diff mbox series

[v4] PM / devfreq: Add debugfs support with devfreq_summary file

Message ID 20200116050313.3564-1-cw00.choi@samsung.com (mailing list archive)
State Superseded, archived
Headers show
Series [v4] PM / devfreq: Add debugfs support with devfreq_summary file | expand

Commit Message

Chanwoo Choi Jan. 16, 2020, 5:03 a.m. UTC
Add debugfs interface to provide debugging information of devfreq device.
It contains 'devfreq_summary' entry to show the summary of registered
devfreq devices as following and the additional debugfs file will be added.
- /sys/kernel/debug/devfreq/devfreq_summary

[Detailed description of each field of 'devfreq_summary' debugfs file]
- dev_name	: Device name of h/w.
- dev		: Device name made by devfreq core.
- parent_dev	: If devfreq device uses the passive governor,
		  show parent devfreq device name. Otherwise, show 'null'.
- governor	: Devfreq governor.
- polling_ms	: If devfreq device uses the simple_ondemand governor,
		  polling_ms is necessary for the period. (unit: millisecond)
- cur_freq_Hz	: Current Frequency (unit: Hz)
- old_freq_Hz	: Frequency before changing. (unit: Hz)
- new_freq_Hz	: Frequency after changed. (unit: Hz)

[For example on Exynos5422-based Odroid-XU3 board]
$ cat /sys/kernel/debug/devfreq/devfreq_summary
dev_name                       dev        parent_dev governor        polling_ms  cur_freq_Hz  min_freq_Hz  max_freq_Hz
------------------------------ ---------- ---------- --------------- ---------- ------------ ------------ ------------
10c20000.memory-controller     devfreq0   null       simple_ondemand          0    165000000    165000000    825000000
soc:bus_wcore                  devfreq1   null       simple_ondemand         50    532000000     88700000    532000000
soc:bus_noc                    devfreq2   devfreq1   passive                  0    111000000     66600000    111000000
soc:bus_fsys_apb               devfreq3   devfreq1   passive                  0    222000000    111000000    222000000
soc:bus_fsys                   devfreq4   devfreq1   passive                  0    200000000     75000000    200000000
soc:bus_fsys2                  devfreq5   devfreq1   passive                  0    200000000     75000000    200000000
soc:bus_mfc                    devfreq6   devfreq1   passive                  0    333000000     83250000    333000000
soc:bus_gen                    devfreq7   devfreq1   passive                  0    266000000     88700000    266000000
soc:bus_peri                   devfreq8   devfreq1   passive                  0     66600000     66600000     66600000
soc:bus_g2d                    devfreq9   devfreq1   passive                  0    333000000     83250000    333000000
soc:bus_g2d_acp                devfreq10  devfreq1   passive                  0    266000000     66500000    266000000
soc:bus_jpeg                   devfreq11  devfreq1   passive                  0    300000000     75000000    300000000
soc:bus_jpeg_apb               devfreq12  devfreq1   passive                  0    166500000     83250000    166500000
soc:bus_disp1_fimd             devfreq13  devfreq1   passive                  0    200000000    120000000    200000000
soc:bus_disp1                  devfreq14  devfreq1   passive                  0    300000000    120000000    300000000
soc:bus_gscl_scaler            devfreq15  devfreq1   passive                  0    300000000    150000000    300000000
soc:bus_mscl                   devfreq16  devfreq1   passive                  0    666000000     84000000    666000000

[lkp: Reported the build error]
Reported-by: kbuild test robot <lkp@intel.com>
Signed-off-by: Chanwoo Choi <cw00.choi@samsung.com>
---
Changes from v3:
- Remove the unneeded checking of return value when calling debugfs_create_dir
- Add missing IS_ENABLED(CONFIG_DEVFREQ_GOV_PASSIVE) condition
Changes from v2:
- Show 'null' at 'parent_dev' field when governor of devfreq device
  is not passive
Changes from v1:
- Drop the patch about 'devfreq_transitions' debugfs file
- Modify from 'hz' to 'Hz'
- Edit the indentation of 'devfreq_summary' when show summary
- Exchange sequence between PTR_ERR and IS_ERR when debugfs_create_dir


 drivers/devfreq/devfreq.c | 82 +++++++++++++++++++++++++++++++++++++++
 1 file changed, 82 insertions(+)

Comments

Kamil Konieczny Jan. 16, 2020, 9:53 a.m. UTC | #1
Hi Chanwoo,

On 16.01.2020 06:03, Chanwoo Choi wrote:
> Add debugfs interface to provide debugging information of devfreq device.
> It contains 'devfreq_summary' entry to show the summary of registered
> devfreq devices as following and the additional debugfs file will be added.
> - /sys/kernel/debug/devfreq/devfreq_summary
> 
> [Detailed description of each field of 'devfreq_summary' debugfs file]
> - dev_name	: Device name of h/w.
> - dev		: Device name made by devfreq core.
> - parent_dev	: If devfreq device uses the passive governor,
> 		  show parent devfreq device name. Otherwise, show 'null'.
> - governor	: Devfreq governor.
> - polling_ms	: If devfreq device uses the simple_ondemand governor,
> 		  polling_ms is necessary for the period. (unit: millisecond)
> - cur_freq_Hz	: Current Frequency (unit: Hz)

s/Frequency/frequency/

> - old_freq_Hz	: Frequency before changing. (unit: Hz)

min_freq_Hz : Minimum frequency (unit Hz)

> - new_freq_Hz	: Frequency after changed. (unit: Hz)

max_freq_Hz : Maximum frequency (unit Hz)

> 
> [For example on Exynos5422-based Odroid-XU3 board]
> $ cat /sys/kernel/debug/devfreq/devfreq_summary
> dev_name                       dev        parent_dev governor        polling_ms  cur_freq_Hz  min_freq_Hz  max_freq_Hz
> ------------------------------ ---------- ---------- --------------- ---------- ------------ ------------ ------------
> 10c20000.memory-controller     devfreq0   null       simple_ondemand          0    165000000    165000000    825000000
> soc:bus_wcore                  devfreq1   null       simple_ondemand         50    532000000     88700000    532000000
> soc:bus_noc                    devfreq2   devfreq1   passive                  0    111000000     66600000    111000000
> soc:bus_fsys_apb               devfreq3   devfreq1   passive                  0    222000000    111000000    222000000
> soc:bus_fsys                   devfreq4   devfreq1   passive                  0    200000000     75000000    200000000
> soc:bus_fsys2                  devfreq5   devfreq1   passive                  0    200000000     75000000    200000000
> soc:bus_mfc                    devfreq6   devfreq1   passive                  0    333000000     83250000    333000000
> soc:bus_gen                    devfreq7   devfreq1   passive                  0    266000000     88700000    266000000
> soc:bus_peri                   devfreq8   devfreq1   passive                  0     66600000     66600000     66600000
> soc:bus_g2d                    devfreq9   devfreq1   passive                  0    333000000     83250000    333000000
> soc:bus_g2d_acp                devfreq10  devfreq1   passive                  0    266000000     66500000    266000000
> soc:bus_jpeg                   devfreq11  devfreq1   passive                  0    300000000     75000000    300000000
> soc:bus_jpeg_apb               devfreq12  devfreq1   passive                  0    166500000     83250000    166500000
> soc:bus_disp1_fimd             devfreq13  devfreq1   passive                  0    200000000    120000000    200000000
> soc:bus_disp1                  devfreq14  devfreq1   passive                  0    300000000    120000000    300000000
> soc:bus_gscl_scaler            devfreq15  devfreq1   passive                  0    300000000    150000000    300000000
> soc:bus_mscl                   devfreq16  devfreq1   passive                  0    666000000     84000000    666000000
> 
> [lkp: Reported the build error]
> Reported-by: kbuild test robot <lkp@intel.com>
> Signed-off-by: Chanwoo Choi <cw00.choi@samsung.com>
> ---
> Changes from v3:
> - Remove the unneeded checking of return value when calling debugfs_create_dir
> - Add missing IS_ENABLED(CONFIG_DEVFREQ_GOV_PASSIVE) condition
> Changes from v2:
> - Show 'null' at 'parent_dev' field when governor of devfreq device
>   is not passive
> Changes from v1:
> - Drop the patch about 'devfreq_transitions' debugfs file
> - Modify from 'hz' to 'Hz'
> - Edit the indentation of 'devfreq_summary' when show summary
> - Exchange sequence between PTR_ERR and IS_ERR when debugfs_create_dir
> 
> 
>  drivers/devfreq/devfreq.c | 82 +++++++++++++++++++++++++++++++++++++++
>  1 file changed, 82 insertions(+)
> 
> diff --git a/drivers/devfreq/devfreq.c b/drivers/devfreq/devfreq.c
> index 89260b17598f..cceee8bc3c2f 100644
> --- a/drivers/devfreq/devfreq.c
> +++ b/drivers/devfreq/devfreq.c
> @@ -10,6 +10,7 @@
>  #include <linux/kernel.h>
>  #include <linux/kmod.h>
>  #include <linux/sched.h>
> +#include <linux/debugfs.h>
>  #include <linux/errno.h>
>  #include <linux/err.h>
>  #include <linux/init.h>
> @@ -33,6 +34,7 @@
>  #define HZ_PER_KHZ	1000
>  
>  static struct class *devfreq_class;
> +static struct dentry *devfreq_debugfs;
>  
>  /*
>   * devfreq core provides delayed work based load monitoring helper
> @@ -1643,6 +1645,81 @@ static struct attribute *devfreq_attrs[] = {
>  };
>  ATTRIBUTE_GROUPS(devfreq);
>  
> +/**
> + * devfreq_summary_show() - Show the summary of the devfreq devices
> + * @s:		seq_file instance to show the summary of devfreq devices
> + * @data:	not used
> + *
> + * Show the summary of the devfreq devices via 'devfreq_summary' debugfs file.
> + * It helps that user can know the detailed information of the devfreq devices.
> + *
> + * Return 0 always because it shows the information without any data change.
> + */
> +static int devfreq_summary_show(struct seq_file *s, void *data)
> +{
> +	struct devfreq *devfreq;
> +	struct devfreq *p_devfreq = NULL;
> +	unsigned long cur_freq, min_freq, max_freq;
> +	unsigned int polling_ms;
> +
> +	seq_printf(s, "%-30s %-10s %-10s %-15s %10s %12s %12s %12s\n",
> +			"dev_name",
> +			"dev",
> +			"parent_dev",
> +			"governor",
> +			"polling_ms",
> +			"cur_freq_Hz",
> +			"min_freq_Hz",
> +			"max_freq_Hz");
> +	seq_printf(s, "%30s %10s %10s %15s %10s %12s %12s %12s\n",
> +			"------------------------------",
> +			"----------",
> +			"----------",
> +			"---------------",
> +			"----------",
> +			"------------",
> +			"------------",
> +			"------------");
> +
> +	mutex_lock(&devfreq_list_lock);
> +
> +	list_for_each_entry_reverse(devfreq, &devfreq_list, node) {
> +#if IS_ENABLED(CONFIG_DEVFREQ_GOV_PASSIVE)
> +		if (!strncmp(devfreq->governor_name, DEVFREQ_GOV_PASSIVE,
> +							DEVFREQ_NAME_LEN)) {
> +			struct devfreq_passive_data *data = devfreq->data;
> +
> +			if (data)
> +				p_devfreq = data->parent;
> +		} else {
> +			p_devfreq = NULL;
> +		}
> +#endif
> +
> +		mutex_lock(&devfreq->lock);
> +		cur_freq = devfreq->previous_freq,
> +		get_freq_range(devfreq, &min_freq, &max_freq);
> +		polling_ms = devfreq->profile->polling_ms,
> +		mutex_unlock(&devfreq->lock);
> +
> +		seq_printf(s,
> +			"%-30s %-10s %-10s %-15s %10d %12ld %12ld %12ld\n",
> +			dev_name(devfreq->dev.parent),
> +			dev_name(&devfreq->dev),
> +			p_devfreq ? dev_name(&p_devfreq->dev) : "null",
> +			devfreq->governor_name,
> +			polling_ms,
> +			cur_freq,
> +			min_freq,
> +			max_freq);
> +	}
> +
> +	mutex_unlock(&devfreq_list_lock);
> +
> +	return 0;
> +}
> +DEFINE_SHOW_ATTRIBUTE(devfreq_summary);
> +
>  static int __init devfreq_init(void)
>  {
>  	devfreq_class = class_create(THIS_MODULE, "devfreq");
> @@ -1659,6 +1736,11 @@ static int __init devfreq_init(void)
>  	}
>  	devfreq_class->dev_groups = devfreq_groups;
>  
> +	devfreq_debugfs = debugfs_create_dir("devfreq", NULL);
> +	debugfs_create_file("devfreq_summary", 0444,
> +				devfreq_debugfs, NULL,
> +				&devfreq_summary_fops);
> +
>  	return 0;
>  }
>  subsys_initcall(devfreq_init);
>
Chanwoo Choi Jan. 16, 2020, 10:07 a.m. UTC | #2
On 1/16/20 6:53 PM, Kamil Konieczny wrote:
> Hi Chanwoo,
> 
> On 16.01.2020 06:03, Chanwoo Choi wrote:
>> Add debugfs interface to provide debugging information of devfreq device.
>> It contains 'devfreq_summary' entry to show the summary of registered
>> devfreq devices as following and the additional debugfs file will be added.
>> - /sys/kernel/debug/devfreq/devfreq_summary
>>
>> [Detailed description of each field of 'devfreq_summary' debugfs file]
>> - dev_name	: Device name of h/w.
>> - dev		: Device name made by devfreq core.
>> - parent_dev	: If devfreq device uses the passive governor,
>> 		  show parent devfreq device name. Otherwise, show 'null'.
>> - governor	: Devfreq governor.
>> - polling_ms	: If devfreq device uses the simple_ondemand governor,
>> 		  polling_ms is necessary for the period. (unit: millisecond)
>> - cur_freq_Hz	: Current Frequency (unit: Hz)
> 
> s/Frequency/frequency/
> 
>> - old_freq_Hz	: Frequency before changing. (unit: Hz)
> 
> min_freq_Hz : Minimum frequency (unit Hz)
> 
>> - new_freq_Hz	: Frequency after changed. (unit: Hz)
> 
> max_freq_Hz : Maximum frequency (unit Hz)

Right. Thanks for pointing out.

> 
>>
>> [For example on Exynos5422-based Odroid-XU3 board]
>> $ cat /sys/kernel/debug/devfreq/devfreq_summary
>> dev_name                       dev        parent_dev governor        polling_ms  cur_freq_Hz  min_freq_Hz  max_freq_Hz
>> ------------------------------ ---------- ---------- --------------- ---------- ------------ ------------ ------------
>> 10c20000.memory-controller     devfreq0   null       simple_ondemand          0    165000000    165000000    825000000
>> soc:bus_wcore                  devfreq1   null       simple_ondemand         50    532000000     88700000    532000000
>> soc:bus_noc                    devfreq2   devfreq1   passive                  0    111000000     66600000    111000000
>> soc:bus_fsys_apb               devfreq3   devfreq1   passive                  0    222000000    111000000    222000000
>> soc:bus_fsys                   devfreq4   devfreq1   passive                  0    200000000     75000000    200000000
>> soc:bus_fsys2                  devfreq5   devfreq1   passive                  0    200000000     75000000    200000000
>> soc:bus_mfc                    devfreq6   devfreq1   passive                  0    333000000     83250000    333000000
>> soc:bus_gen                    devfreq7   devfreq1   passive                  0    266000000     88700000    266000000
>> soc:bus_peri                   devfreq8   devfreq1   passive                  0     66600000     66600000     66600000
>> soc:bus_g2d                    devfreq9   devfreq1   passive                  0    333000000     83250000    333000000
>> soc:bus_g2d_acp                devfreq10  devfreq1   passive                  0    266000000     66500000    266000000
>> soc:bus_jpeg                   devfreq11  devfreq1   passive                  0    300000000     75000000    300000000
>> soc:bus_jpeg_apb               devfreq12  devfreq1   passive                  0    166500000     83250000    166500000
>> soc:bus_disp1_fimd             devfreq13  devfreq1   passive                  0    200000000    120000000    200000000
>> soc:bus_disp1                  devfreq14  devfreq1   passive                  0    300000000    120000000    300000000
>> soc:bus_gscl_scaler            devfreq15  devfreq1   passive                  0    300000000    150000000    300000000
>> soc:bus_mscl                   devfreq16  devfreq1   passive                  0    666000000     84000000    666000000
>>
>> [lkp: Reported the build error]
>> Reported-by: kbuild test robot <lkp@intel.com>
>> Signed-off-by: Chanwoo Choi <cw00.choi@samsung.com>
>> ---
>> Changes from v3:
>> - Remove the unneeded checking of return value when calling debugfs_create_dir
>> - Add missing IS_ENABLED(CONFIG_DEVFREQ_GOV_PASSIVE) condition
>> Changes from v2:
>> - Show 'null' at 'parent_dev' field when governor of devfreq device
>>   is not passive
>> Changes from v1:
>> - Drop the patch about 'devfreq_transitions' debugfs file
>> - Modify from 'hz' to 'Hz'
>> - Edit the indentation of 'devfreq_summary' when show summary
>> - Exchange sequence between PTR_ERR and IS_ERR when debugfs_create_dir
>>
>>
>>  drivers/devfreq/devfreq.c | 82 +++++++++++++++++++++++++++++++++++++++
>>  1 file changed, 82 insertions(+)
>>
>> diff --git a/drivers/devfreq/devfreq.c b/drivers/devfreq/devfreq.c
>> index 89260b17598f..cceee8bc3c2f 100644
>> --- a/drivers/devfreq/devfreq.c
>> +++ b/drivers/devfreq/devfreq.c
>> @@ -10,6 +10,7 @@
>>  #include <linux/kernel.h>
>>  #include <linux/kmod.h>
>>  #include <linux/sched.h>
>> +#include <linux/debugfs.h>
>>  #include <linux/errno.h>
>>  #include <linux/err.h>
>>  #include <linux/init.h>
>> @@ -33,6 +34,7 @@
>>  #define HZ_PER_KHZ	1000
>>  
>>  static struct class *devfreq_class;
>> +static struct dentry *devfreq_debugfs;
>>  
>>  /*
>>   * devfreq core provides delayed work based load monitoring helper
>> @@ -1643,6 +1645,81 @@ static struct attribute *devfreq_attrs[] = {
>>  };
>>  ATTRIBUTE_GROUPS(devfreq);
>>  
>> +/**
>> + * devfreq_summary_show() - Show the summary of the devfreq devices
>> + * @s:		seq_file instance to show the summary of devfreq devices
>> + * @data:	not used
>> + *
>> + * Show the summary of the devfreq devices via 'devfreq_summary' debugfs file.
>> + * It helps that user can know the detailed information of the devfreq devices.
>> + *
>> + * Return 0 always because it shows the information without any data change.
>> + */
>> +static int devfreq_summary_show(struct seq_file *s, void *data)
>> +{
>> +	struct devfreq *devfreq;
>> +	struct devfreq *p_devfreq = NULL;
>> +	unsigned long cur_freq, min_freq, max_freq;
>> +	unsigned int polling_ms;
>> +
>> +	seq_printf(s, "%-30s %-10s %-10s %-15s %10s %12s %12s %12s\n",
>> +			"dev_name",
>> +			"dev",
>> +			"parent_dev",
>> +			"governor",
>> +			"polling_ms",
>> +			"cur_freq_Hz",
>> +			"min_freq_Hz",
>> +			"max_freq_Hz");
>> +	seq_printf(s, "%30s %10s %10s %15s %10s %12s %12s %12s\n",
>> +			"------------------------------",
>> +			"----------",
>> +			"----------",
>> +			"---------------",
>> +			"----------",
>> +			"------------",
>> +			"------------",
>> +			"------------");
>> +
>> +	mutex_lock(&devfreq_list_lock);
>> +
>> +	list_for_each_entry_reverse(devfreq, &devfreq_list, node) {
>> +#if IS_ENABLED(CONFIG_DEVFREQ_GOV_PASSIVE)
>> +		if (!strncmp(devfreq->governor_name, DEVFREQ_GOV_PASSIVE,
>> +							DEVFREQ_NAME_LEN)) {
>> +			struct devfreq_passive_data *data = devfreq->data;
>> +
>> +			if (data)
>> +				p_devfreq = data->parent;
>> +		} else {
>> +			p_devfreq = NULL;
>> +		}
>> +#endif
>> +
>> +		mutex_lock(&devfreq->lock);
>> +		cur_freq = devfreq->previous_freq,
>> +		get_freq_range(devfreq, &min_freq, &max_freq);
>> +		polling_ms = devfreq->profile->polling_ms,
>> +		mutex_unlock(&devfreq->lock);
>> +
>> +		seq_printf(s,
>> +			"%-30s %-10s %-10s %-15s %10d %12ld %12ld %12ld\n",
>> +			dev_name(devfreq->dev.parent),
>> +			dev_name(&devfreq->dev),
>> +			p_devfreq ? dev_name(&p_devfreq->dev) : "null",
>> +			devfreq->governor_name,
>> +			polling_ms,
>> +			cur_freq,
>> +			min_freq,
>> +			max_freq);
>> +	}
>> +
>> +	mutex_unlock(&devfreq_list_lock);
>> +
>> +	return 0;
>> +}
>> +DEFINE_SHOW_ATTRIBUTE(devfreq_summary);
>> +
>>  static int __init devfreq_init(void)
>>  {
>>  	devfreq_class = class_create(THIS_MODULE, "devfreq");
>> @@ -1659,6 +1736,11 @@ static int __init devfreq_init(void)
>>  	}
>>  	devfreq_class->dev_groups = devfreq_groups;
>>  
>> +	devfreq_debugfs = debugfs_create_dir("devfreq", NULL);
>> +	debugfs_create_file("devfreq_summary", 0444,
>> +				devfreq_debugfs, NULL,
>> +				&devfreq_summary_fops);
>> +
>>  	return 0;
>>  }
>>  subsys_initcall(devfreq_init);
>>
>
diff mbox series

Patch

diff --git a/drivers/devfreq/devfreq.c b/drivers/devfreq/devfreq.c
index 89260b17598f..cceee8bc3c2f 100644
--- a/drivers/devfreq/devfreq.c
+++ b/drivers/devfreq/devfreq.c
@@ -10,6 +10,7 @@ 
 #include <linux/kernel.h>
 #include <linux/kmod.h>
 #include <linux/sched.h>
+#include <linux/debugfs.h>
 #include <linux/errno.h>
 #include <linux/err.h>
 #include <linux/init.h>
@@ -33,6 +34,7 @@ 
 #define HZ_PER_KHZ	1000
 
 static struct class *devfreq_class;
+static struct dentry *devfreq_debugfs;
 
 /*
  * devfreq core provides delayed work based load monitoring helper
@@ -1643,6 +1645,81 @@  static struct attribute *devfreq_attrs[] = {
 };
 ATTRIBUTE_GROUPS(devfreq);
 
+/**
+ * devfreq_summary_show() - Show the summary of the devfreq devices
+ * @s:		seq_file instance to show the summary of devfreq devices
+ * @data:	not used
+ *
+ * Show the summary of the devfreq devices via 'devfreq_summary' debugfs file.
+ * It helps that user can know the detailed information of the devfreq devices.
+ *
+ * Return 0 always because it shows the information without any data change.
+ */
+static int devfreq_summary_show(struct seq_file *s, void *data)
+{
+	struct devfreq *devfreq;
+	struct devfreq *p_devfreq = NULL;
+	unsigned long cur_freq, min_freq, max_freq;
+	unsigned int polling_ms;
+
+	seq_printf(s, "%-30s %-10s %-10s %-15s %10s %12s %12s %12s\n",
+			"dev_name",
+			"dev",
+			"parent_dev",
+			"governor",
+			"polling_ms",
+			"cur_freq_Hz",
+			"min_freq_Hz",
+			"max_freq_Hz");
+	seq_printf(s, "%30s %10s %10s %15s %10s %12s %12s %12s\n",
+			"------------------------------",
+			"----------",
+			"----------",
+			"---------------",
+			"----------",
+			"------------",
+			"------------",
+			"------------");
+
+	mutex_lock(&devfreq_list_lock);
+
+	list_for_each_entry_reverse(devfreq, &devfreq_list, node) {
+#if IS_ENABLED(CONFIG_DEVFREQ_GOV_PASSIVE)
+		if (!strncmp(devfreq->governor_name, DEVFREQ_GOV_PASSIVE,
+							DEVFREQ_NAME_LEN)) {
+			struct devfreq_passive_data *data = devfreq->data;
+
+			if (data)
+				p_devfreq = data->parent;
+		} else {
+			p_devfreq = NULL;
+		}
+#endif
+
+		mutex_lock(&devfreq->lock);
+		cur_freq = devfreq->previous_freq,
+		get_freq_range(devfreq, &min_freq, &max_freq);
+		polling_ms = devfreq->profile->polling_ms,
+		mutex_unlock(&devfreq->lock);
+
+		seq_printf(s,
+			"%-30s %-10s %-10s %-15s %10d %12ld %12ld %12ld\n",
+			dev_name(devfreq->dev.parent),
+			dev_name(&devfreq->dev),
+			p_devfreq ? dev_name(&p_devfreq->dev) : "null",
+			devfreq->governor_name,
+			polling_ms,
+			cur_freq,
+			min_freq,
+			max_freq);
+	}
+
+	mutex_unlock(&devfreq_list_lock);
+
+	return 0;
+}
+DEFINE_SHOW_ATTRIBUTE(devfreq_summary);
+
 static int __init devfreq_init(void)
 {
 	devfreq_class = class_create(THIS_MODULE, "devfreq");
@@ -1659,6 +1736,11 @@  static int __init devfreq_init(void)
 	}
 	devfreq_class->dev_groups = devfreq_groups;
 
+	devfreq_debugfs = debugfs_create_dir("devfreq", NULL);
+	debugfs_create_file("devfreq_summary", 0444,
+				devfreq_debugfs, NULL,
+				&devfreq_summary_fops);
+
 	return 0;
 }
 subsys_initcall(devfreq_init);