ASoC: arizona: Implement stability check for LHPF coefficients

Specifying unstable coefficients for the low/high pass filters can have
a severe impact on the audio. This patchs adds a stability check on the
coefficients written to the low/high pass filter block to prevent this.
Signed-off-by: Charles Keepax <ckeepax@opensource.wolfsonmicro.com>
Signed-off-by: Mark Brown <broonie@kernel.org>

sound/soc/codecs/arizona.c

@@ -2372,6 +2372,23 @@ int arizona_eq_coeff_put(struct snd_kcontrol *kcontrol,
 }
 EXPORT_SYMBOL_GPL(arizona_eq_coeff_put);
 
+int arizona_lhpf_coeff_put(struct snd_kcontrol *kcontrol,
+			   struct snd_ctl_elem_value *ucontrol)
+{
+	struct snd_soc_codec *codec = snd_soc_kcontrol_codec(kcontrol);
+	struct arizona *arizona = dev_get_drvdata(codec->dev->parent);
+	__be16 *data = (__be16 *)ucontrol->value.bytes.data;
+	s16 val = be16_to_cpu(*data);
+
+	if (abs(val) >= 4096) {
+		dev_err(arizona->dev, "Rejecting unstable LHPF coefficients\n");
+		return -EINVAL;
+	}
+
+	return snd_soc_bytes_put(kcontrol, ucontrol);
+}
+EXPORT_SYMBOL_GPL(arizona_lhpf_coeff_put);
+
 MODULE_DESCRIPTION("ASoC Wolfson Arizona class device support");
 MODULE_AUTHOR("Mark Brown <broonie@opensource.wolfsonmicro.com>");
 MODULE_LICENSE("GPL");

sound/soc/codecs/arizona.h

@@ -201,6 +201,13 @@ extern int arizona_mixer_values[ARIZONA_NUM_MIXER_INPUTS];
 	((unsigned long)&(struct soc_bytes) { .base = xbase,  \
 	 .num_regs = 20, .mask = ~ARIZONA_EQ1_B1_MODE }) }
 
+#define ARIZONA_LHPF_CONTROL(xname, xbase)                    \
+{	.iface = SNDRV_CTL_ELEM_IFACE_MIXER, .name = xname,   \
+	.info = snd_soc_bytes_info, .get = snd_soc_bytes_get, \
+	.put = arizona_lhpf_coeff_put, .private_value =       \
+	((unsigned long)&(struct soc_bytes) { .base = xbase,  \
+	 .num_regs = 1 }) }
+
 #define ARIZONA_RATE_ENUM_SIZE 4
 extern const char *arizona_rate_text[ARIZONA_RATE_ENUM_SIZE];
 extern const int arizona_rate_val[ARIZONA_RATE_ENUM_SIZE];
@@ -238,6 +245,8 @@ extern int arizona_hp_ev(struct snd_soc_dapm_widget *w,
 
 extern int arizona_eq_coeff_put(struct snd_kcontrol *kcontrol,
 				struct snd_ctl_elem_value *ucontrol);
+extern int arizona_lhpf_coeff_put(struct snd_kcontrol *kcontrol,
+				  struct snd_ctl_elem_value *ucontrol);
 
 extern int arizona_set_sysclk(struct snd_soc_codec *codec, int clk_id,
 			      int source, unsigned int freq, int dir);

sound/soc/codecs/wm5102.c

@@ -847,10 +847,10 @@ ARIZONA_MIXER_CONTROLS("LHPF2", ARIZONA_HPLP2MIX_INPUT_1_SOURCE),
 ARIZONA_MIXER_CONTROLS("LHPF3", ARIZONA_HPLP3MIX_INPUT_1_SOURCE),
 ARIZONA_MIXER_CONTROLS("LHPF4", ARIZONA_HPLP4MIX_INPUT_1_SOURCE),
 
-SND_SOC_BYTES("LHPF1 Coefficients", ARIZONA_HPLPF1_2, 1),
-SND_SOC_BYTES("LHPF2 Coefficients", ARIZONA_HPLPF2_2, 1),
-SND_SOC_BYTES("LHPF3 Coefficients", ARIZONA_HPLPF3_2, 1),
-SND_SOC_BYTES("LHPF4 Coefficients", ARIZONA_HPLPF4_2, 1),
+ARIZONA_LHPF_CONTROL("LHPF1 Coefficients", ARIZONA_HPLPF1_2),
+ARIZONA_LHPF_CONTROL("LHPF2 Coefficients", ARIZONA_HPLPF2_2),
+ARIZONA_LHPF_CONTROL("LHPF3 Coefficients", ARIZONA_HPLPF3_2),
+ARIZONA_LHPF_CONTROL("LHPF4 Coefficients", ARIZONA_HPLPF4_2),
 
 ARIZONA_MIXER_CONTROLS("DSP1L", ARIZONA_DSP1LMIX_INPUT_1_SOURCE),
 ARIZONA_MIXER_CONTROLS("DSP1R", ARIZONA_DSP1RMIX_INPUT_1_SOURCE),

sound/soc/codecs/wm5110.c

@@ -310,10 +310,10 @@ ARIZONA_MIXER_CONTROLS("LHPF2", ARIZONA_HPLP2MIX_INPUT_1_SOURCE),
 ARIZONA_MIXER_CONTROLS("LHPF3", ARIZONA_HPLP3MIX_INPUT_1_SOURCE),
 ARIZONA_MIXER_CONTROLS("LHPF4", ARIZONA_HPLP4MIX_INPUT_1_SOURCE),
 
-SND_SOC_BYTES("LHPF1 Coefficients", ARIZONA_HPLPF1_2, 1),
-SND_SOC_BYTES("LHPF2 Coefficients", ARIZONA_HPLPF2_2, 1),
-SND_SOC_BYTES("LHPF3 Coefficients", ARIZONA_HPLPF3_2, 1),
-SND_SOC_BYTES("LHPF4 Coefficients", ARIZONA_HPLPF4_2, 1),
+ARIZONA_LHPF_CONTROL("LHPF1 Coefficients", ARIZONA_HPLPF1_2),
+ARIZONA_LHPF_CONTROL("LHPF2 Coefficients", ARIZONA_HPLPF2_2),
+ARIZONA_LHPF_CONTROL("LHPF3 Coefficients", ARIZONA_HPLPF3_2),
+ARIZONA_LHPF_CONTROL("LHPF4 Coefficients", ARIZONA_HPLPF4_2),
 
 SOC_ENUM("LHPF1 Mode", arizona_lhpf1_mode),
 SOC_ENUM("LHPF2 Mode", arizona_lhpf2_mode),

sound/soc/codecs/wm8997.c

@@ -238,10 +238,10 @@ SOC_ENUM("LHPF2 Mode", arizona_lhpf2_mode),
 SOC_ENUM("LHPF3 Mode", arizona_lhpf3_mode),
 SOC_ENUM("LHPF4 Mode", arizona_lhpf4_mode),
 
-SND_SOC_BYTES("LHPF1 Coefficients", ARIZONA_HPLPF1_2, 1),
-SND_SOC_BYTES("LHPF2 Coefficients", ARIZONA_HPLPF2_2, 1),
-SND_SOC_BYTES("LHPF3 Coefficients", ARIZONA_HPLPF3_2, 1),
-SND_SOC_BYTES("LHPF4 Coefficients", ARIZONA_HPLPF4_2, 1),
+ARIZONA_LHPF_CONTROL("LHPF1 Coefficients", ARIZONA_HPLPF1_2),
+ARIZONA_LHPF_CONTROL("LHPF2 Coefficients", ARIZONA_HPLPF2_2),
+ARIZONA_LHPF_CONTROL("LHPF3 Coefficients", ARIZONA_HPLPF3_2),
+ARIZONA_LHPF_CONTROL("LHPF4 Coefficients", ARIZONA_HPLPF4_2),
 
 SOC_ENUM("ISRC1 FSL", arizona_isrc_fsl[0]),
 SOC_ENUM("ISRC2 FSL", arizona_isrc_fsl[1]),