[PATCH V2][1/4] mmc: solve DMA boundary limitation of CQHCI driver

[Jyan Chou]

Due to synopsys data book's description, it had a limitation
while using DMA that buffer size and start address must not
exceed 128 MB.

We add an option setup_tran_desc to make tran_desc setting flexible.

Signed-off-by: Jyan Chou <jyanchou@xxxxxxxxxxx>

---
v0 -> v1:
- Separate different patch supports into single patch.

v1 -> v2:
- Export cqhci_set_tran_desc for setting the descriptor's callback function.
---
---
 drivers/mmc/host/cqhci-core.c | 8 +++++++-
 drivers/mmc/host/cqhci.h      | 2 ++
 2 files changed, 9 insertions(+), 1 deletion(-)

diff --git a/drivers/mmc/host/cqhci-core.c b/drivers/mmc/host/cqhci-core.c
index b3d7d6d8d654..5560329d2a7d 100644
--- a/drivers/mmc/host/cqhci-core.c
+++ b/drivers/mmc/host/cqhci-core.c
@@ -474,7 +474,7 @@ static int cqhci_dma_map(struct mmc_host *host, struct mmc_request *mrq)
 	return sg_count;
 }
 
-static void cqhci_set_tran_desc(u8 *desc, dma_addr_t addr, int len, bool end,
+void cqhci_set_tran_desc(u8 *desc, dma_addr_t addr, int len, bool end,
 				bool dma64)
 {
 	__le32 *attr = (__le32 __force *)desc;
@@ -495,6 +495,7 @@ static void cqhci_set_tran_desc(u8 *desc, dma_addr_t addr, int len, bool end,
 		dataddr[0] = cpu_to_le32(addr);
 	}
 }
+EXPORT_SYMBOL(cqhci_set_tran_desc);
 
 static int cqhci_prep_tran_desc(struct mmc_request *mrq,
 			       struct cqhci_host *cq_host, int tag)
@@ -516,6 +517,11 @@ static int cqhci_prep_tran_desc(struct mmc_request *mrq,
 
 	desc = get_trans_desc(cq_host, tag);
 
+	if (cq_host->ops->setup_tran_desc) {
+		cq_host->ops->setup_tran_desc(data, cq_host, desc, sg_count);
+		return 0;
+	}
+
 	for_each_sg(data->sg, sg, sg_count, i) {
 		addr = sg_dma_address(sg);
 		len = sg_dma_len(sg);
diff --git a/drivers/mmc/host/cqhci.h b/drivers/mmc/host/cqhci.h
index 1a12e40a02e6..cb3dfb161c54 100644
--- a/drivers/mmc/host/cqhci.h
+++ b/drivers/mmc/host/cqhci.h
@@ -289,6 +289,8 @@ struct cqhci_host_ops {
 				 u64 *data);
 	void (*pre_enable)(struct mmc_host *mmc);
 	void (*post_disable)(struct mmc_host *mmc);
+	void (*setup_tran_desc)(struct mmc_data *data,
+		struct cqhci_host *cq_host, u8 *desc, int sg_count);
 #ifdef CONFIG_MMC_CRYPTO
 	int (*program_key)(struct cqhci_host *cq_host,
 			   const union cqhci_crypto_cfg_entry *cfg, int slot);
-- 
2.42.0