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SubjectRe: [PATCH v2 4/4] PCI: imx: Add PME_Turn_Off support
On Thu, Oct 04, 2018 at 04:34:30PM +0000, Leonard Crestez wrote:
> 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 SRC and exposed through the
> linux reset-controller subsystem. On imx6 equivalent bits are in the
> IOMUXC GPR area which the imx6-pcie driver accesses directly.

Nit: I am merging the series, please define what SRC and GPR are so
that I can update the commit log accordingly, it must be clear to
anyone reading it.

Thanks,
Lorenzo

> 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: Leonard Crestez <leonard.crestez@nxp.com>
> ---
> drivers/pci/controller/dwc/pci-imx6.c | 24 ++++++++++++++++++++++++
> 1 file changed, 24 insertions(+)
>
> diff --git a/drivers/pci/controller/dwc/pci-imx6.c b/drivers/pci/controller/dwc/pci-imx6.c
> index 6ba16fd1373c..2bf80f1ad852 100644
> --- a/drivers/pci/controller/dwc/pci-imx6.c
> +++ b/drivers/pci/controller/dwc/pci-imx6.c
> @@ -50,10 +50,11 @@ struct imx6_pcie {
> struct clk *pcie_inbound_axi;
> struct clk *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;
> u32 tx_deemph_gen2_6db;
> u32 tx_swing_full;
> @@ -812,10 +813,25 @@ static void imx6_pcie_ltssm_disable(struct device *dev)
> default:
> dev_err(dev, "ltssm_disable not supported\n");
> }
> }
>
> +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);
> clk_disable_unprepare(imx6_pcie->pcie_phy);
> clk_disable_unprepare(imx6_pcie->pcie_bus);
> @@ -832,10 +848,11 @@ static int imx6_pcie_suspend_noirq(struct device *dev)
> struct imx6_pcie *imx6_pcie = dev_get_drvdata(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);
>
> return 0;
> }
> @@ -959,10 +976,17 @@ static int imx6_pcie_probe(struct platform_device *pdev)
> break;
> default:
> 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");
> if (IS_ERR(imx6_pcie->iomuxc_gpr)) {
> dev_err(dev, "unable to find iomuxc registers\n");
> --
> 2.17.1
>

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