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SubjectRe: [PATCH 2/2] hwmon (pmbus): cffps: Add debugfs entries
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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@us.ibm.com>
>>
>> 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@us.ibm.com>
>> ---
>> 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.

[  279.480000] failed time_after with jiffies[-2052] last_update[0]
[  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,
     if (!*ppos) {
         mutex_lock(&psu->input_history.update_lock);
         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);
             /*
              * Use a raw i2c transfer, since we need more bytes
              * 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,
                    CFFPS_INPUT_HISTORY_SIZE);
             psu->input_history.last_update = jiffies;
         }
+        else
+printk("failed time_after with jiffies[%d] last_update[%d]\n", jiffies,
psu->input_history.last_update);

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

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

     debugfs = pmbus_get_debugfs_dir(client);
     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
>>

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