On Fri, Mar 19, 2021 at 08:00:37PM +0900, William Breathitt Gray wrote:
> Only a select set of modes (function, action, etc.) are valid for a
> given device configuration. This patch ensures that invalid modes result
> in a return -EINVAL. Such a situation should never occur in reality, but
> it's good to define a default switch cases for the sake of making the
> intent of the code clear.
> 
> Cc: Syed Nayyar Waris <syednwa...@gmail.com>
> Cc: Kamel Bouhara <kamel.bouh...@bootlin.com>
> Cc: Fabrice Gasnier <fabrice.gasn...@st.com>
> Cc: Maxime Coquelin <mcoquelin.st...@gmail.com>
> Cc: Alexandre Torgue <alexandre.tor...@st.com>
> Cc: David Lechner <da...@lechnology.com>
> Signed-off-by: William Breathitt Gray <vilhelm.g...@gmail.com>
> ---
>  drivers/counter/104-quad-8.c            | 20 +++++++----

For the 104-quad-8 driver:
Acked-by: Syed Nayyar Waris <syednwa...@gmail.com>

>  drivers/counter/microchip-tcb-capture.c |  6 ++++
>  drivers/counter/stm32-lptimer-cnt.c     | 10 +++---
>  drivers/counter/ti-eqep.c               | 45 +++++++++++--------------
>  4 files changed, 46 insertions(+), 35 deletions(-)
> 
> diff --git a/drivers/counter/104-quad-8.c b/drivers/counter/104-quad-8.c
> index 09d779544969..b7d6c1c43655 100644
> --- a/drivers/counter/104-quad-8.c
> +++ b/drivers/counter/104-quad-8.c
> @@ -273,6 +273,10 @@ static int quad8_function_set(struct counter_device 
> *counter,
>                       *scale = 2;
>                       mode_cfg |= QUAD8_CMR_QUADRATURE_X4;
>                       break;
> +             default:
> +                     /* should never reach this path */
> +                     mutex_unlock(&priv->lock);
> +                     return -EINVAL;
>               }
>       }
>  
> @@ -349,7 +353,7 @@ static int quad8_action_get(struct counter_device 
> *counter,
>       case QUAD8_COUNT_FUNCTION_PULSE_DIRECTION:
>               if (synapse->signal->id == signal_a_id)
>                       *action = QUAD8_SYNAPSE_ACTION_RISING_EDGE;
> -             break;
> +             return 0;
>       case QUAD8_COUNT_FUNCTION_QUADRATURE_X1:
>               if (synapse->signal->id == signal_a_id) {
>                       quad8_direction_get(counter, count, &direction);
> @@ -359,17 +363,18 @@ static int quad8_action_get(struct counter_device 
> *counter,
>                       else
>                               *action = QUAD8_SYNAPSE_ACTION_FALLING_EDGE;
>               }
> -             break;
> +             return 0;
>       case QUAD8_COUNT_FUNCTION_QUADRATURE_X2:
>               if (synapse->signal->id == signal_a_id)
>                       *action = QUAD8_SYNAPSE_ACTION_BOTH_EDGES;
> -             break;
> +             return 0;
>       case QUAD8_COUNT_FUNCTION_QUADRATURE_X4:
>               *action = QUAD8_SYNAPSE_ACTION_BOTH_EDGES;
> -             break;
> +             return 0;
> +     default:
> +             /* should never reach this path */
> +             return -EINVAL;
>       }
> -
> -     return 0;
>  }
>  
>  static const struct counter_ops quad8_ops = {
> @@ -529,6 +534,9 @@ static int quad8_count_mode_set(struct counter_device 
> *counter,
>       case COUNTER_COUNT_MODE_MODULO_N:
>               cnt_mode = 3;
>               break;
> +     default:
> +             /* should never reach this path */
> +             return -EINVAL;
>       }
>  
>       mutex_lock(&priv->lock);
> diff --git a/drivers/counter/microchip-tcb-capture.c 
> b/drivers/counter/microchip-tcb-capture.c
> index 51b8af80f98b..0c9a61962911 100644
> --- a/drivers/counter/microchip-tcb-capture.c
> +++ b/drivers/counter/microchip-tcb-capture.c
> @@ -133,6 +133,9 @@ static int mchp_tc_count_function_set(struct 
> counter_device *counter,
>               bmr |= ATMEL_TC_QDEN | ATMEL_TC_POSEN;
>               cmr |= ATMEL_TC_ETRGEDG_RISING | ATMEL_TC_ABETRG | ATMEL_TC_XC0;
>               break;
> +     default:
> +             /* should never reach this path */
> +             return -EINVAL;
>       }
>  
>       regmap_write(priv->regmap, ATMEL_TC_BMR, bmr);
> @@ -226,6 +229,9 @@ static int mchp_tc_count_action_set(struct counter_device 
> *counter,
>       case MCHP_TC_SYNAPSE_ACTION_BOTH_EDGE:
>               edge = ATMEL_TC_ETRGEDG_BOTH;
>               break;
> +     default:
> +             /* should never reach this path */
> +             return -EINVAL;
>       }
>  
>       return regmap_write_bits(priv->regmap,
> diff --git a/drivers/counter/stm32-lptimer-cnt.c 
> b/drivers/counter/stm32-lptimer-cnt.c
> index c19d998df5ba..78f383b77bd2 100644
> --- a/drivers/counter/stm32-lptimer-cnt.c
> +++ b/drivers/counter/stm32-lptimer-cnt.c
> @@ -206,9 +206,10 @@ static int stm32_lptim_cnt_function_set(struct 
> counter_device *counter,
>               priv->quadrature_mode = 1;
>               priv->polarity = STM32_LPTIM_SYNAPSE_ACTION_BOTH_EDGES;
>               return 0;
> +     default:
> +             /* should never reach this path */
> +             return -EINVAL;
>       }
> -
> -     return -EINVAL;
>  }
>  
>  static ssize_t stm32_lptim_cnt_enable_read(struct counter_device *counter,
> @@ -326,9 +327,10 @@ static int stm32_lptim_cnt_action_get(struct 
> counter_device *counter,
>       case STM32_LPTIM_ENCODER_BOTH_EDGE:
>               *action = priv->polarity;
>               return 0;
> +     default:
> +             /* should never reach this path */
> +             return -EINVAL;
>       }
> -
> -     return -EINVAL;
>  }
>  
>  static int stm32_lptim_cnt_action_set(struct counter_device *counter,
> diff --git a/drivers/counter/ti-eqep.c b/drivers/counter/ti-eqep.c
> index 65df9ef5b5bc..878725c2f010 100644
> --- a/drivers/counter/ti-eqep.c
> +++ b/drivers/counter/ti-eqep.c
> @@ -157,44 +157,39 @@ static int ti_eqep_action_get(struct counter_device 
> *counter,
>                * QEPA and QEPB trigger QCLK.
>                */
>               *action = TI_EQEP_SYNAPSE_ACTION_BOTH_EDGES;
> -             break;
> +             return 0;
>       case TI_EQEP_COUNT_FUNC_DIR_COUNT:
>               /* In direction-count mode only rising edge of QEPA is counted
>                * and QEPB gives direction.
>                */
> -             switch (synapse->signal->id) {
> -             case TI_EQEP_SIGNAL_QEPA:
> -                     *action = TI_EQEP_SYNAPSE_ACTION_RISING_EDGE;
> -                     break;
> -             default:
> +             if (synapse->signal->id == TI_EQEP_SIGNAL_QEPB)
>                       *action = TI_EQEP_SYNAPSE_ACTION_NONE;
> -                     break;
> -             }
> -             break;
> +             else
> +                     *action = TI_EQEP_SYNAPSE_ACTION_RISING_EDGE;
> +             return 0;
>       case TI_EQEP_COUNT_FUNC_UP_COUNT:
>       case TI_EQEP_COUNT_FUNC_DOWN_COUNT:
>               /* In up/down-count modes only QEPA is counted and QEPB is not
>                * used.
>                */
> -             switch (synapse->signal->id) {
> -             case TI_EQEP_SIGNAL_QEPA:
> -                     err = regmap_read(priv->regmap16, QDECCTL, &qdecctl);
> -                     if (err)
> -                             return err;
> -
> -                     if (qdecctl & QDECCTL_XCR)
> -                             *action = TI_EQEP_SYNAPSE_ACTION_BOTH_EDGES;
> -                     else
> -                             *action = TI_EQEP_SYNAPSE_ACTION_RISING_EDGE;
> -                     break;
> -             default:
> +             if (synapse->signal->id == TI_EQEP_SIGNAL_QEPB) {
>                       *action = TI_EQEP_SYNAPSE_ACTION_NONE;
> -                     break;
> +                     return 0;
>               }
> -             break;
> -     }
>  
> -     return 0;
> +             err = regmap_read(priv->regmap16, QDECCTL, &qdecctl);
> +             if (err)
> +                     return err;
> +
> +             if (qdecctl & QDECCTL_XCR)
> +                     *action = TI_EQEP_SYNAPSE_ACTION_BOTH_EDGES;
> +             else
> +                     *action = TI_EQEP_SYNAPSE_ACTION_RISING_EDGE;
> +             return 0;
> +     default:
> +             /* should never reach this path */
> +             return -EINVAL;
> +     }
>  }
>  
>  static const struct counter_ops ti_eqep_counter_ops = {
> -- 
> 2.30.2
> 

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