[PATCH 6/8] platform/chrome: cros_ec_chardev: Move data to chardev_pdata

Tzung-Bi Shih
2026-04-27T13:47:53Z

Move `ec_dev` and `cmd_offset` from `chardev_priv` to `chardev_pdata` as
they are per-device properties but not per-open-file properties.

Hold a reference to `chardev_pdata` for each open file to ensure the
data remains valid even if the underlying platform device is removed.

Signed-off-by: Tzung-Bi Shih <tzungbi@kernel.org>
---
drivers/platform/chrome/cros_ec_chardev.c | 36 +++++++++++++----------
1 file changed, 20 insertions(+), 16 deletions(-)

diff --git a/drivers/platform/chrome/cros_ec_chardev.c b/drivers/platform/chrome/cros_ec_chardev.c
index e7012e44a006..352d61a2f3c6 100644
--- a/drivers/platform/chrome/cros_ec_chardev.c
+++ b/drivers/platform/chrome/cros_ec_chardev.c
@@ -38,6 +38,8 @@
struct chardev_pdata {
struct miscdevice misc;
struct kref kref;
+ struct cros_ec_device *ec_dev;
+ u16 cmd_offset;
};

static void chardev_pdata_release(struct kref *kref)
@@ -48,13 +50,12 @@ static void chardev_pdata_release(struct kref *kref)
}

struct chardev_priv {
- struct cros_ec_device *ec_dev;
struct notifier_block notifier;
wait_queue_head_t wait_event;
unsigned long event_mask;
struct list_head events;
size_t event_len;
- u16 cmd_offset;
+ struct chardev_pdata *pdata;
};

struct ec_event {
@@ -77,10 +78,10 @@ static int ec_get_version(struct chardev_priv *priv, char *str, int maxlen)
if (!msg)
return -ENOMEM;

- msg->command = EC_CMD_GET_VERSION + priv->cmd_offset;
+ msg->command = EC_CMD_GET_VERSION + priv->pdata->cmd_offset;
msg->insize = sizeof(*resp);

- ret = cros_ec_cmd_xfer_status(priv->ec_dev, msg);
+ ret = cros_ec_cmd_xfer_status(priv->pdata->ec_dev, msg);
if (ret < 0) {
snprintf(str, maxlen,
"Unknown EC version, returned error: %d\n",
@@ -108,7 +109,7 @@ static int cros_ec_chardev_mkbp_event(struct notifier_block *nb,
{
struct chardev_priv *priv = container_of(nb, struct chardev_priv,
notifier);
- struct cros_ec_device *ec_dev = priv->ec_dev;
+ struct cros_ec_device *ec_dev = priv->pdata->ec_dev;
struct ec_event *event;
unsigned long event_bit = 1 << ec_dev->event_data.event_type;
int total_size = sizeof(*event) + ec_dev->event_size;
@@ -173,8 +174,7 @@ static struct ec_event *cros_ec_chardev_fetch_event(struct chardev_priv *priv,
static int cros_ec_chardev_open(struct inode *inode, struct file *filp)
{
struct miscdevice *mdev = filp->private_data;
- struct cros_ec_dev *ec = dev_get_drvdata(mdev->parent);
- struct cros_ec_device *ec_dev = ec->ec_dev;
+ struct chardev_pdata *pdata = container_of(mdev, typeof(*pdata), misc);
struct chardev_priv *priv;
int ret;

@@ -182,18 +182,20 @@ static int cros_ec_chardev_open(struct inode *inode, struct file *filp)
if (!priv)
return -ENOMEM;

- priv->ec_dev = ec_dev;
- priv->cmd_offset = ec->cmd_offset;
+ priv->pdata = pdata;
+ kref_get(&pdata->kref);
filp->private_data = priv;
INIT_LIST_HEAD(&priv->events);
init_waitqueue_head(&priv->wait_event);
nonseekable_open(inode, filp);

priv->notifier.notifier_call = cros_ec_chardev_mkbp_event;
- ret = blocking_notifier_chain_register(&ec_dev->event_notifier,
+ ret = blocking_notifier_chain_register(&pdata->ec_dev->event_notifier,
&priv->notifier);
if (ret) {
- dev_err(ec_dev->dev, "failed to register event notifier\n");
+ dev_err(pdata->ec_dev->dev,
+ "failed to register event notifier\n");
+ kref_put(&priv->pdata->kref, chardev_pdata_release);
kfree(priv);
}

@@ -267,11 +269,11 @@ static ssize_t cros_ec_chardev_read(struct file *filp, char __user *buffer,
static int cros_ec_chardev_release(struct inode *inode, struct file *filp)
{
struct chardev_priv *priv = filp->private_data;
- struct cros_ec_device *ec_dev = priv->ec_dev;
struct ec_event *event, *e;

- blocking_notifier_chain_unregister(&ec_dev->event_notifier,
+ blocking_notifier_chain_unregister(&priv->pdata->ec_dev->event_notifier,
&priv->notifier);
+ kref_put(&priv->pdata->kref, chardev_pdata_release);

list_for_each_entry_safe(event, e, &priv->events, node) {
list_del(&event->node);
@@ -314,8 +316,8 @@ static long cros_ec_chardev_ioctl_xcmd(struct chardev_priv *priv, void __user *a
goto exit;
}

- s_cmd->command += priv->cmd_offset;
- ret = cros_ec_cmd_xfer(priv->ec_dev, s_cmd);
+ s_cmd->command += priv->pdata->cmd_offset;
+ ret = cros_ec_cmd_xfer(priv->pdata->ec_dev, s_cmd);
/* Only copy data to userland if data was received. */
if (ret < 0)
goto exit;
@@ -329,7 +331,7 @@ static long cros_ec_chardev_ioctl_xcmd(struct chardev_priv *priv, void __user *a

static long cros_ec_chardev_ioctl_readmem(struct chardev_priv *priv, void __user *arg)
{
- struct cros_ec_device *ec_dev = priv->ec_dev;
+ struct cros_ec_device *ec_dev = priv->pdata->ec_dev;
struct cros_ec_readmem s_mem = { };
long num;

@@ -399,6 +401,8 @@ static int cros_ec_chardev_probe(struct platform_device *pdev)

platform_set_drvdata(pdev, pdata);
kref_init(&pdata->kref);
+ pdata->ec_dev = ec->ec_dev;
+ pdata->cmd_offset = ec->cmd_offset;

pdata->misc.minor = MISC_DYNAMIC_MINOR;
pdata->misc.fops = &chardev_fops;
--
2.51.0