Commit 35662423 authored by Pali Rohár's avatar Pali Rohár Committed by Lorenzo Pieralisi
Browse files

PCI: Add function for parsing 'slot-power-limit-milliwatt' DT property 

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.

Link: https://lore.kernel.org/r/20220412094946.27069-4-pali@kernel.org


Signed-off-by: default avatarPali Rohár <pali@kernel.org>
Signed-off-by: default avatarMarek Behún <kabel@kernel.org>
Signed-off-by: default avatarLorenzo Pieralisi <lorenzo.pieralisi@arm.com>
Reviewed-by: default avatarRob Herring <robh@kernel.org>
Reviewed-by: default avatarBjorn Helgaas <bhelgaas@google.com>
parent e8e7fbb6

drivers/pci/of.c

+70 −0
Original line number Diff line number Diff line
@@ -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);

drivers/pci/pci.h

+15 −0
Original line number Diff line number Diff line
@@ -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) { }