[PATCH v3 0/3] Add reset deassertion for Aspeed MDIO

[PATCH v3 0/3] Add reset deassertion for Aspeed MDIO

[Dylan Hung]

Add missing reset deassertion for Aspeed MDIO bus controller. The reset
is asserted by the hardware when power-on so the driver only needs to
deassert it. To be able to work with the old DT blobs, the reset is
optional since it may be deasserted by the bootloader or the previous
kernel.

V3:
- remove reset property from the required list of the device tree
  bindings
- remove "Cc: stable@vger.kernel.org" from the commit messages
- add more description in the commit message of the dt-binding

V2:
- add reset property in the device tree bindings
- add reset assertion in the error path and driver remove

Dylan Hung (3):
  dt-bindings: net: add reset property for aspeed, ast2600-mdio binding
  net: mdio: add reset control for Aspeed MDIO
  ARM: dts: aspeed: add reset properties into MDIO nodes

 .../bindings/net/aspeed,ast2600-mdio.yaml         |  5 +++++
 arch/arm/boot/dts/aspeed-g6.dtsi                  |  4 ++++
 drivers/net/mdio/mdio-aspeed.c                    | 15 ++++++++++++++-
 3 files changed, 23 insertions(+), 1 deletion(-)

-- 
2.25.1

[PATCH RESEND v3 1/3] dt-bindings: net: add reset property for aspeed, ast2600-mdio binding

[Dylan Hung]

The AST2600 MDIO bus controller has a reset control bit and must be
deasserted before manipulating the MDIO controller. By default, the
hardware asserts the reset so the driver only need to deassert it.

Regarding to the old DT blobs which don't have reset property in them,
the reset deassertion is usually done by the bootloader so the reset
property is optional to work with them.

Signed-off-by: Dylan Hung <dylan_hung@aspeedtech.com>
Reviewed-by: Krzysztof Kozlowski <krzk@kernel.org>
---
 .../devicetree/bindings/net/aspeed,ast2600-mdio.yaml         | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/Documentation/devicetree/bindings/net/aspeed,ast2600-mdio.yaml b/Documentation/devicetree/bindings/net/aspeed,ast2600-mdio.yaml
index 1c88820cbcdf..7f43b4fe86a3 100644
--- a/Documentation/devicetree/bindings/net/aspeed,ast2600-mdio.yaml
+++ b/Documentation/devicetree/bindings/net/aspeed,ast2600-mdio.yaml
@@ -20,10 +20,14 @@ allOf:
 properties:
   compatible:
     const: aspeed,ast2600-mdio
+
   reg:
     maxItems: 1
     description: The register range of the MDIO controller instance
 
+  resets:
+    maxItems: 1
+
 required:
   - compatible
   - reg
@@ -39,6 +43,7 @@ examples:
             reg = <0x1e650000 0x8>;
             #address-cells = <1>;
             #size-cells = <0>;
+            resets = <&syscon 35>;
 
             ethphy0: ethernet-phy@0 {
                     compatible = "ethernet-phy-ieee802.3-c22";
-- 
2.25.1

[PATCH RESEND v3 2/3] net: mdio: add reset control for Aspeed MDIO

[Dylan Hung]

Add reset assertion/deassertion for Aspeed MDIO.  There are 4 MDIO
controllers embedded in Aspeed AST2600 SOC and share one reset control
register SCU50[3].  To work with old DT blobs which don't have the reset
property, devm_reset_control_get_optional_shared is used in this change.

Signed-off-by: Dylan Hung <dylan_hung@aspeedtech.com>
Reviewed-by: Philipp Zabel <p.zabel@pengutronix.de>
---
 drivers/net/mdio/mdio-aspeed.c | 15 ++++++++++++++-
 1 file changed, 14 insertions(+), 1 deletion(-)

diff --git a/drivers/net/mdio/mdio-aspeed.c b/drivers/net/mdio/mdio-aspeed.c
index e2273588c75b..1afb58ccc524 100644
--- a/drivers/net/mdio/mdio-aspeed.c
+++ b/drivers/net/mdio/mdio-aspeed.c
@@ -3,6 +3,7 @@
 
 #include <linux/bitfield.h>
 #include <linux/delay.h>
+#include <linux/reset.h>
 #include <linux/iopoll.h>
 #include <linux/mdio.h>
 #include <linux/module.h>
@@ -37,6 +38,7 @@
 
 struct aspeed_mdio {
 	void __iomem *base;
+	struct reset_control *reset;
 };
 
 static int aspeed_mdio_read(struct mii_bus *bus, int addr, int regnum)
@@ -120,6 +122,12 @@ static int aspeed_mdio_probe(struct platform_device *pdev)
 	if (IS_ERR(ctx->base))
 		return PTR_ERR(ctx->base);
 
+	ctx->reset = devm_reset_control_get_optional_shared(&pdev->dev, NULL);
+	if (IS_ERR(ctx->reset))
+		return PTR_ERR(ctx->reset);
+
+	reset_control_deassert(ctx->reset);
+
 	bus->name = DRV_NAME;
 	snprintf(bus->id, MII_BUS_ID_SIZE, "%s%d", pdev->name, pdev->id);
 	bus->parent = &pdev->dev;
@@ -129,6 +137,7 @@ static int aspeed_mdio_probe(struct platform_device *pdev)
 	rc = of_mdiobus_register(bus, pdev->dev.of_node);
 	if (rc) {
 		dev_err(&pdev->dev, "Cannot register MDIO bus!\n");
+		reset_control_assert(ctx->reset);
 		return rc;
 	}
 
@@ -139,7 +148,11 @@ static int aspeed_mdio_probe(struct platform_device *pdev)
 
 static int aspeed_mdio_remove(struct platform_device *pdev)
 {
-	mdiobus_unregister(platform_get_drvdata(pdev));
+	struct mii_bus *bus = (struct mii_bus *)platform_get_drvdata(pdev);
+	struct aspeed_mdio *ctx = bus->priv;
+
+	reset_control_assert(ctx->reset);
+	mdiobus_unregister(bus);
 
 	return 0;
 }
-- 
2.25.1

[PATCH RESEND v3 3/3] ARM: dts: aspeed: add reset properties into MDIO nodes

[Dylan Hung]

Add reset control properties into MDIO nodes.  The 4 MDIO controllers in
AST2600 SOC share one reset control bit SCU50[3].

Signed-off-by: Dylan Hung <dylan_hung@aspeedtech.com>
---
 arch/arm/boot/dts/aspeed-g6.dtsi | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/arch/arm/boot/dts/aspeed-g6.dtsi b/arch/arm/boot/dts/aspeed-g6.dtsi
index c32e87fad4dc..ab20ea8d829d 100644
--- a/arch/arm/boot/dts/aspeed-g6.dtsi
+++ b/arch/arm/boot/dts/aspeed-g6.dtsi
@@ -181,6 +181,7 @@ mdio0: mdio@1e650000 {
 			status = "disabled";
 			pinctrl-names = "default";
 			pinctrl-0 = <&pinctrl_mdio1_default>;
+			resets = <&syscon ASPEED_RESET_MII>;
 		};
 
 		mdio1: mdio@1e650008 {
@@ -191,6 +192,7 @@ mdio1: mdio@1e650008 {
 			status = "disabled";
 			pinctrl-names = "default";
 			pinctrl-0 = <&pinctrl_mdio2_default>;
+			resets = <&syscon ASPEED_RESET_MII>;
 		};
 
 		mdio2: mdio@1e650010 {
@@ -201,6 +203,7 @@ mdio2: mdio@1e650010 {
 			status = "disabled";
 			pinctrl-names = "default";
 			pinctrl-0 = <&pinctrl_mdio3_default>;
+			resets = <&syscon ASPEED_RESET_MII>;
 		};
 
 		mdio3: mdio@1e650018 {
@@ -211,6 +214,7 @@ mdio3: mdio@1e650018 {
 			status = "disabled";
 			pinctrl-names = "default";
 			pinctrl-0 = <&pinctrl_mdio4_default>;
+			resets = <&syscon ASPEED_RESET_MII>;
 		};
 
 		mac0: ftgmac@1e660000 {
-- 
2.25.1

Re: [PATCH RESEND v3 1/3] dt-bindings: net: add reset property for aspeed, ast2600-mdio binding

[Andrew Jeffery]

Hi Dylan,

On Thu, 7 Apr 2022, at 17:27, Dylan Hung wrote:
> The AST2600 MDIO bus controller has a reset control bit and must be
> deasserted before manipulating the MDIO controller. By default, the
> hardware asserts the reset so the driver only need to deassert it.
>
> Regarding to the old DT blobs which don't have reset property in them,
> the reset deassertion is usually done by the bootloader so the reset
> property is optional to work with them.
>
> Signed-off-by: Dylan Hung <dylan_hung@aspeedtech.com>
> Reviewed-by: Krzysztof Kozlowski <krzk@kernel.org>
> ---
>  .../devicetree/bindings/net/aspeed,ast2600-mdio.yaml         | 5 +++++
>  1 file changed, 5 insertions(+)
>
> diff --git 
> a/Documentation/devicetree/bindings/net/aspeed,ast2600-mdio.yaml 
> b/Documentation/devicetree/bindings/net/aspeed,ast2600-mdio.yaml
> index 1c88820cbcdf..7f43b4fe86a3 100644
> --- a/Documentation/devicetree/bindings/net/aspeed,ast2600-mdio.yaml
> +++ b/Documentation/devicetree/bindings/net/aspeed,ast2600-mdio.yaml
> @@ -20,10 +20,14 @@ allOf:
>  properties:
>    compatible:
>      const: aspeed,ast2600-mdio
> +
>    reg:
>      maxItems: 1
>      description: The register range of the MDIO controller instance
> 
> +  resets:
> +    maxItems: 1
> +
>  required:
>    - compatible
>    - reg
> @@ -39,6 +43,7 @@ examples:
>              reg = <0x1e650000 0x8>;
>              #address-cells = <1>;
>              #size-cells = <0>;
> +            resets = <&syscon 35>;

This is just the example but we should probably have it do the 
canonical thing and use ASPEED_RESET_MII from 
include/dt-bindings/clock/ast2600-clock.h

Andrew

Re: [PATCH RESEND v3 2/3] net: mdio: add reset control for Aspeed MDIO

[Andrew Jeffery]

On Thu, 7 Apr 2022, at 17:27, Dylan Hung wrote:
> Add reset assertion/deassertion for Aspeed MDIO.  There are 4 MDIO
> controllers embedded in Aspeed AST2600 SOC and share one reset control
> register SCU50[3].  To work with old DT blobs which don't have the reset
> property, devm_reset_control_get_optional_shared is used in this change.
>
> Signed-off-by: Dylan Hung <dylan_hung@aspeedtech.com>
> Reviewed-by: Philipp Zabel <p.zabel@pengutronix.de>
> ---
>  drivers/net/mdio/mdio-aspeed.c | 15 ++++++++++++++-
>  1 file changed, 14 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/net/mdio/mdio-aspeed.c b/drivers/net/mdio/mdio-aspeed.c
> index e2273588c75b..1afb58ccc524 100644
> --- a/drivers/net/mdio/mdio-aspeed.c
> +++ b/drivers/net/mdio/mdio-aspeed.c
> @@ -3,6 +3,7 @@
> 
>  #include <linux/bitfield.h>
>  #include <linux/delay.h>
> +#include <linux/reset.h>
>  #include <linux/iopoll.h>
>  #include <linux/mdio.h>
>  #include <linux/module.h>
> @@ -37,6 +38,7 @@
> 
>  struct aspeed_mdio {
>  	void __iomem *base;
> +	struct reset_control *reset;
>  };
> 
>  static int aspeed_mdio_read(struct mii_bus *bus, int addr, int regnum)
> @@ -120,6 +122,12 @@ static int aspeed_mdio_probe(struct platform_device *pdev)
>  	if (IS_ERR(ctx->base))
>  		return PTR_ERR(ctx->base);
> 
> +	ctx->reset = devm_reset_control_get_optional_shared(&pdev->dev, NULL);
> +	if (IS_ERR(ctx->reset))
> +		return PTR_ERR(ctx->reset);
> +
> +	reset_control_deassert(ctx->reset);
> +
>  	bus->name = DRV_NAME;
>  	snprintf(bus->id, MII_BUS_ID_SIZE, "%s%d", pdev->name, pdev->id);
>  	bus->parent = &pdev->dev;
> @@ -129,6 +137,7 @@ static int aspeed_mdio_probe(struct platform_device *pdev)
>  	rc = of_mdiobus_register(bus, pdev->dev.of_node);
>  	if (rc) {
>  		dev_err(&pdev->dev, "Cannot register MDIO bus!\n");
> +		reset_control_assert(ctx->reset);
>  		return rc;
>  	}
> 
> @@ -139,7 +148,11 @@ static int aspeed_mdio_probe(struct platform_device *pdev)
> 
>  static int aspeed_mdio_remove(struct platform_device *pdev)
>  {
> -	mdiobus_unregister(platform_get_drvdata(pdev));
> +	struct mii_bus *bus = (struct mii_bus *)platform_get_drvdata(pdev);
> +	struct aspeed_mdio *ctx = bus->priv;
> +
> +	reset_control_assert(ctx->reset);

Isn't this unnecessary because you've used the devm_ variant to acquire 
the reset?

Andrew

Re: [PATCH RESEND v3 3/3] ARM: dts: aspeed: add reset properties into MDIO nodes

[Andrew Jeffery]

On Thu, 7 Apr 2022, at 17:27, Dylan Hung wrote:
> Add reset control properties into MDIO nodes.  The 4 MDIO controllers in
> AST2600 SOC share one reset control bit SCU50[3].
>
> Signed-off-by: Dylan Hung <dylan_hung@aspeedtech.com>

Reviewed-by: Andrew Jeffery <andrew@aj.id.au>

Re: [PATCH RESEND v3 2/3] net: mdio: add reset control for Aspeed MDIO

[Philipp Zabel]

On Mo, 2022-04-11 at 09:50 +0930, Andrew Jeffery wrote:
> 
> On Thu, 7 Apr 2022, at 17:27, Dylan Hung wrote:
> > Add reset assertion/deassertion for Aspeed MDIO.  There are 4 MDIO
> > controllers embedded in Aspeed AST2600 SOC and share one reset control
> > register SCU50[3].  To work with old DT blobs which don't have the reset
> > property, devm_reset_control_get_optional_shared is used in this change.
> > 
> > Signed-off-by: Dylan Hung <dylan_hung@aspeedtech.com>
> > Reviewed-by: Philipp Zabel <p.zabel@pengutronix.de>
> > ---
> >  drivers/net/mdio/mdio-aspeed.c | 15 ++++++++++++++-
> >  1 file changed, 14 insertions(+), 1 deletion(-)
> > 
> > diff --git a/drivers/net/mdio/mdio-aspeed.c b/drivers/net/mdio/mdio-aspeed.c
> > index e2273588c75b..1afb58ccc524 100644
> > --- a/drivers/net/mdio/mdio-aspeed.c
> > +++ b/drivers/net/mdio/mdio-aspeed.c
> > @@ -3,6 +3,7 @@
> > 
> >  #include <linux/bitfield.h>
> >  #include <linux/delay.h>
> > +#include <linux/reset.h>
> >  #include <linux/iopoll.h>
> >  #include <linux/mdio.h>
> >  #include <linux/module.h>
> > @@ -37,6 +38,7 @@
> > 
> >  struct aspeed_mdio {
> >  	void __iomem *base;
> > +	struct reset_control *reset;
> >  };
> > 
> >  static int aspeed_mdio_read(struct mii_bus *bus, int addr, int regnum)
> > @@ -120,6 +122,12 @@ static int aspeed_mdio_probe(struct platform_device *pdev)
> >  	if (IS_ERR(ctx->base))
> >  		return PTR_ERR(ctx->base);
> > 
> > +	ctx->reset = devm_reset_control_get_optional_shared(&pdev->dev, NULL);
> > +	if (IS_ERR(ctx->reset))
> > +		return PTR_ERR(ctx->reset);
> > +
> > +	reset_control_deassert(ctx->reset);
> > +
> >  	bus->name = DRV_NAME;
> >  	snprintf(bus->id, MII_BUS_ID_SIZE, "%s%d", pdev->name, pdev->id);
> >  	bus->parent = &pdev->dev;
> > @@ -129,6 +137,7 @@ static int aspeed_mdio_probe(struct platform_device *pdev)
> >  	rc = of_mdiobus_register(bus, pdev->dev.of_node);
> >  	if (rc) {
> >  		dev_err(&pdev->dev, "Cannot register MDIO bus!\n");
> > +		reset_control_assert(ctx->reset);
> >  		return rc;
> >  	}
> > 
> > @@ -139,7 +148,11 @@ static int aspeed_mdio_probe(struct platform_device *pdev)
> > 
> >  static int aspeed_mdio_remove(struct platform_device *pdev)
> >  {
> > -	mdiobus_unregister(platform_get_drvdata(pdev));
> > +	struct mii_bus *bus = (struct mii_bus *)platform_get_drvdata(pdev);
> > +	struct aspeed_mdio *ctx = bus->priv;
> > +
> > +	reset_control_assert(ctx->reset);
> 
> Isn't this unnecessary because you've used the devm_ variant to acquire 
> the reset?

No, this is correct. deassert/assert needs to be balanced, and the
reset_control_deassert() call in aspeed_mdio_probe() is not devres
managed.

regards
Philipp