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-rw-r--r--include/linux/stm.h13
1 files changed, 13 insertions, 0 deletions
diff --git a/include/linux/stm.h b/include/linux/stm.h
index 9d0083d364e6..8369d8a8cabd 100644
--- a/include/linux/stm.h
+++ b/include/linux/stm.h
@@ -50,6 +50,8 @@ struct stm_device;
* @sw_end: last STP master available to software
* @sw_nchannels: number of STP channels per master
* @sw_mmiosz: size of one channel's IO space, for mmap, optional
+ * @hw_override: masters in the STP stream will not match the ones
+ * assigned by software, but are up to the STM hardware
* @packet: callback that sends an STP packet
* @mmio_addr: mmap callback, optional
* @link: called when a new stm_source gets linked to us, optional
@@ -67,6 +69,16 @@ struct stm_device;
* description. That is, the lowest master that can be allocated to software
* writers is @sw_start and data from this writer will appear is @sw_start
* master in the STP stream.
+ *
+ * The @packet callback should adhere to the following rules:
+ * 1) it must return the number of bytes it consumed from the payload;
+ * 2) therefore, if it sent a packet that does not have payload (like FLAG),
+ * it must return zero;
+ * 3) if it does not support the requested packet type/flag combination,
+ * it must return -ENOTSUPP.
+ *
+ * The @unlink callback is called when there are no more active writers so
+ * that the master/channel can be quiesced.
*/
struct stm_data {
const char *name;
@@ -75,6 +87,7 @@ struct stm_data {
unsigned int sw_end;
unsigned int sw_nchannels;
unsigned int sw_mmiosz;
+ unsigned int hw_override;
ssize_t (*packet)(struct stm_data *, unsigned int,
unsigned int, unsigned int,
unsigned int, unsigned int,