| Message ID | 1413298094-9276-4-git-send-email-octavian.purdila@intel.com |
|---|---|
| State | Superseded |
| Headers | show |
On Tue, Oct 14, 2014 at 05:48:14PM +0300, Octavian Purdila wrote: > This patch adds three new sysfs files: bus_frequency, > bus_min_frequency and bus_max_frequency which allows the user to view > or change the bus frequency on a per bus level. > > This is required for the case where multiple busses have the same > adapter driver and where a module parameter does not allow controlling > the bus speed individually (e.g. USB I2C adapters). > > Signed-off-by: Octavian Purdila <octavian.purdila@intel.com> > --- > Documentation/ABI/testing/sysfs-bus-i2c | 30 +++++++++++ > drivers/i2c/i2c-core.c | 94 +++++++++++++++++++++++++++++++++ > include/linux/i2c.h | 16 ++++++ > 3 files changed, 140 insertions(+) > > diff --git a/Documentation/ABI/testing/sysfs-bus-i2c b/Documentation/ABI/testing/sysfs-bus-i2c > index 8075585..4a7f8e7 100644 > --- a/Documentation/ABI/testing/sysfs-bus-i2c > +++ b/Documentation/ABI/testing/sysfs-bus-i2c > @@ -43,3 +43,33 @@ Contact: linux-i2c@vger.kernel.org > Description: > An i2c device attached to bus X that is enumerated via > ACPI. Y is the ACPI device name and its format is "%s". > + > +What: /sys/bus/i2c/devices/i2c-X/bus_frequency > +KernelVersion: 3.19 > +Contact: linux-i2c@vger.kernel.org > +Description: > + The current bus frequency for bus X. Can be updated if > + the bus supports it. The unit is HZ and format is > + "%d\n". > + If the bus does not support changing the frequency > + then this entry will be read-only. > + If the bus does not support showing the frequency than > + this entry will not be visible. > + When updating the bus frequency that value must be in > + the range defined by bus_frequency_min and > + bus_frequency_max otherwise writing to this entry will > + fail with -EINVAL. > + The bus may not support all of the frequencies in the > + min-max range and may round the frequency to the > + closest supported one. The user must read the entry > + after writing it to retrieve the actual set frequency. > + > +What: /sys/bus/i2c/devices/i2c-X/bus_min_frequency > +What: /sys/bus/i2c/devices/i2c-X/bus_max_frequency > +KernelVersion: 3.19 > +Contact: linux-i2c@vger.kernel.org > +Description: > + Minimum and maximum frequencies for bus X. The unit is > + HZ and format is "%d\n". > + If the bus does not support changing the frequency > + these entries will not be visible. > diff --git a/drivers/i2c/i2c-core.c b/drivers/i2c/i2c-core.c > index 632057a..ab77f7f 100644 > --- a/drivers/i2c/i2c-core.c > +++ b/drivers/i2c/i2c-core.c > @@ -940,15 +940,101 @@ static DEVICE_ATTR(new_device, S_IWUSR, NULL, i2c_sysfs_new_device); > static DEVICE_ATTR_IGNORE_LOCKDEP(delete_device, S_IWUSR, NULL, > i2c_sysfs_delete_device); > > +static ssize_t > +i2c_sysfs_freq_show(struct device *dev, struct device_attribute *attr, > + char *buf) > +{ > + struct i2c_adapter *adap = to_i2c_adapter(dev); > + > + return snprintf(buf, PAGE_SIZE, "%d\n", adap->freq); > +} > + > +static ssize_t > +i2c_sysfs_freq_store(struct device *dev, struct device_attribute *attr, > + const char *buf, size_t count) > +{ > + struct i2c_adapter *adap = to_i2c_adapter(dev); > + unsigned int freq; > + int ret; > + > + if (kstrtouint(buf, 0, &freq) || freq < adap->min_freq || > + freq > adap->max_freq) > + return -EINVAL; > + > + i2c_lock_adapter(adap); > + ret = adap->set_freq(adap, &freq); > + i2c_unlock_adapter(adap); > + > + if (ret) > + return ret; > + > + adap->freq = freq; > + > + return count; > +} > + > +static DEVICE_ATTR(bus_frequency, S_IRUGO, i2c_sysfs_freq_show, > + i2c_sysfs_freq_store); Consider using DEVICE_ATTR_RO here. Also, extra empty line. > + > + > +static ssize_t > +i2c_sysfs_min_freq_show(struct device *dev, struct device_attribute *attr, > + char *buf) > +{ > + struct i2c_adapter *adap = to_i2c_adapter(dev); > + > + return snprintf(buf, PAGE_SIZE, "%d\n", adap->min_freq); > +} > + > +static DEVICE_ATTR(bus_min_frequency, S_IRUGO, i2c_sysfs_min_freq_show, NULL); > + Consider using DEVICE_ATTR_RO. > +static ssize_t > +i2c_sysfs_max_freq_show(struct device *dev, struct device_attribute *attr, > + char *buf) > +{ > + struct i2c_adapter *adap = to_i2c_adapter(dev); > + > + return snprintf(buf, PAGE_SIZE, "%d\n", adap->max_freq); > +} > + > +static DEVICE_ATTR(bus_max_frequency, S_IRUGO, i2c_sysfs_max_freq_show, NULL); > + Consider using DEVICE_ATTR_RO. Overall, it seems to me that the bus_ in front of the attrribute names is really not necessary. The attributes are attached to the adapter, so it should be obvious that the attributes describe the adapter (=bus) frequency and not some other frequency. > +umode_t i2c_adapter_visible_attr(struct kobject *kobj, > + struct attribute *attr, int idx) static umode_t > +{ > + struct device *dev = container_of(kobj, struct device, kobj); > + struct i2c_adapter *adap = to_i2c_adapter(dev); > + umode_t mode = attr->mode; > + > + if (attr == &dev_attr_bus_min_frequency.attr) > + return adap->min_freq ? mode : 0; > + > + if (attr == &dev_attr_bus_max_frequency.attr) > + return adap->max_freq ? mode : 0; > + > + if (attr == &dev_attr_bus_frequency.attr) { > + if (adap->set_freq) > + mode |= S_IWUSR; > + return adap->freq ? mode : 0; Personally, I would make all those attributes only visible if the adapter supports setting the frquency, and not bother with other conditions, to keep things simple. Not a strong call, though. > + } > + > + return mode; > +} > + > + extra empty line > static struct attribute *i2c_adapter_attrs[] = { > &dev_attr_name.attr, > &dev_attr_new_device.attr, > &dev_attr_delete_device.attr, > + &dev_attr_bus_frequency.attr, > + &dev_attr_bus_min_frequency.attr, > + &dev_attr_bus_max_frequency.attr, > NULL > }; > > static struct attribute_group i2c_adapter_attr_group = { > .attrs = i2c_adapter_attrs, > + .is_visible = i2c_adapter_visible_attr, > }; > > static const struct attribute_group *i2c_adapter_attr_groups[] = { > @@ -1262,6 +1348,14 @@ int i2c_add_adapter(struct i2c_adapter *adapter) > struct device *dev = &adapter->dev; > int id; > > + if (adapter->set_freq) { > + if (!adapter->freq || !adapter->min_freq || !adapter->max_freq) > + return -EINVAL; > + } else { > + if (adapter->min_freq || adapter->max_freq) > + return -EINVAL; > + } > + > if (dev->of_node) { > id = of_alias_get_id(dev->of_node, "i2c"); > if (id >= 0) { > diff --git a/include/linux/i2c.h b/include/linux/i2c.h > index 36041e2..3482b09 100644 > --- a/include/linux/i2c.h > +++ b/include/linux/i2c.h > @@ -431,6 +431,17 @@ int i2c_generic_scl_recovery(struct i2c_adapter *adap); > * usb->interface->dev, platform_device->dev etc.) > * @name: name of this i2c bus > * @bus_recovery_info: see struct i2c_bus_recovery_info. Optional. > + * @set_freq: set the bus frequency (in HZ) and returns the actual set > + * value. Since not all the freqeuncies in the min - max interval > + * may be valid the driver may round the frequency to the closest > + * supported one. Optional but must be set if min_freq or > + * max_freq is set. > + * @min_freq: minimum bus frequency. Optional but must be set if > + * set_freq is set. > + * @max_freq: maximum bus frequency. Optional but must be set if > + * set_freq is set. > + * @freq: initial bus frequency. Optional but must be set if set_freq > + * is set. > */ > struct i2c_adapter { > struct module *owner; > @@ -438,6 +449,11 @@ struct i2c_adapter { > const struct i2c_algorithm *algo; /* the algorithm to access the bus */ > void *algo_data; > > + unsigned int freq; > + unsigned int min_freq; > + unsigned int max_freq; > + int (*set_freq)(struct i2c_adapter *a, unsigned int *freq); > + > /* data fields that are valid for all devices */ > struct rt_mutex bus_lock; > > -- > 1.9.1 > -- To unsubscribe from this list: send the line "unsubscribe linux-i2c" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
On Tue, Oct 14, 2014 at 6:41 PM, Guenter Roeck <linux@roeck-us.net> wrote: > > On Tue, Oct 14, 2014 at 05:48:14PM +0300, Octavian Purdila wrote: > > This patch adds three new sysfs files: bus_frequency, > > bus_min_frequency and bus_max_frequency which allows the user to view > > or change the bus frequency on a per bus level. > > <snip> > > + > > +static DEVICE_ATTR(bus_frequency, S_IRUGO, i2c_sysfs_freq_show, > > + i2c_sysfs_freq_store); > > Consider using DEVICE_ATTR_RO here. Also, extra empty line. > Unfortunately that won't work because we must transform bus_frequency to a RW entry (via is_visible) if the bus can change the frequency. We can't use DEVIE_ATTR_RW either, because transforming a RW entry to a RO entry with is visible is not possible: fs/sysfs/group.c: static int create_files(struct kernfs_node *parent, struct kobject *kobj, ... if (grp->is_visible) { mode = grp->is_visible(kobj, *attr, i); if (!mode) continue; } error = sysfs_add_file_mode_ns(parent, *attr, false, (*attr)->mode | mode, NULL); Of course if we only allow a RW frequency entry as you suggest below, then we can use DEVICE_ATTR_RW. > > + > > + > > +static ssize_t > > +i2c_sysfs_min_freq_show(struct device *dev, struct device_attribute *attr, > > + char *buf) > > +{ > > + struct i2c_adapter *adap = to_i2c_adapter(dev); > > + > > + return snprintf(buf, PAGE_SIZE, "%d\n", adap->min_freq); > > +} > > + > > +static DEVICE_ATTR(bus_min_frequency, S_IRUGO, i2c_sysfs_min_freq_show, NULL); > > + > > Consider using DEVICE_ATTR_RO. > OK. > > +static ssize_t > > +i2c_sysfs_max_freq_show(struct device *dev, struct device_attribute *attr, > > + char *buf) > > +{ > > + struct i2c_adapter *adap = to_i2c_adapter(dev); > > + > > + return snprintf(buf, PAGE_SIZE, "%d\n", adap->max_freq); > > +} > > + > > +static DEVICE_ATTR(bus_max_frequency, S_IRUGO, i2c_sysfs_max_freq_show, NULL); > > + > Consider using DEVICE_ATTR_RO. > OK. > Overall, it seems to me that the bus_ in front of the attrribute names > is really not necessary. The attributes are attached to the adapter, so it > should be obvious that the attributes describe the adapter (=bus) frequency and > not some other frequency. > > > +umode_t i2c_adapter_visible_attr(struct kobject *kobj, > > + struct attribute *attr, int idx) > > static umode_t > Oops :) > > +{ > > + struct device *dev = container_of(kobj, struct device, kobj); > > + struct i2c_adapter *adap = to_i2c_adapter(dev); > > + umode_t mode = attr->mode; > > + > > + if (attr == &dev_attr_bus_min_frequency.attr) > > + return adap->min_freq ? mode : 0; > > + > > + if (attr == &dev_attr_bus_max_frequency.attr) > > + return adap->max_freq ? mode : 0; > > + > > + if (attr == &dev_attr_bus_frequency.attr) { > > + if (adap->set_freq) > > + mode |= S_IWUSR; > > + return adap->freq ? mode : 0; > > Personally, I would make all those attributes only visible if the adapter > supports setting the frquency, and not bother with other conditions, > to keep things simple. Not a strong call, though. > I don't have a strong opinion either. I think a RO frequency entry would help with debugging, but I am not sure how useful it is in practice. -- To unsubscribe from this list: send the line "unsubscribe linux-i2c" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
On 10/15/2014 04:49 AM, Octavian Purdila wrote: > On Tue, Oct 14, 2014 at 6:41 PM, Guenter Roeck <linux@roeck-us.net> wrote: >> >> On Tue, Oct 14, 2014 at 05:48:14PM +0300, Octavian Purdila wrote: >>> This patch adds three new sysfs files: bus_frequency, >>> bus_min_frequency and bus_max_frequency which allows the user to view >>> or change the bus frequency on a per bus level. >>> > > <snip> > >>> + >>> +static DEVICE_ATTR(bus_frequency, S_IRUGO, i2c_sysfs_freq_show, >>> + i2c_sysfs_freq_store); >> >> Consider using DEVICE_ATTR_RO here. Also, extra empty line. >> > > Unfortunately that won't work because we must transform bus_frequency > to a RW entry (via is_visible) if the bus can change the frequency. We Ah yes, you are right. > can't use DEVIE_ATTR_RW either, because transforming a RW entry to a > RO entry with is visible is not possible: > Why not ? is_visible returns the desired mode. Just like you can return mode | S_IWUSR, you can return mode & ~S_IWUSR. Am I missing something ? Guenter -- To unsubscribe from this list: send the line "unsubscribe linux-i2c" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
On Wed, Oct 15, 2014 at 4:13 PM, Guenter Roeck <linux@roeck-us.net> wrote: > On 10/15/2014 04:49 AM, Octavian Purdila wrote: >> >> On Tue, Oct 14, 2014 at 6:41 PM, Guenter Roeck <linux@roeck-us.net> wrote: >>> >>> >>> On Tue, Oct 14, 2014 at 05:48:14PM +0300, Octavian Purdila wrote: >>>> >>>> This patch adds three new sysfs files: bus_frequency, >>>> bus_min_frequency and bus_max_frequency which allows the user to view >>>> or change the bus frequency on a per bus level. >>>> >> >> <snip> >> >>>> + >>>> +static DEVICE_ATTR(bus_frequency, S_IRUGO, i2c_sysfs_freq_show, >>>> + i2c_sysfs_freq_store); >>> >>> >>> Consider using DEVICE_ATTR_RO here. Also, extra empty line. >>> >> >> Unfortunately that won't work because we must transform bus_frequency >> to a RW entry (via is_visible) if the bus can change the frequency. We > > > Ah yes, you are right. > >> can't use DEVIE_ATTR_RW either, because transforming a RW entry to a >> RO entry with is visible is not possible: >> > > Why not ? > > is_visible returns the desired mode. Just like you can return mode | > S_IWUSR, > you can return mode & ~S_IWUSR. > > Am I missing something ? > Here is how sysfs uses is_visible: static int create_files(struct kernfs_node *parent, struct kobject *kobj, ... if (grp->is_visible) { mode = grp->is_visible(kobj, *attr, i); if (!mode) continue; } error = sysfs_add_file_mode_ns(parent, *attr, false, (*attr)->mode | mode, NULL); so basically is the mode set is the original mode from the attributed "or-ed" with the mode return by is_visible. -- To unsubscribe from this list: send the line "unsubscribe linux-i2c" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
On 10/15/2014 06:32 AM, Octavian Purdila wrote: > On Wed, Oct 15, 2014 at 4:13 PM, Guenter Roeck <linux@roeck-us.net> wrote: >> On 10/15/2014 04:49 AM, Octavian Purdila wrote: >>> >>> On Tue, Oct 14, 2014 at 6:41 PM, Guenter Roeck <linux@roeck-us.net> wrote: >>>> >>>> >>>> On Tue, Oct 14, 2014 at 05:48:14PM +0300, Octavian Purdila wrote: >>>>> >>>>> This patch adds three new sysfs files: bus_frequency, >>>>> bus_min_frequency and bus_max_frequency which allows the user to view >>>>> or change the bus frequency on a per bus level. >>>>> >>> >>> <snip> >>> >>>>> + >>>>> +static DEVICE_ATTR(bus_frequency, S_IRUGO, i2c_sysfs_freq_show, >>>>> + i2c_sysfs_freq_store); >>>> >>>> >>>> Consider using DEVICE_ATTR_RO here. Also, extra empty line. >>>> >>> >>> Unfortunately that won't work because we must transform bus_frequency >>> to a RW entry (via is_visible) if the bus can change the frequency. We >> >> >> Ah yes, you are right. >> >>> can't use DEVIE_ATTR_RW either, because transforming a RW entry to a >>> RO entry with is visible is not possible: >>> >> >> Why not ? >> >> is_visible returns the desired mode. Just like you can return mode | >> S_IWUSR, >> you can return mode & ~S_IWUSR. >> >> Am I missing something ? >> > > Here is how sysfs uses is_visible: > > static int create_files(struct kernfs_node *parent, struct kobject *kobj, > ... > if (grp->is_visible) { > mode = grp->is_visible(kobj, *attr, i); > if (!mode) > continue; > } > error = sysfs_add_file_mode_ns(parent, *attr, false, > (*attr)->mode | mode, > NULL); > > so basically is the mode set is the original mode from the attributed > "or-ed" with the mode return by is_visible. > Ah, you are right. That's a new one for me. Thanks, I didn't notice earlier. Good to know ;-). Guenter -- To unsubscribe from this list: send the line "unsubscribe linux-i2c" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
diff --git a/Documentation/ABI/testing/sysfs-bus-i2c b/Documentation/ABI/testing/sysfs-bus-i2c index 8075585..4a7f8e7 100644 --- a/Documentation/ABI/testing/sysfs-bus-i2c +++ b/Documentation/ABI/testing/sysfs-bus-i2c @@ -43,3 +43,33 @@ Contact: linux-i2c@vger.kernel.org Description: An i2c device attached to bus X that is enumerated via ACPI. Y is the ACPI device name and its format is "%s". + +What: /sys/bus/i2c/devices/i2c-X/bus_frequency +KernelVersion: 3.19 +Contact: linux-i2c@vger.kernel.org +Description: + The current bus frequency for bus X. Can be updated if + the bus supports it. The unit is HZ and format is + "%d\n". + If the bus does not support changing the frequency + then this entry will be read-only. + If the bus does not support showing the frequency than + this entry will not be visible. + When updating the bus frequency that value must be in + the range defined by bus_frequency_min and + bus_frequency_max otherwise writing to this entry will + fail with -EINVAL. + The bus may not support all of the frequencies in the + min-max range and may round the frequency to the + closest supported one. The user must read the entry + after writing it to retrieve the actual set frequency. + +What: /sys/bus/i2c/devices/i2c-X/bus_min_frequency +What: /sys/bus/i2c/devices/i2c-X/bus_max_frequency +KernelVersion: 3.19 +Contact: linux-i2c@vger.kernel.org +Description: + Minimum and maximum frequencies for bus X. The unit is + HZ and format is "%d\n". + If the bus does not support changing the frequency + these entries will not be visible. diff --git a/drivers/i2c/i2c-core.c b/drivers/i2c/i2c-core.c index 632057a..ab77f7f 100644 --- a/drivers/i2c/i2c-core.c +++ b/drivers/i2c/i2c-core.c @@ -940,15 +940,101 @@ static DEVICE_ATTR(new_device, S_IWUSR, NULL, i2c_sysfs_new_device); static DEVICE_ATTR_IGNORE_LOCKDEP(delete_device, S_IWUSR, NULL, i2c_sysfs_delete_device); +static ssize_t +i2c_sysfs_freq_show(struct device *dev, struct device_attribute *attr, + char *buf) +{ + struct i2c_adapter *adap = to_i2c_adapter(dev); + + return snprintf(buf, PAGE_SIZE, "%d\n", adap->freq); +} + +static ssize_t +i2c_sysfs_freq_store(struct device *dev, struct device_attribute *attr, + const char *buf, size_t count) +{ + struct i2c_adapter *adap = to_i2c_adapter(dev); + unsigned int freq; + int ret; + + if (kstrtouint(buf, 0, &freq) || freq < adap->min_freq || + freq > adap->max_freq) + return -EINVAL; + + i2c_lock_adapter(adap); + ret = adap->set_freq(adap, &freq); + i2c_unlock_adapter(adap); + + if (ret) + return ret; + + adap->freq = freq; + + return count; +} + +static DEVICE_ATTR(bus_frequency, S_IRUGO, i2c_sysfs_freq_show, + i2c_sysfs_freq_store); + + +static ssize_t +i2c_sysfs_min_freq_show(struct device *dev, struct device_attribute *attr, + char *buf) +{ + struct i2c_adapter *adap = to_i2c_adapter(dev); + + return snprintf(buf, PAGE_SIZE, "%d\n", adap->min_freq); +} + +static DEVICE_ATTR(bus_min_frequency, S_IRUGO, i2c_sysfs_min_freq_show, NULL); + +static ssize_t +i2c_sysfs_max_freq_show(struct device *dev, struct device_attribute *attr, + char *buf) +{ + struct i2c_adapter *adap = to_i2c_adapter(dev); + + return snprintf(buf, PAGE_SIZE, "%d\n", adap->max_freq); +} + +static DEVICE_ATTR(bus_max_frequency, S_IRUGO, i2c_sysfs_max_freq_show, NULL); + +umode_t i2c_adapter_visible_attr(struct kobject *kobj, + struct attribute *attr, int idx) +{ + struct device *dev = container_of(kobj, struct device, kobj); + struct i2c_adapter *adap = to_i2c_adapter(dev); + umode_t mode = attr->mode; + + if (attr == &dev_attr_bus_min_frequency.attr) + return adap->min_freq ? mode : 0; + + if (attr == &dev_attr_bus_max_frequency.attr) + return adap->max_freq ? mode : 0; + + if (attr == &dev_attr_bus_frequency.attr) { + if (adap->set_freq) + mode |= S_IWUSR; + return adap->freq ? mode : 0; + } + + return mode; +} + + static struct attribute *i2c_adapter_attrs[] = { &dev_attr_name.attr, &dev_attr_new_device.attr, &dev_attr_delete_device.attr, + &dev_attr_bus_frequency.attr, + &dev_attr_bus_min_frequency.attr, + &dev_attr_bus_max_frequency.attr, NULL }; static struct attribute_group i2c_adapter_attr_group = { .attrs = i2c_adapter_attrs, + .is_visible = i2c_adapter_visible_attr, }; static const struct attribute_group *i2c_adapter_attr_groups[] = { @@ -1262,6 +1348,14 @@ int i2c_add_adapter(struct i2c_adapter *adapter) struct device *dev = &adapter->dev; int id; + if (adapter->set_freq) { + if (!adapter->freq || !adapter->min_freq || !adapter->max_freq) + return -EINVAL; + } else { + if (adapter->min_freq || adapter->max_freq) + return -EINVAL; + } + if (dev->of_node) { id = of_alias_get_id(dev->of_node, "i2c"); if (id >= 0) { diff --git a/include/linux/i2c.h b/include/linux/i2c.h index 36041e2..3482b09 100644 --- a/include/linux/i2c.h +++ b/include/linux/i2c.h @@ -431,6 +431,17 @@ int i2c_generic_scl_recovery(struct i2c_adapter *adap); * usb->interface->dev, platform_device->dev etc.) * @name: name of this i2c bus * @bus_recovery_info: see struct i2c_bus_recovery_info. Optional. + * @set_freq: set the bus frequency (in HZ) and returns the actual set + * value. Since not all the freqeuncies in the min - max interval + * may be valid the driver may round the frequency to the closest + * supported one. Optional but must be set if min_freq or + * max_freq is set. + * @min_freq: minimum bus frequency. Optional but must be set if + * set_freq is set. + * @max_freq: maximum bus frequency. Optional but must be set if + * set_freq is set. + * @freq: initial bus frequency. Optional but must be set if set_freq + * is set. */ struct i2c_adapter { struct module *owner; @@ -438,6 +449,11 @@ struct i2c_adapter { const struct i2c_algorithm *algo; /* the algorithm to access the bus */ void *algo_data; + unsigned int freq; + unsigned int min_freq; + unsigned int max_freq; + int (*set_freq)(struct i2c_adapter *a, unsigned int *freq); + /* data fields that are valid for all devices */ struct rt_mutex bus_lock;
This patch adds three new sysfs files: bus_frequency, bus_min_frequency and bus_max_frequency which allows the user to view or change the bus frequency on a per bus level. This is required for the case where multiple busses have the same adapter driver and where a module parameter does not allow controlling the bus speed individually (e.g. USB I2C adapters). Signed-off-by: Octavian Purdila <octavian.purdila@intel.com> --- Documentation/ABI/testing/sysfs-bus-i2c | 30 +++++++++++ drivers/i2c/i2c-core.c | 94 +++++++++++++++++++++++++++++++++ include/linux/i2c.h | 16 ++++++ 3 files changed, 140 insertions(+)