[SCSI] mpt2sas: Added sysfs support for trace buffer

Added support so the diag ring buffer can be pulled via sysfs
Added three new shost attributes: host_trace_buffer,
host_trace_buffer_enable, and host_trace_buffer_size.  The
host_trace_buffer_enable attribute is used to either post or release
the trace buffers.   The host_trace_buffer_size attribute contains
the size of the trace buffer. The host_trace_buffer atttribute contains
a maximum 4KB window of the buffer. In order to read the entire host buffer,
you will need to write the offset to  host_trace_buffer prior to reading
it. release the host buffer, then write the entire host buffer contents to
a file.
In addition to this enhancement, we moved the automatic posting of host buffers
at driver load time to be called prior to port_enable, instead of after.
That way discovery is available in the host buffer.

Signed-off-by: Kashyap Desai <kashyap.desai@lsi.com>
Signed-off-by: James Bottomley <James.Bottomley@suse.de>

1 files changed, 2 insertions, 0 deletions

diff --git a/drivers/scsi/mpt2sas/mpt2sas_base.h b/drivers/scsi/mpt2sas/mpt2sas_base.h
index a4a731529226..ffe93984e56a 100644
--- a/drivers/scsi/mpt2sas/mpt2sas_base.h
+++ b/drivers/scsi/mpt2sas/mpt2sas_base.h
@@ -750,6 +750,8 @@ struct MPT2SAS_ADAPTER {
 	Mpi2ManufacturingPage10_t manu_pg10;
 	u32		product_specific[MPI2_DIAG_BUF_TYPE_COUNT][23];
 	u32		diagnostic_flags[MPI2_DIAG_BUF_TYPE_COUNT];
+	u32		ring_buffer_offset;
+	u32		ring_buffer_sz;
 };
 
 typedef u8 (*MPT_CALLBACK)(struct MPT2SAS_ADAPTER *ioc, u16 smid, u8 msix_index,