experiments/ohmmeter.py: Make CS42L84 your ohmmeter

Add script which prints out the (rough) measured impedance of connected
headphones on machines with the CS42L84 jack codec (2021 Macbook Pros).

  $ proxyclient/experiments/ohmmeter.py
  Waiting for plug... measuring... 64.3 ohms... yanked
  Waiting for plug... measuring... 697.1 ohms...

Signed-off-by: Martin Povišer <povik@protonmail.com>

proxyclient/experiments/ohmmeter.py

@@ -0,0 +1,260 @@
+#!/usr/bin/env python3
+# SPDX-License-Identifier: MIT
+import sys, pathlib
+import time
+sys.path.append(str(pathlib.Path(__file__).resolve().parents[1]))
+
+from m1n1.utils import *
+from enum import IntEnum
+from m1n1.setup import *
+from m1n1.hw.i2c import I2C
+
+
+class R_IRQ_MASK1(Register8):
+    RING_PLUG   = 0
+    RING_UNPLUG = 1
+    TIP_PLUG    = 2
+    TIP_UNPLUG  = 3
+
+class E_DCID_GND_SEL(IntEnum):
+    NONE = 0
+    HS3  = 1
+    HS4  = 2
+
+class E_DCID_Z_RANGE(IntEnum):
+    NONE = 0
+    UNK2 = 2
+    UNK3 = 3
+
+class R_DCID_CTRL1(Register8):
+    Z_RANGE = 2, 0, E_DCID_Z_RANGE
+
+class R_DCID_CTRL2(Register8):
+    GND_SEL = 6, 4, E_DCID_GND_SEL
+
+class R_DCID_CTRL3(Register8):
+    START = 0
+
+class R_DCID_STATUS(Register32):
+    OVERALL = 9, 0
+    DONE    = 10
+    U       = 20, 11
+    D       = 30, 21
+
+class E_DEBOUNCE_TIME(IntEnum):
+    T_0MS   = 0b000
+    T_125MS = 0b001
+    T_250MS = 0b010
+    T_500MS = 0b011
+    T_750MS = 0b100
+    T_1S    = 0b101
+
+class R_TR_SENSE_CTRL(Register8):
+    INV      = 7
+    UNK1     = 6
+    FALLTIME = 5, 3, E_DEBOUNCE_TIME
+    RISETIME = 2, 0, E_DEBOUNCE_TIME
+
+class R_TR_SENSE_STATUS(Register8):
+    RING_PLUG   = 0
+    RING_UNPLUG = 1
+    TIP_PLUG    = 2
+    TIP_UNPLUG  = 3
+
+class R_MSM_BLOCK_EN3(Register8):
+    TR_SENSE_EN = 3
+    DCID_EN     = 4
+
+class R_MSM_CLAMP_CTRL(Register8):
+    HS_CLAMP_DISABLE = 0
+
+class E_SAMP_RATE(IntEnum):
+    S_16KHZ   = 1
+    S_24KHZ   = 2
+    S_32KHZ   = 3
+    S_48KHZ   = 4
+    S_96KHZ   = 5
+    S_192KHZ  = 6
+    S_22K05HZ = 10
+    S_44K1HZ  = 12
+    S_88K2HZ  = 13
+    S_176K4HZ = 14
+
+class R_CCM_SAMP_RATE(Register8):
+    RATE = 7, 0, E_SAMP_RATE
+
+class R_DAC_CTRL1(Register8):
+    HP_LOAD = 2 # maybe
+    UNK2    = 4
+    UNK3    = 5 # always set
+    HIGH_V  = 6
+
+class E_PULLDOWN_R(IntEnum):
+    NONE      = 0x0
+    R_UNK8    = 0x8
+    R_1K1OHMS = 0xc
+
+class R_DAC_CTRL2(Register8):
+    PULLDOWN_R = 3, 0, E_PULLDOWN_R
+
+class CS42L84Registers(RegMap):
+    DEVID  = irange(0x0, 5), Register8
+    FREEZE = 0x6, Register8
+
+    SW_RESET = 0x203, Register8
+
+    IRQ_STATUS = irange(0x400, 3), Register8
+    IRQ_MASK1  = 0x418, R_IRQ_MASK1
+    IRQ_MASK2  = 0x419, Register8
+    IRQ_MASK3  = 0x41a, Register8
+
+    CCM_CTRL         = irange(0x600, 4), Register8
+    CCM_SAMP_RATE    = 0x601, R_CCM_SAMP_RATE
+    CCM_ASP_CLK_CTRL = 0x608, Register8
+
+    PLL_CTRL     = 0x800, Register8
+    PLL_DIV_FRAC = irange(0x804, 3), Register8
+    PLL_DIV_INT  = 0x807, Register8
+    PLL_DIVOUT   = 0x808, Register8
+
+    DCID_CTRL1          = 0x1200, R_DCID_CTRL1
+    DCID_CTRL2          = 0x1201, R_DCID_CTRL2
+    DCID_CTRL3          = 0x1202, R_DCID_CTRL3
+    DCID_TRIM_OFFSET    = 0x1207, Register8
+    DCID_TRIM_SLOPE     = 0x120a, Register8
+
+    # R_pull = 1100 - (regval - 128)*2
+    DCID_PULLDOWN_TRIM  = 0x120b, Register8
+    DCID_STATUS         = 0x120c, R_DCID_STATUS
+
+    # tip/ring sense
+    TR_SENSE_CTRL1  = 0x1280, Register8
+    TR_SENSE_CTRL2  = 0x1281, Register8
+    RING_SENSE_CTRL = 0x1282, R_TR_SENSE_CTRL
+    TIP_SENSE_CTRL  = 0x1283, R_TR_SENSE_CTRL
+    TR_SENSE_STATUS = 0x1288, R_TR_SENSE_STATUS
+
+    MIKEY_CTRL1 = 0x1472
+    MIKEY_CTRL2 = 0x1473, Register8
+
+    MSM_BLOCK_EN3  = 0x1802, R_MSM_BLOCK_EN3
+    MSM_CLAMP_CTRL = 0x1813, R_MSM_CLAMP_CTRL
+    ADC_CTRL     = irange(0x2000, 4), Register8
+
+    DAC_CTRL1     = 0x3000, R_DAC_CTRL1
+    DAC_CTRL2     = 0x3001, R_DAC_CTRL2
+    DACA_VOL_LSB  = 0x3004, Register8
+    DACA_VOL_MSB  = 0x3005, Register8 # sign bit
+    DACB_VOL_LSB  = 0x3006, Register8
+    DACB_VOL_MSB  = 0x3007, Register8 # sign bit
+    HP_VOL_CTRL   = 0x3020, Register8
+    HP_CLAMP_CTRL = 0x3123, Register8
+
+    ASP_CTRL       = 0x5000, Register8
+    ASP_FSYNC_CTRL = irange(0x500f, 3), Register8
+    ASP_DATA_CTRL  = 0x5018, Register8
+
+    ASP_RX_EN = 0x5020, Register8
+    ASP_TX_EN = 0x5024, Register8
+
+    ASP_RXSLOT_CH1_LSB = 0x5028, Register8
+    ASP_RXSLOT_CH1_MSB = 0x5029, Register8
+
+    ASP_RXSLOT_CH2_LSB = 0x502c, Register8
+    ASP_RXSLOT_CH2_MSB = 0x502d, Register8
+
+    ASP_TXSLOT_CH1_LSB = 0x5068, Register8
+    ASP_TXSLOT_CH1_MSB = 0x5068, Register8
+
+
+class CS42L84:
+    def __init__(self, bus, addr):
+        self.regs = CS42L84Registers(self, 0)
+        self.bus = bus
+        self.addr = addr
+
+    def write(self, regaddr, val, width=8):
+        valbytes = val.to_bytes(width//8, byteorder="little")
+        self.bus.write_reg(self.addr, regaddr, valbytes, regaddrlen=2)
+
+    def read(self, regaddr, width=8):
+        read = self.bus.read_reg(self.addr, regaddr, width//8, regaddrlen=2)
+        return int.from_bytes(read, byteorder='little')
+
+
+def read_devid():
+    pass
+
+def sense_Z():
+    r = l84.regs
+
+    r.MSM_CLAMP_CTRL.set(HS_CLAMP_DISABLE=1)
+    r.DAC_CTRL2.set(PULLDOWN_R=E_PULLDOWN_R.R_1K1OHMS)
+    r.DCID_CTRL1.set(Z_RANGE=E_DCID_Z_RANGE.UNK2)
+    r.DCID_CTRL2.set(GND_SEL=E_DCID_GND_SEL.HS3)
+    r.MSM_BLOCK_EN3.set(DCID_EN=1)
+    r.DCID_CTRL3.set(START=0)
+    r.DCID_CTRL3.set(START=1)
+
+    while not r.DCID_STATUS.reg.DONE:
+        pass
+
+    reading = r.DCID_STATUS.reg.OVERALL
+    offset_trim = r.DCID_TRIM_OFFSET.val - 128
+    slope_trim = r.DCID_TRIM_SLOPE.val - 128
+    pulldown_trim = r.DCID_PULLDOWN_TRIM.val - 128
+
+    Y_overall = ((reading + 0.5) * 0.01086 - 1.0 / (1 - slope_trim * 0.001375)) \
+        / (614.0 + offset_trim * 0.125)
+    Y_pulldown = 1.0 / (1100 - pulldown_trim*2)
+
+    if Y_overall > Y_pulldown:
+        Z_headphones = 1.0 / (Y_overall - Y_pulldown)
+    else:
+        Z_headphones = float('inf')
+
+    r.MSM_BLOCK_EN3.set(DCID_EN=0)
+    r.DAC_CTRL2.set(PULLDOWN_R=E_PULLDOWN_R.NONE)
+
+    return Z_headphones
+
+def init_ring_tip_sense():
+    l84.write(0x1471, 0xe0)
+    l84.write(0x1473, 0xc0)
+    l84.write(0x1477, 0x02)
+    l84.write(0x1478, 0x8f)
+
+    l84.regs.RING_SENSE_CTRL.set(INV=1, UNK1=1,
+        RISETIME=E_DEBOUNCE_TIME.T_125MS, FALLTIME=E_DEBOUNCE_TIME.T_125MS)
+    l84.regs.TIP_SENSE_CTRL.set(INV=1,
+        RISETIME=E_DEBOUNCE_TIME.T_500MS, FALLTIME=E_DEBOUNCE_TIME.T_125MS)
+    l84.regs.MSM_BLOCK_EN3.set(TR_SENSE_EN=1)
+
+def wait_for_plug():
+    while not l84.regs.TR_SENSE_STATUS.reg.TIP_PLUG:
+        time.sleep(0.001)
+
+def wait_for_unplug():
+    while l84.regs.TR_SENSE_STATUS.reg.TIP_UNPLUG:
+        time.sleep(0.001)
+
+
+p.pmgr_adt_clocks_enable("/arm-io/i2c2")
+i2c2 = I2C(u, "/arm-io/i2c2")
+
+p.write32(0x2921f0010, 0x76a02) # invoke reset
+p.write32(0x2921f0010, 0x76a03) # out of reset
+
+l84 = CS42L84(i2c2, 0x4b)
+
+init_ring_tip_sense()
+
+while True:
+    print("Waiting for plug... ", end=""); sys.stdout.flush()
+    wait_for_plug()
+
+    print("measuring... ", end=""); sys.stdout.flush()
+    print(f"{sense_Z():.1f} ohms... ", end=""); sys.stdout.flush()
+
+    wait_for_unplug()
+    print("yanked")