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Subject[PATCH v3] platform/chrome: mfd/cros_ec_debugfs: Add debugfs entry to retrieve EC uptime.
Date
From: Tim Wawrzynczak <twawrzynczak@chromium.org>

The new debugfs entry 'uptime' is being made available to userspace so that
a userspace daemon can synchronize EC logs with host time.

Signed-off-by: Tim Wawrzynczak <twawrzynczak@chromium.org>
---
Changelist:
- Moved uptime file from sysfs to debugfs (/sys/kernel/debug/cros_ec/uptime)
- Fixed ordering of local variables in cros_ec_uptime_read.
Tested against ChromeOS kernel v4.14
---
Documentation/ABI/testing/debugfs-cros-ec | 10 +++++
drivers/platform/chrome/cros_ec_debugfs.c | 54 +++++++++++++++++++++++
2 files changed, 64 insertions(+)
create mode 100644 Documentation/ABI/testing/debugfs-cros-ec

diff --git a/Documentation/ABI/testing/debugfs-cros-ec b/Documentation/ABI/testing/debugfs-cros-ec
new file mode 100644
index 000000000000..24b781c67a4c
--- /dev/null
+++ b/Documentation/ABI/testing/debugfs-cros-ec
@@ -0,0 +1,10 @@
+What: /sys/kernel/debug/cros_ec/uptime
+Date: March 2019
+KernelVersion: 5.1
+Description:
+ Read-only.
+ Reads the EC's current uptime information
+ (using EC_CMD_GET_UPTIME_INFO) and prints
+ time_since_ec_boot_ms into the file.
+ This is used for synchronizing AP host time
+ with the cros_ec log.
diff --git a/drivers/platform/chrome/cros_ec_debugfs.c b/drivers/platform/chrome/cros_ec_debugfs.c
index 71308766e891..3ea42008a59e 100644
--- a/drivers/platform/chrome/cros_ec_debugfs.c
+++ b/drivers/platform/chrome/cros_ec_debugfs.c
@@ -201,6 +201,40 @@ static int cros_ec_console_log_release(struct inode *inode, struct file *file)
return 0;
}

+static ssize_t cros_ec_uptime_read(struct file *file,
+ char __user *user_buf,
+ size_t count,
+ loff_t *ppos)
+{
+ struct cros_ec_debugfs *debug_info = file->private_data;
+ struct cros_ec_device *ec_dev = debug_info->ec->ec_dev;
+ struct {
+ struct cros_ec_command msg;
+ struct ec_response_uptime_info resp;
+ } __packed ec_buf;
+ struct ec_response_uptime_info *resp;
+ struct cros_ec_command *msg;
+ char read_buf[32];
+ int ret;
+
+ msg = &ec_buf.msg;
+ resp = (struct ec_response_uptime_info *)msg->data;
+
+ msg->command = EC_CMD_GET_UPTIME_INFO;
+ msg->version = 0;
+ msg->insize = sizeof(*resp);
+ msg->outsize = 0;
+
+ ret = cros_ec_cmd_xfer_status(ec_dev, msg);
+ if (ret < 0)
+ return ret;
+
+ ret = scnprintf(read_buf, sizeof(read_buf), "%u\n",
+ resp->time_since_ec_boot_ms);
+
+ return simple_read_from_buffer(user_buf, count, ppos, read_buf, ret);
+}
+
static ssize_t cros_ec_pdinfo_read(struct file *file,
char __user *user_buf,
size_t count,
@@ -269,6 +303,13 @@ const struct file_operations cros_ec_pdinfo_fops = {
.llseek = default_llseek,
};

+const struct file_operations cros_ec_uptime_fops = {
+ .owner = THIS_MODULE,
+ .open = simple_open,
+ .read = cros_ec_uptime_read,
+ .llseek = default_llseek,
+};
+
static int ec_read_version_supported(struct cros_ec_dev *ec)
{
struct ec_params_get_cmd_versions_v1 *params;
@@ -413,6 +454,15 @@ static int cros_ec_create_pdinfo(struct cros_ec_debugfs *debug_info)
return 0;
}

+static int cros_ec_create_uptime(struct cros_ec_debugfs *debug_info)
+{
+ if (!debugfs_create_file("uptime", 0444, debug_info->dir, debug_info,
+ &cros_ec_uptime_fops))
+ return -ENOMEM;
+
+ return 0;
+}
+
static int cros_ec_debugfs_probe(struct platform_device *pd)
{
struct cros_ec_dev *ec = dev_get_drvdata(pd->dev.parent);
@@ -442,6 +492,10 @@ static int cros_ec_debugfs_probe(struct platform_device *pd)
if (ret)
goto remove_log;

+ ret = cros_ec_create_uptime(debug_info);
+ if (ret)
+ goto remove_log;
+
ec->debug_info = debug_info;

dev_set_drvdata(&pd->dev, ec);
--
2.20.1
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