devres: device resource management

Implement device resource management, in short, devres.  A device
driver can allocate arbirary size of devres data which is associated
with a release function.  On driver detach, release function is
invoked on the devres data, then, devres data is freed.

devreses are typed by associated release functions.  Some devreses are
better represented by single instance of the type while others need
multiple instances sharing the same release function.  Both usages are
supported.

devreses can be grouped using devres group such that a device driver
can easily release acquired resources halfway through initialization
or selectively release resources (e.g. resources for port 1 out of 4
ports).

This patch adds devres core including documentation and the following
managed interfaces.

* alloc/free	: devm_kzalloc(), devm_kzfree()
* IO region	: devm_request_region(), devm_release_region()
* IRQ		: devm_request_irq(), devm_free_irq()
* DMA		: dmam_alloc_coherent(), dmam_free_coherent(),
		  dmam_declare_coherent_memory(), dmam_pool_create(),
		  dmam_pool_destroy()
* PCI		: pcim_enable_device(), pcim_pin_device(), pci_is_managed()
* iomap		: devm_ioport_map(), devm_ioport_unmap(), devm_ioremap(),
		  devm_ioremap_nocache(), devm_iounmap(), pcim_iomap_table(),
		  pcim_iomap(), pcim_iounmap()

Signed-off-by: Tejun Heo <htejun@gmail.com>
Signed-off-by: Jeff Garzik <jeff@garzik.org>

1 files changed, 86 insertions, 0 deletions

diff --git a/kernel/irq/manage.c b/kernel/irq/manage.c
index 8b961adc3bd2..c4b7ed1cebf7 100644
--- a/kernel/irq/manage.c
+++ b/kernel/irq/manage.c
@@ -482,3 +482,89 @@ int request_irq(unsigned int irq, irq_handler_t handler,
         return retval;
 }
 EXPORT_SYMBOL(request_irq);
+
+/*
+ * Device resource management aware IRQ request/free implementation.
+ */
+struct irq_devres {
+        unsigned int irq;
+        void *dev_id;
+};
+
+static void devm_irq_release(struct device *dev, void *res)
+{
+        struct irq_devres *this = res;
+
+        free_irq(this->irq, this->dev_id);
+}
+
+static int devm_irq_match(struct device *dev, void *res, void *data)
+{
+        struct irq_devres *this = res, *match = data;
+
+        return this->irq == match->irq && this->dev_id == match->dev_id;
+}
+
+/**
+ *      devm_request_irq - allocate an interrupt line for a managed device
+ *      @dev: device to request interrupt for
+ *      @irq: Interrupt line to allocate
+ *      @handler: Function to be called when the IRQ occurs
+ *      @irqflags: Interrupt type flags
+ *      @devname: An ascii name for the claiming device
+ *      @dev_id: A cookie passed back to the handler function
+ *
+ *      Except for the extra @dev argument, this function takes the
+ *      same arguments and performs the same function as
+ *      request_irq().  IRQs requested with this function will be
+ *      automatically freed on driver detach.
+ *
+ *      If an IRQ allocated with this function needs to be freed
+ *      separately, dev_free_irq() must be used.
+ */
+int devm_request_irq(struct device *dev, unsigned int irq,
+                     irq_handler_t handler, unsigned long irqflags,
+                     const char *devname, void *dev_id)
+{
+        struct irq_devres *dr;
+        int rc;
+
+        dr = devres_alloc(devm_irq_release, sizeof(struct irq_devres),
+                          GFP_KERNEL);
+        if (!dr)
+                return -ENOMEM;
+
+        rc = request_irq(irq, handler, irqflags, devname, dev_id);
+        if (rc) {
+                kfree(dr);
+                return rc;
+        }
+
+        dr->irq = irq;
+        dr->dev_id = dev_id;
+        devres_add(dev, dr);
+
+        return 0;
+}
+EXPORT_SYMBOL(devm_request_irq);
+
+/**
+ *      devm_free_irq - free an interrupt
+ *      @dev: device to free interrupt for
+ *      @irq: Interrupt line to free
+ *      @dev_id: Device identity to free
+ *
+ *      Except for the extra @dev argument, this function takes the
+ *      same arguments and performs the same function as free_irq().
+ *      This function instead of free_irq() should be used to manually
+ *      free IRQs allocated with dev_request_irq().
+ */
+void devm_free_irq(struct device *dev, unsigned int irq, void *dev_id)
+{
+        struct irq_devres match_data = { irq, dev_id };
+
+        free_irq(irq, dev_id);
+        WARN_ON(devres_destroy(dev, devm_irq_release, devm_irq_match,
+                               &match_data));
+}
+EXPORT_SYMBOL(devm_free_irq);