[U-Boot] [PATCH v2] mmc/dwmmc: use bounce buffer for data exchange between CPU and MMC controller

[Alexey Brodkin]

Bounce buffer implementation takes care of proper data buffer alignemt
and correct flush/invalidation of data cache at once so we no longer
depend on input data variety and make sure CPU and MMC controller deal
with expected data in case of enabled data cache.

Bounce buffer requires to add its definition (CONFIG_BOUNCE_BUFFER) in
board configuration, otherwise corresponding library won't be compiled
and linker will fail to build resulting executable.

Difference since v1 - fixed compile-time warning with type casting to
"void *":
====
passing argument 2 of ‘bounce_buffer_start’ discards ‘const’ qualifier
from pointer target type
====

Signed-off-by: Alexey Brodkin <abrodkin at synopsys.com>

Cc: Mischa Jonker <mjonker at synopsys.com>
Cc: Alim Akhtar <alim.akhtar at samsung.com>
Cc: Rajeshwari Shinde <rajeshwari.s at samsung.com>
Cc: Jaehoon Chung <jh80.chung at samsung.com>
Cc: Amar <amarendra.xt at samsung.com>
Cc: Kyungmin Park <kyungmin.park at samsung.com>
Cc: Minkyu Kang <mk7.kang at samsung.com>
Cc: Simon Glass <sjg at chromium.org>
Cc: Pantelis Antoniou <panto at antoniou-consulting.com>
Cc: Andy Fleming <afleming at gmail.com>
---
 drivers/mmc/dw_mmc.c            | 32 ++++++++++++++++++++++----------
 include/configs/arndale.h       |  1 +
 include/configs/exynos5250-dt.h |  1 +
 3 files changed, 24 insertions(+), 10 deletions(-)

diff --git a/drivers/mmc/dw_mmc.c b/drivers/mmc/dw_mmc.c
index 19d9b0b..1e34f36 100644
--- a/drivers/mmc/dw_mmc.c
+++ b/drivers/mmc/dw_mmc.c
@@ -6,6 +6,7 @@
  * SPDX-License-Identifier:	GPL-2.0+
  */
 
+#include <bouncebuf.h>
 #include <common.h>
 #include <malloc.h>
 #include <mmc.h>
@@ -41,11 +42,13 @@ static void dwmci_set_idma_desc(struct dwmci_idmac *idmac,
 }
 
 static void dwmci_prepare_data(struct dwmci_host *host,
-		struct mmc_data *data, struct dwmci_idmac *cur_idmac)
+			       struct mmc_data *data,
+			       struct dwmci_idmac *cur_idmac,
+			       void *bounce_buffer)
 {
 	unsigned long ctrl;
 	unsigned int i = 0, flags, cnt, blk_cnt;
-	ulong data_start, data_end, start_addr;
+	ulong data_start, data_end;
 
 
 	blk_cnt = data->blocks;
@@ -55,11 +58,6 @@ static void dwmci_prepare_data(struct dwmci_host *host,
 	data_start = (ulong)cur_idmac;
 	dwmci_writel(host, DWMCI_DBADDR, (unsigned int)cur_idmac);
 
-	if (data->flags == MMC_DATA_READ)
-		start_addr = (unsigned int)data->dest;
-	else
-		start_addr = (unsigned int)data->src;
-
 	do {
 		flags = DWMCI_IDMAC_OWN | DWMCI_IDMAC_CH ;
 		flags |= (i == 0) ? DWMCI_IDMAC_FS : 0;
@@ -70,7 +68,7 @@ static void dwmci_prepare_data(struct dwmci_host *host,
 			cnt = data->blocksize * 8;
 
 		dwmci_set_idma_desc(cur_idmac, flags, cnt,
-				start_addr + (i * PAGE_SIZE));
+				    (u32)bounce_buffer + (i * PAGE_SIZE));
 
 		if (blk_cnt <= 8)
 			break;
@@ -117,6 +115,7 @@ static int dwmci_send_cmd(struct mmc *mmc, struct mmc_cmd *cmd,
 	u32 retry = 10000;
 	u32 mask, ctrl;
 	ulong start = get_timer(0);
+	struct bounce_buffer bbstate;
 
 	while (dwmci_readl(host, DWMCI_STATUS) & DWMCI_BUSY) {
 		if (get_timer(start) > timeout) {
@@ -127,8 +126,19 @@ static int dwmci_send_cmd(struct mmc *mmc, struct mmc_cmd *cmd,
 
 	dwmci_writel(host, DWMCI_RINTSTS, DWMCI_INTMSK_ALL);
 
-	if (data)
-		dwmci_prepare_data(host, data, cur_idmac);
+	if (data) {
+		if (data->flags == MMC_DATA_READ) {
+			bounce_buffer_start(&bbstate, (void*)data->dest,
+					    data->blocksize *
+					    data->blocks, GEN_BB_WRITE);
+		} else {
+			bounce_buffer_start(&bbstate, (void*)data->src,
+					    data->blocksize *
+					    data->blocks, GEN_BB_READ);
+		}
+		dwmci_prepare_data(host, data, cur_idmac,
+				   bbstate.bounce_buffer);
+	}
 
 	dwmci_writel(host, DWMCI_CMDARG, cmd->cmdarg);
 
@@ -204,6 +214,8 @@ static int dwmci_send_cmd(struct mmc *mmc, struct mmc_cmd *cmd,
 		ctrl = dwmci_readl(host, DWMCI_CTRL);
 		ctrl &= ~(DWMCI_DMA_EN);
 		dwmci_writel(host, DWMCI_CTRL, ctrl);
+
+		bounce_buffer_stop(&bbstate);
 	}
 
 	udelay(100);
diff --git a/include/configs/arndale.h b/include/configs/arndale.h
index a3cb56b..3d29caf 100644
--- a/include/configs/arndale.h
+++ b/include/configs/arndale.h
@@ -85,6 +85,7 @@
 #define CONFIG_DWMMC
 #define CONFIG_EXYNOS_DWMMC
 #define CONFIG_SUPPORT_EMMC_BOOT
+#define CONFIG_BOUNCE_BUFFER
 
 
 #define CONFIG_BOARD_EARLY_INIT_F
diff --git a/include/configs/exynos5250-dt.h b/include/configs/exynos5250-dt.h
index 8fb904c..b39bafc 100644
--- a/include/configs/exynos5250-dt.h
+++ b/include/configs/exynos5250-dt.h
@@ -102,6 +102,7 @@
 #define CONFIG_DWMMC
 #define CONFIG_EXYNOS_DWMMC
 #define CONFIG_SUPPORT_EMMC_BOOT
+#define CONFIG_BOUNCE_BUFFER
 
 
 #define CONFIG_BOARD_EARLY_INIT_F
-- 
1.8.4.2