Re: [PATCH dt + pci 2/2] PCI: Add function for parsing `slot-power-limit-milliwatt` DT property

Marek Behún
2022-01-07T18:04:45Z

Hello Bjorn,

the property was merged into dt-schema, see
https://github.com/devicetree-org/dt-schema/commit/7b2d7c521ba55903846cbba00518e1c4038699b4
so we don't need to add it to linux git anymore.

Since the property is documented id dt-schema, can we now merge this
patch, which adds the of_pci_get_slot_power_limit() function? Both
aardvark and mvebu driver will use this function.

Marek

On Sun, 31 Oct 2021 16:07:06 +0100
Marek Behún <kabel@kernel.org> wrote:

> From: Pali Rohár <pali@kernel.org>
>
> 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>
> ---
> drivers/pci/of.c | 64 +++++++++++++++++++++++++++++++++++++++++++++++
> drivers/pci/pci.h | 15 +++++++++++
> 2 files changed, 79 insertions(+)
>
> diff --git a/drivers/pci/of.c b/drivers/pci/of.c
> index d84381ce82b5..9c1a38d5dd99 100644
> --- a/drivers/pci/of.c
> +++ b/drivers/pci/of.c
> @@ -627,3 +627,67 @@ 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;
> + u8 value, scale;
> +
> + if (of_property_read_u32(node, "slot-power-limit-milliwatt",
> + &slot_power_limit))
> + slot_power_limit = 0;
> +
> + /* Calculate Slot Power Limit Value and Slot Power Limit Scale */
> + if (slot_power_limit == 0) {
> + value = 0x00;
> + scale = 0;
> + } else if (slot_power_limit <= 255) {
> + value = slot_power_limit;
> + scale = 3;
> + } else if (slot_power_limit <= 255*10) {
> + value = slot_power_limit / 10;
> + scale = 2;
> + } else if (slot_power_limit <= 255*100) {
> + value = slot_power_limit / 100;
> + scale = 1;
> + } else if (slot_power_limit <= 239*1000) {
> + value = slot_power_limit / 1000;
> + scale = 0;
> + } else if (slot_power_limit <= 250*1000) {
> + value = 0xF0;
> + scale = 0;
> + } else if (slot_power_limit <= 275*1000) {
> + value = 0xF1;
> + scale = 0;
> + } else {
> + value = 0xF2;
> + scale = 0;
> + }
> +
> + if (slot_power_limit_value)
> + *slot_power_limit_value = value;
> +
> + if (slot_power_limit_scale)
> + *slot_power_limit_scale = scale;
> +
> + return slot_power_limit;
> +}
> +EXPORT_SYMBOL_GPL(of_pci_get_slot_power_limit);
> diff --git a/drivers/pci/pci.h b/drivers/pci/pci.h
> index 1cce56c2aea0..9352278141be 100644
> --- a/drivers/pci/pci.h
> +++ b/drivers/pci/pci.h
> @@ -665,6 +665,9 @@ 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);
> @@ -691,6 +694,18 @@ 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) { }