CHROMIUM: Input: atmel_mxt_ts - refactor mxt_object_show

 * use scnprintf() like all well-behaved sysfs entries
 * conserve limited (PAGE_SIZE) sysfs output buffer space by not printing
   the object's index which is not that useful to userspace

Signed-off-by: Daniel Kurtz <djkurtz@chromium.org>
BUG=chromium-os:27713
TEST=cat /sys/bus/i2c/drivers/atmel_mxt_ts/2-004b/object

Change-Id: Iefd6ebd058efbd7131ffbfff0db3762e3273dddf
Reviewed-on: https://gerrit.chromium.org/gerrit/20601
Reviewed-by: Benson Leung <bleung@chromium.org>
Commit-Ready: Daniel Kurtz <djkurtz@chromium.org>
Reviewed-by: Daniel Kurtz <djkurtz@chromium.org>
Tested-by: Daniel Kurtz <djkurtz@chromium.org>

diff --git a/drivers/input/touchscreen/atmel_mxt_ts.c b/drivers/input/touchscreen/atmel_mxt_ts.c
index 83bc438..c3a8530 100644 (file)
--- a/drivers/input/touchscreen/atmel_mxt_ts.c
+++ b/drivers/input/touchscreen/atmel_mxt_ts.c
@@ -990,46 +990,44 @@ static ssize_t mxt_object_show(struct device *dev,
 {
        struct mxt_data *data = dev_get_drvdata(dev);
        int count = 0;
-       int i, j, k;
-       int error;
+       size_t i, j, k;
+       int error = 0;
+       u8 *obuf = NULL;
 
-       for (i = 0; i < data->info.object_num; i++) {
+       for (i = 0; i < data->info.object_num && count < PAGE_SIZE - 1; i++) {
                struct mxt_object *object = &data->object_table[i];
 
                if (!mxt_object_readable(object->type))
                        continue;
 
-               for (j = 0; j < object->instances; j++) {
-                       u8 obuf[object->size];
+               count += scnprintf(&buf[count], PAGE_SIZE - count,
+                                  "\nType: %u\n", object->type);
 
-                       count += snprintf(buf + count, PAGE_SIZE - count,
-                                         "Object[%d] Type: T%d Instance: %d/%d\n",
-                                         i + 1, object->type, j + 1,
-                                         object->instances);
-                       if (count >= PAGE_SIZE)
-                               return PAGE_SIZE - 1;
+               obuf = krealloc(obuf, object->size, GFP_KERNEL);
+               if (!obuf)
+                       return -ENOMEM;
 
+               for (j = 0; j < object->instances; j++) {
+                       if (object->instances > 1)
+                               count += scnprintf(&buf[count],
+                                                  PAGE_SIZE - count,
+                                                  "Instance: %zu\n", j);
 
                        error = mxt_read_object(data, object, j, obuf);
                        if (error)
-                               return error;
-
-                       for (k = 0; k < object->size; k++) {
-                               count += snprintf(buf + count,
-                                                 PAGE_SIZE - count,
-                                                 "\t[%2d]: %02x (%d)\n",
-                                                 k, obuf[k], obuf[k]);
-                               if (count >= PAGE_SIZE)
-                                       return PAGE_SIZE - 1;
-                       }
-
-                       count += snprintf(buf + count, PAGE_SIZE - count, "\n");
-                       if (count >= PAGE_SIZE)
-                               return PAGE_SIZE - 1;
+                               goto free_obuf;
+
+                       for (k = 0; k < object->size; k++)
+                               count += scnprintf(&buf[count],
+                                                  PAGE_SIZE - count,
+                                                  "\t[%2zu]: %02x (%d)\n",
+                                                  k, obuf[k], obuf[k]);
                }
        }
 
-       return count;
+free_obuf:
+       kfree(obuf);
+       return error ?: count;
 }
 
 static ssize_t mxt_object_store(struct device *dev,