[PATCH v3 phy-next 11/16] phy: lynx-28g: add support for big endian register maps

[Vladimir Oltean]

Some 10G Lynx SerDes blocks are big endian and require byte swapping
because the CPUs are little endian armv8 (LS1046A). Parse the
"big-endian" device tree property, and modify the base lynx_read() and
lynx_write() accessors to test this property before issuing either the
ioread32() or ioread32be() variants (as per
Documentation/driver-api/device-io.rst).

All other accessors - lynx_rmw(), lynx_lane_read(), lynx_lane_write(),
lynx_lane_rmw(), lynx_pll_read() - need to go through these endian-aware
helpers.

Signed-off-by: Vladimir Oltean <vladimir.oltean at nxp.com>
---
v2->v3: none
v1->v2:
- none. Deliberately ignoring this Sashiko feedback:
  https://lore.kernel.org/linux-phy/20260529120005.icj44ffdvdk25fjm@skbuf/
---
 drivers/phy/freescale/phy-fsl-lynx-core.c |  1 +
 drivers/phy/freescale/phy-fsl-lynx-core.h | 36 ++++++++++++++++-------
 2 files changed, 27 insertions(+), 10 deletions(-)

diff --git a/drivers/phy/freescale/phy-fsl-lynx-core.c b/drivers/phy/freescale/phy-fsl-lynx-core.c
index 3fb89bb4b0d6..226b2af2b599 100644
--- a/drivers/phy/freescale/phy-fsl-lynx-core.c
+++ b/drivers/phy/freescale/phy-fsl-lynx-core.c
@@ -295,6 +295,7 @@ int lynx_probe(struct platform_device *pdev, const struct lynx_info *info,
 
 	priv->dev = dev;
 	priv->info = info;
+	priv->big_endian = device_property_read_bool(dev, "big-endian");
 	dev_set_drvdata(dev, priv);
 	spin_lock_init(&priv->pcc_lock);
 	INIT_DELAYED_WORK(&priv->cdr_check, lynx_cdr_lock_check);
diff --git a/drivers/phy/freescale/phy-fsl-lynx-core.h b/drivers/phy/freescale/phy-fsl-lynx-core.h
index e8b280cc9b38..d82e529fa65a 100644
--- a/drivers/phy/freescale/phy-fsl-lynx-core.h
+++ b/drivers/phy/freescale/phy-fsl-lynx-core.h
@@ -58,36 +58,52 @@ struct lynx_priv {
 	 * like PCCn
 	 */
 	spinlock_t pcc_lock;
+	bool big_endian;
 	struct lynx_pll pll[LYNX_NUM_PLL];
 	struct lynx_lane *lane;
 
 	struct delayed_work cdr_check;
 };
 
+static inline u32 lynx_read(struct lynx_priv *priv, unsigned long off)
+{
+	void __iomem *reg = priv->base + off;
+
+	if (priv->big_endian)
+		return ioread32be(reg);
+
+	return ioread32(reg);
+}
+
+static inline void lynx_write(struct lynx_priv *priv, unsigned long off, u32 val)
+{
+	void __iomem *reg = priv->base + off;
+
+	if (priv->big_endian)
+		return iowrite32be(val, reg);
+
+	return iowrite32(val, reg);
+}
+
 static inline void lynx_rmw(struct lynx_priv *priv, unsigned long off, u32 val,
 			    u32 mask)
 {
-	void __iomem *reg = priv->base + off;
 	u32 orig, tmp;
 
-	orig = ioread32(reg);
+	orig = lynx_read(priv, off);
 	tmp = orig & ~mask;
 	tmp |= val;
-	iowrite32(tmp, reg);
+	lynx_write(priv, off, tmp);
 }
 
-#define lynx_read(priv, off) \
-	ioread32((priv)->base + (off))
-#define lynx_write(priv, off, val) \
-	iowrite32(val, (priv)->base + (off))
 #define lynx_lane_rmw(lane, reg, val, mask)	\
 	lynx_rmw((lane)->priv, reg(lane->id), val, mask)
 #define lynx_lane_read(lane, reg)			\
-	ioread32((lane)->priv->base + reg((lane)->id))
+	lynx_read((lane)->priv, reg((lane)->id))
 #define lynx_lane_write(lane, reg, val)		\
-	iowrite32(val, (lane)->priv->base + reg((lane)->id))
+	lynx_write((lane)->priv, reg((lane)->id), val)
 #define lynx_pll_read(pll, reg)			\
-	ioread32((pll)->priv->base + reg((pll)->id))
+	lynx_read((pll)->priv, reg((pll)->id))
 
 int lynx_probe(struct platform_device *pdev, const struct lynx_info *info,
 	       const struct phy_ops *phy_ops);
-- 
2.34.1