[PATCH v2 1/1] PCI: layerscape: Add power management support

[Frank Li]

From: Hou Zhiqiang <Zhiqiang.Hou@xxxxxxx>

Add PME_Turn_Off/PME_TO_Ack handshake sequence to PCIe devices, such as
NVME or wifi module, and finally put the PCIe controller into D3 state
after the L2/L3 ready state transition process completion.

However, it's important to note that not all devices may be able to
tolerate the PME_Turn_Off command. In general, fixed PCIe devices
connected to Layerscape, such as NXP wifi devices, are able to handle
this command.

Signed-off-by: Hou Zhiqiang <Zhiqiang.Hou@xxxxxxx>
Signed-off-by: Frank Li <Frank.Li@xxxxxxx>
---
Change from v1 to v2
- fixed Bjorn Helgaas's comments
- remove ls1043 and ls1021, which PME is not self cleaned. After check
spec, there are PME interrupt to indicate PEM_TO_ACK command. but I
have not these platform to debug it.  I just can test ls1028 platform
now. 

 drivers/pci/controller/dwc/pci-layerscape.c  | 219 ++++++++++++++++++-
 drivers/pci/controller/dwc/pcie-designware.h |   1 +
 2 files changed, 211 insertions(+), 9 deletions(-)

diff --git a/drivers/pci/controller/dwc/pci-layerscape.c b/drivers/pci/controller/dwc/pci-layerscape.c
index ed5fb492fe08..5fbc9151ff82 100644
--- a/drivers/pci/controller/dwc/pci-layerscape.c
+++ b/drivers/pci/controller/dwc/pci-layerscape.c
@@ -8,9 +8,11 @@
  * Author: Minghuan Lian <Minghuan.Lian@xxxxxxxxxxxxx>
  */
 
+#include <linux/delay.h>
 #include <linux/kernel.h>
 #include <linux/interrupt.h>
 #include <linux/init.h>
+#include <linux/iopoll.h>
 #include <linux/of_pci.h>
 #include <linux/of_platform.h>
 #include <linux/of_address.h>
@@ -29,10 +31,40 @@
 
 #define PCIE_IATU_NUM		6
 
+/* PF Message Command Register */
+#define LS_PCIE_PF_MCR		0x2c
+#define PF_MCR_PTOMR		BIT(0)
+#define PF_MCR_EXL2S		BIT(1)
+
+#define LS_PCIE_IS_L2(v)	\
+	(((v) & PORT_LOGIC_LTSSM_STATE_MASK) == PORT_LOGIC_LTSSM_STATE_L2)
+
+struct ls_pcie;
+
+struct ls_pcie_host_pm_ops {
+	int (*pm_init)(struct ls_pcie *pcie);
+	void (*send_turn_off_message)(struct ls_pcie *pcie);
+	void (*exit_from_l2)(struct ls_pcie *pcie);
+};
+
+struct ls_pcie_drvdata {
+	const u32 pf_off;
+	const u32 lut_off;
+	const struct ls_pcie_host_pm_ops *pm_ops;
+};
+
 struct ls_pcie {
 	struct dw_pcie *pci;
+	const struct ls_pcie_drvdata *drvdata;
+	void __iomem *pf_base;
+	void __iomem *lut_base;
+	bool big_endian;
+	bool pm_support;
+	struct regmap *scfg;
+	int index;
 };
 
+#define ls_pcie_pf_readl_addr(addr)	ls_pcie_pf_readl(pcie, addr)
 #define to_ls_pcie(x)	dev_get_drvdata((x)->dev)
 
 static bool ls_pcie_is_bridge(struct ls_pcie *pcie)
@@ -73,6 +105,69 @@ static void ls_pcie_fix_error_response(struct ls_pcie *pcie)
 	iowrite32(PCIE_ABSERR_SETTING, pci->dbi_base + PCIE_ABSERR);
 }
 
+static u32 ls_pcie_pf_readl(struct ls_pcie *pcie, u32 off)
+{
+	if (pcie->big_endian)
+		return ioread32be(pcie->pf_base + off);
+
+	return ioread32(pcie->pf_base + off);
+}
+
+static void ls_pcie_pf_writel(struct ls_pcie *pcie, u32 off, u32 val)
+{
+	if (pcie->big_endian)
+		return iowrite32be(val, pcie->pf_base + off);
+
+	return iowrite32(val, pcie->pf_base + off);
+}
+
+static void ls_pcie_send_turnoff_msg(struct ls_pcie *pcie)
+{
+	u32 val;
+	int ret;
+
+	val = ls_pcie_pf_readl(pcie, LS_PCIE_PF_MCR);
+	val |= PF_MCR_PTOMR;
+	ls_pcie_pf_writel(pcie, LS_PCIE_PF_MCR, val);
+
+	ret = readx_poll_timeout(ls_pcie_pf_readl_addr, LS_PCIE_PF_MCR,
+				 val, !(val & PF_MCR_PTOMR), 100, 10000);
+	if (ret)
+		dev_warn(pcie->pci->dev, "poll turn off message timeout\n");
+}
+
+static void ls_pcie_exit_from_l2(struct ls_pcie *pcie)
+{
+	u32 val;
+	int ret;
+
+	val = ls_pcie_pf_readl(pcie, LS_PCIE_PF_MCR);
+	val |= PF_MCR_EXL2S;
+	ls_pcie_pf_writel(pcie, LS_PCIE_PF_MCR, val);
+
+	ret = readx_poll_timeout(ls_pcie_pf_readl_addr, LS_PCIE_PF_MCR,
+				 val, !(val & PF_MCR_EXL2S), 100, 10000);
+	if (ret)
+		dev_warn(pcie->pci->dev, "poll exit L2 state timeout\n");
+}
+
+static int ls_pcie_pm_init(struct ls_pcie *pcie)
+{
+	return 0;
+}
+
+static void ls_pcie_set_dstate(struct ls_pcie *pcie, u32 dstate)
+{
+	struct dw_pcie *pci = pcie->pci;
+	u8 offset = dw_pcie_find_capability(pci, PCI_CAP_ID_PM);
+	u32 val;
+
+	val = dw_pcie_readw_dbi(pci, offset + PCI_PM_CTRL);
+	val &= ~PCI_PM_CTRL_STATE_MASK;
+	val |= dstate;
+	dw_pcie_writew_dbi(pci, offset + PCI_PM_CTRL, val);
+}
+
 static int ls_pcie_host_init(struct dw_pcie_rp *pp)
 {
 	struct dw_pcie *pci = to_dw_pcie_from_pp(pp);
@@ -86,23 +181,46 @@ static int ls_pcie_host_init(struct dw_pcie_rp *pp)
 
 	ls_pcie_drop_msg_tlp(pcie);
 
+	if (pcie->drvdata->pm_ops && pcie->drvdata->pm_ops->pm_init &&
+	    !pcie->drvdata->pm_ops->pm_init(pcie))
+		pcie->pm_support = true;
+
 	return 0;
 }
 
+static struct ls_pcie_host_pm_ops ls_pcie_host_pm_ops = {
+	.pm_init = &ls_pcie_pm_init,
+	.send_turn_off_message = &ls_pcie_send_turnoff_msg,
+	.exit_from_l2 = &ls_pcie_exit_from_l2,
+};
+
 static const struct dw_pcie_host_ops ls_pcie_host_ops = {
 	.host_init = ls_pcie_host_init,
 };
 
+static const struct ls_pcie_drvdata ls1021a_drvdata = {
+};
+
+static const struct ls_pcie_drvdata ls1043a_drvdata = {
+	.lut_off = 0x10000,
+};
+
+static const struct ls_pcie_drvdata layerscape_drvdata = {
+	.lut_off = 0x80000,
+	.pf_off = 0xc0000,
+	.pm_ops = &ls_pcie_host_pm_ops,
+};
+
 static const struct of_device_id ls_pcie_of_match[] = {
-	{ .compatible = "fsl,ls1012a-pcie", },
-	{ .compatible = "fsl,ls1021a-pcie", },
-	{ .compatible = "fsl,ls1028a-pcie", },
-	{ .compatible = "fsl,ls1043a-pcie", },
-	{ .compatible = "fsl,ls1046a-pcie", },
-	{ .compatible = "fsl,ls2080a-pcie", },
-	{ .compatible = "fsl,ls2085a-pcie", },
-	{ .compatible = "fsl,ls2088a-pcie", },
-	{ .compatible = "fsl,ls1088a-pcie", },
+	{ .compatible = "fsl,ls1012a-pcie", .data = &layerscape_drvdata },
+	{ .compatible = "fsl,ls1021a-pcie", .data = &ls1021a_drvdata },
+	{ .compatible = "fsl,ls1028a-pcie", .data = &layerscape_drvdata },
+	{ .compatible = "fsl,ls1043a-pcie", .data = &ls1043a_drvdata },
+	{ .compatible = "fsl,ls1046a-pcie", .data = &layerscape_drvdata },
+	{ .compatible = "fsl,ls2080a-pcie", .data = &layerscape_drvdata },
+	{ .compatible = "fsl,ls2085a-pcie", .data = &layerscape_drvdata },
+	{ .compatible = "fsl,ls2088a-pcie", .data = &layerscape_drvdata },
+	{ .compatible = "fsl,ls1088a-pcie", .data = &layerscape_drvdata },
 	{ },
 };
 
@@ -121,6 +239,8 @@ static int ls_pcie_probe(struct platform_device *pdev)
 	if (!pci)
 		return -ENOMEM;
 
+	pcie->drvdata = of_device_get_match_data(dev);
+
 	pci->dev = dev;
 	pci->pp.ops = &ls_pcie_host_ops;
 
@@ -131,6 +251,14 @@ static int ls_pcie_probe(struct platform_device *pdev)
 	if (IS_ERR(pci->dbi_base))
 		return PTR_ERR(pci->dbi_base);
 
+	pcie->big_endian = of_property_read_bool(dev->of_node, "big-endian");
+
+	if (pcie->drvdata->lut_off)
+		pcie->lut_base = pci->dbi_base + pcie->drvdata->lut_off;
+
+	if (pcie->drvdata->pf_off)
+		pcie->pf_base = pci->dbi_base + pcie->drvdata->pf_off;
+
 	if (!ls_pcie_is_bridge(pcie))
 		return -ENODEV;
 
@@ -139,12 +267,85 @@ static int ls_pcie_probe(struct platform_device *pdev)
 	return dw_pcie_host_init(&pci->pp);
 }
 
+static bool ls_pcie_pm_supported(struct ls_pcie *pcie)
+{
+	if (!dw_pcie_link_up(pcie->pci)) {
+		dev_dbg(pcie->pci->dev, "Endpoint isn't present\n");
+		return false;
+	}
+
+	return pcie->pm_support;
+}
+
+#ifdef CONFIG_PM_SLEEP
+static int ls_pcie_suspend_noirq(struct device *dev)
+{
+	struct ls_pcie *pcie = dev_get_drvdata(dev);
+	struct dw_pcie *pci = pcie->pci;
+	u32 val;
+	int ret;
+
+	if (!ls_pcie_pm_supported(pcie))
+		return 0;
+
+	pcie->drvdata->pm_ops->send_turn_off_message(pcie);
+
+	/* 10ms timeout to check L2 ready */
+	ret = readl_poll_timeout(pci->dbi_base + PCIE_PORT_DEBUG0,
+				 val, LS_PCIE_IS_L2(val), 100, 10000);
+	if (ret) {
+		dev_err(dev, "PCIe link enter L2 timeout! ltssm = 0x%x\n", val);
+		return ret;
+	}
+
+	ls_pcie_set_dstate(pcie, 0x3);
+
+	return 0;
+}
+
+static int ls_pcie_resume_noirq(struct device *dev)
+{
+	struct ls_pcie *pcie = dev_get_drvdata(dev);
+	struct dw_pcie *pci = pcie->pci;
+	int ret;
+
+	if (!ls_pcie_pm_supported(pcie))
+		return 0;
+
+	ls_pcie_set_dstate(pcie, 0x0);
+
+	pcie->drvdata->pm_ops->exit_from_l2(pcie);
+
+	ret = ls_pcie_host_init(&pci->pp);
+	if (ret) {
+		dev_err(dev, "PCIe host init failed! ret = 0x%x\n", ret);
+		return ret;
+	}
+
+	dw_pcie_setup_rc(&pci->pp);
+
+	ret = dw_pcie_wait_for_link(pci);
+	if (ret) {
+		dev_err(dev, "Wait link up timeout! ret = 0x%x\n", ret);
+		return ret;
+	}
+
+	return 0;
+}
+#endif /* CONFIG_PM_SLEEP */
+
+static const struct dev_pm_ops ls_pcie_pm_ops = {
+	SET_NOIRQ_SYSTEM_SLEEP_PM_OPS(ls_pcie_suspend_noirq,
+				      ls_pcie_resume_noirq)
+};
+
 static struct platform_driver ls_pcie_driver = {
 	.probe = ls_pcie_probe,
 	.driver = {
 		.name = "layerscape-pcie",
 		.of_match_table = ls_pcie_of_match,
 		.suppress_bind_attrs = true,
+		.pm = &ls_pcie_pm_ops,
 	},
 };
 builtin_platform_driver(ls_pcie_driver);
diff --git a/drivers/pci/controller/dwc/pcie-designware.h b/drivers/pci/controller/dwc/pcie-designware.h
index 79713ce075cc..7de8409e2433 100644
--- a/drivers/pci/controller/dwc/pcie-designware.h
+++ b/drivers/pci/controller/dwc/pcie-designware.h
@@ -94,6 +94,7 @@
 #define PCIE_PORT_DEBUG0		0x728
 #define PORT_LOGIC_LTSSM_STATE_MASK	0x1f
 #define PORT_LOGIC_LTSSM_STATE_L0	0x11
+#define PORT_LOGIC_LTSSM_STATE_L2	0x15
 #define PCIE_PORT_DEBUG1		0x72C
 #define PCIE_PORT_DEBUG1_LINK_UP		BIT(4)
 #define PCIE_PORT_DEBUG1_LINK_IN_TRAINING	BIT(29)
-- 
2.34.1