Added a function for calculating a PCI device's total link bandwidth
capabilities. This function queries for the device link speed and
width, multiplies them and applies encoding overhead for the different
PCIe generations.
Signed-off-by: Tal Gilboa <talgi@xxxxxxxxxxxx>
Reviewed-by: Tariq Toukan <tariqt@xxxxxxxxxxxx>
---
drivers/pci/pci.c | 22 ++++++++++++++++++++++
include/linux/pci.h | 12 ++++++++++++
2 files changed, 34 insertions(+)
diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c
index 90a6cf2..553d8f3 100644
--- a/drivers/pci/pci.c
+++ b/drivers/pci/pci.c
@@ -5212,6 +5212,28 @@ int pcie_get_width_cap(struct pci_dev *dev, enum pcie_link_width *width)
EXPORT_SYMBOL(pcie_get_width_cap);
/**
+ * pcie_bandwidth_capable - Calculates a PCI device's link bandwidth capability
+ * @dev: PCI device
+ * @speed: storage for link speed
+ * @width: storage for link width
+ *
+ * This function caculates a PCI device's link bandwidth by querying for its
+ * link speed and width, multiplying them, and applying encoding overhead.
+ */
+int pcie_bandwidth_capable(struct pci_dev *dev, enum pci_bus_speed *speed,
+ enum pcie_link_width *width)
+{
+ pcie_get_speed_cap(dev, speed);
+ pcie_get_width_cap(dev, width);
+
+ if (*speed == PCI_SPEED_UNKNOWN || *width == PCIE_LNK_WIDTH_UNKNOWN)
+ return 0;
+
+ return (*width) * PCIE_SPEED2MBS_ENC(*speed);
+}
+EXPORT_SYMBOL(pcie_bandwidth_capable);
+
+/**
* pci_select_bars - Make BAR mask from the type of resource
* @dev: the PCI device for which BAR mask is made
* @flags: resource type mask to be selected
diff --git a/include/linux/pci.h b/include/linux/pci.h
index 1e3d05f..9f57c45 100644
--- a/include/linux/pci.h
+++ b/include/linux/pci.h
@@ -265,6 +265,16 @@ enum pci_bus_speed {
(speed) == PCIE_SPEED_2_5GT ? "2.5 GT/s" : \
"Unknown speed")
+/**
+ * PCIe speed to Mb/s with encoding overhead:
+ * 20% for gen2, ~1.5% for gen3
+ */
+#define PCIE_SPEED2MBS_ENC(speed) \
+ ((speed) == PCIE_SPEED_8_0GT ? 7877 : \
+ (speed) == PCIE_SPEED_5_0GT ? 4000 : \
+ (speed) == PCIE_SPEED_2_5GT ? 2000 : \
+ 0)
+
struct pci_cap_saved_data {
u16 cap_nr;
bool cap_extended;
@@ -1090,6 +1100,8 @@ int pcie_get_minimum_link(struct pci_dev *dev, enum pci_bus_speed *speed,
enum pcie_link_width *width);
int pcie_get_speed_cap(struct pci_dev *dev, enum pci_bus_speed *speed);
int pcie_get_width_cap(struct pci_dev *dev, enum pcie_link_width *width);
+int pcie_bandwidth_capable(struct pci_dev *dev, enum pci_bus_speed *speed,
+ enum pcie_link_width *width);
void pcie_flr(struct pci_dev *dev);
int __pci_reset_function_locked(struct pci_dev *dev);
int pci_reset_function(struct pci_dev *dev);
--
1.8.3.1
