[PATCH v6 09/10] PCI: dw-rockchip: Add system PM support

[Sebastian Reichel <sebastian.reichel@collabora.com>]

Add system PM support for Rockchip PCIe Designware Controllers.

I've tested this on the Rockchip RK3576 EVB1, the Radxa ROCK 4D
and the ArmSom Sige5 boards.

While I haven't experienced any issues, most of my tests have been done
without any devices attached (i.e. default board without any extras), so
there _might_ still be some problems. As system suspend does not work at
all right now, I think it makes sense to get at least the basic
configurations working as soon as possible as it will allow us to catch
regressions by enabling system suspend in CI systems like KernelCI.

Co-developed-by: Shawn Lin <shawn.lin@rock-chips.com>
Signed-off-by: Shawn Lin <shawn.lin@rock-chips.com>
Signed-off-by: Sebastian Reichel <sebastian.reichel@collabora.com>
---
 drivers/pci/controller/dwc/pcie-dw-rockchip.c | 100 ++++++++++++++++++++++++++
 1 file changed, 100 insertions(+)

diff --git a/drivers/pci/controller/dwc/pcie-dw-rockchip.c b/drivers/pci/controller/dwc/pcie-dw-rockchip.c
index 47d9cab909bc..e675918ba184 100644
--- a/drivers/pci/controller/dwc/pcie-dw-rockchip.c
+++ b/drivers/pci/controller/dwc/pcie-dw-rockchip.c
@@ -120,6 +120,7 @@ struct rockchip_pcie {
 	struct gpio_desc *rst_gpio;
 	struct regulator *vpcie3v3;
 	struct irq_domain *irq_domain;
+	u32 intx;
 	const struct rockchip_pcie_of_data *data;
 	bool supports_clkreq;
 	struct delayed_work trace_work;
@@ -1042,6 +1043,99 @@ static int rockchip_pcie_rc_reset_root_port(struct pci_host_bridge *bridge,
 	return ret;
 }
 
+static int rockchip_pcie_suspend(struct device *dev)
+{
+	struct rockchip_pcie *rockchip = dev_get_drvdata(dev);
+	struct dw_pcie *pci = &rockchip->pci;
+	int ret;
+
+	if (rockchip->data->mode == DW_PCIE_EP_TYPE) {
+		dev_err(dev, "suspend is not supported in EP mode\n");
+		return -EOPNOTSUPP;
+	}
+
+	rockchip->intx = rockchip_pcie_readl_apb(rockchip, PCIE_CLIENT_INTR_MASK_LEGACY);
+
+	ret = dw_pcie_suspend_noirq(pci);
+	if (ret)
+		return ret;
+
+	gpiod_set_value_cansleep(rockchip->rst_gpio, 0);
+	rockchip_pcie_phy_deinit(rockchip);
+	clk_bulk_disable_unprepare(rockchip->clk_cnt, rockchip->clks);
+	reset_control_assert(rockchip->rst);
+	if (rockchip->vpcie3v3)
+		regulator_disable(rockchip->vpcie3v3);
+
+	return 0;
+}
+
+static int rockchip_pcie_resume(struct device *dev)
+{
+	struct rockchip_pcie *rockchip = dev_get_drvdata(dev);
+	struct dw_pcie *pci = &rockchip->pci;
+	int ret;
+
+	if (rockchip->data->mode == DW_PCIE_EP_TYPE) {
+		dev_err(dev, "resume is not supported in EP mode\n");
+		return -EOPNOTSUPP;
+	}
+
+	ret = clk_bulk_prepare_enable(rockchip->clk_cnt, rockchip->clks);
+	if (ret) {
+		dev_err(dev, "clock init failed: %d\n", ret);
+		return ret;
+	}
+
+	if (rockchip->vpcie3v3) {
+		ret = regulator_enable(rockchip->vpcie3v3);
+		if (ret)
+			goto err_disable_clk;
+	}
+
+	ret = rockchip_pcie_phy_init(rockchip);
+	if (ret) {
+		dev_err(dev, "phy init failed: %d\n", ret);
+		goto err_disable_regulator;
+	}
+
+	reset_control_deassert(rockchip->rst);
+
+	rockchip_pcie_writel_apb(rockchip, FIELD_PREP_WM16(0xffff, rockchip->intx),
+				 PCIE_CLIENT_INTR_MASK_LEGACY);
+
+	rockchip_pcie_enable_enhanced_ltssm_control_mode(rockchip, 0);
+	rockchip_pcie_set_controller_mode(rockchip, PCIE_CLIENT_MODE_RC);
+	rockchip_pcie_unmask_dll_indicator(rockchip);
+
+	gpiod_set_value_cansleep(rockchip->rst_gpio, 1);
+
+	ret = dw_pcie_resume_noirq(pci);
+	if (ret) {
+		dev_err(dev, "failed to resume: %d\n", ret);
+		/*
+		 * During resume, dw_pcie_wait_for_link() is called and when
+		 * there is no device connected at all it returns -EIO with
+		 * the message "Device found, but not active". Ignore it for
+		 * now.
+		 */
+		if (ret != -EIO)
+			goto err_deinit_phy;
+	}
+
+	return 0;
+
+err_deinit_phy:
+	gpiod_set_value_cansleep(rockchip->rst_gpio, 0);
+	rockchip_pcie_phy_deinit(rockchip);
+err_disable_regulator:
+	if (rockchip->vpcie3v3)
+		regulator_disable(rockchip->vpcie3v3);
+err_disable_clk:
+	clk_bulk_disable_unprepare(rockchip->clk_cnt, rockchip->clks);
+	return ret;
+}
+
 static const struct rockchip_pcie_of_data rockchip_pcie_rc_of_data_rk3568 = {
 	.mode = DW_PCIE_RC_TYPE,
 };
@@ -1072,11 +1166,17 @@ static const struct of_device_id rockchip_pcie_of_match[] = {
 	{},
 };
 
+static const struct dev_pm_ops rockchip_pcie_pm_ops = {
+	NOIRQ_SYSTEM_SLEEP_PM_OPS(rockchip_pcie_suspend,
+				  rockchip_pcie_resume)
+};
+
 static struct platform_driver rockchip_pcie_driver = {
 	.driver = {
 		.name	= "rockchip-dw-pcie",
 		.of_match_table = rockchip_pcie_of_match,
 		.suppress_bind_attrs = true,
+		.pm = &rockchip_pcie_pm_ops,
 	},
 	.probe = rockchip_pcie_probe,
 };

-- 
2.53.0