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Date: Wed, 10 Jan 2018 10:16:34 -0800
From: Guenter Roeck <linux@...ck-us.net>
To: Eddie James <eajames@...ux.vnet.ibm.com>
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 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.
> + 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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