PNP: add interface to retrieve ACPI device from a PNPACPI device

Add pnp_acpi_device(pnp_dev), which takes a PNP device and returns the
associated ACPI device (or NULL, if the device is not a PNPACPI device).

This allows us to write a PNP driver that can manage both traditional
PNPBIOS and ACPI devices, treating ACPI-only functionality as an optional
extension.

Signed-off-by: Bjorn Helgaas <bjorn.helgaas@hp.com>
Signed-off-by: Len Brown <len.brown@intel.com>

2 files changed, 15 insertions, 1 deletions

diff --git a/drivers/pnp/pnpacpi/core.c b/drivers/pnp/pnpacpi/core.c
index b2348fc2378e..5314bf630bc4 100644
--- a/drivers/pnp/pnpacpi/core.c
+++ b/drivers/pnp/pnpacpi/core.c
@@ -144,7 +144,7 @@ static int pnpacpi_resume(struct pnp_dev *dev)
 }
 #endif
 
-static struct pnp_protocol pnpacpi_protocol = {
+struct pnp_protocol pnpacpi_protocol = {
         .name    = "Plug and Play ACPI",
         .get     = pnpacpi_get_resources,
         .set     = pnpacpi_set_resources,
@@ -154,6 +154,7 @@ static struct pnp_protocol pnpacpi_protocol = {
         .resume = pnpacpi_resume,
 #endif
 };
+EXPORT_SYMBOL(pnpacpi_protocol);
 
 static int __init pnpacpi_add_device(struct acpi_device *device)
 {
diff --git a/include/linux/pnp.h b/include/linux/pnp.h
index fddfafaed024..7c4193eb0072 100644
--- a/include/linux/pnp.h
+++ b/include/linux/pnp.h
@@ -334,6 +334,19 @@ extern struct pnp_protocol pnpbios_protocol;
 #define pnp_device_is_pnpbios(dev) 0
 #endif
 
+#ifdef CONFIG_PNPACPI
+extern struct pnp_protocol pnpacpi_protocol;
+
+static inline struct acpi_device *pnp_acpi_device(struct pnp_dev *dev)
+{
+        if (dev->protocol == &pnpacpi_protocol)
+                return dev->data;
+        return NULL;
+}
+#else
+#define pnp_acpi_device(dev) 0
+#endif
+
 /* status */
 #define PNP_READY               0x0000
 #define PNP_ATTACHED            0x0001