bsp/imx: Add I2C bus driver

Update #3090.

3 files changed, 451 insertions, 0 deletions

diff --git a/c/src/lib/libbsp/arm/imx/Makefile.am b/c/src/lib/libbsp/arm/imx/Makefile.am
index e206614676..42352fb950 100644
--- a/c/src/lib/libbsp/arm/imx/Makefile.am
+++ b/c/src/lib/libbsp/arm/imx/Makefile.am
@@ -117,6 +117,9 @@ libbsp_a_SOURCES += ../shared/include/arm-cache-l1.h
 libbsp_a_SOURCES += ../shared/armv467ar-basic-cache/cache_.h
 libbsp_a_CPPFLAGS += -I$(srcdir)/../shared/armv467ar-basic-cache
 
+# I2C
+libbsp_a_SOURCES += i2c/imx-i2c.c
+
 # Start hooks
 libbsp_a_SOURCES += startup/bspstarthooks.c
 
diff --git a/c/src/lib/libbsp/arm/imx/i2c/imx-i2c.c b/c/src/lib/libbsp/arm/imx/i2c/imx-i2c.c
new file mode 100644
index 0000000000..eec1a2e497
--- /dev/null
+++ b/c/src/lib/libbsp/arm/imx/i2c/imx-i2c.c
@@ -0,0 +1,437 @@
+/*
+ * Copyright (c) 2017 embedded brains GmbH.  All rights reserved.
+ *
+ *  embedded brains GmbH
+ *  Dornierstr. 4
+ *  82178 Puchheim
+ *  Germany
+ *  <info@embedded-brains.de>
+ *
+ * The license and distribution terms for this file may be
+ * found in the file LICENSE in this distribution or at
+ * http://www.rtems.org/license/LICENSE.
+ */
+
+#include <bsp.h>
+#include <bsp/fdt.h>
+#include <libfdt.h>
+#include <arm/freescale/imx/imx_ccmvar.h>
+#include <arm/freescale/imx/imx_i2creg.h>
+#include <dev/i2c/i2c.h>
+#include <rtems/irq-extension.h>
+
+#define IMX_I2C_TRANSMIT (IMX_I2C_I2CR_IEN | IMX_I2C_I2CR_IIEN \
+  | IMX_I2C_I2CR_MSTA | IMX_I2C_I2CR_MTX)
+
+#define IMX_I2C_RECEIVE (IMX_I2C_I2CR_IEN | IMX_I2C_I2CR_IIEN \
+  | IMX_I2C_I2CR_MSTA)
+
+typedef struct {
+  i2c_bus base;
+  volatile imx_i2c *regs;
+  uint32_t msg_todo;
+  const i2c_msg *msg;
+  bool read;
+  bool start;
+  uint16_t restart;
+  uint32_t chunk_total;
+  uint32_t chunk_done;
+  uint16_t buf_todo;
+  uint8_t *buf;
+  rtems_id task_id;
+  int eno;
+  rtems_vector_number irq;
+} imx_i2c_bus;
+
+typedef struct {
+  uint16_t divisor;
+  uint8_t ifdr;
+} imx_i2c_clock_divisor;
+
+static const imx_i2c_clock_divisor imx_i2c_clock_divisor_table[] = {
+  {    0, 0x20 }, {   22, 0x20 }, {   24, 0x21 }, {     26, 0x22 },
+  {   28, 0x23 }, {   30, 0x00 }, {   32, 0x24 }, {     36, 0x25 },
+  {   40, 0x26 }, {   42, 0x03 }, {   44, 0x27 }, {     48, 0x28 },
+  {   52, 0x05 }, {   56, 0x29 }, {   60, 0x06 }, {     64, 0x2a },
+  {   72, 0x2b }, {   80, 0x2c }, {   88, 0x09 }, {     96, 0x2d },
+  {  104, 0x0a }, {  112, 0x2e }, {  128, 0x2f }, {    144, 0x0c },
+  {  160, 0x30 }, {  192, 0x31 }, {  224, 0x32 }, {    240, 0x0f },
+  {  256, 0x33 }, {  288, 0x10 }, {  320, 0x34 }, {    384, 0x35 },
+  {  448, 0x36 }, {  480, 0x13 }, {  512, 0x37 }, {    576, 0x14 },
+  {  640, 0x38 }, {  768, 0x39 }, {  896, 0x3a }, {    960, 0x17 },
+  { 1024, 0x3b }, { 1152, 0x18 }, { 1280, 0x3c }, {   1536, 0x3d },
+  { 1792, 0x3e }, { 1920, 0x1b }, { 2048, 0x3f }, {   2304, 0x1c },
+  { 2560, 0x1d }, { 3072, 0x1e }, { 3840, 0x1f }, { 0xffff, 0x1f }
+};
+
+static void imx_i2c_stop(volatile imx_i2c *regs)
+{
+  regs->i2cr = IMX_I2C_I2CR_IEN;
+  regs->i2sr = 0;
+  regs->i2sr;
+}
+
+static void imx_i2c_trigger_receive(imx_i2c_bus *bus, volatile imx_i2c *regs)
+{
+  uint16_t i2cr;
+
+  i2cr = IMX_I2C_RECEIVE;
+
+  if (bus->chunk_total == 1) {
+    i2cr |= IMX_I2C_I2CR_TXAK;
+  }
+
+  regs->i2cr = i2cr;
+  regs->i2dr;
+}
+
+static void imx_i2c_done(imx_i2c_bus *bus, int eno)
+{
+  /*
+   * Generates a stop in case of transmit, otherwise, only disables interrupts
+   * (IMX_I2C_I2CR_MSTA is already cleared).
+   */
+  imx_i2c_stop(bus->regs);
+
+  bus->eno = eno;
+  rtems_event_transient_send(bus->task_id);
+}
+
+static const i2c_msg *imx_i2c_msg_inc(imx_i2c_bus *bus)
+{
+  const i2c_msg *next;
+
+  next = bus->msg + 1;
+  bus->msg = next;
+  --bus->msg_todo;
+  return next;
+}
+
+static void imx_i2c_msg_inc_and_set_buf(imx_i2c_bus *bus)
+{
+  const i2c_msg *next;
+
+  next = imx_i2c_msg_inc(bus);
+  bus->buf_todo = next->len;
+  bus->buf = next->buf;
+}
+
+static void imx_i2c_buf_inc(imx_i2c_bus *bus)
+{
+  ++bus->buf;
+  --bus->buf_todo;
+  ++bus->chunk_done;
+}
+
+static void imx_i2c_buf_push(imx_i2c_bus *bus, uint8_t c)
+{
+  while (true) {
+    if (bus->buf_todo > 0) {
+      bus->buf[0] = c;
+      imx_i2c_buf_inc(bus);
+      break;
+    }
+
+    imx_i2c_msg_inc_and_set_buf(bus);
+  }
+}
+
+static uint8_t imx_i2c_buf_pop(imx_i2c_bus *bus)
+{
+  while (true) {
+    if (bus->buf_todo > 0) {
+      uint8_t c;
+
+      c = bus->buf[0];
+      imx_i2c_buf_inc(bus);
+      return c;
+    }
+
+    imx_i2c_msg_inc_and_set_buf(bus);
+  }
+}
+
+RTEMS_STATIC_ASSERT(I2C_M_RD == 1, imx_i2c_read_flag);
+
+static void imx_i2c_setup_chunk(imx_i2c_bus *bus, volatile imx_i2c *regs)
+{
+  while (true) {
+    const i2c_msg *msg;
+    int flags;
+    int can_continue;
+    uint32_t i;
+
+    if (bus->msg_todo == 0) {
+      imx_i2c_done(bus, 0);
+      break;
+    }
+
+    msg = bus->msg;
+    flags = msg->flags;
+
+    bus->read = (flags & I2C_M_RD) != 0;
+    bus->start = (flags & I2C_M_NOSTART) == 0;
+    bus->chunk_total = msg->len;
+    bus->chunk_done = 0;
+    bus->buf_todo = msg->len;
+    bus->buf = msg->buf;
+
+    can_continue = (flags & I2C_M_RD) | I2C_M_NOSTART;
+
+    for (i = 1; i < bus->msg_todo; ++i) {
+      if ((msg[i].flags & (I2C_M_RD | I2C_M_NOSTART)) != can_continue) {
+        break;
+      }
+
+      bus->chunk_total += msg[i].len;
+    }
+
+    if (bus->start) {
+      regs->i2cr = IMX_I2C_TRANSMIT | bus->restart;
+      regs->i2dr = (uint8_t) ((msg->addr << 1) | (flags & I2C_M_RD));
+      bus->restart = IMX_I2C_I2CR_RSTA;
+      break;
+    } else if (bus->chunk_total > 0) {
+      if (bus->read) {
+        imx_i2c_trigger_receive(bus, regs);
+      } else {
+        regs->i2cr = IMX_I2C_TRANSMIT;
+        regs->i2dr = imx_i2c_buf_pop(bus);
+      }
+
+      break;
+    } else {
+      ++bus->msg;
+      --bus->msg_todo;
+    }
+  }
+}
+
+static void imx_i2c_transfer_complete(
+  imx_i2c_bus *bus,
+  volatile imx_i2c *regs,
+  uint16_t i2sr
+)
+{
+  if (bus->start) {
+    bus->start = false;
+
+    if ((i2sr & IMX_I2C_I2SR_RXAK) != 0) {
+      imx_i2c_done(bus, EIO);
+      return;
+    }
+
+    if (bus->read) {
+      imx_i2c_trigger_receive(bus, regs);
+      return;
+    }
+  }
+
+  if (bus->chunk_done < bus->chunk_total) {
+    if (bus->read) {
+      if (bus->chunk_done + 2 == bus->chunk_total) {
+        /* Receive second last byte with NACK */
+        regs->i2cr = IMX_I2C_RECEIVE | IMX_I2C_I2CR_TXAK;
+      } else if (bus->chunk_done + 1 == bus->chunk_total) {
+        /* Receive last byte with STOP */
+        bus->restart = 0;
+        regs->i2cr = (IMX_I2C_RECEIVE | IMX_I2C_I2CR_TXAK)
+          & ~IMX_I2C_I2CR_MSTA;
+      }
+
+      imx_i2c_buf_push(bus, (uint8_t) regs->i2dr);
+
+      if (bus->chunk_done == bus->chunk_total) {
+        imx_i2c_msg_inc(bus);
+        imx_i2c_setup_chunk(bus, regs);
+      }
+    } else {
+      if (bus->chunk_done > 0 && (i2sr & IMX_I2C_I2SR_RXAK) != 0) {
+        imx_i2c_done(bus, EIO);
+        return;
+      }
+
+      regs->i2dr = imx_i2c_buf_pop(bus);
+    }
+  } else {
+    imx_i2c_msg_inc(bus);
+    imx_i2c_setup_chunk(bus, regs);
+  }
+}
+
+static void imx_i2c_interrupt(void *arg)
+{
+  imx_i2c_bus *bus;
+  volatile imx_i2c *regs;
+  uint16_t i2sr;
+
+  bus = arg;
+  regs = bus->regs;
+
+  i2sr = regs->i2sr;
+  regs->i2sr = 0;
+
+  if ((i2sr & (IMX_I2C_I2SR_IAL | IMX_I2C_I2SR_ICF)) == IMX_I2C_I2SR_ICF) {
+    imx_i2c_transfer_complete(bus, regs, i2sr);
+  } else {
+    imx_i2c_done(bus, EIO);
+  }
+}
+
+static int imx_i2c_wait_for_not_busy(volatile imx_i2c *regs)
+{
+  rtems_interval timeout;
+  bool before;
+
+  if ((regs->i2sr & IMX_I2C_I2SR_IBB) == 0) {
+    return 0;
+  }
+
+  timeout = rtems_clock_tick_later(10);
+
+  do {
+    before = rtems_clock_tick_before(timeout);
+
+    if ((regs->i2sr & IMX_I2C_I2SR_IBB) == 0) {
+      return 0;
+    }
+  } while (before);
+
+  return ETIMEDOUT;
+}
+
+static int imx_i2c_transfer(i2c_bus *base, i2c_msg *msgs, uint32_t n)
+{
+  imx_i2c_bus *bus;
+  int supported_flags;
+  uint32_t i;
+  volatile imx_i2c *regs;
+  int eno;
+  rtems_status_code sc;
+
+  supported_flags = I2C_M_RD;
+
+  for (i = 0; i < n; ++i) {
+    if ((msgs[i].flags & ~supported_flags) != 0) {
+      return -EINVAL;
+    }
+
+    supported_flags |= I2C_M_NOSTART;
+  }
+
+  bus = (imx_i2c_bus *) base;
+  regs = bus->regs;
+
+  eno = imx_i2c_wait_for_not_busy(regs);
+  if (eno != 0) {
+    return -eno;
+  }
+
+  bus->msg_todo = n;
+  bus->msg = &msgs[0];
+  bus->restart = 0;
+  bus->task_id = rtems_task_self();
+  bus->eno = 0;
+
+  regs->i2sr = 0;
+  imx_i2c_setup_chunk(bus, regs);
+
+  sc = rtems_event_transient_receive(RTEMS_WAIT, bus->base.timeout);
+  if (sc != RTEMS_SUCCESSFUL) {
+    imx_i2c_stop(bus->regs);
+    rtems_event_transient_clear();
+    return -ETIMEDOUT;
+  }
+
+  return -bus->eno;
+}
+
+static int imx_i2c_set_clock(i2c_bus *base, unsigned long clock)
+{
+  imx_i2c_bus *bus;
+  uint32_t ipg_clock;
+  uint16_t div;
+  size_t i;
+  const imx_i2c_clock_divisor *clock_divisor;
+
+  bus = (imx_i2c_bus *) base;
+  ipg_clock = imx_ccm_ipg_hz();
+  div = (uint16_t) ((ipg_clock + clock - 1) / clock);
+
+  for (i = 0; i < RTEMS_ARRAY_SIZE(imx_i2c_clock_divisor_table); ++i) {
+    clock_divisor = &imx_i2c_clock_divisor_table[i];
+
+    if (clock_divisor->divisor >= div) {
+      break;
+    }
+  }
+
+  bus->regs->ifdr = clock_divisor->ifdr;
+  return 0;
+}
+
+static void imx_i2c_destroy(i2c_bus *base)
+{
+  imx_i2c_bus *bus;
+
+  bus = (imx_i2c_bus *) base;
+  rtems_interrupt_handler_remove(bus->irq, imx_i2c_interrupt, bus);
+  i2c_bus_destroy_and_free(&bus->base);
+}
+
+static int imx_i2c_init(imx_i2c_bus *bus)
+{
+  rtems_status_code sc;
+
+  imx_i2c_set_clock(&bus->base, I2C_BUS_CLOCK_DEFAULT);
+  bus->regs->i2cr = IMX_I2C_I2CR_IEN;
+
+  sc = rtems_interrupt_handler_install(
+    bus->irq,
+    "I2C",
+    RTEMS_INTERRUPT_UNIQUE,
+    imx_i2c_interrupt,
+    bus
+  );
+  if (sc != RTEMS_SUCCESSFUL) {
+    return EAGAIN;
+  }
+
+  return 0;
+}
+
+int i2c_bus_register_imx(const char *bus_path, const char *alias)
+{
+  const void *fdt;
+  int node;
+  imx_i2c_bus *bus;
+  int eno;
+
+  fdt = bsp_fdt_get();
+  alias = fdt_get_alias(fdt, alias);
+
+  if (alias == NULL) {
+    rtems_set_errno_and_return_minus_one(ENXIO);
+  }
+
+  bus = (imx_i2c_bus *) i2c_bus_alloc_and_init(sizeof(*bus));
+  if (bus == NULL){
+    return -1;
+  }
+
+  node = fdt_path_offset(fdt, alias);
+  bus->regs = imx_get_reg_of_node(fdt, node);
+  bus->irq = imx_get_irq_of_node(fdt, node, 0);
+
+  eno = imx_i2c_init(bus);
+  if (eno != 0) {
+    (*bus->base.destroy)(&bus->base);
+    rtems_set_errno_and_return_minus_one(eno);
+  }
+
+  bus->base.transfer = imx_i2c_transfer;
+  bus->base.set_clock = imx_i2c_set_clock;
+  bus->base.destroy = imx_i2c_destroy;
+
+  return i2c_bus_register(&bus->base, bus_path);
+}
diff --git a/c/src/lib/libbsp/arm/imx/include/bsp.h b/c/src/lib/libbsp/arm/imx/include/bsp.h
index 08b3127dba..e4debf2a14 100644
--- a/c/src/lib/libbsp/arm/imx/include/bsp.h
+++ b/c/src/lib/libbsp/arm/imx/include/bsp.h
@@ -49,6 +49,17 @@ rtems_vector_number imx_get_irq_of_node(
   size_t index
 );
 
+/**
+ * @brief Registers an IMX I2C bus driver.
+ *
+ * @param[in] bus_path The I2C bus driver device path, e.g. "/dev/i2c-0".
+ * @param[in] alias_or_path The FDT alias or path, e.g. "i2c0".
+ *
+ * @retval 0 Successful operation.
+ * @retval -1 An error occurred.  The errno is set to indicate the error.
+ */
+int i2c_bus_register_imx(const char *bus_path, const char *alias_or_path);
+
 #ifdef __cplusplus
 }
 #endif /* __cplusplus */