG register
+			 * PHY configuration specific registers:
+			 * link_cmn_vals depend on combination of PHY types being
+			 * configured and are common for both PHY types, so array
+			 * values should be same for [phy_t1][phy_t2][ssc] and
+			 * [phy_t2][phy_t1][ssc].
+			 * xcvr_diag_vals also depend on combination of PHY types
+			 * being configured, but these can be different for particular
+			 * PHY type and are per lane.
 			 */
-			regmap_field_write(cdns_phy->phy_pll_cfg,
-					   reg_pairs[0].val);
+			link_cmn_vals = cdns_torrent_get_tbl_vals(&init_data->link_cmn_vals_tbl,
+								  CLK_ANY, CLK_ANY,
+								  phy_t1, phy_t2, ANY_SSC);
+			if (link_cmn_vals) {
+				reg_pairs = link_cmn_vals->reg_pairs;
+				num_regs = link_cmn_vals->num_regs;
+				regmap = cdns_phy->regmap_common_cdb;
+
+				/**
+				 * First array value in link_cmn_vals must be of
+				 * PHY_PLL_CFG register
+				 */
+				regmap_field_write(cdns_phy->phy_pll_cfg,
+						   reg_pairs[0].val);
+
+				for (i = 1; i < num_regs; i++)
+					regmap_write(regmap, reg_pairs[i].off,
+						     reg_pairs[i].val);
+			}
 
-			for (i = 1; i < num_regs; i++)
-				regmap_write(regmap, reg_pairs[i].off,
-					     reg_pairs[i].val);
-		}
+			xcvr_diag_vals = cdns_torrent_get_tbl_vals(&init_data->xcvr_diag_vals_tbl,
+								   CLK_ANY, CLK_ANY,
+								   phy_t1, phy_t2, ANY_SSC);
+			if (xcvr_diag_vals) {
+				reg_pairs = xcvr_diag_vals->reg_pairs;
+				num_regs = xcvr_diag_vals->num_regs;
+				for (i = 0; i < num_lanes; i++) {
+					regmap = cdns_phy->regmap_tx_lane_cdb[i + mlane];
+					for (j = 0; j < num_regs; j++)
+						regmap_write(regmap, reg_pairs[j].off,
+							     reg_pairs[j].val);
+				}
+			}
 
-		xcvr_diag_vals = cdns_torrent_get_tbl_vals(&init_data->xcvr_diag_vals_tbl,
-							   CLK_ANY, CLK_ANY,
-							   phy_t1, phy_t2, ANY_SSC);
-		if (xcvr_diag_vals) {
-			reg_pairs = xcvr_diag_vals->reg_pairs;
-			num_regs = xcvr_diag_vals->num_regs;
-			for (i = 0; i < num_lanes; i++) {
-				regmap = cdns_phy->regmap_tx_lane_cdb[i + mlane];
-				for (j = 0; j < num_regs; j++)
-					regmap_write(regmap, reg_pairs[j].off,
-						     reg_pairs[j].val);
+			/* PHY PCS common registers configurations */
+			pcs_cmn_vals = cdns_torrent_get_tbl_vals(&init_data->pcs_cmn_vals_tbl,
+								 CLK_ANY, CLK_ANY,
+								 phy_t1, phy_t2, ANY_SSC);
+			if (pcs_cmn_vals) {
+				reg_pairs = pcs_cmn_vals->reg_pairs;
+				num_regs = pcs_cmn_vals->num_regs;
+				regmap = cdns_phy->regmap_phy_pcs_common_cdb;
+				for (i = 0; i < num_regs; i++)
+					regmap_write(regmap, reg_pairs[i].off,
+						     reg_pairs[i].val);
 			}
-		}
 
-		/* PHY PCS common registers configurations */
-		pcs_cmn_vals = cdns_torrent_get_tbl_vals(&init_data->pcs_cmn_vals_tbl,
-							 CLK_ANY, CLK_ANY,
-							 phy_t1, phy_t2, ANY_SSC);
-		if (pcs_cmn_vals) {
-			reg_pairs = pcs_cmn_vals->reg_pairs;
-			num_regs = pcs_cmn_vals->num_regs;
-			regmap = cdns_phy->regmap_phy_pcs_common_cdb;
-			for (i = 0; i < num_regs; i++)
-				regmap_write(regmap, reg_pairs[i].off,
-					     reg_pairs[i].val);
-		}
+			/* PHY PMA common registers configurations */
+			phy_pma_cmn_vals =
+				cdns_torrent_get_tbl_vals(&init_data->phy_pma_cmn_vals_tbl,
+							  CLK_ANY, CLK_ANY, phy_t1, phy_t2,
+							  ANY_SSC);
+			if (phy_pma_cmn_vals) {
+				reg_pairs = phy_pma_cmn_vals->reg_pairs;
+				num_regs = phy_pma_cmn_vals->num_regs;
+				regmap = cdns_phy->regmap_phy_pma_common_cdb;
+				for (i = 0; i < num_regs; i++)
+					regmap_write(regmap, reg_pairs[i].off,
+						     reg_pairs[i].val);
+			}
 
-		/* PHY PMA common registers configurations */
-		phy_pma_cmn_vals = cdns_torrent_get_tbl_vals(&init_data->phy_pma_cmn_vals_tbl,
-							     CLK_ANY, CLK_ANY,
-							     phy_t1, phy_t2, ANY_SSC);
-		if (phy_pma_cmn_vals) {
-			reg_pairs = phy_pma_cmn_vals->reg_pairs;
-			num_regs = phy_pma_cmn_vals->num_regs;
-			regmap = cdns_phy->regmap_phy_pma_common_cdb;
-			for (i = 0; i < num_regs; i++)
-				regmap_write(regmap, reg_pairs[i].off,
-					     reg_pairs[i].val);
-		}
+			/* PMA common registers configurations */
+			cmn_vals = cdns_torrent_get_tbl_vals(&init_data->cmn_vals_tbl,
+							     ref_clk, ref_clk1,
+							     phy_t1, phy_t2, ssc);
+			if (cmn_vals) {
+				reg_pairs = cmn_vals->reg_pairs;
+				num_regs = cmn_vals->num_regs;
+				regmap = cdns_phy->regmap_common_cdb;
+				for (i = 0; i < num_regs; i++)
+					regmap_write(regmap, reg_pairs[i].off,
+						     reg_pairs[i].val);
+			}
 
-		/* PMA common registers configurations */
-		cmn_vals = cdns_torrent_get_tbl_vals(&init_data->cmn_vals_tbl,
-						     ref_clk, ref_clk1,
-						     phy_t1, phy_t2, ssc);
-		if (cmn_vals) {
-			reg_pairs = cmn_vals->reg_pairs;
-			num_regs = cmn_vals->num_regs;
-			regmap = cdns_phy->regmap_common_cdb;
-			for (i = 0; i < num_regs; i++)
-				regmap_write(regmap, reg_pairs[i].off,
-					     reg_pairs[i].val);
-		}
+			/* PMA TX lane registers configurations */
+			tx_ln_vals = cdns_torrent_get_tbl_vals(&init_data->tx_ln_vals_tbl,
+							       ref_clk, ref_clk1,
+							       phy_t1, phy_t2, ssc);
+			if (tx_ln_vals) {
+				reg_pairs = tx_ln_vals->reg_pairs;
+				num_regs = tx_ln_vals->num_regs;
+				for (i = 0; i < num_lanes; i++) {
+					regmap = cdns_phy->regmap_tx_lane_cdb[i + mlane];
+					for (j = 0; j < num_regs; j++)
+						regmap_write(regmap, reg_pairs[j].off,
+							     reg_pairs[j].val);
+				}
+			}
 
-		/* PMA TX lane registers configurations */
-		tx_ln_vals = cdns_torrent_get_tbl_vals(&init_data->tx_ln_vals_tbl,
-						       ref_clk, ref_clk1,
-						       phy_t1, phy_t2, ssc);
-		if (tx_ln_vals) {
-			reg_pairs = tx_ln_vals->reg_pairs;
-			num_regs = tx_ln_vals->num_regs;
-			for (i = 0; i < num_lanes; i++) {
-				regmap = cdns_phy->regmap_tx_lane_cdb[i + mlane];
-				for (j = 0; j < num_regs; j++)
-					regmap_write(regmap, reg_pairs[j].off,
-						     reg_pairs[j].val);
+			/* PMA RX lane registers configurations */
+			rx_ln_vals = cdns_torrent_get_tbl_vals(&init_data->rx_ln_vals_tbl,
+							       ref_clk, ref_clk1,
+							       phy_t1, phy_t2, ssc);
+			if (rx_ln_vals) {
+				reg_pairs = rx_ln_vals->reg_pairs;
+				num_regs = rx_ln_vals->num_regs;
+				for (i = 0; i < num_lanes; i++) {
+					regmap = cdns_phy->regmap_rx_lane_cdb[i + mlane];
+					for (j = 0; j < num_regs; j++)
+						regmap_write(regmap, reg_pairs[j].off,
+							     reg_pairs[j].val);
+				}
 			}
-		}
 
-		/* PMA RX lane registers configurations */
-		rx_ln_vals = cdns_torrent_get_tbl_vals(&init_data->rx_ln_vals_tbl,
-						       ref_clk, ref_clk1,
-						       phy_t1, phy_t2, ssc);
-		if (rx_ln_vals) {
-			reg_pairs = rx_ln_vals->reg_pairs;
-			num_regs = rx_ln_vals->num_regs;
-			for (i = 0; i < num_lanes; i++) {
-				regmap = cdns_phy->regmap_rx_lane_cdb[i + mlane];
-				for (j = 0; j < num_regs; j++)
-					regmap_write(regmap, reg_pairs[j].off,
-						     reg_pairs[j].val);
+			if (phy_t1 == TYPE_DP) {
+				ret = cdns_torrent_dp_get_pll(cdns_phy, phy_t2);
+				if (ret)
+					return ret;
 			}
-		}
 
-		if (phy_t1 == TYPE_DP) {
-			ret = cdns_torrent_dp_get_pll(cdns_phy, phy_t2);
-			if (ret)
-				return ret;
+			reset_control_deassert(cdns_phy->phys[node].lnk_rst);
 		}
-
-		reset_control_deassert(cdns_phy->phys[node].lnk_rst);
 	}
 
 	/* Take the PHY out of reset */
@@ -2826,6 +2877,7 @@ static int cdns_torrent_phy_probe(struct platform_device *pdev)
 	dev_set_drvdata(dev, cdns_phy);
 	cdns_phy->dev = dev;
 	cdns_phy->init_data = data;
+	cdns_phy->protocol_bitmask = 0;
 
 	cdns_phy->sd_base = devm_platform_ioremap_resource(pdev, 0);
 	if (IS_ERR(cdns_phy->sd_base))
@@ -3010,6 +3062,7 @@ static int cdns_torrent_phy_probe(struct platform_device *pdev)
 		}
 
 		cdns_phy->phys[node].phy = gphy;
+		cdns_phy->protocol_bitmask |= BIT(cdns_phy->phys[node].phy_type);
 		phy_set_drvdata(gphy, &cdns_phy->phys[node]);
 
 		node++;