PCI: layerscape: Add power management support for ls1028a

Add PME_Turn_off/PME_TO_Ack handshake sequence for ls1028a platform.

Implemented on top of common dwc dw_pcie_suspend(resume)_noirq()
functions to handle system enter/exit suspend states.

Link: https://lore.kernel.org/r/20230821184815.2167131-4-Frank.Li@nxp.com
Signed-off-by: Hou Zhiqiang <Zhiqiang.Hou@nxp.com>
Signed-off-by: Frank Li <Frank.Li@nxp.com>
Signed-off-by: Lorenzo Pieralisi <lpieralisi@kernel.org>
Acked-by: Manivannan Sadhasivam <mani@kernel.org>

drivers/pci/controller/dwc/pci-layerscape.c

@@ -8,9 +8,11 @@
  * Author: Minghuan Lian <Minghuan.Lian@freescale.com>
  */
 
+#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>
@@ -20,6 +22,7 @@
 #include <linux/mfd/syscon.h>
 #include <linux/regmap.h>
 
+#include "../../pci.h"
 #include "pcie-designware.h"
 
 /* PEX Internal Configuration Registers */
@@ -27,12 +30,26 @@
 #define PCIE_ABSERR		0x8d0 /* Bridge Slave Error Response Register */
 #define PCIE_ABSERR_SETTING	0x9401 /* Forward error of non-posted request */
 
+/* PF Message Command Register */
+#define LS_PCIE_PF_MCR		0x2c
+#define PF_MCR_PTOMR		BIT(0)
+#define PF_MCR_EXL2S		BIT(1)
+
 #define PCIE_IATU_NUM		6
 
+struct ls_pcie_drvdata {
+	const u32 pf_off;
+	bool pm_support;
+};
+
 struct ls_pcie {
 	struct dw_pcie *pci;
+	const struct ls_pcie_drvdata *drvdata;
+	void __iomem *pf_base;
+	bool big_endian;
 };
 
+#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 +90,68 @@ 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)
+		iowrite32be(val, pcie->pf_base + off);
+	else
+		iowrite32(val, pcie->pf_base + off);
+}
+
+static void ls_pcie_send_turnoff_msg(struct dw_pcie_rp *pp)
+{
+	struct dw_pcie *pci = to_dw_pcie_from_pp(pp);
+	struct ls_pcie *pcie = to_ls_pcie(pci);
+	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),
+				 PCIE_PME_TO_L2_TIMEOUT_US/10,
+				 PCIE_PME_TO_L2_TIMEOUT_US);
+	if (ret)
+		dev_err(pcie->pci->dev, "PME_Turn_off timeout\n");
+}
+
+static void ls_pcie_exit_from_l2(struct dw_pcie_rp *pp)
+{
+	struct dw_pcie *pci = to_dw_pcie_from_pp(pp);
+	struct ls_pcie *pcie = to_ls_pcie(pci);
+	u32 val;
+	int ret;
+
+	/*
+	 * Set PF_MCR_EXL2S bit in LS_PCIE_PF_MCR register for the link
+	 * to exit L2 state.
+	 */
+	val = ls_pcie_pf_readl(pcie, LS_PCIE_PF_MCR);
+	val |= PF_MCR_EXL2S;
+	ls_pcie_pf_writel(pcie, LS_PCIE_PF_MCR, val);
+
+	/*
+	 * L2 exit timeout of 10ms is not defined in the specifications,
+	 * it was chosen based on empirical observations.
+	 */
+	ret = readx_poll_timeout(ls_pcie_pf_readl_addr, LS_PCIE_PF_MCR,
+				 val, !(val & PF_MCR_EXL2S),
+				 1000,
+				 10000);
+	if (ret)
+		dev_err(pcie->pci->dev, "L2 exit timeout\n");
+}
+
 static int ls_pcie_host_init(struct dw_pcie_rp *pp)
 {
 	struct dw_pcie *pci = to_dw_pcie_from_pp(pp);
@@ -91,18 +170,28 @@ static int ls_pcie_host_init(struct dw_pcie_rp *pp)
 
 static const struct dw_pcie_host_ops ls_pcie_host_ops = {
 	.host_init = ls_pcie_host_init,
+	.pme_turn_off = ls_pcie_send_turnoff_msg,
+};
+
+static const struct ls_pcie_drvdata ls1021a_drvdata = {
+	.pm_support = false,
+};
+
+static const struct ls_pcie_drvdata layerscape_drvdata = {
+	.pf_off = 0xc0000,
+	.pm_support = true,
 };
 
 static const struct of_device_id ls_pcie_of_match[] = {
-	{ .compatible = "fsl,ls1012a-pcie", },
+	{ .compatible = "fsl,ls1012a-pcie", .data = &layerscape_drvdata },
-	{ .compatible = "fsl,ls1021a-pcie", },
+	{ .compatible = "fsl,ls1021a-pcie", .data = &ls1021a_drvdata },
-	{ .compatible = "fsl,ls1028a-pcie", },
+	{ .compatible = "fsl,ls1028a-pcie", .data = &layerscape_drvdata },
-	{ .compatible = "fsl,ls1043a-pcie", },
+	{ .compatible = "fsl,ls1043a-pcie", .data = &ls1021a_drvdata },
-	{ .compatible = "fsl,ls1046a-pcie", },
+	{ .compatible = "fsl,ls1046a-pcie", .data = &layerscape_drvdata },
-	{ .compatible = "fsl,ls2080a-pcie", },
+	{ .compatible = "fsl,ls2080a-pcie", .data = &layerscape_drvdata },
-	{ .compatible = "fsl,ls2085a-pcie", },
+	{ .compatible = "fsl,ls2085a-pcie", .data = &layerscape_drvdata },
-	{ .compatible = "fsl,ls2088a-pcie", },
+	{ .compatible = "fsl,ls2088a-pcie", .data = &layerscape_drvdata },
-	{ .compatible = "fsl,ls1088a-pcie", },
+	{ .compatible = "fsl,ls1088a-pcie", .data = &layerscape_drvdata },
 	{ },
 };
 
@@ -121,6 +210,8 @@ 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 +222,10 @@ 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");
+
+	pcie->pf_base = pci->dbi_base + pcie->drvdata->pf_off;
+
 	if (!ls_pcie_is_bridge(pcie))
 		return -ENODEV;
 
@@ -139,12 +234,39 @@ static int ls_pcie_probe(struct platform_device *pdev)
 	return dw_pcie_host_init(&pci->pp);
 }
 
+static int ls_pcie_suspend_noirq(struct device *dev)
+{
+	struct ls_pcie *pcie = dev_get_drvdata(dev);
+
+	if (!pcie->drvdata->pm_support)
+		return 0;
+
+	return dw_pcie_suspend_noirq(pcie->pci);
+}
+
+static int ls_pcie_resume_noirq(struct device *dev)
+{
+	struct ls_pcie *pcie = dev_get_drvdata(dev);
+
+	if (!pcie->drvdata->pm_support)
+		return 0;
+
+	ls_pcie_exit_from_l2(&pcie->pci->pp);
+
+	return dw_pcie_resume_noirq(pcie->pci);
+}
+
+static const struct dev_pm_ops ls_pcie_pm_ops = {
+	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);