net: phy: extend PHY package API to support multiple global address

Current API for PHY package are limited to single address to configure
global settings for the PHY package.

It was found that some PHY package (for example the qca807x, a PHY
package that is shipped with a bundle of 5 PHY) requires multiple PHY
address to configure global settings. An example scenario is a PHY that
have a dedicated PHY for PSGMII/serdes calibrarion and have a specific
PHY in the package where the global PHY mode is set and affects every
other PHY in the package.

Change the API in the following way:
- Change phy_package_join() to take the base addr of the PHY package
  instead of the global PHY addr.
- Make __/phy_package_write/read() require an additional arg that
  select what global PHY address to use by passing the offset from the
  base addr passed on phy_package_join().

Each user of this API is updated to follow this new implementation
following a pattern where an enum is defined to declare the offset of the
addr.

We also drop the check if shared is defined as any user of the
phy_package_read/write is expected to use phy_package_join first. Misuse
of this will correctly trigger a kernel panic for NULL pointer
exception.

Signed-off-by: Christian Marangi <ansuelsmth@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 42 insertions, 22 deletions

diff --git a/include/linux/phy.h b/include/linux/phy.h
index 4b13cc85c4f5..d653f660c39d 100644
--- a/include/linux/phy.h
+++ b/include/linux/phy.h
@@ -327,7 +327,8 @@ struct mdio_bus_stats {
 
 /**
  * struct phy_package_shared - Shared information in PHY packages
- * @addr: Common PHY address used to combine PHYs in one package
+ * @base_addr: Base PHY address of PHY package used to combine PHYs
+ *   in one package and for offset calculation of phy_package_read/write
  * @refcnt: Number of PHYs connected to this shared data
  * @flags: Initialization of PHY package
  * @priv_size: Size of the shared private data @priv
@@ -338,7 +339,7 @@ struct mdio_bus_stats {
  * phy_package_leave().
  */
 struct phy_package_shared {
-	u8 addr;
+	u8 base_addr;
 	refcount_t refcnt;
 	unsigned long flags;
 	size_t priv_size;
@@ -1976,10 +1977,10 @@ int phy_ethtool_get_link_ksettings(struct net_device *ndev,
 int phy_ethtool_set_link_ksettings(struct net_device *ndev,
 				   const struct ethtool_link_ksettings *cmd);
 int phy_ethtool_nway_reset(struct net_device *ndev);
-int phy_package_join(struct phy_device *phydev, int addr, size_t priv_size);
+int phy_package_join(struct phy_device *phydev, int base_addr, size_t priv_size);
 void phy_package_leave(struct phy_device *phydev);
 int devm_phy_package_join(struct device *dev, struct phy_device *phydev,
-			  int addr, size_t priv_size);
+			  int base_addr, size_t priv_size);
 
 int __init mdio_bus_init(void);
 void mdio_bus_exit(void);
@@ -2002,46 +2003,65 @@ int __phy_hwtstamp_set(struct phy_device *phydev,
 		       struct kernel_hwtstamp_config *config,
 		       struct netlink_ext_ack *extack);
 
-static inline int phy_package_read(struct phy_device *phydev, u32 regnum)
+static inline int phy_package_address(struct phy_device *phydev,
+				      unsigned int addr_offset)
 {
 	struct phy_package_shared *shared = phydev->shared;
+	u8 base_addr = shared->base_addr;
 
-	if (!shared)
+	if (addr_offset >= PHY_MAX_ADDR - base_addr)
 		return -EIO;
 
-	return mdiobus_read(phydev->mdio.bus, shared->addr, regnum);
+	/* we know that addr will be in the range 0..31 and thus the
+	 * implicit cast to a signed int is not a problem.
+	 */
+	return base_addr + addr_offset;
 }
 
-static inline int __phy_package_read(struct phy_device *phydev, u32 regnum)
+static inline int phy_package_read(struct phy_device *phydev,
+				   unsigned int addr_offset, u32 regnum)
 {
-	struct phy_package_shared *shared = phydev->shared;
+	int addr = phy_package_address(phydev, addr_offset);
 
-	if (!shared)
-		return -EIO;
+	if (addr < 0)
+		return addr;
+
+	return mdiobus_read(phydev->mdio.bus, addr, regnum);
+}
+
+static inline int __phy_package_read(struct phy_device *phydev,
+				     unsigned int addr_offset, u32 regnum)
+{
+	int addr = phy_package_address(phydev, addr_offset);
+
+	if (addr < 0)
+		return addr;
 
-	return __mdiobus_read(phydev->mdio.bus, shared->addr, regnum);
+	return __mdiobus_read(phydev->mdio.bus, addr, regnum);
 }
 
 static inline int phy_package_write(struct phy_device *phydev,
-				    u32 regnum, u16 val)
+				    unsigned int addr_offset, u32 regnum,
+				    u16 val)
 {
-	struct phy_package_shared *shared = phydev->shared;
+	int addr = phy_package_address(phydev, addr_offset);
 
-	if (!shared)
-		return -EIO;
+	if (addr < 0)
+		return addr;
 
-	return mdiobus_write(phydev->mdio.bus, shared->addr, regnum, val);
+	return mdiobus_write(phydev->mdio.bus, addr, regnum, val);
 }
 
 static inline int __phy_package_write(struct phy_device *phydev,
-				      u32 regnum, u16 val)
+				      unsigned int addr_offset, u32 regnum,
+				      u16 val)
 {
-	struct phy_package_shared *shared = phydev->shared;
+	int addr = phy_package_address(phydev, addr_offset);
 
-	if (!shared)
-		return -EIO;
+	if (addr < 0)
+		return addr;
 
-	return __mdiobus_write(phydev->mdio.bus, shared->addr, regnum, val);
+	return __mdiobus_write(phydev->mdio.bus, addr, regnum, val);
 }
 
 static inline bool __phy_package_set_once(struct phy_device *phydev,