diff options
Diffstat (limited to 'drivers/pci/pwrctl/core.c')
| -rw-r--r-- | drivers/pci/pwrctl/core.c | 157 |
1 files changed, 157 insertions, 0 deletions
diff --git a/drivers/pci/pwrctl/core.c b/drivers/pci/pwrctl/core.c new file mode 100644 index 000000000000..01d913b60316 --- /dev/null +++ b/drivers/pci/pwrctl/core.c @@ -0,0 +1,157 @@ +// SPDX-License-Identifier: GPL-2.0-only +/* + * Copyright (C) 2024 Linaro Ltd. + */ + +#include <linux/device.h> +#include <linux/export.h> +#include <linux/kernel.h> +#include <linux/pci.h> +#include <linux/pci-pwrctl.h> +#include <linux/property.h> +#include <linux/slab.h> + +static int pci_pwrctl_notify(struct notifier_block *nb, unsigned long action, + void *data) +{ + struct pci_pwrctl *pwrctl = container_of(nb, struct pci_pwrctl, nb); + struct device *dev = data; + + if (dev_fwnode(dev) != dev_fwnode(pwrctl->dev)) + return NOTIFY_DONE; + + switch (action) { + case BUS_NOTIFY_ADD_DEVICE: + /* + * We will have two struct device objects bound to two different + * drivers on different buses but consuming the same DT node. We + * must not bind the pins twice in this case but only once for + * the first device to be added. + * + * If we got here then the PCI device is the second after the + * power control platform device. Mark its OF node as reused. + */ + dev->of_node_reused = true; + break; + case BUS_NOTIFY_BOUND_DRIVER: + pwrctl->link = device_link_add(dev, pwrctl->dev, + DL_FLAG_AUTOREMOVE_CONSUMER); + if (!pwrctl->link) + dev_err(pwrctl->dev, "Failed to add device link\n"); + break; + case BUS_NOTIFY_UNBOUND_DRIVER: + if (pwrctl->link) + device_link_remove(dev, pwrctl->dev); + break; + } + + return NOTIFY_DONE; +} + +static void rescan_work_func(struct work_struct *work) +{ + struct pci_pwrctl *pwrctl = container_of(work, struct pci_pwrctl, work); + + pci_lock_rescan_remove(); + pci_rescan_bus(to_pci_dev(pwrctl->dev->parent)->bus); + pci_unlock_rescan_remove(); +} + +/** + * pci_pwrctl_init() - Initialize the PCI power control context struct + * + * @pwrctl: PCI power control data + * @dev: Parent device + */ +void pci_pwrctl_init(struct pci_pwrctl *pwrctl, struct device *dev) +{ + pwrctl->dev = dev; + INIT_WORK(&pwrctl->work, rescan_work_func); +} +EXPORT_SYMBOL_GPL(pci_pwrctl_init); + +/** + * pci_pwrctl_device_set_ready() - Notify the pwrctl subsystem that the PCI + * device is powered-up and ready to be detected. + * + * @pwrctl: PCI power control data. + * + * Returns: + * 0 on success, negative error number on error. + * + * Note: + * This function returning 0 doesn't mean the device was detected. It means, + * that the bus rescan was successfully started. The device will get bound to + * its PCI driver asynchronously. + */ +int pci_pwrctl_device_set_ready(struct pci_pwrctl *pwrctl) +{ + int ret; + + if (!pwrctl->dev) + return -ENODEV; + + pwrctl->nb.notifier_call = pci_pwrctl_notify; + ret = bus_register_notifier(&pci_bus_type, &pwrctl->nb); + if (ret) + return ret; + + schedule_work(&pwrctl->work); + + return 0; +} +EXPORT_SYMBOL_GPL(pci_pwrctl_device_set_ready); + +/** + * pci_pwrctl_device_unset_ready() - Notify the pwrctl subsystem that the PCI + * device is about to be powered-down. + * + * @pwrctl: PCI power control data. + */ +void pci_pwrctl_device_unset_ready(struct pci_pwrctl *pwrctl) +{ + /* + * We don't have to delete the link here. Typically, this function + * is only called when the power control device is being detached. If + * it is being detached then the child PCI device must have already + * been unbound too or the device core wouldn't let us unbind. + */ + bus_unregister_notifier(&pci_bus_type, &pwrctl->nb); +} +EXPORT_SYMBOL_GPL(pci_pwrctl_device_unset_ready); + +static void devm_pci_pwrctl_device_unset_ready(void *data) +{ + struct pci_pwrctl *pwrctl = data; + + pci_pwrctl_device_unset_ready(pwrctl); +} + +/** + * devm_pci_pwrctl_device_set_ready - Managed variant of + * pci_pwrctl_device_set_ready(). + * + * @dev: Device managing this pwrctl provider. + * @pwrctl: PCI power control data. + * + * Returns: + * 0 on success, negative error number on error. + */ +int devm_pci_pwrctl_device_set_ready(struct device *dev, + struct pci_pwrctl *pwrctl) +{ + int ret; + + ret = pci_pwrctl_device_set_ready(pwrctl); + if (ret) + return ret; + + return devm_add_action_or_reset(dev, + devm_pci_pwrctl_device_unset_ready, + pwrctl); +} +EXPORT_SYMBOL_GPL(devm_pci_pwrctl_device_set_ready); + +MODULE_AUTHOR("Bartosz Golaszewski <bartosz.golaszewski@linaro.org>"); +MODULE_DESCRIPTION("PCI Device Power Control core driver"); +MODULE_LICENSE("GPL"); |