Fix I2C NACK error

Fix logic error on replying NACK at the end of transfer.

This is also to fix FPGA CI test mbed_hal_fpga_ci_test_shield-i2c/
i2c - test single byte read i2c API.

Author: ccli8

targets/TARGET_NUVOTON/TARGET_M251/i2c_api.c

@@ -81,9 +81,10 @@ static void i2c_enable_vector_interrupt(i2c_t *obj, uint32_t handler, int enable
 static void i2c_rollback_vector_interrupt(i2c_t *obj);
 #endif
 
-#define TRANCTRL_STARTED        (1)
-#define TRANCTRL_NAKLASTDATA    (1 << 1)
-#define TRANCTRL_LASTDATANAKED  (1 << 2)
+#define TRANCTRL_STARTED        (1)         // Guard I2C ISR from data transfer prematurely
+#define TRANCTRL_NAKLASTDATA    (1 << 1)    // Request NACK on last data
+#define TRANCTRL_LASTDATANAKED  (1 << 2)    // Last data NACKed
+#define TRANCTRL_RECVDATA       (1 << 3)    // Receive data available
 
 uint32_t us_ticker_read(void);
 
@@ -583,11 +584,17 @@ static void i2c_irq(i2c_t *obj)
         if ((obj->i2c.tran_ctrl & TRANCTRL_STARTED) && obj->i2c.tran_pos) {
             if (obj->i2c.tran_pos < obj->i2c.tran_end) {
                 if (status == 0x50 || status == 0x58) {
-                    *obj->i2c.tran_pos ++ = I2C_GET_DATA(i2c_base);
+                    if (obj->i2c.tran_ctrl & TRANCTRL_RECVDATA) {
+                        *obj->i2c.tran_pos ++ = I2C_GET_DATA(i2c_base);
+                        obj->i2c.tran_ctrl &= ~TRANCTRL_RECVDATA;
+                    }
                 }
 
                 if (status == 0x58) {
                     i2c_fsm_tranfini(obj, 1);
+                } else if (obj->i2c.tran_pos == obj->i2c.tran_end) {
+                    obj->i2c.tran_ctrl &= ~TRANCTRL_STARTED;
+                    i2c_disable_int(obj);
                 } else {
                     uint32_t i2c_ctl = I2C_CTL0_SI_Msk | I2C_CTL0_AA_Msk;
                     if ((obj->i2c.tran_end - obj->i2c.tran_pos) == 1 &&
@@ -596,6 +603,7 @@ static void i2c_irq(i2c_t *obj)
                         i2c_ctl &= ~I2C_CTL0_AA_Msk;
                     }
                     I2C_SET_CONTROL_REG(i2c_base, i2c_ctl);
+                    obj->i2c.tran_ctrl |= TRANCTRL_RECVDATA;
                 }
             } else {
                 obj->i2c.tran_ctrl &= ~TRANCTRL_STARTED;
@@ -650,12 +658,18 @@ static void i2c_irq(i2c_t *obj)
         if ((obj->i2c.tran_ctrl & TRANCTRL_STARTED) && obj->i2c.tran_pos) {
             if (obj->i2c.tran_pos < obj->i2c.tran_end) {
                 if (status == 0x80 || status == 0x88) {
-                    *obj->i2c.tran_pos ++ = I2C_GET_DATA(i2c_base);
+                    if (obj->i2c.tran_ctrl & TRANCTRL_RECVDATA) {
+                        *obj->i2c.tran_pos ++ = I2C_GET_DATA(i2c_base);
+                        obj->i2c.tran_ctrl &= ~TRANCTRL_RECVDATA;
+                    }
                 }
 
                 if (status == 0x88) {
                     obj->i2c.slaveaddr_state = NoData;
                     i2c_fsm_reset(obj, I2C_CTL0_SI_Msk | I2C_CTL0_AA_Msk);
+                } else if (obj->i2c.tran_pos == obj->i2c.tran_end) {
+                    obj->i2c.tran_ctrl &= ~TRANCTRL_STARTED;
+                    i2c_disable_int(obj);
                 } else {
                     uint32_t i2c_ctl = I2C_CTL0_SI_Msk | I2C_CTL0_AA_Msk;
                     if ((obj->i2c.tran_end - obj->i2c.tran_pos) == 1 &&
@@ -664,6 +678,7 @@ static void i2c_irq(i2c_t *obj)
                         i2c_ctl &= ~I2C_CTL0_AA_Msk;
                     }
                     I2C_SET_CONTROL_REG(i2c_base, i2c_ctl);
+                    obj->i2c.tran_ctrl |= TRANCTRL_RECVDATA;
                 }
             } else {
                 obj->i2c.tran_ctrl &= ~TRANCTRL_STARTED;
@@ -686,12 +701,18 @@ static void i2c_irq(i2c_t *obj)
         if ((obj->i2c.tran_ctrl & TRANCTRL_STARTED) && obj->i2c.tran_pos) {
             if (obj->i2c.tran_pos < obj->i2c.tran_end) {
                 if (status == 0x90 || status == 0x98) {
-                    *obj->i2c.tran_pos ++ = I2C_GET_DATA(i2c_base);
+                    if (obj->i2c.tran_ctrl & TRANCTRL_RECVDATA) {
+                        *obj->i2c.tran_pos ++ = I2C_GET_DATA(i2c_base);
+                        obj->i2c.tran_ctrl &= ~TRANCTRL_RECVDATA;
+                    }
                 }
 
                 if (status == 0x98) {
                     obj->i2c.slaveaddr_state = NoData;
                     i2c_fsm_reset(obj, I2C_CTL0_SI_Msk | I2C_CTL0_AA_Msk);
+                } else if (obj->i2c.tran_pos == obj->i2c.tran_end) {
+                    obj->i2c.tran_ctrl &= ~TRANCTRL_STARTED;
+                    i2c_disable_int(obj);
                 } else {
                     uint32_t i2c_ctl = I2C_CTL0_SI_Msk | I2C_CTL0_AA_Msk;
                     if ((obj->i2c.tran_end - obj->i2c.tran_pos) == 1 &&
@@ -700,6 +721,7 @@ static void i2c_irq(i2c_t *obj)
                         i2c_ctl &= ~I2C_CTL0_AA_Msk;
                     }
                     I2C_SET_CONTROL_REG(i2c_base, i2c_ctl);
+                    obj->i2c.tran_ctrl |= TRANCTRL_RECVDATA;
                 }
             } else {
                 obj->i2c.tran_ctrl &= ~TRANCTRL_STARTED;