[PATCH v5 0/4] PCI: mvebu: Slot support

[PATCH v5 0/4] PCI: mvebu: Slot support

[Pali Rohár]

This patch series add slot support to pci-mvebu.c driver.

Changes in v5:
* Fix compile error due to wrong patch rebasing

Changes in v4:
* Set 239 W when DT slot-power-limit-milliwatt is between 239 W and 250 W
* Fix returning power limit value

Changes in v3:
* Set 600 W when DT slot-power-limit-milliwatt > 600 W

Changes in v2:
* Dropped patch with PCI_EXP_SLTCAP_*_SHIFT macros as it is not needed anymore
* Dropped patch "ARM: dts: turris-omnia: Set PCIe slot-power-limit-milliwatt properties" which was applied
* Added support for PCIe 6.0 slot power limit encodings
* Round down slot power limit value
* Fix handling of slot power limit with scale x1.0 (0x00 value)
* Use FIELD_PREP instead of _SHIFT macros
* Changed commit message to Bjorn's suggestion
* Changed comments in the code to match PCIe spec
* Preserve user settings of PCI_EXP_SLTCTL_ASPL_DISABLE bit

Pali Rohár (4):
  PCI: Add PCI_EXP_SLTCTL_ASPL_DISABLE macro
  dt-bindings: Add 'slot-power-limit-milliwatt' PCIe port property
  PCI: Add function for parsing 'slot-power-limit-milliwatt' DT property
  PCI: mvebu: Add support for sending Set_Slot_Power_Limit message

 Documentation/devicetree/bindings/pci/pci.txt |  6 ++
 drivers/pci/controller/pci-mvebu.c            | 97 ++++++++++++++++++-
 drivers/pci/of.c                              | 70 +++++++++++++
 drivers/pci/pci.h                             | 15 +++
 include/uapi/linux/pci_regs.h                 |  1 +
 5 files changed, 184 insertions(+), 5 deletions(-)

-- 
2.20.1

[PATCH v5 1/4] PCI: Add PCI_EXP_SLTCTL_ASPL_DISABLE macro

[Pali Rohár]

Add macro defining Auto Slot Power Limit Disable bit in Slot Control
Register.

Signed-off-by: Pali Rohár <pali@kernel.org>
Signed-off-by: Marek Behún <kabel@kernel.org>
Acked-by: Bjorn Helgaas <bhelgaas@google.com>
---
 include/uapi/linux/pci_regs.h | 1 +
 1 file changed, 1 insertion(+)

diff --git a/include/uapi/linux/pci_regs.h b/include/uapi/linux/pci_regs.h
index bee1a9ed6e66..108f8523fa04 100644
--- a/include/uapi/linux/pci_regs.h
+++ b/include/uapi/linux/pci_regs.h
@@ -616,6 +616,7 @@
 #define  PCI_EXP_SLTCTL_PWR_OFF        0x0400 /* Power Off */
 #define  PCI_EXP_SLTCTL_EIC	0x0800	/* Electromechanical Interlock Control */
 #define  PCI_EXP_SLTCTL_DLLSCE	0x1000	/* Data Link Layer State Changed Enable */
+#define  PCI_EXP_SLTCTL_ASPL_DISABLE	0x2000 /* Auto Slot Power Limit Disable */
 #define  PCI_EXP_SLTCTL_IBPD_DISABLE	0x4000 /* In-band PD disable */
 #define PCI_EXP_SLTSTA		0x1a	/* Slot Status */
 #define  PCI_EXP_SLTSTA_ABP	0x0001	/* Attention Button Pressed */
-- 
2.20.1

[PATCH v5 2/4] dt-bindings: Add 'slot-power-limit-milliwatt' PCIe port property

[Pali Rohár]

This property specifies slot power limit in mW unit. It is a form-factor
and board specific value and must be initialized by hardware.

Some PCIe controllers delegate this work to software to allow hardware
flexibility and therefore this property basically specifies what should
host bridge program into PCIe Slot Capabilities registers.

The property needs to be specified in mW unit instead of the special format
defined by Slot Capabilities (which encodes scaling factor or different
unit). Host drivers should convert the value from mW to needed format.

Signed-off-by: Pali Rohár <pali@kernel.org>
Signed-off-by: Marek Behún <kabel@kernel.org>

---
This change was already accepted into dt-schema repo by Rob Herring:
https://github.com/devicetree-org/dt-schema/pull/66
---
 Documentation/devicetree/bindings/pci/pci.txt | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/Documentation/devicetree/bindings/pci/pci.txt b/Documentation/devicetree/bindings/pci/pci.txt
index 6a8f2874a24d..b0cc133ed00d 100644
--- a/Documentation/devicetree/bindings/pci/pci.txt
+++ b/Documentation/devicetree/bindings/pci/pci.txt
@@ -32,6 +32,12 @@ driver implementation may support the following properties:
    root port to downstream device and host bridge drivers can do programming
    which depends on CLKREQ signal existence. For example, programming root port
    not to advertise ASPM L1 Sub-States support if there is no CLKREQ signal.
+- slot-power-limit-milliwatt:
+   If present, this property specifies slot power limit in milliwatts. Host
+   drivers can parse this property and use it for programming Root Port or host
+   bridge, or for composing and sending PCIe Set_Slot_Power_Limit messages
+   through the Root Port or host bridge when transitioning PCIe link from a
+   non-DL_Up Status to a DL_Up Status.
 
 PCI-PCI Bridge properties
 -------------------------
-- 
2.20.1

[PATCH v5 3/4] PCI: Add function for parsing 'slot-power-limit-milliwatt' DT property

[Pali Rohár]

Add function of_pci_get_slot_power_limit(), which parses the
'slot-power-limit-milliwatt' DT property, returning the value in
milliwatts and in format ready for the PCIe Slot Capabilities Register.

Signed-off-by: Pali Rohár <pali@kernel.org>
Signed-off-by: Marek Behún <kabel@kernel.org>
Reviewed-by: Rob Herring <robh@kernel.org>
---
Changes in v4:
* Set 239 W when DT slot-power-limit-milliwatt is between 239 W and 250 W
* Fix returning power limit value
Changes in v3:
* Set 600 W when DT slot-power-limit-milliwatt > 600 W
Changes in v2:
* Added support for PCIe 6.0 slot power limit encodings
* Round down slot power limit value
---
 drivers/pci/of.c  | 70 +++++++++++++++++++++++++++++++++++++++++++++++
 drivers/pci/pci.h | 15 ++++++++++
 2 files changed, 85 insertions(+)

diff --git a/drivers/pci/of.c b/drivers/pci/of.c
index cb2e8351c2cc..6c1b81304665 100644
--- a/drivers/pci/of.c
+++ b/drivers/pci/of.c
@@ -633,3 +633,73 @@ int of_pci_get_max_link_speed(struct device_node *node)
 	return max_link_speed;
 }
 EXPORT_SYMBOL_GPL(of_pci_get_max_link_speed);
+
+/**
+ * of_pci_get_slot_power_limit - Parses the "slot-power-limit-milliwatt"
+ *				 property.
+ *
+ * @node: device tree node with the slot power limit information
+ * @slot_power_limit_value: pointer where the value should be stored in PCIe
+ *			    Slot Capabilities Register format
+ * @slot_power_limit_scale: pointer where the scale should be stored in PCIe
+ *			    Slot Capabilities Register format
+ *
+ * Returns the slot power limit in milliwatts and if @slot_power_limit_value
+ * and @slot_power_limit_scale pointers are non-NULL, fills in the value and
+ * scale in format used by PCIe Slot Capabilities Register.
+ *
+ * If the property is not found or is invalid, returns 0.
+ */
+u32 of_pci_get_slot_power_limit(struct device_node *node,
+				u8 *slot_power_limit_value,
+				u8 *slot_power_limit_scale)
+{
+	u32 slot_power_limit_mw;
+	u8 value, scale;
+
+	if (of_property_read_u32(node, "slot-power-limit-milliwatt",
+				 &slot_power_limit_mw))
+		slot_power_limit_mw = 0;
+
+	/* Calculate Slot Power Limit Value and Slot Power Limit Scale */
+	if (slot_power_limit_mw == 0) {
+		value = 0x00;
+		scale = 0;
+	} else if (slot_power_limit_mw <= 255) {
+		value = slot_power_limit_mw;
+		scale = 3;
+	} else if (slot_power_limit_mw <= 255*10) {
+		value = slot_power_limit_mw / 10;
+		scale = 2;
+		slot_power_limit_mw = slot_power_limit_mw / 10 * 10;
+	} else if (slot_power_limit_mw <= 255*100) {
+		value = slot_power_limit_mw / 100;
+		scale = 1;
+		slot_power_limit_mw = slot_power_limit_mw / 100 * 100;
+	} else if (slot_power_limit_mw <= 239*1000) {
+		value = slot_power_limit_mw / 1000;
+		scale = 0;
+		slot_power_limit_mw = slot_power_limit_mw / 1000 * 1000;
+	} else if (slot_power_limit_mw < 250*1000) {
+		value = 0xEF;
+		scale = 0;
+		slot_power_limit_mw = 239*1000;
+	} else if (slot_power_limit_mw <= 600*1000) {
+		value = 0xF0 + (slot_power_limit_mw / 1000 - 250) / 25;
+		scale = 0;
+		slot_power_limit_mw = slot_power_limit_mw / (1000*25) * (1000*25);
+	} else {
+		value = 0xFE;
+		scale = 0;
+		slot_power_limit_mw = 600*1000;
+	}
+
+	if (slot_power_limit_value)
+		*slot_power_limit_value = value;
+
+	if (slot_power_limit_scale)
+		*slot_power_limit_scale = scale;
+
+	return slot_power_limit_mw;
+}
+EXPORT_SYMBOL_GPL(of_pci_get_slot_power_limit);
diff --git a/drivers/pci/pci.h b/drivers/pci/pci.h
index 3d60cabde1a1..e10cdec6c56e 100644
--- a/drivers/pci/pci.h
+++ b/drivers/pci/pci.h
@@ -627,6 +627,9 @@ struct device_node;
 int of_pci_parse_bus_range(struct device_node *node, struct resource *res);
 int of_get_pci_domain_nr(struct device_node *node);
 int of_pci_get_max_link_speed(struct device_node *node);
+u32 of_pci_get_slot_power_limit(struct device_node *node,
+				u8 *slot_power_limit_value,
+				u8 *slot_power_limit_scale);
 void pci_set_of_node(struct pci_dev *dev);
 void pci_release_of_node(struct pci_dev *dev);
 void pci_set_bus_of_node(struct pci_bus *bus);
@@ -653,6 +656,18 @@ of_pci_get_max_link_speed(struct device_node *node)
 	return -EINVAL;
 }
 
+static inline u32
+of_pci_get_slot_power_limit(struct device_node *node,
+			    u8 *slot_power_limit_value,
+			    u8 *slot_power_limit_scale)
+{
+	if (slot_power_limit_value)
+		*slot_power_limit_value = 0;
+	if (slot_power_limit_scale)
+		*slot_power_limit_scale = 0;
+	return 0;
+}
+
 static inline void pci_set_of_node(struct pci_dev *dev) { }
 static inline void pci_release_of_node(struct pci_dev *dev) { }
 static inline void pci_set_bus_of_node(struct pci_bus *bus) { }
-- 
2.20.1

Re: [PATCH v5 3/4] PCI: Add function for parsing 'slot-power-limit-milliwatt' DT property

[Bjorn Helgaas]

On Tue, Apr 12, 2022 at 11:49:45AM +0200, Pali Rohár wrote:
> Add function of_pci_get_slot_power_limit(), which parses the
> 'slot-power-limit-milliwatt' DT property, returning the value in
> milliwatts and in format ready for the PCIe Slot Capabilities Register.
> 
> Signed-off-by: Pali Rohár <pali@kernel.org>
> Signed-off-by: Marek Behún <kabel@kernel.org>
> Reviewed-by: Rob Herring <robh@kernel.org>

Looks good to me!  Thank you!

Reviewed-by: Bjorn Helgaas <bhelgaas@google.com>

> ---
> Changes in v4:
> * Set 239 W when DT slot-power-limit-milliwatt is between 239 W and 250 W
> * Fix returning power limit value
> Changes in v3:
> * Set 600 W when DT slot-power-limit-milliwatt > 600 W
> Changes in v2:
> * Added support for PCIe 6.0 slot power limit encodings
> * Round down slot power limit value
> ---
>  drivers/pci/of.c  | 70 +++++++++++++++++++++++++++++++++++++++++++++++
>  drivers/pci/pci.h | 15 ++++++++++
>  2 files changed, 85 insertions(+)
> 
> diff --git a/drivers/pci/of.c b/drivers/pci/of.c
> index cb2e8351c2cc..6c1b81304665 100644
> --- a/drivers/pci/of.c
> +++ b/drivers/pci/of.c
> @@ -633,3 +633,73 @@ int of_pci_get_max_link_speed(struct device_node *node)
>  	return max_link_speed;
>  }
>  EXPORT_SYMBOL_GPL(of_pci_get_max_link_speed);
> +
> +/**
> + * of_pci_get_slot_power_limit - Parses the "slot-power-limit-milliwatt"
> + *				 property.
> + *
> + * @node: device tree node with the slot power limit information
> + * @slot_power_limit_value: pointer where the value should be stored in PCIe
> + *			    Slot Capabilities Register format
> + * @slot_power_limit_scale: pointer where the scale should be stored in PCIe
> + *			    Slot Capabilities Register format
> + *
> + * Returns the slot power limit in milliwatts and if @slot_power_limit_value
> + * and @slot_power_limit_scale pointers are non-NULL, fills in the value and
> + * scale in format used by PCIe Slot Capabilities Register.
> + *
> + * If the property is not found or is invalid, returns 0.
> + */
> +u32 of_pci_get_slot_power_limit(struct device_node *node,
> +				u8 *slot_power_limit_value,
> +				u8 *slot_power_limit_scale)
> +{
> +	u32 slot_power_limit_mw;
> +	u8 value, scale;
> +
> +	if (of_property_read_u32(node, "slot-power-limit-milliwatt",
> +				 &slot_power_limit_mw))
> +		slot_power_limit_mw = 0;
> +
> +	/* Calculate Slot Power Limit Value and Slot Power Limit Scale */
> +	if (slot_power_limit_mw == 0) {
> +		value = 0x00;
> +		scale = 0;
> +	} else if (slot_power_limit_mw <= 255) {
> +		value = slot_power_limit_mw;
> +		scale = 3;
> +	} else if (slot_power_limit_mw <= 255*10) {
> +		value = slot_power_limit_mw / 10;
> +		scale = 2;
> +		slot_power_limit_mw = slot_power_limit_mw / 10 * 10;
> +	} else if (slot_power_limit_mw <= 255*100) {
> +		value = slot_power_limit_mw / 100;
> +		scale = 1;
> +		slot_power_limit_mw = slot_power_limit_mw / 100 * 100;
> +	} else if (slot_power_limit_mw <= 239*1000) {
> +		value = slot_power_limit_mw / 1000;
> +		scale = 0;
> +		slot_power_limit_mw = slot_power_limit_mw / 1000 * 1000;
> +	} else if (slot_power_limit_mw < 250*1000) {
> +		value = 0xEF;
> +		scale = 0;
> +		slot_power_limit_mw = 239*1000;
> +	} else if (slot_power_limit_mw <= 600*1000) {
> +		value = 0xF0 + (slot_power_limit_mw / 1000 - 250) / 25;
> +		scale = 0;
> +		slot_power_limit_mw = slot_power_limit_mw / (1000*25) * (1000*25);
> +	} else {
> +		value = 0xFE;
> +		scale = 0;
> +		slot_power_limit_mw = 600*1000;
> +	}
> +
> +	if (slot_power_limit_value)
> +		*slot_power_limit_value = value;
> +
> +	if (slot_power_limit_scale)
> +		*slot_power_limit_scale = scale;
> +
> +	return slot_power_limit_mw;
> +}
> +EXPORT_SYMBOL_GPL(of_pci_get_slot_power_limit);
> diff --git a/drivers/pci/pci.h b/drivers/pci/pci.h
> index 3d60cabde1a1..e10cdec6c56e 100644
> --- a/drivers/pci/pci.h
> +++ b/drivers/pci/pci.h
> @@ -627,6 +627,9 @@ struct device_node;
>  int of_pci_parse_bus_range(struct device_node *node, struct resource *res);
>  int of_get_pci_domain_nr(struct device_node *node);
>  int of_pci_get_max_link_speed(struct device_node *node);
> +u32 of_pci_get_slot_power_limit(struct device_node *node,
> +				u8 *slot_power_limit_value,
> +				u8 *slot_power_limit_scale);
>  void pci_set_of_node(struct pci_dev *dev);
>  void pci_release_of_node(struct pci_dev *dev);
>  void pci_set_bus_of_node(struct pci_bus *bus);
> @@ -653,6 +656,18 @@ of_pci_get_max_link_speed(struct device_node *node)
>  	return -EINVAL;
>  }
>  
> +static inline u32
> +of_pci_get_slot_power_limit(struct device_node *node,
> +			    u8 *slot_power_limit_value,
> +			    u8 *slot_power_limit_scale)
> +{
> +	if (slot_power_limit_value)
> +		*slot_power_limit_value = 0;
> +	if (slot_power_limit_scale)
> +		*slot_power_limit_scale = 0;
> +	return 0;
> +}
> +
>  static inline void pci_set_of_node(struct pci_dev *dev) { }
>  static inline void pci_release_of_node(struct pci_dev *dev) { }
>  static inline void pci_set_bus_of_node(struct pci_bus *bus) { }
> -- 
> 2.20.1
> 
> 
> _______________________________________________
> linux-arm-kernel mailing list
> linux-arm-kernel@lists.infradead.org
> http://lists.infradead.org/mailman/listinfo/linux-arm-kernel

Re: [PATCH v5 3/4] PCI: Add function for parsing 'slot-power-limit-milliwatt' DT property

[Pali Rohár]

On Wednesday 13 April 2022 15:24:33 Bjorn Helgaas wrote:
> On Tue, Apr 12, 2022 at 11:49:45AM +0200, Pali Rohár wrote:
> > Add function of_pci_get_slot_power_limit(), which parses the
> > 'slot-power-limit-milliwatt' DT property, returning the value in
> > milliwatts and in format ready for the PCIe Slot Capabilities Register.
> > 
> > Signed-off-by: Pali Rohár <pali@kernel.org>
> > Signed-off-by: Marek Behún <kabel@kernel.org>
> > Reviewed-by: Rob Herring <robh@kernel.org>
> 
> Looks good to me!  Thank you!
> 
> Reviewed-by: Bjorn Helgaas <bhelgaas@google.com>

Perfect!

Lorenzo, is this patch series OK now for merging?

> > ---
> > Changes in v4:
> > * Set 239 W when DT slot-power-limit-milliwatt is between 239 W and 250 W
> > * Fix returning power limit value
> > Changes in v3:
> > * Set 600 W when DT slot-power-limit-milliwatt > 600 W
> > Changes in v2:
> > * Added support for PCIe 6.0 slot power limit encodings
> > * Round down slot power limit value
> > ---
> >  drivers/pci/of.c  | 70 +++++++++++++++++++++++++++++++++++++++++++++++
> >  drivers/pci/pci.h | 15 ++++++++++
> >  2 files changed, 85 insertions(+)
> > 
> > diff --git a/drivers/pci/of.c b/drivers/pci/of.c
> > index cb2e8351c2cc..6c1b81304665 100644
> > --- a/drivers/pci/of.c
> > +++ b/drivers/pci/of.c
> > @@ -633,3 +633,73 @@ int of_pci_get_max_link_speed(struct device_node *node)
> >  	return max_link_speed;
> >  }
> >  EXPORT_SYMBOL_GPL(of_pci_get_max_link_speed);
> > +
> > +/**
> > + * of_pci_get_slot_power_limit - Parses the "slot-power-limit-milliwatt"
> > + *				 property.
> > + *
> > + * @node: device tree node with the slot power limit information
> > + * @slot_power_limit_value: pointer where the value should be stored in PCIe
> > + *			    Slot Capabilities Register format
> > + * @slot_power_limit_scale: pointer where the scale should be stored in PCIe
> > + *			    Slot Capabilities Register format
> > + *
> > + * Returns the slot power limit in milliwatts and if @slot_power_limit_value
> > + * and @slot_power_limit_scale pointers are non-NULL, fills in the value and
> > + * scale in format used by PCIe Slot Capabilities Register.
> > + *
> > + * If the property is not found or is invalid, returns 0.
> > + */
> > +u32 of_pci_get_slot_power_limit(struct device_node *node,
> > +				u8 *slot_power_limit_value,
> > +				u8 *slot_power_limit_scale)
> > +{
> > +	u32 slot_power_limit_mw;
> > +	u8 value, scale;
> > +
> > +	if (of_property_read_u32(node, "slot-power-limit-milliwatt",
> > +				 &slot_power_limit_mw))
> > +		slot_power_limit_mw = 0;
> > +
> > +	/* Calculate Slot Power Limit Value and Slot Power Limit Scale */
> > +	if (slot_power_limit_mw == 0) {
> > +		value = 0x00;
> > +		scale = 0;
> > +	} else if (slot_power_limit_mw <= 255) {
> > +		value = slot_power_limit_mw;
> > +		scale = 3;
> > +	} else if (slot_power_limit_mw <= 255*10) {
> > +		value = slot_power_limit_mw / 10;
> > +		scale = 2;
> > +		slot_power_limit_mw = slot_power_limit_mw / 10 * 10;
> > +	} else if (slot_power_limit_mw <= 255*100) {
> > +		value = slot_power_limit_mw / 100;
> > +		scale = 1;
> > +		slot_power_limit_mw = slot_power_limit_mw / 100 * 100;
> > +	} else if (slot_power_limit_mw <= 239*1000) {
> > +		value = slot_power_limit_mw / 1000;
> > +		scale = 0;
> > +		slot_power_limit_mw = slot_power_limit_mw / 1000 * 1000;
> > +	} else if (slot_power_limit_mw < 250*1000) {
> > +		value = 0xEF;
> > +		scale = 0;
> > +		slot_power_limit_mw = 239*1000;
> > +	} else if (slot_power_limit_mw <= 600*1000) {
> > +		value = 0xF0 + (slot_power_limit_mw / 1000 - 250) / 25;
> > +		scale = 0;
> > +		slot_power_limit_mw = slot_power_limit_mw / (1000*25) * (1000*25);
> > +	} else {
> > +		value = 0xFE;
> > +		scale = 0;
> > +		slot_power_limit_mw = 600*1000;
> > +	}
> > +
> > +	if (slot_power_limit_value)
> > +		*slot_power_limit_value = value;
> > +
> > +	if (slot_power_limit_scale)
> > +		*slot_power_limit_scale = scale;
> > +
> > +	return slot_power_limit_mw;
> > +}
> > +EXPORT_SYMBOL_GPL(of_pci_get_slot_power_limit);
> > diff --git a/drivers/pci/pci.h b/drivers/pci/pci.h
> > index 3d60cabde1a1..e10cdec6c56e 100644
> > --- a/drivers/pci/pci.h
> > +++ b/drivers/pci/pci.h
> > @@ -627,6 +627,9 @@ struct device_node;
> >  int of_pci_parse_bus_range(struct device_node *node, struct resource *res);
> >  int of_get_pci_domain_nr(struct device_node *node);
> >  int of_pci_get_max_link_speed(struct device_node *node);
> > +u32 of_pci_get_slot_power_limit(struct device_node *node,
> > +				u8 *slot_power_limit_value,
> > +				u8 *slot_power_limit_scale);
> >  void pci_set_of_node(struct pci_dev *dev);
> >  void pci_release_of_node(struct pci_dev *dev);
> >  void pci_set_bus_of_node(struct pci_bus *bus);
> > @@ -653,6 +656,18 @@ of_pci_get_max_link_speed(struct device_node *node)
> >  	return -EINVAL;
> >  }
> >  
> > +static inline u32
> > +of_pci_get_slot_power_limit(struct device_node *node,
> > +			    u8 *slot_power_limit_value,
> > +			    u8 *slot_power_limit_scale)
> > +{
> > +	if (slot_power_limit_value)
> > +		*slot_power_limit_value = 0;
> > +	if (slot_power_limit_scale)
> > +		*slot_power_limit_scale = 0;
> > +	return 0;
> > +}
> > +
> >  static inline void pci_set_of_node(struct pci_dev *dev) { }
> >  static inline void pci_release_of_node(struct pci_dev *dev) { }
> >  static inline void pci_set_bus_of_node(struct pci_bus *bus) { }
> > -- 
> > 2.20.1
> > 
> > 
> > _______________________________________________
> > linux-arm-kernel mailing list
> > linux-arm-kernel@lists.infradead.org
> > http://lists.infradead.org/mailman/listinfo/linux-arm-kernel

Re: [PATCH v5 3/4] PCI: Add function for parsing 'slot-power-limit-milliwatt' DT property

[Lorenzo Pieralisi]

On Thu, Apr 21, 2022 at 10:14:13PM +0200, Pali Rohár wrote:
> On Wednesday 13 April 2022 15:24:33 Bjorn Helgaas wrote:
> > On Tue, Apr 12, 2022 at 11:49:45AM +0200, Pali Rohár wrote:
> > > Add function of_pci_get_slot_power_limit(), which parses the
> > > 'slot-power-limit-milliwatt' DT property, returning the value in
> > > milliwatts and in format ready for the PCIe Slot Capabilities Register.
> > > 
> > > Signed-off-by: Pali Rohár <pali@kernel.org>
> > > Signed-off-by: Marek Behún <kabel@kernel.org>
> > > Reviewed-by: Rob Herring <robh@kernel.org>
> > 
> > Looks good to me!  Thank you!
> > 
> > Reviewed-by: Bjorn Helgaas <bhelgaas@google.com>
> 
> Perfect!
> 
> Lorenzo, is this patch series OK now for merging?

Yes it is. I have a related question (ie how to check whether a binding
has been accepted into the DT schema) but I will sort that out with
Rob.

Thanks,
Lorenzo

> > > ---
> > > Changes in v4:
> > > * Set 239 W when DT slot-power-limit-milliwatt is between 239 W and 250 W
> > > * Fix returning power limit value
> > > Changes in v3:
> > > * Set 600 W when DT slot-power-limit-milliwatt > 600 W
> > > Changes in v2:
> > > * Added support for PCIe 6.0 slot power limit encodings
> > > * Round down slot power limit value
> > > ---
> > >  drivers/pci/of.c  | 70 +++++++++++++++++++++++++++++++++++++++++++++++
> > >  drivers/pci/pci.h | 15 ++++++++++
> > >  2 files changed, 85 insertions(+)
> > > 
> > > diff --git a/drivers/pci/of.c b/drivers/pci/of.c
> > > index cb2e8351c2cc..6c1b81304665 100644
> > > --- a/drivers/pci/of.c
> > > +++ b/drivers/pci/of.c
> > > @@ -633,3 +633,73 @@ int of_pci_get_max_link_speed(struct device_node *node)
> > >  	return max_link_speed;
> > >  }
> > >  EXPORT_SYMBOL_GPL(of_pci_get_max_link_speed);
> > > +
> > > +/**
> > > + * of_pci_get_slot_power_limit - Parses the "slot-power-limit-milliwatt"
> > > + *				 property.
> > > + *
> > > + * @node: device tree node with the slot power limit information
> > > + * @slot_power_limit_value: pointer where the value should be stored in PCIe
> > > + *			    Slot Capabilities Register format
> > > + * @slot_power_limit_scale: pointer where the scale should be stored in PCIe
> > > + *			    Slot Capabilities Register format
> > > + *
> > > + * Returns the slot power limit in milliwatts and if @slot_power_limit_value
> > > + * and @slot_power_limit_scale pointers are non-NULL, fills in the value and
> > > + * scale in format used by PCIe Slot Capabilities Register.
> > > + *
> > > + * If the property is not found or is invalid, returns 0.
> > > + */
> > > +u32 of_pci_get_slot_power_limit(struct device_node *node,
> > > +				u8 *slot_power_limit_value,
> > > +				u8 *slot_power_limit_scale)
> > > +{
> > > +	u32 slot_power_limit_mw;
> > > +	u8 value, scale;
> > > +
> > > +	if (of_property_read_u32(node, "slot-power-limit-milliwatt",
> > > +				 &slot_power_limit_mw))
> > > +		slot_power_limit_mw = 0;
> > > +
> > > +	/* Calculate Slot Power Limit Value and Slot Power Limit Scale */
> > > +	if (slot_power_limit_mw == 0) {
> > > +		value = 0x00;
> > > +		scale = 0;
> > > +	} else if (slot_power_limit_mw <= 255) {
> > > +		value = slot_power_limit_mw;
> > > +		scale = 3;
> > > +	} else if (slot_power_limit_mw <= 255*10) {
> > > +		value = slot_power_limit_mw / 10;
> > > +		scale = 2;
> > > +		slot_power_limit_mw = slot_power_limit_mw / 10 * 10;
> > > +	} else if (slot_power_limit_mw <= 255*100) {
> > > +		value = slot_power_limit_mw / 100;
> > > +		scale = 1;
> > > +		slot_power_limit_mw = slot_power_limit_mw / 100 * 100;
> > > +	} else if (slot_power_limit_mw <= 239*1000) {
> > > +		value = slot_power_limit_mw / 1000;
> > > +		scale = 0;
> > > +		slot_power_limit_mw = slot_power_limit_mw / 1000 * 1000;
> > > +	} else if (slot_power_limit_mw < 250*1000) {
> > > +		value = 0xEF;
> > > +		scale = 0;
> > > +		slot_power_limit_mw = 239*1000;
> > > +	} else if (slot_power_limit_mw <= 600*1000) {
> > > +		value = 0xF0 + (slot_power_limit_mw / 1000 - 250) / 25;
> > > +		scale = 0;
> > > +		slot_power_limit_mw = slot_power_limit_mw / (1000*25) * (1000*25);
> > > +	} else {
> > > +		value = 0xFE;
> > > +		scale = 0;
> > > +		slot_power_limit_mw = 600*1000;
> > > +	}
> > > +
> > > +	if (slot_power_limit_value)
> > > +		*slot_power_limit_value = value;
> > > +
> > > +	if (slot_power_limit_scale)
> > > +		*slot_power_limit_scale = scale;
> > > +
> > > +	return slot_power_limit_mw;
> > > +}
> > > +EXPORT_SYMBOL_GPL(of_pci_get_slot_power_limit);
> > > diff --git a/drivers/pci/pci.h b/drivers/pci/pci.h
> > > index 3d60cabde1a1..e10cdec6c56e 100644
> > > --- a/drivers/pci/pci.h
> > > +++ b/drivers/pci/pci.h
> > > @@ -627,6 +627,9 @@ struct device_node;
> > >  int of_pci_parse_bus_range(struct device_node *node, struct resource *res);
> > >  int of_get_pci_domain_nr(struct device_node *node);
> > >  int of_pci_get_max_link_speed(struct device_node *node);
> > > +u32 of_pci_get_slot_power_limit(struct device_node *node,
> > > +				u8 *slot_power_limit_value,
> > > +				u8 *slot_power_limit_scale);
> > >  void pci_set_of_node(struct pci_dev *dev);
> > >  void pci_release_of_node(struct pci_dev *dev);
> > >  void pci_set_bus_of_node(struct pci_bus *bus);
> > > @@ -653,6 +656,18 @@ of_pci_get_max_link_speed(struct device_node *node)
> > >  	return -EINVAL;
> > >  }
> > >  
> > > +static inline u32
> > > +of_pci_get_slot_power_limit(struct device_node *node,
> > > +			    u8 *slot_power_limit_value,
> > > +			    u8 *slot_power_limit_scale)
> > > +{
> > > +	if (slot_power_limit_value)
> > > +		*slot_power_limit_value = 0;
> > > +	if (slot_power_limit_scale)
> > > +		*slot_power_limit_scale = 0;
> > > +	return 0;
> > > +}
> > > +
> > >  static inline void pci_set_of_node(struct pci_dev *dev) { }
> > >  static inline void pci_release_of_node(struct pci_dev *dev) { }
> > >  static inline void pci_set_bus_of_node(struct pci_bus *bus) { }
> > > -- 
> > > 2.20.1
> > > 
> > > 
> > > _______________________________________________
> > > linux-arm-kernel mailing list
> > > linux-arm-kernel@lists.infradead.org
> > > http://lists.infradead.org/mailman/listinfo/linux-arm-kernel

[PATCH v5 4/4] PCI: mvebu: Add support for sending Set_Slot_Power_Limit message

[Pali Rohár]

If DT supplies the 'slot-power-limit-milliwatt' property, program
the value in the Slot Power Limit in the Slot Capabilities register
and program the Root Port to send a Set_Slot_Power_Limit Message
when the Link transitions to DL_Up.

Signed-off-by: Pali Rohár <pali@kernel.org>
Reviewed-by: Rob Herring <robh@kernel.org>
---
Changes in v5:
* Fix compile error due to wrong patch rebasing
Changes in v2:
* Fix handling of slot power limit with scale x1.0 (0x00 value)
* Use FIELD_PREP instead of _SHIFT macros
* Changed commit message to Bjorn's suggestion
* Changed comments in the code to match PCIe spec
* Preserve user settings of PCI_EXP_SLTCTL_ASPL_DISABLE bit
---
 drivers/pci/controller/pci-mvebu.c | 97 ++++++++++++++++++++++++++++--
 1 file changed, 92 insertions(+), 5 deletions(-)

diff --git a/drivers/pci/controller/pci-mvebu.c b/drivers/pci/controller/pci-mvebu.c
index a75d2b9196f9..a9678d658c2a 100644
--- a/drivers/pci/controller/pci-mvebu.c
+++ b/drivers/pci/controller/pci-mvebu.c
@@ -8,6 +8,7 @@
 #include <linux/kernel.h>
 #include <linux/module.h>
 #include <linux/pci.h>
+#include <linux/bitfield.h>
 #include <linux/clk.h>
 #include <linux/delay.h>
 #include <linux/gpio.h>
@@ -66,6 +67,12 @@
 #define  PCIE_STAT_BUS                  0xff00
 #define  PCIE_STAT_DEV                  0x1f0000
 #define  PCIE_STAT_LINK_DOWN		BIT(0)
+#define PCIE_SSPL_OFF		0x1a0c
+#define  PCIE_SSPL_VALUE_SHIFT		0
+#define  PCIE_SSPL_VALUE_MASK		GENMASK(7, 0)
+#define  PCIE_SSPL_SCALE_SHIFT		8
+#define  PCIE_SSPL_SCALE_MASK		GENMASK(9, 8)
+#define  PCIE_SSPL_ENABLE		BIT(16)
 #define PCIE_RC_RTSTA		0x1a14
 #define PCIE_DEBUG_CTRL         0x1a60
 #define  PCIE_DEBUG_SOFT_RESET		BIT(20)
@@ -111,6 +118,8 @@ struct mvebu_pcie_port {
 	struct mvebu_pcie_window iowin;
 	u32 saved_pcie_stat;
 	struct resource regs;
+	u8 slot_power_limit_value;
+	u8 slot_power_limit_scale;
 	struct irq_domain *intx_irq_domain;
 	raw_spinlock_t irq_lock;
 	int intx_irq;
@@ -239,7 +248,7 @@ static void mvebu_pcie_setup_wins(struct mvebu_pcie_port *port)
 
 static void mvebu_pcie_setup_hw(struct mvebu_pcie_port *port)
 {
-	u32 ctrl, lnkcap, cmd, dev_rev, unmask;
+	u32 ctrl, lnkcap, cmd, dev_rev, unmask, sspl;
 
 	/* Setup PCIe controller to Root Complex mode. */
 	ctrl = mvebu_readl(port, PCIE_CTRL_OFF);
@@ -292,6 +301,20 @@ static void mvebu_pcie_setup_hw(struct mvebu_pcie_port *port)
 	/* Point PCIe unit MBUS decode windows to DRAM space. */
 	mvebu_pcie_setup_wins(port);
 
+	/*
+	 * Program Root Port to automatically send Set_Slot_Power_Limit
+	 * PCIe Message when changing status from Dl_Down to Dl_Up and valid
+	 * slot power limit was specified.
+	 */
+	sspl = mvebu_readl(port, PCIE_SSPL_OFF);
+	sspl &= ~(PCIE_SSPL_VALUE_MASK | PCIE_SSPL_SCALE_MASK | PCIE_SSPL_ENABLE);
+	if (port->slot_power_limit_value) {
+		sspl |= port->slot_power_limit_value << PCIE_SSPL_VALUE_SHIFT;
+		sspl |= port->slot_power_limit_scale << PCIE_SSPL_SCALE_SHIFT;
+		sspl |= PCIE_SSPL_ENABLE;
+	}
+	mvebu_writel(port, sspl, PCIE_SSPL_OFF);
+
 	/* Mask all interrupt sources. */
 	mvebu_writel(port, ~PCIE_INT_ALL_MASK, PCIE_INT_UNMASK_OFF);
 
@@ -628,9 +651,24 @@ mvebu_pci_bridge_emul_pcie_conf_read(struct pci_bridge_emul *bridge,
 			  (PCI_EXP_LNKSTA_DLLLA << 16) : 0);
 		break;
 
-	case PCI_EXP_SLTCTL:
-		*value = PCI_EXP_SLTSTA_PDS << 16;
+	case PCI_EXP_SLTCTL: {
+		u16 slotctl = le16_to_cpu(bridge->pcie_conf.slotctl);
+		u16 slotsta = le16_to_cpu(bridge->pcie_conf.slotsta);
+		u32 val = 0;
+		/*
+		 * When slot power limit was not specified in DT then
+		 * ASPL_DISABLE bit is stored only in emulated config space.
+		 * Otherwise reflect status of PCIE_SSPL_ENABLE bit in HW.
+		 */
+		if (!port->slot_power_limit_value)
+			val |= slotctl & PCI_EXP_SLTCTL_ASPL_DISABLE;
+		else if (!(mvebu_readl(port, PCIE_SSPL_OFF) & PCIE_SSPL_ENABLE))
+			val |= PCI_EXP_SLTCTL_ASPL_DISABLE;
+		/* This callback is 32-bit and in high bits is slot status. */
+		val |= slotsta << 16;
+		*value = val;
 		break;
+	}
 
 	case PCI_EXP_RTSTA:
 		*value = mvebu_readl(port, PCIE_RC_RTSTA);
@@ -774,6 +812,22 @@ mvebu_pci_bridge_emul_pcie_conf_write(struct pci_bridge_emul *bridge,
 		mvebu_writel(port, new, PCIE_CAP_PCIEXP + PCI_EXP_LNKCTL);
 		break;
 
+	case PCI_EXP_SLTCTL:
+		/*
+		 * Allow to change PCIE_SSPL_ENABLE bit only when slot power
+		 * limit was specified in DT and configured into HW.
+		 */
+		if ((mask & PCI_EXP_SLTCTL_ASPL_DISABLE) &&
+		    port->slot_power_limit_value) {
+			u32 sspl = mvebu_readl(port, PCIE_SSPL_OFF);
+			if (new & PCI_EXP_SLTCTL_ASPL_DISABLE)
+				sspl &= ~PCIE_SSPL_ENABLE;
+			else
+				sspl |= PCIE_SSPL_ENABLE;
+			mvebu_writel(port, sspl, PCIE_SSPL_OFF);
+		}
+		break;
+
 	case PCI_EXP_RTSTA:
 		/*
 		 * PME Status bit in Root Status Register (PCIE_RC_RTSTA)
@@ -868,8 +922,26 @@ static int mvebu_pci_bridge_emul_init(struct mvebu_pcie_port *port)
 	/*
 	 * Older mvebu hardware provides PCIe Capability structure only in
 	 * version 1. New hardware provides it in version 2.
+	 * Enable slot support which is emulated.
 	 */
-	bridge->pcie_conf.cap = cpu_to_le16(pcie_cap_ver);
+	bridge->pcie_conf.cap = cpu_to_le16(pcie_cap_ver | PCI_EXP_FLAGS_SLOT);
+
+	/*
+	 * Set Presence Detect State bit permanently as there is no support for
+	 * unplugging PCIe card from the slot. Assume that PCIe card is always
+	 * connected in slot.
+	 *
+	 * Set physical slot number to port+1 as mvebu ports are indexed from
+	 * zero and zero value is reserved for ports within the same silicon
+	 * as Root Port which is not mvebu case.
+	 *
+	 * Also set correct slot power limit.
+	 */
+	bridge->pcie_conf.slotcap = cpu_to_le32(
+		FIELD_PREP(PCI_EXP_SLTCAP_SPLV, port->slot_power_limit_value) |
+		FIELD_PREP(PCI_EXP_SLTCAP_SPLS, port->slot_power_limit_scale) |
+		FIELD_PREP(PCI_EXP_SLTCAP_PSN, port->port+1));
+	bridge->pcie_conf.slotsta = cpu_to_le16(PCI_EXP_SLTSTA_PDS);
 
 	bridge->subsystem_vendor_id = ssdev_id & 0xffff;
 	bridge->subsystem_id = ssdev_id >> 16;
@@ -1191,6 +1263,7 @@ static int mvebu_pcie_parse_port(struct mvebu_pcie *pcie,
 {
 	struct device *dev = &pcie->pdev->dev;
 	enum of_gpio_flags flags;
+	u32 slot_power_limit;
 	int reset_gpio, ret;
 	u32 num_lanes;
 
@@ -1291,6 +1364,15 @@ static int mvebu_pcie_parse_port(struct mvebu_pcie *pcie,
 		port->reset_gpio = gpio_to_desc(reset_gpio);
 	}
 
+	slot_power_limit = of_pci_get_slot_power_limit(child,
+				&port->slot_power_limit_value,
+				&port->slot_power_limit_scale);
+	if (slot_power_limit)
+		dev_info(dev, "%s: Slot power limit %u.%uW\n",
+			 port->name,
+			 slot_power_limit / 1000,
+			 (slot_power_limit / 100) % 10);
+
 	port->clk = of_clk_get_by_name(child, NULL);
 	if (IS_ERR(port->clk)) {
 		dev_err(dev, "%s: cannot get clock\n", port->name);
@@ -1587,7 +1669,7 @@ static int mvebu_pcie_remove(struct platform_device *pdev)
 {
 	struct mvebu_pcie *pcie = platform_get_drvdata(pdev);
 	struct pci_host_bridge *bridge = pci_host_bridge_from_priv(pcie);
-	u32 cmd;
+	u32 cmd, sspl;
 	int i;
 
 	/* Remove PCI bus with all devices. */
@@ -1624,6 +1706,11 @@ static int mvebu_pcie_remove(struct platform_device *pdev)
 		/* Free config space for emulated root bridge. */
 		pci_bridge_emul_cleanup(&port->bridge);
 
+		/* Disable sending Set_Slot_Power_Limit PCIe Message. */
+		sspl = mvebu_readl(port, PCIE_SSPL_OFF);
+		sspl &= ~(PCIE_SSPL_VALUE_MASK | PCIE_SSPL_SCALE_MASK | PCIE_SSPL_ENABLE);
+		mvebu_writel(port, sspl, PCIE_SSPL_OFF);
+
 		/* Disable and clear BARs and windows. */
 		mvebu_pcie_disable_wins(port);
 
-- 
2.20.1

Re: (subset) [PATCH v5 0/4] PCI: mvebu: Slot support

[Lorenzo Pieralisi]

On Tue, 12 Apr 2022 11:49:42 +0200, Pali Rohár wrote:
> This patch series add slot support to pci-mvebu.c driver.
> 
> Changes in v5:
> * Fix compile error due to wrong patch rebasing
> 
> Changes in v4:
> * Set 239 W when DT slot-power-limit-milliwatt is between 239 W and 250 W
> * Fix returning power limit value
> 
> [...]

Dropped patch [2] since it is not needed.

Applied to pci/power-slot, thanks!

[1/4] PCI: Add PCI_EXP_SLTCTL_ASPL_DISABLE macro
      https://git.kernel.org/lpieralisi/pci/c/e8e7fbb6a3
[3/4] PCI: Add function for parsing 'slot-power-limit-milliwatt' DT property
      https://git.kernel.org/lpieralisi/pci/c/35662423fb
[4/4] PCI: mvebu: Add support for sending Set_Slot_Power_Limit message
      https://git.kernel.org/lpieralisi/pci/c/0d5b8c2985

Thanks,
Lorenzo