[RFC PATCH 3/4] IPMI: Add the document description of ipmi_get_smi_info

[yakui.zhao@intel.com]

From: Zhao Yakui <yakui.zhao@intel.com>

Add the document description about how to use ipmi_get_smi_info/
ipmi_put_smi_info.

Signed-off-by: Zhao Yakui <yakui.zhao@intel.com>
---
 Documentation/IPMI.txt |   41 +++++++++++++++++++++++++++++++++++++++++
 1 files changed, 41 insertions(+), 0 deletions(-)

diff --git a/Documentation/IPMI.txt b/Documentation/IPMI.txt
index 69dd29e..4683424 100644
--- a/Documentation/IPMI.txt
+++ b/Documentation/IPMI.txt
@@ -533,6 +533,47 @@ completion during sending a panic event.
 Other Pieces
 ------------
 
+Get the detailed info related with the IPMI device
+--------
+The IPMI smi_watcher will be used to catch the IPMI interface as they come or go.
+In order to communicate with the correct IPMI device, it should be confirmed
+ whether it is what we wanted especially on the system with multiple IPMI
+devices. But the new_smi callback function of smi_watcher provides very
+limited info(only the interface number and dev pointer) and there is no
+detailed info about the low level interface. For example: which mechansim
+registers the IPMI interface(ACPI, PCI, DMI and so on).
+    The function of ipmi_get_smi_info/ipmi_put_smi_info is added to get the
+detailed info of IPMI device. The following is the struct definition of
+ipmi_smi_info(Now only ACPI info is defined. If the info is required for
+other IPMI address type, please add it).
+struct ipmi_smi_info{
+	enum ipmi_addr_src addr_src;
+	struct device *dev;
+	/*
+	 * The addr_info can provide more detailed info of one IPMI device.
+	 * Now only SI_ACPI info is provided. And it depends on the SI_ACPI
+	 * address type. If the info is required for other address type, please
+	 * add it.
+	 */
+	union {
+#ifdef CONFIG_ACPI
+		/* the acpi_info element is defined for the SI_ACPI
+		 * address type
+		 */
+		struct {
+			void *acpi_handle;
+		} acpi_info;
+#endif
+		u8 addr_data[8]; /* This is only to reserve 8 bytes space */
+	} addr_info;
+};
+	It is noted that the dev pointer is included in the above structure
+definition. In order to assure that the device is correctly accessed, the
+increment/decrement of the reference count is considered. The reference count
+is increased in the function of ipmi_get_smi_info while it is decreased in
+the function of ipmi_put_smi_info. In such case the ipmi_put_smi_info must be
+called after the ipmi_get_smi_info is called successfully.
+
 Watchdog
 --------
 
-- 
1.5.4.5