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@xxxxxxxxxx>
Signed-off-by: Marek Behún <kabel@xxxxxxxxxx>
Reviewed-by: Rob Herring <robh@xxxxxxxxxx>
Acked-by: Bjorn Helgaas <bhelgaas@xxxxxxxxxx>
---
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 cb2e8351c2cc..2b0c0a3641a8 100644
--- a/drivers/pci/of.c
+++ b/drivers/pci/of.c
@@ -633,3 +633,67 @@ 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 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
