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, 126 insertions, 1 deletions

diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c
index 84c757ba0664..8b44cff2c176 100644
--- a/drivers/pci/pci.c
+++ b/drivers/pci/pci.c
@@ -744,6 +744,104 @@ int pci_enable_device(struct pci_dev *dev)
 	return pci_enable_device_bars(dev, (1 << PCI_NUM_RESOURCES) - 1);
 }
 
+/*
+ * Managed PCI resources.  This manages device on/off, intx/msi/msix
+ * on/off and BAR regions.  pci_dev itself records msi/msix status, so
+ * there's no need to track it separately.  pci_devres is initialized
+ * when a device is enabled using managed PCI device enable interface.
+ */
+struct pci_devres {
+	unsigned int disable:1;
+	unsigned int orig_intx:1;
+	unsigned int restore_intx:1;
+	u32 region_mask;
+};
+
+static void pcim_release(struct device *gendev, void *res)
+{
+	struct pci_dev *dev = container_of(gendev, struct pci_dev, dev);
+	struct pci_devres *this = res;
+	int i;
+
+	if (dev->msi_enabled)
+		pci_disable_msi(dev);
+	if (dev->msix_enabled)
+		pci_disable_msix(dev);
+
+	for (i = 0; i < DEVICE_COUNT_RESOURCE; i++)
+		if (this->region_mask & (1 << i))
+			pci_release_region(dev, i);
+
+	if (this->restore_intx)
+		pci_intx(dev, this->orig_intx);
+
+	if (this->disable)
+		pci_disable_device(dev);
+}
+
+static struct pci_devres * get_pci_dr(struct pci_dev *pdev)
+{
+	struct pci_devres *dr, *new_dr;
+
+	dr = devres_find(&pdev->dev, pcim_release, NULL, NULL);
+	if (dr)
+		return dr;
+
+	new_dr = devres_alloc(pcim_release, sizeof(*new_dr), GFP_KERNEL);
+	if (!new_dr)
+		return NULL;
+	return devres_get(&pdev->dev, new_dr, NULL, NULL);
+}
+
+static struct pci_devres * find_pci_dr(struct pci_dev *pdev)
+{
+	if (pci_is_managed(pdev))
+		return devres_find(&pdev->dev, pcim_release, NULL, NULL);
+	return NULL;
+}
+
+/**
+ * pcim_enable_device - Managed pci_enable_device()
+ * @pdev: PCI device to be initialized
+ *
+ * Managed pci_enable_device().
+ */
+int pcim_enable_device(struct pci_dev *pdev)
+{
+	struct pci_devres *dr;
+	int rc;
+
+	dr = get_pci_dr(pdev);
+	if (unlikely(!dr))
+		return -ENOMEM;
+	WARN_ON(!!dr->disable);
+
+	rc = pci_enable_device(pdev);
+	if (!rc) {
+		pdev->is_managed = 1;
+		dr->disable = 1;
+	}
+	return rc;
+}
+
+/**
+ * pcim_pin_device - Pin managed PCI device
+ * @pdev: PCI device to pin
+ *
+ * Pin managed PCI device @pdev.  Pinned device won't be disabled on
+ * driver detach.  @pdev must have been enabled with
+ * pcim_enable_device().
+ */
+void pcim_pin_device(struct pci_dev *pdev)
+{
+	struct pci_devres *dr;
+
+	dr = find_pci_dr(pdev);
+	WARN_ON(!dr || !dr->disable);
+	if (dr)
+		dr->disable = 0;
+}
+
 /**
  * pcibios_disable_device - disable arch specific PCI resources for device dev
  * @dev: the PCI device to disable
@@ -767,8 +865,13 @@ void __attribute__ ((weak)) pcibios_disable_device (struct pci_dev *dev) {}
 void
 pci_disable_device(struct pci_dev *dev)
 {
+	struct pci_devres *dr;
 	u16 pci_command;
 
+	dr = find_pci_dr(dev);
+	if (dr)
+		dr->disable = 0;
+
 	if (atomic_sub_return(1, &dev->enable_cnt) != 0)
 		return;
 
@@ -867,6 +970,8 @@ pci_get_interrupt_pin(struct pci_dev *dev, struct pci_dev **bridge)
  */
 void pci_release_region(struct pci_dev *pdev, int bar)
 {
+	struct pci_devres *dr;
+
 	if (pci_resource_len(pdev, bar) == 0)
 		return;
 	if (pci_resource_flags(pdev, bar) & IORESOURCE_IO)
@@ -875,6 +980,10 @@ void pci_release_region(struct pci_dev *pdev, int bar)
 	else if (pci_resource_flags(pdev, bar) & IORESOURCE_MEM)
 		release_mem_region(pci_resource_start(pdev, bar),
 				pci_resource_len(pdev, bar));
+
+	dr = find_pci_dr(pdev);
+	if (dr)
+		dr->region_mask &= ~(1 << bar);
 }
 
 /**
@@ -893,6 +1002,8 @@ void pci_release_region(struct pci_dev *pdev, int bar)
  */
 int pci_request_region(struct pci_dev *pdev, int bar, const char *res_name)
 {
+	struct pci_devres *dr;
+
 	if (pci_resource_len(pdev, bar) == 0)
 		return 0;
 		
@@ -906,7 +1017,11 @@ int pci_request_region(struct pci_dev *pdev, int bar, const char *res_name)
 				        pci_resource_len(pdev, bar), res_name))
 			goto err_out;
 	}
-	
+
+	dr = find_pci_dr(pdev);
+	if (dr)
+		dr->region_mask |= 1 << bar;
+
 	return 0;
 
 err_out:
@@ -1144,7 +1259,15 @@ pci_intx(struct pci_dev *pdev, int enable)
 	}
 
 	if (new != pci_command) {
+		struct pci_devres *dr;
+
 		pci_write_config_word(pdev, PCI_COMMAND, new);
+
+		dr = find_pci_dr(pdev);
+		if (dr && !dr->restore_intx) {
+			dr->restore_intx = 1;
+			dr->orig_intx = !enable;
+		}
 	}
 }
 
@@ -1226,6 +1349,8 @@ device_initcall(pci_init);
 EXPORT_SYMBOL_GPL(pci_restore_bars);
 EXPORT_SYMBOL(pci_enable_device_bars);
 EXPORT_SYMBOL(pci_enable_device);
+EXPORT_SYMBOL(pcim_enable_device);
+EXPORT_SYMBOL(pcim_pin_device);
 EXPORT_SYMBOL(pci_disable_device);
 EXPORT_SYMBOL(pci_find_capability);
 EXPORT_SYMBOL(pci_bus_find_capability);