spi: core: added spi_resource management
SPI resource management framework used while processing a spi_message
via the spi-core.
The basic idea is taken from devres, but as the allocation may happen
fairly frequently, some provisioning (in the form of an unused spi_device
pointer argument to spi_res_alloc) has been made so that at a later stage
we may implement reuse objects allocated earlier avoiding the repeated
allocation by keeping a cache of objects that we can reuse.
This framework can get used for:
* rewriting spi_messages
* to fullfill alignment requirements of the spi_master HW
* to fullfill transfer length requirements
(e.g: transfers need to be less than 64k)
* consolidate spi_messages with multiple transfers into a single transfer
when the total transfer length is below a threshold.
* reimplement spi_unmap_buf without explicitly needing to check if it has
been mapped
Signed-off-by: Martin Sperl <kernel@martin.sperl.org>
Signed-off-by: Mark Brown <broonie@kernel.org>
diff --git a/include/linux/spi/spi.h b/include/linux/spi/spi.h
index 53be3a4..38204b5 100644
--- a/include/linux/spi/spi.h
+++ b/include/linux/spi/spi.h
@@ -582,6 +582,37 @@
extern struct spi_master *spi_busnum_to_master(u16 busnum);
+/*
+ * SPI resource management while processing a SPI message
+ */
+
+/**
+ * struct spi_res - spi resource management structure
+ * @entry: list entry
+ * @release: release code called prior to freeing this resource
+ * @data: extra data allocated for the specific use-case
+ *
+ * this is based on ideas from devres, but focused on life-cycle
+ * management during spi_message processing
+ */
+typedef void (*spi_res_release_t)(struct spi_master *master,
+ struct spi_message *msg,
+ void *res);
+struct spi_res {
+ struct list_head entry;
+ spi_res_release_t release;
+ unsigned long long data[]; /* guarantee ull alignment */
+};
+
+extern void *spi_res_alloc(struct spi_device *spi,
+ spi_res_release_t release,
+ size_t size, gfp_t gfp);
+extern void spi_res_add(struct spi_message *message, void *res);
+extern void spi_res_free(void *res);
+
+extern void spi_res_release(struct spi_master *master,
+ struct spi_message *message);
+
/*---------------------------------------------------------------------------*/
/*
@@ -720,6 +751,7 @@
* @status: zero for success, else negative errno
* @queue: for use by whichever driver currently owns the message
* @state: for use by whichever driver currently owns the message
+ * @resources: for resource management when the spi message is processed
*
* A @spi_message is used to execute an atomic sequence of data transfers,
* each represented by a struct spi_transfer. The sequence is "atomic"
@@ -766,11 +798,15 @@
*/
struct list_head queue;
void *state;
+
+ /* list of spi_res reources when the spi message is processed */
+ struct list_head resources;
};
static inline void spi_message_init_no_memset(struct spi_message *m)
{
INIT_LIST_HEAD(&m->transfers);
+ INIT_LIST_HEAD(&m->resources);
}
static inline void spi_message_init(struct spi_message *m)