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Message-ID: <CAMRc=McH9u7Y8EZMwSjcCUs6rVx9K+h5OxFOrjwXhKm1td-EeQ@mail.gmail.com>
Date: Thu, 27 Nov 2025 06:37:53 -0800
From: Bartosz Golaszewski <brgl@...ev.pl>
To: manivannan.sadhasivam@....qualcomm.com
Cc: Manivannan Sadhasivam via B4 Relay <devnull+manivannan.sadhasivam.oss.qualcomm.com@...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>, 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>
Subject: Re: [PATCH v2 10/10] power: sequencing: pcie-m2: Add support for PCIe
M.2 Key E connectors
On Tue, 25 Nov 2025 15:45:14 +0100, Manivannan Sadhasivam via B4 Relay
<devnull+manivannan.sadhasivam.oss.qualcomm.com@...nel.org> said:
> From: Manivannan Sadhasivam <manivannan.sadhasivam@....qualcomm.com>
>
> Add support for handling the power sequence of the PCIe M.2 Key E
> connectors. These connectors are used to attach the Wireless Connectivity
> devices to the host machine including combinations of WiFi, BT, NFC using
> interfaces such as PCIe/SDIO for WiFi, USB/UART for BT and I2C for NFC.
>
> Currently, this driver supports only the PCIe interface for WiFi and UART
> interface for BT. The driver also only supports driving the 3.3v/1.8v power
> supplies and W_DISABLE{1/2}# GPIOs. The optional signals of the Key E
> connectors are not currently supported.
>
> For supporting Bluetooth over the non-discoverable UART interface, the
> driver currently creates the serdev interface 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.
>
> Signed-off-by: Manivannan Sadhasivam <manivannan.sadhasivam@....qualcomm.com>
> ---
> drivers/power/sequencing/Kconfig | 1 +
> drivers/power/sequencing/pwrseq-pcie-m2.c | 205 +++++++++++++++++++++++++++++-
> 2 files changed, 199 insertions(+), 7 deletions(-)
>
> diff --git a/drivers/power/sequencing/Kconfig b/drivers/power/sequencing/Kconfig
> index f5fff84566ba..29bd204319cc 100644
> --- a/drivers/power/sequencing/Kconfig
> +++ b/drivers/power/sequencing/Kconfig
> @@ -38,6 +38,7 @@ config POWER_SEQUENCING_TH1520_GPU
> config POWER_SEQUENCING_PCIE_M2
> tristate "PCIe M.2 connector power sequencing driver"
> depends on OF || COMPILE_TEST
> + depends on PCI
> help
> Say Y here to enable the power sequencing driver for PCIe M.2
> connectors. This driver handles the power sequencing for the M.2
> diff --git a/drivers/power/sequencing/pwrseq-pcie-m2.c b/drivers/power/sequencing/pwrseq-pcie-m2.c
> index 4835d099d967..c2cc129f6917 100644
> --- a/drivers/power/sequencing/pwrseq-pcie-m2.c
> +++ b/drivers/power/sequencing/pwrseq-pcie-m2.c
> @@ -5,14 +5,17 @@
> */
>
I think you're missing linux/err.h here.
> #include <linux/device.h>
> +#include <linux/gpio/consumer.h>
> #include <linux/mod_devicetable.h>
> #include <linux/module.h>
> #include <linux/of.h>
> #include <linux/of_graph.h>
> #include <linux/of_platform.h>
> +#include <linux/pci.h>
> #include <linux/platform_device.h>
> #include <linux/pwrseq/provider.h>
> #include <linux/regulator/consumer.h>
> +#include <linux/serdev.h>
> #include <linux/slab.h>
(snip)
>
> +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 device_node *pci_remote __free(device_node) = NULL;
> + struct device_node *serdev_remote __free(device_node) = NULL;
> + struct serdev_controller *serdev_ctrl;
> + struct serdev_device *serdev;
> + struct device *dev = ctx->dev;
> + 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_remote = of_graph_get_remote_node(dev_of_node(ctx->dev), 0, 0);
> + if (!pci_remote || (pci_remote != pdev->dev.parent->of_node))
> + return NOTIFY_DONE;
> +
> + switch (action) {
> + case BUS_NOTIFY_ADD_DEVICE:
> + /* Create serdev device for WCN7850 */
> + if (pdev->vendor == PCI_VENDOR_ID_QCOM && pdev->device == 0x1107) {
> + serdev_remote = of_graph_get_remote_node(dev_of_node(ctx->dev), 1, 1);
> + if (!serdev_remote)
> + return NOTIFY_DONE;
> +
> + serdev_ctrl = of_find_serdev_controller_by_node(serdev_remote);
> + if (!serdev_ctrl)
> + return NOTIFY_DONE;
> +
> + serdev = serdev_device_alloc(serdev_ctrl);
> + if (!serdev)
> + return NOTIFY_BAD;
> +
This is where you'd add the software node I wrote about under another patch
from this series.
> + ret = serdev_device_add(serdev, "WCN7850");
> + if (ret) {
> + dev_err(dev, "Failed to add serdev for WCN7850: %d\n", ret);
> + serdev_device_put(serdev);
If you're touching serdev code in the same series, maybe you could define
a cleanup action for serdev devices and use it here?
> + return NOTIFY_BAD;
> + }
> + }
> + break;
> + }
> +
> + return NOTIFY_OK;
> +}
> +
> +static bool pwrseq_pcie_m2_check_remote_node(struct device *dev, u8 port, u8 endpoint,
> + const char *node)
> +{
> + struct device_node *remote __free(device_node) = NULL;
> +
> + remote = of_graph_get_remote_node(dev_of_node(dev), port, endpoint);
I'd do it like this to follow the convention of initializing automatic
variables at definition.
struct device_node *remote __free(device_node) =
of_graph_get_remote_node(dev_of_node(dev), port, endpoint);
> + if (remote && of_node_name_eq(remote, node))
> + return true;
> +
> + return false;
> +}
> +
> +/*
> + * If the connector exposes a non-discoverable bus like UART, the respective
> + * protocol device needs to be created manually with the help of the notifier
> + * of the discoverable bus like PCIe.
> + */
> +static int pwrseq_pcie_m2_register_notifier(struct pwrseq_pcie_m2_ctx *ctx, struct device *dev)
> +{
> + int ret;
> +
> + /*
> + * Register a PCI notifier for Key E connector that has PCIe as Port
> + * 0/Endpoint 0 interface and Serial as Port 1/Endpoint 1 interface.
> + */
> + if (pwrseq_pcie_m2_check_remote_node(dev, 1, 1, "serial")) {
> + if (pwrseq_pcie_m2_check_remote_node(dev, 0, 0, "pcie")) {
> + ctx->dev = dev;
> + ctx->nb.notifier_call = pwrseq_m2_pcie_notify;
> + ret = bus_register_notifier(&pci_bus_type, &ctx->nb);
> + if (ret) {
> + dev_err_probe(dev, ret, "Failed to register notifier for serdev\n");
> + return ret;
> + }
return dev_err_probe() and save three lines?
> + }
> + }
> +
> + return 0;
> +}
> +
Bart
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