Fixed MTP to work with TWRP

drivers/iio/kfifo_buf.c

@@ -0,0 +1,192 @@
+#include <linux/slab.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/device.h>
+#include <linux/workqueue.h>
+#include <linux/kfifo.h>
+#include <linux/mutex.h>
+#include <linux/iio/kfifo_buf.h>
+#include <linux/sched.h>
+#include <linux/poll.h>
+
+struct iio_kfifo {
+	struct iio_buffer buffer;
+	struct kfifo kf;
+	struct mutex user_lock;
+	int update_needed;
+};
+
+#define iio_to_kfifo(r) container_of(r, struct iio_kfifo, buffer)
+
+static inline int __iio_allocate_kfifo(struct iio_kfifo *buf,
+				int bytes_per_datum, int length)
+{
+	if ((length == 0) || (bytes_per_datum == 0))
+		return -EINVAL;
+
+	return __kfifo_alloc((struct __kfifo *)&buf->kf, length,
+			     bytes_per_datum, GFP_KERNEL);
+}
+
+static int iio_request_update_kfifo(struct iio_buffer *r)
+{
+	int ret = 0;
+	struct iio_kfifo *buf = iio_to_kfifo(r);
+
+	mutex_lock(&buf->user_lock);
+	if (buf->update_needed) {
+		kfifo_free(&buf->kf);
+		ret = __iio_allocate_kfifo(buf, buf->buffer.bytes_per_datum,
+				   buf->buffer.length);
+		buf->update_needed = false;
+	} else {
+		kfifo_reset_out(&buf->kf);
+	}
+	mutex_unlock(&buf->user_lock);
+
+	return ret;
+}
+
+static int iio_get_length_kfifo(struct iio_buffer *r)
+{
+	return r->length;
+}
+
+static IIO_BUFFER_ENABLE_ATTR;
+static IIO_BUFFER_LENGTH_ATTR;
+
+static struct attribute *iio_kfifo_attributes[] = {
+	&dev_attr_length.attr,
+	&dev_attr_enable.attr,
+	NULL,
+};
+
+static struct attribute_group iio_kfifo_attribute_group = {
+	.attrs = iio_kfifo_attributes,
+	.name = "buffer",
+};
+
+static int iio_get_bytes_per_datum_kfifo(struct iio_buffer *r)
+{
+	return r->bytes_per_datum;
+}
+
+static int iio_mark_update_needed_kfifo(struct iio_buffer *r)
+{
+	struct iio_kfifo *kf = iio_to_kfifo(r);
+	kf->update_needed = true;
+	return 0;
+}
+
+static int iio_set_bytes_per_datum_kfifo(struct iio_buffer *r, size_t bpd)
+{
+	if (r->bytes_per_datum != bpd) {
+		r->bytes_per_datum = bpd;
+		iio_mark_update_needed_kfifo(r);
+	}
+	return 0;
+}
+
+static int iio_set_length_kfifo(struct iio_buffer *r, int length)
+{
+	/* Avoid an invalid state */
+	if (length < 2)
+		length = 2;
+	if (r->length != length) {
+		r->length = length;
+		iio_mark_update_needed_kfifo(r);
+	}
+	return 0;
+}
+
+static int iio_store_to_kfifo(struct iio_buffer *r,
+			      const void *data)
+{
+	int ret;
+	struct iio_kfifo *kf = iio_to_kfifo(r);
+	ret = kfifo_in(&kf->kf, data, 1);
+	if (ret != 1)
+		return -EBUSY;
+
+	wake_up_interruptible_poll(&r->pollq, POLLIN | POLLRDNORM);
+
+	return 0;
+}
+
+static int iio_read_first_n_kfifo(struct iio_buffer *r,
+			   size_t n, char __user *buf)
+{
+	int ret, copied;
+	struct iio_kfifo *kf = iio_to_kfifo(r);
+
+	if (mutex_lock_interruptible(&kf->user_lock))
+		return -ERESTARTSYS;
+
+	if (!kfifo_initialized(&kf->kf) || n < kfifo_esize(&kf->kf))
+		ret = -EINVAL;
+	else
+		ret = kfifo_to_user(&kf->kf, buf, n, &copied);
+	mutex_unlock(&kf->user_lock);
+	if (ret < 0)
+		return ret;
+
+	return copied;
+}
+
+static bool iio_kfifo_buf_data_available(struct iio_buffer *r)
+{
+	struct iio_kfifo *kf = iio_to_kfifo(r);
+	bool empty;
+
+	mutex_lock(&kf->user_lock);
+	empty = kfifo_is_empty(&kf->kf);
+	mutex_unlock(&kf->user_lock);
+
+	return !empty;
+}
+
+static void iio_kfifo_buffer_release(struct iio_buffer *buffer)
+{
+	struct iio_kfifo *kf = iio_to_kfifo(buffer);
+
+	mutex_destroy(&kf->user_lock);
+	kfifo_free(&kf->kf);
+	kfree(kf);
+}
+
+static const struct iio_buffer_access_funcs kfifo_access_funcs = {
+	.store_to = &iio_store_to_kfifo,
+	.read_first_n = &iio_read_first_n_kfifo,
+	.data_available = iio_kfifo_buf_data_available,
+	.request_update = &iio_request_update_kfifo,
+	.get_bytes_per_datum = &iio_get_bytes_per_datum_kfifo,
+	.set_bytes_per_datum = &iio_set_bytes_per_datum_kfifo,
+	.get_length = &iio_get_length_kfifo,
+	.set_length = &iio_set_length_kfifo,
+	.release = &iio_kfifo_buffer_release,
+};
+
+struct iio_buffer *iio_kfifo_allocate(struct iio_dev *indio_dev)
+{
+	struct iio_kfifo *kf;
+
+	kf = kzalloc(sizeof *kf, GFP_KERNEL);
+	if (!kf)
+		return NULL;
+	kf->update_needed = true;
+	iio_buffer_init(&kf->buffer);
+	kf->buffer.attrs = &iio_kfifo_attribute_group;
+	kf->buffer.access = &kfifo_access_funcs;
+	kf->buffer.length = 2;
+	mutex_init(&kf->user_lock);
+	return &kf->buffer;
+}
+EXPORT_SYMBOL(iio_kfifo_allocate);
+
+void iio_kfifo_free(struct iio_buffer *r)
+{
+	iio_buffer_put(r);
+}
+EXPORT_SYMBOL(iio_kfifo_free);
+
+MODULE_LICENSE("GPL");