[PATCH v2 3/3] PCI: rockchip: Add system PM support

[Shawn Lin <shawn.lin@rock-chips.com>]

This patch adds system PM support for Rockchip's RC.
For pre S3, the EP is configured into D3 state which guarantees
the link state should be in L1. So we could send PME_Turn_Off message
to the EP and wait for its ACK to make the link state into L2 or L3
without the aux-supply. This could help save more power which I think
should be very important for mobile devices.

Signed-off-by: Shawn Lin <shawn.lin@rock-chips.com>

---

Changes in v2:
- Wrap the 'x' in parentheses
- add msg regison mapped support
- enable int for err case in suspend_noirq

 drivers/pci/host/pcie-rockchip.c | 102 +++++++++++++++++++++++++++++++++++++++
 1 file changed, 102 insertions(+)

diff --git a/drivers/pci/host/pcie-rockchip.c b/drivers/pci/host/pcie-rockchip.c
index 457401d..f2828a8 100644
--- a/drivers/pci/host/pcie-rockchip.c
+++ b/drivers/pci/host/pcie-rockchip.c
@@ -20,6 +20,7 @@
 #include <linux/gpio/consumer.h>
 #include <linux/init.h>
 #include <linux/interrupt.h>
+#include <linux/iopoll.h>
 #include <linux/irq.h>
 #include <linux/irqchip/chained_irq.h>
 #include <linux/irqdomain.h>
@@ -55,6 +56,10 @@
 #define   PCIE_CLIENT_MODE_RC		  HIWORD_UPDATE_BIT(0x0040)
 #define   PCIE_CLIENT_GEN_SEL_1		  HIWORD_UPDATE(0x0080, 0)
 #define   PCIE_CLIENT_GEN_SEL_2		  HIWORD_UPDATE_BIT(0x0080)
+#define PCIE_CLIENT_DEBUG_OUT_0		(PCIE_CLIENT_BASE + 0x3c)
+#define   PCIE_CLIENT_DEBUG_LTSSM_MASK		GENMASK(5, 0)
+#define   PCIE_CLIENT_DEBUG_LTSSM_L1		0x18
+#define   PCIE_CLIENT_DEBUG_LTSSM_L2		0x19
 #define PCIE_CLIENT_BASIC_STATUS1	(PCIE_CLIENT_BASE + 0x48)
 #define   PCIE_CLIENT_LINK_STATUS_UP		0x00300000
 #define   PCIE_CLIENT_LINK_STATUS_MASK		0x00300000
@@ -169,9 +174,11 @@
 #define IB_ROOT_PORT_REG_SIZE_SHIFT		3
 #define AXI_WRAPPER_IO_WRITE			0x6
 #define AXI_WRAPPER_MEM_WRITE			0x2
+#define AXI_WRAPPER_NOR_MSG			0xc
 
 #define MAX_AXI_IB_ROOTPORT_REGION_NUM		3
 #define MIN_AXI_ADDR_BITS_PASSED		8
+#define PCIE_RC_SEND_PME_OFF			0x11960
 #define ROCKCHIP_VENDOR_ID			0x1d87
 #define PCIE_ECAM_BUS(x)			(((x) & 0xff) << 20)
 #define PCIE_ECAM_DEV(x)			(((x) & 0x1f) << 15)
@@ -180,6 +187,9 @@
 #define PCIE_ECAM_ADDR(bus, dev, func, reg) \
 	  (PCIE_ECAM_BUS(bus) | PCIE_ECAM_DEV(dev) | \
 	   PCIE_ECAM_FUNC(func) | PCIE_ECAM_REG(reg))
+#define PCIE_LINK_IS_L2(x) \
+		(((x) & PCIE_CLIENT_DEBUG_LTSSM_MASK) == \
+		 PCIE_CLIENT_DEBUG_LTSSM_L2)
 
 #define RC_REGION_0_ADDR_TRANS_H		0x00000000
 #define RC_REGION_0_ADDR_TRANS_L		0x00000000
@@ -213,6 +223,7 @@ struct rockchip_pcie {
 	u32     io_size;
 	int     offset;
 	phys_addr_t io_bus_addr;
+	void	__iomem *msg_region;
 	u32     mem_size;
 	phys_addr_t mem_bus_addr;
 };
@@ -1196,8 +1207,91 @@ static int rockchip_cfg_atu(struct rockchip_pcie *rockchip)
 		}
 	}
 
+	/* assign message regions */
+	rockchip_pcie_prog_ob_atu(rockchip, reg_no + 1 + offset,
+				  AXI_WRAPPER_NOR_MSG,
+				  20 - 1, 0, 0);
+	if (!rockchip->msg_region)
+		rockchip->msg_region = devm_ioremap(rockchip->dev,
+						    rockchip->mem_bus_addr +
+						    ((reg_no + offset) << 20),
+						    SZ_1M);
+
 	return err;
 }
+
+static int rockchip_pcie_wait_l2(struct rockchip_pcie *rockchip)
+{
+	u32 value;
+	int err;
+
+	/* send PME_TURN_OFF message */
+	writel(0x0, rockchip->msg_region + PCIE_RC_SEND_PME_OFF);
+
+	/* read LTSSM and wait for falling into L2 link state */
+	err = readl_poll_timeout(rockchip->apb_base + PCIE_CLIENT_DEBUG_OUT_0,
+				 value, PCIE_LINK_IS_L2(value), 20,
+				 jiffies_to_usecs(5 * HZ));
+	if (err) {
+		dev_err(rockchip->dev, "PCIe link enter L2 timeout!\n");
+		return err;
+	}
+
+	return 0;
+}
+
+static int rockchip_pcie_suspend_noirq(struct device *dev)
+{
+	struct rockchip_pcie *rockchip = dev_get_drvdata(dev);
+	int ret;
+
+	/* disable core and cli int since we don't need to ack PME_ACK */
+	rockchip_pcie_write(rockchip, (PCIE_CLIENT_INT_CLI << 16) |
+			    PCIE_CLIENT_INT_CLI, PCIE_CLIENT_INT_MASK);
+	rockchip_pcie_write(rockchip, (u32)PCIE_CORE_INT, PCIE_CORE_INT_MASK);
+
+	ret = rockchip_pcie_wait_l2(rockchip);
+	if (ret) {
+		rockchip_pcie_enable_interrupts(rockchip);
+		return ret;
+	}
+
+	phy_power_off(rockchip->phy);
+	phy_exit(rockchip->phy);
+
+	clk_disable_unprepare(rockchip->clk_pcie_pm);
+	clk_disable_unprepare(rockchip->hclk_pcie);
+	clk_disable_unprepare(rockchip->aclk_perf_pcie);
+	clk_disable_unprepare(rockchip->aclk_pcie);
+
+	return ret;
+}
+
+static int rockchip_pcie_resume_noirq(struct device *dev)
+{
+	struct rockchip_pcie *rockchip = dev_get_drvdata(dev);
+	int err;
+
+	clk_prepare_enable(rockchip->clk_pcie_pm);
+	clk_prepare_enable(rockchip->hclk_pcie);
+	clk_prepare_enable(rockchip->aclk_perf_pcie);
+	clk_prepare_enable(rockchip->aclk_pcie);
+
+	err = rockchip_pcie_init_port(rockchip);
+	if (err)
+		return err;
+
+	err = rockchip_cfg_atu(rockchip);
+	if (err)
+		return err;
+
+	/* Need this to enter L1 again */
+	rockchip_pcie_update_txcredit_mui(rockchip);
+	rockchip_pcie_enable_interrupts(rockchip);
+
+	return 0;
+}
+
 static int rockchip_pcie_probe(struct platform_device *pdev)
 {
 	struct rockchip_pcie *rockchip;
@@ -1218,6 +1312,8 @@ static int rockchip_pcie_probe(struct platform_device *pdev)
 	if (!rockchip)
 		return -ENOMEM;
 
+	platform_set_drvdata(pdev, rockchip);
+
 	rockchip->dev = dev;
 
 	err = rockchip_pcie_parse_dt(rockchip);
@@ -1341,6 +1437,11 @@ static int rockchip_pcie_probe(struct platform_device *pdev)
 	return err;
 }
 
+static const struct dev_pm_ops rockchip_pcie_pm_ops = {
+	SET_NOIRQ_SYSTEM_SLEEP_PM_OPS(rockchip_pcie_suspend_noirq,
+				      rockchip_pcie_resume_noirq)
+};
+
 static const struct of_device_id rockchip_pcie_of_match[] = {
 	{ .compatible = "rockchip,rk3399-pcie", },
 	{}
@@ -1350,6 +1451,7 @@ static int rockchip_pcie_probe(struct platform_device *pdev)
 	.driver = {
 		.name = "rockchip-pcie",
 		.of_match_table = rockchip_pcie_of_match,
+		.pm = &rockchip_pcie_pm_ops,
 	},
 	.probe = rockchip_pcie_probe,
 
-- 
1.9.1