1 files changed, 148 insertions, 0 deletions

diff --git a/drivers/pci/pwrctrl/core.c b/drivers/pci/pwrctrl/core.c
new file mode 100644
index 000000000000..2fb174db91e5
--- /dev/null
+++ b/drivers/pci/pwrctrl/core.c
@@ -0,0 +1,148 @@
+// 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-pwrctrl.h>
+#include <linux/property.h>
+#include <linux/slab.h>
+
+static int pci_pwrctrl_notify(struct notifier_block *nb, unsigned long action,
+			      void *data)
+{
+	struct pci_pwrctrl *pwrctrl = container_of(nb, struct pci_pwrctrl, nb);
+	struct device *dev = data;
+
+	if (dev_fwnode(dev) != dev_fwnode(pwrctrl->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;
+	}
+
+	return NOTIFY_DONE;
+}
+
+static void rescan_work_func(struct work_struct *work)
+{
+	struct pci_pwrctrl *pwrctrl = container_of(work,
+						   struct pci_pwrctrl, work);
+
+	pci_lock_rescan_remove();
+	pci_rescan_bus(to_pci_dev(pwrctrl->dev->parent)->bus);
+	pci_unlock_rescan_remove();
+}
+
+/**
+ * pci_pwrctrl_init() - Initialize the PCI power control context struct
+ *
+ * @pwrctrl: PCI power control data
+ * @dev: Parent device
+ */
+void pci_pwrctrl_init(struct pci_pwrctrl *pwrctrl, struct device *dev)
+{
+	pwrctrl->dev = dev;
+	INIT_WORK(&pwrctrl->work, rescan_work_func);
+}
+EXPORT_SYMBOL_GPL(pci_pwrctrl_init);
+
+/**
+ * pci_pwrctrl_device_set_ready() - Notify the pwrctrl subsystem that the PCI
+ * device is powered-up and ready to be detected.
+ *
+ * @pwrctrl: 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_pwrctrl_device_set_ready(struct pci_pwrctrl *pwrctrl)
+{
+	int ret;
+
+	if (!pwrctrl->dev)
+		return -ENODEV;
+
+	pwrctrl->nb.notifier_call = pci_pwrctrl_notify;
+	ret = bus_register_notifier(&pci_bus_type, &pwrctrl->nb);
+	if (ret)
+		return ret;
+
+	schedule_work(&pwrctrl->work);
+
+	return 0;
+}
+EXPORT_SYMBOL_GPL(pci_pwrctrl_device_set_ready);
+
+/**
+ * pci_pwrctrl_device_unset_ready() - Notify the pwrctrl subsystem that the PCI
+ * device is about to be powered-down.
+ *
+ * @pwrctrl: PCI power control data.
+ */
+void pci_pwrctrl_device_unset_ready(struct pci_pwrctrl *pwrctrl)
+{
+	/*
+	 * 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, &pwrctrl->nb);
+}
+EXPORT_SYMBOL_GPL(pci_pwrctrl_device_unset_ready);
+
+static void devm_pci_pwrctrl_device_unset_ready(void *data)
+{
+	struct pci_pwrctrl *pwrctrl = data;
+
+	pci_pwrctrl_device_unset_ready(pwrctrl);
+}
+
+/**
+ * devm_pci_pwrctrl_device_set_ready - Managed variant of
+ * pci_pwrctrl_device_set_ready().
+ *
+ * @dev: Device managing this pwrctrl provider.
+ * @pwrctrl: PCI power control data.
+ *
+ * Returns:
+ * 0 on success, negative error number on error.
+ */
+int devm_pci_pwrctrl_device_set_ready(struct device *dev,
+				      struct pci_pwrctrl *pwrctrl)
+{
+	int ret;
+
+	ret = pci_pwrctrl_device_set_ready(pwrctrl);
+	if (ret)
+		return ret;
+
+	return devm_add_action_or_reset(dev,
+					devm_pci_pwrctrl_device_unset_ready,
+					pwrctrl);
+}
+EXPORT_SYMBOL_GPL(devm_pci_pwrctrl_device_set_ready);
+
+MODULE_AUTHOR("Bartosz Golaszewski <bartosz.golaszewski@linaro.org>");
+MODULE_DESCRIPTION("PCI Device Power Control core driver");
+MODULE_LICENSE("GPL");