[PATCH RFC v4 3/9] phy: qcom: qmp-pcie: Add multiple power-domains support

[Qiang Yu <qiang.yu@oss.qualcomm.com>]

The Glymur SoC's 3rd PCIe instance supports 8-lane mode using two PHYs in
a bifurcated configuration. Each PHY has its own power domain (phy_gdsc)
that must be powered on before initialization per hardware requirements.

Current PHY power management assumes a single power domain per PHY,
preventing proper setup for this dual-PHY scenario. Add support for
multiple power domains by using devm_pm_domain_attach_list() to attach
power domains manually, while maintaining compatibility with single
power domain PHYs.

Enable runtime PM to allow power domain control when the PCIe driver
calls phy_power_on/phy_power_off:

- Single power domain: QMP PHY platform device directly attaches to
  power domain and controls it during runtime resume/suspend
- Multiple power domains: devm_pm_domain_attach_list() creates virtual
  devices as power domain suppliers, linked to the QMP PHY platform
  device as consumer

This ensures power domains are properly attached and turned on/off
for both single and multiple power domain configurations.

Reviewed-by: Dmitry Baryshkov <dmitry.baryshkov@oss.qualcomm.com>
Signed-off-by: Qiang Yu <qiang.yu@oss.qualcomm.com>
---
 drivers/phy/qualcomm/phy-qcom-qmp-pcie.c | 12 ++++++++++++
 1 file changed, 12 insertions(+)

diff --git a/drivers/phy/qualcomm/phy-qcom-qmp-pcie.c b/drivers/phy/qualcomm/phy-qcom-qmp-pcie.c
index 75afbd15aaf4..832b5d93105b 100644
--- a/drivers/phy/qualcomm/phy-qcom-qmp-pcie.c
+++ b/drivers/phy/qualcomm/phy-qcom-qmp-pcie.c
@@ -17,6 +17,7 @@
 #include <linux/phy/pcie.h>
 #include <linux/phy/phy.h>
 #include <linux/platform_device.h>
+#include <linux/pm_domain.h>
 #include <linux/regmap.h>
 #include <linux/regulator/consumer.h>
 #include <linux/reset.h>
@@ -5329,6 +5330,7 @@ static int qmp_pcie_parse_dt(struct qmp_pcie *qmp)
 
 static int qmp_pcie_probe(struct platform_device *pdev)
 {
+	struct dev_pm_domain_list *pd_list;
 	struct device *dev = &pdev->dev;
 	struct phy_provider *phy_provider;
 	struct device_node *np;
@@ -5348,6 +5350,16 @@ static int qmp_pcie_probe(struct platform_device *pdev)
 	WARN_ON_ONCE(!qmp->cfg->pwrdn_ctrl);
 	WARN_ON_ONCE(!qmp->cfg->phy_status);
 
+	ret = devm_pm_domain_attach_list(dev, NULL, &pd_list);
+	if (ret < 0 && ret != -EEXIST) {
+		dev_err(dev, "Failed to attach power domain\n");
+		return ret;
+	}
+
+	ret = devm_pm_runtime_enable(dev);
+	if (ret)
+		return ret;
+
 	ret = qmp_pcie_clk_init(qmp);
 	if (ret)
 		return ret;

-- 
2.34.1