[PATCH v2 3/5] pcie-qcom: provide a way to power up qca6390 chip on RB5 platform

[Dmitry Baryshkov <dmitry.baryshkov@linaro.org>]

Some Qualcomm platforms require to power up an external device before
probing the PCI bus. E.g. on RB5 platform the QCA6390 WiFi/BT chip needs
to be powered up before PCIe0 bus is probed. Add a quirk to the
respective PCIe root bridge to attach to the power domain if one is
required, so that the QCA chip is started before scanning the PCIe bus.

Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
---
 drivers/pci/controller/dwc/pcie-qcom.c | 21 +++++++++++++++++++++
 1 file changed, 21 insertions(+)

diff --git a/drivers/pci/controller/dwc/pcie-qcom.c b/drivers/pci/controller/dwc/pcie-qcom.c
index ab21aa01c95d..eb73c8540d4d 100644
--- a/drivers/pci/controller/dwc/pcie-qcom.c
+++ b/drivers/pci/controller/dwc/pcie-qcom.c
@@ -20,6 +20,7 @@
 #include <linux/of_device.h>
 #include <linux/of_gpio.h>
 #include <linux/pci.h>
+#include <linux/pm_domain.h>
 #include <linux/pm_runtime.h>
 #include <linux/platform_device.h>
 #include <linux/phy/phy.h>
@@ -1568,6 +1569,26 @@ DECLARE_PCI_FIXUP_EARLY(PCI_VENDOR_ID_QCOM, 0x0302, qcom_fixup_class);
 DECLARE_PCI_FIXUP_EARLY(PCI_VENDOR_ID_QCOM, 0x1000, qcom_fixup_class);
 DECLARE_PCI_FIXUP_EARLY(PCI_VENDOR_ID_QCOM, 0x1001, qcom_fixup_class);
 
+static void qcom_fixup_power(struct pci_dev *dev)
+{
+	int ret;
+	struct pcie_port *pp = dev->bus->sysdata;
+	struct dw_pcie *pci;
+
+	if (!pci_is_root_bus(dev->bus))
+		return;
+
+	ret = dev_pm_domain_attach(&dev->dev, true);
+	if (ret < 0 || !dev->dev.pm_domain)
+		return;
+
+	pci = to_dw_pcie_from_pp(pp);
+	dev_info(&dev->dev, "Bus powered up, waiting for link to come up\n");
+
+	dw_pcie_wait_for_link(pci);
+}
+DECLARE_PCI_FIXUP_EARLY(PCI_VENDOR_ID_QCOM, 0x010b, qcom_fixup_power);
+
 static struct platform_driver qcom_pcie_driver = {
 	.probe = qcom_pcie_probe,
 	.driver = {
-- 
2.29.2