diff options
| author | Jarkko Nikula <jarkko.nikula@linux.intel.com> | 2025-08-22 13:56:27 +0300 |
|---|---|---|
| committer | Alexandre Belloni <alexandre.belloni@bootlin.com> | 2025-09-16 17:06:42 +0200 |
| commit | f8d9e56aeb87ce82ce8636cd176cc59b69aa0e41 (patch) | |
| tree | 0fce5617c0062bdd7e64a0ab3e00408e9d900feb /include/linux | |
| parent | d515503f3c8a8475b2f78782534aad09722904e1 (diff) | |
i3c: master: Add helpers for DMA mapping and bounce buffer handling
Some I3C controllers such as MIPI I3C HCI may pad the last DWORD (32-bit)
with stale data from the RX FIFO in DMA transfers if the receive length
is not DWORD aligned and when the device DMA is IOMMU mapped.
In such a case, a properly sized bounce buffer is required in order to
avoid possible data corruption. In a review discussion, proposal was to
have a common helpers in I3C core for DMA mapping and bounce buffer
handling.
Drivers may use the helper i3c_master_dma_map_single() to map a buffer
for a DMA transfer. It internally allocates a bounce buffer if buffer is
not DMA'able or when the driver requires it for a transfer.
Helper i3c_master_dma_unmap_single() does the needed cleanups and
data copying from the bounce buffer.
Signed-off-by: Jarkko Nikula <jarkko.nikula@linux.intel.com>
Reviewed-by: Frank Li <Frank.Li@nxp.com>
Link: https://lore.kernel.org/r/20250822105630.2820009-2-jarkko.nikula@linux.intel.com
Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>
Diffstat (limited to 'include/linux')
| -rw-r--r-- | include/linux/i3c/master.h | 26 |
1 files changed, 26 insertions, 0 deletions
diff --git a/include/linux/i3c/master.h b/include/linux/i3c/master.h index 043f5c7ff398..c52a82dd79a6 100644 --- a/include/linux/i3c/master.h +++ b/include/linux/i3c/master.h @@ -558,6 +558,26 @@ struct i3c_master_controller { #define i3c_bus_for_each_i3cdev(bus, dev) \ list_for_each_entry(dev, &(bus)->devs.i3c, common.node) +/** + * struct i3c_dma - DMA transfer and mapping descriptor + * @dev: device object of a device doing DMA + * @buf: destination/source buffer for DMA + * @len: length of transfer + * @map_len: length of DMA mapping + * @addr: mapped DMA address for a Host Controller Driver + * @dir: DMA direction + * @bounce_buf: an allocated bounce buffer if transfer needs it or NULL + */ +struct i3c_dma { + struct device *dev; + void *buf; + size_t len; + size_t map_len; + dma_addr_t addr; + enum dma_data_direction dir; + void *bounce_buf; +}; + int i3c_master_do_i2c_xfers(struct i3c_master_controller *master, const struct i2c_msg *xfers, int nxfers); @@ -575,6 +595,12 @@ int i3c_master_get_free_addr(struct i3c_master_controller *master, int i3c_master_add_i3c_dev_locked(struct i3c_master_controller *master, u8 addr); int i3c_master_do_daa(struct i3c_master_controller *master); +struct i3c_dma *i3c_master_dma_map_single(struct device *dev, void *ptr, + size_t len, bool force_bounce, + enum dma_data_direction dir); +void i3c_master_dma_unmap_single(struct i3c_dma *dma_xfer); +DEFINE_FREE(i3c_master_dma_unmap_single, void *, + if (_T) i3c_master_dma_unmap_single(_T)) int i3c_master_set_info(struct i3c_master_controller *master, const struct i3c_device_info *info); |