[RFC PATCH 2/2] regmap: mdio: Add clause-45 support

[Sander Vanheule]

Modern ethernet phys support the so-called clause-45 register access
mode, which allows for register address widths of 16 bit.

Also allow for 16-bit register address widths, and return a regmap for
clause-45 access in that case.

Signed-off-by: Sander Vanheule <sander@xxxxxxxxxxxxx>
---
 drivers/base/regmap/regmap-mdio.c | 70 ++++++++++++++++++++++++-------
 1 file changed, 56 insertions(+), 14 deletions(-)

diff --git a/drivers/base/regmap/regmap-mdio.c b/drivers/base/regmap/regmap-mdio.c
index aee34bf2400e..cfb23afb19eb 100644
--- a/drivers/base/regmap/regmap-mdio.c
+++ b/drivers/base/regmap/regmap-mdio.c
@@ -7,13 +7,14 @@
 
 #define REGVAL_MASK		GENMASK(15, 0)
 #define REGNUM_C22_MASK		GENMASK(4, 0)
+/* Clause-45 mask includes the device type (5 bit) and actual register number (16 bit) */
+#define REGNUM_C45_MASK		GENMASK(20, 0)
 
-static int regmap_mdio_read(void *context, unsigned int reg, unsigned int *val)
+static int regmap_mdio_read(struct mdio_device *mdio_dev, u32 reg, unsigned int *val)
 {
-	struct mdio_device *mdio_dev = context;
 	int ret;
 
-	ret = mdiobus_read(mdio_dev->bus, mdio_dev->addr, reg & REGNUM_C22_MASK);
+	ret = mdiobus_read(mdio_dev->bus, mdio_dev->addr, reg);
 	if (ret < 0)
 		return ret;
 
@@ -21,27 +22,63 @@ static int regmap_mdio_read(void *context, unsigned int reg, unsigned int *val)
 	return 0;
 }
 
-static int regmap_mdio_write(void *context, unsigned int reg, unsigned int val)
+static int regmap_mdio_write(struct mdio_device *mdio_dev, u32 reg, unsigned int val)
+{
+	return mdiobus_write(mdio_dev->bus, mdio_dev->addr, reg, val);
+}
+
+static int regmap_mdio_c22_read(void *context, unsigned int reg, unsigned int *val)
+{
+	struct mdio_device *mdio_dev = context;
+
+	return regmap_mdio_read(mdio_dev, reg & REGNUM_C22_MASK, val);
+}
+
+static int regmap_mdio_c22_write(void *context, unsigned int reg, unsigned int val)
 {
 	struct mdio_device *mdio_dev = context;
 
-	return mdiobus_write(mdio_dev->bus, mdio_dev->addr, reg & REGNUM_C22_MASK, val);
+	return regmap_mdio_write(mdio_dev, reg & REGNUM_C22_MASK, val);
 }
 
-static const struct regmap_bus regmap_mdio_bus = {
-	.reg_write = regmap_mdio_write,
-	.reg_read = regmap_mdio_read,
+static const struct regmap_bus regmap_mdio_c22_bus = {
+	.reg_write = regmap_mdio_c22_write,
+	.reg_read = regmap_mdio_c22_read,
+};
+
+static int regmap_mdio_c45_read(void *context, unsigned int reg, unsigned int *val)
+{
+	struct mdio_device *mdio_dev = context;
+
+	return regmap_mdio_read(mdio_dev, MII_ADDR_C45 | (reg & REGNUM_C45_MASK), val);
+}
+
+static int regmap_mdio_c45_write(void *context, unsigned int reg, unsigned int val)
+{
+	struct mdio_device *mdio_dev = context;
+
+	return regmap_mdio_write(mdio_dev, MII_ADDR_C45 | (reg & REGNUM_C45_MASK), val);
+}
+
+static const struct regmap_bus regmap_mdio_c45_bus = {
+	.reg_write = regmap_mdio_c45_write,
+	.reg_read = regmap_mdio_c45_read,
 };
 
 struct regmap *__regmap_init_mdio(struct mdio_device *mdio_dev,
 	const struct regmap_config *config, struct lock_class_key *lock_key,
 	const char *lock_name)
 {
-	if (config->reg_bits != 5 || config->val_bits != 16)
+	struct regmap_bus *bus;
+
+	if (config->reg_bits == 5 && config->val_bits == 16)
+		bus = &regmap_mdio_c22_bus;
+	else if (config->reg_bits == 21 && config->val_bits == 16)
+		bus = &regmap_mdio_c45_bus;
+	else
 		return ERR_PTR(-EOPNOTSUPP);
 
-	return __regmap_init(&mdio_dev->dev, &regmap_mdio_bus, mdio_dev, config,
-		lock_key, lock_name);
+	return __regmap_init(&mdio_dev->dev, bus, mdio_dev, config, lock_key, lock_name);
 }
 EXPORT_SYMBOL_GPL(__regmap_init_mdio);
 
@@ -49,11 +86,16 @@ struct regmap *__devm_regmap_init_mdio(struct mdio_device *mdio_dev,
 	const struct regmap_config *config, struct lock_class_key *lock_key,
 	const char *lock_name)
 {
-	if (config->reg_bits != 5 || config->val_bits != 16)
+	const struct regmap_bus *bus;
+
+	if (config->reg_bits == 5 && config->val_bits == 16)
+		bus = &regmap_mdio_c22_bus;
+	else if (config->reg_bits == 21 && config->val_bits == 16)
+		bus = &regmap_mdio_c45_bus;
+	else
 		return ERR_PTR(-EOPNOTSUPP);
 
-	return __devm_regmap_init(&mdio_dev->dev, &regmap_mdio_bus, mdio_dev,
-		config, lock_key, lock_name);
+	return __devm_regmap_init(&mdio_dev->dev, bus, mdio_dev, config, lock_key, lock_name);
 }
 EXPORT_SYMBOL_GPL(__devm_regmap_init_mdio);
 
-- 
2.31.1