[RESEND] PCI: imx: Initial imx7d pm support

From: Leonard Crestez
Date: Mon Aug 27 2018 - 07:29:04 EST


On imx7d the pcie-phy power domain is turned off in suspend and this can
make the system hang after resume when attempting any read from PCI.

Fix this by adding minimal suspend/resume code from the nxp internal
tree. This will prepare for powering down on suspend and reset the block
on resume.

Code is only for imx7d but a very similar sequence can be used for
other socs.

The original author is mostly Richard Zhu <hongxing.zhu@xxxxxxx>, this
patch adjusts the code to the upstream imx7d implemention using reset
controls and power domains.

Signed-off-by: Leonard Crestez <leonard.crestez@xxxxxxx>
Reviewed-by: Lucas Stach <l.stach@xxxxxxxxxxxxxx>
---
drivers/pci/controller/dwc/pci-imx6.c | 97 +++++++++++++++++++++++++--
1 file changed, 92 insertions(+), 5 deletions(-)

Resending after RC1 as suggested here: https://lkml.org/lkml/2018/8/8/496

This was initially sent together with a dts fix, that was already
accepted by Shawn: https://lkml.org/lkml/2018/8/21/529

Some dependencies in this area are complicated but as far as I know
including this patch without others should not break anything that was
not already broken. Since this is a patch for something that has never
worked before it should be treated as a feature not a bugfix.

I have a few other patches for imx pci but it's better to deal with them
separately. This initial patch adding suspend support is useful by
itself.

diff --git a/drivers/pci/controller/dwc/pci-imx6.c b/drivers/pci/controller/dwc/pci-imx6.c
index 4a9a673b4777..65b6d1015723 100644
--- a/drivers/pci/controller/dwc/pci-imx6.c
+++ b/drivers/pci/controller/dwc/pci-imx6.c
@@ -540,10 +540,28 @@ static int imx6_pcie_wait_for_speed_change(struct imx6_pcie *imx6_pcie)

dev_err(dev, "Speed change timeout\n");
return -EINVAL;
}

+static void imx6_pcie_ltssm_enable(struct device *dev)
+{
+ struct imx6_pcie *imx6_pcie = dev_get_drvdata(dev);
+
+ switch (imx6_pcie->variant) {
+ case IMX6Q:
+ case IMX6SX:
+ case IMX6QP:
+ regmap_update_bits(imx6_pcie->iomuxc_gpr, IOMUXC_GPR12,
+ IMX6Q_GPR12_PCIE_CTL_2,
+ IMX6Q_GPR12_PCIE_CTL_2);
+ break;
+ case IMX7D:
+ reset_control_deassert(imx6_pcie->apps_reset);
+ break;
+ }
+}
+
static int imx6_pcie_establish_link(struct imx6_pcie *imx6_pcie)
{
struct dw_pcie *pci = imx6_pcie->pci;
struct device *dev = pci->dev;
u32 tmp;
@@ -558,15 +576,11 @@ static int imx6_pcie_establish_link(struct imx6_pcie *imx6_pcie)
tmp &= ~PCIE_RC_LCR_MAX_LINK_SPEEDS_MASK;
tmp |= PCIE_RC_LCR_MAX_LINK_SPEEDS_GEN1;
dw_pcie_writel_dbi(pci, PCIE_RC_LCR, tmp);

/* Start LTSSM. */
- if (imx6_pcie->variant == IMX7D)
- reset_control_deassert(imx6_pcie->apps_reset);
- else
- regmap_update_bits(imx6_pcie->iomuxc_gpr, IOMUXC_GPR12,
- IMX6Q_GPR12_PCIE_CTL_2, 1 << 10);
+ imx6_pcie_ltssm_enable(dev);

ret = imx6_pcie_wait_for_link(imx6_pcie);
if (ret)
goto err_reset_phy;

@@ -680,10 +694,82 @@ static int imx6_add_pcie_port(struct imx6_pcie *imx6_pcie,

static const struct dw_pcie_ops dw_pcie_ops = {
.link_up = imx6_pcie_link_up,
};

+#ifdef CONFIG_PM_SLEEP
+static void imx6_pcie_ltssm_disable(struct device *dev)
+{
+ struct imx6_pcie *imx6_pcie = dev_get_drvdata(dev);
+
+ switch (imx6_pcie->variant) {
+ case IMX6SX:
+ case IMX6QP:
+ regmap_update_bits(imx6_pcie->iomuxc_gpr, IOMUXC_GPR12,
+ IMX6Q_GPR12_PCIE_CTL_2, 0);
+ break;
+ case IMX7D:
+ reset_control_assert(imx6_pcie->apps_reset);
+ break;
+ default:
+ dev_err(dev, "ltssm_disable not supported\n");
+ }
+}
+
+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);
+
+ if (imx6_pcie->variant == IMX7D) {
+ regmap_update_bits(imx6_pcie->iomuxc_gpr, IOMUXC_GPR12,
+ IMX7D_GPR12_PCIE_PHY_REFCLK_SEL,
+ IMX7D_GPR12_PCIE_PHY_REFCLK_SEL);
+ }
+}
+
+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_clk_disable(imx6_pcie);
+ imx6_pcie_ltssm_disable(dev);
+
+ return 0;
+}
+
+static int imx6_pcie_resume_noirq(struct device *dev)
+{
+ int ret;
+ struct imx6_pcie *imx6_pcie = dev_get_drvdata(dev);
+ struct pcie_port *pp = &imx6_pcie->pci->pp;
+
+ if (imx6_pcie->variant != IMX7D)
+ return 0;
+
+ imx6_pcie_assert_core_reset(imx6_pcie);
+ imx6_pcie_init_phy(imx6_pcie);
+ imx6_pcie_deassert_core_reset(imx6_pcie);
+ dw_pcie_setup_rc(pp);
+
+ ret = imx6_pcie_establish_link(imx6_pcie);
+ if (ret < 0)
+ dev_info(dev, "pcie link is down after resume.\n");
+
+ return 0;
+}
+#endif
+
+static const struct dev_pm_ops imx6_pcie_pm_ops = {
+ SET_NOIRQ_SYSTEM_SLEEP_PM_OPS(imx6_pcie_suspend_noirq,
+ imx6_pcie_resume_noirq)
+};
+
static int imx6_pcie_probe(struct platform_device *pdev)
{
struct device *dev = &pdev->dev;
struct dw_pcie *pci;
struct imx6_pcie *imx6_pcie;
@@ -846,10 +932,11 @@ static const struct of_device_id imx6_pcie_of_match[] = {
static struct platform_driver imx6_pcie_driver = {
.driver = {
.name = "imx6q-pcie",
.of_match_table = imx6_pcie_of_match,
.suppress_bind_attrs = true,
+ .pm = &imx6_pcie_pm_ops,
},
.probe = imx6_pcie_probe,
.shutdown = imx6_pcie_shutdown,
};

--
2.17.1