summaryrefslogtreecommitdiffstats
path: root/drivers/amba/bus.c
diff options
context:
space:
mode:
authorDaniel Baumann <daniel.baumann@progress-linux.org>2024-05-06 01:02:30 +0000
committerDaniel Baumann <daniel.baumann@progress-linux.org>2024-05-06 01:02:30 +0000
commit76cb841cb886eef6b3bee341a2266c76578724ad (patch)
treef5892e5ba6cc11949952a6ce4ecbe6d516d6ce58 /drivers/amba/bus.c
parentInitial commit. (diff)
downloadlinux-76cb841cb886eef6b3bee341a2266c76578724ad.tar.xz
linux-76cb841cb886eef6b3bee341a2266c76578724ad.zip
Adding upstream version 4.19.249.upstream/4.19.249
Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>
Diffstat (limited to '')
-rw-r--r--drivers/amba/bus.c774
1 files changed, 774 insertions, 0 deletions
diff --git a/drivers/amba/bus.c b/drivers/amba/bus.c
new file mode 100644
index 000000000..e1992f361
--- /dev/null
+++ b/drivers/amba/bus.c
@@ -0,0 +1,774 @@
+/*
+ * linux/arch/arm/common/amba.c
+ *
+ * Copyright (C) 2003 Deep Blue Solutions Ltd, All Rights Reserved.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ */
+#include <linux/module.h>
+#include <linux/init.h>
+#include <linux/device.h>
+#include <linux/string.h>
+#include <linux/slab.h>
+#include <linux/io.h>
+#include <linux/pm.h>
+#include <linux/pm_runtime.h>
+#include <linux/pm_domain.h>
+#include <linux/amba/bus.h>
+#include <linux/sizes.h>
+#include <linux/limits.h>
+#include <linux/clk/clk-conf.h>
+#include <linux/platform_device.h>
+
+#include <asm/irq.h>
+
+#define to_amba_driver(d) container_of(d, struct amba_driver, drv)
+
+static const struct amba_id *
+amba_lookup(const struct amba_id *table, struct amba_device *dev)
+{
+ int ret = 0;
+
+ while (table->mask) {
+ ret = (dev->periphid & table->mask) == table->id;
+ if (ret)
+ break;
+ table++;
+ }
+
+ return ret ? table : NULL;
+}
+
+static int amba_match(struct device *dev, struct device_driver *drv)
+{
+ struct amba_device *pcdev = to_amba_device(dev);
+ struct amba_driver *pcdrv = to_amba_driver(drv);
+
+ /* When driver_override is set, only bind to the matching driver */
+ if (pcdev->driver_override)
+ return !strcmp(pcdev->driver_override, drv->name);
+
+ return amba_lookup(pcdrv->id_table, pcdev) != NULL;
+}
+
+static int amba_uevent(struct device *dev, struct kobj_uevent_env *env)
+{
+ struct amba_device *pcdev = to_amba_device(dev);
+ int retval = 0;
+
+ retval = add_uevent_var(env, "AMBA_ID=%08x", pcdev->periphid);
+ if (retval)
+ return retval;
+
+ retval = add_uevent_var(env, "MODALIAS=amba:d%08X", pcdev->periphid);
+ return retval;
+}
+
+static ssize_t driver_override_show(struct device *_dev,
+ struct device_attribute *attr, char *buf)
+{
+ struct amba_device *dev = to_amba_device(_dev);
+ ssize_t len;
+
+ device_lock(_dev);
+ len = sprintf(buf, "%s\n", dev->driver_override);
+ device_unlock(_dev);
+ return len;
+}
+
+static ssize_t driver_override_store(struct device *_dev,
+ struct device_attribute *attr,
+ const char *buf, size_t count)
+{
+ struct amba_device *dev = to_amba_device(_dev);
+ char *driver_override, *old, *cp;
+
+ /* We need to keep extra room for a newline */
+ if (count >= (PAGE_SIZE - 1))
+ return -EINVAL;
+
+ driver_override = kstrndup(buf, count, GFP_KERNEL);
+ if (!driver_override)
+ return -ENOMEM;
+
+ cp = strchr(driver_override, '\n');
+ if (cp)
+ *cp = '\0';
+
+ device_lock(_dev);
+ old = dev->driver_override;
+ if (strlen(driver_override)) {
+ dev->driver_override = driver_override;
+ } else {
+ kfree(driver_override);
+ dev->driver_override = NULL;
+ }
+ device_unlock(_dev);
+
+ kfree(old);
+
+ return count;
+}
+static DEVICE_ATTR_RW(driver_override);
+
+#define amba_attr_func(name,fmt,arg...) \
+static ssize_t name##_show(struct device *_dev, \
+ struct device_attribute *attr, char *buf) \
+{ \
+ struct amba_device *dev = to_amba_device(_dev); \
+ return sprintf(buf, fmt, arg); \
+} \
+static DEVICE_ATTR_RO(name)
+
+amba_attr_func(id, "%08x\n", dev->periphid);
+amba_attr_func(irq0, "%u\n", dev->irq[0]);
+amba_attr_func(irq1, "%u\n", dev->irq[1]);
+amba_attr_func(resource, "\t%016llx\t%016llx\t%016lx\n",
+ (unsigned long long)dev->res.start, (unsigned long long)dev->res.end,
+ dev->res.flags);
+
+static struct attribute *amba_dev_attrs[] = {
+ &dev_attr_id.attr,
+ &dev_attr_resource.attr,
+ &dev_attr_driver_override.attr,
+ NULL,
+};
+ATTRIBUTE_GROUPS(amba_dev);
+
+#ifdef CONFIG_PM
+/*
+ * Hooks to provide runtime PM of the pclk (bus clock). It is safe to
+ * enable/disable the bus clock at runtime PM suspend/resume as this
+ * does not result in loss of context.
+ */
+static int amba_pm_runtime_suspend(struct device *dev)
+{
+ struct amba_device *pcdev = to_amba_device(dev);
+ int ret = pm_generic_runtime_suspend(dev);
+
+ if (ret == 0 && dev->driver) {
+ if (pm_runtime_is_irq_safe(dev))
+ clk_disable(pcdev->pclk);
+ else
+ clk_disable_unprepare(pcdev->pclk);
+ }
+
+ return ret;
+}
+
+static int amba_pm_runtime_resume(struct device *dev)
+{
+ struct amba_device *pcdev = to_amba_device(dev);
+ int ret;
+
+ if (dev->driver) {
+ if (pm_runtime_is_irq_safe(dev))
+ ret = clk_enable(pcdev->pclk);
+ else
+ ret = clk_prepare_enable(pcdev->pclk);
+ /* Failure is probably fatal to the system, but... */
+ if (ret)
+ return ret;
+ }
+
+ return pm_generic_runtime_resume(dev);
+}
+#endif /* CONFIG_PM */
+
+static const struct dev_pm_ops amba_pm = {
+ .suspend = pm_generic_suspend,
+ .resume = pm_generic_resume,
+ .freeze = pm_generic_freeze,
+ .thaw = pm_generic_thaw,
+ .poweroff = pm_generic_poweroff,
+ .restore = pm_generic_restore,
+ SET_RUNTIME_PM_OPS(
+ amba_pm_runtime_suspend,
+ amba_pm_runtime_resume,
+ NULL
+ )
+};
+
+/*
+ * Primecells are part of the Advanced Microcontroller Bus Architecture,
+ * so we call the bus "amba".
+ * DMA configuration for platform and AMBA bus is same. So here we reuse
+ * platform's DMA config routine.
+ */
+struct bus_type amba_bustype = {
+ .name = "amba",
+ .dev_groups = amba_dev_groups,
+ .match = amba_match,
+ .uevent = amba_uevent,
+ .dma_configure = platform_dma_configure,
+ .pm = &amba_pm,
+};
+EXPORT_SYMBOL_GPL(amba_bustype);
+
+static int __init amba_init(void)
+{
+ return bus_register(&amba_bustype);
+}
+
+postcore_initcall(amba_init);
+
+static int amba_get_enable_pclk(struct amba_device *pcdev)
+{
+ int ret;
+
+ pcdev->pclk = clk_get(&pcdev->dev, "apb_pclk");
+ if (IS_ERR(pcdev->pclk))
+ return PTR_ERR(pcdev->pclk);
+
+ ret = clk_prepare_enable(pcdev->pclk);
+ if (ret)
+ clk_put(pcdev->pclk);
+
+ return ret;
+}
+
+static void amba_put_disable_pclk(struct amba_device *pcdev)
+{
+ clk_disable_unprepare(pcdev->pclk);
+ clk_put(pcdev->pclk);
+}
+
+/*
+ * These are the device model conversion veneers; they convert the
+ * device model structures to our more specific structures.
+ */
+static int amba_probe(struct device *dev)
+{
+ struct amba_device *pcdev = to_amba_device(dev);
+ struct amba_driver *pcdrv = to_amba_driver(dev->driver);
+ const struct amba_id *id = amba_lookup(pcdrv->id_table, pcdev);
+ int ret;
+
+ do {
+ ret = of_clk_set_defaults(dev->of_node, false);
+ if (ret < 0)
+ break;
+
+ ret = dev_pm_domain_attach(dev, true);
+ if (ret)
+ break;
+
+ ret = amba_get_enable_pclk(pcdev);
+ if (ret) {
+ dev_pm_domain_detach(dev, true);
+ break;
+ }
+
+ pm_runtime_get_noresume(dev);
+ pm_runtime_set_active(dev);
+ pm_runtime_enable(dev);
+
+ ret = pcdrv->probe(pcdev, id);
+ if (ret == 0)
+ break;
+
+ pm_runtime_disable(dev);
+ pm_runtime_set_suspended(dev);
+ pm_runtime_put_noidle(dev);
+
+ amba_put_disable_pclk(pcdev);
+ dev_pm_domain_detach(dev, true);
+ } while (0);
+
+ return ret;
+}
+
+static int amba_remove(struct device *dev)
+{
+ struct amba_device *pcdev = to_amba_device(dev);
+ struct amba_driver *drv = to_amba_driver(dev->driver);
+ int ret = 0;
+
+ pm_runtime_get_sync(dev);
+ if (drv->remove)
+ ret = drv->remove(pcdev);
+ pm_runtime_put_noidle(dev);
+
+ /* Undo the runtime PM settings in amba_probe() */
+ pm_runtime_disable(dev);
+ pm_runtime_set_suspended(dev);
+ pm_runtime_put_noidle(dev);
+
+ amba_put_disable_pclk(pcdev);
+ dev_pm_domain_detach(dev, true);
+
+ return ret;
+}
+
+static void amba_shutdown(struct device *dev)
+{
+ struct amba_driver *drv = to_amba_driver(dev->driver);
+
+ if (drv->shutdown)
+ drv->shutdown(to_amba_device(dev));
+}
+
+/**
+ * amba_driver_register - register an AMBA device driver
+ * @drv: amba device driver structure
+ *
+ * Register an AMBA device driver with the Linux device model
+ * core. If devices pre-exist, the drivers probe function will
+ * be called.
+ */
+int amba_driver_register(struct amba_driver *drv)
+{
+ if (!drv->probe)
+ return -EINVAL;
+
+ drv->drv.bus = &amba_bustype;
+ drv->drv.probe = amba_probe;
+ drv->drv.remove = amba_remove;
+ drv->drv.shutdown = amba_shutdown;
+
+ return driver_register(&drv->drv);
+}
+
+/**
+ * amba_driver_unregister - remove an AMBA device driver
+ * @drv: AMBA device driver structure to remove
+ *
+ * Unregister an AMBA device driver from the Linux device
+ * model. The device model will call the drivers remove function
+ * for each device the device driver is currently handling.
+ */
+void amba_driver_unregister(struct amba_driver *drv)
+{
+ driver_unregister(&drv->drv);
+}
+
+
+static void amba_device_release(struct device *dev)
+{
+ struct amba_device *d = to_amba_device(dev);
+
+ if (d->res.parent)
+ release_resource(&d->res);
+ kfree(d);
+}
+
+static int amba_device_try_add(struct amba_device *dev, struct resource *parent)
+{
+ u32 size;
+ void __iomem *tmp;
+ int i, ret;
+
+ ret = request_resource(parent, &dev->res);
+ if (ret)
+ goto err_out;
+
+ /* Hard-coded primecell ID instead of plug-n-play */
+ if (dev->periphid != 0)
+ goto skip_probe;
+
+ /*
+ * Dynamically calculate the size of the resource
+ * and use this for iomap
+ */
+ size = resource_size(&dev->res);
+ tmp = ioremap(dev->res.start, size);
+ if (!tmp) {
+ ret = -ENOMEM;
+ goto err_release;
+ }
+
+ ret = dev_pm_domain_attach(&dev->dev, true);
+ if (ret) {
+ iounmap(tmp);
+ goto err_release;
+ }
+
+ ret = amba_get_enable_pclk(dev);
+ if (ret == 0) {
+ u32 pid, cid;
+
+ /*
+ * Read pid and cid based on size of resource
+ * they are located at end of region
+ */
+ for (pid = 0, i = 0; i < 4; i++)
+ pid |= (readl(tmp + size - 0x20 + 4 * i) & 255) <<
+ (i * 8);
+ for (cid = 0, i = 0; i < 4; i++)
+ cid |= (readl(tmp + size - 0x10 + 4 * i) & 255) <<
+ (i * 8);
+
+ amba_put_disable_pclk(dev);
+
+ if (cid == AMBA_CID || cid == CORESIGHT_CID)
+ dev->periphid = pid;
+
+ if (!dev->periphid)
+ ret = -ENODEV;
+ }
+
+ iounmap(tmp);
+ dev_pm_domain_detach(&dev->dev, true);
+
+ if (ret)
+ goto err_release;
+
+ skip_probe:
+ ret = device_add(&dev->dev);
+ if (ret)
+ goto err_release;
+
+ if (dev->irq[0])
+ ret = device_create_file(&dev->dev, &dev_attr_irq0);
+ if (ret == 0 && dev->irq[1])
+ ret = device_create_file(&dev->dev, &dev_attr_irq1);
+ if (ret == 0)
+ return ret;
+
+ device_unregister(&dev->dev);
+
+ err_release:
+ release_resource(&dev->res);
+ err_out:
+ return ret;
+}
+
+/*
+ * Registration of AMBA device require reading its pid and cid registers.
+ * To do this, the device must be turned on (if it is a part of power domain)
+ * and have clocks enabled. However in some cases those resources might not be
+ * yet available. Returning EPROBE_DEFER is not a solution in such case,
+ * because callers don't handle this special error code. Instead such devices
+ * are added to the special list and their registration is retried from
+ * periodic worker, until all resources are available and registration succeeds.
+ */
+struct deferred_device {
+ struct amba_device *dev;
+ struct resource *parent;
+ struct list_head node;
+};
+
+static LIST_HEAD(deferred_devices);
+static DEFINE_MUTEX(deferred_devices_lock);
+
+static void amba_deferred_retry_func(struct work_struct *dummy);
+static DECLARE_DELAYED_WORK(deferred_retry_work, amba_deferred_retry_func);
+
+#define DEFERRED_DEVICE_TIMEOUT (msecs_to_jiffies(5 * 1000))
+
+static void amba_deferred_retry_func(struct work_struct *dummy)
+{
+ struct deferred_device *ddev, *tmp;
+
+ mutex_lock(&deferred_devices_lock);
+
+ list_for_each_entry_safe(ddev, tmp, &deferred_devices, node) {
+ int ret = amba_device_try_add(ddev->dev, ddev->parent);
+
+ if (ret == -EPROBE_DEFER)
+ continue;
+
+ list_del_init(&ddev->node);
+ kfree(ddev);
+ }
+
+ if (!list_empty(&deferred_devices))
+ schedule_delayed_work(&deferred_retry_work,
+ DEFERRED_DEVICE_TIMEOUT);
+
+ mutex_unlock(&deferred_devices_lock);
+}
+
+/**
+ * amba_device_add - add a previously allocated AMBA device structure
+ * @dev: AMBA device allocated by amba_device_alloc
+ * @parent: resource parent for this devices resources
+ *
+ * Claim the resource, and read the device cell ID if not already
+ * initialized. Register the AMBA device with the Linux device
+ * manager.
+ */
+int amba_device_add(struct amba_device *dev, struct resource *parent)
+{
+ int ret = amba_device_try_add(dev, parent);
+
+ if (ret == -EPROBE_DEFER) {
+ struct deferred_device *ddev;
+
+ ddev = kmalloc(sizeof(*ddev), GFP_KERNEL);
+ if (!ddev)
+ return -ENOMEM;
+
+ ddev->dev = dev;
+ ddev->parent = parent;
+ ret = 0;
+
+ mutex_lock(&deferred_devices_lock);
+
+ if (list_empty(&deferred_devices))
+ schedule_delayed_work(&deferred_retry_work,
+ DEFERRED_DEVICE_TIMEOUT);
+ list_add_tail(&ddev->node, &deferred_devices);
+
+ mutex_unlock(&deferred_devices_lock);
+ }
+ return ret;
+}
+EXPORT_SYMBOL_GPL(amba_device_add);
+
+static struct amba_device *
+amba_aphb_device_add(struct device *parent, const char *name,
+ resource_size_t base, size_t size, int irq1, int irq2,
+ void *pdata, unsigned int periphid, u64 dma_mask,
+ struct resource *resbase)
+{
+ struct amba_device *dev;
+ int ret;
+
+ dev = amba_device_alloc(name, base, size);
+ if (!dev)
+ return ERR_PTR(-ENOMEM);
+
+ dev->dev.coherent_dma_mask = dma_mask;
+ dev->irq[0] = irq1;
+ dev->irq[1] = irq2;
+ dev->periphid = periphid;
+ dev->dev.platform_data = pdata;
+ dev->dev.parent = parent;
+
+ ret = amba_device_add(dev, resbase);
+ if (ret) {
+ amba_device_put(dev);
+ return ERR_PTR(ret);
+ }
+
+ return dev;
+}
+
+struct amba_device *
+amba_apb_device_add(struct device *parent, const char *name,
+ resource_size_t base, size_t size, int irq1, int irq2,
+ void *pdata, unsigned int periphid)
+{
+ return amba_aphb_device_add(parent, name, base, size, irq1, irq2, pdata,
+ periphid, 0, &iomem_resource);
+}
+EXPORT_SYMBOL_GPL(amba_apb_device_add);
+
+struct amba_device *
+amba_ahb_device_add(struct device *parent, const char *name,
+ resource_size_t base, size_t size, int irq1, int irq2,
+ void *pdata, unsigned int periphid)
+{
+ return amba_aphb_device_add(parent, name, base, size, irq1, irq2, pdata,
+ periphid, ~0ULL, &iomem_resource);
+}
+EXPORT_SYMBOL_GPL(amba_ahb_device_add);
+
+struct amba_device *
+amba_apb_device_add_res(struct device *parent, const char *name,
+ resource_size_t base, size_t size, int irq1,
+ int irq2, void *pdata, unsigned int periphid,
+ struct resource *resbase)
+{
+ return amba_aphb_device_add(parent, name, base, size, irq1, irq2, pdata,
+ periphid, 0, resbase);
+}
+EXPORT_SYMBOL_GPL(amba_apb_device_add_res);
+
+struct amba_device *
+amba_ahb_device_add_res(struct device *parent, const char *name,
+ resource_size_t base, size_t size, int irq1,
+ int irq2, void *pdata, unsigned int periphid,
+ struct resource *resbase)
+{
+ return amba_aphb_device_add(parent, name, base, size, irq1, irq2, pdata,
+ periphid, ~0ULL, resbase);
+}
+EXPORT_SYMBOL_GPL(amba_ahb_device_add_res);
+
+
+static void amba_device_initialize(struct amba_device *dev, const char *name)
+{
+ device_initialize(&dev->dev);
+ if (name)
+ dev_set_name(&dev->dev, "%s", name);
+ dev->dev.release = amba_device_release;
+ dev->dev.bus = &amba_bustype;
+ dev->dev.dma_mask = &dev->dev.coherent_dma_mask;
+ dev->res.name = dev_name(&dev->dev);
+}
+
+/**
+ * amba_device_alloc - allocate an AMBA device
+ * @name: sysfs name of the AMBA device
+ * @base: base of AMBA device
+ * @size: size of AMBA device
+ *
+ * Allocate and initialize an AMBA device structure. Returns %NULL
+ * on failure.
+ */
+struct amba_device *amba_device_alloc(const char *name, resource_size_t base,
+ size_t size)
+{
+ struct amba_device *dev;
+
+ dev = kzalloc(sizeof(*dev), GFP_KERNEL);
+ if (dev) {
+ amba_device_initialize(dev, name);
+ dev->res.start = base;
+ dev->res.end = base + size - 1;
+ dev->res.flags = IORESOURCE_MEM;
+ }
+
+ return dev;
+}
+EXPORT_SYMBOL_GPL(amba_device_alloc);
+
+/**
+ * amba_device_register - register an AMBA device
+ * @dev: AMBA device to register
+ * @parent: parent memory resource
+ *
+ * Setup the AMBA device, reading the cell ID if present.
+ * Claim the resource, and register the AMBA device with
+ * the Linux device manager.
+ */
+int amba_device_register(struct amba_device *dev, struct resource *parent)
+{
+ amba_device_initialize(dev, dev->dev.init_name);
+ dev->dev.init_name = NULL;
+
+ return amba_device_add(dev, parent);
+}
+
+/**
+ * amba_device_put - put an AMBA device
+ * @dev: AMBA device to put
+ */
+void amba_device_put(struct amba_device *dev)
+{
+ put_device(&dev->dev);
+}
+EXPORT_SYMBOL_GPL(amba_device_put);
+
+/**
+ * amba_device_unregister - unregister an AMBA device
+ * @dev: AMBA device to remove
+ *
+ * Remove the specified AMBA device from the Linux device
+ * manager. All files associated with this object will be
+ * destroyed, and device drivers notified that the device has
+ * been removed. The AMBA device's resources including
+ * the amba_device structure will be freed once all
+ * references to it have been dropped.
+ */
+void amba_device_unregister(struct amba_device *dev)
+{
+ device_unregister(&dev->dev);
+}
+
+
+struct find_data {
+ struct amba_device *dev;
+ struct device *parent;
+ const char *busid;
+ unsigned int id;
+ unsigned int mask;
+};
+
+static int amba_find_match(struct device *dev, void *data)
+{
+ struct find_data *d = data;
+ struct amba_device *pcdev = to_amba_device(dev);
+ int r;
+
+ r = (pcdev->periphid & d->mask) == d->id;
+ if (d->parent)
+ r &= d->parent == dev->parent;
+ if (d->busid)
+ r &= strcmp(dev_name(dev), d->busid) == 0;
+
+ if (r) {
+ get_device(dev);
+ d->dev = pcdev;
+ }
+
+ return r;
+}
+
+/**
+ * amba_find_device - locate an AMBA device given a bus id
+ * @busid: bus id for device (or NULL)
+ * @parent: parent device (or NULL)
+ * @id: peripheral ID (or 0)
+ * @mask: peripheral ID mask (or 0)
+ *
+ * Return the AMBA device corresponding to the supplied parameters.
+ * If no device matches, returns NULL.
+ *
+ * NOTE: When a valid device is found, its refcount is
+ * incremented, and must be decremented before the returned
+ * reference.
+ */
+struct amba_device *
+amba_find_device(const char *busid, struct device *parent, unsigned int id,
+ unsigned int mask)
+{
+ struct find_data data;
+
+ data.dev = NULL;
+ data.parent = parent;
+ data.busid = busid;
+ data.id = id;
+ data.mask = mask;
+
+ bus_for_each_dev(&amba_bustype, NULL, &data, amba_find_match);
+
+ return data.dev;
+}
+
+/**
+ * amba_request_regions - request all mem regions associated with device
+ * @dev: amba_device structure for device
+ * @name: name, or NULL to use driver name
+ */
+int amba_request_regions(struct amba_device *dev, const char *name)
+{
+ int ret = 0;
+ u32 size;
+
+ if (!name)
+ name = dev->dev.driver->name;
+
+ size = resource_size(&dev->res);
+
+ if (!request_mem_region(dev->res.start, size, name))
+ ret = -EBUSY;
+
+ return ret;
+}
+
+/**
+ * amba_release_regions - release mem regions associated with device
+ * @dev: amba_device structure for device
+ *
+ * Release regions claimed by a successful call to amba_request_regions.
+ */
+void amba_release_regions(struct amba_device *dev)
+{
+ u32 size;
+
+ size = resource_size(&dev->res);
+ release_mem_region(dev->res.start, size);
+}
+
+EXPORT_SYMBOL(amba_driver_register);
+EXPORT_SYMBOL(amba_driver_unregister);
+EXPORT_SYMBOL(amba_device_register);
+EXPORT_SYMBOL(amba_device_unregister);
+EXPORT_SYMBOL(amba_find_device);
+EXPORT_SYMBOL(amba_request_regions);
+EXPORT_SYMBOL(amba_release_regions);