by Guenter Roeck

[permalink] [raw]

Subject: Re: [PATCH 4/4] drivers/hwmon/pmbus: Add debugfs for status registers

On Thu, Aug 10, 2017 at 03:23:11PM -0500, Eddie James wrote:
>
>
> 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" <[email protected]>
> >>>
> >>>Export all the available status registers through debugfs, if the
> >>>client
> >>>driver wants them.
> >>>
> >>>Signed-off-by: Edward A. James <[email protected]>
> >>>---
> >>> 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.
>

nack. pmbus.c is logically completely different to pmbus_core.c, and doesn't
even have to be enabled.

Guenter

> >
> >>
> >>>@@ -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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> >>>in
> >>>the body of a message to [email protected]
> >>>More majordomo info at http://vger.kernel.org/majordomo-info.html
> >
>