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Date: Thu, 10 Aug 2017 15:23:11 -0500
From: Eddie James <eajames@...ux.vnet.ibm.com>
To: Guenter Roeck <linux@...ck-us.net>
Cc: jdelvare@...e.com, linux-hwmon@...r.kernel.org,
linux-kernel@...r.kernel.org, joel@....id.au, jk@...abs.org,
andrew@...id.au, cbostic@...ux.vnet.ibm.com,
"Edward A. James" <eajames@...ibm.com>
Subject: Re: [PATCH 4/4] drivers/hwmon/pmbus: Add debugfs for status registers
On 08/10/2017 03:15 PM, Eddie James wrote:
>
>
> On 08/09/2017 08:15 PM, Guenter Roeck wrote:
>> On Wed, Aug 09, 2017 at 05:19:17PM -0500, Eddie James wrote:
>>> From: "Edward A. James" <eajames@...ibm.com>
>>>
>>> Export all the available status registers through debugfs, if the
>>> client
>>> driver wants them.
>>>
>>> Signed-off-by: Edward A. James <eajames@...ibm.com>
>>> ---
>>> drivers/hwmon/pmbus/pmbus.c | 24 +++++-
>>> drivers/hwmon/pmbus/pmbus.h | 11 +++
>>> drivers/hwmon/pmbus/pmbus_core.c | 175
>>> +++++++++++++++++++++++++++++++++++++++
>>> 3 files changed, 209 insertions(+), 1 deletion(-)
>>>
>>> diff --git a/drivers/hwmon/pmbus/pmbus.c b/drivers/hwmon/pmbus/pmbus.c
>>> index 7718e58..fc27417 100644
>>> --- a/drivers/hwmon/pmbus/pmbus.c
>>> +++ b/drivers/hwmon/pmbus/pmbus.c
>> That won't work: SENSORS_PMBUS is independent of PMBUS and does not have
>> to be enabled even if PMBUS is enabled. This will have to be in
>> pmbus_core.c.
>>
>> I would suggest to do the same as done with other drivers. Move
>> pmbus_debugfs_dir into pmbus_core.c and create the directory on probe
>> if it has not already been created.
>
> Hmm, I'm having trouble with this. Don't I have to call
> debugfs_recursive_remove() on the pmbus_debugfs_dir when the pmbus
> driver is unloaded? That can't be done from pmbus_core.c, as that is
> just device probe/remove. I agree it makes sense to only create it if
> a device is going to be using it (and is enabled in the kernel) but I
> think I need to declare it here so I can remove it on unload.
Sorry was a bit confused about which file was compiled with what CONFIG.
I should create pmbus_debugfs_dir in pmbus_core.c, agreed. But I should
still do the remove in pmbus.c I think.
>
>>
>>> @@ -18,6 +18,7 @@
>>> * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
>>> */
>>> +#include <linux/debugfs.h>
>>> #include <linux/kernel.h>
>>> #include <linux/module.h>
>>> #include <linux/init.h>
>>> @@ -230,7 +231,28 @@ static int pmbus_probe(struct i2c_client *client,
>>> .id_table = pmbus_id,
>>> };
>>> -module_i2c_driver(pmbus_driver);
>>> +struct dentry *pmbus_debugfs_dir;
>>> +EXPORT_SYMBOL_GPL(pmbus_debugfs_dir);
>>> +
>>> +static int __init pmbus_init(void)
>>> +{
>>> + pmbus_debugfs_dir =
>>> debugfs_create_dir(pmbus_driver.driver.name, NULL);
>>> + if (IS_ERR(pmbus_debugfs_dir))
>>> + /* Don't fail out if we don't have debugfs support. */
>>> + pmbus_debugfs_dir = NULL;
>>> +
>>> + return i2c_add_driver(&pmbus_driver);
>>> +}
>>> +
>>> +static void __exit pmbus_exit(void)
>>> +{
>>> + debugfs_remove_recursive(pmbus_debugfs_dir);
>>> +
>>> + i2c_del_driver(&pmbus_driver);
>>> +}
>>> +
>>> +module_init(pmbus_init);
>>> +module_exit(pmbus_exit);
>>> MODULE_AUTHOR("Guenter Roeck");
>>> MODULE_DESCRIPTION("Generic PMBus driver");
>>> diff --git a/drivers/hwmon/pmbus/pmbus.h b/drivers/hwmon/pmbus/pmbus.h
>>> index bfcb13b..c772b83 100644
>>> --- a/drivers/hwmon/pmbus/pmbus.h
>>> +++ b/drivers/hwmon/pmbus/pmbus.h
>>> @@ -25,6 +25,8 @@
>>> #include <linux/bitops.h>
>>> #include <linux/regulator/driver.h>
>>> +struct dentry;
>>> +
>>> /*
>>> * Registers
>>> */
>>> @@ -383,6 +385,12 @@ struct pmbus_driver_info {
>>> /* Regulator functionality, if supported by this chip driver. */
>>> int num_regulators;
>>> const struct regulator_desc *reg_desc;
>>> +
>>> + /*
>>> + * Controls whether or not to create debugfs entries for this
>>> driver's
>>> + * devices.
>>> + */
>>> + bool debugfs;
>>> };
>>> /* Regulator ops */
>>> @@ -401,6 +409,9 @@ struct pmbus_driver_info {
>>> .owner = THIS_MODULE, \
>>> }
>>> +/* Handle for debugfs directory */
>>> +extern struct dentry *pmbus_debugfs_dir;
>>> +
>>> /* Function declarations */
>>> void pmbus_clear_cache(struct i2c_client *client);
>>> diff --git a/drivers/hwmon/pmbus/pmbus_core.c
>>> b/drivers/hwmon/pmbus/pmbus_core.c
>>> index 1a51f8f..afbd364 100644
>>> --- a/drivers/hwmon/pmbus/pmbus_core.c
>>> +++ b/drivers/hwmon/pmbus/pmbus_core.c
>>> @@ -19,6 +19,7 @@
>>> * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
>>> */
>>> +#include <linux/debugfs.h>
>>> #include <linux/kernel.h>
>>> #include <linux/module.h>
>>> #include <linux/init.h>
>>> @@ -49,6 +50,9 @@
>>> #define PB_STATUS_FAN34_BASE (PB_STATUS_FAN_BASE + PMBUS_PAGES)
>>> #define PB_STATUS_TEMP_BASE (PB_STATUS_FAN34_BASE + PMBUS_PAGES)
>>> #define PB_STATUS_INPUT_BASE (PB_STATUS_TEMP_BASE + PMBUS_PAGES)
>>> +#define PB_STATUS_CML_BASE (PB_STATUS_INPUT_BASE + PMBUS_PAGES)
>>> +#define PB_STATUS_OTHER_BASE (PB_STATUS_CML_BASE + PMBUS_PAGES)
>>> +#define PB_STATUS_MFR_BASE (PB_STATUS_OTHER_BASE + PMBUS_PAGES)
>> We are not actively using those status registers, are we ?
>> I am a bit concerned that we'll continuously read those status registers
>> but don't do anything with it most of the time. Ultimately I'd prefer
>> to get rid of all caching, not more, since it gets quite expensive
>> on chips with many pages.
>>
>> Maybe just display uncached status register values in debugfs ?
>
> Sounds good.
>
>>
>>> #define PB_STATUS_VMON_BASE (PB_STATUS_INPUT_BASE + 1)
>>> #define PB_NUM_STATUS_REG (PB_STATUS_VMON_BASE + 1)
>>> @@ -101,6 +105,7 @@ struct pmbus_data {
>>> int num_attributes;
>>> struct attribute_group group;
>>> const struct attribute_group *groups[2];
>>> + struct dentry *debugfs; /* debugfs device directory */
>>> struct pmbus_sensor *sensors;
>>> @@ -119,6 +124,11 @@ struct pmbus_data {
>>> u8 currpage;
>>> };
>>> +struct pmbus_debugfs_entry {
>>> + struct device *dev;
>>> + int index;
>>> +};
>>> +
>>> void pmbus_clear_cache(struct i2c_client *client)
>>> {
>>> struct pmbus_data *data = i2c_get_clientdata(client);
>>> @@ -422,6 +432,19 @@ static struct pmbus_data
>>> *pmbus_update_device(struct device *dev)
>>> = _pmbus_read_byte_data(client, i,
>>> s->reg);
>>> }
>>> +
>>> + if (!data->debugfs)
>>> + continue;
>>> +
>>> + data->status[PB_STATUS_CML_BASE + i]
>>> + = _pmbus_read_byte_data(client, i,
>>> + PMBUS_STATUS_CML);
>>> + data->status[PB_STATUS_OTHER_BASE + i]
>>> + = _pmbus_read_byte_data(client, i,
>>> + PMBUS_STATUS_OTHER);
>>> + data->status[PB_STATUS_MFR_BASE + i]
>>> + = _pmbus_read_byte_data(client, i,
>>> + PMBUS_STATUS_MFR_SPECIFIC);
>>> }
>>> if (info->func[0] & PMBUS_HAVE_STATUS_INPUT)
>>> @@ -1891,6 +1914,151 @@ static int pmbus_regulator_register(struct
>>> pmbus_data *data)
>>> }
>>> #endif
>>> +static int pmbus_debugfs_get(void *data, u64 *val)
>>> +{
>>> + struct pmbus_debugfs_entry *entry = data;
>>> + struct pmbus_data *pdata = pmbus_update_device(entry->dev);
>>> +
>>> + *val = pdata->status[entry->index];
>>> +
>>> + return 0;
>>> +}
>>> +
>>> +DEFINE_DEBUGFS_ATTRIBUTE(pmbus_debugfs_ops8, pmbus_debugfs_get, NULL,
>>> + "0x%02llx\n");
>>> +DEFINE_DEBUGFS_ATTRIBUTE(pmbus_debugfs_ops16, pmbus_debugfs_get, NULL,
>>> + "0x%04llx\n");
>>> +
>>> +static int pmbus_init_debugfs(struct i2c_client *client,
>>> + struct pmbus_data *data)
>>> +{
>>> + int i, idx = 0;
>>> + struct dentry *dbg;
>>> + char name[PMBUS_NAME_SIZE];
>>> + struct pmbus_debugfs_entry *entries;
>>> +
>>> + /*
>>> + * Either user didn't request debugfs or debugfs is not enabled in
>>> + * kernel. Exit but don't throw an error in these cases.
>>> + */
>> Here might be the place to initialize pmbus_debugfs_dir
>> if it is not yet initialized.
>>
>>> + if (!data->info->debugfs || !pmbus_debugfs_dir)
>>> + return 0;
>>> +
>>> + /*
>>> + * Create the debugfs directory for this device. Use the hwmon
>>> device
>>> + * name to avoid conflicts (hwmon numbers are globally unique).
>>> + */
>>> + data->debugfs = debugfs_create_dir(dev_name(data->hwmon_dev),
>>> + pmbus_debugfs_dir);
>>> + if (IS_ERR_OR_NULL(data->debugfs)) {
>>> + data->debugfs = NULL;
>>> + return -ENODEV;
>>> + }
>>> +
>>> + /* Allocate the max possible entries we need. */
>>> + entries = devm_kzalloc(data->dev,
>>> + sizeof(*entries) * (data->info->pages * 10),
>>> + GFP_KERNEL);
>>> + if (!entries)
>>> + return -ENOMEM;
>>> +
>>> + for (i = 0; i < data->info->pages; ++i) {
>>> + /* check accessibility of status register if it's not page
>>> 0 */
>>> + if (!i || pmbus_check_status_register(client, i)) {
>>> + entries[idx].dev = data->hwmon_dev;
>>> + entries[idx].index = PB_STATUS_BASE + i;
>>> + snprintf(name, PMBUS_NAME_SIZE, "status%d", i);
>>> + dbg = debugfs_create_file(name, 0444, data->debugfs,
>>> + &entries[idx++],
>>> + &pmbus_debugfs_ops16);
>> What is the point of the dbg variable ?
>>
>>> + }
>>> +
>>> + if (data->info->func[i] & PMBUS_HAVE_STATUS_VOUT) {
>>> + entries[idx].dev = data->hwmon_dev;
>>> + entries[idx].index = PB_STATUS_VOUT_BASE + i;
>>> + snprintf(name, PMBUS_NAME_SIZE, "status%d_vout", i);
>>> + dbg = debugfs_create_file(name, 0444, data->debugfs,
>>> + &entries[idx++],
>>> + &pmbus_debugfs_ops8);
>>> + }
>>> +
>>> + if (data->info->func[i] & PMBUS_HAVE_STATUS_IOUT) {
>>> + entries[idx].dev = data->hwmon_dev;
>>> + entries[idx].index = PB_STATUS_IOUT_BASE + i;
>>> + snprintf(name, PMBUS_NAME_SIZE, "status%d_iout", i);
>>> + dbg = debugfs_create_file(name, 0444, data->debugfs,
>>> + &entries[idx++],
>>> + &pmbus_debugfs_ops8);
>>> + }
>>> +
>>> + if (data->info->func[i] & PMBUS_HAVE_STATUS_INPUT) {
>>> + entries[idx].dev = data->hwmon_dev;
>>> + entries[idx].index = PB_STATUS_INPUT_BASE + i;
>>> + snprintf(name, PMBUS_NAME_SIZE, "status%d_input", i);
>>> + dbg = debugfs_create_file(name, 0444, data->debugfs,
>>> + &entries[idx++],
>>> + &pmbus_debugfs_ops8);
>>> + }
>>> +
>>> + if (data->info->func[i] & PMBUS_HAVE_STATUS_TEMP) {
>>> + entries[idx].dev = data->hwmon_dev;
>>> + entries[idx].index = PB_STATUS_TEMP_BASE + i;
>>> + snprintf(name, PMBUS_NAME_SIZE, "status%d_temp", i);
>>> + dbg = debugfs_create_file(name, 0444, data->debugfs,
>>> + &entries[idx++],
>>> + &pmbus_debugfs_ops8);
>>> + }
>>> +
>>> + if (pmbus_check_byte_register(client, i, PMBUS_STATUS_CML)) {
>>> + entries[idx].dev = data->hwmon_dev;
>>> + entries[idx].index = PB_STATUS_CML_BASE + i;
>>> + snprintf(name, PMBUS_NAME_SIZE, "status%d_cml", i);
>>> + dbg = debugfs_create_file(name, 0444, data->debugfs,
>>> + &entries[idx++],
>>> + &pmbus_debugfs_ops8);
>>> + }
>>> +
>>> + if (pmbus_check_byte_register(client, i,
>>> PMBUS_STATUS_OTHER)) {
>>> + entries[idx].dev = data->hwmon_dev;
>>> + entries[idx].index = PB_STATUS_OTHER_BASE + i;
>>> + snprintf(name, PMBUS_NAME_SIZE, "status%d_other", i);
>>> + dbg = debugfs_create_file(name, 0444, data->debugfs,
>>> + &entries[idx++],
>>> + &pmbus_debugfs_ops8);
>>> + }
>>> +
>>> + if (pmbus_check_byte_register(client, i,
>>> + PMBUS_STATUS_MFR_SPECIFIC)) {
>>> + entries[idx].dev = data->hwmon_dev;
>>> + entries[idx].index = PB_STATUS_MFR_BASE + i;
>>> + snprintf(name, PMBUS_NAME_SIZE, "status%d_mfr", i);
>>> + dbg = debugfs_create_file(name, 0444, data->debugfs,
>>> + &entries[idx++],
>>> + &pmbus_debugfs_ops8);
>>> + }
>>> +
>>> + if (data->info->func[i] & PMBUS_HAVE_STATUS_FAN12) {
>>> + entries[idx].dev = data->hwmon_dev;
>>> + entries[idx].index = PB_STATUS_FAN_BASE + i;
>>> + snprintf(name, PMBUS_NAME_SIZE, "status%d_fan12", i);
>>> + dbg = debugfs_create_file(name, 0444, data->debugfs,
>>> + &entries[idx++],
>>> + &pmbus_debugfs_ops8);
>>> + }
>>> +
>>> + if (data->info->func[i] & PMBUS_HAVE_STATUS_FAN34) {
>>> + entries[idx].dev = data->hwmon_dev;
>>> + entries[idx].index = PB_STATUS_FAN34_BASE + i;
>>> + snprintf(name, PMBUS_NAME_SIZE, "status%d_fan34", i);
>>> + dbg = debugfs_create_file(name, 0444, data->debugfs,
>>> + &entries[idx++],
>>> + &pmbus_debugfs_ops8);
>>> + }
>>> + }
>>> +
>>> + return 0;
>>> +}
>>> +
>> Typically debugfs code is conditional. What happens if DEBUGFS
>> is not enabled ? See below.
>>
>>> int pmbus_do_probe(struct i2c_client *client, const struct
>>> i2c_device_id *id,
>>> struct pmbus_driver_info *info)
>>> {
>>> @@ -1950,6 +2118,10 @@ int pmbus_do_probe(struct i2c_client *client,
>>> const struct i2c_device_id *id,
>>> if (ret)
>>> goto out_unregister;
>>> + ret = pmbus_init_debugfs(client, data);
>>> + if (ret)
>>> + dev_warn(dev, "Failed to register debugfs\n");
>> I think this warning will be generated if debugfs is disabled.
>> We should not do that. Consider putting the debugfs code into
>> #fidef and have a dummy pmbus_init_debugfs() returning 0 if
>> it is disabled.
>
> Yes, good idea.
>
>>
>>> +
>>> return 0;
>>> out_unregister:
>>> @@ -1963,6 +2135,9 @@ int pmbus_do_probe(struct i2c_client *client,
>>> const struct i2c_device_id *id,
>>> int pmbus_do_remove(struct i2c_client *client)
>>> {
>>> struct pmbus_data *data = i2c_get_clientdata(client);
>>> +
>>> + debugfs_remove_recursive(data->debugfs);
>>> +
>>> hwmon_device_unregister(data->hwmon_dev);
>>> kfree(data->group.attrs);
>>> return 0;
>>> --
>>> 1.8.3.1
>>>
>>> --
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>
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