[RFC Patch v4 1/1] i2c debug counters as sysfs attributes
Avi Fishman
avifishman70 at gmail.com
Wed Apr 13 01:38:46 AEST 2022
Hi Sui
I am not sure that there is a standard that returning -ENXIO means
always NACK, and I am not sure that there are no other cases where we
return -ENXIO which is not NACK, unless you are asking for local
modification that will not be upstreamed.
Also you can know the per-address counters via the 'adap' stract you
use for transfer.
Thanks,
Avi
On Tue, Apr 12, 2022 at 9:57 AM Sui Chen <suichen at google.com> wrote:
>
> Hello Avi,
>
> I recently installed a patched kernel on a real machine and am trying
> to validate the counters a bit; I would like to find out how the
> counters in the i2c core relate to the counters in the npcm7xx driver,
> and also explore the possibility of per-address counters, then update
> to this list and the linux-kernel list when the results are clear.
>
> And also I need to find a better place to create the sysfs folders
> than from within i2c_transfer and i2c_recover_bus.
>
> Thanks,
> Sui
>
>
> On Sun, Apr 3, 2022 at 5:12 AM Avi Fishman <avifishman70 at gmail.com> wrote:
> >
> > 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
--
Regards,
Avi
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