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.
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.cres...@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
