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Date: Thu, 11 Jan 2018 10:23:36 -0600
From: Eddie James <eajames@...ux.vnet.ibm.com>
To: Guenter Roeck <linux@...ck-us.net>
Cc: linux-hwmon@...r.kernel.org, linux-kernel@...r.kernel.org,
jdelvare@...e.com, joel@....id.au
Subject: Re: [PATCH v2] hwmon (pmbus): cffps: Add led class device for power
supply fault led
On 01/10/2018 12:16 PM, Guenter Roeck wrote:
> On Wed, Jan 10, 2018 at 11:29:43AM -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@...ux.vnet.ibm.com>
>> ---
>>
>> Changes since v1:
>> - move led registration into a separate function.
>> - improve comments.
>>
>> drivers/hwmon/pmbus/ibm-cffps.c | 99 +++++++++++++++++++++++++++++++++++++----
>> 1 file changed, 91 insertions(+), 8 deletions(-)
>>
>> diff --git a/drivers/hwmon/pmbus/ibm-cffps.c b/drivers/hwmon/pmbus/ibm-cffps.c
>> index 2d6f4f4..cd9f685 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 +268,69 @@ 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 void ibm_cffps_create_led_class(size_t name_size, struct ibm_cffps *psu)
>> +{
>> + int rc;
>> + struct i2c_client *client = psu->client;
>> + struct device *dev = &client->dev;
>> + char *led_name = (void *)(&psu[1]);
>> +
> I really dislike this hack. Why not allocate a sufficient
> fixed length, say, 32 bytes, and just use it ? If you want
> to be really wasteful, use 48 or 64 bytes; that is still better
> than this code.
That's fair, I found this trick in some sony hid driver, but fixed
length is much cleaner.
>
>> + snprintf(led_name, name_size, "%s-%x", client->name, client->addr);
> %02x, maybe ? Your call, though.
>
> Thanks,
> Guenter
>
>> + 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(dev, &psu->led);
>> + if (rc)
>> + dev_warn(dev, "failed to register led class: %d\n", rc);
>> +}
>> +
>> static struct pmbus_driver_info ibm_cffps_info = {
>> .pages = 1,
>> .func[0] = PMBUS_HAVE_VIN | PMBUS_HAVE_VOUT | PMBUS_HAVE_IOUT |
>> @@ -277,6 +350,7 @@ static int ibm_cffps_probe(struct i2c_client *client,
>> const struct i2c_device_id *id)
>> {
>> int i, rc;
>> + size_t name_size;
>> struct dentry *debugfs;
>> struct dentry *ibm_cffps_dir;
>> struct ibm_cffps *psu;
>> @@ -286,6 +360,23 @@ static int ibm_cffps_probe(struct i2c_client *client,
>> if (rc)
>> return rc;
>>
>> + /* client name, '-', 8 chars for addr, and null terminator */
>> + name_size = strlen(client->name) + 10;
>> +
>> + /*
>> + * Don't fail the probe if there isn't enough memory for leds and
>> + * debugfs.
>> + */
>> + psu = devm_kzalloc(&client->dev, sizeof(*psu) + name_size, GFP_KERNEL);
>> + if (!psu)
>> + return 0;
>> +
>> + psu->client = client;
>> + mutex_init(&psu->input_history.update_lock);
>> + psu->input_history.last_update = jiffies - HZ;
>> +
>> + ibm_cffps_create_led_class(name_size, psu);
>> +
>> /* Don't fail the probe if we can't create debugfs */
>> debugfs = pmbus_get_debugfs_dir(client);
>> if (!debugfs)
>> @@ -295,14 +386,6 @@ 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;
>> -
>> for (i = 0; i < CFFPS_DEBUGFS_NUM_ENTRIES; ++i)
>> psu->debugfs_entries[i] = i;
>>
>> --
>> 1.8.3.1
>>
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