On some chips the PCIE and PCIE_PHY blocks are in separate power domains
which can be power-gated independently. The pci driver needs to handle
this by keeping both domain active.

This is intended for imx6sx where PCIE is in DISPLAY and PCIE_PHY in
it's own domain. Defining the DISPLAY domain requires a way for pcie to
keep it active or it will break when displays are off.

The power-domains on imx6sx are meant to look like this:
        power-domains = <&pd_disp>, <&pd_pci>;
        power-domain-names = "pcie", "pcie_phy";

Signed-off-by: Leonard Crestez <leonard.cres...@nxp.com>
Reviewed-by: Ulf Hansson <ulf.hans...@linaro.org>
---
 drivers/pci/controller/dwc/pci-imx6.c | 48 +++++++++++++++++++++++++++
 1 file changed, 48 insertions(+)

diff --git a/drivers/pci/controller/dwc/pci-imx6.c 
b/drivers/pci/controller/dwc/pci-imx6.c
index 6171171db1fc..a482f86b02e6 100644
--- a/drivers/pci/controller/dwc/pci-imx6.c
+++ b/drivers/pci/controller/dwc/pci-imx6.c
@@ -25,10 +25,12 @@
 #include <linux/resource.h>
 #include <linux/signal.h>
 #include <linux/types.h>
 #include <linux/interrupt.h>
 #include <linux/reset.h>
+#include <linux/pm_domain.h>
+#include <linux/pm_runtime.h>
 
 #include "pcie-designware.h"
 
 #define to_imx6_pcie(x)        dev_get_drvdata((x)->dev)
 
@@ -57,10 +59,15 @@ struct imx6_pcie {
        u32                     tx_deemph_gen2_6db;
        u32                     tx_swing_full;
        u32                     tx_swing_low;
        int                     link_gen;
        struct regulator        *vpcie;
+
+       /* power domain for pcie */
+       struct device           *pd_pcie;
+       /* power domain for pcie phy */
+       struct device           *pd_pcie_phy;
 };
 
 /* Parameters for the waiting for PCIe PHY PLL to lock on i.MX7 */
 #define PHY_PLL_LOCK_WAIT_MAX_RETRIES  2000
 #define PHY_PLL_LOCK_WAIT_USLEEP_MIN   50
@@ -290,10 +297,47 @@ static int imx6q_pcie_abort_handler(unsigned long addr,
        }
 
        return 1;
 }
 
+static int imx6_pcie_attach_pd(struct device *dev)
+{
+       struct imx6_pcie *imx6_pcie = dev_get_drvdata(dev);
+       struct device_link *link;
+
+       /* Do nothing when in a single power domain */
+       if (dev->pm_domain)
+               return 0;
+
+       imx6_pcie->pd_pcie = dev_pm_domain_attach_by_name(dev, "pcie");
+       if (IS_ERR(imx6_pcie->pd_pcie))
+               return PTR_ERR(imx6_pcie->pd_pcie);
+       link = device_link_add(dev, imx6_pcie->pd_pcie,
+                       DL_FLAG_STATELESS |
+                       DL_FLAG_PM_RUNTIME |
+                       DL_FLAG_RPM_ACTIVE);
+       if (IS_ERR(link)) {
+               dev_err(dev, "Failed to add device_link to pcie pd: %ld\n", 
PTR_ERR(link));
+               return PTR_ERR(link);
+       }
+
+       imx6_pcie->pd_pcie_phy = dev_pm_domain_attach_by_name(dev, "pcie_phy");
+       if (IS_ERR(imx6_pcie->pd_pcie_phy))
+               return PTR_ERR(imx6_pcie->pd_pcie_phy);
+
+       device_link_add(dev, imx6_pcie->pd_pcie_phy,
+                       DL_FLAG_STATELESS |
+                       DL_FLAG_PM_RUNTIME |
+                       DL_FLAG_RPM_ACTIVE);
+       if (IS_ERR(link)) {
+               dev_err(dev, "Failed to add device_link to pcie_phy pd: %ld\n", 
PTR_ERR(link));
+               return PTR_ERR(link);
+       }
+
+       return 0;
+}
+
 static void imx6_pcie_assert_core_reset(struct imx6_pcie *imx6_pcie)
 {
        struct device *dev = imx6_pcie->pci->dev;
 
        switch (imx6_pcie->variant) {
@@ -1013,10 +1057,14 @@ static int imx6_pcie_probe(struct platform_device *pdev)
                imx6_pcie->vpcie = NULL;
        }
 
        platform_set_drvdata(pdev, imx6_pcie);
 
+       ret = imx6_pcie_attach_pd(dev);
+       if (ret)
+               return ret;
+
        ret = imx6_add_pcie_port(imx6_pcie, pdev);
        if (ret < 0)
                return ret;
 
        return 0;
-- 
2.17.1

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