Merge branch 'axiennet-mdio-bus-freq'

Andy Chiu says:

====================
net: axienet: Use a DT property to configure frequency of the MDIO bus

Some FPGA platforms have to set frequency of the MDIO bus lower than 2.5
MHz. Thus, we use a DT property, which is "clock-frequency", to work
with it at boot time. The default 2.5 MHz would be set if the property
is not pressent. Also, factor out mdio enable/disable functions due to
the api change since 253761a.

Changelog:
--- v5 ---
1. Make dt-binding patch prior to the implementation patch.
2. Disable mdio bus in error path.
3. Update description of some functions.
--- v4 ---
1. change MAX_MDIO_FREQ to DEFAULT_MDIO_FREQ as suggested by Andrew.
--- v3 RESEND ---
1. Repost the exact same patch again
--- v3 ---
1. Fix coding style, and make probing of the driver fail if MDC overflow
--- v2 ---
1. Use clock-frequency, as defined in mdio.yaml, to configure MDIO
   clock.
2. Only print out frequency if it is set to a non-standard value.
3. Reduce the scope of axienet_mdio_enable and remove
   axienet_mdio_disable because no one really uses it anymore.
====================

Signed-off-by: David S. Miller <davem@davemloft.net>

Documentation/devicetree/bindings/net/xilinx_axienet.txt

@@ -68,6 +68,8 @@ Optional properties:
  - mdio		: Child node for MDIO bus. Must be defined if PHY access is
 		  required through the core's MDIO interface (i.e. always,
 		  unless the PHY is accessed through a different bus).
+		  Non-standard MDIO bus frequency is supported via
+		  "clock-frequency", see mdio.yaml.
 
  - pcs-handle: 	  Phandle to the internal PCS/PMA PHY in SGMII or 1000Base-X
 		  modes, where "pcs-handle" should be used to point

drivers/net/ethernet/xilinx/xilinx_axienet.h

@@ -611,8 +611,6 @@ static inline void axienet_dma_out_addr(struct axienet_local *lp, off_t reg,
 #endif /* CONFIG_64BIT */
 
 /* Function prototypes visible in xilinx_axienet_mdio.c for other files */
-int axienet_mdio_enable(struct axienet_local *lp);
-void axienet_mdio_disable(struct axienet_local *lp);
 int axienet_mdio_setup(struct axienet_local *lp);
 void axienet_mdio_teardown(struct axienet_local *lp);
 

drivers/net/ethernet/xilinx/xilinx_axienet_mdio.c

@@ -17,7 +17,7 @@
 
 #include "xilinx_axienet.h"
 
-#define MAX_MDIO_FREQ		2500000 /* 2.5 MHz */
+#define DEFAULT_MDIO_FREQ	2500000 /* 2.5 MHz */
 #define DEFAULT_HOST_CLOCK	150000000 /* 150 MHz */
 
 /* Wait till MDIO interface is ready to accept a new transaction.*/
@@ -147,15 +147,20 @@ static int axienet_mdio_write(struct mii_bus *bus, int phy_id, int reg,
 /**
  * axienet_mdio_enable - MDIO hardware setup function
  * @lp:		Pointer to axienet local data structure.
+ * @np:		Pointer to mdio device tree node.
  *
- * Return:	0 on success, -ETIMEDOUT on a timeout.
+ * Return:	0 on success, -ETIMEDOUT on a timeout, -EOVERFLOW on a clock
+ *		divisor overflow.
  *
  * Sets up the MDIO interface by initializing the MDIO clock and enabling the
  * MDIO interface in hardware.
  **/
-int axienet_mdio_enable(struct axienet_local *lp)
+static int axienet_mdio_enable(struct axienet_local *lp, struct device_node *np)
 {
+	u32 mdio_freq = DEFAULT_MDIO_FREQ;
 	u32 host_clock;
+	u32 clk_div;
+	int ret;
 
 	lp->mii_clk_div = 0;
 
@@ -184,6 +189,12 @@ int axienet_mdio_enable(struct axienet_local *lp)
 			    host_clock);
 	}
 
+	if (np)
+		of_property_read_u32(np, "clock-frequency", &mdio_freq);
+	if (mdio_freq != DEFAULT_MDIO_FREQ)
+		netdev_info(lp->ndev, "Setting non-standard mdio bus frequency to %u Hz\n",
+			    mdio_freq);
+
 	/* clk_div can be calculated by deriving it from the equation:
 	 * fMDIO = fHOST / ((1 + clk_div) * 2)
 	 *
@@ -209,40 +220,42 @@ int axienet_mdio_enable(struct axienet_local *lp)
 	 * "clock-frequency" from the CPU
 	 */
 
-	lp->mii_clk_div = (host_clock / (MAX_MDIO_FREQ * 2)) - 1;
+	clk_div = (host_clock / (mdio_freq * 2)) - 1;
 	/* If there is any remainder from the division of
-	 * fHOST / (MAX_MDIO_FREQ * 2), then we need to add
-	 * 1 to the clock divisor or we will surely be above 2.5 MHz
+	 * fHOST / (mdio_freq * 2), then we need to add
+	 * 1 to the clock divisor or we will surely be
+	 * above the requested frequency
 	 */
-	if (host_clock % (MAX_MDIO_FREQ * 2))
-		lp->mii_clk_div++;
+	if (host_clock % (mdio_freq * 2))
+		clk_div++;
+
+	/* Check for overflow of mii_clk_div */
+	if (clk_div & ~XAE_MDIO_MC_CLOCK_DIVIDE_MAX) {
+		netdev_warn(lp->ndev, "MDIO clock divisor overflow\n");
+		return -EOVERFLOW;
+	}
+	lp->mii_clk_div = (u8)clk_div;
 
 	netdev_dbg(lp->ndev,
 		   "Setting MDIO clock divisor to %u/%u Hz host clock.\n",
 		   lp->mii_clk_div, host_clock);
 
-	axienet_iow(lp, XAE_MDIO_MC_OFFSET, lp->mii_clk_div | XAE_MDIO_MC_MDIOEN_MASK);
+	axienet_mdio_mdc_enable(lp);
 
-	return axienet_mdio_wait_until_ready(lp);
-}
+	ret = axienet_mdio_wait_until_ready(lp);
+	if (ret)
+		axienet_mdio_mdc_disable(lp);
 
-/**
- * axienet_mdio_disable - MDIO hardware disable function
- * @lp:		Pointer to axienet local data structure.
- *
- * Disable the MDIO interface in hardware.
- **/
-void axienet_mdio_disable(struct axienet_local *lp)
-{
-	axienet_iow(lp, XAE_MDIO_MC_OFFSET, 0);
+	return ret;
 }
 
 /**
  * axienet_mdio_setup - MDIO setup function
  * @lp:		Pointer to axienet local data structure.
  *
- * Return:	0 on success, -ETIMEDOUT on a timeout, -ENOMEM when
- *		mdiobus_alloc (to allocate memory for mii bus structure) fails.
+ * Return:	0 on success, -ETIMEDOUT on a timeout, -EOVERFLOW on a clock
+ *		divisor overflow, -ENOMEM when mdiobus_alloc (to allocate
+ *		memory for mii bus structure) fails.
  *
  * Sets up the MDIO interface by initializing the MDIO clock.
  * Register the MDIO interface.
@@ -253,10 +266,6 @@ int axienet_mdio_setup(struct axienet_local *lp)
 	struct mii_bus *bus;
 	int ret;
 
-	ret = axienet_mdio_enable(lp);
-	if (ret < 0)
-		return ret;
-
 	bus = mdiobus_alloc();
 	if (!bus)
 		return -ENOMEM;
@@ -272,15 +281,23 @@ int axienet_mdio_setup(struct axienet_local *lp)
 	lp->mii_bus = bus;
 
 	mdio_node = of_get_child_by_name(lp->dev->of_node, "mdio");
+	ret = axienet_mdio_enable(lp, mdio_node);
+	if (ret < 0)
+		goto unregister;
 	ret = of_mdiobus_register(bus, mdio_node);
+	if (ret)
+		goto unregister_mdio_enabled;
 	of_node_put(mdio_node);
-	if (ret) {
-		mdiobus_free(bus);
-		lp->mii_bus = NULL;
-		return ret;
-	}
 	axienet_mdio_mdc_disable(lp);
 	return 0;
+
+unregister_mdio_enabled:
+	axienet_mdio_mdc_disable(lp);
+unregister:
+	of_node_put(mdio_node);
+	mdiobus_free(bus);
+	lp->mii_bus = NULL;
+	return ret;
 }
 
 /**