[KINETIS] Slightly rewrite and comment i2c driver.

1 files changed, 143 insertions, 56 deletions

diff --git a/os/hal/ports/KINETIS/LLD/hal_i2c_lld.c b/os/hal/ports/KINETIS/LLD/hal_i2c_lld.c
index 1095737..0831eac 100644
--- a/os/hal/ports/KINETIS/LLD/hal_i2c_lld.c
+++ b/os/hal/ports/KINETIS/LLD/hal_i2c_lld.c
@@ -63,7 +63,7 @@ void config_frequency(I2CDriver *i2cp) {
    * divider used to generate the SCL clock from the main

    * system clock.

    */

-  uint16_t icr_table[] = {

+  const uint16_t icr_table[] = {

     /* 0x00 - 0x0F */

     20,22,24,26,28,30,34,40,28,32,36,40,44,48,56,68,

     /* 0x10 - 0x1F */

@@ -117,53 +117,116 @@ static void serve_interrupt(I2CDriver *i2cp) {
   I2C_TypeDef *i2c = i2cp->i2c;

   intstate_t state = i2cp->intstate;

 

-  if (i2c->S & I2Cx_S_ARBL) {

-

-    i2cp->errors |= I2C_ARBITRATION_LOST;

-    i2c->S |= I2Cx_S_ARBL;

-

-  } else if (state == STATE_SEND) {

-

-    if (i2c->S & I2Cx_S_RXAK)

-      i2cp->errors |= I2C_ACK_FAILURE;

-    else if (i2cp->txbuf != NULL && i2cp->txidx < i2cp->txbytes)

-      i2c->D = i2cp->txbuf[i2cp->txidx++];

-    else

-      i2cp->intstate = STATE_STOP;

-

-  } else if (state == STATE_DUMMY) {

-

-    if (i2c->S & I2Cx_S_RXAK)

-      i2cp->errors |= I2C_ACK_FAILURE;

-    else {

-      i2c->C1 &= ~I2Cx_C1_TX;

-

-      if (i2cp->rxbytes > 1)

-        i2c->C1 &= ~I2Cx_C1_TXAK;

-      else

-        i2c->C1 |= I2Cx_C1_TXAK;

-      (void) i2c->D;

-      i2cp->intstate = STATE_RECV;

-    }

-

-  } else if (state == STATE_RECV) {

-

-    if (i2cp->rxbytes > 1) {

-      if (i2cp->rxidx == (i2cp->rxbytes - 2))

-        i2c->C1 |= I2Cx_C1_TXAK;

-      else

-        i2c->C1 &= ~I2Cx_C1_TXAK;

-    }

+  /* check if we're master or slave */

+  if (i2c->C1 & I2Cx_C1_MST) {

+    /* master */

+

+    if (i2c->S & I2Cx_S_ARBL) {

+      /* check if we lost arbitration */

+      i2cp->errors |= I2C_ARBITRATION_LOST;

+      i2c->S |= I2Cx_S_ARBL;

+      /* TODO: may need to do more here, reset bus? */

+      /* Perhaps clear MST? */

+

+    } else if (i2c->S & I2Cx_S_TCF) {

+      /* just completed byte transfer */

+      if (i2c->C1 & I2Cx_C1_TX) {

+        /* the byte was transmitted */

+

+        if (state == STATE_SEND) {

+          /* currently sending stuff */

+

+          if (i2c->S & I2Cx_S_RXAK) {

+            /* slave did not ACK */

+            i2cp->errors |= I2C_ACK_FAILURE;

+            /* the thread will be woken up at the end of ISR and release the bus */

+

+          } else if (i2cp->txbuf != NULL && i2cp->txidx < i2cp->txbytes) {

+            /* slave ACK'd and we want to send more */

+            i2c->D = i2cp->txbuf[i2cp->txidx++];

+          } else {

+            /* slave ACK'd and we are done sending */

+            i2cp->intstate = STATE_STOP;

+            /* this wakes up the waiting thread at the end of ISR */

+          }

+

+        } else if (state == STATE_RECV) {

+          /* should be receiving stuff, so we've just sent the address */

+

+          if (i2c->S & I2Cx_S_RXAK) {

+            /* slave did not ACK */

+            i2cp->errors |= I2C_ACK_FAILURE;

+            /* the thread will be woken up and release the bus */

+

+          } else {

+            /* slave ACK'd, we should be receiving next */

+            i2c->C1 &= ~I2Cx_C1_TX;

+

+            if (i2cp->rxbytes > 1) {

+              /* multi-byte read, send ACK after next transfer */

+              i2c->C1 &= ~I2Cx_C1_TXAK;

+            } else {

+              /* only 1 byte remaining, send NAK */

+              i2c->C1 |= I2Cx_C1_TXAK;

+            }

+

+            (void) i2c->D; /* dummy read; triggers next receive */

+          }

+

+        } /* possibly check other states here - should not happen! */

+

+      } else {

+        /* the byte was received */

+

+        if (state == STATE_RECV) {

+          /* currently receiving stuff */

+          /* the received byte is now in D */

+

+          if (i2cp->rxbytes > 1) {

+            /* expecting at least one byte after this one */

+            if (i2cp->rxidx == (i2cp->rxbytes - 2)) {

+              /* expecting exactly one byte after this one, NAK that one */

+              i2c->C1 |= I2Cx_C1_TXAK;

+            } else {

+              /* expecting more than one after this one, respond with ACK */

+              i2c->C1 &= ~I2Cx_C1_TXAK;

+            }

+          }

+

+          if (i2cp->rxidx == i2cp->rxbytes - 1) {

+            /* D is the last byte we're expecting */

+            /* release bus: switch to RX mode, send STOP */

+            /* need to do it now otherwise the I2C module will wait for another byte */

+            // delayMicroseconds(1);

+            i2c->C1 &= ~(I2Cx_C1_TX | I2Cx_C1_MST);

+            i2cp->intstate = STATE_STOP;

+            /* this wakes up the waiting thread at the end of ISR */

+          }

+

+          /* get the data from D; this triggers the next receive */

+          i2cp->rxbuf[i2cp->rxidx++] = i2c->D;

+

+          // if (i2cp->rxidx == i2cp->rxbytes) {

+            /* done receiving */

+          // }

+        } /* possibly check other states here - should not happen! */

+      }

 

-    if (i2cp->rxidx == i2cp->rxbytes - 1)

-      i2c->C1 &= ~(I2Cx_C1_TX | I2Cx_C1_MST);

+    } /* possibly check other interrupt flags here */

 

-    i2cp->rxbuf[i2cp->rxidx++] = i2c->D;

+  } else {

+    /* slave */

 

-    if (i2cp->rxidx == i2cp->rxbytes)

-      i2cp->intstate = STATE_STOP;

+    /* Not implemented yet */

   }

 

+  /* Reset other interrupt sources */

+#if defined(I2Cx_FLT_STOPF) /* extra flags on KL26Z and KL27Z */

+  i2cp->i2c->FLT |= I2Cx_FLT_STOPF;

+#endif

+#if defined(I2Cx_FLT_STARTF) /* extra flags on KL27Z */

+  i2cp->i2c->FLT |= I2Cx_FLT_STARTF;

+#endif

   /* Reset interrupt flag */

   i2c->S |= I2Cx_S_IICIF;

 

@@ -260,8 +323,9 @@ void i2c_lld_start(I2CDriver *i2cp) {
   }

 

   config_frequency(i2cp);

-  i2cp->i2c->C1 |= I2Cx_C1_IICEN | I2Cx_C1_IICIE;

-  i2cp->intstate = STATE_STOP;

+  i2cp->i2c->C1 = I2Cx_C1_IICEN | I2Cx_C1_IICIE; // reset I2C, enable interrupts

+  i2cp->i2c->S = I2Cx_S_IICIF | I2Cx_S_ARBL; // clear status flags just in case

+  i2cp->intstate = STATE_STOP; // internal state

 }

 

 /**

@@ -315,35 +379,58 @@ static inline msg_t _i2c_txrx_timeout(I2CDriver *i2cp, i2caddr_t addr,
   i2cp->rxbytes = rxbytes;

   i2cp->rxidx = 0;

 

-  /* send START */

-  i2cp->i2c->C1 |= I2Cx_C1_MST;

-  i2cp->i2c->C1 |= I2Cx_C1_TX;

-

-  /* FIXME: should not use busy waiting! */

-  while (!(i2cp->i2c->S & I2Cx_S_BUSY));

+  /* clear status flags */

+#if defined(I2Cx_FLT_STOPF) /* extra flags on KL26Z and KL27Z */

+  i2cp->i2c->FLT |= I2Cx_FLT_STOPF;

+#endif

+#if defined(I2Cx_FLT_STARTF) /* extra flags on KL27Z */

+  i2cp->i2c->FLT |= I2Cx_FLT_STARTF;

+#endif

+  i2cp->i2c->S = I2Cx_S_IICIF|I2Cx_S_ARBL;

+

+  /* acquire the bus */

+  /* check to see if we already have the bus */

+  if(i2cp->i2c->C1 & I2Cx_C1_MST) {

+    /* send repeated start */

+    i2cp->i2c->C1 |= I2Cx_C1_RSTA | I2Cx_C1_TX;

+  } else {

+    /* wait until the bus is released */

+    /* TODO: implement timeout here */

+    /* FIXME: should not use busy waiting! */

+    while (i2cp->i2c->S & I2Cx_S_BUSY);

+    /* send START */

+    i2cp->i2c->C1 |= I2Cx_C1_MST|I2Cx_C1_TX;

+  }

 

+  /* send slave address */

   i2cp->i2c->D = addr << 1 | op;

 

+  /* wait for the ISR to signal that the transmission (or receive if no transmission) phase is complete */

   msg = osalThreadSuspendTimeoutS(&i2cp->thread, TIME_INFINITE);

 

   /* FIXME */

   //if (i2cp->i2c->S & I2Cx_S_RXAK)

   //  i2cp->errors |= I2C_ACK_FAILURE;

 

-  if (msg == MSG_OK && txbuf != NULL && rxbuf != NULL && rxbytes > 0) {

+  /* the transmitting (or receiving if no transmission) phase has finished,

+   * do we expect to receive something? */

+  if (msg == MSG_OK && rxbuf != NULL && rxbytes > 0 && i2cp->rxidx < rxbytes) {

+    /* send repeated start */

     i2cp->i2c->C1 |= I2Cx_C1_RSTA;

     /* FIXME */

-    while (!(i2cp->i2c->S & I2Cx_S_BUSY));

+    // while (!(i2cp->i2c->S & I2Cx_S_BUSY));

 

-    i2cp->intstate = STATE_DUMMY;

+    i2cp->intstate = STATE_RECV;

     i2cp->i2c->D = i2cp->addr << 1 | 1;

 

     msg = osalThreadSuspendTimeoutS(&i2cp->thread, TIME_INFINITE);

   }

 

+  /* release bus - RX mode, send STOP */

+  // other kinetis I2C drivers wait here for 1us. is this needed?

   i2cp->i2c->C1 &= ~(I2Cx_C1_TX | I2Cx_C1_MST);

   /* FIXME */

-  while (i2cp->i2c->S & I2Cx_S_BUSY);

+  // while (i2cp->i2c->S & I2Cx_S_BUSY);

 

   return msg;

 }

@@ -373,7 +460,7 @@ msg_t i2c_lld_master_receive_timeout(I2CDriver *i2cp, i2caddr_t addr,
                                      uint8_t *rxbuf, size_t rxbytes,

                                      systime_t timeout) {

 

-  i2cp->intstate = STATE_DUMMY;

+  i2cp->intstate = STATE_RECV;

   return _i2c_txrx_timeout(i2cp, addr, NULL, 0, rxbuf, rxbytes, timeout);

 }