[PATCH linux dev-4.10 2/2] hwmon: (pmbus): cffps: Add input_history debugfs file

[Eddie James]

From: "Edward A. James" <eajames at us.ibm.com>

Provide binary data of the powers supply input history to debugfs.

Signed-off-by: Edward A. James <eajames at us.ibm.com>
---
 drivers/hwmon/pmbus/ibm-cffps.c | 97 ++++++++++++++++++++++++++++++++++++++++-
 1 file changed, 96 insertions(+), 1 deletion(-)

diff --git a/drivers/hwmon/pmbus/ibm-cffps.c b/drivers/hwmon/pmbus/ibm-cffps.c
index 1a6294c..0570c12 100644
--- a/drivers/hwmon/pmbus/ibm-cffps.c
+++ b/drivers/hwmon/pmbus/ibm-cffps.c
@@ -7,13 +7,19 @@
  * (at your option) any later version.
  */
 
+#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_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 +30,70 @@
 #define CFFPS_MFR_VAUX_FAULT			BIT(6)
 #define CFFPS_MFR_CURRENT_SHARE_WARNING		BIT(7)
 
+struct ibm_cffps {
+	struct i2c_client *client;
+
+	struct mutex update_lock;
+	unsigned long last_updated;
+
+	u8 byte_count;
+	u8 input_history[CFFPS_INPUT_HISTORY_SIZE];
+};
+
+static ssize_t ibm_cffps_read_input_history(struct file *file,
+					    char __user *buf, size_t count,
+					    loff_t *ppos)
+{
+	int rc;
+	struct ibm_cffps *psu = file->private_data;
+	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->update_lock);
+		if (time_after(jiffies, psu->last_updated + 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->update_lock);
+				return rc;
+			}
+
+			psu->byte_count = msgbuf1[0];
+			memcpy(psu->input_history, &msgbuf1[1],
+			       CFFPS_INPUT_HISTORY_SIZE);
+			psu->last_updated = jiffies;
+		}
+
+		mutex_unlock(&psu->update_lock);
+	}
+
+	return simple_read_from_buffer(buf, count, ppos, psu->input_history,
+				       psu->byte_count);
+}
+
+static const struct file_operations ibm_cffps_fops = {
+	.llseek = noop_llseek,
+	.read = ibm_cffps_read_input_history,
+	.open = simple_open,
+};
+
 static int ibm_cffps_read_byte_data(struct i2c_client *client, int page,
 				    int reg)
 {
@@ -119,7 +189,32 @@ 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 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->update_lock);
+	if (jiffies > HZ)
+		psu->last_updated = jiffies - HZ;
+
+	debugfs = pmbus_get_debugfs_dir(client);
+	if (!debugfs)
+		return 0;
+
+	debugfs_create_file("ibm_cffps_input_history", 0444, debugfs, psu,
+			    &ibm_cffps_fops);
+
+	return 0;
 }
 
 static const struct i2c_device_id ibm_cffps_id[] = {
-- 
1.8.3.1