ASoC: add a WM8978 codec driver

The WM8978 codec from Wolfson Microelectronics is very similar to
wm8974, but is stereo and also has some differences in pin configuration
and internal signal routing. This driver is based on wm8974 and takes
the differences into account.

Signed-off-by: Guennadi Liakhovetski <g.liakhovetski@gmx.de>
Acked-by: Liam Girdwood <lrg@slimlogic.co.uk>
Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com>

1 files changed, 1124 insertions, 0 deletions

diff --git a/sound/soc/codecs/wm8978.c b/sound/soc/codecs/wm8978.c
new file mode 100644
index 000000000000..d9d4e9dd1adb
--- /dev/null
+++ b/sound/soc/codecs/wm8978.c
@@ -0,0 +1,1124 @@
+/*
+ * wm8978.c  --  WM8978 ALSA SoC Audio Codec driver
+ *
+ * Copyright (C) 2009-2010 Guennadi Liakhovetski <g.liakhovetski@gmx.de>
+ * Copyright (C) 2007 Carlos Munoz <carlos@kenati.com>
+ * Copyright 2006-2009 Wolfson Microelectronics PLC.
+ * Based on wm8974 and wm8990 by Liam Girdwood <lrg@slimlogic.co.uk>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ */
+
+#include <linux/module.h>
+#include <linux/moduleparam.h>
+#include <linux/kernel.h>
+#include <linux/init.h>
+#include <linux/delay.h>
+#include <linux/pm.h>
+#include <linux/i2c.h>
+#include <linux/platform_device.h>
+#include <sound/core.h>
+#include <sound/pcm.h>
+#include <sound/pcm_params.h>
+#include <sound/soc.h>
+#include <sound/soc-dapm.h>
+#include <sound/initval.h>
+#include <sound/tlv.h>
+#include <asm/div64.h>
+
+#include "wm8978.h"
+
+static struct snd_soc_codec *wm8978_codec;
+
+/* wm8978 register cache. Note that register 0 is not included in the cache. */
+static const u16 wm8978_reg[WM8978_CACHEREGNUM] = {
+	0x0000, 0x0000, 0x0000, 0x0000,	/* 0x00...0x03 */
+	0x0050, 0x0000, 0x0140, 0x0000,	/* 0x04...0x07 */
+	0x0000, 0x0000, 0x0000, 0x00ff,	/* 0x08...0x0b */
+	0x00ff, 0x0000, 0x0100, 0x00ff,	/* 0x0c...0x0f */
+	0x00ff, 0x0000, 0x012c, 0x002c,	/* 0x10...0x13 */
+	0x002c, 0x002c, 0x002c, 0x0000,	/* 0x14...0x17 */
+	0x0032, 0x0000, 0x0000, 0x0000,	/* 0x18...0x1b */
+	0x0000, 0x0000, 0x0000, 0x0000,	/* 0x1c...0x1f */
+	0x0038, 0x000b, 0x0032, 0x0000,	/* 0x20...0x23 */
+	0x0008, 0x000c, 0x0093, 0x00e9,	/* 0x24...0x27 */
+	0x0000, 0x0000, 0x0000, 0x0000,	/* 0x28...0x2b */
+	0x0033, 0x0010, 0x0010, 0x0100,	/* 0x2c...0x2f */
+	0x0100, 0x0002, 0x0001, 0x0001,	/* 0x30...0x33 */
+	0x0039, 0x0039, 0x0039, 0x0039,	/* 0x34...0x37 */
+	0x0001,	0x0001,			/* 0x38...0x3b */
+};
+
+/* codec private data */
+struct wm8978_priv {
+	struct snd_soc_codec codec;
+	unsigned int f_pllout;
+	unsigned int f_mclk;
+	unsigned int f_256fs;
+	unsigned int f_opclk;
+	enum wm8978_sysclk_src sysclk;
+	u16 reg_cache[WM8978_CACHEREGNUM];
+};
+
+static const char *wm8978_companding[] = {"Off", "NC", "u-law", "A-law"};
+static const char *wm8978_eqmode[] = {"Capture", "Playback"};
+static const char *wm8978_bw[] = {"Narrow", "Wide"};
+static const char *wm8978_eq1[] = {"80Hz", "105Hz", "135Hz", "175Hz"};
+static const char *wm8978_eq2[] = {"230Hz", "300Hz", "385Hz", "500Hz"};
+static const char *wm8978_eq3[] = {"650Hz", "850Hz", "1.1kHz", "1.4kHz"};
+static const char *wm8978_eq4[] = {"1.8kHz", "2.4kHz", "3.2kHz", "4.1kHz"};
+static const char *wm8978_eq5[] = {"5.3kHz", "6.9kHz", "9kHz", "11.7kHz"};
+static const char *wm8978_alc3[] = {"ALC", "Limiter"};
+static const char *wm8978_alc1[] = {"Off", "Right", "Left", "Both"};
+
+static const SOC_ENUM_SINGLE_DECL(adc_compand, WM8978_COMPANDING_CONTROL, 1,
+				  wm8978_companding);
+static const SOC_ENUM_SINGLE_DECL(dac_compand, WM8978_COMPANDING_CONTROL, 3,
+				  wm8978_companding);
+static const SOC_ENUM_SINGLE_DECL(eqmode, WM8978_EQ1, 8, wm8978_eqmode);
+static const SOC_ENUM_SINGLE_DECL(eq1, WM8978_EQ1, 5, wm8978_eq1);
+static const SOC_ENUM_SINGLE_DECL(eq2bw, WM8978_EQ2, 8, wm8978_bw);
+static const SOC_ENUM_SINGLE_DECL(eq2, WM8978_EQ2, 5, wm8978_eq2);
+static const SOC_ENUM_SINGLE_DECL(eq3bw, WM8978_EQ3, 8, wm8978_bw);
+static const SOC_ENUM_SINGLE_DECL(eq3, WM8978_EQ3, 5, wm8978_eq3);
+static const SOC_ENUM_SINGLE_DECL(eq4bw, WM8978_EQ4, 8, wm8978_bw);
+static const SOC_ENUM_SINGLE_DECL(eq4, WM8978_EQ4, 5, wm8978_eq4);
+static const SOC_ENUM_SINGLE_DECL(eq5, WM8978_EQ5, 5, wm8978_eq5);
+static const SOC_ENUM_SINGLE_DECL(alc3, WM8978_ALC_CONTROL_3, 8, wm8978_alc3);
+static const SOC_ENUM_SINGLE_DECL(alc1, WM8978_ALC_CONTROL_1, 7, wm8978_alc1);
+
+static const DECLARE_TLV_DB_SCALE(digital_tlv, -12750, 50, 1);
+static const DECLARE_TLV_DB_SCALE(eq_tlv, -1200, 100, 0);
+static const DECLARE_TLV_DB_SCALE(inpga_tlv, -1200, 75, 0);
+static const DECLARE_TLV_DB_SCALE(spk_tlv, -5700, 100, 0);
+static const DECLARE_TLV_DB_SCALE(boost_tlv, -1500, 300, 1);
+
+static const struct snd_kcontrol_new wm8978_snd_controls[] = {
+
+	SOC_SINGLE("Digital Loopback Switch",
+		WM8978_COMPANDING_CONTROL, 0, 1, 0),
+
+	SOC_ENUM("ADC Companding", adc_compand),
+	SOC_ENUM("DAC Companding", dac_compand),
+
+	SOC_DOUBLE("DAC Inversion Switch", WM8978_DAC_CONTROL, 0, 1, 1, 0),
+
+	SOC_DOUBLE_R_TLV("PCM Volume",
+		WM8978_LEFT_DAC_DIGITAL_VOLUME, WM8978_RIGHT_DAC_DIGITAL_VOLUME,
+		0, 255, 0, digital_tlv),
+
+	SOC_SINGLE("High Pass Filter Switch", WM8978_ADC_CONTROL, 8, 1, 0),
+	SOC_SINGLE("High Pass Cut Off", WM8978_ADC_CONTROL, 4, 7, 0),
+	SOC_DOUBLE("ADC Inversion Switch", WM8978_ADC_CONTROL, 0, 1, 1, 0),
+
+	SOC_DOUBLE_R_TLV("ADC Volume",
+		WM8978_LEFT_ADC_DIGITAL_VOLUME, WM8978_RIGHT_ADC_DIGITAL_VOLUME,
+		0, 255, 0, digital_tlv),
+
+	SOC_ENUM("Equaliser Function", eqmode),
+	SOC_ENUM("EQ1 Cut Off", eq1),
+	SOC_SINGLE_TLV("EQ1 Volume", WM8978_EQ1,  0, 24, 1, eq_tlv),
+
+	SOC_ENUM("Equaliser EQ2 Bandwith", eq2bw),
+	SOC_ENUM("EQ2 Cut Off", eq2),
+	SOC_SINGLE_TLV("EQ2 Volume", WM8978_EQ2,  0, 24, 1, eq_tlv),
+
+	SOC_ENUM("Equaliser EQ3 Bandwith", eq3bw),
+	SOC_ENUM("EQ3 Cut Off", eq3),
+	SOC_SINGLE_TLV("EQ3 Volume", WM8978_EQ3,  0, 24, 1, eq_tlv),
+
+	SOC_ENUM("Equaliser EQ4 Bandwith", eq4bw),
+	SOC_ENUM("EQ4 Cut Off", eq4),
+	SOC_SINGLE_TLV("EQ4 Volume", WM8978_EQ4,  0, 24, 1, eq_tlv),
+
+	SOC_ENUM("EQ5 Cut Off", eq5),
+	SOC_SINGLE_TLV("EQ5 Volume", WM8978_EQ5, 0, 24, 1, eq_tlv),
+
+	SOC_SINGLE("DAC Playback Limiter Switch",
+		WM8978_DAC_LIMITER_1, 8, 1, 0),
+	SOC_SINGLE("DAC Playback Limiter Decay",
+		WM8978_DAC_LIMITER_1, 4, 15, 0),
+	SOC_SINGLE("DAC Playback Limiter Attack",
+		WM8978_DAC_LIMITER_1, 0, 15, 0),
+
+	SOC_SINGLE("DAC Playback Limiter Threshold",
+		WM8978_DAC_LIMITER_2, 4, 7, 0),
+	SOC_SINGLE("DAC Playback Limiter Boost",
+		WM8978_DAC_LIMITER_2, 0, 15, 0),
+
+	SOC_ENUM("ALC Enable Switch", alc1),
+	SOC_SINGLE("ALC Capture Min Gain", WM8978_ALC_CONTROL_1, 0, 7, 0),
+	SOC_SINGLE("ALC Capture Max Gain", WM8978_ALC_CONTROL_1, 3, 7, 0),
+
+	SOC_SINGLE("ALC Capture Hold", WM8978_ALC_CONTROL_2, 4, 7, 0),
+	SOC_SINGLE("ALC Capture Target", WM8978_ALC_CONTROL_2, 0, 15, 0),
+
+	SOC_ENUM("ALC Capture Mode", alc3),
+	SOC_SINGLE("ALC Capture Decay", WM8978_ALC_CONTROL_3, 4, 15, 0),
+	SOC_SINGLE("ALC Capture Attack", WM8978_ALC_CONTROL_3, 0, 15, 0),
+
+	SOC_SINGLE("ALC Capture Noise Gate Switch", WM8978_NOISE_GATE, 3, 1, 0),
+	SOC_SINGLE("ALC Capture Noise Gate Threshold",
+		WM8978_NOISE_GATE, 0, 7, 0),
+
+	SOC_DOUBLE_R("Capture PGA ZC Switch",
+		WM8978_LEFT_INP_PGA_CONTROL, WM8978_RIGHT_INP_PGA_CONTROL,
+		7, 1, 0),
+
+	/* OUT1 - Headphones */
+	SOC_DOUBLE_R("Headphone Playback ZC Switch",
+		WM8978_LOUT1_HP_CONTROL, WM8978_ROUT1_HP_CONTROL, 7, 1, 0),
+
+	SOC_DOUBLE_R_TLV("Headphone Playback Volume",
+		WM8978_LOUT1_HP_CONTROL, WM8978_ROUT1_HP_CONTROL,
+		0, 63, 0, spk_tlv),
+
+	/* OUT2 - Speakers */
+	SOC_DOUBLE_R("Speaker Playback ZC Switch",
+		WM8978_LOUT2_SPK_CONTROL, WM8978_ROUT2_SPK_CONTROL, 7, 1, 0),
+
+	SOC_DOUBLE_R_TLV("Speaker Playback Volume",
+		WM8978_LOUT2_SPK_CONTROL, WM8978_ROUT2_SPK_CONTROL,
+		0, 63, 0, spk_tlv),
+
+	/* OUT3/4 - Line Output */
+	SOC_DOUBLE_R("Line Playback Switch",
+		WM8978_OUT3_MIXER_CONTROL, WM8978_OUT4_MIXER_CONTROL, 6, 1, 1),
+
+	/* Mixer #3: Boost (Input) mixer */
+	SOC_DOUBLE_R("PGA Boost (+20dB)",
+		WM8978_LEFT_ADC_BOOST_CONTROL, WM8978_RIGHT_ADC_BOOST_CONTROL,
+		8, 1, 0),
+	SOC_DOUBLE_R_TLV("L2/R2 Boost Volume",
+		WM8978_LEFT_ADC_BOOST_CONTROL, WM8978_RIGHT_ADC_BOOST_CONTROL,
+		4, 7, 0, boost_tlv),
+	SOC_DOUBLE_R_TLV("Aux Boost Volume",
+		WM8978_LEFT_ADC_BOOST_CONTROL, WM8978_RIGHT_ADC_BOOST_CONTROL,
+		0, 7, 0, boost_tlv),
+
+	/* Input PGA volume */
+	SOC_DOUBLE_R_TLV("Input PGA Volume",
+		WM8978_LEFT_INP_PGA_CONTROL, WM8978_RIGHT_INP_PGA_CONTROL,
+		0, 63, 0, inpga_tlv),
+
+	/* Headphone */
+	SOC_DOUBLE_R("Headphone Switch",
+		WM8978_LOUT1_HP_CONTROL, WM8978_ROUT1_HP_CONTROL, 6, 1, 1),
+
+	/* Speaker */
+	SOC_DOUBLE_R("Speaker Switch",
+		WM8978_LOUT2_SPK_CONTROL, WM8978_ROUT2_SPK_CONTROL, 6, 1, 1),
+};
+
+/* Mixer #1: Output (OUT1, OUT2) Mixer: mix AUX, Input mixer output and DAC */
+static const struct snd_kcontrol_new wm8978_left_out_mixer[] = {
+	SOC_DAPM_SINGLE("Line Bypass Switch", WM8978_LEFT_MIXER_CONTROL, 1, 1, 0),
+	SOC_DAPM_SINGLE("Aux Playback Switch", WM8978_LEFT_MIXER_CONTROL, 5, 1, 0),
+	SOC_DAPM_SINGLE("PCM Playback Switch", WM8978_LEFT_MIXER_CONTROL, 0, 1, 0),
+};
+
+static const struct snd_kcontrol_new wm8978_right_out_mixer[] = {
+	SOC_DAPM_SINGLE("Line Bypass Switch", WM8978_RIGHT_MIXER_CONTROL, 1, 1, 0),
+	SOC_DAPM_SINGLE("Aux Playback Switch", WM8978_RIGHT_MIXER_CONTROL, 5, 1, 0),
+	SOC_DAPM_SINGLE("PCM Playback Switch", WM8978_RIGHT_MIXER_CONTROL, 0, 1, 0),
+};
+
+/* OUT3/OUT4 Mixer not implemented */
+
+/* Mixer #2: Input PGA Mute */
+static const struct snd_kcontrol_new wm8978_left_input_mixer[] = {
+	SOC_DAPM_SINGLE("L2 Switch", WM8978_INPUT_CONTROL, 2, 1, 0),
+	SOC_DAPM_SINGLE("MicN Switch", WM8978_INPUT_CONTROL, 1, 1, 0),
+	SOC_DAPM_SINGLE("MicP Switch", WM8978_INPUT_CONTROL, 0, 1, 0),
+};
+static const struct snd_kcontrol_new wm8978_right_input_mixer[] = {
+	SOC_DAPM_SINGLE("R2 Switch", WM8978_INPUT_CONTROL, 6, 1, 0),
+	SOC_DAPM_SINGLE("MicN Switch", WM8978_INPUT_CONTROL, 5, 1, 0),
+	SOC_DAPM_SINGLE("MicP Switch", WM8978_INPUT_CONTROL, 4, 1, 0),
+};
+
+static const struct snd_soc_dapm_widget wm8978_dapm_widgets[] = {
+	SND_SOC_DAPM_DAC("Left DAC", "Left HiFi Playback",
+			 WM8978_POWER_MANAGEMENT_3, 0, 0),
+	SND_SOC_DAPM_DAC("Right DAC", "Right HiFi Playback",
+			 WM8978_POWER_MANAGEMENT_3, 1, 0),
+	SND_SOC_DAPM_ADC("Left ADC", "Left HiFi Capture",
+			 WM8978_POWER_MANAGEMENT_2, 0, 0),
+	SND_SOC_DAPM_ADC("Right ADC", "Right HiFi Capture",
+			 WM8978_POWER_MANAGEMENT_2, 1, 0),
+
+	/* Mixer #1: OUT1,2 */
+	SOC_MIXER_ARRAY("Left Output Mixer", WM8978_POWER_MANAGEMENT_3,
+			2, 0, wm8978_left_out_mixer),
+	SOC_MIXER_ARRAY("Right Output Mixer", WM8978_POWER_MANAGEMENT_3,
+			3, 0, wm8978_right_out_mixer),
+
+	SOC_MIXER_ARRAY("Left Input Mixer", WM8978_POWER_MANAGEMENT_2,
+			2, 0, wm8978_left_input_mixer),
+	SOC_MIXER_ARRAY("Right Input Mixer", WM8978_POWER_MANAGEMENT_2,
+			3, 0, wm8978_right_input_mixer),
+
+	SND_SOC_DAPM_PGA("Left Boost Mixer", WM8978_POWER_MANAGEMENT_2,
+			 4, 0, NULL, 0),
+	SND_SOC_DAPM_PGA("Right Boost Mixer", WM8978_POWER_MANAGEMENT_2,
+			 5, 0, NULL, 0),
+
+	SND_SOC_DAPM_PGA("Left Capture PGA", WM8978_LEFT_INP_PGA_CONTROL,
+			 6, 1, NULL, 0),
+	SND_SOC_DAPM_PGA("Right Capture PGA", WM8978_RIGHT_INP_PGA_CONTROL,
+			 6, 1, NULL, 0),
+
+	SND_SOC_DAPM_PGA("Left Headphone Out", WM8978_POWER_MANAGEMENT_2,
+			 7, 0, NULL, 0),
+	SND_SOC_DAPM_PGA("Right Headphone Out", WM8978_POWER_MANAGEMENT_2,
+			 8, 0, NULL, 0),
+
+	SND_SOC_DAPM_PGA("Left Speaker Out", WM8978_POWER_MANAGEMENT_3,
+			 6, 0, NULL, 0),
+	SND_SOC_DAPM_PGA("Right Speaker Out", WM8978_POWER_MANAGEMENT_3,
+			 5, 0, NULL, 0),
+
+	SND_SOC_DAPM_MIXER("OUT4 VMID", WM8978_POWER_MANAGEMENT_3,
+			   8, 0, NULL, 0),
+
+	SND_SOC_DAPM_MICBIAS("Mic Bias", WM8978_POWER_MANAGEMENT_1, 4, 0),
+
+	SND_SOC_DAPM_INPUT("LMICN"),
+	SND_SOC_DAPM_INPUT("LMICP"),
+	SND_SOC_DAPM_INPUT("RMICN"),
+	SND_SOC_DAPM_INPUT("RMICP"),
+	SND_SOC_DAPM_INPUT("LAUX"),
+	SND_SOC_DAPM_INPUT("RAUX"),
+	SND_SOC_DAPM_INPUT("L2"),
+	SND_SOC_DAPM_INPUT("R2"),
+	SND_SOC_DAPM_OUTPUT("LHP"),
+	SND_SOC_DAPM_OUTPUT("RHP"),
+	SND_SOC_DAPM_OUTPUT("LSPK"),
+	SND_SOC_DAPM_OUTPUT("RSPK"),
+};
+
+static const struct snd_soc_dapm_route audio_map[] = {
+	/* Output mixer */
+	{"Right Output Mixer", "PCM Playback Switch", "Right DAC"},
+	{"Right Output Mixer", "Aux Playback Switch", "RAUX"},
+	{"Right Output Mixer", "Line Bypass Switch", "Right Boost Mixer"},
+
+	{"Left Output Mixer", "PCM Playback Switch", "Left DAC"},
+	{"Left Output Mixer", "Aux Playback Switch", "LAUX"},
+	{"Left Output Mixer", "Line Bypass Switch", "Left Boost Mixer"},
+
+	/* Outputs */
+	{"Right Headphone Out", NULL, "Right Output Mixer"},
+	{"RHP", NULL, "Right Headphone Out"},
+
+	{"Left Headphone Out", NULL, "Left Output Mixer"},
+	{"LHP", NULL, "Left Headphone Out"},
+
+	{"Right Speaker Out", NULL, "Right Output Mixer"},
+	{"RSPK", NULL, "Right Speaker Out"},
+
+	{"Left Speaker Out", NULL, "Left Output Mixer"},
+	{"LSPK", NULL, "Left Speaker Out"},
+
+	/* Boost Mixer */
+	{"Right ADC", NULL, "Right Boost Mixer"},
+
+	{"Right Boost Mixer", NULL, "RAUX"},
+	{"Right Boost Mixer", NULL, "Right Capture PGA"},
+	{"Right Boost Mixer", NULL, "R2"},
+
+	{"Left ADC", NULL, "Left Boost Mixer"},
+
+	{"Left Boost Mixer", NULL, "LAUX"},
+	{"Left Boost Mixer", NULL, "Left Capture PGA"},
+	{"Left Boost Mixer", NULL, "L2"},
+
+	/* Input PGA */
+	{"Right Capture PGA", NULL, "Right Input Mixer"},
+	{"Left Capture PGA", NULL, "Left Input Mixer"},
+
+	{"Right Input Mixer", "R2 Switch", "R2"},
+	{"Right Input Mixer", "MicN Switch", "RMICN"},
+	{"Right Input Mixer", "MicP Switch", "RMICP"},
+
+	{"Left Input Mixer", "L2 Switch", "L2"},
+	{"Left Input Mixer", "MicN Switch", "LMICN"},
+	{"Left Input Mixer", "MicP Switch", "LMICP"},
+};
+
+static int wm8978_add_widgets(struct snd_soc_codec *codec)
+{
+	snd_soc_dapm_new_controls(codec, wm8978_dapm_widgets,
+				  ARRAY_SIZE(wm8978_dapm_widgets));
+
+	/* set up the WM8978 audio map */
+	snd_soc_dapm_add_routes(codec, audio_map, ARRAY_SIZE(audio_map));
+
+	return 0;
+}
+
+/* PLL divisors */
+struct wm8978_pll_div {
+	u32 k;
+	u8 n;
+	u8 div2;
+};
+
+#define FIXED_PLL_SIZE (1 << 24)
+
+static void pll_factors(struct wm8978_pll_div *pll_div, unsigned int target,
+			unsigned int source)
+{
+	u64 k_part;
+	unsigned int k, n_div, n_mod;
+
+	n_div = target / source;
+	if (n_div < 6) {
+		source >>= 1;
+		pll_div->div2 = 1;
+		n_div = target / source;
+	} else {
+		pll_div->div2 = 0;
+	}
+
+	if (n_div < 6 || n_div > 12)
+		dev_warn(wm8978_codec->dev,
+			 "WM8978 N value exceeds recommended range! N = %u\n",
+			 n_div);
+
+	pll_div->n = n_div;
+	n_mod = target - source * n_div;
+	k_part = FIXED_PLL_SIZE * (long long)n_mod + source / 2;
+
+	do_div(k_part, source);
+
+	k = k_part & 0xFFFFFFFF;
+
+	pll_div->k = k;
+}
+/*
+ * Calculate internal frequencies and dividers, according to Figure 40
+ * "PLL and Clock Select Circuit" in WM8978 datasheet Rev. 2.6
+ */
+static int wm8978_configure_pll(struct snd_soc_codec *codec)
+{
+	struct wm8978_priv *wm8978 = codec->private_data;
+	struct wm8978_pll_div pll_div;
+	unsigned int f_opclk = wm8978->f_opclk, f_mclk = wm8978->f_mclk,
+		f_256fs = wm8978->f_256fs;
+	unsigned int f2, opclk_div;
+
+	if (!f_mclk)
+		return -EINVAL;
+
+	if (f_opclk) {
+		/*
+		 * The user needs OPCLK. Choose OPCLKDIV to put
+		 * 6 <= R = f2 / f1 < 13, 1 <= OPCLKDIV <= 4.
+		 * f_opclk = f_mclk * prescale * R / 4 / OPCLKDIV, where
+		 * prescale = 1, or prescale = 2. Prescale is calculated inside
+		 * pll_factors(). We have to select f_PLLOUT, such that
+		 * f_mclk * 3 / 4 <= f_PLLOUT < f_mclk * 13 / 4. Must be
+		 * f_mclk * 3 / 16 <= f_opclk < f_mclk * 13 / 4.
+		 */
+		if (16 * f_opclk < 3 * f_mclk || 4 * f_opclk >= 13 * f_mclk)
+			return -EINVAL;
+
+		if (4 * f_opclk < 3 * f_mclk)
+			/* Have to use OPCLKDIV */
+			opclk_div = (3 * f_mclk / 4 + f_opclk - 1) / f_opclk;
+		else
+			opclk_div = 1;
+
+		dev_dbg(codec->dev, "%s: OPCLKDIV=%d\n", __func__, opclk_div);
+
+		snd_soc_update_bits(codec, WM8978_GPIO_CONTROL, 0x30,
+				    (opclk_div - 1) << 4);
+
+		wm8978->f_pllout = f_opclk * opclk_div;
+	} else if (f_256fs) {
+		/*
+		 * Not using OPCLK, choose R:
+		 * 6 <= R = f2 / f1 < 13, to put 1 <= MCLKDIV <= 12.
+		 * f_256fs = f_mclk * prescale * R / 4 / MCLKDIV, where
+		 * prescale = 1, or prescale = 2. Prescale is calculated inside
+		 * pll_factors(). We have to select f_PLLOUT, such that
+		 * f_mclk * 3 / 4 <= f_PLLOUT < f_mclk * 13 / 4. Must be
+		 * f_mclk * 3 / 48 <= f_256fs < f_mclk * 13 / 4. This means MCLK
+		 * must be 3.781MHz <= f_MCLK <= 32.768MHz
+		 */
+		if (48 * f_256fs < 3 * f_mclk || 4 * f_256fs >= 13 * f_mclk)
+			return -EINVAL;
+
+		/*
+		 * MCLKDIV will be selected in .hw_params(), just choose a
+		 * suitable f_PLLOUT
+		 */
+		if (4 * f_256fs < 3 * f_mclk)
+			/* Will have to use MCLKDIV */
+			wm8978->f_pllout = wm8978->f_mclk * 3 / 4;
+		else
+			wm8978->f_pllout = f_256fs;
+
+		/* GPIO1 into default mode as input - before configuring PLL */
+		snd_soc_update_bits(codec, WM8978_GPIO_CONTROL, 7, 0);
+	} else {
+		return -EINVAL;
+	}
+
+	f2 = wm8978->f_pllout * 4;
+
+	dev_dbg(codec->dev, "%s: f_MCLK=%uHz, f_PLLOUT=%uHz\n", __func__,
+		wm8978->f_mclk, wm8978->f_pllout);
+
+	pll_factors(&pll_div, f2, wm8978->f_mclk);
+
+	dev_dbg(codec->dev, "%s: calculated PLL N=0x%x, K=0x%x, div2=%d\n",
+		__func__, pll_div.n, pll_div.k, pll_div.div2);
+
+	/* Turn PLL off for configuration... */
+	snd_soc_update_bits(codec, WM8978_POWER_MANAGEMENT_1, 0x20, 0);
+
+	snd_soc_write(codec, WM8978_PLL_N, (pll_div.div2 << 4) | pll_div.n);
+	snd_soc_write(codec, WM8978_PLL_K1, pll_div.k >> 18);
+	snd_soc_write(codec, WM8978_PLL_K2, (pll_div.k >> 9) & 0x1ff);
+	snd_soc_write(codec, WM8978_PLL_K3, pll_div.k & 0x1ff);
+
+	/* ...and on again */
+	snd_soc_update_bits(codec, WM8978_POWER_MANAGEMENT_1, 0x20, 0x20);
+
+	if (f_opclk)
+		/* Output PLL (OPCLK) to GPIO1 */
+		snd_soc_update_bits(codec, WM8978_GPIO_CONTROL, 7, 4);
+
+	return 0;
+}
+
+/*
+ * Configure WM8978 clock dividers.
+ */
+static int wm8978_set_dai_clkdiv(struct snd_soc_dai *codec_dai,
+				 int div_id, int div)
+{
+	struct snd_soc_codec *codec = codec_dai->codec;
+	struct wm8978_priv *wm8978 = codec->private_data;
+	int ret = 0;
+
+	switch (div_id) {
+	case WM8978_OPCLKRATE:
+		wm8978->f_opclk = div;
+
+		if (wm8978->f_mclk)
+			ret = wm8978_configure_pll(codec);
+		break;
+	case WM8978_MCLKDIV:
+		if (div & ~0xe0)
+			return -EINVAL;
+		snd_soc_update_bits(codec, WM8978_CLOCKING, 0xe0, div);
+		break;
+	case WM8978_ADCCLK:
+		if (div & ~8)
+			return -EINVAL;
+		snd_soc_update_bits(codec, WM8978_ADC_CONTROL, 8, div);
+		break;
+	case WM8978_DACCLK:
+		if (div & ~8)
+			return -EINVAL;
+		snd_soc_update_bits(codec, WM8978_DAC_CONTROL, 8, div);
+		break;
+	case WM8978_BCLKDIV:
+		if (div & ~0x1c)
+			return -EINVAL;
+		snd_soc_update_bits(codec, WM8978_CLOCKING, 0x1c, div);
+		break;
+	default:
+		return -EINVAL;
+	}
+
+	dev_dbg(codec->dev, "%s: ID %d, value %u\n", __func__, div_id, div);
+
+	return ret;
+}
+
+/*
+ * @freq:	when .set_pll() us not used, freq is codec MCLK input frequency
+ */
+static int wm8978_set_dai_sysclk(struct snd_soc_dai *codec_dai, int clk_id,
+				 unsigned int freq, int dir)
+{
+	struct snd_soc_codec *codec = codec_dai->codec;
+	struct wm8978_priv *wm8978 = codec->private_data;
+	int ret = 0;
+
+	dev_dbg(codec->dev, "%s: ID %d, freq %u\n", __func__, clk_id, freq);
+
+	if (freq) {
+		wm8978->f_mclk = freq;
+
+		/* Even if MCLK is used for system clock, might have to drive OPCLK */
+		if (wm8978->f_opclk)
+			ret = wm8978_configure_pll(codec);
+
+		/* Our sysclk is fixed to 256 * fs, will configure in .hw_params()  */
+
+		if (!ret)
+			wm8978->sysclk = clk_id;
+	}
+
+	if (wm8978->sysclk == WM8978_PLL && (!freq || clk_id == WM8978_MCLK)) {
+		/* Clock CODEC directly from MCLK */
+		snd_soc_update_bits(codec, WM8978_CLOCKING, 0x100, 0);
+
+		/* GPIO1 into default mode as input - before configuring PLL */
+		snd_soc_update_bits(codec, WM8978_GPIO_CONTROL, 7, 0);
+
+		/* Turn off PLL */
+		snd_soc_update_bits(codec, WM8978_POWER_MANAGEMENT_1, 0x20, 0);
+		wm8978->sysclk = WM8978_MCLK;
+		wm8978->f_pllout = 0;
+		wm8978->f_opclk = 0;
+	}
+
+	return ret;
+}
+
+/*
+ * Set ADC and Voice DAC format.
+ */
+static int wm8978_set_dai_fmt(struct snd_soc_dai *codec_dai, unsigned int fmt)
+{
+	struct snd_soc_codec *codec = codec_dai->codec;
+	/*
+	 * BCLK polarity mask = 0x100, LRC clock polarity mask = 0x80,
+	 * Data Format mask = 0x18: all will be calculated anew
+	 */
+	u16 iface = snd_soc_read(codec, WM8978_AUDIO_INTERFACE) & ~0x198;
+	u16 clk = snd_soc_read(codec, WM8978_CLOCKING);
+
+	dev_dbg(codec->dev, "%s\n", __func__);
+
+	/* set master/slave audio interface */
+	switch (fmt & SND_SOC_DAIFMT_MASTER_MASK) {
+	case SND_SOC_DAIFMT_CBM_CFM:
+		clk |= 1;
+		break;
+	case SND_SOC_DAIFMT_CBS_CFS:
+		clk &= ~1;
+		break;
+	default:
+		return -EINVAL;
+	}
+
+	/* interface format */
+	switch (fmt & SND_SOC_DAIFMT_FORMAT_MASK) {
+	case SND_SOC_DAIFMT_I2S:
+		iface |= 0x10;
+		break;
+	case SND_SOC_DAIFMT_RIGHT_J:
+		break;
+	case SND_SOC_DAIFMT_LEFT_J:
+		iface |= 0x8;
+		break;
+	case SND_SOC_DAIFMT_DSP_A:
+		iface |= 0x18;
+		break;
+	default:
+		return -EINVAL;
+	}
+
+	/* clock inversion */
+	switch (fmt & SND_SOC_DAIFMT_INV_MASK) {
+	case SND_SOC_DAIFMT_NB_NF:
+		break;
+	case SND_SOC_DAIFMT_IB_IF:
+		iface |= 0x180;
+		break;
+	case SND_SOC_DAIFMT_IB_NF:
+		iface |= 0x100;
+		break;
+	case SND_SOC_DAIFMT_NB_IF:
+		iface |= 0x80;
+		break;
+	default:
+		return -EINVAL;
+	}
+
+	snd_soc_write(codec, WM8978_AUDIO_INTERFACE, iface);
+	snd_soc_write(codec, WM8978_CLOCKING, clk);
+
+	return 0;
+}
+
+/* MCLK dividers */
+static const int mclk_numerator[]	= {1, 3, 2, 3, 4, 6, 8, 12};
+static const int mclk_denominator[]	= {1, 2, 1, 1, 1, 1, 1, 1};
+
+/*
+ * Set PCM DAI bit size and sample rate.
+ */
+static int wm8978_hw_params(struct snd_pcm_substream *substream,
+			    struct snd_pcm_hw_params *params,
+			    struct snd_soc_dai *dai)
+{
+	struct snd_soc_pcm_runtime *rtd = substream->private_data;
+	struct snd_soc_device *socdev = rtd->socdev;
+	struct snd_soc_codec *codec = socdev->card->codec;
+	struct wm8978_priv *wm8978 = codec->private_data;
+	/* Word length mask = 0x60 */
+	u16 iface_ctl = snd_soc_read(codec, WM8978_AUDIO_INTERFACE) & ~0x60;
+	/* Sampling rate mask = 0xe (for filters) */
+	u16 add_ctl = snd_soc_read(codec, WM8978_ADDITIONAL_CONTROL) & ~0xe;
+	u16 clking = snd_soc_read(codec, WM8978_CLOCKING);
+	enum wm8978_sysclk_src current_clk_id = clking & 0x100 ?
+		WM8978_PLL : WM8978_MCLK;
+	unsigned int f_sel, diff, diff_best = INT_MAX;
+	int i, best = 0;
+
+	if (!wm8978->f_mclk)
+		return -EINVAL;
+
+	/* bit size */
+	switch (params_format(params)) {
+	case SNDRV_PCM_FORMAT_S16_LE:
+		break;
+	case SNDRV_PCM_FORMAT_S20_3LE:
+		iface_ctl |= 0x20;
+		break;
+	case SNDRV_PCM_FORMAT_S24_LE:
+		iface_ctl |= 0x40;
+		break;
+	case SNDRV_PCM_FORMAT_S32_LE:
+		iface_ctl |= 0x60;
+		break;
+	}
+
+	/* filter coefficient */
+	switch (params_rate(params)) {
+	case 8000:
+		add_ctl |= 0x5 << 1;
+		break;
+	case 11025:
+		add_ctl |= 0x4 << 1;
+		break;
+	case 16000:
+		add_ctl |= 0x3 << 1;
+		break;
+	case 22050:
+		add_ctl |= 0x2 << 1;
+		break;
+	case 32000:
+		add_ctl |= 0x1 << 1;
+		break;
+	case 44100:
+	case 48000:
+		break;
+	}
+
+	/* Sampling rate is known now, can configure the MCLK divider */
+	wm8978->f_256fs = params_rate(params) * 256;
+
+	if (wm8978->sysclk == WM8978_MCLK) {
+		f_sel = wm8978->f_mclk;
+	} else {
+		if (!wm8978->f_pllout) {
+			int ret = wm8978_configure_pll(codec);
+			if (ret < 0)
+				return ret;
+		}
+		f_sel = wm8978->f_pllout;
+	}
+
+	/*
+	 * In some cases it is possible to reconfigure PLL to a higher frequency
+	 * by raising OPCLKDIV, but normally OPCLK is configured to 256 * fs or
+	 * 512 * fs, so, we should be fine.
+	 */
+	if (f_sel < wm8978->f_256fs || f_sel > 12 * wm8978->f_256fs)
+		return -EINVAL;
+
+	for (i = 0; i < ARRAY_SIZE(mclk_numerator); i++) {
+		diff = abs(wm8978->f_256fs * 3 -
+			   f_sel * 3 * mclk_denominator[i] / mclk_numerator[i]);
+
+		if (diff < diff_best) {
+			diff_best = diff;
+			best = i;
+		}
+
+		if (!diff)
+			break;
+	}
+
+	if (diff)
+		dev_warn(codec->dev, "Imprecise clock: %u%s\n",
+			 f_sel * mclk_denominator[best] / mclk_numerator[best],
+			 wm8978->sysclk == WM8978_MCLK ?
+			 ", consider using PLL" : "");
+
+	dev_dbg(codec->dev, "%s: fmt %d, rate %u, MCLK divisor #%d\n", __func__,
+		params_format(params), params_rate(params), best);
+
+	/* MCLK divisor mask = 0xe0 */
+	snd_soc_update_bits(codec, WM8978_CLOCKING, 0xe0, best << 5);
+
+	snd_soc_write(codec, WM8978_AUDIO_INTERFACE, iface_ctl);
+	snd_soc_write(codec, WM8978_ADDITIONAL_CONTROL, add_ctl);
+
+	if (wm8978->sysclk != current_clk_id) {
+		if (wm8978->sysclk == WM8978_PLL)
+			/* Run CODEC from PLL instead of MCLK */
+			snd_soc_update_bits(codec, WM8978_CLOCKING,
+					    0x100, 0x100);
+		else
+			/* Clock CODEC directly from MCLK */
+			snd_soc_update_bits(codec, WM8978_CLOCKING, 0x100, 0);
+	}
+
+	return 0;
+}
+
+static int wm8978_mute(struct snd_soc_dai *dai, int mute)
+{
+	struct snd_soc_codec *codec = dai->codec;
+
+	dev_dbg(codec->dev, "%s: %d\n", __func__, mute);
+
+	if (mute)
+		snd_soc_update_bits(codec, WM8978_DAC_CONTROL, 0x40, 0x40);
+	else
+		snd_soc_update_bits(codec, WM8978_DAC_CONTROL, 0x40, 0);
+
+	return 0;
+}
+
+static int wm8978_set_bias_level(struct snd_soc_codec *codec,
+				 enum snd_soc_bias_level level)
+{
+	u16 power1 = snd_soc_read(codec, WM8978_POWER_MANAGEMENT_1) & ~3;
+
+	switch (level) {
+	case SND_SOC_BIAS_ON:
+	case SND_SOC_BIAS_PREPARE:
+		power1 |= 1;  /* VMID 75k */
+		snd_soc_write(codec, WM8978_POWER_MANAGEMENT_1, power1);
+		break;
+	case SND_SOC_BIAS_STANDBY:
+		/* bit 3: enable bias, bit 2: enable I/O tie off buffer */
+		power1 |= 0xc;
+
+		if (codec->bias_level == SND_SOC_BIAS_OFF) {
+			/* Initial cap charge at VMID 5k */
+			snd_soc_write(codec, WM8978_POWER_MANAGEMENT_1,
+				      power1 | 0x3);
+			mdelay(100);
+		}
+
+		power1 |= 0x2;  /* VMID 500k */
+		snd_soc_write(codec, WM8978_POWER_MANAGEMENT_1, power1);
+		break;
+	case SND_SOC_BIAS_OFF:
+		/* Preserve PLL - OPCLK may be used by someone */
+		snd_soc_update_bits(codec, WM8978_POWER_MANAGEMENT_1, ~0x20, 0);
+		snd_soc_write(codec, WM8978_POWER_MANAGEMENT_2, 0);
+		snd_soc_write(codec, WM8978_POWER_MANAGEMENT_3, 0);
+		break;
+	}
+
+	dev_dbg(codec->dev, "%s: %d, %x\n", __func__, level, power1);
+
+	codec->bias_level = level;
+	return 0;
+}
+
+#define WM8978_FORMATS (SNDRV_PCM_FMTBIT_S16_LE | SNDRV_PCM_FMTBIT_S20_3LE | \
+	SNDRV_PCM_FMTBIT_S24_LE | SNDRV_PCM_FMTBIT_S32_LE)
+
+static struct snd_soc_dai_ops wm8978_dai_ops = {
+	.hw_params	= wm8978_hw_params,
+	.digital_mute	= wm8978_mute,
+	.set_fmt	= wm8978_set_dai_fmt,
+	.set_clkdiv	= wm8978_set_dai_clkdiv,
+	.set_sysclk	= wm8978_set_dai_sysclk,
+};
+
+/* Also supports 12kHz */
+struct snd_soc_dai wm8978_dai = {
+	.name = "WM8978 HiFi",
+	.id = 1,
+	.playback = {
+		.stream_name = "Playback",
+		.channels_min = 1,
+		.channels_max = 2,
+		.rates = SNDRV_PCM_RATE_8000_48000,
+		.formats = WM8978_FORMATS,
+	},
+	.capture = {
+		.stream_name = "Capture",
+		.channels_min = 1,
+		.channels_max = 2,
+		.rates = SNDRV_PCM_RATE_8000_48000,
+		.formats = WM8978_FORMATS,
+	},
+	.ops = &wm8978_dai_ops,
+};
+EXPORT_SYMBOL_GPL(wm8978_dai);
+
+static int wm8978_suspend(struct platform_device *pdev, pm_message_t state)
+{
+	struct snd_soc_device *socdev = platform_get_drvdata(pdev);
+	struct snd_soc_codec *codec = socdev->card->codec;
+
+	wm8978_set_bias_level(codec, SND_SOC_BIAS_OFF);
+	/* Also switch PLL off */
+	snd_soc_write(codec, WM8978_POWER_MANAGEMENT_1, 0);
+	/* Put to sleep */
+	snd_soc_write(codec, WM8978_POWER_MANAGEMENT_2, 0x40);
+
+	return 0;
+}
+
+static int wm8978_resume(struct platform_device *pdev)
+{
+	struct snd_soc_device *socdev = platform_get_drvdata(pdev);
+	struct snd_soc_codec *codec = socdev->card->codec;
+	struct wm8978_priv *wm8978 = codec->private_data;
+	int i;
+	u16 *cache = codec->reg_cache;
+
+	/* Wake up the codec */
+	snd_soc_write(codec, WM8978_POWER_MANAGEMENT_2, 0);
+
+	/* Sync reg_cache with the hardware */
+	for (i = 0; i < ARRAY_SIZE(wm8978_reg); i++) {
+		if (i == WM8978_RESET)
+			continue;
+		if (cache[i] != wm8978_reg[i])
+			snd_soc_write(codec, i, cache[i]);
+	}
+
+	wm8978_set_bias_level(codec, SND_SOC_BIAS_STANDBY);
+
+	if (wm8978->f_pllout)
+		/* Switch PLL on */
+		snd_soc_update_bits(codec, WM8978_POWER_MANAGEMENT_1, 0x20, 0x20);
+
+	return 0;
+}
+
+static int wm8978_probe(struct platform_device *pdev)
+{
+	struct snd_soc_device *socdev = platform_get_drvdata(pdev);
+	struct snd_soc_codec *codec;
+	int ret = 0;
+
+	if (wm8978_codec == NULL) {
+		dev_err(&pdev->dev, "Codec device not registered\n");
+		return -ENODEV;
+	}
+
+	socdev->card->codec = wm8978_codec;
+	codec = wm8978_codec;
+
+	/* register pcms */
+	ret = snd_soc_new_pcms(socdev, SNDRV_DEFAULT_IDX1, SNDRV_DEFAULT_STR1);
+	if (ret < 0) {
+		dev_err(codec->dev, "failed to create pcms: %d\n", ret);
+		goto pcm_err;
+	}
+
+	snd_soc_add_controls(codec, wm8978_snd_controls,
+			     ARRAY_SIZE(wm8978_snd_controls));
+	wm8978_add_widgets(codec);
+
+pcm_err:
+	return ret;
+}
+
+/* power down chip */
+static int wm8978_remove(struct platform_device *pdev)
+{
+	struct snd_soc_device *socdev = platform_get_drvdata(pdev);
+
+	snd_soc_free_pcms(socdev);
+	snd_soc_dapm_free(socdev);
+
+	return 0;
+}
+
+struct snd_soc_codec_device soc_codec_dev_wm8978 = {
+	.probe		= wm8978_probe,
+	.remove		= wm8978_remove,
+	.suspend	= wm8978_suspend,
+	.resume		= wm8978_resume,
+};
+EXPORT_SYMBOL_GPL(soc_codec_dev_wm8978);
+
+/*
+ * These registers contain an "update" bit - bit 8. This means, for example,
+ * that one can write new DAC digital volume for both channels, but only when
+ * the update bit is set, will also the volume be updated - simultaneously for
+ * both channels.
+ */
+static const int update_reg[] = {
+	WM8978_LEFT_DAC_DIGITAL_VOLUME,
+	WM8978_RIGHT_DAC_DIGITAL_VOLUME,
+	WM8978_LEFT_ADC_DIGITAL_VOLUME,
+	WM8978_RIGHT_ADC_DIGITAL_VOLUME,
+	WM8978_LEFT_INP_PGA_CONTROL,
+	WM8978_RIGHT_INP_PGA_CONTROL,
+	WM8978_LOUT1_HP_CONTROL,
+	WM8978_ROUT1_HP_CONTROL,
+	WM8978_LOUT2_SPK_CONTROL,
+	WM8978_ROUT2_SPK_CONTROL,
+};
+
+static __devinit int wm8978_register(struct wm8978_priv *wm8978)
+{
+	int ret, i;
+	struct snd_soc_codec *codec = &wm8978->codec;
+
+	if (wm8978_codec) {
+		dev_err(codec->dev, "Another WM8978 is registered\n");
+		return -EINVAL;
+	}
+
+	/*
+	 * Set default system clock to PLL, it is more precise, this is also the
+	 * default hardware setting
+	 */
+	wm8978->sysclk = WM8978_PLL;
+
+	mutex_init(&codec->mutex);
+	INIT_LIST_HEAD(&codec->dapm_widgets);
+	INIT_LIST_HEAD(&codec->dapm_paths);
+
+	codec->private_data = wm8978;
+	codec->name = "WM8978";
+	codec->owner = THIS_MODULE;
+	codec->bias_level = SND_SOC_BIAS_OFF;
+	codec->set_bias_level = wm8978_set_bias_level;
+	codec->dai = &wm8978_dai;
+	codec->num_dai = 1;
+	codec->reg_cache_size = WM8978_CACHEREGNUM;
+	codec->reg_cache = &wm8978->reg_cache;
+
+	ret = snd_soc_codec_set_cache_io(codec, 7, 9, SND_SOC_I2C);
+	if (ret < 0) {
+		dev_err(codec->dev, "Failed to set cache I/O: %d\n", ret);
+		goto err;
+	}
+
+	memcpy(codec->reg_cache, wm8978_reg, sizeof(wm8978_reg));
+
+	/*
+	 * Set the update bit in all registers, that have one. This way all
+	 * writes to those registers will also cause the update bit to be
+	 * written.
+	 */
+	for (i = 0; i < ARRAY_SIZE(update_reg); i++)
+		((u16 *)codec->reg_cache)[update_reg[i]] |= 0x100;
+
+	/* Reset the codec */
+	ret = snd_soc_write(codec, WM8978_RESET, 0);
+	if (ret < 0) {
+		dev_err(codec->dev, "Failed to issue reset\n");
+		goto err;
+	}
+
+	wm8978_dai.dev = codec->dev;
+
+	wm8978_set_bias_level(codec, SND_SOC_BIAS_STANDBY);
+
+	wm8978_codec = codec;
+
+	ret = snd_soc_register_codec(codec);
+	if (ret != 0) {
+		dev_err(codec->dev, "Failed to register codec: %d\n", ret);
+		goto err;
+	}
+
+	ret = snd_soc_register_dai(&wm8978_dai);
+	if (ret != 0) {
+		dev_err(codec->dev, "Failed to register DAI: %d\n", ret);
+		goto err_codec;
+	}
+
+	return 0;
+
+err_codec:
+	snd_soc_unregister_codec(codec);
+err:
+	kfree(wm8978);
+	return ret;
+}
+
+static __devexit void wm8978_unregister(struct wm8978_priv *wm8978)
+{
+	wm8978_set_bias_level(&wm8978->codec, SND_SOC_BIAS_OFF);
+	snd_soc_unregister_dai(&wm8978_dai);
+	snd_soc_unregister_codec(&wm8978->codec);
+	kfree(wm8978);
+	wm8978_codec = NULL;
+}
+
+static __devinit int wm8978_i2c_probe(struct i2c_client *i2c,
+				      const struct i2c_device_id *id)
+{
+	struct wm8978_priv *wm8978;
+	struct snd_soc_codec *codec;
+
+	wm8978 = kzalloc(sizeof(struct wm8978_priv), GFP_KERNEL);
+	if (wm8978 == NULL)
+		return -ENOMEM;
+
+	codec = &wm8978->codec;
+	codec->hw_write = (hw_write_t)i2c_master_send;
+
+	i2c_set_clientdata(i2c, wm8978);
+	codec->control_data = i2c;
+
+	codec->dev = &i2c->dev;
+
+	return wm8978_register(wm8978);
+}
+
+static __devexit int wm8978_i2c_remove(struct i2c_client *client)
+{
+	struct wm8978_priv *wm8978 = i2c_get_clientdata(client);
+	wm8978_unregister(wm8978);
+	return 0;
+}
+
+static const struct i2c_device_id wm8978_i2c_id[] = {
+	{ "wm8978", 0 },
+	{ }
+};
+MODULE_DEVICE_TABLE(i2c, wm8978_i2c_id);
+
+static struct i2c_driver wm8978_i2c_driver = {
+	.driver = {
+		.name = "WM8978",
+		.owner = THIS_MODULE,
+	},
+	.probe =    wm8978_i2c_probe,
+	.remove =   __devexit_p(wm8978_i2c_remove),
+	.id_table = wm8978_i2c_id,
+};
+
+static int __init wm8978_modinit(void)
+{
+	return i2c_add_driver(&wm8978_i2c_driver);
+}
+module_init(wm8978_modinit);
+
+static void __exit wm8978_exit(void)
+{
+	i2c_del_driver(&wm8978_i2c_driver);
+}
+module_exit(wm8978_exit);
+
+MODULE_DESCRIPTION("ASoC WM8978 codec driver");
+MODULE_AUTHOR("Guennadi Liakhovetski <g.liakhovetski@gmx.de>");
+MODULE_LICENSE("GPL");