Re: [PATCH 2/2] hwmon (pmbus): cffps: Add debugfs entries

From: Eddie James
Date: Thu Dec 07 2017 - 17:19:58 EST



On 12/07/2017 02:53 PM, Guenter Roeck wrote:
On Thu, Dec 07, 2017 at 01:50:38PM -0600, Eddie James wrote:
From: "Edward A. James" <eajames@xxxxxxxxxx>

Add debugfs entries for additional power supply data, including part
number, serial number, FRU number, firmware revision, ccin, and the
input history of the power supply. The input history is 10 minutes of
input power data in the form of twenty 30-second packets. Each packet
contains average and maximum power for that 30 second period.

Signed-off-by: Edward A. James <eajames@xxxxxxxxxx>
---
drivers/hwmon/pmbus/ibm-cffps.c | 199 +++++++++++++++++++++++++++++++++++++++-
1 file changed, 198 insertions(+), 1 deletion(-)

diff --git a/drivers/hwmon/pmbus/ibm-cffps.c b/drivers/hwmon/pmbus/ibm-cffps.c
index cb56da6..6d19399 100644
--- a/drivers/hwmon/pmbus/ibm-cffps.c
+++ b/drivers/hwmon/pmbus/ibm-cffps.c
@@ -8,12 +8,26 @@
*/
#include <linux/bitops.h>
+#include <linux/debugfs.h>
#include <linux/device.h>
+#include <linux/fs.h>
#include <linux/i2c.h>
+#include <linux/jiffies.h>
#include <linux/module.h>
+#include <linux/mutex.h>
#include "pmbus.h"
+#define CFFPS_FRU_CMD 0x9A
+#define CFFPS_PN_CMD 0x9B
+#define CFFPS_SN_CMD 0x9E
+#define CFFPS_CCIN_CMD 0xBD
+#define CFFPS_FW_CMD_START 0xFA
+#define CFFPS_FW_NUM_BYTES 4
+
+#define CFFPS_INPUT_HISTORY_CMD 0xD6
+#define CFFPS_INPUT_HISTORY_SIZE 100
+
/* STATUS_MFR_SPECIFIC bits */
#define CFFPS_MFR_FAN_FAULT BIT(0)
#define CFFPS_MFR_THERMAL_FAULT BIT(1)
@@ -24,6 +38,144 @@
#define CFFPS_MFR_VAUX_FAULT BIT(6)
#define CFFPS_MFR_CURRENT_SHARE_WARNING BIT(7)
+enum {
+ CFFPS_DEBUGFS_INPUT_HISTORY = 0,
+ CFFPS_DEBUGFS_FRU,
+ CFFPS_DEBUGFS_PN,
+ CFFPS_DEBUGFS_SN,
+ CFFPS_DEBUGFS_CCIN,
+ CFFPS_DEBUGFS_FW,
+ CFFPS_DEBUGFS_NUM_ENTRIES
+};
+
+struct ibm_cffps_input_history {
+ struct mutex update_lock;
+ unsigned long last_update;
+
+ u8 byte_count;
+ u8 data[CFFPS_INPUT_HISTORY_SIZE];
+};
+
+struct ibm_cffps {
+ struct i2c_client *client;
+
+ struct ibm_cffps_input_history input_history;
+
+ int debugfs_entries[CFFPS_DEBUGFS_NUM_ENTRIES];
+};
+
+#define to_psu(x, y) container_of((x), struct ibm_cffps, debugfs_entries[(y)])
+
+static ssize_t ibm_cffps_read_input_history(struct ibm_cffps *psu,
+ char __user *buf, size_t count,
+ loff_t *ppos)
+{
+ int rc;
+ u8 msgbuf0[1] = { CFFPS_INPUT_HISTORY_CMD };
+ u8 msgbuf1[CFFPS_INPUT_HISTORY_SIZE + 1] = { 0 };
+ struct i2c_msg msg[2] = {
+ {
+ .addr = psu->client->addr,
+ .flags = psu->client->flags,
+ .len = 1,
+ .buf = msgbuf0,
+ }, {
+ .addr = psu->client->addr,
+ .flags = psu->client->flags | I2C_M_RD,
+ .len = CFFPS_INPUT_HISTORY_SIZE + 1,
+ .buf = msgbuf1,
+ },
+ };
+
+ if (!*ppos) {
+ mutex_lock(&psu->input_history.update_lock);
+ if (time_after(jiffies, psu->input_history.last_update + HZ)) {
+ /*
+ * Use a raw i2c transfer, since we need more bytes
+ * than Linux I2C supports through smbus xfr (only 32).
+ */
+ rc = i2c_transfer(psu->client->adapter, msg, 2);
+ if (rc < 0) {
+ mutex_unlock(&psu->input_history.update_lock);
+ return rc;
+ }
+
+ psu->input_history.byte_count = msgbuf1[0];
+ memcpy(psu->input_history.data, &msgbuf1[1],
+ CFFPS_INPUT_HISTORY_SIZE);
+ psu->input_history.last_update = jiffies;
+ }
+
+ mutex_unlock(&psu->input_history.update_lock);
+ }
+
+ return simple_read_from_buffer(buf, count, ppos,
+ psu->input_history.data,
+ psu->input_history.byte_count);
+}
+
+static ssize_t ibm_cffps_debugfs_op(struct file *file, char __user *buf,
+ size_t count, loff_t *ppos)
+{
+ u8 cmd;
+ int i, rc;
+ int *idxp = file->private_data;
+ int idx = *idxp;
+ struct ibm_cffps *psu = to_psu(idxp, idx);
+ char data[I2C_SMBUS_BLOCK_MAX] = { 0 };
+
+ switch (idx) {
+ case CFFPS_DEBUGFS_INPUT_HISTORY:
+ return ibm_cffps_read_input_history(psu, buf, count, ppos);
+ case CFFPS_DEBUGFS_FRU:
+ cmd = CFFPS_FRU_CMD;
+ break;
+ case CFFPS_DEBUGFS_PN:
+ cmd = CFFPS_PN_CMD;
+ break;
+ case CFFPS_DEBUGFS_SN:
+ cmd = CFFPS_SN_CMD;
+ break;
+ case CFFPS_DEBUGFS_CCIN:
+ rc = i2c_smbus_read_word_data(psu->client, CFFPS_CCIN_CMD);
+ if (rc < 0)
+ return rc;
+
+ rc = snprintf(data, 5, "%04X", rc);
+ goto done;
+ case CFFPS_DEBUGFS_FW:
+ for (i = 0; i < CFFPS_FW_NUM_BYTES; ++i) {
+ rc = i2c_smbus_read_byte_data(psu->client,
+ CFFPS_FW_CMD_START + i);
+ if (rc < 0)
+ return rc;
+
+ snprintf(&data[i * 2], 3, "%02X", rc);
+ }
+
+ rc = i * 2;
+ goto done;
+ default:
+ return -EINVAL;
+ }
+
+ rc = i2c_smbus_read_block_data(psu->client, cmd, data);
+ if (rc < 0)
+ return rc;
+
+done:
+ data[rc] = '\n';
+ rc += 2;
+
+ return simple_read_from_buffer(buf, count, ppos, data, rc);
+}
+
+static const struct file_operations ibm_cffps_fops = {
+ .llseek = noop_llseek,
+ .read = ibm_cffps_debugfs_op,
+ .open = simple_open,
+};
+
static int ibm_cffps_read_byte_data(struct i2c_client *client, int page,
int reg)
{
@@ -119,7 +271,52 @@ static int ibm_cffps_read_word_data(struct i2c_client *client, int page,
static int ibm_cffps_probe(struct i2c_client *client,
const struct i2c_device_id *id)
{
- return pmbus_do_probe(client, id, &ibm_cffps_info);
+ int i, rc;
+ struct dentry *debugfs;
+ struct ibm_cffps *psu;
+
+ rc = pmbus_do_probe(client, id, &ibm_cffps_info);
+ if (rc)
+ return rc;
+
+ /* Don't fail the probe if we can't create debugfs */
+ psu = devm_kzalloc(&client->dev, sizeof(*psu), GFP_KERNEL);
+ if (!psu)
+ return 0;
+
+ psu->client = client;
+ mutex_init(&psu->input_history.update_lock);
+ if (jiffies > HZ)
+ /* time_after wouldn't succeed with last_update = 0 in test */
... but you are setting it to 'jiffies' elsewhere, so it can still end up
being 0 at some point, especially since 'jiffies' starts with a large number
and wraps a few minutes after boot. Not sure I understand the problem,
actually. Can you elaborate ?

Yea, not sure I understand it either, but basically, if we don't set last_update to jiffies - HZ or similar at start up, the check above for time_after(jiffies, last_upate + HZ) doesn't succeed soon after the boot. This doesn't make any sense to me, unless time_after is broken, but setting last_update to something relative to jiffies during probe fixes it.

[Â 279.480000] failed time_after with jiffies[-2052] last_update[0]
[Â 302.050000] succeeded time_after with jiffies[205] last_update[0]

tested with this (should have used %u instead of %d, but you get the idea):

diff --git a/drivers/hwmon/pmbus/ibm-cffps.c b/drivers/hwmon/pmbus/ibm-cffps.c
index 6d19399..e5cb52a 100644
--- a/drivers/hwmon/pmbus/ibm-cffps.c
+++ b/drivers/hwmon/pmbus/ibm-cffps.c
@@ -90,6 +90,7 @@ static ssize_t ibm_cffps_read_input_history(struct ibm_cffps *psu,
ÂÂÂÂ if (!*ppos) {
ÂÂÂÂ ÂÂÂ mutex_lock(&psu->input_history.update_lock);
ÂÂÂÂ ÂÂÂ if (time_after(jiffies, psu->input_history.last_update + HZ)) {
+printk("succeeded time_after with jiffies[%d] last_update[%d]\n", jiffies, psu->input_history.last_update);
ÂÂÂÂ ÂÂÂ ÂÂÂ /*
ÂÂÂÂ ÂÂÂ ÂÂÂ Â* Use a raw i2c transfer, since we need more bytes
ÂÂÂÂ ÂÂÂ ÂÂÂ Â* than Linux I2C supports through smbus xfr (only 32).
@@ -105,6 +106,8 @@ static ssize_t ibm_cffps_read_input_history(struct ibm_cffps *psu,
ÂÂÂÂ ÂÂÂ ÂÂÂ ÂÂÂÂÂÂ CFFPS_INPUT_HISTORY_SIZE);
ÂÂÂÂ ÂÂÂ ÂÂÂ psu->input_history.last_update = jiffies;
ÂÂÂÂ ÂÂÂ }
+ÂÂÂ ÂÂÂ else
+printk("failed time_after with jiffies[%d] last_update[%d]\n", jiffies, psu->input_history.last_update);

ÂÂÂÂ ÂÂÂ mutex_unlock(&psu->input_history.update_lock);
ÂÂÂÂ }
@@ -286,9 +289,6 @@ static int ibm_cffps_probe(struct i2c_client *client,

ÂÂÂÂ psu->client = client;
ÂÂÂÂ mutex_init(&psu->input_history.update_lock);
-ÂÂÂ if (jiffies > HZ)
-ÂÂÂ ÂÂÂ /* time_after wouldn't succeed with last_update = 0 in test */
-ÂÂÂ ÂÂÂ psu->input_history.last_update = jiffies - HZ;

ÂÂÂÂ debugfs = pmbus_get_debugfs_dir(client);
ÂÂÂÂ if (!debugfs)
--



+ psu->input_history.last_update = jiffies - HZ;
+
+ debugfs = pmbus_get_debugfs_dir(client);
+ if (!debugfs)
+ return 0;
+
It might be better to do that first, to avoid allocating memory unnecessarily.
That memory would only be freed when the driver is unloaded.

True.


+ for (i = 0; i < CFFPS_DEBUGFS_NUM_ENTRIES; ++i)
+ psu->debugfs_entries[i] = i;
+
+ debugfs_create_file("ibm_cffps_input_history", 0444, debugfs,
+ &psu->debugfs_entries[CFFPS_DEBUGFS_INPUT_HISTORY],
+ &ibm_cffps_fops);
+ debugfs_create_file("ibm_cffps_fru", 0444, debugfs,
+ &psu->debugfs_entries[CFFPS_DEBUGFS_FRU],
+ &ibm_cffps_fops);
+ debugfs_create_file("ibm_cffps_pn", 0444, debugfs,
+ &psu->debugfs_entries[CFFPS_DEBUGFS_PN],
+ &ibm_cffps_fops);
+ debugfs_create_file("ibm_cffps_sn", 0444, debugfs,
+ &psu->debugfs_entries[CFFPS_DEBUGFS_SN],
+ &ibm_cffps_fops);
+ debugfs_create_file("ibm_cffps_ccin", 0444, debugfs,
+ &psu->debugfs_entries[CFFPS_DEBUGFS_CCIN],
+ &ibm_cffps_fops);
+ debugfs_create_file("ibm_cffps_fw", 0444, debugfs,
+ &psu->debugfs_entries[CFFPS_DEBUGFS_FW],
+ &ibm_cffps_fops);
Can you put those into their own subdirectory ?

.../ibm_cffps/input_history
.../ibm_cffps/fru

and so on. Also, consider using ibm_cffps1 (or client->name) to align
with the the hwmon 'name' attribute.

Good idea.

Thanks,
Eddie


Thanks,
Guenter

+
+ return 0;
}
static const struct i2c_device_id ibm_cffps_id[] = {
--
1.8.3.1