Re: [PATCH] mmc: new API for data write using scatter gather DMA

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On 11/26/14 14:43, Ulf Hansson wrote:
On 26 November 2014 at 12:07, Avinash Patil<patila@xxxxxxxxxxx>  wrote:
From: Bing Zhao<bzhao@xxxxxxxxxxx>

This patch adds new API to handle scatter gather aggregation.

Why is this needed?

One thing I can imagine is that the receiving device has specific scatter-gather alignment requirements that are not covered in mmc_io_rw_extended(). So the new API does not so much handle scatter-gather, but leaves that up to the caller. Question is whether mmc_io_rw_extended() could be changed to accommodate those requirements instead of duplicating big part of it. Without knowing the exact requirements that is difficult to answer.

Regards,
Arend



Signed-off-by: Bing Zhao<bzhao@xxxxxxxxxxx>
Signed-off-by: Avinash Patil<patila@xxxxxxxxxxx>
Signed-off-by: Xinming Hu<huxm@xxxxxxxxxxx>
Signed-off-by: Cathy Luo<cluo@xxxxxxxxxxx>
---
  drivers/mmc/core/sdio_ops.c   | 65 +++++++++++++++++++++++++++++++++++++++++++
  include/linux/mmc/sdio_func.h |  5 ++++
  2 files changed, 70 insertions(+)

diff --git a/drivers/mmc/core/sdio_ops.c b/drivers/mmc/core/sdio_ops.c
index 62508b4..4c5e362 100644
--- a/drivers/mmc/core/sdio_ops.c
+++ b/drivers/mmc/core/sdio_ops.c
@@ -15,6 +15,7 @@
  #include<linux/mmc/card.h>
  #include<linux/mmc/mmc.h>
  #include<linux/mmc/sdio.h>
+#include<linux/export.h>

  #include "core.h"
  #include "sdio_ops.h"
@@ -204,6 +205,70 @@ int mmc_io_rw_extended(struct mmc_card *card, int write, unsigned fn,
         return 0;
  }

+int mmc_io_rw_extended_sg(struct mmc_card *card, int write, unsigned fn,
+                         unsigned addr, int incr_addr,
+                         struct sg_table *sgt, unsigned blksz)
+{
+       struct mmc_request mrq = {NULL};
+       struct mmc_command cmd = {0};
+       struct mmc_data data = {0};
+       struct scatterlist *sg_ptr;
+       unsigned blocks = 0;
+       int i;
+
+       BUG_ON(!card || !card->host);
+       BUG_ON(fn>  7);
+       BUG_ON(!blksz);

No BUG_ON() here please. Better to return an error.

+       for_each_sg(sgt->sgl, sg_ptr, sgt->nents, i) {
+               WARN_ON(sg_ptr->length>  card->host->max_seg_size);
+               blocks += DIV_ROUND_UP(sg_ptr->length, blksz);
+       }
+
+       /* sanity check */
+       if (addr&  ~0x1FFFF)
+               return -EINVAL;
+
+       mrq.cmd =&cmd;
+       mrq.data =&data;
+
+       cmd.opcode = SD_IO_RW_EXTENDED;
+       cmd.arg = write ? 0x80000000 : 0x00000000;
+       cmd.arg |= fn<<  28;
+       cmd.arg |= incr_addr ? 0x04000000 : 0x00000000;
+       cmd.arg |= addr<<  9;
+       cmd.arg |= 0x08000000 | blocks;
+       cmd.flags = MMC_RSP_SPI_R5 | MMC_RSP_R5 | MMC_CMD_ADTC;
+
+       data.blksz = blksz;
+       data.blocks = blocks;
+       data.flags = write ? MMC_DATA_WRITE : MMC_DATA_READ;
+
+       data.sg = sgt->sgl;
+       data.sg_len = sgt->nents;
+
+       mmc_set_data_timeout(&data, card);
+       mmc_wait_for_req(card->host,&mrq);
+
+       if (cmd.error)
+               return cmd.error;
+       if (data.error)
+               return data.error;
+
+       if (mmc_host_is_spi(card->host)) {
+               /* host driver already reported errors */
+       } else {
+               if (cmd.resp[0]&  R5_ERROR)
+                       return -EIO;
+               if (cmd.resp[0]&  R5_FUNCTION_NUMBER)
+                       return -EINVAL;
+               if (cmd.resp[0]&  R5_OUT_OF_RANGE)
+                       return -ERANGE;
+       }
+
+       return 0;
+}
+EXPORT_SYMBOL_GPL(mmc_io_rw_extended_sg);
+
  int sdio_reset(struct mmc_host *host)
  {
         int ret;
diff --git a/include/linux/mmc/sdio_func.h b/include/linux/mmc/sdio_func.h
index 50f0bc9..927ea8f 100644
--- a/include/linux/mmc/sdio_func.h
+++ b/include/linux/mmc/sdio_func.h
@@ -14,6 +14,7 @@

  #include<linux/device.h>
  #include<linux/mod_devicetable.h>
+#include<linux/scatterlist.h>

  #include<linux/mmc/pm.h>

@@ -153,6 +154,10 @@ extern int sdio_memcpy_toio(struct sdio_func *func, unsigned int addr,
  extern int sdio_writesb(struct sdio_func *func, unsigned int addr,
         void *src, int count);

+int mmc_io_rw_extended_sg(struct mmc_card *card, int write, unsigned fn,
+                         unsigned addr, int incr_addr,
+                         struct sg_table *sgt, unsigned blksz);
+
  extern unsigned char sdio_f0_readb(struct sdio_func *func,
         unsigned int addr, int *err_ret);
  extern void sdio_f0_writeb(struct sdio_func *func, unsigned char b,
--
1.8.1.4


Kind regards
Uffe
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