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Date: Thu, 29 Nov 2018 17:44:52 +0800
From: Chunyan Zhang <zhang.lyra@...il.com>
To: Adrian Hunter <adrian.hunter@...el.com>
Cc: Chunyan Zhang <zhang.chunyan@...aro.org>,
Ulf Hansson <ulf.hansson@...aro.org>, faiz_abbas@...com,
linux-mmc@...r.kernel.org,
Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
Arnd Bergmann <arnd@...db.de>, Mark Brown <broonie@...nel.org>,
kishon@...com, nsekhar@...com
Subject: Re: [PATCH V3 1/3] mmc: sdhci: add support for using external DMA devices
On Thu, 29 Nov 2018 at 17:25, Adrian Hunter <adrian.hunter@...el.com> wrote:
>
> On 29/11/18 8:07 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.chunyan@...aro.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.
>
> So if you are going to select this, then you don't need the prompt or help
> anymore i.e.
>
> config MMC_SDHCI_EXTERNAL_DMA
> bool
>
>
> > 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;
>
> It would read better if the above 2 if-statements were the other way around i.e.
>
> if (!data)
> return 0;
>
> if (!host->mapbase)
> return -EINVAL;
>
Ok.
> > +
> > + 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)
> > +{
> > + if (sdhci_external_dma_setup(host, cmd)) {
> > + sdhci_external_dma_release(host);
> > + pr_err("%s: Failed to setup external DMA, switch to the DMA/PIO which standard SDHCI provides.\n",
> > + mmc_hostname(host->mmc));
> > + } else {
> > + /* Prepare for using external dma */
> > + host->flags |= SDHCI_REQ_USE_DMA;
> > + }
> > +
> > + sdhci_prepare_data(host, cmd);
> > +}
> > +
> > +static void sdhci_external_dma_pre_transfer(struct sdhci_host *host,
> > + struct mmc_command *cmd)
> > +{
> > + struct dma_chan *chan;
> > +
> > + if (cmd->opcode != MMC_SET_BLOCK_COUNT && cmd->data) {
>
> MMC_SET_BLOCK_COUNT doesn't have data so that part is not needed
Didn't get you here.
This is for other packets except MMC_SET_BLOCK_COUNT.
>
> > + sdhci_set_timeout(host, cmd);
> > + chan = sdhci_external_dma_channel(host, cmd->data);
> > + dma_async_issue_pending(chan);
> > + }
> > +}
> > +#else
> > +static int sdhci_external_dma_init(struct sdhci_host *host)
> > +{
> > + return -EOPNOTSUPP;
> > +}
> > +
> > +static void sdhci_external_dma_release(struct sdhci_host *host)
> > +{}
> > +
> > +static void sdhci_external_dma_prepare_data(struct sdhci_host *host,
> > + struct mmc_command *cmd)
> > +{
> > + /* If MMC_SDHCI_EXTERNAL_DMA not supported, PIO will be used */
> > + sdhci_prepare_data(host, cmd);
> > +}
> > +
> > +static void sdhci_external_dma_pre_transfer(struct sdhci_host *host,
> > + struct mmc_command *cmd)
> > +{}
> > +#endif
> > +
> > +void sdhci_switch_external_dma(struct sdhci_host *host, bool en)
> > +{
> > + host->use_external_dma = en;
> > +}
> > +EXPORT_SYMBOL_GPL(sdhci_switch_external_dma);
> > +
> > void sdhci_send_command(struct sdhci_host *host, struct mmc_command *cmd)
> > {
> > int flags;
> > @@ -1355,7 +1512,10 @@ void sdhci_send_command(struct sdhci_host *host, struct mmc_command *cmd)
> > host->data_cmd = cmd;
> > }
> >
> > - sdhci_prepare_data(host, cmd);
> > + if (host->use_external_dma)
> > + sdhci_external_dma_prepare_data(host, cmd);
> > + else
> > + sdhci_prepare_data(host, cmd);
> >
> > sdhci_writel(host, cmd->arg, SDHCI_ARGUMENT);
> >
> > @@ -1397,6 +1557,9 @@ void sdhci_send_command(struct sdhci_host *host, struct mmc_command *cmd)
> > timeout += 10 * HZ;
> > sdhci_mod_timer(host, cmd->mrq, timeout);
> >
> > + if (host->use_external_dma)
> > + sdhci_external_dma_pre_transfer(host, cmd);
> > +
> > sdhci_writew(host, SDHCI_MAKE_CMD(cmd->opcode, flags), SDHCI_COMMAND);
> > }
> > EXPORT_SYMBOL_GPL(sdhci_send_command);
> > @@ -4133,6 +4296,19 @@ int sdhci_setup_host(struct sdhci_host *host)
> > return ret;
> > }
> >
> > + if (host->use_external_dma) {
> > + ret = sdhci_external_dma_init(host);
> > + if (ret == -EPROBE_DEFER)
> > + goto unreg;
> > +
> > + /*
> > + * Fall back to use the DMA/PIO integrated in standard SDHCI
> > + * instead of external DMA devices.
> > + */
> > + if (ret)
> > + sdhci_switch_external_dma(host, false);
> > + }
> > +
> > return 0;
> >
> > unreg:
> > @@ -4161,6 +4337,10 @@ void sdhci_cleanup_host(struct sdhci_host *host)
> > dma_free_coherent(mmc_dev(mmc), host->align_buffer_sz +
> > host->adma_table_sz, host->align_buffer,
> > host->align_addr);
> > +
> > + if (host->use_external_dma)
> > + sdhci_external_dma_release(host);
> > +
> > host->adma_table = NULL;
> > host->align_buffer = NULL;
> > }
> > @@ -4295,6 +4475,9 @@ void sdhci_remove_host(struct sdhci_host *host, int dead)
> > host->adma_table_sz, host->align_buffer,
> > host->align_addr);
> >
> > + if (host->use_external_dma)
> > + sdhci_external_dma_release(host);
> > +
> > host->adma_table = NULL;
> > host->align_buffer = NULL;
> > }
> > diff --git a/drivers/mmc/host/sdhci.h b/drivers/mmc/host/sdhci.h
> > index b001cf4..8e50a97 100644
> > --- a/drivers/mmc/host/sdhci.h
> > +++ b/drivers/mmc/host/sdhci.h
> > @@ -475,6 +475,7 @@ struct sdhci_host {
> >
> > int irq; /* Device IRQ */
> > void __iomem *ioaddr; /* Mapped address */
> > + phys_addr_t mapbase; /* physical address base */
> > char *bounce_buffer; /* For packing SDMA reads/writes */
> > dma_addr_t bounce_addr;
> > unsigned int bounce_buffer_size;
> > @@ -524,6 +525,7 @@ struct sdhci_host {
> > bool pending_reset; /* Cmd/data reset is pending */
> > bool irq_wake_enabled; /* IRQ wakeup is enabled */
> > bool v4_mode; /* Host Version 4 Enable */
> > + bool use_external_dma;
> >
> > struct mmc_request *mrqs_done[SDHCI_MAX_MRQS]; /* Requests done */
> > struct mmc_command *cmd; /* Current command */
> > @@ -552,6 +554,11 @@ struct sdhci_host {
> > struct timer_list timer; /* Timer for timeouts */
> > struct timer_list data_timer; /* Timer for data timeouts */
> >
> > +#if IS_ENABLED(CONFIG_MMC_SDHCI_EXTERNAL_DMA)
> > + struct dma_chan *rx_chan;
> > + struct dma_chan *tx_chan;
> > +#endif
> > +
> > u32 caps; /* CAPABILITY_0 */
> > u32 caps1; /* CAPABILITY_1 */
> > bool read_caps; /* Capability flags have been read */
> > @@ -785,5 +792,6 @@ void sdhci_start_tuning(struct sdhci_host *host);
> > void sdhci_end_tuning(struct sdhci_host *host);
> > void sdhci_reset_tuning(struct sdhci_host *host);
> > void sdhci_send_tuning(struct sdhci_host *host, u32 opcode);
> > +void sdhci_switch_external_dma(struct sdhci_host *host, bool en);
> >
> > #endif /* __SDHCI_HW_H */
> >
>
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