Hi Ulf,
Purpose of patch is to offload scatter gather list population to host driver.
Patch provides MMC API using which host driver can directly use to program SG DMA.
Thanks,
Avinash
________________________________________
From: Ulf Hansson [ulf.hansson@xxxxxxxxxx]
Sent: Wednesday, November 26, 2014 7:13 PM
To: Avinash Patil
Cc: linux-mmc; linux-wireless@xxxxxxxxxxxxxxx; Amitkumar Karwar; Cathy Luo; Marc Yang; Xinming Hu; bin9zha0@xxxxxxxxx; Bing Zhao
Subject: Re: [PATCH] mmc: new API for data write using scatter gather DMA
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?
>
> 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
--
To unsubscribe from this list: send the line "unsubscribe linux-mmc" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
