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Some PCI devices must be powered-on before they can be detected on the bus. Introduce a simple framework reusing the existing PCI OF infrastructure. The way this works is: a DT node representing a PCI device connected to the port can be matched against its power control platform driver. If the match succeeds, the driver is responsible for powering-up the device and calling pci_pwrctl_device_set_ready() which will trigger a PCI bus rescan as well as subscribe to PCI bus notifications. When the device is detected and created, we'll make it consume the same DT node that the platform device did. When the device is bound, we'll create a device link between it and the parent power control device. Tested-by: Amit Pundir <amit.pundir@linaro.org> Tested-by: Neil Armstrong <neil.armstrong@linaro.org> # on SM8550-QRD, SM8650-QRD & SM8650-HDK Tested-by: Caleb Connolly <caleb.connolly@linaro.org> # OnePlus 8T Acked-by: Bjorn Helgaas <bhelgaas@google.com> Link: https://lore.kernel.org/r/20240612082019.19161-5-brgl@bgdev.pl Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
138 lines
3.6 KiB
C
138 lines
3.6 KiB
C
// SPDX-License-Identifier: GPL-2.0-only
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/*
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* Copyright (C) 2024 Linaro Ltd.
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*/
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#include <linux/device.h>
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#include <linux/export.h>
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#include <linux/kernel.h>
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#include <linux/pci.h>
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#include <linux/pci-pwrctl.h>
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#include <linux/property.h>
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#include <linux/slab.h>
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static int pci_pwrctl_notify(struct notifier_block *nb, unsigned long action,
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void *data)
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{
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struct pci_pwrctl *pwrctl = container_of(nb, struct pci_pwrctl, nb);
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struct device *dev = data;
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if (dev_fwnode(dev) != dev_fwnode(pwrctl->dev))
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return NOTIFY_DONE;
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switch (action) {
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case BUS_NOTIFY_ADD_DEVICE:
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/*
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* We will have two struct device objects bound to two different
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* drivers on different buses but consuming the same DT node. We
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* must not bind the pins twice in this case but only once for
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* the first device to be added.
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*
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* If we got here then the PCI device is the second after the
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* power control platform device. Mark its OF node as reused.
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*/
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dev->of_node_reused = true;
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break;
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case BUS_NOTIFY_BOUND_DRIVER:
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pwrctl->link = device_link_add(dev, pwrctl->dev,
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DL_FLAG_AUTOREMOVE_CONSUMER);
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if (!pwrctl->link)
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dev_err(pwrctl->dev, "Failed to add device link\n");
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break;
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case BUS_NOTIFY_UNBOUND_DRIVER:
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if (pwrctl->link)
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device_link_remove(dev, pwrctl->dev);
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break;
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}
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return NOTIFY_DONE;
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}
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/**
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* pci_pwrctl_device_set_ready() - Notify the pwrctl subsystem that the PCI
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* device is powered-up and ready to be detected.
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*
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* @pwrctl: PCI power control data.
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*
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* Returns:
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* 0 on success, negative error number on error.
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*
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* Note:
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* This function returning 0 doesn't mean the device was detected. It means,
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* that the bus rescan was successfully started. The device will get bound to
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* its PCI driver asynchronously.
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*/
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int pci_pwrctl_device_set_ready(struct pci_pwrctl *pwrctl)
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{
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int ret;
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if (!pwrctl->dev)
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return -ENODEV;
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pwrctl->nb.notifier_call = pci_pwrctl_notify;
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ret = bus_register_notifier(&pci_bus_type, &pwrctl->nb);
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if (ret)
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return ret;
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pci_lock_rescan_remove();
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pci_rescan_bus(to_pci_dev(pwrctl->dev->parent)->bus);
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pci_unlock_rescan_remove();
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return 0;
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}
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EXPORT_SYMBOL_GPL(pci_pwrctl_device_set_ready);
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/**
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* pci_pwrctl_device_unset_ready() - Notify the pwrctl subsystem that the PCI
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* device is about to be powered-down.
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*
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* @pwrctl: PCI power control data.
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*/
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void pci_pwrctl_device_unset_ready(struct pci_pwrctl *pwrctl)
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{
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/*
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* We don't have to delete the link here. Typically, this function
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* is only called when the power control device is being detached. If
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* it is being detached then the child PCI device must have already
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* been unbound too or the device core wouldn't let us unbind.
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*/
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bus_unregister_notifier(&pci_bus_type, &pwrctl->nb);
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}
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EXPORT_SYMBOL_GPL(pci_pwrctl_device_unset_ready);
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static void devm_pci_pwrctl_device_unset_ready(void *data)
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{
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struct pci_pwrctl *pwrctl = data;
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pci_pwrctl_device_unset_ready(pwrctl);
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}
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/**
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* devm_pci_pwrctl_device_set_ready - Managed variant of
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* pci_pwrctl_device_set_ready().
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*
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* @dev: Device managing this pwrctl provider.
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* @pwrctl: PCI power control data.
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*
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* Returns:
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* 0 on success, negative error number on error.
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*/
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int devm_pci_pwrctl_device_set_ready(struct device *dev,
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struct pci_pwrctl *pwrctl)
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{
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int ret;
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ret = pci_pwrctl_device_set_ready(pwrctl);
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if (ret)
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return ret;
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return devm_add_action_or_reset(dev,
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devm_pci_pwrctl_device_unset_ready,
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pwrctl);
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}
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EXPORT_SYMBOL_GPL(devm_pci_pwrctl_device_set_ready);
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MODULE_AUTHOR("Bartosz Golaszewski <bartosz.golaszewski@linaro.org>");
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MODULE_DESCRIPTION("PCI Device Power Control core driver");
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MODULE_LICENSE("GPL");
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