From: "Pali Rohár" <pali@kernel.org>
To: "Lorenzo Pieralisi" <lorenzo.pieralisi@arm.com>,
"Bjorn Helgaas" <bhelgaas@google.com>,
"Rob Herring" <robh+dt@kernel.org>,
"Andrew Lunn" <andrew@lunn.ch>,
"Thomas Petazzoni" <thomas.petazzoni@bootlin.com>,
"Krzysztof Wilczyński" <kw@linux.com>,
"Marek Behún" <kabel@kernel.org>,
"Russell King" <rmk+kernel@armlinux.org.uk>
Cc: linux-pci@vger.kernel.org, linux-arm-kernel@lists.infradead.org,
linux-kernel@vger.kernel.org
Subject: [PATCH v5 3/4] PCI: Add function for parsing 'slot-power-limit-milliwatt' DT property
Date: Tue, 12 Apr 2022 11:49:45 +0200 [thread overview]
Message-ID: <20220412094946.27069-4-pali@kernel.org> (raw)
In-Reply-To: <20220412094946.27069-1-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>
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
next prev parent reply other threads:[~2022-04-12 10:56 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-04-12 9:49 [PATCH v5 0/4] PCI: mvebu: Slot support Pali Rohár
2022-04-12 9:49 ` [PATCH v5 1/4] PCI: Add PCI_EXP_SLTCTL_ASPL_DISABLE macro Pali Rohár
2022-04-12 9:49 ` [PATCH v5 2/4] dt-bindings: Add 'slot-power-limit-milliwatt' PCIe port property Pali Rohár
2022-04-12 9:49 ` Pali Rohár [this message]
2022-04-13 20:24 ` [PATCH v5 3/4] PCI: Add function for parsing 'slot-power-limit-milliwatt' DT property Bjorn Helgaas
2022-04-21 20:14 ` Pali Rohár
2022-04-22 10:06 ` Lorenzo Pieralisi
2022-04-12 9:49 ` [PATCH v5 4/4] PCI: mvebu: Add support for sending Set_Slot_Power_Limit message Pali Rohár
2022-04-25 9:59 ` (subset) [PATCH v5 0/4] PCI: mvebu: Slot support Lorenzo Pieralisi
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