@@ -5,6 +5,8 @@ source "drivers/amba/Kconfig"
source "drivers/base/Kconfig"
+source "drivers/boot_constraint/Kconfig"
+
source "drivers/bus/Kconfig"
source "drivers/connector/Kconfig"
@@ -73,6 +73,7 @@ obj-$(CONFIG_FB_INTEL) += video/fbdev/intelfb/
obj-$(CONFIG_PARPORT) += parport/
obj-$(CONFIG_NVM) += lightnvm/
obj-y += base/ block/ misc/ mfd/ nfc/
+obj-$(CONFIG_DEV_BOOT_CONSTRAINT) += boot_constraint/
obj-$(CONFIG_LIBNVDIMM) += nvdimm/
obj-$(CONFIG_DAX) += dax/
obj-$(CONFIG_DMA_SHARED_BUFFER) += dma-buf/
@@ -16,6 +16,7 @@
* Copyright (c) 2007-2009 Novell Inc.
*/
+#include <linux/boot_constraint.h>
#include <linux/device.h>
#include <linux/delay.h>
#include <linux/dma-mapping.h>
@@ -419,15 +420,20 @@ static int really_probe(struct device *dev, struct device_driver *drv)
*/
devices_kset_move_last(dev);
- if (dev->bus->probe) {
+ if (dev->bus->probe)
ret = dev->bus->probe(dev);
- if (ret)
- goto probe_failed;
- } else if (drv->probe) {
+ else if (drv->probe)
ret = drv->probe(dev);
- if (ret)
- goto probe_failed;
- }
+
+ /*
+ * Remove boot constraints for both successful and unsuccessful probe(),
+ * except for the case where EPROBE_DEFER is returned by probe().
+ */
+ if (ret != -EPROBE_DEFER)
+ dev_boot_constraints_remove(dev);
+
+ if (ret)
+ goto probe_failed;
if (test_remove) {
test_remove = false;
new file mode 100644
@@ -0,0 +1,9 @@
+config DEV_BOOT_CONSTRAINT
+ bool "Boot constraints for devices"
+ help
+ This enables boot constraints detection for devices. These constraints
+ are (normally) set by the Bootloader and must be satisfied by the
+ kernel until the relevant device driver is probed. Once the driver is
+ probed, the constraint is dropped.
+
+ If unsure, say N.
new file mode 100644
@@ -0,0 +1,3 @@
+# Makefile for device boot constraints
+
+obj-y := core.o
new file mode 100644
@@ -0,0 +1,219 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * This takes care of boot time device constraints, normally set by the
+ * Bootloader.
+ *
+ * Copyright (C) 2017 Linaro.
+ * Viresh Kumar <viresh.kumar@linaro.org>
+ */
+
+#include <linux/err.h>
+#include <linux/export.h>
+#include <linux/mutex.h>
+#include <linux/slab.h>
+
+#include "core.h"
+
+#define for_each_constraint(_constraint, _temp, _cdev) \
+ list_for_each_entry_safe(_constraint, _temp, &_cdev->constraints, node)
+
+/* Global list of all constraint devices currently registered */
+static LIST_HEAD(constraint_devices);
+static DEFINE_MUTEX(constraint_devices_mutex);
+
+/* Boot constraints core */
+
+static struct constraint_dev *constraint_device_find(struct device *dev)
+{
+ struct constraint_dev *cdev;
+
+ list_for_each_entry(cdev, &constraint_devices, node) {
+ if (cdev->dev == dev)
+ return cdev;
+ }
+
+ return NULL;
+}
+
+static struct constraint_dev *constraint_device_allocate(struct device *dev)
+{
+ struct constraint_dev *cdev;
+
+ cdev = kzalloc(sizeof(*cdev), GFP_KERNEL);
+ if (!cdev)
+ return ERR_PTR(-ENOMEM);
+
+ cdev->dev = dev;
+ INIT_LIST_HEAD(&cdev->node);
+ INIT_LIST_HEAD(&cdev->constraints);
+
+ list_add(&cdev->node, &constraint_devices);
+
+ return cdev;
+}
+
+static void constraint_device_free(struct constraint_dev *cdev)
+{
+ list_del(&cdev->node);
+ kfree(cdev);
+}
+
+static struct constraint_dev *constraint_device_get(struct device *dev)
+{
+ struct constraint_dev *cdev;
+
+ cdev = constraint_device_find(dev);
+ if (cdev)
+ return cdev;
+
+ cdev = constraint_device_allocate(dev);
+ if (IS_ERR(cdev)) {
+ dev_err(dev, "Failed to add constraint dev (%ld)\n",
+ PTR_ERR(cdev));
+ }
+
+ return cdev;
+}
+
+static void constraint_device_put(struct constraint_dev *cdev)
+{
+ if (!list_empty(&cdev->constraints))
+ return;
+
+ constraint_device_free(cdev);
+}
+
+static struct constraint *constraint_allocate(struct constraint_dev *cdev,
+ enum dev_boot_constraint_type type)
+{
+ struct constraint *constraint;
+ int (*add)(struct constraint *constraint, void *data);
+ void (*remove)(struct constraint *constraint);
+
+ switch (type) {
+ default:
+ return ERR_PTR(-EINVAL);
+ }
+
+ constraint = kzalloc(sizeof(*constraint), GFP_KERNEL);
+ if (!constraint)
+ return ERR_PTR(-ENOMEM);
+
+ constraint->cdev = cdev;
+ constraint->type = type;
+ constraint->add = add;
+ constraint->remove = remove;
+ INIT_LIST_HEAD(&constraint->node);
+
+ list_add(&constraint->node, &cdev->constraints);
+
+ return constraint;
+}
+
+static void constraint_free(struct constraint *constraint)
+{
+ list_del(&constraint->node);
+ kfree(constraint);
+}
+
+/**
+ * dev_boot_constraint_add: Adds a boot constraint.
+ *
+ * @dev: Device for which the boot constraint is getting added.
+ * @info: Structure representing the boot constraint.
+ *
+ * This routine adds a single boot constraint for the device. This must be
+ * called before the device is probed by its driver, otherwise the boot
+ * constraint will never get removed and may result in unwanted behavior of the
+ * hardware. The boot constraint is removed by the driver core automatically
+ * after the device is probed (successfully or unsuccessfully).
+ *
+ * Return: 0 on success, and a negative error otherwise.
+ */
+int dev_boot_constraint_add(struct device *dev,
+ struct dev_boot_constraint_info *info)
+{
+ struct constraint_dev *cdev;
+ struct constraint *constraint;
+ int ret;
+
+ mutex_lock(&constraint_devices_mutex);
+
+ /* Find or add the cdev type first */
+ cdev = constraint_device_get(dev);
+ if (IS_ERR(cdev)) {
+ ret = PTR_ERR(cdev);
+ goto unlock;
+ }
+
+ constraint = constraint_allocate(cdev, info->constraint.type);
+ if (IS_ERR(constraint)) {
+ dev_err(dev, "Failed to add constraint type: %d (%ld)\n",
+ info->constraint.type, PTR_ERR(constraint));
+ ret = PTR_ERR(constraint);
+ goto put_cdev;
+ }
+
+ constraint->free_resources = info->free_resources;
+ constraint->free_resources_data = info->free_resources_data;
+
+ /* Set constraint */
+ ret = constraint->add(constraint, info->constraint.data);
+ if (ret)
+ goto free_constraint;
+
+ dev_dbg(dev, "Added boot constraint-type (%d)\n",
+ info->constraint.type);
+
+ mutex_unlock(&constraint_devices_mutex);
+
+ return 0;
+
+free_constraint:
+ constraint_free(constraint);
+put_cdev:
+ constraint_device_put(cdev);
+unlock:
+ mutex_unlock(&constraint_devices_mutex);
+
+ return ret;
+}
+EXPORT_SYMBOL_GPL(dev_boot_constraint_add);
+
+static void constraint_remove(struct constraint *constraint)
+{
+ constraint->remove(constraint);
+
+ if (constraint->free_resources)
+ constraint->free_resources(constraint->free_resources_data);
+
+ constraint_free(constraint);
+}
+
+/**
+ * dev_boot_constraints_remove: Removes all boot constraints of a device.
+ *
+ * @dev: Device for which the boot constraints are getting removed.
+ *
+ * This routine removes all the boot constraints that were previously added for
+ * the device. This is called directly by the driver core and should not be
+ * called by platform specific code.
+ */
+void dev_boot_constraints_remove(struct device *dev)
+{
+ struct constraint_dev *cdev;
+ struct constraint *constraint, *temp;
+
+ mutex_lock(&constraint_devices_mutex);
+
+ cdev = constraint_device_find(dev);
+ if (!cdev)
+ goto unlock;
+
+ for_each_constraint(constraint, temp, cdev)
+ constraint_remove(constraint);
+
+ constraint_device_put(cdev);
+unlock:
+ mutex_unlock(&constraint_devices_mutex);
+}
new file mode 100644
@@ -0,0 +1,30 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (C) 2017 Linaro.
+ * Viresh Kumar <viresh.kumar@linaro.org>
+ */
+#ifndef _CORE_H
+#define _CORE_H
+
+#include <linux/boot_constraint.h>
+#include <linux/device.h>
+#include <linux/list.h>
+
+struct constraint_dev {
+ struct device *dev;
+ struct list_head node;
+ struct list_head constraints;
+};
+
+struct constraint {
+ struct constraint_dev *cdev;
+ struct list_head node;
+ enum dev_boot_constraint_type type;
+ void (*free_resources)(void *data);
+ void *free_resources_data;
+
+ int (*add)(struct constraint *constraint, void *data);
+ void (*remove)(struct constraint *constraint);
+ void *private;
+};
+#endif /* _CORE_H */
new file mode 100644
@@ -0,0 +1,66 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Boot constraints header.
+ *
+ * Copyright (C) 2017 Linaro.
+ * Viresh Kumar <viresh.kumar@linaro.org>
+ */
+#ifndef _LINUX_BOOT_CONSTRAINT_H
+#define _LINUX_BOOT_CONSTRAINT_H
+
+#include <linux/err.h>
+#include <linux/types.h>
+
+struct device;
+
+/**
+ * enum dev_boot_constraint_type - This defines different boot constraint types.
+ *
+ */
+enum dev_boot_constraint_type {
+ DEV_BOOT_CONSTRAINT_NONE,
+};
+
+/**
+ * struct dev_boot_constraint - This represents a single boot constraint.
+ *
+ * @type: This is boot constraint type (like: clk, supply, etc.).
+ * @data: This points to constraint type specific data (like:
+ * dev_boot_constraint_clk_info).
+ */
+struct dev_boot_constraint {
+ enum dev_boot_constraint_type type;
+ void *data;
+};
+
+/**
+ * struct dev_boot_constraint_info - This is used to add a single boot
+ * constraint.
+ *
+ * @constraint: This represents a single boot constraint.
+ * @free_resources: This callback is called by the boot constraint core after
+ * the constraint is removed. This is an optional field.
+ * @free_resources_data: This is data to be passed to free_resources() callback.
+ * This is an optional field.
+ */
+struct dev_boot_constraint_info {
+ struct dev_boot_constraint constraint;
+
+ /* This will be called just before the constraint is removed */
+ void (*free_resources)(void *data);
+ void *free_resources_data;
+};
+
+#ifdef CONFIG_DEV_BOOT_CONSTRAINT
+int dev_boot_constraint_add(struct device *dev,
+ struct dev_boot_constraint_info *info);
+void dev_boot_constraints_remove(struct device *dev);
+#else
+static inline
+int dev_boot_constraint_add(struct device *dev,
+ struct dev_boot_constraint_info *info)
+{ return 0; }
+static inline void dev_boot_constraints_remove(struct device *dev) {}
+#endif /* CONFIG_DEV_BOOT_CONSTRAINT */
+
+#endif /* _LINUX_BOOT_CONSTRAINT_H */