HID: uclogic: Return raw parameters from v2 pen init

Return the raw parameters buffer from uclogic_params_pen_init_v2(), if
requested, as a way to identify the tablet.

Signed-off-by: Nikolai Kondrashov <spbnick@gmail.com>
Signed-off-by: José Expósito <jose.exposito89@gmail.com>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>

diff --git a/drivers/hid/hid-uclogic-params.c b/drivers/hid/hid-uclogic-params.c
index 1d9168cc7dc01e84de73044111256fc76d132977..91379d7cd33e43c85b316fa4344d2ef6496675a9 100644 (file)
--- a/drivers/hid/hid-uclogic-params.c
+++ b/drivers/hid/hid-uclogic-params.c
@@ -338,28 +338,45 @@ static s32 uclogic_params_get_le24(const void *p)
  * uclogic_params_pen_init_v2() - initialize tablet interface pen
  * input and retrieve its parameters from the device, using v2 protocol.
  *
- * @pen:       Pointer to the pen parameters to initialize (to be
- *             cleaned up with uclogic_params_pen_cleanup()). Not modified in
- *             case of error, or if parameters are not found. Cannot be NULL.
- * @pfound:    Location for a flag which is set to true if the parameters
- *             were found, and to false if not (e.g. device was
- *             incompatible). Not modified in case of error. Cannot be NULL.
- * @hdev:      The HID device of the tablet interface to initialize and get
- *             parameters from. Cannot be NULL.
+ * @pen:               Pointer to the pen parameters to initialize (to be
+ *                     cleaned up with uclogic_params_pen_cleanup()). Not
+ *                     modified in case of error, or if parameters are not
+ *                     found. Cannot be NULL.
+ * @pfound:            Location for a flag which is set to true if the
+ *                     parameters were found, and to false if not (e.g.
+ *                     device was incompatible). Not modified in case of
+ *                     error. Cannot be NULL.
+ * @pparams_ptr:       Location for a kmalloc'ed pointer to the retrieved raw
+ *                     parameters, which could be used to identify the tablet
+ *                     to some extent. Should be freed with kfree after use.
+ *                     NULL, if not needed. Not modified in case of error.
+ *                     Only set if *pfound is set to true.
+ * @pparams_len:       Location for the length of the retrieved raw
+ *                     parameters. NULL, if not needed. Not modified in case
+ *                     of error. Only set if *pfound is set to true.
+ * @hdev:              The HID device of the tablet interface to initialize
+ *                     and get parameters from. Cannot be NULL.
  *
  * Returns:
  *     Zero, if successful. A negative errno code on error.
  */
 static int uclogic_params_pen_init_v2(struct uclogic_params_pen *pen,
                                        bool *pfound,
+                                       __u8 **pparams_ptr,
+                                       size_t *pparams_len,
                                        struct hid_device *hdev)
 {
        int rc;
        bool found = false;
-       /* Buffer for (part of) the string descriptor */
+       /* Buffer for (part of) the parameter string descriptor */
        __u8 *buf = NULL;
-       /* Descriptor length required */
-       const int len = 18;
+       /* Parameter string descriptor required length */
+       const int params_len_min = 18;
+       /* Parameter string descriptor accepted length */
+       const int params_len_max = 32;
+       /* Parameter string descriptor received length */
+       int params_len;
+       size_t i;
        s32 resolution;
        /* Pen report descriptor template parameters */
        s32 desc_params[UCLOGIC_RDESC_PEN_PH_ID_NUM];
@@ -377,7 +394,7 @@ static int uclogic_params_pen_init_v2(struct uclogic_params_pen *pen,
         * the Windows driver traffic.
         * NOTE: This enables fully-functional tablet mode.
         */
-       rc = uclogic_params_get_str_desc(&buf, hdev, 200, len);
+       rc = uclogic_params_get_str_desc(&buf, hdev, 200, params_len_max);
        if (rc == -EPIPE) {
                hid_dbg(hdev,
                        "string descriptor with pen parameters not found, assuming not compatible\n");
@@ -385,27 +402,28 @@ static int uclogic_params_pen_init_v2(struct uclogic_params_pen *pen,
        } else if (rc < 0) {
                hid_err(hdev, "failed retrieving pen parameters: %d\n", rc);
                goto cleanup;
-       } else if (rc != len) {
+       } else if (rc < params_len_min) {
                hid_dbg(hdev,
-                       "string descriptor with pen parameters has invalid length (got %d, expected %d), assuming not compatible\n",
-                       rc, len);
+                       "string descriptor with pen parameters is too short (got %d, expected at least %d), assuming not compatible\n",
+                       rc, params_len_min);
+               goto finish;
+       }
+
+       params_len = rc;
+
+       /*
+        * Check it's not just a catch-all UTF-16LE-encoded ASCII
+        * string (such as the model name) some tablets put into all
+        * unknown string descriptors.
+        */
+       for (i = 2;
+            i < params_len &&
+               (buf[i] >= 0x20 && buf[i] < 0x7f && buf[i + 1] == 0);
+            i += 2);
+       if (i >= params_len) {
+               hid_dbg(hdev,
+                       "string descriptor with pen parameters seems to contain only text, assuming not compatible\n");
                goto finish;
-       } else {
-               size_t i;
-               /*
-                * Check it's not just a catch-all UTF-16LE-encoded ASCII
-                * string (such as the model name) some tablets put into all
-                * unknown string descriptors.
-                */
-               for (i = 2;
-                    i < len &&
-                       (buf[i] >= 0x20 && buf[i] < 0x7f && buf[i + 1] == 0);
-                    i += 2);
-               if (i >= len) {
-                       hid_dbg(hdev,
-                               "string descriptor with pen parameters seems to contain only text, assuming not compatible\n");
-                       goto finish;
-               }
        }
 
        /*
@@ -429,8 +447,6 @@ static int uclogic_params_pen_init_v2(struct uclogic_params_pen *pen,
                        desc_params[UCLOGIC_RDESC_PEN_PH_ID_Y_LM] * 1000 /
                        resolution;
        }
-       kfree(buf);
-       buf = NULL;
 
        /*
         * Generate pen report descriptor
@@ -456,6 +472,13 @@ static int uclogic_params_pen_init_v2(struct uclogic_params_pen *pen,
        pen->fragmented_hires = true;
        pen->tilt_y_flipped = true;
        found = true;
+       if (pparams_ptr != NULL) {
+               *pparams_ptr = buf;
+               buf = NULL;
+       }
+       if (pparams_len != NULL)
+               *pparams_len = params_len;
+
 finish:
        *pfound = found;
        rc = 0;
@@ -828,7 +851,8 @@ static int uclogic_params_huion_init(struct uclogic_params *params,
                        "transition firmware detected, not probing pen v2 parameters\n");
        } else {
                /* Try to probe v2 pen parameters */
-               rc = uclogic_params_pen_init_v2(&p.pen, &found, hdev);
+               rc = uclogic_params_pen_init_v2(&p.pen, &found,
+                                               NULL, NULL, hdev);
                if (rc != 0) {
                        hid_err(hdev,
                                "failed probing pen v2 parameters: %d\n", rc);