cxl/pci: Set the device timestamp

CXL r3.0 section 8.2.9.4.2 "Set Timestamp" recommends that the host sets
the timestamp after every Conventional or CXL Reset to ensure accurate
timestamps. This should include on initial boot up. The time base that
is being set is used by a device for the poison list overflow timestamp
and all event timestamps.  Note that the command is optional and if
not supported and the device cannot return accurate timestamps it will
fill the fields in with an appropriate marker (see the specification
description of each timestamp).

Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Link: https://lore.kernel.org/r/20230130151327.32415-1-Jonathan.Cameron@huawei.com
Signed-off-by: Dan Williams <dan.j.williams@intel.com>

1 files changed, 27 insertions, 0 deletions

diff --git a/drivers/cxl/core/mbox.c b/drivers/cxl/core/mbox.c
index 14fa09452f9f..a12255907852 100644
--- a/drivers/cxl/core/mbox.c
+++ b/drivers/cxl/core/mbox.c
@@ -3,6 +3,7 @@
 #include <linux/io-64-nonatomic-lo-hi.h>
 #include <linux/security.h>
 #include <linux/debugfs.h>
+#include <linux/ktime.h>
 #include <linux/mutex.h>
 #include <cxlmem.h>
 #include <cxl.h>
@@ -1055,6 +1056,32 @@ int cxl_mem_create_range_info(struct cxl_dev_state *cxlds)
 }
 EXPORT_SYMBOL_NS_GPL(cxl_mem_create_range_info, CXL);
 
+int cxl_set_timestamp(struct cxl_dev_state *cxlds)
+{
+	struct cxl_mbox_cmd mbox_cmd;
+	struct cxl_mbox_set_timestamp_in pi;
+	int rc;
+
+	pi.timestamp = cpu_to_le64(ktime_get_real_ns());
+	mbox_cmd = (struct cxl_mbox_cmd) {
+		.opcode = CXL_MBOX_OP_SET_TIMESTAMP,
+		.size_in = sizeof(pi),
+		.payload_in = &pi,
+	};
+
+	rc = cxl_internal_send_cmd(cxlds, &mbox_cmd);
+	/*
+	 * Command is optional. Devices may have another way of providing
+	 * a timestamp, or may return all 0s in timestamp fields.
+	 * Don't report an error if this command isn't supported
+	 */
+	if (rc && (mbox_cmd.return_code != CXL_MBOX_CMD_RC_UNSUPPORTED))
+		return rc;
+
+	return 0;
+}
+EXPORT_SYMBOL_NS_GPL(cxl_set_timestamp, CXL);
+
 struct cxl_dev_state *cxl_dev_state_create(struct device *dev)
 {
 	struct cxl_dev_state *cxlds;