Date:   Wed, 22 Dec 2021 21:37:42 +0530
From:   Prasad Malisetty <quic_c_pmaliset@...cinc.com>
To:     agross@...nel.org, bjorn.andersson@...aro.org,
        lorenzo.pieralisi@....com, robh@...nel.org, kw@...ux.com,
        bhelgaas@...gle.com, linux-pci@...r.kernel.org,
        linux-arm-msm@...r.kernel.org, linux-kernel@...r.kernel.org
Cc:     quic_vbadigan@...cinc.com, quic_ramkri@...cinc.com,
        manivannan.sadhasivam@...aro.org, swboyd@...omium.org,
        Prasad Malisetty <quic_pmaliset@...cinc.com>
Subject: [PATCH v1] PCI: qcom: Add system PM support

From: Prasad Malisetty <quic_pmaliset@...cinc.com>

Add suspend_noirq and resume_noirq callbacks to handle
System suspend and resume in dwc pcie controller driver.

When system suspends, send PME turnoff message to enter
link into L2 state. Along with powerdown the PHY, disable
pipe clock, switch gcc_pcie_1_pipe_clk_src to XO if mux is
supported and disable the pcie clocks, regulators.

When system resumes, PCIe link will be re-established and
setup rc settings.

Signed-off-by: Prasad Malisetty <quic_pmaliset@...cinc.com>
---
 drivers/pci/controller/dwc/pcie-qcom.c | 103 +++++++++++++++++++++++++++++++++
 1 file changed, 103 insertions(+)

diff --git a/drivers/pci/controller/dwc/pcie-qcom.c b/drivers/pci/controller/dwc/pcie-qcom.c
index c19cd506..24dcf5a 100644
--- a/drivers/pci/controller/dwc/pcie-qcom.c
+++ b/drivers/pci/controller/dwc/pcie-qcom.c
@@ -73,6 +73,8 @@
 
 #define PCIE20_PARF_Q2A_FLUSH			0x1AC
 
+#define PCIE20_PARF_PM_STTS                     0x24
+
 #define PCIE20_MISC_CONTROL_1_REG		0x8BC
 #define DBI_RO_WR_EN				1
 
@@ -1616,6 +1618,107 @@ static int qcom_pcie_probe(struct platform_device *pdev)
 	return ret;
 }
 
+static int qcom_pcie_send_pme_turnoff_msg(struct qcom_pcie *pcie)
+{
+	int ret = 0;
+	u32 val = 0, poll_val = 0;
+	uint64_t l23_rdy_poll_timeout = 100000;
+	struct dw_pcie *pci = pcie->pci;
+	struct device *dev = pci->dev;
+
+	val = readl(pcie->elbi + PCIE20_ELBI_SYS_CTRL);
+	val |= BIT(4);
+	writel(val, pcie->elbi + PCIE20_ELBI_SYS_CTRL);
+
+	ret = readl_poll_timeout((pcie->parf + PCIE20_PARF_PM_STTS), poll_val,
+			(poll_val & BIT(5)), 10000, l23_rdy_poll_timeout);
+	if (!ret)
+		dev_dbg(dev, "PCIe: PM_Enter_L23 is received\n");
+	else
+		dev_err(dev, "PM_Enter_L23 is NOT received.PARF_PM_STTS 0x%x\n",
+			readl_relaxed(pcie->parf + PCIE20_PARF_PM_STTS));
+
+	return ret;
+}
+
+static void qcom_pcie_host_disable(struct qcom_pcie *pcie)
+{
+	struct qcom_pcie_resources_2_7_0 *res = &pcie->res.v2_7_0;
+
+	/*Assert the reset of endpoint */
+	qcom_ep_reset_assert(pcie);
+
+	/* Put PHY into POWER DOWN state */
+	phy_power_off(pcie->phy);
+
+	writel(1, pcie->parf + PCIE20_PARF_PHY_CTRL);
+
+	/* Disable pipe clock */
+	pcie->ops->post_deinit(pcie);
+
+	/* Change GCC_PCIE_1_PIPE_MUXR register to 0x2 for XO as parent */
+	if (pcie->pipe_clk_need_muxing)
+		clk_set_parent(res->pipe_clk_src, res->ref_clk_src);
+
+	/* Disable PCIe clocks and regulators*/
+	pcie->ops->deinit(pcie);
+}
+
+static int __maybe_unused qcom_pcie_pm_suspend_noirq(struct device *dev)
+{
+	int ret = 0;
+	struct qcom_pcie *pcie = dev_get_drvdata(dev);
+	struct dw_pcie *pci = pcie->pci;
+
+	if (!dw_pcie_link_up(pci)) {
+		dev_err(dev, "Power has been turned off already\n");
+		return ret;
+	}
+
+	/* Send PME turnoff msg */
+	ret = qcom_pcie_send_pme_turnoff_msg(pcie);
+	if (ret)
+		return ret;
+
+	/* Power down the PHY, disable clock and regulators */
+	qcom_pcie_host_disable(pcie);
+
+	dev_info(dev, "PM: PCI is suspended\n");
+	return ret;
+}
+
+/* Resume the PCIe link */
+static int __maybe_unused qcom_pcie_pm_resume_noirq(struct device *dev)
+{
+	int ret = 0;
+	struct qcom_pcie *pcie = dev_get_drvdata(dev);
+	struct dw_pcie *pci = pcie->pci;
+	struct pcie_port *pp = &pci->pp;
+
+	dev_info(dev, "PM: Resuming\n");
+
+	/* Initialize PCIe host */
+	ret = qcom_pcie_host_init(pp);
+	if (ret)
+		dev_err(dev, "cannot initialize host\n");
+
+	dw_pcie_iatu_detect(pci);
+	dw_pcie_setup_rc(pp);
+
+	/* Start the PCIe link */
+	qcom_pcie_start_link(pci);
+
+	ret = dw_pcie_wait_for_link(pci);
+	if (ret)
+		dev_err(dev, "Link never came up, Resume failed\n");
+
+	return ret;
+}
+
+static const struct dev_pm_ops qcom_pcie_pm_ops = {
+	SET_NOIRQ_SYSTEM_SLEEP_PM_OPS(qcom_pcie_pm_suspend_noirq, qcom_pcie_pm_resume_noirq)
+};
+
 static const struct of_device_id qcom_pcie_match[] = {
 	{ .compatible = "qcom,pcie-apq8084", .data = &apq8084_cfg },
 	{ .compatible = "qcom,pcie-ipq8064", .data = &ipq8064_cfg },
-- 
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