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Subject[PATCH v3 11/12] hwmon (occ): Add error handling
Date
From: "Edward A. James" <eajames@us.ibm.com>

Add logic to detect a number of error scenarios on the OCC. Export any
errors through an additional non-hwmon device attribute. The error
counting and state verification are required by the OCC hardware
specification.

Signed-off-by: Edward A. James <eajames@us.ibm.com>
---
drivers/hwmon/occ/common.c | 55 +++++++++++++++++++++++++++++++++++++++++++++-
drivers/hwmon/occ/common.h | 4 ++++
2 files changed, 58 insertions(+), 1 deletion(-)

diff --git a/drivers/hwmon/occ/common.c b/drivers/hwmon/occ/common.c
index 53e3592..7a0606d 100644
--- a/drivers/hwmon/occ/common.c
+++ b/drivers/hwmon/occ/common.c
@@ -18,6 +18,11 @@

#include "common.h"

+#define OCC_ERROR_COUNT_THRESHOLD 2 /* OCC HW defined */
+
+#define OCC_STATE_SAFE 4
+#define OCC_SAFE_TIMEOUT msecs_to_jiffies(60000) /* 1 min */
+
#define OCC_UPDATE_FREQUENCY msecs_to_jiffies(1000)

#define OCC_TEMP_SENSOR_FAULT 0xFF
@@ -131,10 +136,22 @@ struct extended_sensor {
u8 data[6];
} __packed;

+static ssize_t occ_show_error(struct device *dev,
+ struct device_attribute *attr, char *buf)
+{
+ struct occ *occ = dev_get_drvdata(dev);
+
+ return snprintf(buf, PAGE_SIZE - 1, "%d\n", occ->error);
+}
+
+static DEVICE_ATTR(occ_error, 0444, occ_show_error, NULL);
+
static int occ_poll(struct occ *occ)
{
+ struct occ_poll_response_header *header;
u16 checksum = occ->poll_cmd_data + 1;
u8 cmd[8];
+ int rc;

/* big endian */
cmd[0] = 0; /* sequence number */
@@ -147,7 +164,33 @@ static int occ_poll(struct occ *occ)
cmd[7] = 0;

/* mutex should already be locked if necessary */
- return occ->send_cmd(occ, cmd);
+ rc = occ->send_cmd(occ, cmd);
+ if (rc) {
+ if (occ->error_count++ > OCC_ERROR_COUNT_THRESHOLD)
+ occ->error = rc;
+
+ return rc;
+ }
+
+ /* clear error since communication was successful */
+ occ->error_count = 0;
+ occ->error = 0;
+
+ /* check for safe state */
+ header = (struct occ_poll_response_header *)occ->resp.data;
+ if (header->occ_state == OCC_STATE_SAFE) {
+ if (occ->last_safe) {
+ if (time_after(jiffies,
+ occ->last_safe + OCC_SAFE_TIMEOUT))
+ occ->error = -EHOSTDOWN;
+ } else {
+ occ->last_safe = jiffies;
+ }
+ } else {
+ occ->last_safe = 0;
+ }
+
+ return 0;
}

static int occ_set_user_power_cap(struct occ *occ, u16 user_power_cap)
@@ -176,6 +219,15 @@ static int occ_set_user_power_cap(struct occ *occ, u16 user_power_cap)

mutex_unlock(&occ->lock);

+ if (rc) {
+ if (occ->error_count++ > OCC_ERROR_COUNT_THRESHOLD)
+ occ->error = rc;
+ } else {
+ /* successful communication so clear the error */
+ occ->error_count = 0;
+ occ->error = 0;
+ }
+
return rc;
}

@@ -1184,6 +1236,7 @@ static ssize_t occ_show_status(struct device *dev,
&sensor_dev_attr_occ_quick_drop.dev_attr.attr,
&sensor_dev_attr_occ_status.dev_attr.attr,
&sensor_dev_attr_occs_present.dev_attr.attr,
+ &dev_attr_occ_error.attr,
NULL
};

diff --git a/drivers/hwmon/occ/common.h b/drivers/hwmon/occ/common.h
index dc9e06d..cef2174 100644
--- a/drivers/hwmon/occ/common.h
+++ b/drivers/hwmon/occ/common.h
@@ -107,6 +107,10 @@ struct occ {
struct occ_attribute *attrs;
struct attribute_group group;
const struct attribute_group *groups[2];
+
+ int error;
+ unsigned int error_count; /* number of errors observed */
+ unsigned long last_safe; /* time OCC entered safe state */
};

int occ_setup(struct occ *occ, const char *name);
--
1.8.3.1
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