[U-Boot-Users] [PATCH 2/2] Multi-bus I2C implementation of MPC834x

[Timur Tabi <timur@freescale.com>]

Ben Warren wrote:
> Hello,
> 
> Attached is a patch implementing multiple I2C buses on the MPC834x CPU
> family and the MPC8349EMDS board in particular.

Here's my patch which does the same thing.

CHANGELOG:

* The current support for dual I2C busses is specific to the MPC 8349.  This patch
   makes it more generic.  If two I2C busses are present (i.e. CFG_I2C2_OFFSET is
   defined), then the macro 'I2C' becomes a variable.  Any code which needs to
   reference the I2C bus should make sure that 'I2C' points to the right bus before
   calling an i2c_* function.  i2c_init() and do_i2c_probe() have been updated to
   automatically process both busses.  And lastly, some hard-code constants have
   been replaced by macros.

Signed-off-by: Timur Tabi <timur@freescale.com>

---

  board/mpc8349emds/pci.c |    2 +-
  common/cmd_i2c.c        |   29 ++++++++++++++++++++++++-----
  cpu/mpc83xx/i2c.c       |   35 +++++++++++++++++++++++++++++------
  include/asm-ppc/i2c.h   |    9 ++++-----
  4 files changed, 58 insertions(+), 17 deletions(-)

4fa4904374e01e31ea155dbe340d72abd944617a
diff --git a/board/mpc8349emds/pci.c b/board/mpc8349emds/pci.c
index 63e4405..e91bfef 100644
--- a/board/mpc8349emds/pci.c
+++ b/board/mpc8349emds/pci.c
@@ -72,7 +72,7 @@ pib_init(void)
      /*
       * Assign PIB PMC slot to desired PCI bus
       */
-    mpc8349_i2c = (i2c_t*)(CFG_IMMRBAR + CFG_I2C2_OFFSET);
+    I2C = (i2c_t*) (CFG_IMMRBAR + CFG_I2C2_OFFSET);
      i2c_init(CFG_I2C_SPEED, CFG_I2C_SLAVE);

      val8 = 0;
diff --git a/common/cmd_i2c.c b/common/cmd_i2c.c
index c543bb5..9f0980b 100644
--- a/common/cmd_i2c.c
+++ b/common/cmd_i2c.c
@@ -529,11 +529,7 @@ mod_i2c_mem(cmd_tbl_t *cmdtp, int incrfl
      return 0;
  }

-/*
- * Syntax:
- *    iprobe {addr}{.0, .1, .2}
- */
-int do_i2c_probe (cmd_tbl_t *cmdtp, int flag, int argc, char *argv[])
+static void _do_i2c_probe(void)
  {
      int j;
  #if defined(CFG_I2C_NOPROBES)
@@ -565,6 +561,29 @@ int do_i2c_probe (cmd_tbl_t *cmdtp, int
          printf(" %02X", i2c_no_probes[k] );
      putc ('\n');
  #endif
+}
+
+/*
+ * Syntax:
+ *    iprobe {addr}{.0, .1, .2}
+ */
+int do_i2c_probe(cmd_tbl_t *cmdtp, int flag, int argc, char *argv[])
+{
+#ifdef CFG_I2C2_OFFSET
+
+/* If we have two I2C busses, then we need to probe each one separately.
+   Note that if an I2C address is defined in i2c_no_probes[], we skip it
+   on both busses.
+*/
+    printf("I2C1 ");
+    I2C = (i2c_t *) (CFG_IMMRBAR + CFG_I2C_OFFSET);
+    _do_i2c_probe();
+
+    printf("I2C2 ");
+    I2C = (i2c_t *) (CFG_IMMRBAR + CFG_I2C2_OFFSET);
+#endif
+
+    _do_i2c_probe();

      return 0;
  }
diff --git a/cpu/mpc83xx/i2c.c b/cpu/mpc83xx/i2c.c
index 70450f9..308a65d 100644
--- a/cpu/mpc83xx/i2c.c
+++ b/cpu/mpc83xx/i2c.c
@@ -41,21 +41,30 @@
  #include <i2c.h>
  #include <asm/i2c.h>

-#if defined(CONFIG_MPC8349EMDS) || defined(CONFIG_TQM834X)
-i2c_t * mpc8349_i2c = (i2c_t*)(CFG_IMMRBAR + CFG_I2C_OFFSET);
+#ifdef CFG_I2C2_OFFSET
+/*
+To configure DDR RAM, we need to query the I2C bus.  Since RAM hasn't
+been initialized, U-Boot has not been copied yet to RAM.  That means that
+the global variable 'I2C' is located in flash, which means it can't be
+modified.  Therefore, 'I2C' needs to be initialized to the I2C bus that
+DDR is on.
+
+CFG_I2C_DDR_OFFSET is the offset of the I2C bus that DDR is using.  It
+should be set to either CFG_I2C_OFFSET or CFG_I2C2_OFFSET.
+*/
+volatile i2c_t *I2C = (i2c_t *) (CFG_IMMRBAR + CFG_I2C_DDR_OFFSET);
  #endif

-void
-i2c_init(int speed, int slaveadd)
+static void _i2c_init(int slaveadd)
  {
      /* stop I2C controller */
      writeb(0x00 , &I2C->cr);

      /* set clock */
-    writeb(0x3f, &I2C->fdr);
+    writeb(IC2_FDR, &I2C->fdr);

      /* set default filter */
-    writeb(0x10,&I2C->dfsrr);
+    writeb(I2C_CR_MTX, &I2C->dfsrr);

      /* write slave address */
      writeb(slaveadd, &I2C->adr);
@@ -67,6 +76,20 @@ i2c_init(int speed, int slaveadd)
      writeb(I2C_CR_MEN, &I2C->cr);
  }

+void
+i2c_init(int speed, int slaveadd)
+{
+#ifdef CFG_I2C2_OFFSET
+    /* If it exists, initialize the 2nd I2C bus */
+    I2C = (i2c_t *) (CFG_IMMRBAR + CFG_I2C_OFFSET);
+    _i2c_init(slaveadd);
+
+    I2C = (i2c_t *) (CFG_IMMRBAR + CFG_I2C2_OFFSET);
+#endif
+    _i2c_init(slaveadd);
+
+}
+
  static __inline__ int
  i2c_wait4bus (void)
  {
diff --git a/include/asm-ppc/i2c.h b/include/asm-ppc/i2c.h
index 1680d3a..bd6a51d 100644
--- a/include/asm-ppc/i2c.h
+++ b/include/asm-ppc/i2c.h
@@ -87,14 +87,13 @@ typedef struct i2c
  #error CFG_I2C_OFFSET is not defined in /include/configs/${BOARD}.h
  #endif

-#if defined(CONFIG_MPC8349EMDS) || defined(CONFIG_TQM834X)
+#ifdef CFG_I2C2_OFFSET
  /*
- * MPC8349 have two i2c bus
+ * If we have two I2C busses, then 'I2C' should be a variable, not a constant.
   */
-extern i2c_t * mpc8349_i2c;
-#define I2C mpc8349_i2c
+extern volatile i2c_t *I2C;
  #else
-#define I2C ((i2c_t*)(CFG_IMMRBAR + CFG_I2C_OFFSET))
+#define I2C ((i2c_t*) (CFG_IMMRBAR + CFG_I2C_OFFSET))
  #endif

  #define I2C_READ  1
-- 
1.2.4

-- 
Timur Tabi
Linux Kernel Developer @ Freescale