[RFC Patch v4 1/1] i2c debug counters as sysfs attributes
Avi Fishman
avifishman70 at gmail.com
Sun Apr 3 22:12:04 AEST 2022
Hi Sui,
Do you intend later to push it also to kernel.org?
Avi
On Fri, Apr 1, 2022 at 3:28 AM Sui Chen <suichen at google.com> wrote:
>
> 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
>
--
Regards,
Avi
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