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Subject[PATCH 2/2] PCI: imx: Initial imx7d pm support
Date
On imx7d the phy is turned off in suspend and must be reset on resume.
Right now lspci -v fails after a suspend/resume cycle, fix this by
adding minimal suspend/resume code from the nxp vendor tree.

This is currently only enabled for imx7 but the same sequence can be
applied to other imx pcie variants.

Tested on imx7d-sabresd with an Intel 5622ANHMW wireless pcie adapter.

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

Signed-off-by: Leonard Crestez <leonard.crestez@nxp.com>
---
drivers/pci/dwc/pci-imx6.c | 94 ++++++++++++++++++++++++++++++++++++--
1 file changed, 89 insertions(+), 5 deletions(-)

diff --git a/drivers/pci/dwc/pci-imx6.c b/drivers/pci/dwc/pci-imx6.c
index 4818ef875f8a..ff6077eeb387 100644
--- a/drivers/pci/dwc/pci-imx6.c
+++ b/drivers/pci/dwc/pci-imx6.c
@@ -540,10 +540,27 @@ 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);
+ }
+}
+
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 +575,11 @@ 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;

@@ -681,10 +694,80 @@ 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 int imx6_pcie_suspend_noirq(struct device *dev)
+{
+ struct imx6_pcie *imx6_pcie = dev_get_drvdata(dev);
+
+ if (imx6_pcie->variant == IMX7D) {
+ /* Disable clks */
+ clk_disable_unprepare(imx6_pcie->pcie);
+ clk_disable_unprepare(imx6_pcie->pcie_phy);
+ clk_disable_unprepare(imx6_pcie->pcie_bus);
+ /* turn off external osc input */
+ regmap_update_bits(imx6_pcie->iomuxc_gpr, IOMUXC_GPR12,
+ IMX7D_GPR12_PCIE_PHY_REFCLK_SEL,
+ IMX7D_GPR12_PCIE_PHY_REFCLK_SEL);
+ }
+
+ return 0;
+}
+
+static void imx6_pcie_ltssm_disable(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, 0);
+ break;
+ case IMX7D:
+ reset_control_assert(imx6_pcie->apps_reset);
+ break;
+ }
+}
+
+static int imx6_pcie_resume_noirq(struct device *dev)
+{
+ int ret = 0;
+ struct imx6_pcie *imx6_pcie = dev_get_drvdata(dev);
+ struct pcie_port *pp = &imx6_pcie->pci->pp;
+
+ if (imx6_pcie->variant == IMX7D) {
+ imx6_pcie_ltssm_disable(dev);
+
+ imx6_pcie_assert_core_reset(imx6_pcie);
+ imx6_pcie_init_phy(imx6_pcie);
+ imx6_pcie_deassert_core_reset(imx6_pcie);
+
+ /*
+ * controller maybe turn off, re-configure again
+ */
+ dw_pcie_setup_rc(pp);
+
+ imx6_pcie_ltssm_enable(dev);
+
+ ret = imx6_pcie_wait_for_link(imx6_pcie);
+ if (ret < 0)
+ pr_info("pcie link is down after resume.\n");
+ }
+
+ return 0;
+}
+
+static const struct dev_pm_ops imx6_pcie_pm_ops = {
+ SET_NOIRQ_SYSTEM_SLEEP_PM_OPS(imx6_pcie_suspend_noirq,
+ imx6_pcie_resume_noirq)
+};
+#endif
+
static int imx6_pcie_probe(struct platform_device *pdev)
{
struct device *dev = &pdev->dev;
struct dw_pcie *pci;
struct imx6_pcie *imx6_pcie;
@@ -847,10 +930,11 @@ 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,
};

--
2.17.0
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