[PATCH v4 net-next 0/3] net: axienet: Use a DT property to configure frequency of the MDIO bus

[PATCH v4 net-next 0/3] net: axienet: Use a DT property to configure frequency of the MDIO bus

[Andy Chiu]

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 253761a0e61b7.

Changelog:
--- 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.

Andy Chiu (3):
  net: axienet: Unexport and remove unused mdio functions
  net: axienet: set mdio clock according to bus-frequency
  dt-bindings: describe the support of "clock-frequency" in mdio

 .../bindings/net/xilinx_axienet.txt           |  2 +
 drivers/net/ethernet/xilinx/xilinx_axienet.h  |  2 -
 .../net/ethernet/xilinx/xilinx_axienet_mdio.c | 59 +++++++++++--------
 3 files changed, 35 insertions(+), 28 deletions(-)

-- 
2.36.0

[PATCH v4 net-next 1/3] net: axienet: Unexport and remove unused mdio functions

[Andy Chiu]

Both axienet_mdio_enable functions are no longer used in
xilinx_axienet_main.c due to 253761a0e61b7. And axienet_mdio_disable is
not even used in the mdio.c. So unexport and remove them.

Signed-off-by: Andy Chiu <andy.chiu@sifive.com>
Reviewed-by: Greentime Hu <greentime.hu@sifive.com>
Reviewed-by: Andrew Lunn <andrew@lunn.ch>
---
 drivers/net/ethernet/xilinx/xilinx_axienet.h      |  2 --
 drivers/net/ethernet/xilinx/xilinx_axienet_mdio.c | 13 +------------
 2 files changed, 1 insertion(+), 14 deletions(-)

diff --git a/drivers/net/ethernet/xilinx/xilinx_axienet.h b/drivers/net/ethernet/xilinx/xilinx_axienet.h
index 6370c447ac5c..575ff9de8985 100644
--- a/drivers/net/ethernet/xilinx/xilinx_axienet.h
+++ b/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);
 
diff --git a/drivers/net/ethernet/xilinx/xilinx_axienet_mdio.c b/drivers/net/ethernet/xilinx/xilinx_axienet_mdio.c
index 0b3b6935c558..e1f51a071888 100644
--- a/drivers/net/ethernet/xilinx/xilinx_axienet_mdio.c
+++ b/drivers/net/ethernet/xilinx/xilinx_axienet_mdio.c
@@ -153,7 +153,7 @@ static int axienet_mdio_write(struct mii_bus *bus, int phy_id, int reg,
  * 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)
 {
 	u32 host_clock;
 
@@ -226,17 +226,6 @@ int axienet_mdio_enable(struct axienet_local *lp)
 	return axienet_mdio_wait_until_ready(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);
-}
-
 /**
  * axienet_mdio_setup - MDIO setup function
  * @lp:		Pointer to axienet local data structure.
-- 
2.36.0

[PATCH v4 net-next 2/3] net: axienet: set mdio clock according to bus-frequency

[Andy Chiu]

Some FPGA platforms have 80KHz MDIO bus frequency constraint when
connecting Ethernet to its on-board external Marvell PHY. Thus, we may
have to set MDIO clock according to the DT. Otherwise, use the default
2.5 MHz, as specified by 802.3, if the entry is not present.

Also, change MAX_MDIO_FREQ to DEFAULT_MDIO_FREQ because we may actually
set MDIO bus frequency higher than 2.5MHz if undelying devices support
it.

Signed-off-by: Andy Chiu <andy.chiu@sifive.com>
Reviewed-by: Greentime Hu <greentime.hu@sifive.com>
Reviewed-by: Andrew Lunn <andrew@lunn.ch>
---
 .../net/ethernet/xilinx/xilinx_axienet_mdio.c | 48 +++++++++++++------
 1 file changed, 33 insertions(+), 15 deletions(-)

diff --git a/drivers/net/ethernet/xilinx/xilinx_axienet_mdio.c b/drivers/net/ethernet/xilinx/xilinx_axienet_mdio.c
index e1f51a071888..789a90997f4b 100644
--- a/drivers/net/ethernet/xilinx/xilinx_axienet_mdio.c
+++ b/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 +147,18 @@ 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.
  *
  * Sets up the MDIO interface by initializing the MDIO clock and enabling the
  * MDIO interface in hardware.
  **/
-static 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;
 
 	lp->mii_clk_div = 0;
 
@@ -184,6 +187,12 @@ static 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)
 	 *
@@ -209,13 +218,20 @@ static 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
+	 * fHOST / (mdio_freq * 2), then we need to add
 	 * 1 to the clock divisor or we will surely be above 2.5 MHz
 	 */
-	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",
@@ -242,10 +258,6 @@ 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;
@@ -261,15 +273,21 @@ 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;
 	of_node_put(mdio_node);
-	if (ret) {
-		mdiobus_free(bus);
-		lp->mii_bus = NULL;
-		return ret;
-	}
 	axienet_mdio_mdc_disable(lp);
 	return 0;
+
+unregister:
+	of_node_put(mdio_node);
+	mdiobus_free(bus);
+	lp->mii_bus = NULL;
+	return ret;
 }
 
 /**
-- 
2.36.0

[PATCH v4 net-next 3/3] dt-bindings: describe the support of "clock-frequency" in mdio

[Andy Chiu]

mdio bus frequency can be configured at boottime by a property in DT
now, so add a description to it.

Signed-off-by: Andy Chiu <andy.chiu@sifive.com>
Reviewed-by: Greentime Hu <greentime.hu@sifive.com>
Reviewed-by: Andrew Lunn <andrew@lunn.ch>
Acked-by: Rob Herring <robh@kernel.org>
---
 Documentation/devicetree/bindings/net/xilinx_axienet.txt | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/Documentation/devicetree/bindings/net/xilinx_axienet.txt b/Documentation/devicetree/bindings/net/xilinx_axienet.txt
index 1aa4c6006cd0..80e505a2fda1 100644
--- a/Documentation/devicetree/bindings/net/xilinx_axienet.txt
+++ b/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
-- 
2.36.0

RE: [PATCH v4 net-next 2/3] net: axienet: set mdio clock according to bus-frequency

[Pandey, Radhey Shyam]

> -----Original Message-----
> From: Andy Chiu <andy.chiu@sifive.com>
> Sent: Thursday, November 17, 2022 9:18 AM
> To: davem@davemloft.net; andrew@lunn.ch; kuba@kernel.org;
> michal.simek@xilinx.com; radhey.shyam.pandey@xilinx.com
> Cc: netdev@vger.kernel.org; devicetree@vger.kernel.org; linux-arm-
> kernel@lists.infradead.org; robh+dt@kernel.org; pabeni@redhat.com;
> edumazet@google.com; andy.chiu@sifive.com; greentime.hu@sifive.com
> Subject: [PATCH v4 net-next 2/3] net: axienet: set mdio clock according to
> bus-frequency
> 
> CAUTION: This message has originated from an External Source. Please use
> proper judgment and caution when opening attachments, clicking links, or
> responding to this email.
> 
> 
> Some FPGA platforms have 80KHz MDIO bus frequency constraint when
> connecting Ethernet to its on-board external Marvell PHY. Thus, we may have
> to set MDIO clock according to the DT. Otherwise, use the default
> 2.5 MHz, as specified by 802.3, if the entry is not present.
> 
> Also, change MAX_MDIO_FREQ to DEFAULT_MDIO_FREQ because we may
> actually set MDIO bus frequency higher than 2.5MHz if undelying devices
> support it.
> 
> Signed-off-by: Andy Chiu <andy.chiu@sifive.com>
> Reviewed-by: Greentime Hu <greentime.hu@sifive.com>
> Reviewed-by: Andrew Lunn <andrew@lunn.ch>
> ---
>  .../net/ethernet/xilinx/xilinx_axienet_mdio.c | 48 +++++++++++++------
>  1 file changed, 33 insertions(+), 15 deletions(-)
> 
> diff --git a/drivers/net/ethernet/xilinx/xilinx_axienet_mdio.c
> b/drivers/net/ethernet/xilinx/xilinx_axienet_mdio.c
> index e1f51a071888..789a90997f4b 100644
> --- a/drivers/net/ethernet/xilinx/xilinx_axienet_mdio.c
> +++ b/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 +147,18 @@ 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.

We are now also returning -EOVERFLOW. Please update the description.

>   *
>   * Sets up the MDIO interface by initializing the MDIO clock and enabling the
>   * MDIO interface in hardware.
>   **/
> -static 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;
> 
>         lp->mii_clk_div = 0;
> 
> @@ -184,6 +187,12 @@ static int axienet_mdio_enable(struct axienet_local
> *lp)
>                             host_clock);
>         }
> 
Binding 3/3 patch should be before this patch. 

> +       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)
>          *
> @@ -209,13 +218,20 @@ static 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
> +        * fHOST / (mdio_freq * 2), then we need to add
>          * 1 to the clock divisor or we will surely be above 2.5 MHz
>          */
> -       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", @@ -
> 242,10 +258,6 @@ 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;
> @@ -261,15 +273,21 @@ 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;

Missing axienet_mdio_mdc_disable in error path. 

Also return documentation of axienet_mdio_setup needs a update.

>         of_node_put(mdio_node);
> -       if (ret) {
> -               mdiobus_free(bus);
> -               lp->mii_bus = NULL;
> -               return ret;
> -       }
>         axienet_mdio_mdc_disable(lp);
>         return 0;
> +
> +unregister:
> +       of_node_put(mdio_node);
> +       mdiobus_free(bus);
> +       lp->mii_bus = NULL;
> +       return ret;
>  }
> 
>  /**
> --
> 2.36.0