iio: Add buffer enable/disable callbacks

This patch adds a enable and disable callback that is called when the
buffer is enabled/disabled. This can be used by buffer implementations that
need to do some setup or teardown work. E.g. a DMA based buffer can use
this to start/stop the DMA transfer.

Signed-off-by: Lars-Peter Clausen <lars@metafoo.de>
Signed-off-by: Jonathan Cameron <jic23@kernel.org>

diff --git a/drivers/iio/industrialio-buffer.c b/drivers/iio/industrialio-buffer.c
index 98a6447..a4b164a 100644 (file)
--- a/drivers/iio/industrialio-buffer.c
+++ b/drivers/iio/industrialio-buffer.c
@@ -568,6 +568,22 @@ static void iio_buffer_deactivate_all(struct iio_dev *indio_dev)
                iio_buffer_deactivate(buffer);
 }
 
+static int iio_buffer_enable(struct iio_buffer *buffer,
+       struct iio_dev *indio_dev)
+{
+       if (!buffer->access->enable)
+               return 0;
+       return buffer->access->enable(buffer, indio_dev);
+}
+
+static int iio_buffer_disable(struct iio_buffer *buffer,
+       struct iio_dev *indio_dev)
+{
+       if (!buffer->access->disable)
+               return 0;
+       return buffer->access->disable(buffer, indio_dev);
+}
+
 static void iio_buffer_update_bytes_per_datum(struct iio_dev *indio_dev,
        struct iio_buffer *buffer)
 {
@@ -719,6 +735,7 @@ static int iio_verify_update(struct iio_dev *indio_dev,
 static int iio_enable_buffers(struct iio_dev *indio_dev,
        struct iio_device_config *config)
 {
+       struct iio_buffer *buffer;
        int ret;
 
        indio_dev->active_scan_mask = config->scan_mask;
@@ -753,6 +770,12 @@ static int iio_enable_buffers(struct iio_dev *indio_dev,
                indio_dev->info->hwfifo_set_watermark(indio_dev,
                        config->watermark);
 
+       list_for_each_entry(buffer, &indio_dev->buffer_list, buffer_list) {
+               ret = iio_buffer_enable(buffer, indio_dev);
+               if (ret)
+                       goto err_disable_buffers;
+       }
+
        indio_dev->currentmode = config->mode;
 
        if (indio_dev->setup_ops->postenable) {
@@ -760,12 +783,16 @@ static int iio_enable_buffers(struct iio_dev *indio_dev,
                if (ret) {
                        dev_dbg(&indio_dev->dev,
                               "Buffer not started: postenable failed (%d)\n", ret);
-                       goto err_run_postdisable;
+                       goto err_disable_buffers;
                }
        }
 
        return 0;
 
+err_disable_buffers:
+       list_for_each_entry_continue_reverse(buffer, &indio_dev->buffer_list,
+                                            buffer_list)
+               iio_buffer_disable(buffer, indio_dev);
 err_run_postdisable:
        indio_dev->currentmode = INDIO_DIRECT_MODE;
        if (indio_dev->setup_ops->postdisable)
@@ -778,6 +805,7 @@ err_undo_config:
 
 static int iio_disable_buffers(struct iio_dev *indio_dev)
 {
+       struct iio_buffer *buffer;
        int ret = 0;
        int ret2;
 
@@ -798,6 +826,12 @@ static int iio_disable_buffers(struct iio_dev *indio_dev)
                        ret = ret2;
        }
 
+       list_for_each_entry(buffer, &indio_dev->buffer_list, buffer_list) {
+               ret2 = iio_buffer_disable(buffer, indio_dev);
+               if (ret2 && !ret)
+                       ret = ret2;
+       }
+
        indio_dev->currentmode = INDIO_DIRECT_MODE;
 
        if (indio_dev->setup_ops->postdisable) {

diff --git a/include/linux/iio/buffer.h b/include/linux/iio/buffer.h
index 4d99a53..2ec3ad5 100644 (file)
--- a/include/linux/iio/buffer.h
+++ b/include/linux/iio/buffer.h
@@ -33,6 +33,11 @@ struct iio_buffer;
  *                     storage.
  * @set_bytes_per_datum:set number of bytes per datum
  * @set_length:                set number of datums in buffer
+ * @enable:             called if the buffer is attached to a device and the
+ *                      device starts sampling. Calls are balanced with
+ *                      @disable.
+ * @disable:            called if the buffer is attached to a device and the
+ *                      device stops sampling. Calles are balanced with @enable.
  * @release:           called when the last reference to the buffer is dropped,
  *                     should free all resources allocated by the buffer.
  * @modes:             Supported operating modes by this buffer type
@@ -58,6 +63,9 @@ struct iio_buffer_access_funcs {
        int (*set_bytes_per_datum)(struct iio_buffer *buffer, size_t bpd);
        int (*set_length)(struct iio_buffer *buffer, int length);
 
+       int (*enable)(struct iio_buffer *buffer, struct iio_dev *indio_dev);
+       int (*disable)(struct iio_buffer *buffer, struct iio_dev *indio_dev);
+
        void (*release)(struct iio_buffer *buffer);
 
        unsigned int modes;