Input: iqs626a - drop unused device node references

Each call to device/fwnode_get_named_child_node() must be matched
with a call to fwnode_handle_put() once the corresponding node is
no longer in use. This ensures a reference count remains balanced
in the case of dynamic device tree support.

Currently, the driver never calls fwnode_handle_put(); this patch
adds the missing calls. Because fwnode_handle_put() does not take
a const *fwnode_handle, the const qualifier is removed across all
corresponding *fwnode_handle instances.

To facilitate this change, the logic that parses event thresholds
is collapsed in order to limit the number of locations from which
fwnode_handle_put() must be called.

Fixes: f1d2809de97a ("Input: Add support for Azoteq IQS626A")
Signed-off-by: Jeff LaBundy <jeff@labundy.com>
---
 drivers/input/misc/iqs626a.c | 87 +++++++++++++++++-------------------
 1 file changed, 42 insertions(+), 45 deletions(-)

On Tue, Jan 03, 2023 at 11:33, Jeff LaBundy <jeff@labundy.com> wrote:

> Each call to device/fwnode_get_named_child_node() must be matched
> with a call to fwnode_handle_put() once the corresponding node is
> no longer in use. This ensures a reference count remains balanced
> in the case of dynamic device tree support.
>
> Currently, the driver never calls fwnode_handle_put(); this patch
> adds the missing calls. Because fwnode_handle_put() does not take
> a const *fwnode_handle, the const qualifier is removed across all
> corresponding *fwnode_handle instances.
>
> To facilitate this change, the logic that parses event thresholds
> is collapsed in order to limit the number of locations from which
> fwnode_handle_put() must be called.
>
> Fixes: f1d2809de97a ("Input: Add support for Azoteq IQS626A")
> Signed-off-by: Jeff LaBundy <jeff@labundy.com>

Reviewed-by: Mattijs Korpershoek <mkorpershoek@baylibre.com>

> ---
>  drivers/input/misc/iqs626a.c | 87 +++++++++++++++++-------------------
>  1 file changed, 42 insertions(+), 45 deletions(-)
>
> diff --git a/drivers/input/misc/iqs626a.c b/drivers/input/misc/iqs626a.c
> index 23b5dd9552dc..060efb75f8cf 100644
> --- a/drivers/input/misc/iqs626a.c
> +++ b/drivers/input/misc/iqs626a.c
> @@ -458,12 +458,11 @@ struct iqs626_private {
>  
>  static noinline_for_stack int
>  iqs626_parse_events(struct iqs626_private *iqs626,
> -		    const struct fwnode_handle *ch_node,
> -		    enum iqs626_ch_id ch_id)
> +		    struct fwnode_handle *ch_node, enum iqs626_ch_id ch_id)
>  {
>  	struct iqs626_sys_reg *sys_reg = &iqs626->sys_reg;
>  	struct i2c_client *client = iqs626->client;
> -	const struct fwnode_handle *ev_node;
> +	struct fwnode_handle *ev_node;
>  	const char *ev_name;
>  	u8 *thresh, *hyst;
>  	unsigned int thresh_tp[IQS626_NUM_CH_TP_3];
> @@ -509,7 +508,7 @@ iqs626_parse_events(struct iqs626_private *iqs626,
>  			 * Trackpad touch events are simply described under the
>  			 * trackpad child node.
>  			 */
> -			ev_node = ch_node;
> +			ev_node = fwnode_handle_get(ch_node);
>  		} else {
>  			ev_name = iqs626_events[i].name;
>  			ev_node = fwnode_get_named_child_node(ch_node, ev_name);
> @@ -533,6 +532,7 @@ iqs626_parse_events(struct iqs626_private *iqs626,
>  					dev_err(&client->dev,
>  						"Invalid input type: %u\n",
>  						val);
> +					fwnode_handle_put(ev_node);
>  					return -EINVAL;
>  				}
>  
> @@ -547,6 +547,7 @@ iqs626_parse_events(struct iqs626_private *iqs626,
>  				dev_err(&client->dev,
>  					"Invalid %s channel hysteresis: %u\n",
>  					fwnode_get_name(ch_node), val);
> +				fwnode_handle_put(ev_node);
>  				return -EINVAL;
>  			}
>  
> @@ -561,29 +562,12 @@ iqs626_parse_events(struct iqs626_private *iqs626,
>  			}
>  		}
>  
> -		if (ch_id != IQS626_CH_TP_2 && ch_id != IQS626_CH_TP_3 &&
> -		    !fwnode_property_read_u32(ev_node, "azoteq,thresh", &val)) {
> -			if (val > IQS626_CHx_THRESH_MAX) {
> -				dev_err(&client->dev,
> -					"Invalid %s channel threshold: %u\n",
> -					fwnode_get_name(ch_node), val);
> -				return -EINVAL;
> -			}
> -
> -			if (ch_id == IQS626_CH_HALL)
> -				*thresh = val;
> -			else
> -				*(thresh + iqs626_events[i].th_offs) = val;
> -
> -			continue;
> -		}
> -
> -		if (!fwnode_property_present(ev_node, "azoteq,thresh"))
> -			continue;
> -
>  		error = fwnode_property_read_u32_array(ev_node, "azoteq,thresh",
>  						       thresh_tp, num_ch);
> -		if (error) {
> +		fwnode_handle_put(ev_node);
> +		if (error == -EINVAL) {
> +			continue;
> +		} else if (error) {
>  			dev_err(&client->dev,
>  				"Failed to read %s channel thresholds: %d\n",
>  				fwnode_get_name(ch_node), error);
> @@ -598,6 +582,20 @@ iqs626_parse_events(struct iqs626_private *iqs626,
>  				return -EINVAL;
>  			}
>  
> +			switch (ch_id) {
> +			case IQS626_CH_TP_2:
> +			case IQS626_CH_TP_3:
> +				break;
> +
> +			case IQS626_CH_HALL:
> +				*thresh = thresh_tp[j];
> +				continue;
> +
> +			default:
> +				thresh[iqs626_events[i].th_offs] = thresh_tp[j];
> +				continue;
> +			}
> +
>  			sys_reg->tp_grp_reg.ch_reg_tp[j].thresh = thresh_tp[j];
>  		}
>  	}
> @@ -607,8 +605,7 @@ iqs626_parse_events(struct iqs626_private *iqs626,
>  
>  static noinline_for_stack int
>  iqs626_parse_ati_target(struct iqs626_private *iqs626,
> -			const struct fwnode_handle *ch_node,
> -			enum iqs626_ch_id ch_id)
> +			struct fwnode_handle *ch_node, enum iqs626_ch_id ch_id)
>  {
>  	struct iqs626_sys_reg *sys_reg = &iqs626->sys_reg;
>  	struct i2c_client *client = iqs626->client;
> @@ -716,7 +713,7 @@ iqs626_parse_ati_target(struct iqs626_private *iqs626,
>  }
>  
>  static int iqs626_parse_pins(struct iqs626_private *iqs626,
> -			     const struct fwnode_handle *ch_node,
> +			     struct fwnode_handle *ch_node,
>  			     const char *propname, u8 *enable)
>  {
>  	struct i2c_client *client = iqs626->client;
> @@ -764,7 +761,7 @@ static int iqs626_parse_pins(struct iqs626_private *iqs626,
>  }
>  
>  static int iqs626_parse_trackpad(struct iqs626_private *iqs626,
> -				 const struct fwnode_handle *ch_node)
> +				 struct fwnode_handle *ch_node)
>  {
>  	struct iqs626_sys_reg *sys_reg = &iqs626->sys_reg;
>  	struct i2c_client *client = iqs626->client;
> @@ -889,8 +886,7 @@ static int iqs626_parse_trackpad(struct iqs626_private *iqs626,
>  
>  static noinline_for_stack int
>  iqs626_parse_channel(struct iqs626_private *iqs626,
> -		     const struct fwnode_handle *ch_node,
> -		     enum iqs626_ch_id ch_id)
> +		     struct fwnode_handle *ch_node, enum iqs626_ch_id ch_id)
>  {
>  	struct iqs626_sys_reg *sys_reg = &iqs626->sys_reg;
>  	struct i2c_client *client = iqs626->client;
> @@ -924,6 +920,20 @@ iqs626_parse_channel(struct iqs626_private *iqs626,
>  		return -EINVAL;
>  	}
>  
> +	error = iqs626_parse_ati_target(iqs626, ch_node, ch_id);
> +	if (error)
> +		return error;
> +
> +	error = iqs626_parse_events(iqs626, ch_node, ch_id);
> +	if (error)
> +		return error;
> +
> +	if (!fwnode_property_present(ch_node, "azoteq,ati-exclude"))
> +		sys_reg->redo_ati |= iqs626_channels[ch_id].active;
> +
> +	if (!fwnode_property_present(ch_node, "azoteq,reseed-disable"))
> +		sys_reg->reseed |= iqs626_channels[ch_id].active;
> +
>  	*engine |= IQS626_CHx_ENG_0_MEAS_CAP_SIZE;
>  	if (fwnode_property_present(ch_node, "azoteq,meas-cap-decrease"))
>  		*engine &= ~IQS626_CHx_ENG_0_MEAS_CAP_SIZE;
> @@ -1378,23 +1388,10 @@ static int iqs626_parse_prop(struct iqs626_private *iqs626)
>  			continue;
>  
>  		error = iqs626_parse_channel(iqs626, ch_node, i);
> +		fwnode_handle_put(ch_node);
>  		if (error)
>  			return error;
>  
> -		error = iqs626_parse_ati_target(iqs626, ch_node, i);
> -		if (error)
> -			return error;
> -
> -		error = iqs626_parse_events(iqs626, ch_node, i);
> -		if (error)
> -			return error;
> -
> -		if (!fwnode_property_present(ch_node, "azoteq,ati-exclude"))
> -			sys_reg->redo_ati |= iqs626_channels[i].active;
> -
> -		if (!fwnode_property_present(ch_node, "azoteq,reseed-disable"))
> -			sys_reg->reseed |= iqs626_channels[i].active;
> -
>  		sys_reg->active |= iqs626_channels[i].active;
>  	}
>  
> -- 
> 2.34.1