[PATCH] cxl/pci: Set the device timestamp

[Jonathan Cameron <Jonathan.Cameron@huawei.com>]

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>

---

Open question: Should we only do this if Linux has control of the
error handling?  In theory it should be safe anyway given the
specification is clear that the timestamp base should always be the
same - so subject to small errors we shouldn't cause any firmware first
handling to get confused.

 drivers/cxl/core/mbox.c      | 25 +++++++++++++++++++++++++
 drivers/cxl/cxlmem.h         |  7 +++++++
 drivers/cxl/pci.c            |  5 +++++
 include/uapi/linux/cxl_mem.h |  1 +
 4 files changed, 38 insertions(+)

diff --git a/drivers/cxl/core/mbox.c b/drivers/cxl/core/mbox.c
index b03fba212799..a7317bb142ed 100644
--- a/drivers/cxl/core/mbox.c
+++ b/drivers/cxl/core/mbox.c
@@ -65,6 +65,7 @@ static struct cxl_mem_command cxl_mem_commands[CXL_MEM_COMMAND_ID_MAX] = {
 	CXL_CMD(GET_SCAN_MEDIA_CAPS, 0x10, 0x4, 0),
 	CXL_CMD(SCAN_MEDIA, 0x11, 0, 0),
 	CXL_CMD(GET_SCAN_MEDIA, 0, CXL_VARIABLE_PAYLOAD, 0),
+	CXL_CMD(SET_TIMESTAMP, 8, 0, 0),
 };
 
 /*
@@ -93,6 +94,7 @@ static u16 cxl_disabled_raw_commands[] = {
 	CXL_MBOX_OP_SET_SHUTDOWN_STATE,
 	CXL_MBOX_OP_SCAN_MEDIA,
 	CXL_MBOX_OP_GET_SCAN_MEDIA,
+	CXL_MBOX_OP_SET_TIMESTAMP,
 };
 
 /*
@@ -857,6 +859,29 @@ 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, u64 ts)
+{
+	struct cxl_mbox_cmd mbox_cmd;
+	struct cxl_mbox_set_timestamp_in pi;
+
+	/*
+	 * Command is optional and functionality should not be affected if
+	 * the command is not available.
+	 */
+	if (!test_bit(CXL_MEM_COMMAND_ID_SET_TIMESTAMP, cxlds->enabled_cmds))
+		return 0;
+
+	pi.timestamp = ts;
+	mbox_cmd = (struct cxl_mbox_cmd) {
+		.opcode = CXL_MBOX_OP_SET_TIMESTAMP,
+		.size_in = sizeof(pi),
+		.payload_in = &pi,
+	};
+
+	return cxl_internal_send_cmd(cxlds, &mbox_cmd);
+}
+EXPORT_SYMBOL_NS_GPL(cxl_set_timestamp, CXL);
+
 struct cxl_dev_state *cxl_dev_state_create(struct device *dev)
 {
 	struct cxl_dev_state *cxlds;
diff --git a/drivers/cxl/cxlmem.h b/drivers/cxl/cxlmem.h
index ab138004f644..0ca7a35de893 100644
--- a/drivers/cxl/cxlmem.h
+++ b/drivers/cxl/cxlmem.h
@@ -274,6 +274,7 @@ enum cxl_opcode {
 	CXL_MBOX_OP_RAW			= CXL_MBOX_OP_INVALID,
 	CXL_MBOX_OP_GET_FW_INFO		= 0x0200,
 	CXL_MBOX_OP_ACTIVATE_FW		= 0x0202,
+	CXL_MBOX_OP_SET_TIMESTAMP	= 0x0301,
 	CXL_MBOX_OP_GET_SUPPORTED_LOGS	= 0x0400,
 	CXL_MBOX_OP_GET_LOG		= 0x0401,
 	CXL_MBOX_OP_IDENTIFY		= 0x4000,
@@ -372,6 +373,11 @@ struct cxl_mbox_set_partition_info {
 
 #define  CXL_SET_PARTITION_IMMEDIATE_FLAG	BIT(0)
 
+/* Set Timestamp CXL 3.0 Spec 8.2.9.4.2 */
+struct cxl_mbox_set_timestamp_in {
+	__le64 timestamp;
+} __packed;
+
 /**
  * struct cxl_mem_command - Driver representation of a memory device command
  * @info: Command information as it exists for the UAPI
@@ -441,6 +447,7 @@ int cxl_mem_create_range_info(struct cxl_dev_state *cxlds);
 struct cxl_dev_state *cxl_dev_state_create(struct device *dev);
 void set_exclusive_cxl_commands(struct cxl_dev_state *cxlds, unsigned long *cmds);
 void clear_exclusive_cxl_commands(struct cxl_dev_state *cxlds, unsigned long *cmds);
+int cxl_set_timestamp(struct cxl_dev_state *cxlds, u64 ts);
 #ifdef CONFIG_CXL_SUSPEND
 void cxl_mem_active_inc(void);
 void cxl_mem_active_dec(void);
diff --git a/drivers/cxl/pci.c b/drivers/cxl/pci.c
index 2bbebbc7e032..30a2b231d970 100644
--- a/drivers/cxl/pci.c
+++ b/drivers/cxl/pci.c
@@ -2,6 +2,7 @@
 /* Copyright(c) 2020 Intel Corporation. All rights reserved. */
 #include <linux/io-64-nonatomic-lo-hi.h>
 #include <linux/moduleparam.h>
+#include <linux/timekeeping.h>
 #include <linux/module.h>
 #include <linux/delay.h>
 #include <linux/sizes.h>
@@ -482,6 +483,10 @@ static int cxl_pci_probe(struct pci_dev *pdev, const struct pci_device_id *id)
 	if (rc)
 		return rc;
 
+	rc = cxl_set_timestamp(cxlds, ktime_get_real_ns());
+	if (rc)
+		return rc;
+
 	rc = cxl_dev_state_identify(cxlds);
 	if (rc)
 		return rc;
diff --git a/include/uapi/linux/cxl_mem.h b/include/uapi/linux/cxl_mem.h
index c71021a2a9ed..333301037b74 100644
--- a/include/uapi/linux/cxl_mem.h
+++ b/include/uapi/linux/cxl_mem.h
@@ -41,6 +41,7 @@
 	___C(GET_SCAN_MEDIA_CAPS, "Get Scan Media Capabilities"),         \
 	___C(SCAN_MEDIA, "Scan Media"),                                   \
 	___C(GET_SCAN_MEDIA, "Get Scan Media Results"),                   \
+	___C(SET_TIMESTAMP, "Set Device Timestamp"),                      \
 	___C(MAX, "invalid / last command")
 
 #define ___C(a, b) CXL_MEM_COMMAND_ID_##a

base-commit: 172738bbccdb4ef76bdd72fc72a315c741c39161
-- 
2.37.2