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

The read error log command extracts information from the controller's
internal error log.

This patch exposes this information in 2 ways:
- During probe, if an error occurs & a log is available, print it to the
  console
- After probe, make the error log available to userspace via an IOCTL.
  Userspace is notified of pending error logs in a later patch
  ("nvdimm/ocxl: Forward events to userspace")

Signed-off-by: Alastair D'Silva <alast...@d-silva.org>
---
 drivers/nvdimm/ocxl/scm.c          | 270 +++++++++++++++++++++++++++++
 drivers/nvdimm/ocxl/scm_internal.h |   1 +
 include/uapi/nvdimm/ocxl-scm.h     |  46 +++++
 3 files changed, 317 insertions(+)
 create mode 100644 include/uapi/nvdimm/ocxl-scm.h

diff --git a/drivers/nvdimm/ocxl/scm.c b/drivers/nvdimm/ocxl/scm.c
index c313a473a28e..0bbe1a14291e 100644
--- a/drivers/nvdimm/ocxl/scm.c
+++ b/drivers/nvdimm/ocxl/scm.c
@@ -495,10 +495,220 @@ static int scm_file_release(struct inode *inode, struct 
file *file)
        return 0;
 }
 
+/**
+ * scm_error_log_header_parse() - Parse the first 64 bits of the error log 
command response
+ * @scm_data: the SCM metadata
+ * @length: out, returns the number of bytes in the response (excluding the 64 
bit header)
+ */
+static int scm_error_log_header_parse(struct scm_data *scm_data, u16 *length)
+{
+       int rc;
+       u64 val;
+
+       u16 data_identifier;
+       u32 data_length;
+
+       rc = ocxl_global_mmio_read64(scm_data->ocxl_afu,
+                                    scm_data->admin_command.data_offset,
+                                    OCXL_LITTLE_ENDIAN, &val);
+       if (rc)
+               return rc;
+
+       data_identifier = val >> 48;
+       data_length = val & 0xFFFF;
+
+       if (data_identifier != 0x454C) {
+               dev_err(&scm_data->dev,
+                       "Bad data identifier for error log data, expected 'EL', 
got '%2s' (%#x), data_length=%u\n",
+                       (char *)&data_identifier,
+                       (unsigned int)data_identifier, data_length);
+               return -EINVAL;
+       }
+
+       *length = data_length;
+       return 0;
+}
+
+static int scm_error_log_offset_0x08(struct scm_data *scm_data,
+                                    u32 *log_identifier, u32 *program_ref_code)
+{
+       int rc;
+       u64 val;
+
+       rc = ocxl_global_mmio_read64(scm_data->ocxl_afu,
+                                    scm_data->admin_command.data_offset + 0x08,
+                                    OCXL_LITTLE_ENDIAN, &val);
+       if (rc)
+               return rc;
+
+       *log_identifier = val >> 32;
+       *program_ref_code = val & 0xFFFFFFFF;
+
+       return 0;
+}
+
+static int scm_read_error_log(struct scm_data *scm_data,
+                             struct scm_ioctl_error_log *log, bool buf_is_user)
+{
+       u64 val;
+       u16 user_buf_length;
+       u16 buf_length;
+       u16 i;
+       int rc;
+
+       if (log->buf_size % 8)
+               return -EINVAL;
+
+       rc = scm_chi(scm_data, &val);
+       if (rc)
+               goto out;
+
+       if (!(val & GLOBAL_MMIO_CHI_ELA))
+               return -EAGAIN;
+
+       user_buf_length = log->buf_size;
+
+       mutex_lock(&scm_data->admin_command.lock);
+
+       rc = scm_admin_command_request(scm_data, ADMIN_COMMAND_ERRLOG);
+       if (rc)
+               goto out;
+
+       rc = scm_admin_command_execute(scm_data);
+       if (rc)
+               goto out;
+
+       rc = scm_admin_command_complete_timeout(scm_data, ADMIN_COMMAND_ERRLOG);
+       if (rc < 0) {
+               dev_warn(&scm_data->dev, "Read error log timed out\n");
+               goto out;
+       }
+
+       rc = scm_admin_response(scm_data);
+       if (rc < 0)
+               goto out;
+       if (rc != STATUS_SUCCESS) {
+               scm_warn_status(scm_data, "Unexpected status from retrieve 
error log", rc);
+               goto out;
+       }
+
+
+       rc = scm_error_log_header_parse(scm_data, &log->buf_size);
+       if (rc)
+               goto out;
+       // log->buf_size now contains the scm buffer size, not the user size
+
+       rc = scm_error_log_offset_0x08(scm_data, &log->log_identifier,
+                                      &log->program_reference_code);
+       if (rc)
+               goto out;
+
+       rc = ocxl_global_mmio_read64(scm_data->ocxl_afu,
+                                    scm_data->admin_command.data_offset + 0x10,
+                                    OCXL_LITTLE_ENDIAN, &val);
+       if (rc)
+               goto out;
+
+       log->error_log_type = val >> 56;
+       log->action_flags = (log->error_log_type == SCM_ERROR_LOG_TYPE_GENERAL) 
?
+                           (val >> 32) & 0xFFFFFF : 0;
+       log->power_on_seconds = val & 0xFFFFFFFF;
+
+       rc = ocxl_global_mmio_read64(scm_data->ocxl_afu,
+                                    scm_data->admin_command.data_offset + 0x18,
+                                    OCXL_LITTLE_ENDIAN, &log->timestamp);
+       if (rc)
+               goto out;
+
+       rc = ocxl_global_mmio_read64(scm_data->ocxl_afu,
+                                    scm_data->admin_command.data_offset + 0x20,
+                                    OCXL_HOST_ENDIAN, &log->wwid[0]);
+       if (rc)
+               goto out;
+
+       rc = ocxl_global_mmio_read64(scm_data->ocxl_afu,
+                                    scm_data->admin_command.data_offset + 0x28,
+                                    OCXL_HOST_ENDIAN, &log->wwid[1]);
+       if (rc)
+               goto out;
+
+       rc = ocxl_global_mmio_read64(scm_data->ocxl_afu,
+                                    scm_data->admin_command.data_offset + 0x30,
+                                    OCXL_HOST_ENDIAN, (u64 *)log->fw_revision);
+       if (rc)
+               goto out;
+       log->fw_revision[8] = '\0';
+
+       buf_length = (user_buf_length < log->buf_size) ?
+                    user_buf_length : log->buf_size;
+       for (i = 0; i < buf_length + 0x48; i += 8) {
+               u64 val;
+
+               rc = ocxl_global_mmio_read64(scm_data->ocxl_afu,
+                                            
scm_data->admin_command.data_offset + i,
+                                            OCXL_HOST_ENDIAN, &val);
+               if (rc)
+                       goto out;
+
+               if (buf_is_user) {
+                       if (copy_to_user(&log->buf[i], &val, sizeof(u64))) {
+                               rc = -EFAULT;
+                               goto out;
+                       }
+               } else
+                       log->buf[i] = val;
+       }
+
+       rc = scm_admin_response_handled(scm_data);
+       if (rc)
+               goto out;
+
+out:
+       mutex_unlock(&scm_data->admin_command.lock);
+       return rc;
+
+}
+
+static int scm_ioctl_error_log(struct scm_data *scm_data,
+                              struct scm_ioctl_error_log __user *uarg)
+{
+       struct scm_ioctl_error_log args;
+       int rc;
+
+       if (copy_from_user(&args, uarg, sizeof(args)))
+               return -EFAULT;
+
+       rc = scm_read_error_log(scm_data, &args, true);
+       if (rc)
+               return rc;
+
+       if (copy_to_user(uarg, &args, sizeof(args)))
+               return -EFAULT;
+
+       return 0;
+}
+
+static long scm_file_ioctl(struct file *file, unsigned int cmd,
+                          unsigned long args)
+{
+       struct scm_data *scm_data = file->private_data;
+       int rc = -EINVAL;
+
+       switch (cmd) {
+       case SCM_IOCTL_ERROR_LOG:
+               rc = scm_ioctl_error_log(scm_data,
+                                        (struct scm_ioctl_error_log __user 
*)args);
+               break;
+       }
+       return rc;
+}
+
 static const struct file_operations scm_fops = {
        .owner          = THIS_MODULE,
        .open           = scm_file_open,
        .release        = scm_file_release,
+       .unlocked_ioctl = scm_file_ioctl,
+       .compat_ioctl   = scm_file_ioctl,
 };
 
 /**
@@ -575,6 +785,60 @@ static int read_device_metadata(struct scm_data *scm_data)
        return 0;
 }
 
+static const char *scm_decode_error_log_type(u8 error_log_type)
+{
+       switch (error_log_type) {
+       case 0x00:
+               return "general";
+       case 0x01:
+               return "predictive failure";
+       case 0x02:
+               return "thermal warning";
+       case 0x03:
+               return "data loss";
+       case 0x04:
+               return "health & performance";
+       default:
+               return "unknown";
+       }
+}
+
+static void scm_dump_error_log(struct scm_data *scm_data)
+{
+       struct scm_ioctl_error_log log;
+       u32 buf_size;
+       u8 *buf;
+       int rc;
+
+       if (scm_data->admin_command.data_size == 0)
+               return;
+
+       buf_size = scm_data->admin_command.data_size - 0x48;
+       buf = kzalloc(buf_size, GFP_KERNEL);
+       if (!buf)
+               return;
+
+       log.buf = buf;
+       log.buf_size = buf_size;
+
+       rc = scm_read_error_log(scm_data, &log, false);
+       if (rc < 0)
+               goto out;
+
+       dev_warn(&scm_data->dev,
+                "SCM Error log: WWID=0x%016llx%016llx LID=0x%x PRC=%x 
type=0x%x %s, Uptime=%u seconds timestamp=0x%llx\n",
+                log.wwid[0], log.wwid[1],
+                log.log_identifier, log.program_reference_code,
+                log.error_log_type,
+                scm_decode_error_log_type(log.error_log_type),
+                log.power_on_seconds, log.timestamp);
+       print_hex_dump(KERN_WARNING, "buf", DUMP_PREFIX_OFFSET, 16, 1, buf,
+                      log.buf_size, false);
+
+out:
+       kfree(buf);
+}
+
 /**
  * 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,
@@ -617,6 +881,7 @@ static int scm_probe(struct pci_dev *pdev, const struct 
pci_device_id *ent)
        struct scm_data *scm_data = NULL;
        int elapsed;
        u16 timeout;
+       u64 chi;
 
        if (PCI_FUNC(pdev->devfn) == 0)
                return scm_probe_function_0(pdev);
@@ -707,6 +972,11 @@ static int scm_probe(struct pci_dev *pdev, const struct 
pci_device_id *ent)
        return 0;
 
 err:
+       if (scm_data &&
+                   (scm_chi(scm_data, &chi) == 0) &&
+                   (chi & GLOBAL_MMIO_CHI_ELA))
+               scm_dump_error_log(scm_data);
+
        /*
         * Further cleanup is done in the release handler via free_scm()
         * This allows us to keep the character device live to handle IOCTLs to
diff --git a/drivers/nvdimm/ocxl/scm_internal.h 
b/drivers/nvdimm/ocxl/scm_internal.h
index 57491dbee1a4..9bf8fcf30ea6 100644
--- a/drivers/nvdimm/ocxl/scm_internal.h
+++ b/drivers/nvdimm/ocxl/scm_internal.h
@@ -5,6 +5,7 @@
 #include <linux/cdev.h>
 #include <misc/ocxl.h>
 #include <linux/libnvdimm.h>
+#include <uapi/linux/ocxl-scm.h>
 #include <linux/mm.h>
 
 #define SCM_DEFAULT_TIMEOUT 100
diff --git a/include/uapi/nvdimm/ocxl-scm.h b/include/uapi/nvdimm/ocxl-scm.h
new file mode 100644
index 000000000000..b34dd1ba06ff
--- /dev/null
+++ b/include/uapi/nvdimm/ocxl-scm.h
@@ -0,0 +1,46 @@
+/* SPDX-License-Identifier: GPL-2.0+ WITH Linux-syscall-note */
+/* Copyright 2017 IBM Corp. */
+#ifndef _UAPI_OCXL_SCM_H
+#define _UAPI_OCXL_SCM_H
+
+#include <linux/types.h>
+#include <linux/ioctl.h>
+
+#define SCM_ERROR_LOG_ACTION_RESET     (1 << (32-32))
+#define SCM_ERROR_LOG_ACTION_CHKFW     (1 << (53-32))
+#define SCM_ERROR_LOG_ACTION_REPLACE   (1 << (54-32))
+#define SCM_ERROR_LOG_ACTION_DUMP      (1 << (55-32))
+
+#define SCM_ERROR_LOG_TYPE_GENERAL             (0x00)
+#define SCM_ERROR_LOG_TYPE_PREDICTIVE_FAILURE  (0x01)
+#define SCM_ERROR_LOG_TYPE_THERMAL_WARNING     (0x02)
+#define SCM_ERROR_LOG_TYPE_DATA_LOSS           (0x03)
+#define SCM_ERROR_LOG_TYPE_HEALTH_PERFORMANCE  (0x04)
+
+struct scm_ioctl_error_log {
+       __u32 log_identifier; // out
+       __u32 program_reference_code; // out
+       __u32 action_flags; //out, recommended course of action
+       __u32 power_on_seconds; // out, Number of seconds the controller has 
been on when the error occurred
+       __u64 timestamp; // out, relative time since the current IPL
+       __u64 wwid[2]; // out, the NAA formatted WWID associated with the 
controller
+       char  fw_revision[8+1]; // out, firmware revision as null terminated 
text
+       __u16 buf_size; /* in/out, buffer size provided/required.
+                        * If required is greater than provided, the buffer
+                        * will be truncated to the amount provided. If its
+                        * less, then only the required bytes will be populated.
+                        * If it is 0, then there are no more error log entries.
+                        */
+       __u8  error_log_type;
+       __u8  reserved1;
+       __u32 reserved2;
+       __u64 reserved3[2];
+       __u8 *buf; // pointer to output buffer
+};
+
+/* ioctl numbers */
+#define SCM_MAGIC 0x5C
+/* SCM devices */
+#define SCM_IOCTL_ERROR_LOG    _IOWR(SCM_MAGIC, 0x01, struct 
scm_ioctl_error_log)
+
+#endif /* _UAPI_OCXL_SCM_H */
-- 
2.23.0

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