cxl: Export AFU error buffer via sysfs

Export the "AFU Error Buffer" via sysfs attribute (afu_err_buf). AFU
error buffer is used by the AFU to report application specific
errors. The contents of this buffer are AFU specific and are intended to
be interpreted by the application interacting with the afu.

Suggested-by: Michael Neuling <mikey@neuling.org>
Signed-off-by: Vaibhav Jain <vaibhav@linux.vnet.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

1 files changed, 33 insertions, 0 deletions

diff --git a/drivers/misc/cxl/sysfs.c b/drivers/misc/cxl/sysfs.c
index d0c38c7bc0c4..4942d55ba77f 100644
--- a/drivers/misc/cxl/sysfs.c
+++ b/drivers/misc/cxl/sysfs.c
@@ -356,6 +356,16 @@ static ssize_t api_version_compatible_show(struct device *device,
 	return scnprintf(buf, PAGE_SIZE, "%i\n", CXL_API_VERSION_COMPATIBLE);
 }
 
+static ssize_t afu_eb_read(struct file *filp, struct kobject *kobj,
+			       struct bin_attribute *bin_attr, char *buf,
+			       loff_t off, size_t count)
+{
+	struct cxl_afu *afu = to_cxl_afu(container_of(kobj,
+						      struct device, kobj));
+
+	return cxl_afu_read_err_buffer(afu, buf, off, count);
+}
+
 static struct device_attribute afu_attrs[] = {
 	__ATTR_RO(mmio_size),
 	__ATTR_RO(irqs_min),
@@ -534,6 +544,10 @@ void cxl_sysfs_afu_remove(struct cxl_afu *afu)
 	struct afu_config_record *cr, *tmp;
 	int i;
 
+	/* remove the err buffer bin attribute */
+	if (afu->eb_len)
+		device_remove_bin_file(&afu->dev, &afu->attr_eb);
+
 	for (i = 0; i < ARRAY_SIZE(afu_attrs); i++)
 		device_remove_file(&afu->dev, &afu_attrs[i]);
 
@@ -555,6 +569,22 @@ int cxl_sysfs_afu_add(struct cxl_afu *afu)
 			goto err;
 	}
 
+	/* conditionally create the add the binary file for error info buffer */
+	if (afu->eb_len) {
+		afu->attr_eb.attr.name = "afu_err_buff";
+		afu->attr_eb.attr.mode = S_IRUGO;
+		afu->attr_eb.size = afu->eb_len;
+		afu->attr_eb.read = afu_eb_read;
+
+		rc = device_create_bin_file(&afu->dev, &afu->attr_eb);
+		if (rc) {
+			dev_err(&afu->dev,
+				"Unable to create eb attr for the afu. Err(%d)\n",
+				rc);
+			goto err;
+		}
+	}
+
 	for (i = 0; i < afu->crs_num; i++) {
 		cr = cxl_sysfs_afu_new_cr(afu, i);
 		if (IS_ERR(cr)) {
@@ -570,6 +600,9 @@ err1:
 	cxl_sysfs_afu_remove(afu);
 	return rc;
 err:
+	/* reset the eb_len as we havent created the bin attr */
+	afu->eb_len = 0;
+
 	for (i--; i >= 0; i--)
 		device_remove_file(&afu->dev, &afu_attrs[i]);
 	return rc;