From 3e1fd9f4947b8bce1c896b3920b7abf528fd31b8 Mon Sep 17 00:00:00 2001
From: MrKevinWeiss <weiss.kevin604@gmail.com>
Date: Thu, 25 Oct 2018 11:24:57 +0200
Subject: [PATCH] cpu/stm32_common/i2c: Fix error handling in i2c_1.c

Errors flags could not clear making the i2c unusable after error.
This fix removes the error check in start so the error flags can clear and does proper checking for status bits before _bus_check.
---
 cpu/stm32_common/periph/i2c_1.c | 36 ++++++++++++---------------------
 1 file changed, 13 insertions(+), 23 deletions(-)

diff --git a/cpu/stm32_common/periph/i2c_1.c b/cpu/stm32_common/periph/i2c_1.c
index 5caf9aabd5..ffac79370a 100644
--- a/cpu/stm32_common/periph/i2c_1.c
+++ b/cpu/stm32_common/periph/i2c_1.c
@@ -216,7 +216,7 @@ int i2c_read_regs(i2c_t dev, uint16_t address, uint16_t reg, void *data,
 
     /* Check to see if the bus is busy */
     while ((i2c->ISR & I2C_ISR_BUSY) && tick--) {}
-    if ((i2c->ISR & ERROR_FLAG) || !tick) {
+    if (!tick) {
         return -ETIMEDOUT;
     }
 
@@ -308,7 +308,7 @@ int i2c_write_regs(i2c_t dev, uint16_t address, uint16_t reg, const void *data,
 
     /* Check to see if the bus is busy */
     while ((i2c->ISR & I2C_ISR_BUSY) && tick--) {}
-    if ((i2c->ISR & ERROR_FLAG) || !tick) {
+    if (!tick) {
         return -ETIMEDOUT;
     }
 
@@ -387,17 +387,12 @@ static inline int _start(I2C_TypeDef *i2c, uint16_t address,
 
     /* Wait for the start followed by the address to be sent */
     uint16_t tick = TICK_TIMEOUT;
-    while (!(i2c->CR2 & I2C_CR2_START) && tick--) {}
+    while ((i2c->CR2 & I2C_CR2_START) && tick--) {}
     if (!tick) {
         return -ETIMEDOUT;
     }
 
-    int ret = _check_bus(i2c);
-    if (ret < 0) {
-        return ret;
-    }
-
-    return 0;
+    return _check_bus(i2c);
 }
 
 static inline int _read(I2C_TypeDef *i2c, uint8_t *data, size_t length)
@@ -420,12 +415,7 @@ static inline int _read(I2C_TypeDef *i2c, uint8_t *data, size_t length)
         DEBUG("[i2c] read: Read byte %i from DR\n", i);
     }
 
-    int ret = _check_bus(i2c);
-    if (ret < 0) {
-        return ret;
-    }
-
-    return 0;
+    return _check_bus(i2c);
 }
 
 static inline int _write(I2C_TypeDef *i2c, const uint8_t *data, size_t length)
@@ -446,6 +436,12 @@ static inline int _write(I2C_TypeDef *i2c, const uint8_t *data, size_t length)
         i2c->TXDR = data[i];
         DEBUG("[i2c] write: Sending data\n");
 
+        tick = TICK_TIMEOUT;
+        while (!(i2c->ISR & I2C_ISR_TC) && tick--) {}
+        if (!tick) {
+            return -ETIMEDOUT;
+        }
+
         int ret = _check_bus(i2c);
         if (ret < 0) {
             return ret;
@@ -482,7 +478,7 @@ static inline int _stop(I2C_TypeDef *i2c)
 
     /* Wait for the stop to complete */
     tick = TICK_TIMEOUT;
-    while (!(i2c->CR2 & I2C_CR2_STOP) && tick--) {}
+    while ((i2c->CR2 & I2C_CR2_STOP) && tick--) {}
     if (!tick) {
         return -ETIMEDOUT;
     }
@@ -494,12 +490,6 @@ static inline int _check_bus(I2C_TypeDef *i2c)
 {
     assert(i2c != NULL);
 
-    int ret = 0;
-
-    /* wait a bit for any potential error to arrive */
-    uint16_t tick = TICK_TIMEOUT;
-    while (tick--) {}
-
     if (i2c->ISR & I2C_ISR_NACKF) {
         DEBUG("[i2c] check_bus: NACK received\n");
         return -ENXIO;
@@ -515,7 +505,7 @@ static inline int _check_bus(I2C_TypeDef *i2c)
         return -EIO;
     }
 
-    return ret;
+    return 0;
 }
 
 static inline void irq_handler(i2c_t dev)