Subject: Re: [PATCH] hwmon (pmbus): cffps: Add led class device for power
 supply fault led
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
References: <1515535524-27458-1-git-send-email-eajames@linux.vnet.ibm.com>
 <20180109225042.GB26819@roeck-us.net>
From: Eddie James <eajames@linux.vnet.ibm.com>
Date: Wed, 10 Jan 2018 10:36:56 -0600
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On 01/09/2018 04:50 PM, Guenter Roeck wrote:
> On Tue, Jan 09, 2018 at 04:05:24PM -0600, Eddie James wrote:
>> This power supply device doesn't correctly manage it's own fault led.
>> Add an led class device and register it so that userspace can manage
>> power supply fault led as necessary.
>>
>> Signed-off-by: Eddie James <eajames@linux.vnet.ibm.com>
>> ---
>>   drivers/hwmon/pmbus/ibm-cffps.c | 90 +++++++++++++++++++++++++++++++++++++----
>>   1 file changed, 82 insertions(+), 8 deletions(-)
>>
>> diff --git a/drivers/hwmon/pmbus/ibm-cffps.c b/drivers/hwmon/pmbus/ibm-cffps.c
>> index 2d6f4f4..1e95dea 100644
>> --- a/drivers/hwmon/pmbus/ibm-cffps.c
>> +++ b/drivers/hwmon/pmbus/ibm-cffps.c
>> @@ -13,6 +13,7 @@
>>   #include <linux/fs.h>
>>   #include <linux/i2c.h>
>>   #include <linux/jiffies.h>
>> +#include <linux/leds.h>
>>   #include <linux/module.h>
>>   #include <linux/mutex.h>
>>   #include <linux/pmbus.h>
>> @@ -25,6 +26,7 @@
>>   #define CFFPS_CCIN_CMD				0xBD
>>   #define CFFPS_FW_CMD_START			0xFA
>>   #define CFFPS_FW_NUM_BYTES			4
>> +#define CFFPS_SYS_CONFIG_CMD			0xDA
>>   
>>   #define CFFPS_INPUT_HISTORY_CMD			0xD6
>>   #define CFFPS_INPUT_HISTORY_SIZE		100
>> @@ -39,6 +41,11 @@
>>   #define CFFPS_MFR_VAUX_FAULT			BIT(6)
>>   #define CFFPS_MFR_CURRENT_SHARE_WARNING		BIT(7)
>>   
>> +#define CFFPS_LED_BLINK				BIT(0)
>> +#define CFFPS_LED_ON				BIT(1)
>> +#define CFFPS_LED_OFF				BIT(2)
>> +#define CFFPS_BLINK_RATE_MS			250
>> +
>>   enum {
>>   	CFFPS_DEBUGFS_INPUT_HISTORY = 0,
>>   	CFFPS_DEBUGFS_FRU,
>> @@ -63,6 +70,9 @@ struct ibm_cffps {
>>   	struct ibm_cffps_input_history input_history;
>>   
>>   	int debugfs_entries[CFFPS_DEBUGFS_NUM_ENTRIES];
>> +
>> +	u8 led_state;
>> +	struct led_classdev led;
>>   };
>>   
>>   #define to_psu(x, y) container_of((x), struct ibm_cffps, debugfs_entries[(y)])
>> @@ -258,6 +268,51 @@ static int ibm_cffps_read_word_data(struct i2c_client *client, int page,
>>   	return rc;
>>   }
>>   
>> +static void ibm_cffps_led_brightness_set(struct led_classdev *led_cdev,
>> +					 enum led_brightness brightness)
>> +{
>> +	int rc;
>> +	struct ibm_cffps *psu = container_of(led_cdev, struct ibm_cffps, led);
>> +
>> +	if (brightness == LED_OFF) {
>> +		psu->led_state = CFFPS_LED_OFF;
>> +	} else {
>> +		brightness = LED_FULL;
>> +		if (psu->led_state != CFFPS_LED_BLINK)
>> +			psu->led_state = CFFPS_LED_ON;
>> +	}
>> +
>> +	rc = i2c_smbus_write_byte_data(psu->client, CFFPS_SYS_CONFIG_CMD,
>> +				       psu->led_state);
>> +	if (rc < 0)
>> +		return;
>> +
>> +	led_cdev->brightness = brightness;
>> +}
>> +
>> +static int ibm_cffps_led_blink_set(struct led_classdev *led_cdev,
>> +				   unsigned long *delay_on,
>> +				   unsigned long *delay_off)
>> +{
>> +	int rc;
>> +	struct ibm_cffps *psu = container_of(led_cdev, struct ibm_cffps, led);
>> +
>> +	psu->led_state = CFFPS_LED_BLINK;
>> +
>> +	if (led_cdev->brightness == LED_OFF)
>> +		return 0;
>> +
>> +	rc = i2c_smbus_write_byte_data(psu->client, CFFPS_SYS_CONFIG_CMD,
>> +				       CFFPS_LED_BLINK);
>> +	if (rc < 0)
>> +		return rc;
>> +
>> +	*delay_on = CFFPS_BLINK_RATE_MS;
>> +	*delay_off = CFFPS_BLINK_RATE_MS;
>> +
>> +	return 0;
>> +}
>> +
>>   static struct pmbus_driver_info ibm_cffps_info = {
>>   	.pages = 1,
>>   	.func[0] = PMBUS_HAVE_VIN | PMBUS_HAVE_VOUT | PMBUS_HAVE_IOUT |
>> @@ -277,6 +332,8 @@ static int ibm_cffps_probe(struct i2c_client *client,
>>   			   const struct i2c_device_id *id)
>>   {
>>   	int i, rc;
>> +	char *led_name;
>> +	size_t name_length;
>>   	struct dentry *debugfs;
>>   	struct dentry *ibm_cffps_dir;
>>   	struct ibm_cffps *psu;
>> @@ -286,6 +343,31 @@ static int ibm_cffps_probe(struct i2c_client *client,
>>   	if (rc)
>>   		return rc;
>>   
>> +	/* client name, '-', 8 chars for addr, and null */
>> +	name_length = strlen(client->name) + 10;
>> +
>> +	/* Don't fail the probe if we can't create led devices */
>> +	psu = devm_kzalloc(&client->dev, sizeof(*psu) + name_length,
>> +			   GFP_KERNEL);
>> +	if (!psu)
>> +		return 0;
> ... and no debugfs either ?

Well we need that struct allocated for debugfs as well. I'll clarify the 
comment.

>
>> +
>> +	psu->client = client;
>> +	mutex_init(&psu->input_history.update_lock);
>> +	psu->input_history.last_update = jiffies - HZ;
>> +
>> +	led_name = (void *)(&psu[1]);
>> +	snprintf(led_name, name_length, "%s-%x", client->name, client->addr);
>> +	psu->led.name = led_name;
>> +	psu->led.max_brightness = LED_FULL;
>> +	psu->led.brightness_set = ibm_cffps_led_brightness_set;
>> +	psu->led.blink_set = ibm_cffps_led_blink_set;
>> +
>> +	rc = devm_led_classdev_register(&client->dev, &psu->led);
>> +	if (rc)
>> +		dev_info(&client->dev, "failed to register led class: %d\n",
> dev_warn() might be more appropriate.

Sure.

>
>> +			 rc);
>> +
> Please move the led initialization code into its own function.

Sure.

>
>>   	/* Don't fail the probe if we can't create debugfs */
>>   	debugfs = pmbus_get_debugfs_dir(client);
>>   	if (!debugfs)
>> @@ -295,14 +377,6 @@ static int ibm_cffps_probe(struct i2c_client *client,
>>   	if (!ibm_cffps_dir)
>>   		return 0;
>>   
>> -	psu = devm_kzalloc(&client->dev, sizeof(*psu), GFP_KERNEL);
>> -	if (!psu)
>> -		return 0;
>> -
>> -	psu->client = client;
>> -	mutex_init(&psu->input_history.update_lock);
>> -	psu->input_history.last_update = jiffies - HZ;
>> -
> unrelated ?

Thought it made sense to move it with the allocation, but I can leave it 
where it is.

Thanks,
Eddie

>
>>   	for (i = 0; i < CFFPS_DEBUGFS_NUM_ENTRIES; ++i)
>>   		psu->debugfs_entries[i] = i;
>>   
>> -- 
>> 1.8.3.1
>>