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Date: Fri, 11 Aug 2017 06:52:45 -0700
From: Guenter Roeck <linux@...ck-us.net>
To: Eddie James <eajames@...ux.vnet.ibm.com>
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 v2 4/4] hwmon: (pmbus): Add debugfs for status registers
On 08/10/2017 02:57 PM, 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.h | 6 ++
> drivers/hwmon/pmbus/pmbus_core.c | 201 +++++++++++++++++++++++++++++++++++++++
> 2 files changed, 207 insertions(+)
>
> diff --git a/drivers/hwmon/pmbus/pmbus.h b/drivers/hwmon/pmbus/pmbus.h
> index bfcb13b..5f91a19 100644
> --- a/drivers/hwmon/pmbus/pmbus.h
> +++ b/drivers/hwmon/pmbus/pmbus.h
> @@ -383,6 +383,12 @@ 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 */
> diff --git a/drivers/hwmon/pmbus/pmbus_core.c b/drivers/hwmon/pmbus/pmbus_core.c
> index ef135d8..b11ebec 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>
> @@ -101,6 +102,7 @@ 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;
>
> @@ -120,6 +122,12 @@ struct pmbus_data {
> u8 currpage;
> };
>
> +struct pmbus_debugfs_entry {
> + struct i2c_client *client;
> + u8 page;
> + u8 reg;
> +};
> +
> void pmbus_clear_cache(struct i2c_client *client)
> {
> struct pmbus_data *data = i2c_get_clientdata(client);
> @@ -1893,6 +1901,184 @@ static int pmbus_regulator_register(struct pmbus_data *data)
> }
> #endif
>
> +static struct dentry *pmbus_debugfs_dir; /* pmbus debugfs directory */
> +
> +#if IS_ENABLED(CONFIG_DEBUG_FS)
> +static int pmbus_debugfs_get(void *data, u64 *val)
> +{
> + struct pmbus_debugfs_entry *entry = data;
> +
> + *val = _pmbus_read_byte_data(entry->client, entry->page, entry->reg);
> +
> + return 0;
> +}
> +DEFINE_DEBUGFS_ATTRIBUTE(pmbus_debugfs_ops, pmbus_debugfs_get, NULL,
> + "0x%02llx\n");
> +
> +static int pmbus_debugfs_get_status(void *data, u64 *val)
> +{
> + struct pmbus_debugfs_entry *entry = data;
> + struct pmbus_data *pdata = i2c_get_clientdata(entry->client);
> +
> + *val = pdata->read_status(entry->client, entry->page);
> +
> + return 0;
> +}
> +DEFINE_DEBUGFS_ATTRIBUTE(pmbus_debugfs_ops_status, pmbus_debugfs_get_status,
> + NULL, "0x%04llx\n");
> +
> +static int pmbus_init_debugfs(struct i2c_client *client,
> + struct pmbus_data *data)
> +{
> + int i, idx = 0;
> + char name[PMBUS_NAME_SIZE];
> + struct pmbus_debugfs_entry *entries;
> +
> + /* Check if client driver requested debugfs support. */
> + if (!data->info->debugfs)
> + return 0;
> +
Let's just make this unconditional and drop the flag. I don't see the value
in enabling it per driver. The code is there anyway, might as well support it.
> + /* Create the root pmbus debugfs directory if it's not created yet. */
> + if (!pmbus_debugfs_dir) {
> + pmbus_debugfs_dir = debugfs_create_dir("pmbus", NULL);
> + if (IS_ERR_OR_NULL(pmbus_debugfs_dir)) {
> + pmbus_debugfs_dir = NULL;
> + return -ENODEV;
> + }
> + }
> +
> + /*
> + * 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)) {
> + /* No need to set reg as we have special read op. */
> + entries[idx].client = client;
> + entries[idx].page = i;
> + snprintf(name, PMBUS_NAME_SIZE, "status%d", i);
scnprintf might be better.
> + debugfs_create_file(name, 0444, data->debugfs,
> + &entries[idx++],
> + &pmbus_debugfs_ops_status);
> + }
> +
> + if (data->info->func[i] & PMBUS_HAVE_STATUS_VOUT) {
> + entries[idx].client = client;
> + entries[idx].page = i;
> + entries[idx].reg = PMBUS_STATUS_VOUT;
> + snprintf(name, PMBUS_NAME_SIZE, "status%d_vout", i);
> + debugfs_create_file(name, 0444, data->debugfs,
> + &entries[idx++],
> + &pmbus_debugfs_ops);
> + }
> +
> + if (data->info->func[i] & PMBUS_HAVE_STATUS_IOUT) {
> + entries[idx].client = client;
> + entries[idx].page = i;
> + entries[idx].reg = PMBUS_STATUS_IOUT;
> + snprintf(name, PMBUS_NAME_SIZE, "status%d_iout", i);
> + debugfs_create_file(name, 0444, data->debugfs,
> + &entries[idx++],
> + &pmbus_debugfs_ops);
> + }
> +
> + if (data->info->func[i] & PMBUS_HAVE_STATUS_INPUT) {
> + entries[idx].client = client;
> + entries[idx].page = i;
> + entries[idx].reg = PMBUS_STATUS_INPUT;
> + snprintf(name, PMBUS_NAME_SIZE, "status%d_input", i);
> + debugfs_create_file(name, 0444, data->debugfs,
> + &entries[idx++],
> + &pmbus_debugfs_ops);
> + }
> +
> + if (data->info->func[i] & PMBUS_HAVE_STATUS_TEMP) {
> + entries[idx].client = client;
> + entries[idx].page = i;
> + entries[idx].reg = PMBUS_STATUS_TEMPERATURE;
> + snprintf(name, PMBUS_NAME_SIZE, "status%d_temp", i);
> + debugfs_create_file(name, 0444, data->debugfs,
> + &entries[idx++],
> + &pmbus_debugfs_ops);
> + }
> +
> + if (pmbus_check_byte_register(client, i, PMBUS_STATUS_CML)) {
> + entries[idx].client = client;
> + entries[idx].page = i;
> + entries[idx].reg = PMBUS_STATUS_CML;
> + snprintf(name, PMBUS_NAME_SIZE, "status%d_cml", i);
> + debugfs_create_file(name, 0444, data->debugfs,
> + &entries[idx++],
> + &pmbus_debugfs_ops);
> + }
> +
> + if (pmbus_check_byte_register(client, i, PMBUS_STATUS_OTHER)) {
> + entries[idx].client = client;
> + entries[idx].page = i;
> + entries[idx].reg = PMBUS_STATUS_OTHER;
> + snprintf(name, PMBUS_NAME_SIZE, "status%d_other", i);
> + debugfs_create_file(name, 0444, data->debugfs,
> + &entries[idx++],
> + &pmbus_debugfs_ops);
> + }
> +
> + if (pmbus_check_byte_register(client, i,
> + PMBUS_STATUS_MFR_SPECIFIC)) {
> + entries[idx].client = client;
> + entries[idx].page = i;
> + entries[idx].reg = PMBUS_STATUS_MFR_SPECIFIC;
> + snprintf(name, PMBUS_NAME_SIZE, "status%d_mfr", i);
> + debugfs_create_file(name, 0444, data->debugfs,
> + &entries[idx++],
> + &pmbus_debugfs_ops);
> + }
> +
> + if (data->info->func[i] & PMBUS_HAVE_STATUS_FAN12) {
> + entries[idx].client = client;
> + entries[idx].page = i;
> + entries[idx].reg = PMBUS_STATUS_FAN_12;
> + snprintf(name, PMBUS_NAME_SIZE, "status%d_fan12", i);
> + debugfs_create_file(name, 0444, data->debugfs,
> + &entries[idx++],
> + &pmbus_debugfs_ops);
> + }
> +
> + if (data->info->func[i] & PMBUS_HAVE_STATUS_FAN34) {
> + entries[idx].client = client;
> + entries[idx].page = i;
> + entries[idx].reg = PMBUS_STATUS_FAN_34;
> + snprintf(name, PMBUS_NAME_SIZE, "status%d_fan34", i);
> + debugfs_create_file(name, 0444, data->debugfs,
> + &entries[idx++],
> + &pmbus_debugfs_ops);
> + }
> + }
> +
> + return 0;
> +}
> +#else
> +static int pmbus_init_debugfs(struct i2c_client *client,
> + struct pmbus_data *data)
> +{
> + return 0;
> +}
> +#endif /* IS_ENABLED(CONFIG_DEBUG_FS) */
> +
> int pmbus_do_probe(struct i2c_client *client, const struct i2c_device_id *id,
> struct pmbus_driver_info *info)
> {
> @@ -1952,6 +2138,10 @@ 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");
> +
> return 0;
>
> out_unregister:
> @@ -1965,6 +2155,17 @@ 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);
> + if (pmbus_debugfs_dir && simple_empty(pmbus_debugfs_dir)) {
Almost. Problem is that it is racy against insertions.
We would need a mutex to protect write accesses to pmbus_debugfs_dir.
Wonder if we can just add module_init/module_exit to pmbus_core.c
and initialize/remove the directory from there.
Guenter
> + /*
> + * Remove the root pmbus debugfs directory if we've removed
> + * all the device directories underneath already.
> + */
> + debugfs_remove(pmbus_debugfs_dir);
> + pmbus_debugfs_dir = NULL;
> + }
> +
> hwmon_device_unregister(data->hwmon_dev);
> kfree(data->group.attrs);
> return 0;
>
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