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Subject: Re: [PATCH v6 2/2] hwmon: (ucd9000) Add debugfs attributes to provide
 mfr_status
To:     Guenter Roeck <linux@roeck-us.net>
Cc:     linux-hwmon@vger.kernel.org, linux-kernel@vger.kernel.org,
        jdelvare@suse.com, joel@jms.id.au,
        Christopher Bostic <cbostic@linux.vnet.ibm.com>,
        Andrew Jeffery <andrew@aj.id.au>
References: <1521228359-32396-1-git-send-email-eajames@linux.vnet.ibm.com>
 <1521228359-32396-3-git-send-email-eajames@linux.vnet.ibm.com>
 <20180316195953.GA2470@roeck-us.net>
From:   Eddie James <eajames@linux.vnet.ibm.com>
Date:   Fri, 16 Mar 2018 15:04:47 -0500
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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 <cbostic@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 <cbostic@linux.vnet.ibm.com>
>> Signed-off-by: Andrew Jeffery <andrew@aj.id.au>
>> Signed-off-by: Eddie James <eajames@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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