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

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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: Pali Rohár <pali@kernel.org>
Signed-off-by: Marek Behún <kabel@kernel.org>
Signed-off-by: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
Reviewed-by: Rob Herring <robh@kernel.org>
Reviewed-by: Bjorn Helgaas <bhelgaas@google.com>
This commit is contained in:
Pali Rohár 2022-04-12 11:49:45 +02:00 committed by Lorenzo Pieralisi
parent e8e7fbb6a3
commit 35662423fb
2 changed files with 85 additions and 0 deletions
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70
drivers/pci/of.c
View File

@ -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);

15
drivers/pci/pci.h
View File

@ -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) { }