Gigabeat S: Implement i2c driver - transmit works but no testing of receiving which will get a chance later. Add some seeds for codec driver. Correct a few #defines.

git-svn-id: svn://svn.rockbox.org/rockbox/trunk@17254 a1c6a512-1295-4272-9138-f99709370657

10 files changed, 571 insertions, 33 deletions

diff --git a/firmware/SOURCES b/firmware/SOURCES
index 879800e..5083357 100644
--- a/firmware/SOURCES
+++ b/firmware/SOURCES
@@ -210,7 +210,9 @@ drivers/mas.c
 drivers/audio/uda1380.c
 #elif defined(HAVE_WM8751)
 drivers/audio/wm8751.c
-#elif defined(HAVE_WM8975) || defined(HAVE_WM8978)
+#elif defined(HAVE_WM8978)
+drivers/audio/wm8978.c
+#elif defined(HAVE_WM8975)
 drivers/audio/wm8975.c
 #elif defined(HAVE_WM8985)
 drivers/audio/wm8985.c
diff --git a/firmware/drivers/audio/wm8978.c b/firmware/drivers/audio/wm8978.c
new file mode 100644
index 0000000..01f3d33
--- /dev/null
+++ b/firmware/drivers/audio/wm8978.c
@@ -0,0 +1,60 @@
+/***************************************************************************
+ *             __________               __   ___.
+ *   Open      \______   \ ____   ____ |  | _\_ |__   _______  ___
+ *   Source     |       _//  _ \_/ ___\|  |/ /| __ \ /  _ \  \/  /
+ *   Jukebox    |    |   (  <_> )  \___|    < | \_\ (  <_> > <  <
+ *   Firmware   |____|_  /\____/ \___  >__|_ \|___  /\____/__/\_ \
+ *                     \/            \/     \/    \/            \/
+ * $Id$
+ *
+ * Copyright (C) 2008 by Michael Sevakis
+ *
+ * Driver for WM8978 audio codec 
+ *
+ * All files in this archive are subject to the GNU General Public License.
+ * See the file COPYING in the source tree root for full license agreement.
+ *
+ * This software is distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY
+ * KIND, either express or implied.
+ *
+ ****************************************************************************/
+#include "config.h"
+#include "system.h"
+#include "audiohw.h"
+#include "wmcodec.h"
+#include "audio.h"
+
+const struct sound_settings_info audiohw_settings[] = {
+    [SOUND_VOLUME]        = {"dB", 0,  1, -58,   6, -25},
+    [SOUND_BASS]          = {"dB", 0,  1, -12,  12,   0},
+    [SOUND_TREBLE]        = {"dB", 0,  1, -12,  12,   0},
+    [SOUND_BALANCE]       = {"%",  0,  1,-100, 100,   0},
+    [SOUND_CHANNELS]      = {"",   0,  1,   0,   5,   0},
+    [SOUND_STEREO_WIDTH]  = {"%",  0,  5,   0, 250, 100},
+    [SOUND_LEFT_GAIN]     = {"dB", 1,  1,-128,  96,   0},
+    [SOUND_RIGHT_GAIN]    = {"dB", 1,  1,-128,  96,   0},
+    [SOUND_MIC_GAIN]      = {"dB", 1,  1,-128, 108,  16},
+#if 0
+    [SOUND_BASS_CUTOFF]   = {"",   0,  1,   1,   4,   1},
+    [SOUND_TREBLE_CUTOFF] = {"",   0,  1,   1,   4,   1},
+#endif
+};
+
+void audiohw_preinit(void)
+{
+    wmcodec_write(WM8978_SOFTWARE_RESET, 0);
+}
+
+void audiohw_postinit(void)
+{
+    sleep(HZ);
+}
+
+void audiohw_close(void)
+{
+}
+
+void audiohw_mute(bool mute)
+{
+    (void)mute;
+}
diff --git a/firmware/export/audiohw.h b/firmware/export/audiohw.h
index 73c50b8..190fcca 100644
--- a/firmware/export/audiohw.h
+++ b/firmware/export/audiohw.h
@@ -27,7 +27,9 @@
 #include "uda1380.h"
 #elif defined(HAVE_WM8751)
 #include "wm8751.h"
-#elif defined(HAVE_WM8975) || defined(HAVE_WM8978)
+#elif defined(HAVE_WM8978)
+#include "wm8978.h"
+#elif defined(HAVE_WM8975)
 #include "wm8975.h"
 #elif defined(HAVE_WM8985)
 #include "wm8985.h"
@@ -109,7 +111,14 @@ extern const struct sound_settings_info audiohw_settings[];
 void audiohw_init(void);
 
 /**
- * Do some stuff (codec related) after audiohw_init.
+ * Do initial audio codec setup.
+ */
+void audiohw_preinit(void);
+
+/**
+ * Do some stuff (codec related) after audiohw_init that needs to be
+ * delayed such as enabling outputs to prevent popping. This lets
+ * other inits in the system complete in the meantime.
  */
 void audiohw_postinit(void);
 
diff --git a/firmware/export/config-gigabeat-s.h b/firmware/export/config-gigabeat-s.h
index 6eb57b2..3e36e0c 100644
--- a/firmware/export/config-gigabeat-s.h
+++ b/firmware/export/config-gigabeat-s.h
@@ -66,10 +66,9 @@
 /* The number of bytes reserved for loadable plugins */
 #define PLUGIN_BUFFER_SIZE 0x80000
 
-/* Define this if you have the WM8975 audio codec */
+/* Define this if you have the WM8978 audio codec */
 #define HAVE_WM8978
 
-
 #define HW_SAMPR_CAPS (SAMPR_CAP_88 | SAMPR_CAP_44 | SAMPR_CAP_22 | \
                        SAMPR_CAP_11)
 
@@ -85,8 +84,9 @@
 /* Define this if you want to use coldfire's i2c interface */
 #define CONFIG_I2C I2C_IMX31L
 
-/* Define the bitmask of serial interface modules (CSPI) used */
+/* Define the bitmask of modules used */
 #define SPI_MODULE_MASK (USE_CSPI2_MODULE)
+#define I2C_MODULE_MASK (USE_I2C1_MODULE)
 
 /* Define this if target has an additional number of threads specific to it */
 #define TARGET_EXTRA_THREADS 1
diff --git a/firmware/export/imx31l.h b/firmware/export/imx31l.h
index aea4b9e..777fa69 100755
--- a/firmware/export/imx31l.h
+++ b/firmware/export/imx31l.h
@@ -49,7 +49,7 @@
 #define ETB_SLOT4_BASE_ADDR     0x43F10000
 #define ETB_SLOT5_BASE_ADDR     0x43F14000
 #define ECT_CTIO_BASE_ADDR      0x43F18000
-#define I2C_BASE_ADDR           0x43F80000
+#define I2C1_BASE_ADDR          0x43F80000
 #define I2C3_BASE_ADDR          0x43F84000
 #define OTG_BASE_ADDR           0x43F88000
 #define ATA_BASE_ADDR           0x43F8C000
@@ -628,6 +628,112 @@
 #define CSPI_TESTREG_SWAP               (1 << 15)
 #define CSPI_TESTREG_LBC                (1 << 14)
 
+/* I2C */
+#define I2C_IADR1               (*(REG16_PTR_T)(I2C1_BASE_ADDR+0x0))
+#define I2C_IFDR1               (*(REG16_PTR_T)(I2C1_BASE_ADDR+0x4))
+#define I2C_I2CR1               (*(REG16_PTR_T)(I2C1_BASE_ADDR+0x8))
+#define I2C_I2SR1               (*(REG16_PTR_T)(I2C1_BASE_ADDR+0xC))
+#define I2C_I2DR1               (*(REG16_PTR_T)(I2C1_BASE_ADDR+0x10))
+
+#define I2C_IADR2               (*(REG16_PTR_T)(I2C2_BASE_ADDR+0x0))
+#define I2C_IFDR2               (*(REG16_PTR_T)(I2C2_BASE_ADDR+0x4))
+#define I2C_I2CR2               (*(REG16_PTR_T)(I2C2_BASE_ADDR+0x8))
+#define I2C_I2SR2               (*(REG16_PTR_T)(I2C2_BASE_ADDR+0xC))
+#define I2C_I2DR2               (*(REG16_PTR_T)(I2C2_BASE_ADDR+0x10))
+
+#define I2C_IADR3               (*(REG16_PTR_T)(I2C3_BASE_ADDR+0x0))
+#define I2C_IFDR3               (*(REG16_PTR_T)(I2C3_BASE_ADDR+0x4))
+#define I2C_I2CR3               (*(REG16_PTR_T)(I2C3_BASE_ADDR+0x8))
+#define I2C_I2SR3               (*(REG16_PTR_T)(I2C3_BASE_ADDR+0xC))
+#define I2C_I2DR3               (*(REG16_PTR_T)(I2C3_BASE_ADDR+0x10))
+
+    /* IADR - [7:1] Address */
+
+    /* IFDR */
+#define I2C_IFDR_DIV30           0x00
+#define I2C_IFDR_DIV32           0x01
+#define I2C_IFDR_DIV36           0x02
+#define I2C_IFDR_DIV42           0x03
+#define I2C_IFDR_DIV48           0x04
+#define I2C_IFDR_DIV52           0x05
+#define I2C_IFDR_DIV60           0x06
+#define I2C_IFDR_DIV72           0x07
+#define I2C_IFDR_DIV80           0x08
+#define I2C_IFDR_DIV88           0x09
+#define I2C_IFDR_DIV104          0x0a
+#define I2C_IFDR_DIV128          0x0b
+#define I2C_IFDR_DIV144          0x0c
+#define I2C_IFDR_DIV160          0x0d
+#define I2C_IFDR_DIV192          0x0e
+#define I2C_IFDR_DIV240          0x0f
+#define I2C_IFDR_DIV288          0x10
+#define I2C_IFDR_DIV320          0x11
+#define I2C_IFDR_DIV384          0x12
+#define I2C_IFDR_DIV480          0x13
+#define I2C_IFDR_DIV576          0x14
+#define I2C_IFDR_DIV640          0x15
+#define I2C_IFDR_DIV768          0x16
+#define I2C_IFDR_DIV960          0x17
+#define I2C_IFDR_DIV1152         0x18
+#define I2C_IFDR_DIV1280         0x19
+#define I2C_IFDR_DIV1536         0x1a
+#define I2C_IFDR_DIV1920         0x1b
+#define I2C_IFDR_DIV2304         0x1c
+#define I2C_IFDR_DIV2560         0x1d
+#define I2C_IFDR_DIV3072         0x1e
+#define I2C_IFDR_DIV3840         0x1f
+#define I2C_IFDR_DIV22           0x20
+#define I2C_IFDR_DIV24           0x21
+#define I2C_IFDR_DIV26           0x22
+#define I2C_IFDR_DIV28           0x23
+#define I2C_IFDR_DIV32_2         0x24
+#define I2C_IFDR_DIV36_2         0x25
+#define I2C_IFDR_DIV40           0x26
+#define I2C_IFDR_DIV44           0x27
+#define I2C_IFDR_DIV48_2         0x28
+#define I2C_IFDR_DIV56           0x29
+#define I2C_IFDR_DIV64           0x2a
+#define I2C_IFDR_DIV72_2         0x2b
+#define I2C_IFDR_DIV80_2         0x2c
+#define I2C_IFDR_DIV96           0x2d
+#define I2C_IFDR_DIV112          0x2e
+#define I2C_IFDR_DIV128_2        0x2f
+#define I2C_IFDR_DIV160_2        0x30
+#define I2C_IFDR_DIV192_2        0x31
+#define I2C_IFDR_DIV224          0x32
+#define I2C_IFDR_DIV256          0x33
+#define I2C_IFDR_DIV320_2        0x34
+#define I2C_IFDR_DIV384_2        0x35
+#define I2C_IFDR_DIV448          0x36
+#define I2C_IFDR_DIV512          0x37
+#define I2C_IFDR_DIV640_2        0x38
+#define I2C_IFDR_DIV768_2        0x39
+#define I2C_IFDR_DIV896          0x3a
+#define I2C_IFDR_DIV1024         0x3b
+#define I2C_IFDR_DIV1280_2       0x3c
+#define I2C_IFDR_DIV1536_2       0x3d
+#define I2C_IFDR_DIV1792         0x3e
+#define I2C_IFDR_DIV2048         0x3f
+
+    /* I2CR */
+#define I2C_I2CR_IEN            (1 << 7)
+#define I2C_I2CR_IIEN           (1 << 6)
+#define I2C_I2CR_MSTA           (1 << 5)
+#define I2C_I2CR_MTX            (1 << 4)
+#define I2C_I2CR_TXAK           (1 << 3)
+#define I2C_I2CR_RSATA          (1 << 2)
+
+    /* I2SR */
+#define I2C_I2SR_ICF            (1 << 7)
+#define I2C_I2SR_IAAS           (1 << 6)
+#define I2C_I2SR_IBB            (1 << 5)
+#define I2C_I2SR_IAL            (1 << 4)
+#define I2C_I2SR_SRW            (1 << 2)
+#define I2C_I2SR_IIF            (1 << 1)
+#define I2C_I2SR_RXAK           (1 << 0)
+
+    /* I2DR - [7:0] Data */
+
 /* RTC */
 #define RTC_HOURMIN             (*(REG32_PTR_T)(RTC_BASE_ADDR+0x00))
 #define RTC_SECONDS             (*(REG32_PTR_T)(RTC_BASE_ADDR+0x04))
diff --git a/firmware/export/wm8978.h b/firmware/export/wm8978.h
index 3a1eb62..aca1250 100644
--- a/firmware/export/wm8978.h
+++ b/firmware/export/wm8978.h
@@ -21,6 +21,9 @@
 #ifndef _WM8978_H
 #define _WM8978_H
 
+#define VOLUME_MIN -570
+#define VOLUME_MAX 60
+
 #define WM8978_I2C_ADDR 0x34
 
 /* Registers */
@@ -142,7 +145,7 @@
     #define WM8978_DAC_COMP_U_LAW           (2 << 3)
     #define WM8978_DAC_COMP_A_LAW           (3 << 3)
 #define WM8978_ADC_COMP                     (3 << 1)
-    #define WM8978_DAC_COMP_OFF             (0 << 1)
+    #define WM8978_ADC_COMP_OFF             (0 << 1)
     #define WM8978_ADC_COMP_U_LAW           (2 << 1)
     #define WM8978_ADC_COMP_A_LAW           (3 << 1)
 #define WM8978_LOOPBACK                     (1 << 0)
@@ -159,12 +162,12 @@
     #define WM8978_MCLKDIV_8                (6 << 5)
     #define WM8978_MCLKDIV_12               (7 << 5)
 #define WM8978_BCLKDIV                      (7 << 2)
-    #define WM8978_MCLKDIV_1                (0 << 2)
-    #define WM8978_MCLKDIV_2                (1 << 2)
-    #define WM8978_MCLKDIV_4                (2 << 2)
-    #define WM8978_MCLKDIV_8                (3 << 2)
-    #define WM8978_MCLKDIV_16               (4 << 2)
-    #define WM8978_MCLKDIV_32               (5 << 2)
+    #define WM8978_BCLKDIV_1                (0 << 2)
+    #define WM8978_BCLKDIV_2                (1 << 2)
+    #define WM8978_BCLKDIV_4                (2 << 2)
+    #define WM8978_BCLKDIV_8                (3 << 2)
+    #define WM8978_BCLKDIV_16               (4 << 2)
+    #define WM8978_BCLKDIV_32               (5 << 2)
 #define WM8978_MS                           (1 << 0)
 
 /* WM8978_ADDITIONAL_CTRL (0x07) */
diff --git a/firmware/target/arm/imx31/gigabeat-s/i2c-imx31.c b/firmware/target/arm/imx31/gigabeat-s/i2c-imx31.c
index 54ddaa7..ccd9efb 100644
--- a/firmware/target/arm/imx31/gigabeat-s/i2c-imx31.c
+++ b/firmware/target/arm/imx31/gigabeat-s/i2c-imx31.c
@@ -7,7 +7,7 @@
  *                     \/            \/     \/    \/            \/
  * $Id$
  *
- * Copyright (C) 2007 by Michael Sevakis
+ * Copyright (C) 2008 by Michael Sevakis
  *
  * All files in this archive are subject to the GNU General Public License.
  * See the file COPYING in the source tree root for full license agreement.
@@ -16,38 +16,321 @@
  * KIND, either express or implied.
  *
  ****************************************************************************/
+#include <stdlib.h>
+#include "config.h"
 #include "system.h"
+#include "kernel.h"
+#include "avic-imx31.h"
+#include "clkctl-imx31.h"
 #include "i2c-imx31.h"
 
-#if 0
-static int i2c_getack(void)
+/* Forward interrupt handler declarations */
+#if (I2C_MODULE_MASK & USE_I2C1_MODULE)
+static __attribute__((interrupt("IRQ"))) void I2C1_HANDLER(void);
+#endif
+#if (I2C_MODULE_MASK & USE_I2C2_MODULE)
+static __attribute__((interrupt("IRQ"))) void I2C2_HANDLER(void);
+#endif
+#if (I2C_MODULE_MASK & USE_I2C3_MODULE)
+static __attribute__((interrupt("IRQ"))) void I2C3_HANDLER(void);
+#endif
+
+static struct i2c_module_descriptor
 {
-    return 0;
+    struct i2c_map *base;     /* Module base address */
+    enum IMX31_CG_LIST cg;    /* Clock gating index */
+    enum IMX31_INT_LIST ints; /* Module interrupt number */
+    int enable;               /* Enable count */
+    void (*handler)(void);    /* Module interrupt handler */
+    struct mutex m;           /* Node mutual-exclusion */
+    struct wakeup w;          /* I2C done signal */
+    unsigned char *addr_data; /* Additional addressing data */
+    int addr_count;           /* Addressing byte count */
+    unsigned char *data;      /* TX/RX buffer (actual data) */
+    int data_count;           /* TX/RX byte count */
+    unsigned char addr;       /* Address + r/w bit */
+} i2c_descs[I2C_NUM_I2C] =
+{
+#if (I2C_MODULE_MASK & USE_I2C1_MODULE)
+    {
+        .base    = (struct i2c_map *)I2C1_BASE_ADDR,
+        .cg      = CG_I2C1,
+        .ints    = I2C1,
+        .handler = I2C1_HANDLER,
+    },
+#endif
+#if (I2C_MODULE_MASK & USE_I2C2_MODULE)
+    {
+        .base    = (struct i2c_map *)I2C2_BASE_ADDR,
+        .cg      = CG_I2C2,
+        .ints    = I2C2,
+        .handler = I2C2_HANDLER,
+    },
+#endif
+#if (I2C_MODULE_MASK & USE_I2C3_MODULE)
+    {
+        .base    = (struct i2c_map *)I2C3_BASE_ADDR,
+        .cg      = CG_I2C3,
+        .ints    = I2C3,
+        .handler = I2C3_HANDLER,
+    },
+#endif
+};
+
+static void i2c_interrupt(enum i2c_module_number i2c)
+{
+    struct i2c_module_descriptor *const desc = &i2c_descs[i2c];
+    struct i2c_map * const base = desc->base;
+    uint16_t i2sr = base->i2sr;
+
+    base->i2sr = i2sr & ~I2C_I2SR_IIF; /* Clear IIF */
+
+    if (desc->addr_count >= 0)
+    {
+        /* ADDR cycle - either done or more to send */
+        if ((i2sr & I2C_I2SR_RXAK) != 0)
+        {
+            goto i2c_stop; /* problem */
+        }
+
+        if (--desc->addr_count < 0)
+        {
+            /* Switching to data cycle */
+            if (desc->addr & 0x1)
+            {
+                base->i2cr &= ~I2C_I2CR_MTX; /* Switch to RX mode */
+                base->i2dr;                  /* Dummy read */
+                return;
+            }
+            /* else remaining data is TX - handle below */
+            goto i2c_transmit;
+        }
+        else
+        {
+            base->i2dr = *desc->addr_data++; /* Send next addressing byte */
+            return;
+        }
+    }
+
+    if (base->i2cr & I2C_I2CR_MTX)
+    {
+i2c_transmit:
+        /* Transmitting data */
+        if ((i2sr & I2C_I2SR_RXAK) == 0 && desc->data_count > 0)
+        {
+            /* More bytes to send, got ACK from previous byte */
+            base->i2dr = *desc->data++;
+            desc->data_count--;
+            return;
+        }
+        /* else done or no ACK received */
+    }
+    else
+    {
+        /* Receiving data */
+        if (--desc->data_count > 0)
+        {
+            if (desc->data_count == 1)
+            {
+                /* 2nd to Last byte - NACK */
+                base->i2cr |= I2C_I2CR_TXAK;
+            }
+
+            *desc->data++ = base->i2dr; /* Read data from I2DR and store */
+            return;
+        }
+        else
+        {
+            /* Generate STOP signal before reading data */
+            base->i2cr &= ~(I2C_I2CR_MSTA | I2C_I2CR_IIEN);
+            *desc->data++ = base->i2dr; /* Read data from I2DR and store */
+            goto i2c_done;
+        }
+    }
+
+i2c_stop:
+    /* Generate STOP signal */
+    base->i2cr &= ~(I2C_I2CR_MSTA | I2C_I2CR_IIEN);
+i2c_done:
+    /* Signal thread we're done */
+    wakeup_signal(&desc->w);
 }
 
-static int i2c_start(void)
+#if (I2C_MODULE_MASK & USE_I2C1_MODULE)
+static __attribute__((interrupt("IRQ"))) void I2C1_HANDLER(void)
 {
-    return 0;
+    i2c_interrupt(I2C1_NUM);
 }
+#endif
+#if (I2C_MODULE_MASK & USE_I2C2_MODULE)
+static __attribute__((interrupt("IRQ"))) void I2C2_HANDLER(void)
+{
+    i2c_interrupt(I2C2_NUM);
+}
+#endif
+#if (I2C_MODULE_MASK & USE_I2C3_MODULE)
+static __attribute__((interrupt("IRQ"))) void I2C3_HANDLER(void)
+{
+    i2c_interrupt(I2C3_NUM);
+}
+#endif
 
-static void i2c_stop(void)
+static int i2c_transfer(struct i2c_node * const node,
+                        struct i2c_module_descriptor *const desc)
 {
+    struct i2c_map * const base = desc->base;
+    int count = desc->data_count;
+    uint16_t i2cr;
+
+    /* Set speed */
+    base->ifdr = node->ifdr;
+
+    /* Enable module */
+    base->i2cr = I2C_I2CR_IEN;
+
+    /* Enable Interrupt, Master */
+    i2cr = I2C_I2CR_IEN | I2C_I2CR_IIEN | I2C_I2CR_MTX;
+
+    if ((desc->addr & 0x1) && desc->data_count < 2)
+    {
+        /* Receiving less than two bytes - disable ACK generation */
+        i2cr |= I2C_I2CR_TXAK;
+    }
+
+    /* Set config */
+    base->i2cr = i2cr;
+
+    /* Generate START */
+    base->i2cr |= I2C_I2CR_MSTA;
+
+    /* Address slave (first byte sent) and begin session. */
+    base->i2dr = desc->addr;
+
+    /* Wait for transfer to complete */
+    count = (wakeup_wait(&desc->w, HZ) != OBJ_WAIT_SUCCEEDED) ?
+                -1 : (count - desc->data_count);
+    
+    /* Disable module - generate STOP if timeout */
+    base->i2cr = 0;
+
+    return count;
 }
 
-static int i2c_outb(unsigned char byte)
+int i2c_read(struct i2c_node *node, int reg,
+             unsigned char *data, int data_count)
 {
-    (void)byte;
-    return 0;
+    struct i2c_module_descriptor *const desc = &i2c_descs[node->num];
+    unsigned char ad[1];
+
+    mutex_lock(&desc->m);
+
+    desc->addr = (node->addr & 0xfe) | 0x1;  /* Slave address/rd */
+
+    if (reg >= 0)
+    {
+        /* Sub-address */
+        desc->addr_count = 1;
+        desc->addr_data = ad;
+        ad[0] = reg;
+    }
+    /* else raw read from slave */
+
+    desc->data = data;
+    desc->data_count = data_count;
+
+    data_count = i2c_transfer(node, desc);
+
+    desc->addr_count = 0; /* To eliminate zeroing elsewhere */
+
+    mutex_unlock(&desc->m);
+
+    return data_count;
 }
-#endif
 
-void i2c_write(int addr, const unsigned char *buf, int count)
+int i2c_write(struct i2c_node *node, const unsigned char *data, int data_count)
 {
-    (void)addr;
-    (void)buf;
-    (void)count;
+    struct i2c_module_descriptor *const desc = &i2c_descs[node->num];
+
+    mutex_lock(&desc->m);
+
+    desc->addr = node->addr & 0xfe; /* Slave address/wr */
+    desc->data = (unsigned char *)data;
+    desc->data_count = data_count;
+
+    data_count = i2c_transfer(node, desc);
+
+    mutex_unlock(&desc->m);
+
+    return data_count;
 }
 
 void i2c_init(void)
 {
+    int i;
+
+    /* Do one-time inits for each module that will be used - leave
+     * module disabled and unclocked until something wants it */
+    for (i = 0; i < I2C_NUM_I2C; i++)
+    {
+        struct i2c_module_descriptor *const desc = &i2c_descs[i];
+        imx31_clkctl_module_clock_gating(desc->cg, CGM_ON_ALL);
+        mutex_init(&desc->m);
+        wakeup_init(&desc->w);
+        desc->base->i2cr = 0;
+        imx31_clkctl_module_clock_gating(desc->cg, CGM_OFF);
+    }
+
+#if 0
+    /* Pad config set up by OF bootloader doesn't agree with manual but
+     * TX works at the moment - probably would't do this here either */
+    uint32_t reg = SW_PAD_CTL_CSI_PIXCLK_I2C_CLK_I2C_DAT;
+    reg &= ~0xfffff;
+    reg |= (1 << 19) | (3 << 17) | (1 << 15) | (1 << 14) |
+           (1 << 13) | (0 << 11);
+
+    reg |= (1 << 9) | (3 << 7) | (1 << 5) | (1 << 4) |
+           (1 << 3) | (0 << 1);
+
+    SW_PAD_CTL_CSI_PIXCLK_I2C_CLK_I2C_DAT = reg;
+#endif
+}
+
+void i2c_enable_node(struct i2c_node *node, bool enable)
+{
+    struct i2c_module_descriptor *const desc = &i2c_descs[node->num];
+
+    mutex_lock(&desc->m);
+
+    if (enable)
+    {
+        if (++desc->enable == 1)
+        {
+            /* First enable */
+            imx31_clkctl_module_clock_gating(desc->cg, CGM_ON_ALL);
+            avic_enable_int(desc->ints, IRQ, 7, desc->handler);
+        }
+    }
+    else
+    {
+        if (desc->enable > 0 && --desc->enable == 0)
+        {
+            /* Last enable */
+            avic_disable_int(desc->ints);
+            imx31_clkctl_module_clock_gating(desc->cg, CGM_OFF);
+        }
+    }
+
+    mutex_unlock(&desc->m);
+}
+
+void i2c_lock_node(struct i2c_node *node)
+{
+    struct i2c_module_descriptor *const desc = &i2c_descs[node->num];
+    mutex_lock(&desc->m);
+}
+
+void i2c_unlock_node(struct i2c_node *node)
+{
+    struct i2c_module_descriptor *const desc = &i2c_descs[node->num];
+    mutex_unlock(&desc->m);
 }
diff --git a/firmware/target/arm/imx31/gigabeat-s/i2c-imx31.h b/firmware/target/arm/imx31/gigabeat-s/i2c-imx31.h
index c708ebb..d6de5c4 100644
--- a/firmware/target/arm/imx31/gigabeat-s/i2c-imx31.h
+++ b/firmware/target/arm/imx31/gigabeat-s/i2c-imx31.h
@@ -16,7 +16,61 @@
  * KIND, either express or implied.
  *
  ****************************************************************************/
+#ifndef _I2C_IMX31_H_
+#define _I2C_IMX31_H_
+
+#include <stdbool.h>
+
+/* I2C module usage masks */
+#define USE_I2C1_MODULE         (1 << 0)
+#define USE_I2C2_MODULE         (1 << 1)
+#define USE_I2C3_MODULE         (1 << 2)
+
+enum i2c_module_number
+{
+    __I2C_NUM_START = -1,
+#if (I2C_MODULE_MASK & USE_I2C1_MODULE)
+    I2C1_NUM,
+#endif
+#if (I2C_MODULE_MASK & USE_I2C2_MODULE)
+    I2C2_NUM,
+#endif
+#if (I2C_MODULE_MASK & USE_I2C3_MODULE)
+    I2C3_NUM,
+#endif
+    I2C_NUM_I2C,
+};
+
+/* Module interface map structure */
+struct i2c_map
+{
+    volatile uint16_t iadr;    /* 0x00 */
+    volatile uint16_t unused1;
+    volatile uint16_t ifdr;    /* 0x04 */
+    volatile uint16_t unused2;
+    volatile uint16_t i2cr;    /* 0x08 */
+    volatile uint16_t unused3;
+    volatile uint16_t i2sr;    /* 0x0C */
+    volatile uint16_t unused4;
+    volatile uint16_t i2dr;    /* 0x10 */
+};
+
+struct i2c_node
+{
+    enum i2c_module_number num; /* Module that this node uses */
+    unsigned int ifdr;          /* Maximum frequency for node */
+    unsigned char addr;         /* Slave address on module */
+};
 
 void i2c_init(void);
-void i2c_write(int addr, const unsigned char *data, int count);
+/* Enable or disable the node - modules will be switch on/off accordingly. */
+void i2c_enable_node(struct i2c_node *node, bool enable);
+/* If addr < 0, then raw read */
+int i2c_read(struct i2c_node *node, int addr, unsigned char *data, int count);
+int i2c_write(struct i2c_node *node, const unsigned char *data, int count);
+/* Gain mutually-exclusive access to the node and module to perform multiple
+ * operations atomically */
+void i2c_lock_node(struct i2c_node *node);
+void i2c_unlock_node(struct i2c_node *node);
 
+#endif /* _I2C_IMX31_H_ */
diff --git a/firmware/target/arm/imx31/gigabeat-s/pcm-imx31.c b/firmware/target/arm/imx31/gigabeat-s/pcm-imx31.c
index 4d2206b..e37f6bf 100644
--- a/firmware/target/arm/imx31/gigabeat-s/pcm-imx31.c
+++ b/firmware/target/arm/imx31/gigabeat-s/pcm-imx31.c
@@ -49,10 +49,12 @@ void pcm_apply_settings(void)
 
 void pcm_play_dma_init(void)
 {
+    audiohw_init();
 }
 
 void pcm_postinit(void)
 {
+    audiohw_postinit();
 }
 
 #if 0
diff --git a/firmware/target/arm/imx31/gigabeat-s/wmcodec-imx31.c b/firmware/target/arm/imx31/gigabeat-s/wmcodec-imx31.c
index 238ee3a..235ae54 100644
--- a/firmware/target/arm/imx31/gigabeat-s/wmcodec-imx31.c
+++ b/firmware/target/arm/imx31/gigabeat-s/wmcodec-imx31.c
@@ -7,7 +7,7 @@
  *                     \/            \/     \/    \/            \/
  * $Id$
  *
- * Gigabeat specific code for the Wolfson codec
+ * Gigabeat  S specific code for the WM8978 codec
  *
  * Based on code from the ipodlinux project - http://ipodlinux.org/
  * Adapted for Rockbox in December 2005
@@ -28,12 +28,31 @@
 #include "sound.h"
 #include "i2c-imx31.h"
 
+/* NOTE: Some port-specific bits will have to be moved away (node and GPIO
+ * writes) for cleanest implementation. */
+
+static struct i2c_node wm8978_i2c_node =
+{
+    .num  = I2C1_NUM,
+    .ifdr = I2C_IFDR_DIV192, /* 66MHz/.4MHz = 165, closest = 192 = 343750Hz */
+                             /* Just hard-code for now - scaling may require 
+                              * updating */
+    .addr = WM8978_I2C_ADDR,
+};
+
 void audiohw_init(void)
 {
+    i2c_enable_node(&wm8978_i2c_node, true);
+    GPIO3_DR |= (1 << 21); /* Turn on analogue LDO */
+    sleep(HZ/10);          /* Wait for things to stabilize */
+    audiohw_preinit();
 }
 
 void wmcodec_write(int reg, int data)
 {
-    (void)reg;
-    (void)data;
+    unsigned char d[2];
+    /* |aaaaaaad|dddddddd| */
+    d[0] = (reg << 1) | ((data & 0x100) >> 8);
+    d[1] = data;
+    i2c_write(&wm8978_i2c_node, d, 2);
 }