@@ -296,5 +296,6 @@ source "drivers/pci/hotplug/Kconfig"
source "drivers/pci/controller/Kconfig"
source "drivers/pci/endpoint/Kconfig"
source "drivers/pci/switch/Kconfig"
+source "drivers/pci/pwrctl/Kconfig"
endif
@@ -9,6 +9,7 @@ obj-$(CONFIG_PCI) += access.o bus.o probe.o host-bridge.o \
obj-$(CONFIG_PCI) += msi/
obj-$(CONFIG_PCI) += pcie/
+obj-$(CONFIG_PCI) += pwrctl/
ifdef CONFIG_PCI
obj-$(CONFIG_PROC_FS) += proc.o
new file mode 100644
@@ -0,0 +1,8 @@
+# SPDX-License-Identifier: GPL-2.0-only
+
+menu "PCI Power control drivers"
+
+config PCI_PWRCTL
+ tristate
+
+endmenu
new file mode 100644
@@ -0,0 +1,4 @@
+# SPDX-License-Identifier: GPL-2.0-only
+
+obj-$(CONFIG_PCI_PWRCTL) += pci-pwrctl-core.o
+pci-pwrctl-core-y := core.o
new file mode 100644
@@ -0,0 +1,136 @@
+// 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_del(pwrctl->link);
+ break;
+ }
+
+ return NOTIFY_DONE;
+}
+
+/**
+ * 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;
+
+ pci_lock_rescan_remove();
+ pci_rescan_bus(to_pci_dev(pwrctl->dev->parent)->bus);
+ pci_unlock_rescan_remove();
+
+ 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_set_ready(pwrctl);
+}
+
+/**
+ * devm_pci_pwrctl_device_set_ready - Managed variant of
+ * pci_pwrctl_device_set_ready().
+ *
+ * @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");
new file mode 100644
@@ -0,0 +1,51 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+/*
+ * Copyright (C) 2024 Linaro Ltd.
+ */
+
+#ifndef __PCI_PWRCTL_H__
+#define __PCI_PWRCTL_H__
+
+#include <linux/notifier.h>
+
+struct device;
+struct device_link;
+
+/*
+ * This is a simple framework for solving the issue of PCI devices that require
+ * certain resources (regulators, GPIOs, clocks) to be enabled before the
+ * device can actually be detected on the PCI bus.
+ *
+ * The idea is to reuse the platform bus to populate OF nodes describing the
+ * PCI device and its resources, let these platform devices probe and enable
+ * relevant resources and then trigger a rescan of the PCI bus allowing for the
+ * same device (with a second associated struct device) to be registered with
+ * the PCI subsystem.
+ *
+ * To preserve a correct hierarchy for PCI power management and device reset,
+ * we create a device link between the power control platform device (parent)
+ * and the supplied PCI device (child).
+ */
+
+/**
+ * struct pci_pwrctl - PCI device power control context.
+ * @dev - Address of the power controlling device.
+ *
+ * An object of this type must be allocated by the PCI power control device and
+ * passed to the pwrctl subsystem to trigger a bus rescan and setup a device
+ * link with the device once it's up.
+ */
+struct pci_pwrctl {
+ struct device *dev;
+
+ /* Private, don't use. */
+ struct notifier_block nb;
+ struct device_link *link;
+};
+
+int pci_pwrctl_device_set_ready(struct pci_pwrctl *pwrctl);
+void pci_pwrctl_device_unset_ready(struct pci_pwrctl *pwrctl);
+int devm_pci_pwrctl_device_set_ready(struct device *dev,
+ struct pci_pwrctl *pwrctl);
+
+#endif /* __PCI_PWRCTL_H__ */