[PATCH v2 12/27] nvdimm/ocxl: Read the capability registers & wait for device ready

["Alastair D'Silva" <alastair@au1.ibm.com>]

From: Alastair D'Silva <alastair@d-silva.org>

This patch reads timeouts & firmware version from the controller, and
uses those timeouts to wait for the controller to report that it is ready
before handing the memory over to libnvdimm.

Signed-off-by: Alastair D'Silva <alastair@d-silva.org>
---
 drivers/nvdimm/ocxl/Makefile       |  2 +-
 drivers/nvdimm/ocxl/scm.c          | 84 ++++++++++++++++++++++++++++++
 drivers/nvdimm/ocxl/scm_internal.c | 19 +++++++
 drivers/nvdimm/ocxl/scm_internal.h | 24 +++++++++
 4 files changed, 128 insertions(+), 1 deletion(-)
 create mode 100644 drivers/nvdimm/ocxl/scm_internal.c

diff --git a/drivers/nvdimm/ocxl/Makefile b/drivers/nvdimm/ocxl/Makefile
index 74a1bd98848e..9b6e31f0eb3e 100644
--- a/drivers/nvdimm/ocxl/Makefile
+++ b/drivers/nvdimm/ocxl/Makefile
@@ -4,4 +4,4 @@ ccflags-$(CONFIG_PPC_WERROR)	+= -Werror
 
 obj-$(CONFIG_OCXL_SCM) += ocxlscm.o
 
-ocxlscm-y := scm.o
+ocxlscm-y := scm.o scm_internal.o
diff --git a/drivers/nvdimm/ocxl/scm.c b/drivers/nvdimm/ocxl/scm.c
index 571058a9e7b8..8088f65c289e 100644
--- a/drivers/nvdimm/ocxl/scm.c
+++ b/drivers/nvdimm/ocxl/scm.c
@@ -7,6 +7,7 @@
 
 #include <linux/module.h>
 #include <misc/ocxl.h>
+#include <linux/delay.h>
 #include <linux/ndctl.h>
 #include <linux/mm_types.h>
 #include <linux/memory_hotplug.h>
@@ -266,6 +267,30 @@ static int scm_register_lpc_mem(struct scm_data *scm_data)
 	return 0;
 }
 
+/**
+ * scm_is_usable() - Is a controller usable?
+ * @scm_data: a pointer to the SCM device data
+ * Return: true if the controller is usable
+ */
+static bool scm_is_usable(const struct scm_data *scm_data)
+{
+	u64 chi = 0;
+	int rc = scm_chi(scm_data, &chi);
+
+	if (!(chi & GLOBAL_MMIO_CHI_CRDY)) {
+		dev_err(&scm_data->dev, "SCM controller is not ready.\n");
+		return false;
+	}
+
+	if (!(chi & GLOBAL_MMIO_CHI_MA)) {
+		dev_err(&scm_data->dev,
+			"SCM controller does not have memory available.\n");
+		return false;
+	}
+
+	return true;
+}
+
 /**
  * allocate_scm_minor() - Allocate a minor number to use for an SCM device
  * @scm_data: The SCM device to associate the minor with
@@ -380,6 +405,48 @@ static void scm_remove(struct pci_dev *pdev)
 	}
 }
 
+/**
+ * read_device_metadata() - Retrieve config information from the AFU and save it for future use
+ * @scm_data: the SCM metadata
+ * Return: 0 on success, negative on failure
+ */
+static int read_device_metadata(struct scm_data *scm_data)
+{
+	u64 val;
+	int rc;
+
+	rc = ocxl_global_mmio_read64(scm_data->ocxl_afu, GLOBAL_MMIO_CCAP0,
+				     OCXL_LITTLE_ENDIAN, &val);
+	if (rc)
+		return rc;
+
+	scm_data->scm_revision = val & 0xFFFF;
+	scm_data->read_latency = (val >> 32) & 0xFF;
+	scm_data->readiness_timeout = (val >> 48) & 0xff;
+	scm_data->memory_available_timeout = val >> 52;
+
+	rc = ocxl_global_mmio_read64(scm_data->ocxl_afu, GLOBAL_MMIO_CCAP1,
+				     OCXL_LITTLE_ENDIAN, &val);
+	if (rc)
+		return rc;
+
+	scm_data->max_controller_dump_size = val & 0xFFFFFFFF;
+
+	// Extract firmware version text
+	rc = ocxl_global_mmio_read64(scm_data->ocxl_afu, GLOBAL_MMIO_FWVER,
+				     OCXL_HOST_ENDIAN, (u64 *)scm_data->fw_version);
+	if (rc)
+		return rc;
+
+	scm_data->fw_version[8] = '\0';
+
+	dev_info(&scm_data->dev,
+		 "Firmware version '%s' SCM revision %d:%d\n", scm_data->fw_version,
+		 scm_data->scm_revision >> 4, scm_data->scm_revision & 0x0F);
+
+	return 0;
+}
+
 /**
  * scm_probe_function_0 - Set up function 0 for an OpenCAPI Storage Class Memory device
  * This is important as it enables templates higher than 0 across all other functions,
@@ -420,6 +487,8 @@ static int scm_probe_function_0(struct pci_dev *pdev)
 static int scm_probe(struct pci_dev *pdev, const struct pci_device_id *ent)
 {
 	struct scm_data *scm_data = NULL;
+	int elapsed;
+	u16 timeout;
 
 	if (PCI_FUNC(pdev->devfn) == 0)
 		return scm_probe_function_0(pdev);
@@ -469,6 +538,21 @@ static int scm_probe(struct pci_dev *pdev, const struct pci_device_id *ent)
 		goto err;
 	}
 
+	if (read_device_metadata(scm_data)) {
+		dev_err(&pdev->dev, "Could not read SCM device metadata\n");
+		goto err;
+	}
+
+	elapsed = 0;
+	timeout = scm_data->readiness_timeout + scm_data->memory_available_timeout;
+	while (!scm_is_usable(scm_data)) {
+		if (elapsed++ > timeout) {
+			dev_warn(&scm_data->dev, "SCM ready timeout.\n");
+			goto err;
+		}
+
+		msleep(1000);
+	}
 	if (scm_register_lpc_mem(scm_data)) {
 		dev_err(&pdev->dev, "Could not register OCXL SCM memory with libnvdimm\n");
 		goto err;
diff --git a/drivers/nvdimm/ocxl/scm_internal.c b/drivers/nvdimm/ocxl/scm_internal.c
new file mode 100644
index 000000000000..72d3c0e7d846
--- /dev/null
+++ b/drivers/nvdimm/ocxl/scm_internal.c
@@ -0,0 +1,19 @@
+// SPDX-License-Identifier: GPL-2.0+
+// Copyright 2019 IBM Corp.
+
+#include <misc/ocxl.h>
+#include <linux/delay.h>
+#include "scm_internal.h"
+
+int scm_chi(const struct scm_data *scm_data, u64 *chi)
+{
+	u64 val;
+	int rc = ocxl_global_mmio_read64(scm_data->ocxl_afu, GLOBAL_MMIO_CHI,
+					 OCXL_LITTLE_ENDIAN, &val);
+	if (rc)
+		return rc;
+
+	*chi = val;
+
+	return 0;
+}
diff --git a/drivers/nvdimm/ocxl/scm_internal.h b/drivers/nvdimm/ocxl/scm_internal.h
index d6ab361f5de9..584450f55e30 100644
--- a/drivers/nvdimm/ocxl/scm_internal.h
+++ b/drivers/nvdimm/ocxl/scm_internal.h
@@ -97,4 +97,28 @@ struct scm_data {
 	void *metadata_addr;
 	struct resource scm_res;
 	struct nd_region *nd_region;
+	char fw_version[8+1];
+
+	u32 max_controller_dump_size;
+	u16 scm_revision; // major/minor
+	u8 readiness_timeout;  /* The worst case time (in seconds) that the host shall
+				* wait for the controller to become operational following a reset (CHI.CRDY).
+				*/
+	u8 memory_available_timeout;   /* The worst case time (in seconds) that the host shall
+					* wait for memory to become available following a reset (CHI.MA).
+					*/
+
+	u16 read_latency; /* The nominal measure of latency (in nanoseconds)
+			   * associated with an unassisted read of a memory block.
+			   * This represents the capability of the raw media technology without assistance
+			   */
 };
+
+/**
+ * scm_chi() - Get the value of the CHI register
+ * @scm_data: The SCM metadata
+ * @chi: returns the CHI value
+ *
+ * Returns 0 on success, negative on error
+ */
+int scm_chi(const struct scm_data *scm_data, u64 *chi);
-- 
2.23.0
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