[RFC Patch v4 1/1] i2c debug counters as sysfs attributes
Sui Chen
suichen at google.com
Fri Apr 1 11:22:00 AEDT 2022
This change renames the I2C debug counters as suggested, and moves their
processing into the i2c core:
- bus_errors
- transfers
- nacks
- recovery_successes
- recovery_failures
- timeouts
The function i2c_adapter_create_stats_folder creates a stats directory
in the device's sysfs directory to hold the above debug counters.
Did some brief tests with a few test programs that saves/replays I2C
trace by reading hwmon sensors. The test program and hardware run in
QEMU. The test programs are located at
https://gerrit.openbmc-project.xyz/c/openbmc/openbmc-tools/+/52527
(A normal read)
root at gsj:/tmp# cat /sys/class/i2c-adapter/i2c-1/stats/transfers
264
root at gsj:/tmp# ./i2c_bmk_bmc 0
idx=0
Processing 1 inputs
/sys/class/hwmon/hwmon0/temp1_input
(../../devices/platform/ahb/ahb:apb/f0081000.i2c/i2c-1/1-005c/hwmon/hwmon0):
0
[FindTraceEntries] t0=391.000000 t1=393.000000
Found 4 interesting I2C trace entries:
i2c_write: i2c-1 #0 a=05c f=0000 l=1 [00]
i2c_read: i2c-1 #1 a=05c f=0001 l=2
i2c_reply: i2c-1 #1 a=05c f=0001 l=2 [00-00]
i2c_result: i2c-1 n=2 ret=2
root at gsj:/tmp# cat /sys/class/i2c-adapter/i2c-1/stats/transfers
265
(Read from an inexistent address, NACK)
root at gsj:/tmp# cat /sys/class/i2c-adapter/i2c-1/stats/nacks
6
root at gsj:/tmp# cat /sys/class/i2c-adapter/i2c-1/stats/transfers
265
root at gsj:/tmp# cat i2c_trace.txt
i2c_write: i2c-1 #0 a=0ff f=0000 l=1 [00]
i2c_read: i2c-1 #1 a=0ff f=0001 l=2
root at gsj:/tmp# ./i2c_replay_bmc i2c_trace.txt
(program runs and completes)
root at gsj:/tmp# cat /sys/class/i2c-adapter/i2c-1/stats/nacks
12
root at gsj:/tmp# cat /sys/class/i2c-adapter/i2c-1/stats/transfers
265
The program makes 2 attempts, performing 3 I2C operations at each
attempt, which translates to the 6 nack events.
Signed-off-by: Sui Chen <suichen at google.com>
---
drivers/i2c/i2c-core-base.c | 32 ++++++++++++-
drivers/i2c/i2c-dev.c | 94 +++++++++++++++++++++++++++++++++++++
include/linux/i2c.h | 26 ++++++++++
3 files changed, 151 insertions(+), 1 deletion(-)
diff --git a/drivers/i2c/i2c-core-base.c b/drivers/i2c/i2c-core-base.c
index 84f12bf90644..53688b1d855a 100644
--- a/drivers/i2c/i2c-core-base.c
+++ b/drivers/i2c/i2c-core-base.c
@@ -270,11 +270,22 @@ EXPORT_SYMBOL_GPL(i2c_generic_scl_recovery);
int i2c_recover_bus(struct i2c_adapter *adap)
{
+
+ if (adap->stats == NULL)
+ i2c_adapter_create_stats_directory(adap);
+
if (!adap->bus_recovery_info)
return -EBUSY;
dev_dbg(&adap->dev, "Trying i2c bus recovery\n");
- return adap->bus_recovery_info->recover_bus(adap);
+ int ret = adap->bus_recovery_info->recover_bus(adap);
+
+ if (ret == 0)
+ ++(adap->stats->recovery_successes);
+ else
+ ++(adap->stats->recovery_failures);
+
+ return ret;
}
EXPORT_SYMBOL_GPL(i2c_recover_bus);
@@ -2223,6 +2234,23 @@ int __i2c_transfer(struct i2c_adapter *adap, struct i2c_msg *msgs, int num)
trace_i2c_result(adap, num, ret);
}
+ if (adap->stats == NULL) {
+ i2c_adapter_create_stats_directory(adap);
+ }
+
+ if (ret < 0) {
+ if (ret == -ENXIO)
+ ++(adap->stats->nacks);
+ else if (ret == -ETIMEDOUT)
+ ++(adap->stats->timeouts);
+ else
+ ++(adap->stats->bus_errors);
+ }
+
+ if (ret == num) {
+ ++(adap->stats->transfers);
+ }
+
return ret;
}
EXPORT_SYMBOL(__i2c_transfer);
@@ -2485,6 +2513,7 @@ static int i2c_detect(struct i2c_adapter *adapter, struct i2c_driver *driver)
}
kfree(temp_client);
+ i2c_adapter_create_stats_directory(adapter);
return err;
}
@@ -2617,6 +2646,7 @@ void i2c_put_dma_safe_msg_buf(u8 *buf, struct i2c_msg *msg, bool xferred)
kfree(buf);
}
+
EXPORT_SYMBOL_GPL(i2c_put_dma_safe_msg_buf);
MODULE_AUTHOR("Simon G. Vogl <simon at tk.uni-linz.ac.at>");
diff --git a/drivers/i2c/i2c-dev.c b/drivers/i2c/i2c-dev.c
index 77f576e51652..253622706b63 100644
--- a/drivers/i2c/i2c-dev.c
+++ b/drivers/i2c/i2c-dev.c
@@ -767,6 +767,100 @@ static void __exit i2c_dev_exit(void)
unregister_chrdev_region(MKDEV(I2C_MAJOR, 0), I2C_MINORS);
}
+static struct i2c_adapter *kobj_to_adapter(struct device *pdev)
+{
+ struct kobject *dev_kobj;
+ struct device *dev;
+
+ dev_kobj = ((struct kobject *)pdev)->parent;
+ dev = container_of(dev_kobj, struct device, kobj);
+ return to_i2c_adapter(dev);
+}
+
+ssize_t bus_errors_show(struct device *pdev,
+ struct device_attribute *attr, char *buf)
+{
+ return sysfs_emit(buf, "%llu\n", kobj_to_adapter(pdev)->stats->bus_errors);
+}
+DEVICE_ATTR_RO(bus_errors);
+
+ssize_t transfers_show(struct device *pdev,
+ struct device_attribute *attr, char *buf)
+{
+ return sysfs_emit(buf, "%llu\n", kobj_to_adapter(pdev)->stats->transfers);
+}
+DEVICE_ATTR_RO(transfers);
+
+ssize_t nacks_show(struct device *pdev,
+ struct device_attribute *attr, char *buf)
+{
+ return sysfs_emit(buf, "%llu\n", kobj_to_adapter(pdev)->stats->nacks);
+}
+DEVICE_ATTR_RO(nacks);
+
+ssize_t recovery_successes_show(struct device *pdev,
+ struct device_attribute *attr, char *buf)
+{
+ return sysfs_emit(buf, "%llu\n", kobj_to_adapter(pdev)->stats->recovery_successes);
+}
+DEVICE_ATTR_RO(recovery_successes);
+
+ssize_t recovery_failures_show(struct device *pdev,
+ struct device_attribute *attr, char *buf)
+{
+ return sysfs_emit(buf, "%llu\n", kobj_to_adapter(pdev)->stats->recovery_failures);
+}
+DEVICE_ATTR_RO(recovery_failures);
+
+ssize_t timeouts_show(struct device *pdev,
+ struct device_attribute *attr, char *buf)
+{
+ return sysfs_emit(buf, "%llu\n", kobj_to_adapter(pdev)->stats->timeouts);
+}
+DEVICE_ATTR_RO(timeouts);
+
+/**
+ * i2c_adapter_create_stats_directory - creates folder for I2C statistics.
+ * @adapter: the i2c_adapter to create the stats directory for.
+ *
+ * Return: 0 if successful, 1 if failed.
+ */
+int i2c_adapter_create_stats_directory(struct i2c_adapter *adapter)
+{
+ struct i2c_adapter_stats *stats;
+ int ret = 1;
+
+ stats = kzalloc(sizeof(*stats), GFP_KERNEL);
+ if (!stats) {
+ adapter->stats = NULL;
+ return ret;
+ }
+ adapter->stats = stats;
+ adapter->stats->kobj = kobject_create_and_add("stats", &adapter->dev.kobj);
+
+ ret = sysfs_create_file(adapter->stats->kobj, &dev_attr_transfers.attr);
+ if (ret)
+ dev_warn(&adapter->dev, "Failed to create sysfs file for tx_complete_cnt\n");
+
+ ret = sysfs_create_file(adapter->stats->kobj, &dev_attr_bus_errors.attr);
+ if (ret)
+ dev_warn(&adapter->dev, "Failed to create sysfs file for bus_errors\n");
+
+ ret = sysfs_create_file(adapter->stats->kobj, &dev_attr_nacks.attr);
+ if (ret)
+ dev_warn(&adapter->dev, "Failed to create sysfs file for nacks\n");
+
+ ret = sysfs_create_file(adapter->stats->kobj, &dev_attr_recovery_successes.attr);
+ if (ret)
+ dev_warn(&adapter->dev, "Failed to create sysfs file for recovery_successes\n");
+
+ ret = sysfs_create_file(adapter->stats->kobj, &dev_attr_recovery_failures.attr);
+ if (ret)
+ dev_warn(&adapter->dev, "Failed to create sysfs file for recovery_failures\n");
+
+ return ret;
+}
+
MODULE_AUTHOR("Frodo Looijaard <frodol at dds.nl>");
MODULE_AUTHOR("Simon G. Vogl <simon at tk.uni-linz.ac.at>");
MODULE_DESCRIPTION("I2C /dev entries driver");
diff --git a/include/linux/i2c.h b/include/linux/i2c.h
index 3eb60a2e9e61..c8608378da2a 100644
--- a/include/linux/i2c.h
+++ b/include/linux/i2c.h
@@ -21,6 +21,7 @@
#include <linux/of.h> /* for struct device_node */
#include <linux/swab.h> /* for swab16 */
#include <uapi/linux/i2c.h>
+#include <linux/slab.h> /* for kzalloc */
extern struct bus_type i2c_bus_type;
extern struct device_type i2c_adapter_type;
@@ -684,6 +685,25 @@ struct i2c_adapter_quirks {
u16 max_comb_2nd_msg_len;
};
+/**
+ * I2C statistics
+ * The list of statistics are currently copied from npcm7xx.
+ * Perhaps a more universal set of statistics can be used.
+ *
+ * The stats are currently modeled as pointers to members in the bus drivers.
+ * A null pointer indicates the counter is not supported by the bus driver.
+ */
+struct i2c_adapter_stats {
+ struct kobject *kobj;
+
+ u64 transfers;
+ u64 bus_errors;
+ u64 nacks;
+ u64 recovery_successes;
+ u64 recovery_failures;
+ u64 timeouts;
+};
+
/* enforce max_num_msgs = 2 and use max_comb_*_len for length checks */
#define I2C_AQ_COMB BIT(0)
/* first combined message must be write */
@@ -735,12 +755,18 @@ struct i2c_adapter {
struct i2c_bus_recovery_info *bus_recovery_info;
const struct i2c_adapter_quirks *quirks;
+ struct i2c_adapter_stats *stats;
struct irq_domain *host_notify_domain;
struct regulator *bus_regulator;
};
#define to_i2c_adapter(d) container_of(d, struct i2c_adapter, dev)
+int i2c_adapter_create_stats_directory(struct i2c_adapter *adapter);
+
+void i2c_adapter_stats_register_counter(struct i2c_adapter *adapter,
+ const char *counter_name, void *data_source);
+
static inline void *i2c_get_adapdata(const struct i2c_adapter *adap)
{
return dev_get_drvdata(&adap->dev);
--
2.35.1.1094.g7c7d902a7c-goog
More information about the openbmc
mailing list