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Commit f4e833ba authored by Leonard Crestez's avatar Leonard Crestez Committed by Lorenzo Pieralisi
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PCI: imx: Add PME_Turn_Off support 



When the root complex suspends it must send a PME_Turn_Off TLP.
Implement this by asserting the "turnoff" reset.

On imx7d this functionality is part of the System Reset Controller (SRC)
and is exposed through the linux reset-controller subsystem.

On imx6 equivalent bits are in the IOMUXC pinmux controller General
Purpose Register (GPR) area which the imx6-pcie driver accesses
directly.

This is only for imx7d right now but it's deliberately implemented as an
optional reset, ignoring the chip variant:
* Older dtbs won't have this reset so it will be ignored.
* Future chips might also expose this as a reset controller.

For example imx8m (not yet supported) has the exact same
PCIE_CTRL_APPS_TURNOFF bit in the same location.

Signed-off-by: default avatarLeonard Crestez <leonard.crestez@nxp.com>
[lorenzo.pieralisi@arm.com: updated commit log]
Signed-off-by: default avatarLorenzo Pieralisi <lorenzo.pieralisi@arm.com>
Reviewed-by: default avatarLucas Stach <l.stach@pengutronix.de>
parent 3aedf7e1

drivers/pci/controller/dwc/pci-imx6.c

+24 −0
Original line number Diff line number Diff line
@@ -50,6 +50,7 @@ struct imx6_pcie { 
	struct regmap		*iomuxc_gpr;

	struct reset_control	*pciephy_reset;

	struct reset_control	*apps_reset;

	struct reset_control	*turnoff_reset;

	enum imx6_pcie_variants variant;

	u32			tx_deemph_gen1;

	u32			tx_deemph_gen2_3p5db;
@@ -770,6 +771,21 @@ static void imx6_pcie_ltssm_disable(struct device *dev) 
	}

}



static void imx6_pcie_pm_turnoff(struct imx6_pcie *imx6_pcie)

{

	reset_control_assert(imx6_pcie->turnoff_reset);

	reset_control_deassert(imx6_pcie->turnoff_reset);



	/*

	 * Components with an upstream port must respond to

	 * PME_Turn_Off with PME_TO_Ack but we can't check.

	 *

	 * The standard recommends a 1-10ms timeout after which to

	 * proceed anyway as if acks were received.

	 */

	usleep_range(1000, 10000);

}



static void imx6_pcie_clk_disable(struct imx6_pcie *imx6_pcie)

{

	clk_disable_unprepare(imx6_pcie->pcie);
@@ -790,6 +806,7 @@ static int imx6_pcie_suspend_noirq(struct device *dev) 
	if (imx6_pcie->variant != IMX7D)

		return 0;



	imx6_pcie_pm_turnoff(imx6_pcie);

	imx6_pcie_clk_disable(imx6_pcie);

	imx6_pcie_ltssm_disable(dev);
@@ -917,6 +934,13 @@ static int imx6_pcie_probe(struct platform_device *pdev) 
		break;

	}



	/* Grab turnoff reset */

	imx6_pcie->turnoff_reset = devm_reset_control_get_optional_exclusive(dev, "turnoff");

	if (IS_ERR(imx6_pcie->turnoff_reset)) {

		dev_err(dev, "Failed to get TURNOFF reset control\n");

		return PTR_ERR(imx6_pcie->turnoff_reset);

	}



	/* Grab GPR config register range */

	imx6_pcie->iomuxc_gpr =

		 syscon_regmap_lookup_by_compatible("fsl,imx6q-iomuxc-gpr");