Re: [PATCH v6 2/2] hwmon: (ucd9000) Add debugfs attributes to provide mfr_status

[Eddie James]

On 03/16/2018 02:59 PM, Guenter Roeck wrote:
On Fri, Mar 16, 2018 at 02:25:59PM -0500, Eddie James wrote:
From: Christopher Bostic <cbos...@linux.vnet.ibm.com>

Expose the gpiN_fault fields of mfr_status as individual debugfs
attributes. This provides a way for users to be easily notified of gpi
faults. Also provide the whole mfr_status register in debugfs.

Signed-off-by: Christopher Bostic <cbos...@linux.vnet.ibm.com>
Signed-off-by: Andrew Jeffery <and...@aj.id.au>
Signed-off-by: Eddie James <eaja...@linux.vnet.ibm.com>
---
  drivers/hwmon/pmbus/ucd9000.c | 138 +++++++++++++++++++++++++++++++++++++++++-
  1 file changed, 137 insertions(+), 1 deletion(-)

diff --git a/drivers/hwmon/pmbus/ucd9000.c b/drivers/hwmon/pmbus/ucd9000.c
index ef2c5bf..88c98fb 100644
--- a/drivers/hwmon/pmbus/ucd9000.c
+++ b/drivers/hwmon/pmbus/ucd9000.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/of_device.h>
@@ -37,6 +38,7 @@
  #define UCD9000_NUM_PAGES             0xd6
  #define UCD9000_FAN_CONFIG_INDEX      0xe7
  #define UCD9000_FAN_CONFIG            0xe8
+#define UCD9000_MFR_STATUS             0xf3
  #define UCD9000_GPIO_SELECT           0xfa
  #define UCD9000_GPIO_CONFIG           0xfb
  #define UCD9000_DEVICE_ID             0xfd
@@ -64,15 +66,24 @@
  #define UCD901XX_NUM_GPIOS    26
  #define UCD90910_NUM_GPIOS    26
  
+#define UCD9000_DEBUGFS_NAME_LEN	24
+#define UCD9000_GPI_COUNT              8
+
  struct ucd9000_data {
        u8 fan_data[UCD9000_NUM_FAN][I2C_SMBUS_BLOCK_MAX];
        struct pmbus_driver_info info;
  #ifdef CONFIG_GPIOLIB
        struct gpio_chip gpio;
  #endif
+       struct dentry *debugfs;
  };
  #define to_ucd9000_data(_info) container_of(_info, struct ucd9000_data, info)
  
+struct ucd9000_debugfs_entry {
+       struct i2c_client *client;
+       u8 index;
+};
+
  static int ucd9000_get_fan_config(struct i2c_client *client, int fan)
  {
        int fan_config = 0;
@@ -359,6 +370,122 @@ static void ucd9000_probe_gpio(struct i2c_client *client,
  }
  #endif /* CONFIG_GPIOLIB */
  
+#ifdef CONFIG_DEBUG_FS
+static int ucd9000_get_mfr_status(struct i2c_client *client, u8 *buffer)
+{
+       int ret = pmbus_set_page(client, 0);
+
+       if (ret < 0)
+               return ret;
+
+       return i2c_smbus_read_block_data(client, UCD9000_MFR_STATUS, buffer);
+}
+
+static int ucd9000_debugfs_show_mfr_status_bit(void *data, u64 *val)
+{
+       struct ucd9000_debugfs_entry *entry = data;
+       struct i2c_client *client = entry->client;
+       u8 buffer[I2C_SMBUS_BLOCK_MAX];
+       int ret;
+
+       ret = ucd9000_get_mfr_status(client, buffer);
+       if (ret < 0)
+               return ret;
+
+       /*
+        * Attribute only created for devices with gpi fault bits at bits
+        * 16-23, which is the second byte of the response.
+        */
+       *val = !!(buffer[1] & BIT(entry->index));
+
+       return 0;
+}
+DEFINE_DEBUGFS_ATTRIBUTE(ucd9000_debugfs_mfr_status_bit,
+                        ucd9000_debugfs_show_mfr_status_bit, NULL, "%1lld\n");
+
+static ssize_t ucd9000_debugfs_read_mfr_status(struct file *file,
+                                              char __user *buf, size_t count,
+                                              loff_t *ppos)
+{
+       struct i2c_client *client = file->private_data;
+       u8 buffer[I2C_SMBUS_BLOCK_MAX];
+       char str[(I2C_SMBUS_BLOCK_MAX * 2) + 2];
+       char *res;
+       int rc;
+
+       rc = ucd9000_get_mfr_status(client, buffer);
+       if (rc < 0)
+               return rc;
+
+       res = bin2hex(str, buffer, min(rc, I2C_SMBUS_BLOCK_MAX));
+       *res++ = '\n';
+       *res++ = 0;
+
Unless I am missing something, this now returns the terminating '\0'
to the user. Is this really what you want ?

Yes, that was my intention. I thought that was normal. It worked fine 
when I cat'ed the file. Up to you, I can change it if you like.

Thanks,
Eddie


I see other code adding the terminator, but it doesn't usually return it
to the user.

Guenter

+       return simple_read_from_buffer(buf, count, ppos, str, res - str);
+}
+
+static const struct file_operations ucd9000_debugfs_show_mfr_status_fops = {
+       .llseek = noop_llseek,
+       .read = ucd9000_debugfs_read_mfr_status,
+       .open = simple_open,
+};
+
+static int ucd9000_init_debugfs(struct i2c_client *client,
+                               const struct i2c_device_id *mid,
+                               struct ucd9000_data *data)
+{
+       struct dentry *debugfs;
+       struct ucd9000_debugfs_entry *entries;
+       int i;
+       char name[UCD9000_DEBUGFS_NAME_LEN];
+
+       debugfs = pmbus_get_debugfs_dir(client);
+       if (!debugfs)
+               return -ENOENT;
+
+       data->debugfs = debugfs_create_dir(client->name, debugfs);
+       if (!data->debugfs)
+               return -ENOENT;
+
+       /*
+        * Of the chips this driver supports, only the UCD9090, UCD90160,
+        * and UCD90910 report GPI faults in their MFR_STATUS register, so only
+        * create the GPI fault debugfs attributes for those chips.
+        */
+       if (mid->driver_data == ucd9090 || mid->driver_data == ucd90160 ||
+           mid->driver_data == ucd90910) {
+               entries = devm_kzalloc(&client->dev,
+                                      sizeof(*entries) * UCD9000_GPI_COUNT,
+                                      GFP_KERNEL);
+               if (!entries)
+                       return -ENOMEM;
+
+               for (i = 0; i < UCD9000_GPI_COUNT; i++) {
+                       entries[i].client = client;
+                       entries[i].index = i;
+                       scnprintf(name, UCD9000_DEBUGFS_NAME_LEN,
+                                 "gpi%d_alarm", i + 1);
+                       debugfs_create_file(name, 0444, data->debugfs,
+                                           &entries[i],
+                                           &ucd9000_debugfs_mfr_status_bit);
+               }
+       }
+
+       scnprintf(name, UCD9000_DEBUGFS_NAME_LEN, "mfr_status");
+       debugfs_create_file(name, 0444, data->debugfs, client,
+                           &ucd9000_debugfs_show_mfr_status_fops);
+
+       return 0;
+}
+#else
+static int ucd9000_init_debugfs(struct i2c_client *client,
+                               const struct i2c_device_id *mid,
+                               struct ucd9000_data *data)
+{
+       return 0;
+}
+#endif /* CONFIG_DEBUG_FS */
+
  static int ucd9000_probe(struct i2c_client *client,
                         const struct i2c_device_id *id)
  {
@@ -475,7 +602,16 @@ static int ucd9000_probe(struct i2c_client *client,
  
  	ucd9000_probe_gpio(client, mid, data);
  
-	return pmbus_do_probe(client, mid, info);
+       ret = pmbus_do_probe(client, mid, info);
+       if (ret)
+               return ret;
+
+       ret = ucd9000_init_debugfs(client, mid, data);
+       if (ret)
+               dev_warn(&client->dev, "Failed to register debugfs: %d\n",
+                        ret);
+
+       return 0;
  }
  
  /* This is the driver that will be inserted */
--
1.8.3.1

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