1 files changed, 274 insertions, 0 deletions

diff --git a/firmware/drivers/audio/ak4376.c b/firmware/drivers/audio/ak4376.c
new file mode 100644
index 0000000000..494bbabfa4
--- /dev/null
+++ b/firmware/drivers/audio/ak4376.c
@@ -0,0 +1,274 @@
+/***************************************************************************
+ *             __________               __   ___.
+ *   Open      \______   \ ____   ____ |  | _\_ |__   _______  ___
+ *   Source     |       _//  _ \_/ ___\|  |/ /| __ \ /  _ \  \/  /
+ *   Jukebox    |    |   (  <_> )  \___|    < | \_\ (  <_> > <  <
+ *   Firmware   |____|_  /\____/ \___  >__|_ \|___  /\____/__/\_ \
+ *                     \/            \/     \/    \/            \/
+ * $Id$
+ *
+ * Copyright (C) 2021 Aidan MacDonald
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version 2
+ * of the License, or (at your option) any later version.
+ *
+ * This software is distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY
+ * KIND, either express or implied.
+ *
+ ****************************************************************************/
+
+#include "audiohw.h"
+#include "sound.h"
+#include "panic.h"
+#include "pcm_sampr.h"
+#include "pcm_sw_volume.h"
+#include "system.h"
+#include "i2c-async.h"
+
+#ifndef HAVE_SW_VOLUME_CONTROL
+# error "AK4376 requires HAVE_SW_VOLUME_CONTROL!"
+#endif
+
+/* NOTE: At present, only the FiiO M3K uses this driver so the handling of
+ * the clock / audio interface is limited to I2S slave, 16-bit samples, with
+ * DAC master clock provided directly on the MCLK input pin, fitting the
+ * clock setup of the M3K.
+ *
+ * Feel free to expand upon this if another target ever needs this driver.
+ */
+
+/* Converts HW_FREQ_XX constants to register values */
+static const int ak4376_fsel_to_hw[] = {
+    HW_HAVE_192_(AK4376_FS_192,)
+    HW_HAVE_176_(AK4376_FS_176,)
+    HW_HAVE_96_(AK4376_FS_96,)
+    HW_HAVE_88_(AK4376_FS_88,)
+    HW_HAVE_64_(AK4376_FS_64,)
+    HW_HAVE_48_(AK4376_FS_48,)
+    HW_HAVE_44_(AK4376_FS_44,)
+    HW_HAVE_32_(AK4376_FS_32,)
+    HW_HAVE_24_(AK4376_FS_24,)
+    HW_HAVE_22_(AK4376_FS_22,)
+    HW_HAVE_16_(AK4376_FS_16,)
+    HW_HAVE_12_(AK4376_FS_12,)
+    HW_HAVE_11_(AK4376_FS_11,)
+    HW_HAVE_8_(AK4376_FS_8,)
+};
+
+static struct ak4376 {
+    int fsel;
+    int low_mode;
+    int regs[AK4376_NUM_REGS];
+} ak4376;
+
+void ak4376_init(void)
+{
+    /* Initialize DAC state */
+    ak4376.fsel = HW_FREQ_48;
+    ak4376.low_mode = 0;
+    for(int i = 0; i < AK4376_NUM_REGS; ++i)
+        ak4376.regs[i] = -1;
+
+    /* Initial reset after power-on */
+    ak4376_set_pdn_pin(0);
+    mdelay(1);
+    ak4376_set_pdn_pin(1);
+    mdelay(1);
+
+    static const int init_config[] = {
+        /* Ensure HPRHZ, HPLHZ are 0 */
+        AK4376_REG_OUTPUT_MODE,  0x00,
+        /* Mute all volume controls */
+        AK4376_REG_MIXER,        0x00,
+        AK4376_REG_LCH_VOLUME,   0x80,
+        AK4376_REG_RCH_VOLUME,   0x00,
+        AK4376_REG_AMP_VOLUME,   0x00,
+        /* Clock source = MCLK, divider = 1 */
+        AK4376_REG_DAC_CLK_SRC,  0x00,
+        AK4376_REG_DAC_CLK_DIV,  0x00,
+        /* I2S slave mode, 16-bit samples */
+        AK4376_REG_AUDIO_IF_FMT, 0x03,
+        /* Recommended by datasheet */
+        AK4376_REG_ADJUST1,      0x20,
+        AK4376_REG_ADJUST2,      0x05,
+        /* Power controls */
+        AK4376_REG_PWR2,         0x33,
+        AK4376_REG_PWR3,         0x01,
+        AK4376_REG_PWR4,         0x03,
+    };
+
+    /* Write initial configuration prior to power-up */
+    for(size_t i = 0; i < ARRAYLEN(init_config); i += 2)
+        ak4376_write(init_config[i], init_config[i+1]);
+
+    /* Initial frequency setting, also handles DAC/amp power-up */
+    audiohw_set_frequency(HW_FREQ_48);
+}
+
+void ak4376_close(void)
+{
+    /* Shut off power */
+    ak4376_write(AK4376_REG_PWR3, 0x00);
+    ak4376_write(AK4376_REG_PWR4, 0x00);
+    ak4376_write(AK4376_REG_PWR2, 0x00);
+
+    /* PDN pin low */
+    ak4376_set_pdn_pin(0);
+}
+
+void ak4376_write(int reg, int value)
+{
+    /* Ensure value is sensible and differs from the last set value */
+    if((value & 0xff) == value && ak4376.regs[reg] != value) {
+        int r = i2c_reg_write1(AK4376_BUS, AK4376_ADDR, reg, value);
+        if(r == I2C_STATUS_OK)
+            ak4376.regs[reg] = value;
+        else
+            ak4376.regs[reg] = -1;
+    }
+}
+
+int ak4376_read(int reg)
+{
+    /* Only read from I2C if we don't already know the value */
+    if(ak4376.regs[reg] < 0)
+        ak4376.regs[reg] = i2c_reg_read1(AK4376_BUS, AK4376_ADDR, reg);
+
+    return ak4376.regs[reg];
+}
+
+static int round_step_up(int x, int step)
+{
+    int rem = x % step;
+    if(rem > 0)
+        rem -= step;
+    return x - rem;
+}
+
+static void calc_volumes(int vol, int* mix, int* dig, int* sw)
+{
+    /* Mixer can divide by 2, which gives an extra -6 dB adjustment */
+    if(vol < AK4376_DIG_VOLUME_MIN) {
+        *mix |= AK4376_MIX_HALF;
+        vol += 60;
+    }
+
+    *dig = round_step_up(vol, AK4376_DIG_VOLUME_STEP);
+    *dig = MIN(*dig, AK4376_DIG_VOLUME_MAX);
+    *dig = MAX(*dig, AK4376_DIG_VOLUME_MIN);
+    vol -= *dig;
+
+    /* Seems that this is the allowable range for software volume */
+    *sw = MIN(vol, 60);
+    *sw = MAX(*sw, -730);
+    vol -= *sw;
+}
+
+static int dig_vol_to_hw(int vol)
+{
+    if(vol < AK4376_DIG_VOLUME_MIN) return 0;
+    if(vol > AK4376_DIG_VOLUME_MAX) return 31;
+    return (vol - AK4376_DIG_VOLUME_MIN) / AK4376_DIG_VOLUME_STEP + 1;
+}
+
+static int amp_vol_to_hw(int vol)
+{
+    if(vol < AK4376_AMP_VOLUME_MIN) return 0;
+    if(vol > AK4376_AMP_VOLUME_MAX) return 14;
+    return (vol - AK4376_AMP_VOLUME_MIN) / AK4376_AMP_VOLUME_STEP + 1;
+}
+
+void audiohw_set_volume(int vol_l, int vol_r)
+{
+    int amp;
+    int mix_l = AK4376_MIX_LCH, dig_l, sw_l;
+    int mix_r = AK4376_MIX_RCH, dig_r, sw_r;
+
+    if(vol_l <= AK4376_MIN_VOLUME && vol_r <= AK4376_MIN_VOLUME) {
+        /* Special case for full mute */
+        amp = AK4376_AMP_VOLUME_MUTE;
+        dig_l = dig_r = AK4376_DIG_VOLUME_MUTE;
+        sw_l = sw_r = PCM_MUTE_LEVEL;
+    } else {
+        /* Amp is a mono control -- calculate based on the loudest channel.
+         * The quieter channel then gets reduced more by digital controls. */
+        amp = round_step_up(MAX(vol_l, vol_r), AK4376_AMP_VOLUME_STEP);
+        amp = MIN(amp, AK4376_AMP_VOLUME_MAX);
+        amp = MAX(amp, AK4376_AMP_VOLUME_MIN);
+
+        /* Other controls are stereo */
+        calc_volumes(vol_l - amp, &mix_l, &dig_l, &sw_l);
+        calc_volumes(vol_r - amp, &mix_r, &dig_r, &sw_r);
+    }
+
+    ak4376_write(AK4376_REG_MIXER, (mix_l & 0xf) | ((mix_r & 0xf) << 4));
+    ak4376_write(AK4376_REG_LCH_VOLUME, dig_vol_to_hw(dig_l) | (1 << 7));
+    ak4376_write(AK4376_REG_RCH_VOLUME, dig_vol_to_hw(dig_r));
+    ak4376_write(AK4376_REG_AMP_VOLUME, amp_vol_to_hw(amp));
+    pcm_set_master_volume(sw_l, sw_r);
+}
+
+void audiohw_set_filter_roll_off(int val)
+{
+    int reg = ak4376_read(AK4376_REG_FILTER);
+    reg &= ~0xc0;
+    reg |= (val & 3) << 6;
+    ak4376_write(AK4376_REG_FILTER, reg);
+}
+
+void audiohw_set_frequency(int fsel)
+{
+    /* Determine master clock multiplier */
+    int mult = ak4376_set_mclk_freq(fsel, false);
+
+    /* Calculate clock mode for frequency. Multipliers of 32/64 are only
+     * for rates >= 256 KHz which are not supported by Rockbox, so they
+     * are commented out -- but they're in the correct place. */
+    int clock_mode = ak4376_fsel_to_hw[fsel];
+    switch(mult) {
+    /* case 32: */
+    case 256:
+        break;
+    /* case 64: */
+    case 512:
+        clock_mode |= 0x20;
+        break;
+    case 1024:
+        clock_mode |= 0x40;
+        break;
+    case 128:
+        clock_mode |= 0x60;
+        break;
+    default:
+        panicf("ak4376: bad master clock multiple %d", mult);
+        return;
+    }
+
+    /* Handle the DSMLP bit in the MODE_CTRL register */
+    int mode_ctrl = 0x00;
+    if(ak4376.low_mode || hw_freq_sampr[fsel] <= SAMPR_12)
+        mode_ctrl |= 0x40;
+
+    /* Program the new settings */
+    ak4376_write(AK4376_REG_CLOCK_MODE, clock_mode);
+    ak4376_write(AK4376_REG_MODE_CTRL, mode_ctrl);
+    ak4376_write(AK4376_REG_PWR3, ak4376.low_mode ? 0x11 : 0x01);
+
+    /* Enable the master clock */
+    ak4376_set_mclk_freq(fsel, true);
+
+    /* Remember the frequency */
+    ak4376.fsel = fsel;
+}
+
+void audiohw_set_power_mode(int mode)
+{
+    /* This is handled via audiohw_set_frequency() since changing LPMODE
+     * bit requires power-down/power-up & changing other bits as well */
+    if(ak4376.low_mode != mode) {
+        ak4376.low_mode = mode;
+        audiohw_set_frequency(ak4376.fsel);
+    }
+}