On 08/10/2017 02:57 PM, Eddie James wrote:
From: "Edward A. James" <eaja...@us.ibm.com>

Export all the available status registers through debugfs, if the client
driver wants them.

Signed-off-by: Edward A. James <eaja...@us.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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