[PATCH v3 0/7] PCI/pwrctrl: Major rework to integrate pwrctrl devices with controller drivers

[PATCH v3 0/7] PCI/pwrctrl: Major rework to integrate pwrctrl devices with controller drivers

[Manivannan Sadhasivam via B4 Relay]

Hi,

This series provides a major rework for the PCI power control (pwrctrl)
framework to enable the pwrctrl devices to be controlled by the PCI controller
drivers.

Problem Statement
=================

Currently, the pwrctrl framework faces two major issues:

1. Missing PERST# integration
2. Inability to properly handle bus extenders such as PCIe switch devices

First issue arises from the disconnect between the PCI controller drivers and
pwrctrl framework. At present, the pwrctrl framework just operates on its own
with the help of the PCI core. The pwrctrl devices are created by the PCI core
during initial bus scan and the pwrctrl drivers once bind, just power on the
PCI devices during their probe(). This design conflicts with the PCI Express
Card Electromechanical Specification requirements for PERST# timing. The reason
is, PERST# signals are mostly handled by the controller drivers and often
deasserted even before the pwrctrl drivers probe. According to the spec, PERST#
should be deasserted only after power and reference clock to the device are
stable, within predefined timing parameters.

The second issue stems from the PCI bus scan completing before pwrctrl drivers
probe. This poses a significant problem for PCI bus extenders like switches
because the PCI core allocates upstream bridge resources during the initial
scan. If the upstream bridge is not hotplug capable, resources are allocated
only for the number of downstream buses detected at scan time, which might be
just one if the switch was not powered and enumerated at that time. Later, when
the pwrctrl driver powers on and enumerates the switch, enumeration fails due to
insufficient upstream bridge resources.

Proposal
========

This series addresses both issues by introducing new individual APIs for pwrctrl
device creation, destruction, power on, and power off operations. Controller
drivers are expected to invoke these APIs during their probe(), remove(),
suspend(), and resume() operations. This integration allows better coordination
between controller drivers and the pwrctrl framework, enabling enhanced features
such as D3Cold support.

The original design aimed to avoid modifying controller drivers for pwrctrl
integration. However, this approach lacked scalability because different
controllers have varying requirements for when devices should be powered on. For
example, controller drivers require devices to be powered on early for
successful PHY initialization.

By using these explicit APIs, controller drivers gain fine grained control over
their associated pwrctrl devices.

This series modified the pcie-qcom driver (only consumer of pwrctrl framework)
to adopt to these APIs and also removed the old pwrctrl code from PCI core. This
could be used as a reference to add pwrctrl support for other controller drivers
also.

For example, to control the 3.3v supply to the PCI slot where the NVMe device is
connected, below modifications are required:

Devicetree
----------

	// In SoC dtsi:

	pci@1bf8000 { // controller node
		...
		pcie1_port0: pcie@0 { // PCI Root Port node
			compatible = "pciclass,0604"; // required for pwrctrl
							 driver bind
			...
		};
	};

	// In board dts:

	&pcie1_port0 {
		reset-gpios = <&tlmm 152 GPIO_ACTIVE_LOW>; // optional
		vpcie3v3-supply = <&vreg_nvme>; // NVMe power supply
	};

Controller driver
-----------------

	// Select PCI_PWRCTRL_SLOT in controller Kconfig

	probe() {
		...
		// Initialize controller resources
		pci_pwrctrl_create_devices(&pdev->dev);
		pci_pwrctrl_power_on_devices(&pdev->dev);
		// Deassert PERST# (optional)
		...
		pci_host_probe(); // Allocate host bridge and start bus scan
	}

	suspend {
		// PME_Turn_Off broadcast
		// Assert PERST# (optional)
		pci_pwrctrl_power_off_devices(&pdev->dev);
		...
	}

	resume {
		...
		pci_pwrctrl_power_on_devices(&pdev->dev);
		// Deassert PERST# (optional)
	}

I will add a documentation for the pwrctrl framework in the coming days to make
it easier to use.

Testing
=======

This series is tested on the Lenovo Thinkpad T14s laptop based on Qcom X1E
chipset and RB3Gen2 development board with TC9563 switch based on Qcom QCS6490
chipset.

**NOTE**: With this series, the controller driver may undergo multiple probe
deferral if the pwrctrl driver was not available during the controller driver
probe. This is pretty much required to avoid the resource allocation issue. I
plan to replace probe deferral with blocking wait in the coming days.

Signed-off-by: Manivannan Sadhasivam <manivannan.sadhasivam@oss.qualcomm.com>
---
Changes in v3:
- Integrated TC9563 change
- Reworked the power_on API to properly power off the devices in error path
- Fixed the error path in pcie-qcom.c to not destroy pwrctrl devices during
  probe deferral
- Rebased on top of pci/controller/dwc-qcom branch and dropped the PERST# patch
- Added a patch for TC9563 to fix the refcount dropping for i2c adapter
- Added patches to drop the assert_perst callback and rename the PERST# helpers in
  pcie-qcom.c
- Link to v2: https://lore.kernel.org/r/20251216-pci-pwrctrl-rework-v2-0-745a563b9be6@oss.qualcomm.com

Changes in v2:
- Exported of_pci_supply_present() API
- Demoted the -EPROBE_DEFER log to dev_dbg()
- Collected tags and rebased on top of v6.19-rc1
- Link to v1: https://lore.kernel.org/r/20251124-pci-pwrctrl-rework-v1-0-78a72627683d@oss.qualcomm.com

---
Krishna Chaitanya Chundru (1):
      PCI/pwrctrl: Add APIs for explicitly creating and destroying pwrctrl devices

Manivannan Sadhasivam (6):
      PCI/pwrctrl: tc9563: Use put_device() instead of i2c_put_adapter()
      PCI/pwrctrl: Add 'struct pci_pwrctrl::power_{on/off}' callbacks
      PCI/pwrctrl: Add APIs to power on/off the pwrctrl devices
      PCI/pwrctrl: Switch to the new pwrctrl APIs
      PCI: qcom: Drop the assert_perst() callbacks
      PCI: qcom: Rename PERST# assert/deassert helpers for uniformity

 drivers/pci/bus.c                                 |  19 --
 drivers/pci/controller/dwc/pcie-designware-host.c |   9 -
 drivers/pci/controller/dwc/pcie-designware.h      |   8 -
 drivers/pci/controller/dwc/pcie-qcom.c            |  54 +++--
 drivers/pci/of.c                                  |   1 +
 drivers/pci/probe.c                               |  59 -----
 drivers/pci/pwrctrl/core.c                        | 260 ++++++++++++++++++++--
 drivers/pci/pwrctrl/pci-pwrctrl-pwrseq.c          |  30 ++-
 drivers/pci/pwrctrl/pci-pwrctrl-tc9563.c          |  46 ++--
 drivers/pci/pwrctrl/slot.c                        |  46 ++--
 drivers/pci/remove.c                              |  20 --
 include/linux/pci-pwrctrl.h                       |  16 +-
 include/linux/pci.h                               |   1 -
 13 files changed, 363 insertions(+), 206 deletions(-)
---
base-commit: 3e7f562e20ee87a25e104ef4fce557d39d62fa85
change-id: 20251124-pci-pwrctrl-rework-c91a6e16c2f6
prerequisite-message-id: 20251126081718.8239-1-mani@kernel.org
prerequisite-patch-id: db9ff6c713e2303c397e645935280fd0d277793a
prerequisite-patch-id: b5351b0a41f618435f973ea2c3275e51d46f01c5

Best regards,
-- 
Manivannan Sadhasivam <manivannan.sadhasivam@oss.qualcomm.com>

[PATCH v3 1/7] PCI/pwrctrl: tc9563: Use put_device() instead of i2c_put_adapter()

[Manivannan Sadhasivam via B4 Relay]

From: Manivannan Sadhasivam <manivannan.sadhasivam@oss.qualcomm.com>

The API comment for of_find_i2c_adapter_by_node() recommends using
put_device() to drop the reference count of I2C adapter instead of using
i2c_put_adapter(). So replace i2c_put_adapter() with put_device().

Fixes: 4c9c7be47310 ("PCI: pwrctrl: Add power control driver for TC9563")
Signed-off-by: Manivannan Sadhasivam <manivannan.sadhasivam@oss.qualcomm.com>
---
 drivers/pci/pwrctrl/pci-pwrctrl-tc9563.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/drivers/pci/pwrctrl/pci-pwrctrl-tc9563.c b/drivers/pci/pwrctrl/pci-pwrctrl-tc9563.c
index ec423432ac65..0a63add84d09 100644
--- a/drivers/pci/pwrctrl/pci-pwrctrl-tc9563.c
+++ b/drivers/pci/pwrctrl/pci-pwrctrl-tc9563.c
@@ -533,7 +533,7 @@ static int tc9563_pwrctrl_probe(struct platform_device *pdev)
 	ctx->client = i2c_new_dummy_device(ctx->adapter, addr);
 	if (IS_ERR(ctx->client)) {
 		dev_err(dev, "Failed to create I2C client\n");
-		i2c_put_adapter(ctx->adapter);
+		put_device(&ctx->adapter->dev);
 		return PTR_ERR(ctx->client);
 	}
 
@@ -613,7 +613,7 @@ static int tc9563_pwrctrl_probe(struct platform_device *pdev)
 	tc9563_pwrctrl_power_off(ctx);
 remove_i2c:
 	i2c_unregister_device(ctx->client);
-	i2c_put_adapter(ctx->adapter);
+	put_device(&ctx->adapter->dev);
 	return ret;
 }
 
@@ -623,7 +623,7 @@ static void tc9563_pwrctrl_remove(struct platform_device *pdev)
 
 	tc9563_pwrctrl_power_off(ctx);
 	i2c_unregister_device(ctx->client);
-	i2c_put_adapter(ctx->adapter);
+	put_device(&ctx->adapter->dev);
 }
 
 static const struct of_device_id tc9563_pwrctrl_of_match[] = {

-- 
2.48.1

[PATCH v3 2/7] PCI/pwrctrl: Add 'struct pci_pwrctrl::power_{on/off}' callbacks

[Manivannan Sadhasivam via B4 Relay]

From: Manivannan Sadhasivam <manivannan.sadhasivam@oss.qualcomm.com>

To allow the pwrctrl core to control the power on/off sequences of the
pwrctrl drivers, add the 'struct pci_pwrctrl::power_{on/off}' callbacks and
populate them in the respective pwrctrl drivers.

The pwrctrl drivers still power on the resources on their own now. So there
is no functional change.

Co-developed-by: Krishna Chaitanya Chundru <krishna.chundru@oss.qualcomm.com>
Signed-off-by: Krishna Chaitanya Chundru <krishna.chundru@oss.qualcomm.com>
Tested-by: Chen-Yu Tsai <wenst@chromium.org>
Signed-off-by: Manivannan Sadhasivam <manivannan.sadhasivam@oss.qualcomm.com>
---
 drivers/pci/pwrctrl/pci-pwrctrl-pwrseq.c | 27 +++++++++++++++---
 drivers/pci/pwrctrl/pci-pwrctrl-tc9563.c | 20 +++++++++----
 drivers/pci/pwrctrl/slot.c               | 48 ++++++++++++++++++++++----------
 include/linux/pci-pwrctrl.h              |  4 +++
 4 files changed, 75 insertions(+), 24 deletions(-)

diff --git a/drivers/pci/pwrctrl/pci-pwrctrl-pwrseq.c b/drivers/pci/pwrctrl/pci-pwrctrl-pwrseq.c
index 4e664e7b8dd2..0fb9038a1d18 100644
--- a/drivers/pci/pwrctrl/pci-pwrctrl-pwrseq.c
+++ b/drivers/pci/pwrctrl/pci-pwrctrl-pwrseq.c
@@ -52,11 +52,27 @@ static const struct pci_pwrctrl_pwrseq_pdata pci_pwrctrl_pwrseq_qcom_wcn_pdata =
 	.validate_device = pci_pwrctrl_pwrseq_qcm_wcn_validate_device,
 };
 
+static int pci_pwrctrl_pwrseq_power_on(struct pci_pwrctrl *ctx)
+{
+	struct pci_pwrctrl_pwrseq_data *data = container_of(ctx, struct pci_pwrctrl_pwrseq_data,
+							    ctx);
+
+	return pwrseq_power_on(data->pwrseq);
+}
+
+static void pci_pwrctrl_pwrseq_power_off(struct pci_pwrctrl *ctx)
+{
+	struct pci_pwrctrl_pwrseq_data *data = container_of(ctx, struct pci_pwrctrl_pwrseq_data,
+							    ctx);
+
+	pwrseq_power_off(data->pwrseq);
+}
+
 static void devm_pci_pwrctrl_pwrseq_power_off(void *data)
 {
-	struct pwrseq_desc *pwrseq = data;
+	struct pci_pwrctrl_pwrseq_data *pwrseq_data = data;
 
-	pwrseq_power_off(pwrseq);
+	pci_pwrctrl_pwrseq_power_off(&pwrseq_data->ctx);
 }
 
 static int pci_pwrctrl_pwrseq_probe(struct platform_device *pdev)
@@ -85,16 +101,19 @@ static int pci_pwrctrl_pwrseq_probe(struct platform_device *pdev)
 		return dev_err_probe(dev, PTR_ERR(data->pwrseq),
 				     "Failed to get the power sequencer\n");
 
-	ret = pwrseq_power_on(data->pwrseq);
+	ret = pci_pwrctrl_pwrseq_power_on(&data->ctx);
 	if (ret)
 		return dev_err_probe(dev, ret,
 				     "Failed to power-on the device\n");
 
 	ret = devm_add_action_or_reset(dev, devm_pci_pwrctrl_pwrseq_power_off,
-				       data->pwrseq);
+				       data);
 	if (ret)
 		return ret;
 
+	data->ctx.power_on = pci_pwrctrl_pwrseq_power_on;
+	data->ctx.power_off = pci_pwrctrl_pwrseq_power_off;
+
 	pci_pwrctrl_init(&data->ctx, dev);
 
 	ret = devm_pci_pwrctrl_device_set_ready(dev, &data->ctx);
diff --git a/drivers/pci/pwrctrl/pci-pwrctrl-tc9563.c b/drivers/pci/pwrctrl/pci-pwrctrl-tc9563.c
index 0a63add84d09..0393af2a099c 100644
--- a/drivers/pci/pwrctrl/pci-pwrctrl-tc9563.c
+++ b/drivers/pci/pwrctrl/pci-pwrctrl-tc9563.c
@@ -434,15 +434,20 @@ static int tc9563_pwrctrl_parse_device_dt(struct tc9563_pwrctrl_ctx *ctx, struct
 	return 0;
 }
 
-static void tc9563_pwrctrl_power_off(struct tc9563_pwrctrl_ctx *ctx)
+static void tc9563_pwrctrl_power_off(struct pci_pwrctrl *pwrctrl)
 {
+	struct tc9563_pwrctrl_ctx *ctx = container_of(pwrctrl,
+					struct tc9563_pwrctrl_ctx, pwrctrl);
+
 	gpiod_set_value(ctx->reset_gpio, 1);
 
 	regulator_bulk_disable(ARRAY_SIZE(ctx->supplies), ctx->supplies);
 }
 
-static int tc9563_pwrctrl_bring_up(struct tc9563_pwrctrl_ctx *ctx)
+static int tc9563_pwrctrl_power_on(struct pci_pwrctrl *pwrctrl)
 {
+	struct tc9563_pwrctrl_ctx *ctx = container_of(pwrctrl,
+					struct tc9563_pwrctrl_ctx, pwrctrl);
 	struct tc9563_pwrctrl_cfg *cfg;
 	int ret, i;
 
@@ -502,7 +507,7 @@ static int tc9563_pwrctrl_bring_up(struct tc9563_pwrctrl_ctx *ctx)
 		return 0;
 
 power_off:
-	tc9563_pwrctrl_power_off(ctx);
+	tc9563_pwrctrl_power_off(&ctx->pwrctrl);
 	return ret;
 }
 
@@ -591,7 +596,7 @@ static int tc9563_pwrctrl_probe(struct platform_device *pdev)
 			goto remove_i2c;
 	}
 
-	ret = tc9563_pwrctrl_bring_up(ctx);
+	ret = tc9563_pwrctrl_power_on(&ctx->pwrctrl);
 	if (ret)
 		goto remove_i2c;
 
@@ -601,6 +606,9 @@ static int tc9563_pwrctrl_probe(struct platform_device *pdev)
 			goto power_off;
 	}
 
+	ctx->pwrctrl.power_on = tc9563_pwrctrl_power_on;
+	ctx->pwrctrl.power_off = tc9563_pwrctrl_power_off;
+
 	ret = devm_pci_pwrctrl_device_set_ready(dev, &ctx->pwrctrl);
 	if (ret)
 		goto power_off;
@@ -610,7 +618,7 @@ static int tc9563_pwrctrl_probe(struct platform_device *pdev)
 	return 0;
 
 power_off:
-	tc9563_pwrctrl_power_off(ctx);
+	tc9563_pwrctrl_power_off(&ctx->pwrctrl);
 remove_i2c:
 	i2c_unregister_device(ctx->client);
 	put_device(&ctx->adapter->dev);
@@ -621,7 +629,7 @@ static void tc9563_pwrctrl_remove(struct platform_device *pdev)
 {
 	struct tc9563_pwrctrl_ctx *ctx = platform_get_drvdata(pdev);
 
-	tc9563_pwrctrl_power_off(ctx);
+	tc9563_pwrctrl_power_off(&ctx->pwrctrl);
 	i2c_unregister_device(ctx->client);
 	put_device(&ctx->adapter->dev);
 }
diff --git a/drivers/pci/pwrctrl/slot.c b/drivers/pci/pwrctrl/slot.c
index 3320494b62d8..14701f65f1f2 100644
--- a/drivers/pci/pwrctrl/slot.c
+++ b/drivers/pci/pwrctrl/slot.c
@@ -17,13 +17,36 @@ struct pci_pwrctrl_slot_data {
 	struct pci_pwrctrl ctx;
 	struct regulator_bulk_data *supplies;
 	int num_supplies;
+	struct clk *clk;
 };
 
-static void devm_pci_pwrctrl_slot_power_off(void *data)
+static int pci_pwrctrl_slot_power_on(struct pci_pwrctrl *ctx)
 {
-	struct pci_pwrctrl_slot_data *slot = data;
+	struct pci_pwrctrl_slot_data *slot = container_of(ctx, struct pci_pwrctrl_slot_data, ctx);
+	int ret;
+
+	ret = regulator_bulk_enable(slot->num_supplies, slot->supplies);
+	if (ret < 0) {
+		dev_err(slot->ctx.dev, "Failed to enable slot regulators\n");
+		return ret;
+	}
+
+	return clk_prepare_enable(slot->clk);
+}
+
+static void pci_pwrctrl_slot_power_off(struct pci_pwrctrl *ctx)
+{
+	struct pci_pwrctrl_slot_data *slot = container_of(ctx, struct pci_pwrctrl_slot_data, ctx);
 
 	regulator_bulk_disable(slot->num_supplies, slot->supplies);
+	clk_disable_unprepare(slot->clk);
+}
+
+static void devm_pci_pwrctrl_slot_release(void *data)
+{
+	struct pci_pwrctrl_slot_data *slot = data;
+
+	pci_pwrctrl_slot_power_off(&slot->ctx);
 	regulator_bulk_free(slot->num_supplies, slot->supplies);
 }
 
@@ -31,7 +54,6 @@ static int pci_pwrctrl_slot_probe(struct platform_device *pdev)
 {
 	struct pci_pwrctrl_slot_data *slot;
 	struct device *dev = &pdev->dev;
-	struct clk *clk;
 	int ret;
 
 	slot = devm_kzalloc(dev, sizeof(*slot), GFP_KERNEL);
@@ -46,23 +68,21 @@ static int pci_pwrctrl_slot_probe(struct platform_device *pdev)
 	}
 
 	slot->num_supplies = ret;
-	ret = regulator_bulk_enable(slot->num_supplies, slot->supplies);
-	if (ret < 0) {
-		dev_err_probe(dev, ret, "Failed to enable slot regulators\n");
-		regulator_bulk_free(slot->num_supplies, slot->supplies);
-		return ret;
-	}
 
-	ret = devm_add_action_or_reset(dev, devm_pci_pwrctrl_slot_power_off,
+	ret = devm_add_action_or_reset(dev, devm_pci_pwrctrl_slot_release,
 				       slot);
 	if (ret)
 		return ret;
 
-	clk = devm_clk_get_optional_enabled(dev, NULL);
-	if (IS_ERR(clk)) {
-		return dev_err_probe(dev, PTR_ERR(clk),
+	slot->clk = devm_clk_get_optional(dev, NULL);
+	if (IS_ERR(slot->clk))
+		return dev_err_probe(dev, PTR_ERR(slot->clk),
 				     "Failed to enable slot clock\n");
-	}
+
+	pci_pwrctrl_slot_power_on(&slot->ctx);
+
+	slot->ctx.power_on = pci_pwrctrl_slot_power_on;
+	slot->ctx.power_off = pci_pwrctrl_slot_power_off;
 
 	pci_pwrctrl_init(&slot->ctx, dev);
 
diff --git a/include/linux/pci-pwrctrl.h b/include/linux/pci-pwrctrl.h
index 4aefc7901cd1..bd0ee9998125 100644
--- a/include/linux/pci-pwrctrl.h
+++ b/include/linux/pci-pwrctrl.h
@@ -31,6 +31,8 @@ struct device_link;
 /**
  * struct pci_pwrctrl - PCI device power control context.
  * @dev: Address of the power controlling device.
+ * @power_on: Callback to power on the power controlling device.
+ * @power_off: Callback to power off the power controlling device.
  *
  * An object of this type must be allocated by the PCI power control device and
  * passed to the pwrctrl subsystem to trigger a bus rescan and setup a device
@@ -38,6 +40,8 @@ struct device_link;
  */
 struct pci_pwrctrl {
 	struct device *dev;
+	int (*power_on)(struct pci_pwrctrl *pwrctrl);
+	void (*power_off)(struct pci_pwrctrl *pwrctrl);
 
 	/* private: internal use only */
 	struct notifier_block nb;

-- 
2.48.1

[PATCH v3 3/7] PCI/pwrctrl: Add APIs for explicitly creating and destroying pwrctrl devices

[Manivannan Sadhasivam via B4 Relay]

From: Krishna Chaitanya Chundru <krishna.chundru@oss.qualcomm.com>

Previously, the PCI core created pwrctrl devices during pci_scan_device()
on its own and then skipped enumeration of those devices, hoping the
pwrctrl driver would power them on and trigger a bus rescan.

This approach works for endpoint devices directly connected to Root Ports,
but it fails for PCIe switches acting as bus extenders. When the switch
requires pwrctrl support, and the pwrctrl driver is not available during
the pwrctrl device creation, it's enumeration will be skipped during the
initial PCI bus scan.

This premature scan leads the PCI core to allocate resources (bridge
windows, bus numbers) for the upstream bridge based on available downstream
buses at scan time. For non-hotplug capable bridges, PCI core typically
allocates resources based on the number of buses available during the
initial bus scan, which happens to be just one if the switch is not powered
on and enumerated at that time. When the switch gets enumerated later on,
it will fail due to the lack of upstream resources.

As a result, a PCIe switch powered on by the pwrctrl driver cannot be
reliably enumerated currently. Either the switch has to be enabled in the
bootloader or the switch pwrctrl driver has to be loaded during the pwrctrl
device creation time to workaround these issues.

This commit introduces new APIs to explicitly create and destroy pwrctrl
devices from controller drivers by recursively scanning the PCI child nodes
of the controller. These APIs allow creating pwrctrl devices based on the
original criteria and are intended to be called during controller probe and
removal.

These APIs, together with the upcoming APIs for power on/off will allow the
controller drivers to power on all the devices before starting the initial
bus scan, thereby solving the resource allocation issue.

Signed-off-by: Krishna Chaitanya Chundru <krishna.chundru@oss.qualcomm.com>
[mani: splitted the patch, cleaned up the code, and rewrote description]
Tested-by: Chen-Yu Tsai <wenst@chromium.org>
Signed-off-by: Manivannan Sadhasivam <manivannan.sadhasivam@oss.qualcomm.com>
---
 drivers/pci/of.c            |   1 +
 drivers/pci/pwrctrl/core.c  | 113 ++++++++++++++++++++++++++++++++++++++++++++
 include/linux/pci-pwrctrl.h |   8 +++-
 3 files changed, 121 insertions(+), 1 deletion(-)

diff --git a/drivers/pci/of.c b/drivers/pci/of.c
index 3579265f1198..9bb5f258759b 100644
--- a/drivers/pci/of.c
+++ b/drivers/pci/of.c
@@ -867,6 +867,7 @@ bool of_pci_supply_present(struct device_node *np)
 
 	return false;
 }
+EXPORT_SYMBOL_GPL(of_pci_supply_present);
 
 #endif /* CONFIG_PCI */
 
diff --git a/drivers/pci/pwrctrl/core.c b/drivers/pci/pwrctrl/core.c
index 6bdbfed584d6..844b5649b663 100644
--- a/drivers/pci/pwrctrl/core.c
+++ b/drivers/pci/pwrctrl/core.c
@@ -3,14 +3,21 @@
  * Copyright (C) 2024 Linaro Ltd.
  */
 
+#define dev_fmt(fmt) "Pwrctrl: " fmt
+
 #include <linux/device.h>
 #include <linux/export.h>
 #include <linux/kernel.h>
+#include <linux/of.h>
+#include <linux/of_platform.h>
 #include <linux/pci.h>
 #include <linux/pci-pwrctrl.h>
+#include <linux/platform_device.h>
 #include <linux/property.h>
 #include <linux/slab.h>
 
+#include "../pci.h"
+
 static int pci_pwrctrl_notify(struct notifier_block *nb, unsigned long action,
 			      void *data)
 {
@@ -145,6 +152,112 @@ int devm_pci_pwrctrl_device_set_ready(struct device *dev,
 }
 EXPORT_SYMBOL_GPL(devm_pci_pwrctrl_device_set_ready);
 
+static int pci_pwrctrl_create_device(struct device_node *np, struct device *parent)
+{
+	struct platform_device *pdev;
+	int ret;
+
+	for_each_available_child_of_node_scoped(np, child) {
+		ret = pci_pwrctrl_create_device(child, parent);
+		if (ret)
+			return ret;
+	}
+
+	/* Bail out if the platform device is already available for the node */
+	pdev = of_find_device_by_node(np);
+	if (pdev) {
+		put_device(&pdev->dev);
+		return 0;
+	}
+
+	/*
+	 * Sanity check to make sure that the node has the compatible property
+	 * to allow driver binding.
+	 */
+	if (!of_property_present(np, "compatible"))
+		return 0;
+
+	/*
+	 * Check whether the pwrctrl device really needs to be created or not.
+	 * This is decided based on at least one of the power supplies being
+	 * defined in the devicetree node of the device.
+	 */
+	if (!of_pci_supply_present(np)) {
+		dev_dbg(parent, "Skipping OF node: %s\n", np->name);
+		return 0;
+	}
+
+	/* Now create the pwrctrl device */
+	pdev = of_platform_device_create(np, NULL, parent);
+	if (!pdev) {
+		dev_err(parent, "Failed to create pwrctrl device for node: %s\n", np->name);
+		return -EINVAL;
+	}
+
+	return 0;
+}
+
+/**
+ * pci_pwrctrl_create_devices - Create pwrctrl devices
+ *
+ * @parent: Parent PCI device for which the pwrctrl devices need to be created.
+ *
+ * This function recursively creates pwrctrl devices for the child nodes
+ * of the specified PCI parent device in a depth first manner. On error, all
+ * created devices will be destroyed.
+ *
+ * Returns: 0 on success, negative error number on error.
+ */
+int pci_pwrctrl_create_devices(struct device *parent)
+{
+	int ret;
+
+	for_each_available_child_of_node_scoped(parent->of_node, child) {
+		ret = pci_pwrctrl_create_device(child, parent);
+		if (ret) {
+			pci_pwrctrl_destroy_devices(parent);
+			return ret;
+		}
+	}
+
+	return 0;
+}
+EXPORT_SYMBOL_GPL(pci_pwrctrl_create_devices);
+
+static void pci_pwrctrl_destroy_device(struct device_node *np)
+{
+	struct platform_device *pdev;
+
+	for_each_available_child_of_node_scoped(np, child)
+		pci_pwrctrl_destroy_device(child);
+
+	pdev = of_find_device_by_node(np);
+	if (!pdev)
+		return;
+
+	of_device_unregister(pdev);
+	put_device(&pdev->dev);
+
+	of_node_clear_flag(np, OF_POPULATED);
+}
+
+/**
+ * pci_pwrctrl_destroy_devices - Destroy pwrctrl devices
+ *
+ * @parent: Parent PCI device for which the pwrctrl devices need to be destroyed.
+ *
+ * This function recursively destroys pwrctrl devices for the child nodes
+ * of the specified PCI parent device in a depth first manner.
+ */
+void pci_pwrctrl_destroy_devices(struct device *parent)
+{
+	struct device_node *np = parent->of_node;
+
+	for_each_available_child_of_node_scoped(np, child)
+		pci_pwrctrl_destroy_device(child);
+}
+EXPORT_SYMBOL_GPL(pci_pwrctrl_destroy_devices);
+
 MODULE_AUTHOR("Bartosz Golaszewski <bartosz.golaszewski@linaro.org>");
 MODULE_DESCRIPTION("PCI Device Power Control core driver");
 MODULE_LICENSE("GPL");
diff --git a/include/linux/pci-pwrctrl.h b/include/linux/pci-pwrctrl.h
index bd0ee9998125..5590ffec0bea 100644
--- a/include/linux/pci-pwrctrl.h
+++ b/include/linux/pci-pwrctrl.h
@@ -54,5 +54,11 @@ int pci_pwrctrl_device_set_ready(struct pci_pwrctrl *pwrctrl);
 void pci_pwrctrl_device_unset_ready(struct pci_pwrctrl *pwrctrl);
 int devm_pci_pwrctrl_device_set_ready(struct device *dev,
 				     struct pci_pwrctrl *pwrctrl);
-
+#if IS_ENABLED(CONFIG_PCI_PWRCTRL)
+int pci_pwrctrl_create_devices(struct device *parent);
+void pci_pwrctrl_destroy_devices(struct device *parent);
+#else
+static inline int pci_pwrctrl_create_devices(struct device *parent) { return 0; }
+static void pci_pwrctrl_destroy_devices(struct device *parent) { }
+#endif
 #endif /* __PCI_PWRCTRL_H__ */

-- 
2.48.1

[PATCH v3 4/7] PCI/pwrctrl: Add APIs to power on/off the pwrctrl devices

[Manivannan Sadhasivam via B4 Relay]

From: Manivannan Sadhasivam <manivannan.sadhasivam@oss.qualcomm.com>

To fix PCIe bridge resource allocation issues when powering PCIe
switches with the pwrctrl driver, introduce APIs to explicitly power
on and off all related devices simultaneously.

Previously, the individual pwrctrl drivers powered on/off the PCIe devices
autonomously, without any control from the controller drivers. But to
enforce ordering w.r.t powering on the devices, these APIs will power
on/off all the devices at the same time.

The pci_pwrctrl_power_on_devices() API recursively scans the PCI child
nodes, makes sure that pwrctrl drivers are bind to devices, and calls their
power_on() callbacks. If any of the pwrctrl driver is not bound, it will
return -EPROBE_DEFER.

Similarly, pci_pwrctrl_power_off_devices() API powers off devices
recursively via their power_off() callbacks.

These APIs are expected to be called during the controller probe and
suspend/resume time to power on/off the devices. But before calling these
APIs, the pwrctrl devices should've been created beforehand using the
pci_pwrctrl_{create/destroy}_devices() APIs.

Co-developed-by: Krishna Chaitanya Chundru <krishna.chundru@oss.qualcomm.com>
Signed-off-by: Krishna Chaitanya Chundru <krishna.chundru@oss.qualcomm.com>
Tested-by: Chen-Yu Tsai <wenst@chromium.org>
Reviewed-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
Signed-off-by: Manivannan Sadhasivam <manivannan.sadhasivam@oss.qualcomm.com>
---
 drivers/pci/pwrctrl/core.c  | 132 ++++++++++++++++++++++++++++++++++++++++++++
 include/linux/pci-pwrctrl.h |   4 ++
 2 files changed, 136 insertions(+)

diff --git a/drivers/pci/pwrctrl/core.c b/drivers/pci/pwrctrl/core.c
index 844b5649b663..0ca448f3bea8 100644
--- a/drivers/pci/pwrctrl/core.c
+++ b/drivers/pci/pwrctrl/core.c
@@ -65,6 +65,7 @@ void pci_pwrctrl_init(struct pci_pwrctrl *pwrctrl, struct device *dev)
 {
 	pwrctrl->dev = dev;
 	INIT_WORK(&pwrctrl->work, rescan_work_func);
+	dev_set_drvdata(dev, pwrctrl);
 }
 EXPORT_SYMBOL_GPL(pci_pwrctrl_init);
 
@@ -152,6 +153,137 @@ int devm_pci_pwrctrl_device_set_ready(struct device *dev,
 }
 EXPORT_SYMBOL_GPL(devm_pci_pwrctrl_device_set_ready);
 
+static void __pci_pwrctrl_power_off_device(struct device *dev)
+{
+	struct pci_pwrctrl *pwrctrl = dev_get_drvdata(dev);
+
+	if (!pwrctrl)
+		return;
+
+	return pwrctrl->power_off(pwrctrl);
+}
+
+static int pci_pwrctrl_power_off_device(struct device_node *np)
+{
+	struct platform_device *pdev;
+
+	for_each_available_child_of_node_scoped(np, child)
+		pci_pwrctrl_power_off_device(child);
+
+	pdev = of_find_device_by_node(np);
+	if (pdev) {
+		if (device_is_bound(&pdev->dev))
+			__pci_pwrctrl_power_off_device(&pdev->dev);
+
+		put_device(&pdev->dev);
+	}
+
+	return 0;
+}
+
+/**
+ * pci_pwrctrl_power_off_devices - Power off the pwrctrl devices
+ *
+ * @parent: Parent PCI device for which the pwrctrl devices need to be powered
+ * off.
+ *
+ * This function recursively traverses all pwrctrl devices for the child nodes
+ * of the specified PCI parent device, and powers them off in a depth first
+ * manner.
+ *
+ * Returns: 0 on success, negative error number on error.
+ */
+void pci_pwrctrl_power_off_devices(struct device *parent)
+{
+	struct device_node *np = parent->of_node;
+
+	for_each_available_child_of_node_scoped(np, child)
+		pci_pwrctrl_power_off_device(child);
+}
+EXPORT_SYMBOL_GPL(pci_pwrctrl_power_off_devices);
+
+static int __pci_pwrctrl_power_on_device(struct device *dev)
+{
+	struct pci_pwrctrl *pwrctrl = dev_get_drvdata(dev);
+
+	if (!pwrctrl)
+		return 0;
+
+	return pwrctrl->power_on(pwrctrl);
+}
+
+/*
+ * Power on the devices in a depth first manner. Before powering on the device,
+ * make sure its driver is bound.
+ */
+static int pci_pwrctrl_power_on_device(struct device_node *np)
+{
+	struct platform_device *pdev;
+	int ret;
+
+	for_each_available_child_of_node_scoped(np, child) {
+		ret = pci_pwrctrl_power_on_device(child);
+		if (ret)
+			return ret;
+	}
+
+	pdev = of_find_device_by_node(np);
+	if (pdev) {
+		if (!device_is_bound(&pdev->dev)) {
+			/* FIXME: Use blocking wait instead of probe deferral */
+			dev_dbg(&pdev->dev, "driver is not bound\n");
+			ret = -EPROBE_DEFER;
+		} else {
+			ret = __pci_pwrctrl_power_on_device(&pdev->dev);
+		}
+		put_device(&pdev->dev);
+
+		if (ret)
+			return ret;
+	}
+
+	return 0;
+}
+
+/**
+ * pci_pwrctrl_power_on_devices - Power on the pwrctrl devices
+ *
+ * @parent: Parent PCI device for which the pwrctrl devices need to be powered
+ * on.
+ *
+ * This function recursively traverses all pwrctrl devices for the child nodes
+ * of the specified PCI parent device, and powers them on in a depth first
+ * manner. On error, all powered on devices will be powered off.
+ *
+ * Returns: 0 on success, -EPROBE_DEFER if any pwrctrl driver is not bound, an
+ * appropriate error code otherwise.
+ */
+int pci_pwrctrl_power_on_devices(struct device *parent)
+{
+	struct device_node *np = parent->of_node;
+	struct device_node *child = NULL;
+	int ret;
+
+	for_each_available_child_of_node(np, child) {
+		ret = pci_pwrctrl_power_on_device(child);
+		if (ret)
+			goto err_power_off;
+	}
+
+	return 0;
+
+err_power_off:
+	for_each_available_child_of_node_scoped(np, tmp) {
+		if (tmp == child)
+			break;
+		pci_pwrctrl_power_off_device(tmp);
+	}
+	of_node_put(child);
+
+	return ret;
+}
+EXPORT_SYMBOL_GPL(pci_pwrctrl_power_on_devices);
+
 static int pci_pwrctrl_create_device(struct device_node *np, struct device *parent)
 {
 	struct platform_device *pdev;
diff --git a/include/linux/pci-pwrctrl.h b/include/linux/pci-pwrctrl.h
index 5590ffec0bea..1b77769eebbe 100644
--- a/include/linux/pci-pwrctrl.h
+++ b/include/linux/pci-pwrctrl.h
@@ -57,8 +57,12 @@ int devm_pci_pwrctrl_device_set_ready(struct device *dev,
 #if IS_ENABLED(CONFIG_PCI_PWRCTRL)
 int pci_pwrctrl_create_devices(struct device *parent);
 void pci_pwrctrl_destroy_devices(struct device *parent);
+int pci_pwrctrl_power_on_devices(struct device *parent);
+void pci_pwrctrl_power_off_devices(struct device *parent);
 #else
 static inline int pci_pwrctrl_create_devices(struct device *parent) { return 0; }
 static void pci_pwrctrl_destroy_devices(struct device *parent) { }
+static inline int pci_pwrctrl_power_on_devices(struct device *parent) { return 0; }
+static void pci_pwrctrl_power_off_devices(struct device *parent) { }
 #endif
 #endif /* __PCI_PWRCTRL_H__ */

-- 
2.48.1

[PATCH v3 5/7] PCI/pwrctrl: Switch to the new pwrctrl APIs

[Manivannan Sadhasivam via B4 Relay]

From: Manivannan Sadhasivam <manivannan.sadhasivam@oss.qualcomm.com>

Adopt the recently introduced pwrctrl APIs to create, power on, destroy,
and power off pwrctrl devices. In qcom_pcie_host_init(), call
pci_pwrctrl_create_devices() to create devices, then
pci_pwrctrl_power_on_devices() to power them on, both after controller
resource initialization. Once successful, deassert PERST# for all devices.

In qcom_pcie_host_deinit(), call pci_pwrctrl_power_off_devices() after
asserting PERST#. Note that pci_pwrctrl_destroy_devices() is not called
here, as deinit is only invoked during system suspend where device
destruction is unnecessary. If the driver becomes removable in future,
pci_pwrctrl_destroy_devices() should be called in the remove() handler.

At last, remove the old pwrctrl framework code from the PCI core (including
devlinks) as the new APIs are now the sole consumer of pwrctrl
functionality. And also do not power on the pwrctrl drivers during probe()
as this is now handled by the APIs.

Co-developed-by: Krishna Chaitanya Chundru <krishna.chundru@oss.qualcomm.com>
Signed-off-by: Krishna Chaitanya Chundru <krishna.chundru@oss.qualcomm.com>
Tested-by: Chen-Yu Tsai <wenst@chromium.org>
Signed-off-by: Manivannan Sadhasivam <manivannan.sadhasivam@oss.qualcomm.com>
---
 drivers/pci/bus.c                        | 19 ----------
 drivers/pci/controller/dwc/pcie-qcom.c   | 23 +++++++++++--
 drivers/pci/probe.c                      | 59 --------------------------------
 drivers/pci/pwrctrl/core.c               | 15 --------
 drivers/pci/pwrctrl/pci-pwrctrl-pwrseq.c |  5 ---
 drivers/pci/pwrctrl/pci-pwrctrl-tc9563.c | 24 ++-----------
 drivers/pci/pwrctrl/slot.c               |  2 --
 drivers/pci/remove.c                     | 20 -----------
 8 files changed, 24 insertions(+), 143 deletions(-)

diff --git a/drivers/pci/bus.c b/drivers/pci/bus.c
index 4383a36fd6ca..d60d5f108212 100644
--- a/drivers/pci/bus.c
+++ b/drivers/pci/bus.c
@@ -344,7 +344,6 @@ void __weak pcibios_bus_add_device(struct pci_dev *pdev) { }
 void pci_bus_add_device(struct pci_dev *dev)
 {
 	struct device_node *dn = dev->dev.of_node;
-	struct platform_device *pdev;
 
 	/*
 	 * Can not put in pci_device_add yet because resources
@@ -361,24 +360,6 @@ void pci_bus_add_device(struct pci_dev *dev)
 	/* Save config space for error recoverability */
 	pci_save_state(dev);
 
-	/*
-	 * If the PCI device is associated with a pwrctrl device with a
-	 * power supply, create a device link between the PCI device and
-	 * pwrctrl device.  This ensures that pwrctrl drivers are probed
-	 * before PCI client drivers.
-	 */
-	pdev = of_find_device_by_node(dn);
-	if (pdev) {
-		if (of_pci_supply_present(dn)) {
-			if (!device_link_add(&dev->dev, &pdev->dev,
-					     DL_FLAG_AUTOREMOVE_CONSUMER)) {
-				pci_err(dev, "failed to add device link to power control device %s\n",
-					pdev->name);
-			}
-		}
-		put_device(&pdev->dev);
-	}
-
 	if (!dn || of_device_is_available(dn))
 		pci_dev_allow_binding(dev);
 
diff --git a/drivers/pci/controller/dwc/pcie-qcom.c b/drivers/pci/controller/dwc/pcie-qcom.c
index 1ca58d0264e3..198befb5be2c 100644
--- a/drivers/pci/controller/dwc/pcie-qcom.c
+++ b/drivers/pci/controller/dwc/pcie-qcom.c
@@ -24,6 +24,7 @@
 #include <linux/of_pci.h>
 #include <linux/pci.h>
 #include <linux/pci-ecam.h>
+#include <linux/pci-pwrctrl.h>
 #include <linux/pm_opp.h>
 #include <linux/pm_runtime.h>
 #include <linux/platform_device.h>
@@ -1317,10 +1318,18 @@ static int qcom_pcie_host_init(struct dw_pcie_rp *pp)
 	if (ret)
 		goto err_deinit;
 
+	ret = pci_pwrctrl_create_devices(pci->dev);
+	if (ret)
+		goto err_disable_phy;
+
+	ret = pci_pwrctrl_power_on_devices(pci->dev);
+	if (ret)
+		goto err_pwrctrl_destroy;
+
 	if (pcie->cfg->ops->post_init) {
 		ret = pcie->cfg->ops->post_init(pcie);
 		if (ret)
-			goto err_disable_phy;
+			goto err_pwrctrl_power_off;
 	}
 
 	qcom_pcie_clear_aspm_l0s(pcie->pci);
@@ -1337,6 +1346,11 @@ static int qcom_pcie_host_init(struct dw_pcie_rp *pp)
 
 err_assert_reset:
 	qcom_ep_reset_assert(pcie);
+err_pwrctrl_power_off:
+	pci_pwrctrl_power_off_devices(pci->dev);
+err_pwrctrl_destroy:
+	if (ret != -EPROBE_DEFER)
+		pci_pwrctrl_destroy_devices(pci->dev);
 err_disable_phy:
 	qcom_pcie_phy_power_off(pcie);
 err_deinit:
@@ -1351,6 +1365,11 @@ static void qcom_pcie_host_deinit(struct dw_pcie_rp *pp)
 	struct qcom_pcie *pcie = to_qcom_pcie(pci);
 
 	qcom_ep_reset_assert(pcie);
+	/*
+	 * No need to destroy pwrctrl devices as this function only gets called
+	 * during system suspend as of now.
+	 */
+	pci_pwrctrl_power_off_devices(pci->dev);
 	qcom_pcie_phy_power_off(pcie);
 	pcie->cfg->ops->deinit(pcie);
 }
@@ -2029,7 +2048,7 @@ static int qcom_pcie_probe(struct platform_device *pdev)
 
 	ret = dw_pcie_host_init(pp);
 	if (ret) {
-		dev_err(dev, "cannot initialize host\n");
+		dev_err_probe(dev, ret, "cannot initialize host\n");
 		goto err_phy_exit;
 	}
 
diff --git a/drivers/pci/probe.c b/drivers/pci/probe.c
index 41183aed8f5d..6e7252404b58 100644
--- a/drivers/pci/probe.c
+++ b/drivers/pci/probe.c
@@ -2563,56 +2563,6 @@ bool pci_bus_read_dev_vendor_id(struct pci_bus *bus, int devfn, u32 *l,
 }
 EXPORT_SYMBOL(pci_bus_read_dev_vendor_id);
 
-#if IS_ENABLED(CONFIG_PCI_PWRCTRL)
-static struct platform_device *pci_pwrctrl_create_device(struct pci_bus *bus, int devfn)
-{
-	struct pci_host_bridge *host = pci_find_host_bridge(bus);
-	struct platform_device *pdev;
-	struct device_node *np;
-
-	np = of_pci_find_child_device(dev_of_node(&bus->dev), devfn);
-	if (!np)
-		return NULL;
-
-	pdev = of_find_device_by_node(np);
-	if (pdev) {
-		put_device(&pdev->dev);
-		goto err_put_of_node;
-	}
-
-	/*
-	 * First check whether the pwrctrl device really needs to be created or
-	 * not. This is decided based on at least one of the power supplies
-	 * being defined in the devicetree node of the device.
-	 */
-	if (!of_pci_supply_present(np)) {
-		pr_debug("PCI/pwrctrl: Skipping OF node: %s\n", np->name);
-		goto err_put_of_node;
-	}
-
-	/* Now create the pwrctrl device */
-	pdev = of_platform_device_create(np, NULL, &host->dev);
-	if (!pdev) {
-		pr_err("PCI/pwrctrl: Failed to create pwrctrl device for node: %s\n", np->name);
-		goto err_put_of_node;
-	}
-
-	of_node_put(np);
-
-	return pdev;
-
-err_put_of_node:
-	of_node_put(np);
-
-	return NULL;
-}
-#else
-static struct platform_device *pci_pwrctrl_create_device(struct pci_bus *bus, int devfn)
-{
-	return NULL;
-}
-#endif
-
 /*
  * Read the config data for a PCI device, sanity-check it,
  * and fill in the dev structure.
@@ -2622,15 +2572,6 @@ static struct pci_dev *pci_scan_device(struct pci_bus *bus, int devfn)
 	struct pci_dev *dev;
 	u32 l;
 
-	/*
-	 * Create pwrctrl device (if required) for the PCI device to handle the
-	 * power state. If the pwrctrl device is created, then skip scanning
-	 * further as the pwrctrl core will rescan the bus after powering on
-	 * the device.
-	 */
-	if (pci_pwrctrl_create_device(bus, devfn))
-		return NULL;
-
 	if (!pci_bus_read_dev_vendor_id(bus, devfn, &l, 60*1000))
 		return NULL;
 
diff --git a/drivers/pci/pwrctrl/core.c b/drivers/pci/pwrctrl/core.c
index 0ca448f3bea8..4044edc472b9 100644
--- a/drivers/pci/pwrctrl/core.c
+++ b/drivers/pci/pwrctrl/core.c
@@ -45,16 +45,6 @@ static int pci_pwrctrl_notify(struct notifier_block *nb, unsigned long action,
 	return NOTIFY_DONE;
 }
 
-static void rescan_work_func(struct work_struct *work)
-{
-	struct pci_pwrctrl *pwrctrl = container_of(work,
-						   struct pci_pwrctrl, work);
-
-	pci_lock_rescan_remove();
-	pci_rescan_bus(to_pci_host_bridge(pwrctrl->dev->parent)->bus);
-	pci_unlock_rescan_remove();
-}
-
 /**
  * pci_pwrctrl_init() - Initialize the PCI power control context struct
  *
@@ -64,7 +54,6 @@ static void rescan_work_func(struct work_struct *work)
 void pci_pwrctrl_init(struct pci_pwrctrl *pwrctrl, struct device *dev)
 {
 	pwrctrl->dev = dev;
-	INIT_WORK(&pwrctrl->work, rescan_work_func);
 	dev_set_drvdata(dev, pwrctrl);
 }
 EXPORT_SYMBOL_GPL(pci_pwrctrl_init);
@@ -95,8 +84,6 @@ int pci_pwrctrl_device_set_ready(struct pci_pwrctrl *pwrctrl)
 	if (ret)
 		return ret;
 
-	schedule_work(&pwrctrl->work);
-
 	return 0;
 }
 EXPORT_SYMBOL_GPL(pci_pwrctrl_device_set_ready);
@@ -109,8 +96,6 @@ EXPORT_SYMBOL_GPL(pci_pwrctrl_device_set_ready);
  */
 void pci_pwrctrl_device_unset_ready(struct pci_pwrctrl *pwrctrl)
 {
-	cancel_work_sync(&pwrctrl->work);
-
 	/*
 	 * We don't have to delete the link here. Typically, this function
 	 * is only called when the power control device is being detached. If
diff --git a/drivers/pci/pwrctrl/pci-pwrctrl-pwrseq.c b/drivers/pci/pwrctrl/pci-pwrctrl-pwrseq.c
index 0fb9038a1d18..7697a8a5cdde 100644
--- a/drivers/pci/pwrctrl/pci-pwrctrl-pwrseq.c
+++ b/drivers/pci/pwrctrl/pci-pwrctrl-pwrseq.c
@@ -101,11 +101,6 @@ static int pci_pwrctrl_pwrseq_probe(struct platform_device *pdev)
 		return dev_err_probe(dev, PTR_ERR(data->pwrseq),
 				     "Failed to get the power sequencer\n");
 
-	ret = pci_pwrctrl_pwrseq_power_on(&data->ctx);
-	if (ret)
-		return dev_err_probe(dev, ret,
-				     "Failed to power-on the device\n");
-
 	ret = devm_add_action_or_reset(dev, devm_pci_pwrctrl_pwrseq_power_off,
 				       data);
 	if (ret)
diff --git a/drivers/pci/pwrctrl/pci-pwrctrl-tc9563.c b/drivers/pci/pwrctrl/pci-pwrctrl-tc9563.c
index 0393af2a099c..df77d408adfa 100644
--- a/drivers/pci/pwrctrl/pci-pwrctrl-tc9563.c
+++ b/drivers/pci/pwrctrl/pci-pwrctrl-tc9563.c
@@ -513,8 +513,6 @@ static int tc9563_pwrctrl_power_on(struct pci_pwrctrl *pwrctrl)
 
 static int tc9563_pwrctrl_probe(struct platform_device *pdev)
 {
-	struct pci_host_bridge *bridge = to_pci_host_bridge(pdev->dev.parent);
-	struct pci_bus *bus = bridge->bus;
 	struct device *dev = &pdev->dev;
 	enum tc9563_pwrctrl_ports port;
 	struct tc9563_pwrctrl_ctx *ctx;
@@ -590,22 +588,6 @@ static int tc9563_pwrctrl_probe(struct platform_device *pdev)
 		goto remove_i2c;
 	}
 
-	if (bridge->ops->assert_perst) {
-		ret = bridge->ops->assert_perst(bus, true);
-		if (ret)
-			goto remove_i2c;
-	}
-
-	ret = tc9563_pwrctrl_power_on(&ctx->pwrctrl);
-	if (ret)
-		goto remove_i2c;
-
-	if (bridge->ops->assert_perst) {
-		ret = bridge->ops->assert_perst(bus, false);
-		if (ret)
-			goto power_off;
-	}
-
 	ctx->pwrctrl.power_on = tc9563_pwrctrl_power_on;
 	ctx->pwrctrl.power_off = tc9563_pwrctrl_power_off;
 
@@ -613,8 +595,6 @@ static int tc9563_pwrctrl_probe(struct platform_device *pdev)
 	if (ret)
 		goto power_off;
 
-	platform_set_drvdata(pdev, ctx);
-
 	return 0;
 
 power_off:
@@ -627,7 +607,9 @@ static int tc9563_pwrctrl_probe(struct platform_device *pdev)
 
 static void tc9563_pwrctrl_remove(struct platform_device *pdev)
 {
-	struct tc9563_pwrctrl_ctx *ctx = platform_get_drvdata(pdev);
+	struct pci_pwrctrl *pwrctrl = dev_get_drvdata(&pdev->dev);
+	struct tc9563_pwrctrl_ctx *ctx = container_of(pwrctrl,
+					struct tc9563_pwrctrl_ctx, pwrctrl);
 
 	tc9563_pwrctrl_power_off(&ctx->pwrctrl);
 	i2c_unregister_device(ctx->client);
diff --git a/drivers/pci/pwrctrl/slot.c b/drivers/pci/pwrctrl/slot.c
index 14701f65f1f2..888300aeefec 100644
--- a/drivers/pci/pwrctrl/slot.c
+++ b/drivers/pci/pwrctrl/slot.c
@@ -79,8 +79,6 @@ static int pci_pwrctrl_slot_probe(struct platform_device *pdev)
 		return dev_err_probe(dev, PTR_ERR(slot->clk),
 				     "Failed to enable slot clock\n");
 
-	pci_pwrctrl_slot_power_on(&slot->ctx);
-
 	slot->ctx.power_on = pci_pwrctrl_slot_power_on;
 	slot->ctx.power_off = pci_pwrctrl_slot_power_off;
 
diff --git a/drivers/pci/remove.c b/drivers/pci/remove.c
index 417a9ea59117..e9d519993853 100644
--- a/drivers/pci/remove.c
+++ b/drivers/pci/remove.c
@@ -17,25 +17,6 @@ static void pci_free_resources(struct pci_dev *dev)
 	}
 }
 
-static void pci_pwrctrl_unregister(struct device *dev)
-{
-	struct device_node *np;
-	struct platform_device *pdev;
-
-	np = dev_of_node(dev);
-	if (!np)
-		return;
-
-	pdev = of_find_device_by_node(np);
-	if (!pdev)
-		return;
-
-	of_device_unregister(pdev);
-	put_device(&pdev->dev);
-
-	of_node_clear_flag(np, OF_POPULATED);
-}
-
 static void pci_stop_dev(struct pci_dev *dev)
 {
 	pci_pme_active(dev, false);
@@ -73,7 +54,6 @@ static void pci_destroy_dev(struct pci_dev *dev)
 	pci_ide_destroy(dev);
 	pcie_aspm_exit_link_state(dev);
 	pci_bridge_d3_update(dev);
-	pci_pwrctrl_unregister(&dev->dev);
 	pci_free_resources(dev);
 	put_device(&dev->dev);
 }

-- 
2.48.1

[PATCH v3 6/7] PCI: qcom: Drop the assert_perst() callbacks

[Manivannan Sadhasivam via B4 Relay]

From: Manivannan Sadhasivam <manivannan.sadhasivam@oss.qualcomm.com>

Now that the TC9563 Pwrctrl driver is converted to use the new Pwrctrl
design, there is no need for these assert_perst() callbacks. With the new
design, TC9563 will be powered on before PERST# deassert. So explicit
PERST# handling from the TC9563 driver is not needed.

Hence, drop the callbacks.

Signed-off-by: Manivannan Sadhasivam <manivannan.sadhasivam@oss.qualcomm.com>
---
 drivers/pci/controller/dwc/pcie-designware-host.c |  9 ---------
 drivers/pci/controller/dwc/pcie-designware.h      |  8 --------
 drivers/pci/controller/dwc/pcie-qcom.c            | 13 -------------
 include/linux/pci.h                               |  1 -
 4 files changed, 31 deletions(-)

diff --git a/drivers/pci/controller/dwc/pcie-designware-host.c b/drivers/pci/controller/dwc/pcie-designware-host.c
index 372207c33a85..4862a3a059c7 100644
--- a/drivers/pci/controller/dwc/pcie-designware-host.c
+++ b/drivers/pci/controller/dwc/pcie-designware-host.c
@@ -857,19 +857,10 @@ static void __iomem *dw_pcie_ecam_conf_map_bus(struct pci_bus *bus, unsigned int
 	return pci->dbi_base + where;
 }
 
-static int dw_pcie_op_assert_perst(struct pci_bus *bus, bool assert)
-{
-	struct dw_pcie_rp *pp = bus->sysdata;
-	struct dw_pcie *pci = to_dw_pcie_from_pp(pp);
-
-	return dw_pcie_assert_perst(pci, assert);
-}
-
 static struct pci_ops dw_pcie_ops = {
 	.map_bus = dw_pcie_own_conf_map_bus,
 	.read = pci_generic_config_read,
 	.write = pci_generic_config_write,
-	.assert_perst = dw_pcie_op_assert_perst,
 };
 
 static struct pci_ops dw_pcie_ecam_ops = {
diff --git a/drivers/pci/controller/dwc/pcie-designware.h b/drivers/pci/controller/dwc/pcie-designware.h
index 31685951a080..d24abdb9edaa 100644
--- a/drivers/pci/controller/dwc/pcie-designware.h
+++ b/drivers/pci/controller/dwc/pcie-designware.h
@@ -798,14 +798,6 @@ static inline void dw_pcie_stop_link(struct dw_pcie *pci)
 		pci->ops->stop_link(pci);
 }
 
-static inline int dw_pcie_assert_perst(struct dw_pcie *pci, bool assert)
-{
-	if (pci->ops && pci->ops->assert_perst)
-		return pci->ops->assert_perst(pci, assert);
-
-	return 0;
-}
-
 static inline enum dw_pcie_ltssm dw_pcie_get_ltssm(struct dw_pcie *pci)
 {
 	u32 val;
diff --git a/drivers/pci/controller/dwc/pcie-qcom.c b/drivers/pci/controller/dwc/pcie-qcom.c
index 198befb5be2c..6de3ff555b9d 100644
--- a/drivers/pci/controller/dwc/pcie-qcom.c
+++ b/drivers/pci/controller/dwc/pcie-qcom.c
@@ -650,18 +650,6 @@ static int qcom_pcie_post_init_1_0_0(struct qcom_pcie *pcie)
 	return 0;
 }
 
-static int qcom_pcie_assert_perst(struct dw_pcie *pci, bool assert)
-{
-	struct qcom_pcie *pcie = to_qcom_pcie(pci);
-
-	if (assert)
-		qcom_ep_reset_assert(pcie);
-	else
-		qcom_ep_reset_deassert(pcie);
-
-	return 0;
-}
-
 static void qcom_pcie_2_3_2_ltssm_enable(struct qcom_pcie *pcie)
 {
 	u32 val;
@@ -1523,7 +1511,6 @@ static const struct qcom_pcie_cfg cfg_fw_managed = {
 static const struct dw_pcie_ops dw_pcie_ops = {
 	.link_up = qcom_pcie_link_up,
 	.start_link = qcom_pcie_start_link,
-	.assert_perst = qcom_pcie_assert_perst,
 };
 
 static int qcom_pcie_icc_init(struct qcom_pcie *pcie)
diff --git a/include/linux/pci.h b/include/linux/pci.h
index 864775651c6f..3eb8fd975ad9 100644
--- a/include/linux/pci.h
+++ b/include/linux/pci.h
@@ -854,7 +854,6 @@ struct pci_ops {
 	void __iomem *(*map_bus)(struct pci_bus *bus, unsigned int devfn, int where);
 	int (*read)(struct pci_bus *bus, unsigned int devfn, int where, int size, u32 *val);
 	int (*write)(struct pci_bus *bus, unsigned int devfn, int where, int size, u32 val);
-	int (*assert_perst)(struct pci_bus *bus, bool assert);
 };
 
 /*

-- 
2.48.1

[PATCH v3 7/7] PCI: qcom: Rename PERST# assert/deassert helpers for uniformity

[Manivannan Sadhasivam via B4 Relay]

From: Manivannan Sadhasivam <manivannan.sadhasivam@oss.qualcomm.com>

Rename the PERST# assert/deassert helpers from
qcom_ep_reset_{assert/deassert}() to qcom_pcie_perst_{assert/deassert}() to
maintain uniformity.

Signed-off-by: Manivannan Sadhasivam <manivannan.sadhasivam@oss.qualcomm.com>
---
 drivers/pci/controller/dwc/pcie-qcom.c | 18 +++++++++---------
 1 file changed, 9 insertions(+), 9 deletions(-)

diff --git a/drivers/pci/controller/dwc/pcie-qcom.c b/drivers/pci/controller/dwc/pcie-qcom.c
index 6de3ff555b9d..a9293502e565 100644
--- a/drivers/pci/controller/dwc/pcie-qcom.c
+++ b/drivers/pci/controller/dwc/pcie-qcom.c
@@ -295,7 +295,7 @@ struct qcom_pcie {
 
 #define to_qcom_pcie(x)		dev_get_drvdata((x)->dev)
 
-static void qcom_perst_assert(struct qcom_pcie *pcie, bool assert)
+static void __qcom_pcie_perst_assert(struct qcom_pcie *pcie, bool assert)
 {
 	struct qcom_pcie_perst *perst;
 	struct qcom_pcie_port *port;
@@ -309,16 +309,16 @@ static void qcom_perst_assert(struct qcom_pcie *pcie, bool assert)
 	usleep_range(PERST_DELAY_US, PERST_DELAY_US + 500);
 }
 
-static void qcom_ep_reset_assert(struct qcom_pcie *pcie)
+static void qcom_pcie_perst_assert(struct qcom_pcie *pcie)
 {
-	qcom_perst_assert(pcie, true);
+	__qcom_pcie_perst_assert(pcie, true);
 }
 
-static void qcom_ep_reset_deassert(struct qcom_pcie *pcie)
+static void qcom_pcie_perst_deassert(struct qcom_pcie *pcie)
 {
 	/* Ensure that PERST has been asserted for at least 100 ms */
 	msleep(PCIE_T_PVPERL_MS);
-	qcom_perst_assert(pcie, false);
+	__qcom_pcie_perst_assert(pcie, false);
 }
 
 static int qcom_pcie_start_link(struct dw_pcie *pci)
@@ -1296,7 +1296,7 @@ static int qcom_pcie_host_init(struct dw_pcie_rp *pp)
 	struct qcom_pcie *pcie = to_qcom_pcie(pci);
 	int ret;
 
-	qcom_ep_reset_assert(pcie);
+	qcom_pcie_perst_assert(pcie);
 
 	ret = pcie->cfg->ops->init(pcie);
 	if (ret)
@@ -1322,7 +1322,7 @@ static int qcom_pcie_host_init(struct dw_pcie_rp *pp)
 
 	qcom_pcie_clear_aspm_l0s(pcie->pci);
 
-	qcom_ep_reset_deassert(pcie);
+	qcom_pcie_perst_deassert(pcie);
 
 	if (pcie->cfg->ops->config_sid) {
 		ret = pcie->cfg->ops->config_sid(pcie);
@@ -1333,7 +1333,7 @@ static int qcom_pcie_host_init(struct dw_pcie_rp *pp)
 	return 0;
 
 err_assert_reset:
-	qcom_ep_reset_assert(pcie);
+	qcom_pcie_perst_assert(pcie);
 err_pwrctrl_power_off:
 	pci_pwrctrl_power_off_devices(pci->dev);
 err_pwrctrl_destroy:
@@ -1352,7 +1352,7 @@ static void qcom_pcie_host_deinit(struct dw_pcie_rp *pp)
 	struct dw_pcie *pci = to_dw_pcie_from_pp(pp);
 	struct qcom_pcie *pcie = to_qcom_pcie(pci);
 
-	qcom_ep_reset_assert(pcie);
+	qcom_pcie_perst_assert(pcie);
 	/*
 	 * No need to destroy pwrctrl devices as this function only gets called
 	 * during system suspend as of now.

-- 
2.48.1

Re: [PATCH v3 0/7] PCI/pwrctrl: Major rework to integrate pwrctrl devices with controller drivers

[Niklas Cassel]

On Mon, Dec 29, 2025 at 10:56:51PM +0530, Manivannan Sadhasivam via B4 Relay wrote:
> Hi,
> 
> This series provides a major rework for the PCI power control (pwrctrl)
> framework to enable the pwrctrl devices to be controlled by the PCI controller
> drivers.
> 
> Problem Statement
> =================
> 
> Currently, the pwrctrl framework faces two major issues:
> 
> 1. Missing PERST# integration

AFAICT, and from reading your reply here:

https://lore.kernel.org/linux-pci/ibvk4it7th4bi6djoxshjqjh7zusbulzpndac5jtqkqovvgcei@5sycben7pqkk/

  I suppose maybe you plan to enhance pwrctrl so it can assert/deassert
  individual PERST# in the hierarchy?

"No, that plan has been dropped for good. For now, PERST# will be handled
entirely by the controller drivers. Sharing the PERST# handling with pwrctrl
proved to be a pain and it looks more clean (after the API introduction) to
handle PERST# in controller drivers."

Thus, it seems that even after this series, pwrctrl will be missing PERST#
integration. Perhaps the cover letter could be rephrased to more clearly
highlight this.

Because it seems a bit weird that the first point of the problem statement
(missing PERST# integration) will still be the case after this series.


Kind regards,
Niklas

Re: [PATCH v3 0/7] PCI/pwrctrl: Major rework to integrate pwrctrl devices with controller drivers

[Manivannan Sadhasivam]

On Tue, Dec 30, 2025 at 11:35:55AM +0100, Niklas Cassel wrote:
> On Mon, Dec 29, 2025 at 10:56:51PM +0530, Manivannan Sadhasivam via B4 Relay wrote:
> > Hi,
> > 
> > This series provides a major rework for the PCI power control (pwrctrl)
> > framework to enable the pwrctrl devices to be controlled by the PCI controller
> > drivers.
> > 
> > Problem Statement
> > =================
> > 
> > Currently, the pwrctrl framework faces two major issues:
> > 
> > 1. Missing PERST# integration
> 
> AFAICT, and from reading your reply here:
> 
> https://lore.kernel.org/linux-pci/ibvk4it7th4bi6djoxshjqjh7zusbulzpndac5jtqkqovvgcei@5sycben7pqkk/
> 
>   I suppose maybe you plan to enhance pwrctrl so it can assert/deassert
>   individual PERST# in the hierarchy?
> 
> "No, that plan has been dropped for good. For now, PERST# will be handled
> entirely by the controller drivers. Sharing the PERST# handling with pwrctrl
> proved to be a pain and it looks more clean (after the API introduction) to
> handle PERST# in controller drivers."
> 
> Thus, it seems that even after this series, pwrctrl will be missing PERST#
> integration. Perhaps the cover letter could be rephrased to more clearly
> highlight this.
> 
> Because it seems a bit weird that the first point of the problem statement
> (missing PERST# integration) will still be the case after this series.
> 

Maybe the wording has confused you. I intend to say that the previous
implementation doesn't integrate PERST# properly because controller drivers
deasserted PERST# even before the pwrctrl driver has turned on the power and
both of them worked asynchronously. But with this series they become synchronous
as the controller drivers have the control over the pwrctrl and PERST# and they
can assert/deassert PERST# following the spec timing requirements.

So even though PERST# is not part of the pwrctrl, the integration is now in
place. But I agree that the wording could be improved. I will rephrase it if I
happen to send next version.

- Mani

-- 
மணிவண்ணன் சதாசிவம்

Re: [PATCH v3 0/7] PCI/pwrctrl: Major rework to integrate pwrctrl devices with controller drivers

[Niklas Cassel]

Hello Mani,

On Mon, Dec 29, 2025 at 10:56:51PM +0530, Manivannan Sadhasivam via B4 Relay wrote:
> **NOTE**: With this series, the controller driver may undergo multiple probe
> deferral if the pwrctrl driver was not available during the controller driver
> probe. This is pretty much required to avoid the resource allocation issue. I
> plan to replace probe deferral with blocking wait in the coming days.

It sounds like you want to base that upcoming series on top of this series.

Considering that we are only at -rc3, would it perhaps be a good idea to
wait for you to implement the blocking wait, so that it can be part of
this series, to avoid the additional code churn?


Kind regards,
Niklas

Re: [PATCH v3 6/7] PCI: qcom: Drop the assert_perst() callbacks

[Niklas Cassel]

On Mon, Dec 29, 2025 at 10:56:57PM +0530, Manivannan Sadhasivam via B4 Relay wrote:
> From: Manivannan Sadhasivam <manivannan.sadhasivam@oss.qualcomm.com>
> 
> Now that the TC9563 Pwrctrl driver is converted to use the new Pwrctrl
> design, there is no need for these assert_perst() callbacks. With the new
> design, TC9563 will be powered on before PERST# deassert. So explicit
> PERST# handling from the TC9563 driver is not needed.

The commit message is a little bit confusing IMO.
The explicit PERST# handling in the TC9563 driver was removed in the
previous commit, so perhaps it is better to not mention TC9563 driver
explicitly (all pwrctrl drivers need to stop using the assert_perst(),
that TC9563 was the only pwrctrl driver user of this API is a detail).


Perhaps phrase the commit message something like:
""
Previously, the controller drivers probed first, toggled PERST#, and
enabled link training and scanned the bus. By the time the pwrctrl driver
probe got called, link training was already enabled by the controller driver.

The pwrctrl drivers thus had to call the .assert_perst() callback, to assert
PERST#, power on the needed resources, and then call the .assert_perst()
callback to deassert PERST#.

Now when all pwrctrl drivers have been converted to new pwrctrl design,
there is no need for the .assert_perst() callback in the controller drivers,
because with the new design, the actual work by the pwrctrl driver will have
been done before the controller driver enumerates the bus. There is thus no
longer any need for .assert_perst() callbacks in the controller drivers.
""

Perhaps also split this commit in two.
Because with the "PCI: qcom:" prefix it is not clear that you are also
removing the callbacks from pci.h

So perhaps create a second patch with only "PCI: " prefix:
""
Now when all .assert_callback() implementations have been removed from
the controller drivers, drop the .assert_callback callback from pci.h.
""


Kind regards,
Niklas

Re: [PATCH v3 0/7] PCI/pwrctrl: Major rework to integrate pwrctrl devices with controller drivers

[Manivannan Sadhasivam]

On Tue, Dec 30, 2025 at 12:31:11PM +0100, Niklas Cassel wrote:
> Hello Mani,
> 
> On Mon, Dec 29, 2025 at 10:56:51PM +0530, Manivannan Sadhasivam via B4 Relay wrote:
> > **NOTE**: With this series, the controller driver may undergo multiple probe
> > deferral if the pwrctrl driver was not available during the controller driver
> > probe. This is pretty much required to avoid the resource allocation issue. I
> > plan to replace probe deferral with blocking wait in the coming days.
> 
> It sounds like you want to base that upcoming series on top of this series.
> 
> Considering that we are only at -rc3, would it perhaps be a good idea to
> wait for you to implement the blocking wait, so that it can be part of
> this series, to avoid the additional code churn?
> 

Blocking wait feture is not strictly required for this functionality. It is
something I wanted to implement to avoid multiple probe deferrals, but blocking
wait will also achieve the same by just waiting for all pwrctrl drivers to be
probed instead of returning -EPROBE_DEFER.

But I haven't figured out yet on how to do it though. That's why I sent this
series to allow it to be put into -next and have some test coverage.

If I happen to send the blocking wait patches this cycle itself (should be
atmost 2 patches), those patches could be squashed with this series itself. So
I don't see it as a big churn.

- Mani

-- 
மணிவண்ணன் சதாசிவம்

Re: [PATCH v3 0/7] PCI/pwrctrl: Major rework to integrate pwrctrl devices with controller drivers

[Niklas Cassel]

On Tue, Dec 30, 2025 at 06:03:21PM +0530, Manivannan Sadhasivam wrote:
> On Tue, Dec 30, 2025 at 12:31:11PM +0100, Niklas Cassel wrote:
> 
> If I happen to send the blocking wait patches this cycle itself (should be
> atmost 2 patches), those patches could be squashed with this series itself. So
> I don't see it as a big churn.

Sounds good to me.


Kind regards,
Niklas

Re: [PATCH v3 6/7] PCI: qcom: Drop the assert_perst() callbacks

[Niklas Cassel]

On Tue, Dec 30, 2025 at 01:31:50PM +0100, Niklas Cassel wrote:
> On Mon, Dec 29, 2025 at 10:56:57PM +0530, Manivannan Sadhasivam via B4 Relay wrote:
> 
> Now when all pwrctrl drivers have been converted to new pwrctrl design,
> there is no need for the .assert_perst() callback in the controller drivers,
> because with the new design, the actual work by the pwrctrl driver will have
> been done before the controller driver enumerates the bus. There is thus no
> longer any need for .assert_perst() callbacks in the controller drivers.

s/before the controller driver enumerates the bus/before the controller driver
asserts + desserts PERST# and starts link training/


Kind regards,
Niklas