alistair23-linux/Documentation/devicetree/bindings/pci/fsl,imx6q-pcie.txt

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* 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"
- 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
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>
2016-04-19 18:42:07 -06:00
- 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";
};