[v6,1/4] mmc: API for accessing host supported maximum segment count and size

Commit Message

Xinming Hu Dec. 19, 2017, 12:06 p.m. UTC

sdio device drivers need be able to get the host supported max_segs
and max_seg_size, so that they know the buffer size to allocate while
utilizing the scatter/gather DMA buffer list.

This patch provides API for this purpose.

Signed-off-by: Xinming Hu <[e-mail]>
Signed-off-by: Amitkumar Karwar <[e-mail]>
---
v2: v2 was submitted with minor improvement like replacing BUG_ON() with WARN_ON()
v3: Addressed below review comments from Ulf Hansson
    a) In v3, patch has been split into two separate patches.
    b) Patch 1/2 introduces an API to fetch max_seg_size and max_segs
    c) Replaced WARN_ON() with proper error code when sg_ptr->length is invalid
    d) Instead of duplicating the code in mmc_io_rw_extended(), extra bool parameter
       has been added to this function and used it in new APIs for SG.
v4: Removed WARN_ON() calls in newly added APIs. It's gets called in probe handler.
    Caller already takes care of it(Shawn Lin).
v5: Rebased on latest code base.
v6: Split driver caller to separate patch.
---
 drivers/mmc/core/sdio_io.c    | 21 +++++++++++++++++++++
 include/linux/mmc/sdio_func.h |  3 +++
 2 files changed, 24 insertions(+)

Patch

diff --git a/drivers/mmc/core/sdio_io.c b/drivers/mmc/core/sdio_io.c
index d40744b..4806521 100644
--- a/drivers/mmc/core/sdio_io.c
+++ b/drivers/mmc/core/sdio_io.c
@@ -725,3 +725,24 @@  int sdio_set_host_pm_flags(struct sdio_func *func, mmc_pm_flag_t flags)
 	return 0;
 }
 EXPORT_SYMBOL_GPL(sdio_set_host_pm_flags);
+
+/**
+ *	sdio_get_host_max_seg_size - get host maximum segment size
+ *	@func: SDIO function attached to host
+ */
+unsigned int sdio_get_host_max_seg_size(struct sdio_func *func)
+{
+	return func->card->host->max_seg_size;
+}
+EXPORT_SYMBOL_GPL(sdio_get_host_max_seg_size);
+
+/**
+ *	sdio_get_host_max_seg_count - get host maximum segment count
+ *	@func: SDIO function attached to host
+ */
+unsigned short sdio_get_host_max_seg_count(struct sdio_func *func)
+{
+	return func->card->host->max_segs;
+}
+EXPORT_SYMBOL_GPL(sdio_get_host_max_seg_count);
+
diff --git a/include/linux/mmc/sdio_func.h b/include/linux/mmc/sdio_func.h
index 97ca105..72d4de4 100644
--- a/include/linux/mmc/sdio_func.h
+++ b/include/linux/mmc/sdio_func.h
@@ -159,4 +159,7 @@  extern void sdio_f0_writeb(struct sdio_func *func, unsigned char b,
 extern mmc_pm_flag_t sdio_get_host_pm_caps(struct sdio_func *func);
 extern int sdio_set_host_pm_flags(struct sdio_func *func, mmc_pm_flag_t flags);
 
+unsigned short sdio_get_host_max_seg_count(struct sdio_func *func);
+unsigned int sdio_get_host_max_seg_size(struct sdio_func *func);
+
 #endif /* LINUX_MMC_SDIO_FUNC_H */