Re: [PATCH v2] hwmon (pmbus): cffps: Add led class device for power supply fault led

From: Eddie James
Date: Thu Jan 11 2018 - 11:23:54 EST



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@xxxxxxxxxxxxxxxxxx>
---

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