zenxfi3: rewrite mpr121 driver

The new driver uses an asynchronous architecture for touch status reading.

Change-Id: Ic75a8b91bc47ee16c3af873afde178cd70186376

7 files changed, 601 insertions, 574 deletions

diff --git a/firmware/SOURCES b/firmware/SOURCES
index 34d2db39b2..db3f09ea8e 100644
--- a/firmware/SOURCES
+++ b/firmware/SOURCES
@@ -1231,10 +1231,10 @@ target/arm/imx233/creative-zenxfi2/powermgmt-zenxfi2.c
 #endif
 
 #ifdef CREATIVE_ZENXFI3
-drivers/mpr121.c
 #ifndef BOOTLOADER
 target/arm/imx233/fmradio-imx233.c
 #endif
+target/arm/imx233/creative-zenxfi3/mpr121-zenxfi3.c
 target/arm/imx233/creative-zenxfi3/backlight-zenxfi3.c
 target/arm/imx233/creative-zenxfi3/lcd-zenxfi3.c
 target/arm/imx233/creative-zenxfi3/button-zenxfi3.c
diff --git a/firmware/drivers/mpr121.c b/firmware/drivers/mpr121.c
deleted file mode 100644
index 7b41208a3a..0000000000
--- a/firmware/drivers/mpr121.c
+++ /dev/null
@@ -1,350 +0,0 @@
-/***************************************************************************
- *             __________               __   ___.
- *   Open      \______   \ ____   ____ |  | _\_ |__   _______  ___
- *   Source     |       _//  _ \_/ ___\|  |/ /| __ \ /  _ \  \/  /
- *   Jukebox    |    |   (  <_> )  \___|    < | \_\ (  <_> > <  <
- *   Firmware   |____|_  /\____/ \___  >__|_ \|___  /\____/__/\_ \
- *                     \/            \/     \/    \/            \/
- * $Id$
- *
- * Copyright (C) 2012 Amaury Pouly
- *
- * 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.
- *
- ****************************************************************************/ 
-
-/** Driver for the Freescale MPR121 Capacitive Proximity Sensor */
-#include "system.h"
-#include "mpr121.h"
-#include "i2c.h"
-
-/* Touch status: EL{0,7} */
-#define REG_TOUCH_STATUS    0x00
-#define REG_TOUCH_STATUS__ELE(x)    (1 << (x))
-/* Touch status: EL{8-11,prox}, overcurrent */
-#define REG_TOUCH_STATUS2   0x01
-#define REG_TOUCH_STATUS2__ELE(x)   (1 << ((x) - 8))
-#define REG_TOUCH_STATUS2__ELEPROX  (1 << 4)
-#define REG_TOUCH_STATUS2__OVCF     (1 << 7)
-/* Out of range: EL{0,7} */
-#define REG_OOR_STATUS      0x02
-#define REG_OOR_STATUS__ELE(x)      (1 << (x))
-/* Out of range: EL{8-11,prox}, autoconf err */
-#define REG_OOR_STATUS2     0x03
-#define REG_OOR_STATUS2__ELE(x)     (1 << (x))
-#define REG_OOR_STATUS2__ELEPROX    (1 << 4)
-#define REG_OOR_STATUS2__ACFF       (1 << 6)
-#define REG_OOR_STATUS2__ARFF       (1 << 7)
-/* Electrode X filtered data LSB */
-#define REG_EFDxLB(x)       (0x04 + 0x02 * (x))
-/* Electrode X filtered data MSB */
-#define REG_EFDxHB(x)       (0x05 + 0x02 * (x))
-/* Proximity electrode X filtered data LSB */
-#define REG_EFDPROXLB       0x1c
-/* Proximity electrode X filtered data MSB */
-#define REG_EFDPROXHB       0x1d
-/* Electrode baseline value */
-#define REG_ExBV(x)         (0x1e + (x))
-/* Proximity electrode baseline value */
-#define REG_EPROXBV         0x2a
-/* Max Half Delta Rising */
-#define REG_MHDR            0x2b
-/* Noise Half Delta Rising */
-#define REG_NHDR            0x2c
-/* Noise Count Limit Rising */
-#define REG_NCLR            0x2d
-/* Filter Delay Limit Rising */
-#define REG_FDLR            0x2e
-/* Max Half Delta Falling */
-#define REG_MHDF            0x2f
-/* Noise Half Delta Falling */
-#define REG_NHDF            0x30
-/* Noise Count Limit Falling */
-#define REG_NCLF            0x31
-/* Filter Delay Limit Falling */
-#define REG_FDLF            0x32
-/* Noise Half Delta Touched */
-#define REG_NHDT            0x33
-/* Noise Count Limit Touched */
-#define REG_NCLT            0x34
-/* Filter Delay Limit Touched */
-#define REG_FDLT            0x35
-/* Proximity Max Half Delta Rising */
-#define REG_MHDPROXR        0x36
-/* Proximity Noise Half Delta Rising */
-#define REG_NHDPROXR        0x37
-/* Proximity Noise Count Limit Rising */
-#define REG_NCLPROXR        0x38
-/* Proximity Filter Delay Limit Rising */
-#define REG_FDLPROXR        0x39
-/* Proximity Max Half Delta Falling */
-#define REG_MHDPROXF        0x3a
-/* Proximity Noise Half Delta Falling */
-#define REG_NHDPROXF        0x3b
-/* Proximity Noise Count Limit Falling */
-#define REG_NCLPROXF        0x3c
-/* Proximity Filter Delay Limit Falling */
-#define REG_FDLPROXF        0x3d
-/* Proximity Noise Half Delta Touched */
-#define REG_NHDPROXT        0x3e
-/* Proximity Noise Count Limit Touched */
-#define REG_NCLPROXT        0x3f
-/* Proximity Filter Delay Limit Touched */
-#define REG_FDLPROXT        0x40
-/* Eletrode Touch Threshold */
-#define REG_ExTTH(x)        (0x41 + 2 * (x))
-/* Eletrode Release Threshold */
-#define REG_ExRTH(x)        (0x42 + 2 * (x))
-/* Proximity Eletrode Touch Threshold */
-#define REG_EPROXTTH        0x59
-/* Proximity Eletrode Release Threshold */
-#define REG_EPROXRTH        0x5a
-/* Debounce Control */
-#define REG_DEBOUNCE        0x5b
-#define REG_DEBOUNCE__DR(dr)    ((dr) << 4)
-#define REG_DEBOUNCE__DT(dt)    (dt)
-/* Analog Front End Configuration */
-#define REG_AFE             0x5c
-#define REG_AFE__CDC(cdc)   (cdc)
-#define REG_AFE__FFI(ffi)   ((ffi) << 6)
-/* Filter Configuration */
-#define REG_FILTER          0x5d
-#define REG_FILTER__ESI(esi)    (esi)
-#define REG_FILTER__SFI(sfi)    ((sfi) << 3)
-#define REG_FILTER__CDT(cdt)    ((cdt) << 5)
-/* Electrode Configuration */
-#define REG_ELECTRODE       0x5e
-#define REG_ELECTRODE__ELE_EN(en)       (en)
-#define REG_ELECTRODE__ELEPROX_EN(en)   ((en) << 4)
-#define REG_ELECTRODE__CL(cl)   ((cl) << 6)
-/* Electrode X Current */
-#define REG_CDCx(x)         (0x5f + (x))
-/* Proximity Eletrode X Current */
-#define REG_CDCPROX         0x6b
-/* Electrode X Charge Time */
-#define REG_CDTx(x)         (0x6c + (x) / 2)
-#define REG_CDTx__CDT0(x)   (x)
-#define REG_CDTx__CDT1(x)   ((x) << 4)
-/* Proximity Eletrode X Charge Time  */
-#define REG_CDTPROX         0x72
-/* GPIO Control Register: CTL0{4-11} */
-#define REG_GPIO_CTL0       0x73
-#define REG_GPIO_CTL0__CTL0x(x) (1 << ((x) - 4))
-/* GPIO Control Register: CTL1{4-11} */
-#define REG_GPIO_CTL1       0x74
-#define REG_GPIO_CTL1__CTL1x(x) (1 << ((x) - 4))
-/* GPIO Data Register */
-#define REG_GPIO_DATA       0x75
-#define REG_GPIO_DATA__DATx(x)  (1 << ((x) - 4))
-/* GPIO Direction Register */
-#define REG_GPIO_DIR        0x76
-#define REG_GPIO_DIR__DIRx(x)   (1 << ((x) - 4))
-/* GPIO Enable Register */
-#define REG_GPIO_EN         0x77
-#define REG_GPIO_EN__ENx(x)     (1 << ((x) - 4))
-/* GPIO Data Set Register */
-#define REG_GPIO_SET        0x78
-#define REG_GPIO_SET__SETx(x)   (1 << ((x) - 4))
-/* GPIO Data Clear Register */
-#define REG_GPIO_CLR        0x79
-#define REG_GPIO_CLR__CLRx(x)   (1 << ((x) - 4))
-/* GPIO Data Toggle Register */
-#define REG_GPIO_TOG        0x7a
-#define REG_GPIO_TOG__TOGx(x)   (1 << ((x) - 4))
-/* Auto-Configuration Control 0 */
-#define REG_AUTO_CONF       0x7b
-#define REG_AUTO_CONF__ACE(ace)     (ace)
-#define REG_AUTO_CONF__ARE(are)     ((are) << 1)
-#define REG_AUTO_CONF__BVA(bva)     ((bva) << 2)
-#define REG_AUTO_CONF__RETRY(retry) ((retry) << 4)
-#define REG_AUTO_CONF__FFI(ffi)     ((ffi) << 6)
-/* Auto-Configuration Control 1 */
-#define REG_AUTO_CONF2      0x7c
-#define REG_AUTO_CONF2__ACFIE(acfie)    (acfie)
-#define REG_AUTO_CONF2__ARFIE(arfie)    ((arfie) << 1)
-#define REG_AUTO_CONF2__OORIE(oorie)    ((oorie) << 2)
-#define REG_AUTO_CONF2__SCTS(scts)      ((scts) << 7)
-/* Auto-Configuration Upper-Limit */
-#define REG_USL             0x7d
-/* Auto-Configuration Lower-Limit */
-#define REG_LSL             0x7e
-/* Auto-Configuration Target Level */
-#define REG_TL              0x7f
-/* Soft-Reset */
-#define REG_SOFTRESET       0x80
-#define REG_SOFTRESET__MAGIC    0x63
-/* PWM Control */
-#define REG_PWMx(x)         (0x81 + ((x) - 4) / 2)
-#define REG_PWMx_IS_PWM0(x) (((x) % 2) == 0)
-#define REG_PWMx__PWM0(x)   (x)
-#define REG_PWMx__PWM0_BM   0xf
-#define REG_PWMx__PWM1(x)   ((x) << 4)
-#define REG_PWMx__PWM1_BM   0xf0
-
-static int i2c_addr;
-
-static inline int mpr121_write_reg(uint8_t reg, uint8_t data)
-{
-    return i2c_writemem(i2c_addr, reg, &data, 1);
-}
-
-static inline int mpr121_read_reg(uint8_t reg, uint8_t *data)
-{
-    return i2c_readmem(i2c_addr, reg, data, 1);
-}
-
-int mpr121_init(int dev_i2c_addr)
-{
-    i2c_addr =  dev_i2c_addr;
-    return 0;
-}
-
-int mpr121_soft_reset(void)
-{
-    return mpr121_write_reg(REG_SOFTRESET, REG_SOFTRESET__MAGIC);
-}
-int mpr121_set_config(struct mpr121_config_t *conf)
-{
-    int ret;
-#define safe_write(reg, val) \
-    do { ret = mpr121_write_reg(reg, val); \
-    if(ret) return ret; } while(0)
-    /* stop mode */
-    safe_write(REG_ELECTRODE, 0);
-    /* write baseline values */
-    for(int i = 0; i < ELECTRODE_COUNT; i++)
-        safe_write(REG_ExBV(i), conf->ele[i].bv);
-    /* write eleprox bv */
-    safe_write(REG_EPROXBV, conf->eleprox.bv);
-    /* write global fields */
-    safe_write(REG_MHDR, conf->filters.ele.rising.mhd);
-    safe_write(REG_NHDR, conf->filters.ele.rising.nhd);
-    safe_write(REG_NCLR, conf->filters.ele.rising.ncl);
-    safe_write(REG_FDLR, conf->filters.ele.rising.fdl);
-    safe_write(REG_MHDF, conf->filters.ele.falling.mhd);
-    safe_write(REG_NHDF, conf->filters.ele.falling.nhd);
-    safe_write(REG_NCLF, conf->filters.ele.falling.ncl);
-    safe_write(REG_FDLF, conf->filters.ele.falling.fdl);
-    safe_write(REG_NHDT, conf->filters.ele.touched.nhd);
-    safe_write(REG_NCLT, conf->filters.ele.touched.ncl);
-    safe_write(REG_FDLT, conf->filters.ele.touched.fdl);
-    safe_write(REG_MHDPROXR, conf->filters.eleprox.rising.mhd);
-    safe_write(REG_NHDPROXR, conf->filters.eleprox.rising.nhd);
-    safe_write(REG_NCLPROXR, conf->filters.eleprox.rising.ncl);
-    safe_write(REG_FDLPROXR, conf->filters.eleprox.rising.fdl);
-    safe_write(REG_MHDPROXF, conf->filters.eleprox.falling.mhd);
-    safe_write(REG_NHDPROXF, conf->filters.eleprox.falling.nhd);
-    safe_write(REG_NCLPROXF, conf->filters.eleprox.falling.ncl);
-    safe_write(REG_FDLPROXF, conf->filters.eleprox.falling.fdl);
-    safe_write(REG_NHDPROXT, conf->filters.eleprox.touched.nhd);
-    safe_write(REG_NCLPROXT, conf->filters.eleprox.touched.ncl);
-    safe_write(REG_FDLPROXT, conf->filters.eleprox.touched.fdl);
-    /* touch & release thresholds */
-    for(int i = 0; i < ELECTRODE_COUNT; i++)
-    {
-        safe_write(REG_ExTTH(i), conf->ele[i].tth);
-        safe_write(REG_ExRTH(i), conf->ele[i].rth);
-    }
-    safe_write(REG_EPROXTTH, conf->eleprox.tth);
-    safe_write(REG_EPROXRTH, conf->eleprox.rth);
-    /* debounce */
-    safe_write(REG_DEBOUNCE, REG_DEBOUNCE__DR(conf->debounce.dr) |
-        REG_DEBOUNCE__DT(conf->debounce.dt));
-    /* analog-front end and filters */
-    safe_write(REG_AFE, REG_AFE__CDC(conf->global.cdc) |
-        REG_AFE__FFI(conf->global.ffi));
-    safe_write(REG_FILTER, REG_FILTER__CDT(conf->global.cdt) |
-        REG_FILTER__ESI(conf->global.esi) | REG_FILTER__SFI(conf->global.sfi));
-    /* electrode charge */
-    for(int i = 0; i < ELECTRODE_COUNT; i++)
-        safe_write(REG_CDCx(i), conf->ele[i].cdc);
-    safe_write(REG_CDCPROX, conf->eleprox.cdc);
-    for(int i = 0; i < ELECTRODE_COUNT; i += 2)
-    {
-        safe_write(REG_CDTx(i), REG_CDTx__CDT0(conf->ele[i].cdt) |
-            REG_CDTx__CDT1(conf->ele[i+1].cdt));
-    }
-    safe_write(REG_CDTPROX, conf->eleprox.cdt);
-    /* Auto-Configuration */
-    safe_write(REG_AUTO_CONF, REG_AUTO_CONF__ACE(conf->autoconf.en) |
-        REG_AUTO_CONF__ARE(conf->autoconf.ren) |
-        REG_AUTO_CONF__BVA(conf->cal_lock) |
-        REG_AUTO_CONF__RETRY(conf->autoconf.retry) |
-        REG_AUTO_CONF__FFI(conf->global.ffi));
-    safe_write(REG_AUTO_CONF2, REG_AUTO_CONF2__ACFIE(conf->autoconf.acfie) |
-        REG_AUTO_CONF2__ARFIE(conf->autoconf.arfie) |
-        REG_AUTO_CONF2__OORIE(conf->autoconf.oorie) |
-        REG_AUTO_CONF2__SCTS(conf->autoconf.scts));
-    safe_write(REG_USL, conf->autoconf.usl);
-    safe_write(REG_LSL, conf->autoconf.lsl);
-    safe_write(REG_TL, conf->autoconf.tl);
-    /* electrode configuration */
-    safe_write(REG_ELECTRODE, REG_ELECTRODE__ELE_EN(conf->ele_en) |
-        REG_ELECTRODE__ELEPROX_EN(conf->eleprox_en) |
-        REG_ELECTRODE__CL(conf->cal_lock));
-    /* gpio config */
-    uint8_t ctl = 0;
-    for(int i = ELE_GPIO_FIRST; i <= ELE_GPIO_LAST; i++)
-        if(ELE_GPIO_CTL0(conf->ele[i].gpio))
-            ctl |= REG_GPIO_CTL0__CTL0x(i);
-    safe_write(REG_GPIO_CTL0, ctl);
-    ctl = 0;
-    for(int i = ELE_GPIO_FIRST; i <= ELE_GPIO_LAST; i++)
-        if(ELE_GPIO_CTL1(conf->ele[i].gpio))
-            ctl |= REG_GPIO_CTL1__CTL1x(i);
-    safe_write(REG_GPIO_CTL1, ctl);
-    ctl = 0;
-    for(int i = ELE_GPIO_FIRST; i <= ELE_GPIO_LAST; i++)
-        if(ELE_GPIO_DIR(conf->ele[i].gpio))
-            ctl |= REG_GPIO_DIR__DIRx(i);
-    safe_write(REG_GPIO_DIR, ctl);
-    ctl = 0;
-    for(int i = ELE_GPIO_FIRST; i <= ELE_GPIO_LAST; i++)
-        if(ELE_GPIO_EN(conf->ele[i].gpio))
-            ctl |= REG_GPIO_EN__ENx(i);
-    safe_write(REG_GPIO_EN, ctl);
-    
-    return 0;
-}
-
-int mpr121_set_gpio_output(int ele, int gpio_val)
-{
-    switch(gpio_val)
-    {
-        case ELE_GPIO_SET:
-            return mpr121_write_reg(REG_GPIO_SET, REG_GPIO_SET__SETx(ele));
-        case ELE_GPIO_CLR:
-            return mpr121_write_reg(REG_GPIO_CLR, REG_GPIO_CLR__CLRx(ele));
-        case ELE_GPIO_TOG:
-            return mpr121_write_reg(REG_GPIO_TOG, REG_GPIO_TOG__TOGx(ele));
-        default:
-            return -1;
-    }
-}
-
-int mpr121_set_gpio_pwm(int ele, int pwm)
-{
-    uint8_t reg_val;
-    int ret = mpr121_read_reg(REG_PWMx(ele), &reg_val);
-    if(ret) return ret;
-    if(REG_PWMx_IS_PWM0(ele))
-        reg_val = (reg_val & ~REG_PWMx__PWM0_BM) | REG_PWMx__PWM0(pwm);
-    else
-        reg_val = (reg_val & ~REG_PWMx__PWM1_BM) | REG_PWMx__PWM1(pwm);
-    return mpr121_write_reg(REG_PWMx(ele), reg_val);
-}
-
-int mpr121_get_touch_status(unsigned *status)
-{
-    uint8_t buf[2];
-    int ret = i2c_readmem(i2c_addr, REG_TOUCH_STATUS, buf, 2);
-    if(!ret && status)
-        *status = buf[0] | buf[1];
-    return ret;
-}
diff --git a/firmware/export/mpr121.h b/firmware/export/mpr121.h
index 96b83ecc90..50c13a1c7b 100644
--- a/firmware/export/mpr121.h
+++ b/firmware/export/mpr121.h
@@ -18,153 +18,173 @@
  * KIND, either express or implied.
  *
  ****************************************************************************/
+#ifndef __MPR121_H__
+#define __MPR121_H__
 
-/** Driver for the Freescale MPR121 Capacitive Proximity Sensor */
+/** Registers for the Freescale MPR121 Capacitive Proximity Sensor */
 #include "system.h"
 
-#define ELECTRODE_COUNT 12
-#define ELE_GPIO_FIRST  4
-#define ELE_GPIO_LAST   11
-
-/* gpio config (encoding: [0]=en,[1]=dir,[2]=ctl[1],[3]=ctl[0]) */
-#define ELE_GPIO_DISABLE        0
-#define ELE_GPIO_INPUT          1
-#define ELE_GPIO_INPUT_PULLDOWN 9 /* input with pull-down */
-#define ELE_GPIO_INPUT_PULLUP   13 /* input with pull-up */
-#define ELE_GPIO_OUTPUT         3
-#define ELE_GPIO_OUTPUT_OPEN     11 /* open drain low-side */
-#define ELE_GPIO_OUTPUT_OPEN_LED 15 /* open drain high-side (led driver) */
-
-/* internal use */
-#define ELE_GPIO_EN(val)    ((val) & 1)
-#define ELE_GPIO_DIR(val)   (((val) >> 1) & 1)
-#define ELE_GPIO_CTL0(val)  (((val) >> 3) & 1)
-#define ELE_GPIO_CTL1(val)  (((val) >> 1) & 1)
-
-struct mpr121_electrode_config_t
-{
-    uint8_t bv; /* baseline value */
-    uint8_t tth; /* touch threshold */
-    uint8_t rth; /* release threshold */
-    uint8_t cdc; /* charge current (optional if auto-conf) */
-    uint8_t cdt; /* charge time (optional if auto-conf) */
-    int gpio; /* gpio config */
-};
-
-struct mpr121_baseline_filter_config_t
-{
-    uint8_t mhd; /* max half delta (except for touched) */
-    uint8_t nhd; /* noise half delta */
-    uint8_t ncl; /* noise count limit */
-    uint8_t fdl; /* filter delay count limit */
-};
-
-struct mpr121_baseline_filters_config_t
-{
-    struct mpr121_baseline_filter_config_t rising;
-    struct mpr121_baseline_filter_config_t falling;
-    struct mpr121_baseline_filter_config_t touched;
-};
-
-struct mpr121_debounce_config_t
-{
-    uint8_t dt; /* debounce count for touch */
-    uint8_t dr; /* debounce count for release */
-};
-
-/* first filter iterations */
-#define FFI_6_SAMPLES   0
-#define FFI_10_SAMPLES  1
-#define FFI_18_SAMPLES  2
-#define FFI_34_SAMPLES  3
-/* charge discharge current */
-#define CDC_DISABLE     0
-#define CDC_uA(ua)      (ua)
-/* charge discharge time */
-#define CDT_DISABLE     0
-#define CDT_log_us(lus) (lus) /* actual value = 2^{us-2} µs */
-/* second filter iterations */
-#define SFI_4_SAMPLES   0
-#define SFI_6_SAMPLES   1
-#define SFI_10_SAMPLES  2
-#define SFI_18_SAMPLES  3
-/* Eletrode sample interval */
-#define ESI_log_ms(lms) (lms) /* actual value = 2^{lms} ms */
-
-struct mpr121_global_config_t
-{
-    uint8_t ffi; /* first filter iterations */
-    uint8_t cdc; /* global charge discharge current */
-    uint8_t cdt; /* global charge discharge time */
-    uint8_t sfi; /* second first iterations */
-    uint8_t esi; /* electrode sample interval */
-};
-
-#define RETRY_NEVER     0
-#define RETRY_2_TIMES   1
-#define RETRY_4_TIMES   2
-#define RETRY_8_TIMES   3
-
-struct mpr121_auto_config_t
-{
-    bool en; /* auto-conf enable */
-    bool ren; /* auto-reconf enable */
-    uint8_t retry; /* retry count */
-    bool scts; /* skip charge time search */
-    uint8_t usl; /* upper-side limit */
-    uint8_t lsl; /* lower-side limit */
-    uint8_t tl; /* target level */
-    bool acfie; /* auto-conf fail interrupt en */
-    bool arfie; /* auto-reconf fail interrupt en */
-    bool oorie; /* out of range interrupt en */
-};
-
-/* electrode mode */
-#define ELE_DISABLE     0
-#define ELE_EN0_x(x)    ((x) + 1)
-/* eleprox mode */
-#define ELEPROX_DISABLE 0
-#define ELEPROX_EN0_1   1
-#define ELEPROX_EN0_3   2
-#define ELEPROX_EN0_11  3
-/* calibration lock */
-#define CL_SLOW_TRACK   0
-#define CL_DISABLE      1
-#define CL_TRACK        2
-#define CL_FAST_TRACK   3
-
-struct mpr121_config_t
-{
-    struct mpr121_electrode_config_t ele[ELECTRODE_COUNT];
-    struct mpr121_electrode_config_t eleprox;
-    struct
-    {
-        struct mpr121_baseline_filters_config_t ele;
-        struct mpr121_baseline_filters_config_t eleprox;
-    }filters;
-    struct mpr121_debounce_config_t debounce;
-    struct mpr121_global_config_t global;
-    struct mpr121_auto_config_t autoconf;
-    uint8_t ele_en; /* eletroce mode */
-    uint8_t eleprox_en; /* proximity mode */
-    uint8_t cal_lock; /* calibration lock */
-};
-
-/* gpio value */
-#define ELE_GPIO_CLR    0
-#define ELE_GPIO_SET    1
-#define ELE_GPIO_TOG    2
-/* pwm value */
-#define ELE_PWM_DISABLE 0
-#define ELE_PWM_DUTY(x) (x)
-#define ELE_PWM_MIN_DUTY    1
-#define ELE_PWM_MAX_DUTY    15
-
-int mpr121_init(int dev_i2c_addr);
-int mpr121_soft_reset(void);
-int mpr121_set_config(struct mpr121_config_t *conf);
-/* gpios are only implemented for electrode>=4 */
-int mpr121_set_gpio_output(int ele, int gpio_val);
-int mpr121_set_gpio_pwm(int ele, int pwm);
-/* get electrode status (bitmap) */
-int mpr121_get_touch_status(unsigned *status);
+/* Touch status: EL{0,7} */
+#define REG_TOUCH_STATUS    0x00
+#define REG_TOUCH_STATUS__ELE(x)    (1 << (x))
+/* Touch status: EL{8-11,prox}, overcurrent */
+#define REG_TOUCH_STATUS2   0x01
+#define REG_TOUCH_STATUS2__ELE(x)   (1 << ((x) - 8))
+#define REG_TOUCH_STATUS2__ELEPROX  (1 << 4)
+#define REG_TOUCH_STATUS2__OVCF     (1 << 7)
+/* Out of range: EL{0,7} */
+#define REG_OOR_STATUS      0x02
+#define REG_OOR_STATUS__ELE(x)      (1 << (x))
+/* Out of range: EL{8-11,prox}, autoconf err */
+#define REG_OOR_STATUS2     0x03
+#define REG_OOR_STATUS2__ELE(x)     (1 << (x))
+#define REG_OOR_STATUS2__ELEPROX    (1 << 4)
+#define REG_OOR_STATUS2__ACFF       (1 << 6)
+#define REG_OOR_STATUS2__ARFF       (1 << 7)
+/* Electrode X filtered data LSB */
+#define REG_EFDxLB(x)       (0x04 + 0x02 * (x))
+/* Electrode X filtered data MSB */
+#define REG_EFDxHB(x)       (0x05 + 0x02 * (x))
+/* Proximity electrode X filtered data LSB */
+#define REG_EFDPROXLB       0x1c
+/* Proximity electrode X filtered data MSB */
+#define REG_EFDPROXHB       0x1d
+/* Electrode baseline value */
+#define REG_ExBV(x)         (0x1e + (x))
+/* Proximity electrode baseline value */
+#define REG_EPROXBV         0x2a
+/* Max Half Delta Rising */
+#define REG_MHDR            0x2b
+/* Noise Half Delta Rising */
+#define REG_NHDR            0x2c
+/* Noise Count Limit Rising */
+#define REG_NCLR            0x2d
+/* Filter Delay Limit Rising */
+#define REG_FDLR            0x2e
+/* Max Half Delta Falling */
+#define REG_MHDF            0x2f
+/* Noise Half Delta Falling */
+#define REG_NHDF            0x30
+/* Noise Count Limit Falling */
+#define REG_NCLF            0x31
+/* Filter Delay Limit Falling */
+#define REG_FDLF            0x32
+/* Noise Half Delta Touched */
+#define REG_NHDT            0x33
+/* Noise Count Limit Touched */
+#define REG_NCLT            0x34
+/* Filter Delay Limit Touched */
+#define REG_FDLT            0x35
+/* Proximity Max Half Delta Rising */
+#define REG_MHDPROXR        0x36
+/* Proximity Noise Half Delta Rising */
+#define REG_NHDPROXR        0x37
+/* Proximity Noise Count Limit Rising */
+#define REG_NCLPROXR        0x38
+/* Proximity Filter Delay Limit Rising */
+#define REG_FDLPROXR        0x39
+/* Proximity Max Half Delta Falling */
+#define REG_MHDPROXF        0x3a
+/* Proximity Noise Half Delta Falling */
+#define REG_NHDPROXF        0x3b
+/* Proximity Noise Count Limit Falling */
+#define REG_NCLPROXF        0x3c
+/* Proximity Filter Delay Limit Falling */
+#define REG_FDLPROXF        0x3d
+/* Proximity Noise Half Delta Touched */
+#define REG_NHDPROXT        0x3e
+/* Proximity Noise Count Limit Touched */
+#define REG_NCLPROXT        0x3f
+/* Proximity Filter Delay Limit Touched */
+#define REG_FDLPROXT        0x40
+/* Eletrode Touch Threshold */
+#define REG_ExTTH(x)        (0x41 + 2 * (x))
+/* Eletrode Release Threshold */
+#define REG_ExRTH(x)        (0x42 + 2 * (x))
+/* Proximity Eletrode Touch Threshold */
+#define REG_EPROXTTH        0x59
+/* Proximity Eletrode Release Threshold */
+#define REG_EPROXRTH        0x5a
+/* Debounce Control */
+#define REG_DEBOUNCE        0x5b
+#define REG_DEBOUNCE__DR(dr)    ((dr) << 4)
+#define REG_DEBOUNCE__DT(dt)    (dt)
+/* Analog Front End Configuration */
+#define REG_AFE             0x5c
+#define REG_AFE__CDC(cdc)   (cdc)
+#define REG_AFE__FFI(ffi)   ((ffi) << 6)
+/* Filter Configuration */
+#define REG_FILTER          0x5d
+#define REG_FILTER__ESI(esi)    (esi)
+#define REG_FILTER__SFI(sfi)    ((sfi) << 3)
+#define REG_FILTER__CDT(cdt)    ((cdt) << 5)
+/* Electrode Configuration */
+#define REG_ELECTRODE       0x5e
+#define REG_ELECTRODE__ELE_EN(en)       (en)
+#define REG_ELECTRODE__ELEPROX_EN(en)   ((en) << 4)
+#define REG_ELECTRODE__CL(cl)   ((cl) << 6)
+/* Electrode X Current */
+#define REG_CDCx(x)         (0x5f + (x))
+/* Proximity Eletrode X Current */
+#define REG_CDCPROX         0x6b
+/* Electrode X Charge Time */
+#define REG_CDTx(x)         (0x6c + (x) / 2)
+#define REG_CDTx__CDT0(x)   (x)
+#define REG_CDTx__CDT1(x)   ((x) << 4)
+/* Proximity Eletrode X Charge Time  */
+#define REG_CDTPROX         0x72
+/* GPIO Control Register: CTL0{4-11} */
+#define REG_GPIO_CTL0       0x73
+#define REG_GPIO_CTL0__CTL0x(x) (1 << ((x) - 4))
+/* GPIO Control Register: CTL1{4-11} */
+#define REG_GPIO_CTL1       0x74
+#define REG_GPIO_CTL1__CTL1x(x) (1 << ((x) - 4))
+/* GPIO Data Register */
+#define REG_GPIO_DATA       0x75
+#define REG_GPIO_DATA__DATx(x)  (1 << ((x) - 4))
+/* GPIO Direction Register */
+#define REG_GPIO_DIR        0x76
+#define REG_GPIO_DIR__DIRx(x)   (1 << ((x) - 4))
+/* GPIO Enable Register */
+#define REG_GPIO_EN         0x77
+#define REG_GPIO_EN__ENx(x)     (1 << ((x) - 4))
+/* GPIO Data Set Register */
+#define REG_GPIO_SET        0x78
+#define REG_GPIO_SET__SETx(x)   (1 << ((x) - 4))
+/* GPIO Data Clear Register */
+#define REG_GPIO_CLR        0x79
+#define REG_GPIO_CLR__CLRx(x)   (1 << ((x) - 4))
+/* GPIO Data Toggle Register */
+#define REG_GPIO_TOG        0x7a
+#define REG_GPIO_TOG__TOGx(x)   (1 << ((x) - 4))
+/* Auto-Configuration Control 0 */
+#define REG_AUTO_CONF       0x7b
+#define REG_AUTO_CONF__ACE(ace)     (ace)
+#define REG_AUTO_CONF__ARE(are)     ((are) << 1)
+#define REG_AUTO_CONF__BVA(bva)     ((bva) << 2)
+#define REG_AUTO_CONF__RETRY(retry) ((retry) << 4)
+#define REG_AUTO_CONF__FFI(ffi)     ((ffi) << 6)
+/* Auto-Configuration Control 1 */
+#define REG_AUTO_CONF2      0x7c
+#define REG_AUTO_CONF2__ACFIE(acfie)    (acfie)
+#define REG_AUTO_CONF2__ARFIE(arfie)    ((arfie) << 1)
+#define REG_AUTO_CONF2__OORIE(oorie)    ((oorie) << 2)
+#define REG_AUTO_CONF2__SCTS(scts)      ((scts) << 7)
+/* Auto-Configuration Upper-Limit */
+#define REG_USL             0x7d
+/* Auto-Configuration Lower-Limit */
+#define REG_LSL             0x7e
+/* Auto-Configuration Target Level */
+#define REG_TL              0x7f
+/* Soft-Reset */
+#define REG_SOFTRESET       0x80
+#define REG_SOFTRESET__MAGIC    0x63
+/* PWM Control */
+#define REG_PWMx(x)         (0x81 + ((x) - 4) / 2)
+#define REG_PWMx_IS_PWM0(x) (((x) % 2) == 0)
+#define REG_PWMx__PWM0(x)   (x)
+#define REG_PWMx__PWM0_BM   0xf
+#define REG_PWMx__PWM1(x)   ((x) << 4)
+#define REG_PWMx__PWM1_BM   0xf0
+
+#endif /* __MPR121_H__ */
diff --git a/firmware/target/arm/imx233/creative-zenxfi3/backlight-zenxfi3.c b/firmware/target/arm/imx233/creative-zenxfi3/backlight-zenxfi3.c
index 2b77a4d7ac..e3baddea1e 100644
--- a/firmware/target/arm/imx233/creative-zenxfi3/backlight-zenxfi3.c
+++ b/firmware/target/arm/imx233/creative-zenxfi3/backlight-zenxfi3.c
@@ -25,7 +25,7 @@
 #include "backlight.h"
 #include "backlight-target.h"
 #include "pwm-imx233.h"
-#include "mpr121.h"
+#include "mpr121-zenxfi3.h"
 
 void backlight_hw_brightness(int brightness)
 {
diff --git a/firmware/target/arm/imx233/creative-zenxfi3/button-zenxfi3.c b/firmware/target/arm/imx233/creative-zenxfi3/button-zenxfi3.c
index 756231a042..ed8e769e2d 100644
--- a/firmware/target/arm/imx233/creative-zenxfi3/button-zenxfi3.c
+++ b/firmware/target/arm/imx233/creative-zenxfi3/button-zenxfi3.c
@@ -18,16 +18,10 @@
  * KIND, either express or implied.
  *
  ****************************************************************************/
-#include "button-target.h"
 #include "system.h"
-#include "system-target.h"
-#include "pinctrl-imx233.h"
-#include "power-imx233.h"
+#include "tick.h"
 #include "button-imx233.h"
-#include "string.h"
-#include "usb.h"
-#include "backlight.h"
-#include "mpr121.h"
+#include "mpr121-zenxfi3.h"
 
 #define I_VDDIO 0 /* index in the table */
 
@@ -42,7 +36,8 @@ struct imx233_button_map_t imx233_button_map[] =
     IMX233_BUTTON_(END, END(), "")
 };
 
-static struct mpr121_config_t config =
+/* MPR121 configuration, mostly extracted from OF */
+static struct mpr121_config_t mpr121_config =
 {
     .ele =
     {
@@ -73,74 +68,11 @@ static struct mpr121_config_t config =
     .cal_lock = CL_TRACK
 };
 
-#define MPR121_INTERRUPT    1
-
-static int touchpad_btns = 0;
-static long mpr121_stack[DEFAULT_STACK_SIZE/sizeof(long)];
-static const char mpr121_thread_name[] = "mpr121";
-static struct event_queue mpr121_queue;
-
-static void mpr121_irq_cb(int bank, int pin, intptr_t user)
-{
-    (void) bank;
-    (void) pin;
-    (void) user;
-    /* the callback will not be fired until interrupt is enabled back so
-     * the queue will not overflow or contain multiple MPR121_INTERRUPT events */
-    queue_post(&mpr121_queue, MPR121_INTERRUPT, 0);
-}
-
-static void mpr121_thread(void)
-{
-    struct queue_event ev;
-
-    while(1)
-    {
-        queue_wait(&mpr121_queue, &ev);
-        /* handle usb connect and ignore all messages except rmi interrupts */
-        if(ev.id == SYS_USB_CONNECTED)
-        {
-            usb_acknowledge(SYS_USB_CONNECTED_ACK);
-            continue;
-        }
-        else if(ev.id != MPR121_INTERRUPT)
-            continue;
-        /* clear interrupt and get status */
-        unsigned status;
-        touchpad_btns = 0;
-        if(!mpr121_get_touch_status(&status))
-        {
-            /* ELE3: up
-             * ELE4: back
-             * ELE5: menu
-             * ELE6: down
-             * ELE7: play */
-            if(status & 0x8) touchpad_btns |= BUTTON_UP;
-            if(status & 0x10) touchpad_btns |= BUTTON_BACK;
-            if(status & 0x20) touchpad_btns |= BUTTON_MENU;
-            if(status & 0x40) touchpad_btns |= BUTTON_DOWN;
-            if(status & 0x80) touchpad_btns |= BUTTON_PLAY;
-        }
-        /* enable interrupt */
-        imx233_pinctrl_setup_irq(0, 18, true, true, false, &mpr121_irq_cb, 0);
-    }
-}
-
 /* B0P18 is #IRQ line of the touchpad */
 void button_init_device(void)
 {
-    mpr121_init(0xb4);
-    mpr121_soft_reset();
-    mpr121_set_config(&config);
-
-    queue_init(&mpr121_queue, true);
-    create_thread(mpr121_thread, mpr121_stack, sizeof(mpr121_stack), 0,
-        mpr121_thread_name IF_PRIO(, PRIORITY_USER_INTERFACE) IF_COP(, CPU));
-    /* enable interrupt */
-    imx233_pinctrl_acquire(0, 18, "mpr121_int");
-    imx233_pinctrl_set_function(0, 18, PINCTRL_FUNCTION_GPIO);
-    imx233_pinctrl_enable_gpio(0, 18, false);
-    imx233_pinctrl_setup_irq(0, 18, true, true, false, &mpr121_irq_cb, 0);
+    mpr121_init();
+    mpr121_set_config(&mpr121_config);
     /* generic part */
     imx233_button_init();
 }
@@ -151,7 +83,6 @@ int button_read_device(void)
      * for one second after hold is released */
     static int power_ignore_counter = 0;
     static bool old_hold;
-    /* light handling */
     bool hold = button_hold();
     if(hold != old_hold)
     {
@@ -159,6 +90,20 @@ int button_read_device(void)
         if(!hold)
             power_ignore_counter = HZ;
     }
+    /* interpret touchpad status */
+    unsigned status = mpr121_get_touch_status();
+    unsigned touchpad_btns = 0;
+    /* ELE3: up
+     * ELE4: back
+     * ELE5: menu
+     * ELE6: down
+     * ELE7: play */
+    if(status & 0x8) touchpad_btns |= BUTTON_UP;
+    if(status & 0x10) touchpad_btns |= BUTTON_BACK;
+    if(status & 0x20) touchpad_btns |= BUTTON_MENU;
+    if(status & 0x40) touchpad_btns |= BUTTON_DOWN;
+    if(status & 0x80) touchpad_btns |= BUTTON_PLAY;
+    /* feed it to generic code */
     int res = imx233_button_read(touchpad_btns);
     if(power_ignore_counter > 0)
     {
diff --git a/firmware/target/arm/imx233/creative-zenxfi3/mpr121-zenxfi3.c b/firmware/target/arm/imx233/creative-zenxfi3/mpr121-zenxfi3.c
new file mode 100644
index 0000000000..23fcc7f0e4
--- /dev/null
+++ b/firmware/target/arm/imx233/creative-zenxfi3/mpr121-zenxfi3.c
@@ -0,0 +1,236 @@
+/***************************************************************************
+ *             __________               __   ___.
+ *   Open      \______   \ ____   ____ |  | _\_ |__   _______  ___
+ *   Source     |       _//  _ \_/ ___\|  |/ /| __ \ /  _ \  \/  /
+ *   Jukebox    |    |   (  <_> )  \___|    < | \_\ (  <_> > <  <
+ *   Firmware   |____|_  /\____/ \___  >__|_ \|___  /\____/__/\_ \
+ *                     \/            \/     \/    \/            \/
+ * $Id$
+ *
+ * Copyright (C) 2012 Amaury Pouly
+ *
+ * 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.
+ *
+ ****************************************************************************/ 
+
+/** Driver for the Freescale MPR121 Capacitive Proximity Sensor */
+#include "system.h"
+#include "kernel.h"
+#include "usb.h"
+#include "mpr121.h"
+#include "mpr121-zenxfi3.h"
+#include "i2c-imx233.h"
+#include "pinctrl-imx233.h"
+
+#define MPR121_I2C_ADDR     0xb4
+
+/* NOTE on the architecture of the driver
+ *
+ * All non-time-critical operations (setup, gpio/pwm changes) are done with
+ * blocking i2c transfers to make the code simpler. Since reading the touch
+ * status is time critical, it is done asynchronously: when the IRQ pin is
+ * asserted, it will disable IRQ pin sensing and trigger an asynchronous i2c
+ * transfer to read touch status. When the transfer finishes, the driver will
+ * renable IRQ pin sensing. */
+
+static unsigned touch_status = 0; /* touch bitmask as reported by mpr121 */
+static struct imx233_i2c_xfer_t read_status_xfer; /* async transfer to read touch status */
+static uint8_t read_status_sel_reg; /* buffer for async transfer operation */
+static uint8_t read_status_buf[2]; /* buffer for async transfer operation */
+
+static void mpr121_irq_cb(int bank, int pin, intptr_t user);
+
+static void touch_status_i2c_cb(struct imx233_i2c_xfer_t *xfer, enum imx233_i2c_error_t status)
+{
+    (void) xfer;
+    (void) status;
+    /* put status in the global variable */
+    touch_status = read_status_buf[0] | read_status_buf[1] << 8;
+    /* start sensing IRQ pin again */
+    imx233_pinctrl_setup_irq(0, 18, true, true, false, &mpr121_irq_cb, 0);
+}
+
+void mpr121_irq_cb(int bank, int pin, intptr_t user)
+{
+    (void) bank;
+    (void) pin;
+    (void) user;
+    /* NOTE the callback will not be fired until interrupt is enabled back.
+     *
+     * now setup an asynchronous i2c transfer to read touch status register,
+     * this is a readmem operation with a first stage to select register
+     * and a second stage to read status (2 bytes) */
+    read_status_sel_reg = REG_TOUCH_STATUS;
+
+    read_status_xfer.next = NULL;
+    read_status_xfer.fast_mode = true;
+    read_status_xfer.dev_addr = MPR121_I2C_ADDR;
+    read_status_xfer.mode = I2C_READ;
+    read_status_xfer.count[0] = 1; /* set touch status register address */
+    read_status_xfer.data[0] = &read_status_sel_reg;
+    read_status_xfer.count[1] = 2;
+    read_status_xfer.data[1] = &read_status_buf;
+    read_status_xfer.tmo_ms = 1000;
+    read_status_xfer.callback = &touch_status_i2c_cb;
+
+    imx233_i2c_transfer(&read_status_xfer);
+}
+
+static inline int mpr121_write_reg(uint8_t reg, uint8_t data)
+{
+    return i2c_writemem(MPR121_I2C_ADDR, reg, &data, 1);
+}
+
+static inline int mpr121_read_reg(uint8_t reg, uint8_t *data)
+{
+    return i2c_readmem(MPR121_I2C_ADDR, reg, data, 1);
+}
+
+void mpr121_init(void)
+{
+    /* soft reset */
+    mpr121_write_reg(REG_SOFTRESET, REG_SOFTRESET__MAGIC);
+    /* enable interrupt */
+    imx233_pinctrl_acquire(0, 18, "mpr121_int");
+    imx233_pinctrl_set_function(0, 18, PINCTRL_FUNCTION_GPIO);
+    imx233_pinctrl_enable_gpio(0, 18, false);
+    imx233_pinctrl_setup_irq(0, 18, true, true, false, &mpr121_irq_cb, 0);
+}
+
+void mpr121_set_config(struct mpr121_config_t *conf)
+{
+    /* stop mode */
+    mpr121_write_reg(REG_ELECTRODE, 0);
+    /* write baseline values */
+    for(int i = 0; i < ELECTRODE_COUNT; i++)
+        mpr121_write_reg(REG_ExBV(i), conf->ele[i].bv);
+    /* write eleprox bv */
+    mpr121_write_reg(REG_EPROXBV, conf->eleprox.bv);
+    /* write global fields */
+    mpr121_write_reg(REG_MHDR, conf->filters.ele.rising.mhd);
+    mpr121_write_reg(REG_NHDR, conf->filters.ele.rising.nhd);
+    mpr121_write_reg(REG_NCLR, conf->filters.ele.rising.ncl);
+    mpr121_write_reg(REG_FDLR, conf->filters.ele.rising.fdl);
+    mpr121_write_reg(REG_MHDF, conf->filters.ele.falling.mhd);
+    mpr121_write_reg(REG_NHDF, conf->filters.ele.falling.nhd);
+    mpr121_write_reg(REG_NCLF, conf->filters.ele.falling.ncl);
+    mpr121_write_reg(REG_FDLF, conf->filters.ele.falling.fdl);
+    mpr121_write_reg(REG_NHDT, conf->filters.ele.touched.nhd);
+    mpr121_write_reg(REG_NCLT, conf->filters.ele.touched.ncl);
+    mpr121_write_reg(REG_FDLT, conf->filters.ele.touched.fdl);
+    mpr121_write_reg(REG_MHDPROXR, conf->filters.eleprox.rising.mhd);
+    mpr121_write_reg(REG_NHDPROXR, conf->filters.eleprox.rising.nhd);
+    mpr121_write_reg(REG_NCLPROXR, conf->filters.eleprox.rising.ncl);
+    mpr121_write_reg(REG_FDLPROXR, conf->filters.eleprox.rising.fdl);
+    mpr121_write_reg(REG_MHDPROXF, conf->filters.eleprox.falling.mhd);
+    mpr121_write_reg(REG_NHDPROXF, conf->filters.eleprox.falling.nhd);
+    mpr121_write_reg(REG_NCLPROXF, conf->filters.eleprox.falling.ncl);
+    mpr121_write_reg(REG_FDLPROXF, conf->filters.eleprox.falling.fdl);
+    mpr121_write_reg(REG_NHDPROXT, conf->filters.eleprox.touched.nhd);
+    mpr121_write_reg(REG_NCLPROXT, conf->filters.eleprox.touched.ncl);
+    mpr121_write_reg(REG_FDLPROXT, conf->filters.eleprox.touched.fdl);
+    /* touch & release thresholds */
+    for(int i = 0; i < ELECTRODE_COUNT; i++)
+    {
+        mpr121_write_reg(REG_ExTTH(i), conf->ele[i].tth);
+        mpr121_write_reg(REG_ExRTH(i), conf->ele[i].rth);
+    }
+    mpr121_write_reg(REG_EPROXTTH, conf->eleprox.tth);
+    mpr121_write_reg(REG_EPROXRTH, conf->eleprox.rth);
+    /* debounce */
+    mpr121_write_reg(REG_DEBOUNCE, REG_DEBOUNCE__DR(conf->debounce.dr) |
+        REG_DEBOUNCE__DT(conf->debounce.dt));
+    /* analog-front end and filters */
+    mpr121_write_reg(REG_AFE, REG_AFE__CDC(conf->global.cdc) |
+        REG_AFE__FFI(conf->global.ffi));
+    mpr121_write_reg(REG_FILTER, REG_FILTER__CDT(conf->global.cdt) |
+        REG_FILTER__ESI(conf->global.esi) | REG_FILTER__SFI(conf->global.sfi));
+    /* electrode charge */
+    for(int i = 0; i < ELECTRODE_COUNT; i++)
+        mpr121_write_reg(REG_CDCx(i), conf->ele[i].cdc);
+    mpr121_write_reg(REG_CDCPROX, conf->eleprox.cdc);
+    for(int i = 0; i < ELECTRODE_COUNT; i += 2)
+    {
+        mpr121_write_reg(REG_CDTx(i), REG_CDTx__CDT0(conf->ele[i].cdt) |
+            REG_CDTx__CDT1(conf->ele[i+1].cdt));
+    }
+    mpr121_write_reg(REG_CDTPROX, conf->eleprox.cdt);
+    /* Auto-Configuration */
+    mpr121_write_reg(REG_AUTO_CONF, REG_AUTO_CONF__ACE(conf->autoconf.en) |
+        REG_AUTO_CONF__ARE(conf->autoconf.ren) |
+        REG_AUTO_CONF__BVA(conf->cal_lock) |
+        REG_AUTO_CONF__RETRY(conf->autoconf.retry) |
+        REG_AUTO_CONF__FFI(conf->global.ffi));
+    mpr121_write_reg(REG_AUTO_CONF2, REG_AUTO_CONF2__ACFIE(conf->autoconf.acfie) |
+        REG_AUTO_CONF2__ARFIE(conf->autoconf.arfie) |
+        REG_AUTO_CONF2__OORIE(conf->autoconf.oorie) |
+        REG_AUTO_CONF2__SCTS(conf->autoconf.scts));
+    mpr121_write_reg(REG_USL, conf->autoconf.usl);
+    mpr121_write_reg(REG_LSL, conf->autoconf.lsl);
+    mpr121_write_reg(REG_TL, conf->autoconf.tl);
+    /* electrode configuration */
+    mpr121_write_reg(REG_ELECTRODE, REG_ELECTRODE__ELE_EN(conf->ele_en) |
+        REG_ELECTRODE__ELEPROX_EN(conf->eleprox_en) |
+        REG_ELECTRODE__CL(conf->cal_lock));
+    /* gpio config */
+    uint8_t ctl = 0;
+    for(int i = ELE_GPIO_FIRST; i <= ELE_GPIO_LAST; i++)
+        if(ELE_GPIO_CTL0(conf->ele[i].gpio))
+            ctl |= REG_GPIO_CTL0__CTL0x(i);
+    mpr121_write_reg(REG_GPIO_CTL0, ctl);
+    ctl = 0;
+    for(int i = ELE_GPIO_FIRST; i <= ELE_GPIO_LAST; i++)
+        if(ELE_GPIO_CTL1(conf->ele[i].gpio))
+            ctl |= REG_GPIO_CTL1__CTL1x(i);
+    mpr121_write_reg(REG_GPIO_CTL1, ctl);
+    ctl = 0;
+    for(int i = ELE_GPIO_FIRST; i <= ELE_GPIO_LAST; i++)
+        if(ELE_GPIO_DIR(conf->ele[i].gpio))
+            ctl |= REG_GPIO_DIR__DIRx(i);
+    mpr121_write_reg(REG_GPIO_DIR, ctl);
+    ctl = 0;
+    for(int i = ELE_GPIO_FIRST; i <= ELE_GPIO_LAST; i++)
+        if(ELE_GPIO_EN(conf->ele[i].gpio))
+            ctl |= REG_GPIO_EN__ENx(i);
+    mpr121_write_reg(REG_GPIO_EN, ctl);
+}
+
+void mpr121_set_gpio_output(int ele, int gpio_val)
+{
+    switch(gpio_val)
+    {
+        case ELE_GPIO_SET:
+            mpr121_write_reg(REG_GPIO_SET, REG_GPIO_SET__SETx(ele));
+            break;
+        case ELE_GPIO_CLR:
+            mpr121_write_reg(REG_GPIO_CLR, REG_GPIO_CLR__CLRx(ele));
+            break;
+        case ELE_GPIO_TOG:
+            mpr121_write_reg(REG_GPIO_TOG, REG_GPIO_TOG__TOGx(ele));
+            break;
+        default:
+            break;
+    }
+}
+
+void mpr121_set_gpio_pwm(int ele, int pwm)
+{
+    uint8_t reg_val;
+    mpr121_read_reg(REG_PWMx(ele), &reg_val);
+    if(REG_PWMx_IS_PWM0(ele))
+        reg_val = (reg_val & ~REG_PWMx__PWM0_BM) | REG_PWMx__PWM0(pwm);
+    else
+        reg_val = (reg_val & ~REG_PWMx__PWM1_BM) | REG_PWMx__PWM1(pwm);
+    mpr121_write_reg(REG_PWMx(ele), reg_val);
+}
+
+unsigned mpr121_get_touch_status(void)
+{
+    return touch_status;
+}
diff --git a/firmware/target/arm/imx233/creative-zenxfi3/mpr121-zenxfi3.h b/firmware/target/arm/imx233/creative-zenxfi3/mpr121-zenxfi3.h
new file mode 100644
index 0000000000..eb8b00eeee
--- /dev/null
+++ b/firmware/target/arm/imx233/creative-zenxfi3/mpr121-zenxfi3.h
@@ -0,0 +1,176 @@
+/***************************************************************************
+ *             __________               __   ___.
+ *   Open      \______   \ ____   ____ |  | _\_ |__   _______  ___
+ *   Source     |       _//  _ \_/ ___\|  |/ /| __ \ /  _ \  \/  /
+ *   Jukebox    |    |   (  <_> )  \___|    < | \_\ (  <_> > <  <
+ *   Firmware   |____|_  /\____/ \___  >__|_ \|___  /\____/__/\_ \
+ *                     \/            \/     \/    \/            \/
+ * $Id$
+ *
+ * Copyright (C) 2016 Amaury Pouly
+ *
+ * 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.
+ *
+ ****************************************************************************/
+#ifndef __MPR121_ZENXFI3_H__
+#define __MPR121_ZENXFI3_H__
+
+/** Driver for the Freescale MPR121 Capacitive Proximity Sensor */
+#include "system.h"
+
+#define ELECTRODE_COUNT 12
+#define ELE_GPIO_FIRST  4
+#define ELE_GPIO_LAST   11
+
+/* gpio config (encoding: [0]=en,[1]=dir,[2]=ctl[1],[3]=ctl[0]) */
+#define ELE_GPIO_DISABLE        0
+#define ELE_GPIO_INPUT          1
+#define ELE_GPIO_INPUT_PULLDOWN 9 /* input with pull-down */
+#define ELE_GPIO_INPUT_PULLUP   13 /* input with pull-up */
+#define ELE_GPIO_OUTPUT         3
+#define ELE_GPIO_OUTPUT_OPEN     11 /* open drain low-side */
+#define ELE_GPIO_OUTPUT_OPEN_LED 15 /* open drain high-side (led driver) */
+
+/* internal use */
+#define ELE_GPIO_EN(val)    ((val) & 1)
+#define ELE_GPIO_DIR(val)   (((val) >> 1) & 1)
+#define ELE_GPIO_CTL0(val)  (((val) >> 3) & 1)
+#define ELE_GPIO_CTL1(val)  (((val) >> 1) & 1)
+
+struct mpr121_electrode_config_t
+{
+    uint8_t bv; /* baseline value */
+    uint8_t tth; /* touch threshold */
+    uint8_t rth; /* release threshold */
+    uint8_t cdc; /* charge current (optional if auto-conf) */
+    uint8_t cdt; /* charge time (optional if auto-conf) */
+    int gpio; /* gpio config */
+};
+
+struct mpr121_baseline_filter_config_t
+{
+    uint8_t mhd; /* max half delta (except for touched) */
+    uint8_t nhd; /* noise half delta */
+    uint8_t ncl; /* noise count limit */
+    uint8_t fdl; /* filter delay count limit */
+};
+
+struct mpr121_baseline_filters_config_t
+{
+    struct mpr121_baseline_filter_config_t rising;
+    struct mpr121_baseline_filter_config_t falling;
+    struct mpr121_baseline_filter_config_t touched;
+};
+
+struct mpr121_debounce_config_t
+{
+    uint8_t dt; /* debounce count for touch */
+    uint8_t dr; /* debounce count for release */
+};
+
+/* first filter iterations */
+#define FFI_6_SAMPLES   0
+#define FFI_10_SAMPLES  1
+#define FFI_18_SAMPLES  2
+#define FFI_34_SAMPLES  3
+/* charge discharge current */
+#define CDC_DISABLE     0
+#define CDC_uA(ua)      (ua)
+/* charge discharge time */
+#define CDT_DISABLE     0
+#define CDT_log_us(lus) (lus) /* actual value = 2^{us-2} µs */
+/* second filter iterations */
+#define SFI_4_SAMPLES   0
+#define SFI_6_SAMPLES   1
+#define SFI_10_SAMPLES  2
+#define SFI_18_SAMPLES  3
+/* Eletrode sample interval */
+#define ESI_log_ms(lms) (lms) /* actual value = 2^{lms} ms */
+
+struct mpr121_global_config_t
+{
+    uint8_t ffi; /* first filter iterations */
+    uint8_t cdc; /* global charge discharge current */
+    uint8_t cdt; /* global charge discharge time */
+    uint8_t sfi; /* second first iterations */
+    uint8_t esi; /* electrode sample interval */
+};
+
+#define RETRY_NEVER     0
+#define RETRY_2_TIMES   1
+#define RETRY_4_TIMES   2
+#define RETRY_8_TIMES   3
+
+struct mpr121_auto_config_t
+{
+    bool en; /* auto-conf enable */
+    bool ren; /* auto-reconf enable */
+    uint8_t retry; /* retry count */
+    bool scts; /* skip charge time search */
+    uint8_t usl; /* upper-side limit */
+    uint8_t lsl; /* lower-side limit */
+    uint8_t tl; /* target level */
+    bool acfie; /* auto-conf fail interrupt en */
+    bool arfie; /* auto-reconf fail interrupt en */
+    bool oorie; /* out of range interrupt en */
+};
+
+/* electrode mode */
+#define ELE_DISABLE     0
+#define ELE_EN0_x(x)    ((x) + 1)
+/* eleprox mode */
+#define ELEPROX_DISABLE 0
+#define ELEPROX_EN0_1   1
+#define ELEPROX_EN0_3   2
+#define ELEPROX_EN0_11  3
+/* calibration lock */
+#define CL_SLOW_TRACK   0
+#define CL_DISABLE      1
+#define CL_TRACK        2
+#define CL_FAST_TRACK   3
+
+struct mpr121_config_t
+{
+    struct mpr121_electrode_config_t ele[ELECTRODE_COUNT];
+    struct mpr121_electrode_config_t eleprox;
+    struct
+    {
+        struct mpr121_baseline_filters_config_t ele;
+        struct mpr121_baseline_filters_config_t eleprox;
+    }filters;
+    struct mpr121_debounce_config_t debounce;
+    struct mpr121_global_config_t global;
+    struct mpr121_auto_config_t autoconf;
+    uint8_t ele_en; /* eletroce mode */
+    uint8_t eleprox_en; /* proximity mode */
+    uint8_t cal_lock; /* calibration lock */
+};
+
+/* gpio value */
+#define ELE_GPIO_CLR    0
+#define ELE_GPIO_SET    1
+#define ELE_GPIO_TOG    2
+/* pwm value */
+#define ELE_PWM_DISABLE 0
+#define ELE_PWM_DUTY(x) (x)
+#define ELE_PWM_MIN_DUTY    1
+#define ELE_PWM_MAX_DUTY    15
+
+void mpr121_init(void);
+void mpr121_set_config(struct mpr121_config_t *conf);
+/* gpios are only implemented for electrode>=4, use ELE_GPIO_* for value */
+void mpr121_set_gpio_output(int ele, int gpio_val);
+/* pwm value is between 0 and 15, use ELE_PWM_DISABLE or ELE_PWM_DUTY */
+void mpr121_set_gpio_pwm(int ele, int pwm);
+/* get electrode status (bitmap)
+ * NOTE this function merely returns the last electrode status read from the
+ * device and does not actively ask the device for touch status. */
+unsigned mpr121_get_touch_status(void);
+
+#endif /* __MPR121_ZENXFI3_H__ */