linux/Documentation/devicetree/bindings/pci/fsl,imx6q-pcie.txt

62 lines
2.7 KiB
Plaintext
Raw Normal View History

* Freescale i.MX6 PCIe interface
This PCIe host controller is based on the Synopsis Designware PCIe IP
and thus inherits all the common properties defined in designware-pcie.txt.
Required properties:
- compatible: "fsl,imx6q-pcie", "fsl,imx6sx-pcie", "fsl,imx6qp-pcie"
- reg: base address and length of the PCIe controller
- interrupts: A list of interrupt outputs of the controller. Must contain an
entry for each entry in the interrupt-names property.
- interrupt-names: Must include the following entries:
- "msi": The interrupt that is asserted when an MSI is received
- clock-names: Must include the following additional entries:
- "pcie_phy"
Optional properties:
- fsl,tx-deemph-gen1: Gen1 De-emphasis value. Default: 0
- fsl,tx-deemph-gen2-3p5db: Gen2 (3.5db) De-emphasis value. Default: 0
- fsl,tx-deemph-gen2-6db: Gen2 (6db) De-emphasis value. Default: 20
- fsl,tx-swing-full: Gen2 TX SWING FULL value. Default: 127
- fsl,tx-swing-low: TX launch amplitude swing_low value. Default: 127
- fsl,max-link-speed: Specify PCI gen for link capability. Must be '2' for
gen2, otherwise will default to gen1. Note that the IMX6 LVDS clock outputs
do not meet gen2 jitter requirements and thus for gen2 capability a gen2
compliant clock generator should be used and configured.
PCI: imx6: Add reset-gpio-active-high boolean property to DT Currently the reset-gpio DT property which controls the PCI bus device reset signal defaults to active-low reset sequence (L=reset state, H=operation state) plus the code in reset function isn't GPIO polarity aware - it doesn't matter if the defined reset-gpio is active-low or active-high, it will always result into active-low reset sequence. I've tried to fix it properly and change the reset-gpio reset sequence to be polarity-aware, but this patch has been accepted and then reverted as it has introduced few backward incompatible issues: 1. Some DTBs, for example, imx6qdl-sabresd, don't define reset-gpio polarity correctly: reset-gpio = <&gpio7 12 0>; which means that it's defined as active-high, but in reality it's active-low; thus it wouldn't work without a DTS fix. 2. The logic in the reset function is inverted: gpio_set_value_cansleep(imx6_pcie->reset_gpio, 0) msleep(100); gpio_set_value_cansleep(imx6_pcie->reset_gpio, 1); so even if some of the i.MX6 boards had reset-gpio polarity defined correctly in their DTSes, they would stop working. As we can't break old DTBs, we can't fix them, so we need to introduce this new DT reset-gpio-active-high boolean property so we can support boards with active-high reset sequence. This active-high reset sequence is for example needed on Apalis SoMs, where GPIO1_IO28, used to PCIe reset is not connected directly to PERST# PCIe signal, but it's ORed with RESETBMCU coming off the PMIC, and thus is inverted, active-high. Tested-by: Tim Harvey <tharvey@gateworks.com> # Gateworks Ventana boards (which have active-low PERST#) Signed-off-by: Petr Štetiar <ynezz@true.cz> Signed-off-by: Bjorn Helgaas <bhelgaas@google.com> Reviewed-by: Lucas Stach <l.stach@pengutronix.de> Acked-by: Rob Herring <robh@kernel.org>
2016-04-20 00:42:07 +00:00
- reset-gpio: Should specify the GPIO for controlling the PCI bus device reset
signal. It's not polarity aware and defaults to active-low reset sequence
(L=reset state, H=operation state).
- reset-gpio-active-high: If present then the reset sequence using the GPIO
specified in the "reset-gpio" property is reversed (H=reset state,
L=operation state).
Additional required properties for imx6sx-pcie:
- clock names: Must include the following additional entries:
- "pcie_inbound_axi"
Example:
pcie@0x01000000 {
compatible = "fsl,imx6q-pcie", "snps,dw-pcie";
reg = <0x01ffc000 0x04000>,
<0x01f00000 0x80000>;
reg-names = "dbi", "config";
#address-cells = <3>;
#size-cells = <2>;
device_type = "pci";
ranges = <0x00000800 0 0x01f00000 0x01f00000 0 0x00080000
0x81000000 0 0 0x01f80000 0 0x00010000
0x82000000 0 0x01000000 0x01000000 0 0x00f00000>;
num-lanes = <1>;
interrupts = <GIC_SPI 120 IRQ_TYPE_LEVEL_HIGH>;
interrupt-names = "msi";
#interrupt-cells = <1>;
interrupt-map-mask = <0 0 0 0x7>;
interrupt-map = <0 0 0 1 &intc GIC_SPI 123 IRQ_TYPE_LEVEL_HIGH>,
<0 0 0 2 &intc GIC_SPI 122 IRQ_TYPE_LEVEL_HIGH>,
<0 0 0 3 &intc GIC_SPI 121 IRQ_TYPE_LEVEL_HIGH>,
<0 0 0 4 &intc GIC_SPI 120 IRQ_TYPE_LEVEL_HIGH>;
clocks = <&clks 144>, <&clks 206>, <&clks 189>;
clock-names = "pcie", "pcie_bus", "pcie_phy";
};