#define TPACPI_DBG_HKEY                0x0008
 #define TPACPI_DBG_FAN         0x0010
 #define TPACPI_DBG_BRGHT       0x0020
+#define TPACPI_DBG_MIXER       0x0040
 
 #define onoff(status, bit) ((status) & (1 << (bit)) ? "on" : "off")
 #define enabled(status, bit) ((status) & (1 << (bit)) ? "enabled" : "disabled")
  * Volume subdriver
  */
 
-static int volume_offset = 0x30;
+/*
+ * IBM ThinkPads have a simple volume controller with MUTE gating.
+ * Very early Lenovo ThinkPads follow the IBM ThinkPad spec.
+ *
+ * Since the *61 series (and probably also the later *60 series), Lenovo
+ * ThinkPads only implement the MUTE gate.
+ *
+ * EC register 0x30
+ *   Bit 6: MUTE (1 mutes sound)
+ *   Bit 3-0: Volume
+ *   Other bits should be zero as far as we know.
+ *
+ * This is also stored in CMOS NVRAM, byte 0x60, bit 6 (MUTE), and
+ * bits 3-0 (volume).  Other bits in NVRAM may have other functions,
+ * such as bit 7 which is used to detect repeated presses of MUTE,
+ * and we leave them unchanged.
+ */
+
+enum {
+       TP_EC_AUDIO = 0x30,
+
+       /* TP_EC_AUDIO bits */
+       TP_EC_AUDIO_MUTESW = 6,
+
+       /* TP_EC_AUDIO bitmasks */
+       TP_EC_AUDIO_LVL_MSK = 0x0F,
+       TP_EC_AUDIO_MUTESW_MSK = (1 << TP_EC_AUDIO_MUTESW),
+
+       /* Maximum volume */
+       TP_EC_VOLUME_MAX = 14,
+};
+
+enum tpacpi_volume_access_mode {
+       TPACPI_VOL_MODE_AUTO = 0,       /* Not implemented yet */
+       TPACPI_VOL_MODE_EC,             /* Pure EC control */
+       TPACPI_VOL_MODE_UCMS_STEP,      /* UCMS step-based control: N/A */
+       TPACPI_VOL_MODE_ECNVRAM,        /* EC control w/ NVRAM store */
+       TPACPI_VOL_MODE_MAX
+};
+
+static enum tpacpi_volume_access_mode volume_mode =
+       TPACPI_VOL_MODE_MAX;
+
+
+/*
+ * Used to syncronize writers to TP_EC_AUDIO and
+ * TP_NVRAM_ADDR_MIXER, as we need to do read-modify-write
+ */
+static struct mutex volume_mutex;
+
+static void tpacpi_volume_checkpoint_nvram(void)
+{
+       u8 lec = 0;
+       u8 b_nvram;
+       const u8 ec_mask = TP_EC_AUDIO_LVL_MSK | TP_EC_AUDIO_MUTESW_MSK;
+
+       if (volume_mode != TPACPI_VOL_MODE_ECNVRAM)
+               return;
+
+       vdbg_printk(TPACPI_DBG_MIXER,
+               "trying to checkpoint mixer state to NVRAM...\n");
+
+       if (mutex_lock_killable(&volume_mutex) < 0)
+               return;
+
+       if (unlikely(!acpi_ec_read(TP_EC_AUDIO, &lec)))
+               goto unlock;
+       lec &= ec_mask;
+       b_nvram = nvram_read_byte(TP_NVRAM_ADDR_MIXER);
+
+       if (lec != (b_nvram & ec_mask)) {
+               /* NVRAM needs update */
+               b_nvram &= ~ec_mask;
+               b_nvram |= lec;
+               nvram_write_byte(b_nvram, TP_NVRAM_ADDR_MIXER);
+               dbg_printk(TPACPI_DBG_MIXER,
+                          "updated NVRAM mixer status to 0x%02x (0x%02x)\n",
+                          (unsigned int) lec, (unsigned int) b_nvram);
+       } else {
+               vdbg_printk(TPACPI_DBG_MIXER,
+                          "NVRAM mixer status already is 0x%02x (0x%02x)\n",
+                          (unsigned int) lec, (unsigned int) b_nvram);
+       }
+
+unlock:
+       mutex_unlock(&volume_mutex);
+}
+
+static int volume_get_status_ec(u8 *status)
+{
+       u8 s;
+
+       if (!acpi_ec_read(TP_EC_AUDIO, &s))
+               return -EIO;
+
+       *status = s;
+
+       dbg_printk(TPACPI_DBG_MIXER, "status 0x%02x\n", s);
+
+       return 0;
+}
+
+static int volume_get_status(u8 *status)
+{
+       return volume_get_status_ec(status);
+}
+
+static int volume_set_status_ec(const u8 status)
+{
+       if (!acpi_ec_write(TP_EC_AUDIO, status))
+               return -EIO;
+
+       dbg_printk(TPACPI_DBG_MIXER, "set EC mixer to 0x%02x\n", status);
+
+       return 0;
+}
+
+static int volume_set_status(const u8 status)
+{
+       return volume_set_status_ec(status);
+}
+
+static int volume_set_mute_ec(const bool mute)
+{
+       int rc;
+       u8 s, n;
+
+       if (mutex_lock_killable(&volume_mutex) < 0)
+               return -EINTR;
+
+       rc = volume_get_status_ec(&s);
+       if (rc)
+               goto unlock;
+
+       n = (mute) ? s | TP_EC_AUDIO_MUTESW_MSK :
+                    s & ~TP_EC_AUDIO_MUTESW_MSK;
+
+       if (n != s)
+               rc = volume_set_status_ec(n);
+
+unlock:
+       mutex_unlock(&volume_mutex);
+       return rc;
+}
+
+static int volume_set_mute(const bool mute)
+{
+       dbg_printk(TPACPI_DBG_MIXER, "trying to %smute\n",
+                  (mute) ? "" : "un");
+       return volume_set_mute_ec(mute);
+}
+
+static int volume_set_volume_ec(const u8 vol)
+{
+       int rc;
+       u8 s, n;
+
+       if (vol > TP_EC_VOLUME_MAX)
+               return -EINVAL;
+
+       if (mutex_lock_killable(&volume_mutex) < 0)
+               return -EINTR;
+
+       rc = volume_get_status_ec(&s);
+       if (rc)
+               goto unlock;
+
+       n = (s & ~TP_EC_AUDIO_LVL_MSK) | vol;
+
+       if (n != s)
+               rc = volume_set_status_ec(n);
+
+unlock:
+       mutex_unlock(&volume_mutex);
+       return rc;
+}
+
+static int volume_set_volume(const u8 vol)
+{
+       dbg_printk(TPACPI_DBG_MIXER,
+                  "trying to set volume level to %hu\n", vol);
+       return volume_set_volume_ec(vol);
+}
+
+static void volume_suspend(pm_message_t state)
+{
+       tpacpi_volume_checkpoint_nvram();
+}
+
+static void volume_shutdown(void)
+{
+       tpacpi_volume_checkpoint_nvram();
+}
+
+static void volume_exit(void)
+{
+       tpacpi_volume_checkpoint_nvram();
+}
+
+static int __init volume_init(struct ibm_init_struct *iibm)
+{
+       vdbg_printk(TPACPI_DBG_INIT, "initializing volume subdriver\n");
+
+       mutex_init(&volume_mutex);
+
+       /*
+        * Check for module parameter bogosity, note that we
+        * init volume_mode to TPACPI_VOL_MODE_MAX in order to be
+        * able to detect "unspecified"
+        */
+       if (volume_mode > TPACPI_VOL_MODE_MAX)
+               return -EINVAL;
+
+       if (volume_mode == TPACPI_VOL_MODE_UCMS_STEP) {
+               printk(TPACPI_ERR
+                       "UCMS step volume mode not implemented, "
+                       "please contact %s\n", TPACPI_MAIL);
+               return 1;
+       }
+
+       if (volume_mode == TPACPI_VOL_MODE_AUTO ||
+           volume_mode == TPACPI_VOL_MODE_MAX) {
+               volume_mode = TPACPI_VOL_MODE_ECNVRAM;
+
+               dbg_printk(TPACPI_DBG_INIT | TPACPI_DBG_MIXER,
+                               "driver auto-selected volume_mode=%d\n",
+                               volume_mode);
+       } else {
+               dbg_printk(TPACPI_DBG_INIT | TPACPI_DBG_MIXER,
+                               "using user-supplied volume_mode=%d\n",
+                               volume_mode);
+       }
+
+       vdbg_printk(TPACPI_DBG_INIT | TPACPI_DBG_MIXER,
+                       "volume is supported\n");
+
+       return 0;
+}
 
 static int volume_read(char *p)
 {
        int len = 0;
-       u8 level;
+       u8 status;
 
-       if (!acpi_ec_read(volume_offset, &level)) {
+       if (volume_get_status(&status) < 0) {
                len += sprintf(p + len, "level:\t\tunreadable\n");
        } else {
-               len += sprintf(p + len, "level:\t\t%d\n", level & 0xf);
-               len += sprintf(p + len, "mute:\t\t%s\n", onoff(level, 6));
+               len += sprintf(p + len, "level:\t\t%d\n",
+                               status & TP_EC_AUDIO_LVL_MSK);
+               len += sprintf(p + len, "mute:\t\t%s\n",
+                               onoff(status, TP_EC_AUDIO_MUTESW));
                len += sprintf(p + len, "commands:\tup, down, mute\n");
                len += sprintf(p + len, "commands:\tlevel <level>"
-                              " (<level> is 0-15)\n");
+                              " (<level> is 0-%d)\n", TP_EC_VOLUME_MAX);
        }
 
        return len;
 
 static int volume_write(char *buf)
 {
-       int cmos_cmd, inc, i;
-       u8 level, mute;
-       int new_level, new_mute;
+       u8 s;
+       u8 new_level, new_mute;
+       int l;
        char *cmd;
+       int rc;
 
-       while ((cmd = next_cmd(&buf))) {
-               if (!acpi_ec_read(volume_offset, &level))
-                       return -EIO;
-               new_mute = mute = level & 0x40;
-               new_level = level = level & 0xf;
+       rc = volume_get_status(&s);
+       if (rc < 0)
+               return rc;
 
+       new_level = s & TP_EC_AUDIO_LVL_MSK;
+       new_mute  = s & TP_EC_AUDIO_MUTESW_MSK;
+
+       while ((cmd = next_cmd(&buf))) {
                if (strlencmp(cmd, "up") == 0) {
-                       if (mute)
+                       if (new_mute)
                                new_mute = 0;
-                       else
-                               new_level = level == 15 ? 15 : level + 1;
+                       else if (new_level < TP_EC_VOLUME_MAX)
+                               new_level++;
                } else if (strlencmp(cmd, "down") == 0) {
-                       if (mute)
+                       if (new_mute)
                                new_mute = 0;
-                       else
-                               new_level = level == 0 ? 0 : level - 1;
-               } else if (sscanf(cmd, "level %d", &new_level) == 1 &&
-                          new_level >= 0 && new_level <= 15) {
-                       /* new_level set */
+                       else if (new_level > 0)
+                               new_level--;
+               } else if (sscanf(cmd, "level %u", &l) == 1 &&
+                          l >= 0 && l <= TP_EC_VOLUME_MAX) {
+                               new_level = l;
                } else if (strlencmp(cmd, "mute") == 0) {
-                       new_mute = 0x40;
+                       new_mute = TP_EC_AUDIO_MUTESW_MSK;
                } else
                        return -EINVAL;
+       }
 
-               if (new_level != level) {
-                       /* mute doesn't change */
-
-                       cmos_cmd = (new_level > level) ?
-                                       TP_CMOS_VOLUME_UP : TP_CMOS_VOLUME_DOWN;
-                       inc = new_level > level ? 1 : -1;
-
-                       if (mute && (issue_thinkpad_cmos_command(cmos_cmd) ||
-                                    !acpi_ec_write(volume_offset, level)))
-                               return -EIO;
-
-                       for (i = level; i != new_level; i += inc)
-                               if (issue_thinkpad_cmos_command(cmos_cmd) ||
-                                   !acpi_ec_write(volume_offset, i + inc))
-                                       return -EIO;
-
-                       if (mute &&
-                           (issue_thinkpad_cmos_command(TP_CMOS_VOLUME_MUTE) ||
-                            !acpi_ec_write(volume_offset, new_level + mute))) {
-                               return -EIO;
-                       }
-               }
-
-               if (new_mute != mute) {
-                       /* level doesn't change */
+       tpacpi_disclose_usertask("procfs volume",
+                               "%smute and set level to %d\n",
+                               new_mute ? "" : "un", new_level);
 
-                       cmos_cmd = (new_mute) ?
-                                  TP_CMOS_VOLUME_MUTE : TP_CMOS_VOLUME_UP;
+       rc = volume_set_status(new_mute | new_level);
 
-                       if (issue_thinkpad_cmos_command(cmos_cmd) ||
-                           !acpi_ec_write(volume_offset, level + new_mute))
-                               return -EIO;
-               }
-       }
-
-       return 0;
+       return (rc == -EINTR) ? -ERESTARTSYS : rc;
 }
 
 static struct ibm_struct volume_driver_data = {
        .name = "volume",
        .read = volume_read,
        .write = volume_write,
+       .exit = volume_exit,
+       .suspend = volume_suspend,
+       .shutdown = volume_shutdown,
 };
 
 /*************************************************************************
                .data = &brightness_driver_data,
        },
        {
+               .init = volume_init,
                .data = &volume_driver_data,
        },
        {
                 "used for backwards compatibility with userspace, "
                 "see documentation");
 
+module_param_named(volume_mode, volume_mode, uint, 0444);
+MODULE_PARM_DESC(volume_mode,
+                "Selects volume control strategy: "
+                "0=auto, 1=EC, 2=N/A, 3=EC+NVRAM");
+
 #define TPACPI_PARAM(feature) \
        module_param_call(feature, set_ibm_param, NULL, NULL, 0); \
        MODULE_PARM_DESC(feature, "Simulates thinkpad-acpi procfs command " \