Hi,
On 29/11/18 11:37 AM, Chunyan Zhang wrote:
> Some standard SD host controllers can support both external dma
> controllers as well as ADMA/SDMA in which the SD host controller
> acts as DMA master. TI's omap controller is the case as an example.
>
> Currently the generic SDHCI code supports ADMA/SDMA integrated in
> the host controller but does not have any support for external DMA
> controllers implemented using dmaengine, meaning that custom code is
> needed for any systems that use an external DMA controller with SDHCI.
>
> Signed-off-by: Chunyan Zhang <zhang.chun...@linaro.org>
> ---
> drivers/mmc/host/Kconfig | 14 ++++
> drivers/mmc/host/sdhci.c | 185
> ++++++++++++++++++++++++++++++++++++++++++++++-
> drivers/mmc/host/sdhci.h | 8 ++
> 3 files changed, 206 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/mmc/host/Kconfig b/drivers/mmc/host/Kconfig
> index 1b58739..4183f43 100644
> --- a/drivers/mmc/host/Kconfig
> +++ b/drivers/mmc/host/Kconfig
> @@ -969,6 +969,7 @@ config MMC_SDHCI_XENON
> config MMC_SDHCI_OMAP
> tristate "TI SDHCI Controller Support"
> depends on MMC_SDHCI_PLTFM && OF
> + select MMC_SDHCI_EXTERNAL_DMA if DMA_ENGINE
> help
> This selects the Secure Digital Host Controller Interface (SDHCI)
> support present in TI's DRA7 SOCs. The controller supports
> @@ -977,3 +978,16 @@ config MMC_SDHCI_OMAP
> If you have a controller with this interface, say Y or M here.
>
> If unsure, say N.
> +
> +config MMC_SDHCI_EXTERNAL_DMA
> + bool "Support external DMA in standard SD host controller"
> + depends on MMC_SDHCI
> + depends on DMA_ENGINE
> + help
> + This is an option for using external DMA device via dmaengine
> + framework.
> +
> + If you have a controller which support using external DMA device
> + for data transfer, can say Y.
> +
> + If unsure, say N.
> diff --git a/drivers/mmc/host/sdhci.c b/drivers/mmc/host/sdhci.c
> index 99bdae5..ad7cc80 100644
> --- a/drivers/mmc/host/sdhci.c
> +++ b/drivers/mmc/host/sdhci.c
> @@ -14,6 +14,7 @@
> */
>
> #include <linux/delay.h>
> +#include <linux/dmaengine.h>
> #include <linux/ktime.h>
> #include <linux/highmem.h>
> #include <linux/io.h>
> @@ -1309,6 +1310,162 @@ static void sdhci_del_timer(struct sdhci_host *host,
> struct mmc_request *mrq)
> del_timer(&host->timer);
> }
>
> +#if IS_ENABLED(CONFIG_MMC_SDHCI_EXTERNAL_DMA)
> +static int sdhci_external_dma_init(struct sdhci_host *host)
> +{
> + int ret = 0;
> + struct mmc_host *mmc = host->mmc;
> +
> + host->tx_chan = dma_request_chan(mmc->parent, "tx");
> + if (IS_ERR(host->tx_chan)) {
> + ret = PTR_ERR(host->tx_chan);
> + if (ret != -EPROBE_DEFER)
> + pr_warn("Failed to request TX DMA channel.\n");
> + host->tx_chan = NULL;
> + return ret;
> + }
> +
> + host->rx_chan = dma_request_chan(mmc->parent, "rx");
> + if (IS_ERR(host->rx_chan)) {
> + if (host->tx_chan) {
> + dma_release_channel(host->tx_chan);
> + host->tx_chan = NULL;
> + }
> +
> + ret = PTR_ERR(host->rx_chan);
> + if (ret != -EPROBE_DEFER)
> + pr_warn("Failed to request RX DMA channel.\n");
> + host->rx_chan = NULL;
> + }
> +
> + return ret;
> +}
> +
> +static inline struct dma_chan *
> +sdhci_external_dma_channel(struct sdhci_host *host, struct mmc_data *data)
> +{
> + return data->flags & MMC_DATA_WRITE ? host->tx_chan : host->rx_chan;
> +}
> +
> +static int sdhci_external_dma_setup(struct sdhci_host *host,
> + struct mmc_command *cmd)
> +{
> + int ret, i;
> + struct dma_async_tx_descriptor *desc;
> + struct mmc_data *data = cmd->data;
> + struct dma_chan *chan;
> + struct dma_slave_config cfg;
> + dma_cookie_t cookie;
> +
> + if (!host->mapbase)
> + return -EINVAL;
> +
> + if (!data)
> + return 0;
> +
> + cfg.src_addr = host->mapbase + SDHCI_BUFFER;
> + cfg.dst_addr = host->mapbase + SDHCI_BUFFER;
> + cfg.src_addr_width = DMA_SLAVE_BUSWIDTH_4_BYTES;
> + cfg.dst_addr_width = DMA_SLAVE_BUSWIDTH_4_BYTES;
> + cfg.src_maxburst = data->blksz / 4;
> + cfg.dst_maxburst = data->blksz / 4;
> +
> + /* Sanity check: all the SG entries must be aligned by block size. */
> + for (i = 0; i < data->sg_len; i++) {
> + if ((data->sg + i)->length % data->blksz)
> + return -EINVAL;
> + }
> +
> + chan = sdhci_external_dma_channel(host, data);
> +
> + ret = dmaengine_slave_config(chan, &cfg);
> + if (ret)
> + return ret;
> +
> + desc = dmaengine_prep_slave_sg(chan, data->sg, data->sg_len,
> + mmc_get_dma_dir(data),
> + DMA_PREP_INTERRUPT | DMA_CTRL_ACK);
> + if (!desc)
> + return -EINVAL;
> +
> + desc->callback = NULL;
> + desc->callback_param = NULL;
> +
> + cookie = dmaengine_submit(desc);
> + if (cookie < 0)
> + ret = cookie;
> +
> + return ret;
> +}
> +
> +static void sdhci_external_dma_release(struct sdhci_host *host)
> +{
> + if (host->tx_chan) {
> + dma_release_channel(host->tx_chan);
> + host->tx_chan = NULL;
> + }
> +
> + if (host->rx_chan) {
> + dma_release_channel(host->rx_chan);
> + host->rx_chan = NULL;
> + }
> +
> + sdhci_switch_external_dma(host, false);
> +}
> +
> +static void sdhci_external_dma_prepare_data(struct sdhci_host *host,
> + struct mmc_command *cmd)
> +{
Please add a condition for data == NULL here. This was already pointed
out by Adrian in v2.
My test with an am335x-evm failed with these patches. Looks like the
very first SDIO commands failing.
https://pastebin.ubuntu.com/p/Y2RDjSKpgd/
Currently am335x-evm is using omap_hsmmc driver. I added the following
patch to make it work with sdhci_omap.
https://pastebin.ubuntu.com/p/VTGrCbJxY3/
Will look deeper into this. Please ping if you need any more information.
Thanks,
Faiz
