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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: Leonard Crestez <leonard.crestez@nxp.com>
[lorenzo.pieralisi@arm.com: updated commit log]
Signed-off-by: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
Reviewed-by: Lucas Stach <l.stach@pengutronix.de>
This commit is contained in:
Leonard Crestez 2018-07-19 17:02:10 +03:00 committed by Lorenzo Pieralisi
parent 3aedf7e135
commit f4e833ba2a
1 changed files with 24 additions and 0 deletions
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24
drivers/pci/controller/dwc/pci-imx6.c
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@ -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");