linux-kernel - [PATCH v8 09/22] counter: Return error code on invalid modes

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Message-Id: <58e7c59bb7c7bb94c8655903308842d9d9e9907a.1613131238.git.vilhelm.gray@gmail.com>
Date:   Fri, 12 Feb 2021 21:13:33 +0900
From:   William Breathitt Gray <vilhelm.gray@...il.com>
To:     jic23@...nel.org
Cc:     kernel@...gutronix.de, linux-stm32@...md-mailman.stormreply.com,
        a.fatoum@...gutronix.de, kamel.bouhara@...tlin.com,
        gwendal@...omium.org, alexandre.belloni@...tlin.com,
        david@...hnology.com, linux-iio@...r.kernel.org,
        linux-kernel@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
        syednwaris@...il.com, patrick.havelange@...ensium.com,
        fabrice.gasnier@...com, mcoquelin.stm32@...il.com,
        alexandre.torgue@...com, o.rempel@...gutronix.de,
        William Breathitt Gray <vilhelm.gray@...il.com>
Subject: [PATCH v8 09/22] counter: Return error code on invalid modes

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 <syednwaris@...il.com>
Cc: Kamel Bouhara <kamel.bouhara@...tlin.com>
Cc: Fabrice Gasnier <fabrice.gasnier@...com>
Cc: Maxime Coquelin <mcoquelin.stm32@...il.com>
Cc: Alexandre Torgue <alexandre.torgue@...com>
Cc: David Lechner <david@...hnology.com>
Signed-off-by: William Breathitt Gray <vilhelm.gray@...il.com>
---
 drivers/counter/104-quad-8.c            | 10 ++++++++++
 drivers/counter/microchip-tcb-capture.c |  6 ++++++
 drivers/counter/stm32-lptimer-cnt.c     | 10 ++++++----
 drivers/counter/stm32-timer-cnt.c       |  3 +++
 drivers/counter/ti-eqep.c               |  3 +++
 5 files changed, 28 insertions(+), 4 deletions(-)

diff --git a/drivers/counter/104-quad-8.c b/drivers/counter/104-quad-8.c
index 9a96296b0625..674263b4d2c4 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;
 		}
 	}
 
@@ -367,6 +371,9 @@ static int quad8_action_get(struct counter_device *counter,
 	case QUAD8_COUNT_FUNCTION_QUADRATURE_X4:
 		*action = QUAD8_SYNAPSE_ACTION_BOTH_EDGES;
 		break;
+	default:
+		/* should never reach this path */
+		return -EINVAL;
 	}
 
 	return 0;
@@ -529,6 +536,9 @@ 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 710acc0a3704..ee979b011012 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 937439635d53..daf988e7b208 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/stm32-timer-cnt.c b/drivers/counter/stm32-timer-cnt.c
index ef2a974a2f10..431a3d08ed6c 100644
--- a/drivers/counter/stm32-timer-cnt.c
+++ b/drivers/counter/stm32-timer-cnt.c
@@ -296,6 +296,9 @@ static int stm32_action_get(struct counter_device *counter,
 		/* counts up/down on both TI1FP1 and TI2FP2 edges */
 		*action = STM32_SYNAPSE_ACTION_BOTH_EDGES;
 		break;
+	default:
+		/* should never reach this path */
+		return -EINVAL;
 	}
 
 	return 0;
diff --git a/drivers/counter/ti-eqep.c b/drivers/counter/ti-eqep.c
index a60aee1a1a29..7844fdf78a97 100644
--- a/drivers/counter/ti-eqep.c
+++ b/drivers/counter/ti-eqep.c
@@ -192,6 +192,9 @@ static int ti_eqep_action_get(struct counter_device *counter,
 			break;
 		}
 		break;
+	default:
+		/* should never reach this path */
+		return -EINVAL;
 	}
 
 	return 0;
-- 
2.30.0