linux-kernel - Re: [PATCH v4 9/9] power: sequencing: pcie-m2: Create serdev device for WCN7850 bluetooth

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Message-ID: <aWVJ_ncUkAYswE3W@smile.fi.intel.com>
Date: Mon, 12 Jan 2026 21:22:38 +0200
From: Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
To: manivannan.sadhasivam@....qualcomm.com
Cc: Rob Herring <robh@...nel.org>,
	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	Jiri Slaby <jirislaby@...nel.org>,
	Nathan Chancellor <nathan@...nel.org>,
	Nicolas Schier <nicolas.schier@...ux.dev>,
	Hans de Goede <hansg@...nel.org>,
	Ilpo Järvinen <ilpo.jarvinen@...ux.intel.com>,
	Mark Pearson <mpearson-lenovo@...ebb.ca>,
	"Derek J. Clark" <derekjohn.clark@...il.com>,
	Manivannan Sadhasivam <mani@...nel.org>,
	Krzysztof Kozlowski <krzk+dt@...nel.org>,
	Conor Dooley <conor+dt@...nel.org>,
	Marcel Holtmann <marcel@...tmann.org>,
	Luiz Augusto von Dentz <luiz.dentz@...il.com>,
	Bartosz Golaszewski <brgl@...ev.pl>,
	Bartosz Golaszewski <brgl@...nel.org>, linux-serial@...r.kernel.org,
	linux-kernel@...r.kernel.org, linux-kbuild@...r.kernel.org,
	platform-driver-x86@...r.kernel.org, linux-pci@...r.kernel.org,
	devicetree@...r.kernel.org, linux-arm-msm@...r.kernel.org,
	linux-bluetooth@...r.kernel.org, linux-pm@...r.kernel.org,
	Stephan Gerhold <stephan.gerhold@...aro.org>,
	Dmitry Baryshkov <dmitry.baryshkov@....qualcomm.com>,
	linux-acpi@...r.kernel.org
Subject: Re: [PATCH v4 9/9] power: sequencing: pcie-m2: Create serdev device
 for WCN7850 bluetooth

On Mon, Jan 12, 2026 at 09:56:08PM +0530, Manivannan Sadhasivam via B4 Relay wrote:

> For supporting bluetooth over the non-discoverable UART interface of
> WCN7850, create the serdev device after enumerating the PCIe interface.
> This is mandatory since the device ID is only known after the PCIe
> enumeration and the ID is used for creating the serdev device.
> 
> Since by default there is no OF or ACPI node for the created serdev,
> create a dynamic OF 'bluetooth' node with the 'compatible' property and
> attach it to the serdev device. This will allow the serdev device to bind
> to the existing bluetooth driver.

...

> +static int pwrseq_m2_pcie_notify(struct notifier_block *nb, unsigned long action,
> +			      void *data)
> +{
> +	struct pwrseq_pcie_m2_ctx *ctx = container_of(nb, struct pwrseq_pcie_m2_ctx, nb);
> +	struct pci_dev *pdev = to_pci_dev(data);
> +	struct serdev_controller *serdev_ctrl;
> +	struct device *dev = ctx->dev;
> +	struct device_node *pci_parent;
> +	int ret;
> +
> +	/*
> +	 * Check whether the PCI device is associated with this M.2 connector or
> +	 * not, by comparing the OF node of the PCI device parent and the Port 0
> +	 * (PCIe) remote node parent OF node.
> +	 */
> +	pci_parent = of_graph_get_remote_node(dev_of_node(ctx->dev), 0, 0);

> +	if (!pci_parent || (pci_parent != pdev->dev.parent->of_node)) {

!device_match_of_node()

> +		of_node_put(pci_parent);
> +		return NOTIFY_DONE;
> +	}
> +	of_node_put(pci_parent);
> +
> +	switch (action) {
> +	case BUS_NOTIFY_ADD_DEVICE:
> +		/* Create serdev device for WCN7850 */
> +		if (pdev->vendor == PCI_VENDOR_ID_QCOM && pdev->device == 0x1107) {
> +			struct device_node *serdev_parent __free(device_node) =
> +				of_graph_get_remote_node(dev_of_node(ctx->dev), 1, 1);
> +			if (!serdev_parent)
> +				return NOTIFY_DONE;
> +
> +			serdev_ctrl = of_find_serdev_controller_by_node(serdev_parent);
> +			if (!serdev_ctrl)
> +				return NOTIFY_DONE;
> +
> +			ctx->serdev = serdev_device_alloc(serdev_ctrl);
> +			if (!ctx->serdev)
> +				return NOTIFY_BAD;
> +
> +			ret = pwrseq_m2_pcie_create_bt_node(ctx, serdev_parent);
> +			if (ret) {
> +				serdev_device_put(ctx->serdev);
> +				return notifier_from_errno(ret);
> +			}
> +
> +			ret = serdev_device_add(ctx->serdev);
> +			if (ret) {
> +				dev_err(dev, "Failed to add serdev for WCN7850: %d\n", ret);
> +				of_changeset_revert(ctx->ocs);
> +				of_changeset_destroy(ctx->ocs);
> +				serdev_device_put(ctx->serdev);
> +				return notifier_from_errno(ret);
> +			}
> +		}
> +		break;
> +	case BUS_NOTIFY_REMOVED_DEVICE:
> +		/* Destroy serdev device for WCN7850 */
> +		if (pdev->vendor == PCI_VENDOR_ID_QCOM && pdev->device == 0x1107) {
> +			serdev_device_remove(ctx->serdev);
> +			of_changeset_revert(ctx->ocs);
> +			of_changeset_destroy(ctx->ocs);
> +		}
> +		break;
> +	}
> +
> +	return NOTIFY_OK;
> +}

-- 
With Best Regards,
Andy Shevchenko