diff mbox series

[RFC,net-next,v3,03/15] net: dsa: mt7530: use regmap to access switch register space

Message ID 754322262cd754aee5916954b8e651989b229a09.1680105013.git.daniel@makrotopia.org
State New
Headers
Series net: dsa: add support for MT7988 |

Commit Message

Daniel Golle March 29, 2023, 3:57 p.m. UTC 
  Use regmap API to access the switch register space.

Signed-off-by: Daniel Golle <daniel@makrotopia.org>
---
 drivers/net/dsa/mt7530.c | 88 +++++++++++++++++++++++++---------------
 drivers/net/dsa/mt7530.h |  2 +
 2 files changed, 58 insertions(+), 32 deletions(-)

Comments

Andrew Lunn March 29, 2023, 4:24 p.m. UTC | #1 
Thanks for splitting this patchset up. This is much easier to review.

> +static u32
> +mt7530_mii_read(struct mt7530_priv *priv, u32 reg)
> +{
> +	int ret;
> +	u32 val;
> +
> +	ret = regmap_read(priv->regmap, reg, &val);
> +	if (ret) {
> +		dev_err(priv->dev,
> +			"failed to read mt7530 register\n");
> +		return ret;

This is a u32 function. ret should be negative on error, which is
going to be turned positive in order to return a u32. So you probably
want to make this an int function.

     Andrew
Daniel Golle March 29, 2023, 6:33 p.m. UTC | #2 
On Wed, Mar 29, 2023 at 06:24:21PM +0200, Andrew Lunn wrote:
> Thanks for splitting this patchset up. This is much easier to review.
> 
> > +static u32
> > +mt7530_mii_read(struct mt7530_priv *priv, u32 reg)
> > +{
> > +	int ret;
> > +	u32 val;
> > +
> > +	ret = regmap_read(priv->regmap, reg, &val);
> > +	if (ret) {
> > +		dev_err(priv->dev,
> > +			"failed to read mt7530 register\n");
> > +		return ret;
> 
> This is a u32 function. ret should be negative on error, which is
> going to be turned positive in order to return a u32. So you probably
> want to make this an int function.

This is a pre-existing flaw in the code. As we are accessing 32-bit
registers there has just never been any meaningful error handling.
I guess the correct solution would be to not use the return value only
to indicate success or error, and use an additional u32* parameter for
the read value.

However, I was hestitating to convert all the calls (they are many) to
follow that improved paradigm.

Should I?
Andrew Lunn March 29, 2023, 7:35 p.m. UTC | #3 
On Wed, Mar 29, 2023 at 07:33:17PM +0100, Daniel Golle wrote:
> On Wed, Mar 29, 2023 at 06:24:21PM +0200, Andrew Lunn wrote:
> > Thanks for splitting this patchset up. This is much easier to review.
> > 
> > > +static u32
> > > +mt7530_mii_read(struct mt7530_priv *priv, u32 reg)
> > > +{
> > > +	int ret;
> > > +	u32 val;
> > > +
> > > +	ret = regmap_read(priv->regmap, reg, &val);
> > > +	if (ret) {
> > > +		dev_err(priv->dev,
> > > +			"failed to read mt7530 register\n");
> > > +		return ret;
> > 
> > This is a u32 function. ret should be negative on error, which is
> > going to be turned positive in order to return a u32. So you probably
> > want to make this an int function.
> 
> This is a pre-existing flaw in the code. As we are accessing 32-bit
> registers there has just never been any meaningful error handling.

O.K. At least i would not return the negative error code. Return 0, or
0xdeadbeef or something. And consider adding a WARN_ON_ONCE() so it is very loud
when it goes wrong.

> I guess the correct solution would be to not use the return value only
> to indicate success or error, and use an additional u32* parameter for
> the read value.

Yes, that is what mv88e6xxx does.

> However, I was hestitating to convert all the calls (they are many) to
> follow that improved paradigm.

Yes, leave that for another time.

     Andrew
diff mbox series

Patch

diff --git a/drivers/net/dsa/mt7530.c b/drivers/net/dsa/mt7530.c
index deb0b338b22c2..fffeac8d34855 100644
--- a/drivers/net/dsa/mt7530.c
+++ b/drivers/net/dsa/mt7530.c
@@ -183,9 +183,9 @@  core_clear(struct mt7530_priv *priv, u32 reg, u32 val)
 }
 
 static int
-mt7530_mii_write(struct mt7530_priv *priv, u32 reg, u32 val)
+mt7530_regmap_write(void *context, unsigned int reg, unsigned int val)
 {
-	struct mii_bus *bus = priv->bus;
+	struct mii_bus *bus = context;
 	u16 page, r, lo, hi;
 	int ret;
 
@@ -197,24 +197,33 @@  mt7530_mii_write(struct mt7530_priv *priv, u32 reg, u32 val)
 	/* MT7530 uses 31 as the pseudo port */
 	ret = bus->write(bus, 0x1f, 0x1f, page);
 	if (ret < 0)
-		goto err;
+		return ret;
 
 	ret = bus->write(bus, 0x1f, r,  lo);
 	if (ret < 0)
-		goto err;
+		return ret;
 
 	ret = bus->write(bus, 0x1f, 0x10, hi);
-err:
+	return ret;
+}
+
+static int
+mt7530_mii_write(struct mt7530_priv *priv, u32 reg, u32 val)
+{
+	int ret;
+
+	ret = regmap_write(priv->regmap, reg, val);
+
 	if (ret < 0)
-		dev_err(&bus->dev,
+		dev_err(priv->dev,
 			"failed to write mt7530 register\n");
 	return ret;
 }
 
-static u32
-mt7530_mii_read(struct mt7530_priv *priv, u32 reg)
+static int
+mt7530_regmap_read(void *context, unsigned int reg, unsigned int *val)
 {
-	struct mii_bus *bus = priv->bus;
+	struct mii_bus *bus = context;
 	u16 page, r, lo, hi;
 	int ret;
 
@@ -223,16 +232,31 @@  mt7530_mii_read(struct mt7530_priv *priv, u32 reg)
 
 	/* MT7530 uses 31 as the pseudo port */
 	ret = bus->write(bus, 0x1f, 0x1f, page);
-	if (ret < 0) {
-		dev_err(&bus->dev,
-			"failed to read mt7530 register\n");
+	if (ret < 0)
 		return ret;
-	}
 
 	lo = bus->read(bus, 0x1f, r);
 	hi = bus->read(bus, 0x1f, 0x10);
 
-	return (hi << 16) | (lo & 0xffff);
+	*val = (hi << 16) | (lo & 0xffff);
+
+	return 0;
+}
+
+static u32
+mt7530_mii_read(struct mt7530_priv *priv, u32 reg)
+{
+	int ret;
+	u32 val;
+
+	ret = regmap_read(priv->regmap, reg, &val);
+	if (ret) {
+		dev_err(priv->dev,
+			"failed to read mt7530 register\n");
+		return ret;
+	}
+
+	return val;
 }
 
 static void
@@ -2895,22 +2919,6 @@  static const struct phylink_pcs_ops mt7530_pcs_ops = {
 	.pcs_an_restart = mt7530_pcs_an_restart,
 };
 
-static int mt7530_regmap_read(void *context, unsigned int reg, unsigned int *val)
-{
-	struct mt7530_priv *priv = context;
-
-	*val = mt7530_mii_read(priv, reg);
-	return 0;
-};
-
-static int mt7530_regmap_write(void *context, unsigned int reg, unsigned int val)
-{
-	struct mt7530_priv *priv = context;
-
-	mt7530_mii_write(priv, reg, val);
-	return 0;
-};
-
 static void
 mt7530_mdio_regmap_lock(void *mdio_lock)
 {
@@ -2923,7 +2931,7 @@  mt7530_mdio_regmap_unlock(void *mdio_lock)
 	mutex_unlock(mdio_lock);
 }
 
-static const struct regmap_bus mt7531_regmap_bus = {
+static const struct regmap_bus mt7530_regmap_bus = {
 	.reg_write = mt7530_regmap_write,
 	.reg_read = mt7530_regmap_read,
 };
@@ -2956,7 +2964,7 @@  mt7531_create_sgmii(struct mt7530_priv *priv)
 		mt7531_pcs_config[i]->lock_arg = &priv->bus->mdio_lock;
 
 		regmap = devm_regmap_init(priv->dev,
-					  &mt7531_regmap_bus, priv,
+					  &mt7530_regmap_bus, priv->bus,
 					  mt7531_pcs_config[i]);
 		if (IS_ERR(regmap)) {
 			ret = PTR_ERR(regmap);
@@ -3127,6 +3135,7 @@  MODULE_DEVICE_TABLE(of, mt7530_of_match);
 static int
 mt7530_probe(struct mdio_device *mdiodev)
 {
+	static struct regmap_config *regmap_config;
 	struct mt7530_priv *priv;
 	struct device_node *dn;
 
@@ -3206,6 +3215,21 @@  mt7530_probe(struct mdio_device *mdiodev)
 	mutex_init(&priv->reg_mutex);
 	dev_set_drvdata(&mdiodev->dev, priv);
 
+	regmap_config = devm_kzalloc(&mdiodev->dev, sizeof(*regmap_config),
+				     GFP_KERNEL);
+	if (!regmap_config)
+		return -ENOMEM;
+
+	regmap_config->reg_bits = 16;
+	regmap_config->val_bits = 32;
+	regmap_config->reg_stride = 4;
+	regmap_config->max_register = MT7530_CREV;
+	regmap_config->disable_locking = true;
+	priv->regmap = devm_regmap_init(priv->dev, &mt7530_regmap_bus,
+					priv->bus, regmap_config);
+	if (IS_ERR(priv->regmap))
+		return PTR_ERR(priv->regmap);
+
 	return dsa_register_switch(priv->ds);
 }
 
diff --git a/drivers/net/dsa/mt7530.h b/drivers/net/dsa/mt7530.h
index c5d29f3fc1d80..39aaca50961bd 100644
--- a/drivers/net/dsa/mt7530.h
+++ b/drivers/net/dsa/mt7530.h
@@ -754,6 +754,7 @@  struct mt753x_info {
  * @dev:		The device pointer
  * @ds:			The pointer to the dsa core structure
  * @bus:		The bus used for the device and built-in PHY
+ * @regmap:		The regmap instance representing all switch registers
  * @rstc:		The pointer to reset control used by MCM
  * @core_pwr:		The power supplied into the core
  * @io_pwr:		The power supplied into the I/O
@@ -774,6 +775,7 @@  struct mt7530_priv {
 	struct device		*dev;
 	struct dsa_switch	*ds;
 	struct mii_bus		*bus;
+	struct regmap		*regmap;
 	struct reset_control	*rstc;
 	struct regulator	*core_pwr;
 	struct regulator	*io_pwr;