src/cyw43_ctrl: Rework roam/interference config to use ioctl helpers

Reimplement the WiFi roaming and interference-mitigation configuration
in terms of cyw43_ioctl() instead of dedicated low-level (cyw43_ll_*)
functions, per maintainer feedback on PR #146. This keeps the footprint
small: only the generic u32 ioctl helpers cost binary space, while the
per-feature wrappers are static inline and the named-iovar helpers are
the only additional functions.

Add public helpers:

  - cyw43_ioctl_set_u32() / cyw43_ioctl_get_u32()
    Wrap cyw43_ioctl() for the common case of a 4-byte ioctl value.

Add CYW43_IOCTL_xxx constants (encoded as (WLC_cmd << 1) | is_set, the
same scheme as the existing CYW43_IOCTL_ defines):

  - GET/SET_ROAM_TRIGGER, GET/SET_ROAM_DELTA, GET/SET_ROAM_SCAN_PERIOD
  - GET/SET_INTERFERENCE_MODE

Roaming/interference API (behaviour unchanged from PR #146; the bytes
sent to the chip are identical, only the call path differs):

  - cyw43_wifi_set_roam_params() / cyw43_wifi_get_roam_params()
    static inline, built on the u32 ioctl helpers.
  - cyw43_wifi_set_interference_mode() / cyw43_wifi_get_interference_mode()
    static inline, built on the u32 ioctl helpers.
  - cyw43_wifi_set_roam_enabled() / cyw43_wifi_get_roam_enabled()
    Toggle/read the "roam_off" iovar via WLC_SET_VAR / WLC_GET_VAR.

Remove the cyw43_ll_wifi_{set,get}_roam_* and
cyw43_ll_wifi_{set,get}_interference_mode low-level functions and their
WLC_* defines, which are no longer needed.

function order

Author: mitchellcairns

src/cyw43.h

@@ -107,8 +107,8 @@
 /*!
  * \name Interference mitigation mode
  * \anchor CYW43_IFMODE_
- * \see cyw43_wifi_interference_mode_set() to set the mitigation mode
- * \see cyw43_wifi_interference_mode_get() to get the mitigation mode
+ * \see cyw43_wifi_set_interference_mode() to set the mitigation mode
+ * \see cyw43_wifi_get_interference_mode() to get the mitigation mode
  */
 //!\{
 #define CYW43_IFMODE_NONE         (0)     ///< None/Disabled
@@ -200,6 +200,34 @@ void cyw43_deinit(cyw43_t *self);
  */
 int cyw43_ioctl(cyw43_t *self, uint32_t cmd, size_t len, uint8_t *buf, uint32_t iface);
 
+/*!
+ * \brief Set an ioctl whose value is a single unsigned 32-bit integer
+ *
+ * Convenience wrapper around \ref cyw43_ioctl for the common case of an ioctl
+ * that takes a 4-byte value, e.g. the various \c CYW43_IOCTL_SET_xxx commands.
+ *
+ * \param self  the driver state object. This should always be \c &cyw43_state
+ * \param cmd   the ioctl command to send, e.g. one of the \c CYW43_IOCTL_SET_xxx defines
+ * \param val   the value to set
+ * \param iface the interface to use, either \ref CYW43_ITF_STA or \ref CYW43_ITF_AP
+ * \return 0 on success, negative error code on failure
+ */
+int cyw43_ioctl_set_u32(cyw43_t *self, uint32_t cmd, uint32_t val, uint32_t iface);
+
+/*!
+ * \brief Get an ioctl whose value is a single unsigned 32-bit integer
+ *
+ * Convenience wrapper around \ref cyw43_ioctl for the common case of an ioctl
+ * that returns a 4-byte value, e.g. the various \c CYW43_IOCTL_GET_xxx commands.
+ *
+ * \param self    the driver state object. This should always be \c &cyw43_state
+ * \param cmd     the ioctl command to send, e.g. one of the \c CYW43_IOCTL_GET_xxx defines
+ * \param out_val Output: the value that was read. May be NULL.
+ * \param iface   the interface to use, either \ref CYW43_ITF_STA or \ref CYW43_ITF_AP
+ * \return 0 on success, negative error code on failure
+ */
+int cyw43_ioctl_get_u32(cyw43_t *self, uint32_t cmd, uint32_t *out_val, uint32_t iface);
+
 /*!
  * \brief Send a raw ethernet packet
  *
@@ -228,7 +256,9 @@ int cyw43_send_ethernet(cyw43_t *self, int itf, size_t len, const void *buf, boo
  * \param mode  Interference mitigation mode, one of \ref CYW43_IFMODE_
  * \return 0 on success, negative error code on failure
  */
-int cyw43_wifi_set_interference_mode(cyw43_t *self, uint32_t mode);
+static inline int cyw43_wifi_set_interference_mode(cyw43_t *self, uint32_t mode) {
+    return cyw43_ioctl_set_u32(self, CYW43_IOCTL_SET_INTERFERENCE_MODE, mode, CYW43_ITF_STA);
+}
 
 /*!
  * \brief Get the current WiFi interference mitigation mode
@@ -237,7 +267,9 @@ int cyw43_wifi_set_interference_mode(cyw43_t *self, uint32_t mode);
  * \param mode  Output: current interference mitigation mode, one of \ref CYW43_IFMODE_
  * \return 0 on success, negative error code on failure
  */
-int cyw43_wifi_get_interference_mode(cyw43_t *self, uint32_t *mode);
+static inline int cyw43_wifi_get_interference_mode(cyw43_t *self, uint32_t *mode) {
+    return cyw43_ioctl_get_u32(self, CYW43_IOCTL_GET_INTERFERENCE_MODE, mode, CYW43_ITF_STA);
+}
 
 /*!
  * \brief Set the wifi power management mode
@@ -414,6 +446,17 @@ int cyw43_wifi_leave(cyw43_t *self, int itf);
  */
 int cyw43_wifi_set_roam_enabled(cyw43_t *self, bool enabled);
 
+/*!
+ * \brief Query whether WiFi roaming is enabled on the STA interface
+ *
+ * Reads back the current state of the \c roam_off iovar.
+ *
+ * \param self     The driver state object, always \c &cyw43_state
+ * \param enabled  Output: true if roaming is enabled, false if disabled
+ * \return 0 on success, negative error code on failure
+ */
+int cyw43_wifi_get_roam_enabled(cyw43_t *self, bool *enabled);
+
 /*!
  * \brief Configure WiFi roaming parameters for the STA interface
  *
@@ -437,7 +480,17 @@ int cyw43_wifi_set_roam_enabled(cyw43_t *self, bool enabled);
  *                      APs while below the trigger threshold.
  * \return 0 on success, negative error code on failure
  */
-int cyw43_wifi_set_roam_params(cyw43_t *self, int trigger_dbm, int candidate_delta_db, int scan_period_ms);
+static inline int cyw43_wifi_set_roam_params(cyw43_t *self, int trigger_dbm, int candidate_delta_db, int scan_period_ms) {
+    int ret = cyw43_ioctl_set_u32(self, CYW43_IOCTL_SET_ROAM_TRIGGER, (uint32_t)trigger_dbm, CYW43_ITF_STA);
+    if (ret) {
+        return ret;
+    }
+    ret = cyw43_ioctl_set_u32(self, CYW43_IOCTL_SET_ROAM_DELTA, (uint32_t)candidate_delta_db, CYW43_ITF_STA);
+    if (ret) {
+        return ret;
+    }
+    return cyw43_ioctl_set_u32(self, CYW43_IOCTL_SET_ROAM_SCAN_PERIOD, (uint32_t)scan_period_ms, CYW43_ITF_STA);
+}
 
 /*!
  * \brief Retrieve the current WiFi roaming parameters for the STA interface
@@ -454,7 +507,32 @@ int cyw43_wifi_set_roam_params(cyw43_t *self, int trigger_dbm, int candidate_del
  *                            for better APs while below the trigger threshold.
  * \return 0 on success, negative error code on failure
  */
-int cyw43_wifi_get_roam_params(cyw43_t *self, int *trigger_dbm, int *candidate_delta_db, int *scan_period_ms);
+static inline int cyw43_wifi_get_roam_params(cyw43_t *self, int *trigger_dbm, int *candidate_delta_db, int *scan_period_ms) {
+    uint32_t val;
+    int ret;
+    if (trigger_dbm != NULL) {
+        ret = cyw43_ioctl_get_u32(self, CYW43_IOCTL_GET_ROAM_TRIGGER, &val, CYW43_ITF_STA);
+        if (ret) {
+            return ret;
+        }
+        *trigger_dbm = (int)(int32_t)val;
+    }
+    if (candidate_delta_db != NULL) {
+        ret = cyw43_ioctl_get_u32(self, CYW43_IOCTL_GET_ROAM_DELTA, &val, CYW43_ITF_STA);
+        if (ret) {
+            return ret;
+        }
+        *candidate_delta_db = (int)(int32_t)val;
+    }
+    if (scan_period_ms != NULL) {
+        ret = cyw43_ioctl_get_u32(self, CYW43_IOCTL_GET_ROAM_SCAN_PERIOD, &val, CYW43_ITF_STA);
+        if (ret) {
+            return ret;
+        }
+        *scan_period_ms = (int)(int32_t)val;
+    }
+    return 0;
+}
 
 /*!
  * \brief Get the signal strength (RSSI) of the wifi network

src/cyw43_ctrl.c

@@ -455,6 +455,22 @@ int cyw43_ioctl(cyw43_t *self, uint32_t cmd, size_t len, uint8_t *buf, uint32_t
     return ret;
 }
 
+int cyw43_ioctl_set_u32(cyw43_t *self, uint32_t cmd, uint32_t val, uint32_t iface) {
+    // The wire format is little-endian; RP2 hosts are little-endian so the
+    // value can be passed straight through (matching cyw43_wifi_get_rssi()).
+    uint32_t buf = val;
+    return cyw43_ioctl(self, cmd, sizeof(buf), (uint8_t *)&buf, iface);
+}
+
+int cyw43_ioctl_get_u32(cyw43_t *self, uint32_t cmd, uint32_t *out_val, uint32_t iface) {
+    uint32_t buf = 0;
+    int ret = cyw43_ioctl(self, cmd, sizeof(buf), (uint8_t *)&buf, iface);
+    if (ret == 0 && out_val != NULL) {
+        *out_val = buf;
+    }
+    return ret;
+}
+
 int cyw43_send_ethernet(cyw43_t *self, int itf, size_t len, const void *buf, bool is_pbuf) {
     CYW43_THREAD_ENTER;
     int ret = cyw43_ensure_up(self);
@@ -491,41 +507,6 @@ static int cyw43_wifi_on(cyw43_t *self, uint32_t country) {
     return ret;
 }
 
-int cyw43_wifi_set_interference_mode(cyw43_t *self, uint32_t mode)
-{
-    CYW43_THREAD_ENTER;
-    int ret = cyw43_ensure_up(self);
-    if (ret) {
-        CYW43_THREAD_EXIT;
-        return ret;
-    }
-
-    ret = cyw43_ll_wifi_set_interference_mode(&self->cyw43_ll, mode);
-
-    CYW43_THREAD_EXIT;
-    return ret;
-}
-
-int cyw43_wifi_get_interference_mode(cyw43_t *self, uint32_t *mode)
-{
-    CYW43_THREAD_ENTER;
-    if (!mode) {
-        CYW43_THREAD_EXIT;
-        return -CYW43_EINVAL;
-    }
-
-    int ret = cyw43_ensure_up(self);
-    if (ret) {
-        CYW43_THREAD_EXIT;
-        return ret;
-    }
-
-    ret = cyw43_ll_wifi_get_interference_mode(&self->cyw43_ll, mode);
-
-    CYW43_THREAD_EXIT;
-    return ret;
-}
-
 int cyw43_wifi_pm(cyw43_t *self, uint32_t pm_in) {
     CYW43_THREAD_ENTER;
     int ret = cyw43_ensure_up(self);
@@ -703,63 +684,44 @@ int cyw43_wifi_leave(cyw43_t *self, int itf) {
     return cyw43_ioctl(self, CYW43_IOCTL_SET_DISASSOC, 0, NULL, itf);
 }
 
-int cyw43_wifi_set_roam_enabled(cyw43_t *self, bool enabled)
-{
-    CYW43_THREAD_ENTER;
-    if (!CYW43_STA_IS_ACTIVE(self)) {
-        CYW43_THREAD_EXIT;
-        return -CYW43_EPERM;
-    }
-
-    int ret = cyw43_ensure_up(self);
-    if (ret) {
-        CYW43_THREAD_EXIT;
-        return ret;
-    }
-
-    ret = cyw43_ll_wifi_set_roam_enabled(&self->cyw43_ll, enabled);
-
-    CYW43_THREAD_EXIT;
-    return ret;
-}
-
-int cyw43_wifi_set_roam_params(cyw43_t *self, int trigger_dbm, int candidate_delta_db, int scan_period_ms)
-{
-    CYW43_THREAD_ENTER;
-    if (!CYW43_STA_IS_ACTIVE(self)) {
-        CYW43_THREAD_EXIT;
-        return -CYW43_EPERM;
-    }
-
-    int ret = cyw43_ensure_up(self);
-    if (ret) {
-        CYW43_THREAD_EXIT;
-        return ret;
-    }
-
-    ret = cyw43_ll_wifi_set_roam_params(&self->cyw43_ll, trigger_dbm, candidate_delta_db, scan_period_ms);
-
-    CYW43_THREAD_EXIT;
-    return ret;
-}
-
-int cyw43_wifi_get_roam_params(cyw43_t *self, int *trigger_dbm, int *candidate_delta_db, int *scan_period_ms)
-{
-    CYW43_THREAD_ENTER;
-    if (!CYW43_STA_IS_ACTIVE(self)) {
-        CYW43_THREAD_EXIT;
-        return -CYW43_EPERM;
+int cyw43_wifi_set_roam_enabled(cyw43_t *self, bool enabled) {
+    // "roam_off" is a string-named iovar rather than a numbered ioctl, so it is
+    // sent via the WLC_SET_VAR ioctl with a "<name>\0<le32 value>" payload.
+    static const char var[] = "roam_off";
+    const size_t name_len = sizeof(var); // includes the NUL terminator
+    uint8_t buf[sizeof(var) + 4];
+    memcpy(buf, var, name_len);
+    // roam_off == 1 disables roaming, 0 enables it. Only the low byte is
+    // significant; store little-endian byte-wise to avoid unaligned access.
+    buf[name_len + 0] = enabled ? 0 : 1;
+    buf[name_len + 1] = 0;
+    buf[name_len + 2] = 0;
+    buf[name_len + 3] = 0;
+    return cyw43_ioctl(self, CYW43_IOCTL_SET_VAR, name_len + 4, buf, CYW43_ITF_STA);
+}
+
+int cyw43_wifi_get_roam_enabled(cyw43_t *self, bool *enabled) {
+    if (enabled == NULL) {
+        return -CYW43_EINVAL;
     }
-
-    int ret = cyw43_ensure_up(self);
-    if (ret) {
-        CYW43_THREAD_EXIT;
-        return ret;
+    // Read the "roam_off" iovar back via the WLC_GET_VAR ioctl. The variable
+    // name is written into the buffer and the firmware replaces it with the
+    // little-endian u32 value on return (see how CYW43_IOCTL_GET_VAR is used).
+    static const char var[] = "roam_off";
+    const size_t name_len = sizeof(var); // includes the NUL terminator
+    uint8_t buf[sizeof(var) + 4];
+    memcpy(buf, var, name_len);
+    buf[name_len + 0] = 0;
+    buf[name_len + 1] = 0;
+    buf[name_len + 2] = 0;
+    buf[name_len + 3] = 0;
+    int ret = cyw43_ioctl(self, CYW43_IOCTL_GET_VAR, name_len + 4, buf, CYW43_ITF_STA);
+    if (ret == 0) {
+        uint32_t roam_off = (uint32_t)buf[0] | ((uint32_t)buf[1] << 8) |
+            ((uint32_t)buf[2] << 16) | ((uint32_t)buf[3] << 24);
+        // roam_off != 0 means roaming is disabled.
+        *enabled = (roam_off == 0);
     }
-
-    ret = cyw43_ll_wifi_get_roam_params(&self->cyw43_ll, trigger_dbm, candidate_delta_db, scan_period_ms);
-
-    CYW43_THREAD_EXIT;
     return ret;
 }