From f4e833ba2a955bc15c1ccaa5b0b3c2a0d7989bca Mon Sep 17 00:00:00 2001 From: Leonard Crestez Date: Thu, 19 Jul 2018 17:02:10 +0300 Subject: [PATCH] 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: Leonard Crestez [lorenzo.pieralisi@arm.com: updated commit log] Signed-off-by: Lorenzo Pieralisi Reviewed-by: Lucas Stach --- 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 d13dae5..2cbef2d 100644 --- a/drivers/pci/controller/dwc/pci-imx6.c +++ b/drivers/pci/controller/dwc/pci-imx6.c @@ -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"); -- 2.7.4