phy: qcom-qmp: Utilize fully-specified DT registers

Utilize the newly fixed up DT bindings to get the tx2 and rx2 register
regions for the second lane of dual-lane PHYs. Before this change,
the driver was simply using lane one's register region and adding
0x400, which reached well beyond the DT-specified register
allocation. This would have been a crash were it not for the page size
on ARM64. Fix the driver not to rely on the magic of virtual memory by
using the newly specified DT register regions for tx2 and rx2.

In order to support existing device trees, this change also contains a
fallback mode for when those new register regions don't exist, which
reverts to the original behavior of overreaching and prints a complaint.

Signed-off-by: Evan Green <[e-mail]>
Reviewed-by: Douglas Anderson <[e-mail]>
Signed-off-by: Kishon Vijay Abraham I <[e-mail]>

drivers/phy/qualcomm/phy-qcom-qmp.c

···
 
 #define MAX_PROP_NAME				32
 
+/* Define the assumed distance between lanes for underspecified device trees. */
+#define QMP_PHY_LEGACY_LANE_STRIDE		0x400
+
 struct qmp_phy_init_tbl {
 	unsigned int offset;
 	unsigned int val;
···
 	bool has_phy_dp_com_ctrl;
 	/* true, if PHY has secondary tx/rx lanes to be configured */
 	bool is_dual_lane_phy;
-	/* Register offset of secondary tx/rx lanes for USB DP combo PHY */
-	unsigned int tx_b_lane_offset;
-	unsigned int rx_b_lane_offset;
 
 	/* true, if PCS block has no separate SW_RESET register */
 	bool no_pcs_sw_reset;
···
  * @tx: iomapped memory space for lane's tx
  * @rx: iomapped memory space for lane's rx
  * @pcs: iomapped memory space for lane's pcs
+ * @tx2: iomapped memory space for second lane's tx (in dual lane PHYs)
+ * @rx2: iomapped memory space for second lane's rx (in dual lane PHYs)
  * @pcs_misc: iomapped memory space for lane's pcs_misc
  * @pipe_clk: pipe lock
  * @index: lane index
···
 	void __iomem *tx;
 	void __iomem *rx;
 	void __iomem *pcs;
+	void __iomem *tx2;
+	void __iomem *rx2;
 	void __iomem *pcs_misc;
 	struct clk *pipe_clk;
 	unsigned int index;
···
 
 	.has_phy_dp_com_ctrl	= true,
 	.is_dual_lane_phy	= true,
-	.tx_b_lane_offset	= 0x400,
-	.rx_b_lane_offset	= 0x400,
 };
 
 static const struct qmp_phy_cfg qmp_v3_usb3_uniphy_cfg = {
···
 	.mask_pcs_ready		= PCS_READY,
 
 	.is_dual_lane_phy	= true,
-	.tx_b_lane_offset	= 0x400,
-	.rx_b_lane_offset	= 0x400,
-
 	.no_pcs_sw_reset	= true,
 };
 
···
 	qcom_qmp_phy_configure(tx, cfg->regs, cfg->tx_tbl, cfg->tx_tbl_num);
 	/* Configuration for other LANE for USB-DP combo PHY */
 	if (cfg->is_dual_lane_phy)
-		qcom_qmp_phy_configure(tx + cfg->tx_b_lane_offset, cfg->regs,
+		qcom_qmp_phy_configure(qphy->tx2, cfg->regs,
 				       cfg->tx_tbl, cfg->tx_tbl_num);
 
 	qcom_qmp_phy_configure(rx, cfg->regs, cfg->rx_tbl, cfg->rx_tbl_num);
 	if (cfg->is_dual_lane_phy)
-		qcom_qmp_phy_configure(rx + cfg->rx_b_lane_offset, cfg->regs,
+		qcom_qmp_phy_configure(qphy->rx2, cfg->regs,
 				       cfg->rx_tbl, cfg->rx_tbl_num);
 
 	qcom_qmp_phy_configure(pcs, cfg->regs, cfg->pcs_tbl, cfg->pcs_tbl_num);
···
 
 	/*
 	 * Get memory resources for each phy lane:
-	 * Resources are indexed as: tx -> 0; rx -> 1; pcs -> 2; and
-	 * pcs_misc (optional) -> 3.
+	 * Resources are indexed as: tx -> 0; rx -> 1; pcs -> 2.
+	 * For dual lane PHYs: tx2 -> 3, rx2 -> 4, pcs_misc (optional) -> 5
+	 * For single lane PHYs: pcs_misc (optional) -> 3.
 	 */
 	qphy->tx = of_iomap(np, 0);
 	if (!qphy->tx)
···
 	if (!qphy->pcs)
 		return -ENOMEM;
 
-	qphy->pcs_misc = of_iomap(np, 3);
+	/*
+	 * If this is a dual-lane PHY, then there should be registers for the
+	 * second lane. Some old device trees did not specify this, so fall
+	 * back to old legacy behavior of assuming they can be reached at an
+	 * offset from the first lane.
+	 */
+	if (qmp->cfg->is_dual_lane_phy) {
+		qphy->tx2 = of_iomap(np, 3);
+		qphy->rx2 = of_iomap(np, 4);
+		if (!qphy->tx2 || !qphy->rx2) {
+			dev_warn(dev,
+				 "Underspecified device tree, falling back to legacy register regions\n");
+
+			/* In the old version, pcs_misc is at index 3. */
+			qphy->pcs_misc = qphy->tx2;
+			qphy->tx2 = qphy->tx + QMP_PHY_LEGACY_LANE_STRIDE;
+			qphy->rx2 = qphy->rx + QMP_PHY_LEGACY_LANE_STRIDE;
+
+		} else {
+			qphy->pcs_misc = of_iomap(np, 5);
+		}
+
+	} else {
+		qphy->pcs_misc = of_iomap(np, 3);
+	}
+
 	if (!qphy->pcs_misc)
 		dev_vdbg(dev, "PHY pcs_misc-reg not used\n");