mmc: tegra: use bounce buffer APIs

Tegra's MMC driver does DMA, and hence needs cache-aligned buffers. In
some cases (e.g. user load commands) this cannot be guaranteed by callers
of the MMC APIs. To solve this, modify the Tegra MMC driver to use the
new bounce_buffer_*() APIs.

Note: Ideally, all U-Boot code will always provide address- and size-
aligned buffers, so a bounce buffer will only ever be needed for user-
supplied buffers (e.g. load commands). Ensuring this removes the need
for performance-sucking bounce buffer cache management and memcpy()s.
The one known exception at present is the SCR buffer in sd_change_freq(),
which is only 8 bytes long. Solving this requires enhancing struct
mmc_data to know the difference between buffer size and transferred data
size, or forcing all callers of mmc_send_cmd() to have allocated buffers
using ALLOC_CACHE_ALIGN_BUFFER(), which while true in this case, is not
enforced in any way at present, and so cannot be assumed by the core MMC
code.

Signed-off-by: Stephen Warren <swarren@nvidia.com>
Acked-by: Simon Glass <sjg@chromium.org>
Tested-by: Simon Glass <sjg@chromium.org>
Signed-off-by: Andy Fleming <afleming@freescale.com>

diff --git a/drivers/mmc/tegra_mmc.c b/drivers/mmc/tegra_mmc.c
index 8fea6a6bfb2cc0a9aa7c85c1b191e1972612233c..b141eafc7bb16ae0cdeeb704068b92b1e15a4983 100644 (file)
--- a/drivers/mmc/tegra_mmc.c
+++ b/drivers/mmc/tegra_mmc.c
@@ -19,6 +19,7 @@
  * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
  */
 
+#include <bouncebuf.h>
 #include <common.h>
 #include <asm/gpio.h>
 #include <asm/io.h>
@@ -66,14 +67,17 @@ static void tegra_get_setup(struct mmc_host *host, int dev_index)
        host->reg = (struct tegra_mmc *)host->base;
 }
 
-static void mmc_prepare_data(struct mmc_host *host, struct mmc_data *data)
+static void mmc_prepare_data(struct mmc_host *host, struct mmc_data *data,
+                               struct bounce_buffer *bbstate)
 {
        unsigned char ctrl;
 
-       debug("data->dest: %08X, data->blocks: %u, data->blocksize: %u\n",
-       (u32)data->dest, data->blocks, data->blocksize);
 
-       writel((u32)data->dest, &host->reg->sysad);
+       debug("buf: %p (%p), data->blocks: %u, data->blocksize: %u\n",
+               bbstate->bounce_buffer, bbstate->user_buffer, data->blocks,
+               data->blocksize);
+
+       writel((u32)bbstate->bounce_buffer, &host->reg->sysad);
        /*
         * DMASEL[4:3]
         * 00 = Selects SDMA
@@ -114,14 +118,6 @@ static void mmc_set_transfer_mode(struct mmc_host *host, struct mmc_data *data)
        if (data->flags & MMC_DATA_READ)
                mode |= TEGRA_MMC_TRNMOD_DATA_XFER_DIR_SEL_READ;
 
-       if (data->flags & MMC_DATA_WRITE) {
-               if ((uintptr_t)data->src & (ARCH_DMA_MINALIGN - 1))
-                       printf("Warning: unaligned write to %p may fail\n",
-                              data->src);
-               flush_dcache_range((ulong)data->src, (ulong)data->src +
-                       data->blocks * data->blocksize);
-       }
-
        writew(mode, &host->reg->trnmod);
 }
 
@@ -156,8 +152,8 @@ static int mmc_wait_inhibit(struct mmc_host *host,
        return 0;
 }
 
-static int mmc_send_cmd(struct mmc *mmc, struct mmc_cmd *cmd,
-                       struct mmc_data *data)
+static int mmc_send_cmd_bounced(struct mmc *mmc, struct mmc_cmd *cmd,
+                       struct mmc_data *data, struct bounce_buffer *bbstate)
 {
        struct mmc_host *host = (struct mmc_host *)mmc->priv;
        int flags, i;
@@ -172,7 +168,7 @@ static int mmc_send_cmd(struct mmc *mmc, struct mmc_cmd *cmd,
                return result;
 
        if (data)
-               mmc_prepare_data(host, data);
+               mmc_prepare_data(host, data, bbstate);
 
        debug("cmd->arg: %08x\n", cmd->cmdarg);
        writel(cmd->cmdarg, &host->reg->argument);
@@ -322,20 +318,42 @@ static int mmc_send_cmd(struct mmc *mmc, struct mmc_cmd *cmd,
                        }
                }
                writel(mask, &host->reg->norintsts);
-               if (data->flags & MMC_DATA_READ) {
-                       if ((uintptr_t)data->dest & (ARCH_DMA_MINALIGN - 1))
-                               printf("Warning: unaligned read from %p "
-                                       "may fail\n", data->dest);
-                       invalidate_dcache_range((ulong)data->dest,
-                               (ulong)data->dest +
-                                       data->blocks * data->blocksize);
-               }
        }
 
        udelay(1000);
        return 0;
 }
 
+static int mmc_send_cmd(struct mmc *mmc, struct mmc_cmd *cmd,
+                       struct mmc_data *data)
+{
+       void *buf;
+       unsigned int bbflags;
+       size_t len;
+       struct bounce_buffer bbstate;
+       int ret;
+
+       if (data) {
+               if (data->flags & MMC_DATA_READ) {
+                       buf = data->dest;
+                       bbflags = GEN_BB_WRITE;
+               } else {
+                       buf = (void *)data->src;
+                       bbflags = GEN_BB_READ;
+               }
+               len = data->blocks * data->blocksize;
+
+               bounce_buffer_start(&bbstate, buf, len, bbflags);
+       }
+
+       ret = mmc_send_cmd_bounced(mmc, cmd, data, &bbstate);
+
+       if (data)
+               bounce_buffer_stop(&bbstate);
+
+       return ret;
+}
+
 static void mmc_change_clock(struct mmc_host *host, uint clock)
 {
        int div;

diff --git a/include/configs/tegra20-common.h b/include/configs/tegra20-common.h
index 31b68be4dbef81014cc193705962fdc2507871f8..5c0833a4d8ccfa32e4a893d5d05d337e426e6557 100644 (file)
--- a/include/configs/tegra20-common.h
+++ b/include/configs/tegra20-common.h
@@ -202,4 +202,7 @@
 #define CONFIG_SYS_NAND_SELF_INIT
 #define CONFIG_SYS_NAND_ONFI_DETECTION
 
+/* Misc utility code */
+#define CONFIG_BOUNCE_BUFFER
+
 #endif /* __TEGRA20_COMMON_H */