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SubjectRe: [PATCH v4 03/11] mmc: sdhci: add support for using external DMA devices
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Date
On 6/01/20 1:01 pm, Faiz Abbas wrote:
> From: Chunyan Zhang <zhang.chunyan@linaro.org>
>
> 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.
>
> Fixes by Faiz Abbas <faiz_abbas@ti.com>:
> 1. Map scatterlists before dmaengine_prep_slave_sg()
> 2. Use dma_async() functions inside of the send_command() path and call
> terminate_sync() in non-atomic context in case of an error.
>
> Signed-off-by: Chunyan Zhang <zhang.chunyan@linaro.org>
> Signed-off-by: Faiz Abbas <faiz_abbas@ti.com>

Notwithstanding comments from other people:

Acked-by: Adrian Hunter <adrian.hunter@intel.com>

> ---
> drivers/mmc/host/Kconfig | 3 +
> drivers/mmc/host/sdhci.c | 228 ++++++++++++++++++++++++++++++++++++++-
> drivers/mmc/host/sdhci.h | 8 ++
> 3 files changed, 237 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/mmc/host/Kconfig b/drivers/mmc/host/Kconfig
> index d06b2dfe3c95..adef971582a1 100644
> --- a/drivers/mmc/host/Kconfig
> +++ b/drivers/mmc/host/Kconfig
> @@ -1040,3 +1040,6 @@ config MMC_OWL
> help
> This selects support for the SD/MMC Host Controller on
> Actions Semi Owl SoCs.
> +
> +config MMC_SDHCI_EXTERNAL_DMA
> + bool
> diff --git a/drivers/mmc/host/sdhci.c b/drivers/mmc/host/sdhci.c
> index f6999054abcf..8cc78c76bc3d 100644
> --- a/drivers/mmc/host/sdhci.c
> +++ b/drivers/mmc/host/sdhci.c
> @@ -10,6 +10,7 @@
> */
>
> #include <linux/delay.h>
> +#include <linux/dmaengine.h>
> #include <linux/ktime.h>
> #include <linux/highmem.h>
> #include <linux/io.h>
> @@ -1157,6 +1158,188 @@ static void sdhci_prepare_data(struct sdhci_host *host, struct mmc_command *cmd)
> sdhci_set_block_info(host, data);
> }
>
> +#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 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;
> + int sg_cnt;
> +
> + if (!host->mapbase)
> + return -EINVAL;
> +
> + 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;
> +
> + sg_cnt = sdhci_pre_dma_transfer(host, data, COOKIE_MAPPED);
> + if (sg_cnt <= 0)
> + return -EINVAL;
> +
> + 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)
> +{
> + struct mmc_data *data = cmd->data;
> +
> + sdhci_initialize_data(host, data);
> +
> + host->flags |= SDHCI_REQ_USE_DMA;
> + sdhci_set_transfer_irqs(host);
> +
> + sdhci_set_block_info(host, data);
> +}
> +
> +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_prepare_data(host, cmd);
> + } else {
> + sdhci_external_dma_release(host);
> + pr_err("%s: Cannot use external DMA, switch to the DMA/PIO which standard SDHCI provides.\n",
> + mmc_hostname(host->mmc));
> + 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->data)
> + return;
> +
> + chan = sdhci_external_dma_channel(host, cmd->data);
> + if (chan)
> + dma_async_issue_pending(chan);
> +}
> +
> +#else
> +
> +static inline int sdhci_external_dma_init(struct sdhci_host *host)
> +{
> + return -EOPNOTSUPP;
> +}
> +
> +static inline void sdhci_external_dma_release(struct sdhci_host *host)
> +{
> +}
> +
> +static inline void sdhci_external_dma_prepare_data(struct sdhci_host *host,
> + struct mmc_command *cmd)
> +{
> + /* This should never happen */
> + WARN_ON_ONCE(1);
> +}
> +
> +static inline void sdhci_external_dma_pre_transfer(struct sdhci_host *host,
> + struct mmc_command *cmd)
> +{
> +}
> +
> +static inline struct dma_chan *sdhci_external_dma_channel(struct sdhci_host *host,
> + struct mmc_data *data)
> +{
> + return NULL;
> +}
> +
> +#endif
> +
> +void sdhci_switch_external_dma(struct sdhci_host *host, bool en)
> +{
> + host->use_external_dma = en;
> +}
> +EXPORT_SYMBOL_GPL(sdhci_switch_external_dma);
> +
> static inline bool sdhci_auto_cmd12(struct sdhci_host *host,
> struct mmc_request *mrq)
> {
> @@ -1408,8 +1591,12 @@ void sdhci_send_command(struct sdhci_host *host, struct mmc_command *cmd)
> sdhci_set_timeout(host, cmd);
> }
>
> - if (cmd->data)
> - sdhci_prepare_data(host, cmd);
> + if (cmd->data) {
> + 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);
>
> @@ -1451,6 +1638,9 @@ 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);
> @@ -2675,6 +2865,17 @@ static bool sdhci_request_done(struct sdhci_host *host)
> if (host->flags & SDHCI_REQ_USE_DMA) {
> struct mmc_data *data = mrq->data;
>
> + if (host->use_external_dma && data &&
> + (mrq->cmd->error || data->error)) {
> + struct dma_chan *chan = sdhci_external_dma_channel(host, data);
> +
> + host->mrqs_done[i] = NULL;
> + spin_unlock_irqrestore(&host->lock, flags);
> + dmaengine_terminate_sync(chan);
> + spin_lock_irqsave(&host->lock, flags);
> + sdhci_set_mrq_done(host, mrq);
> + }
> +
> if (data && data->host_cookie == COOKIE_MAPPED) {
> if (host->bounce_buffer) {
> /*
> @@ -3810,6 +4011,21 @@ int sdhci_setup_host(struct sdhci_host *host)
> if (sdhci_can_64bit_dma(host))
> host->flags |= SDHCI_USE_64_BIT_DMA;
>
> + 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.
> + */
> + else if (ret)
> + sdhci_switch_external_dma(host, false);
> + /* Disable internal DMA sources */
> + else
> + host->flags &= ~(SDHCI_USE_SDMA | SDHCI_USE_ADMA);
> + }
> +
> if (host->flags & (SDHCI_USE_SDMA | SDHCI_USE_ADMA)) {
> if (host->ops->set_dma_mask)
> ret = host->ops->set_dma_mask(host);
> @@ -4290,6 +4506,10 @@ 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;
> }
> @@ -4335,6 +4555,7 @@ int __sdhci_add_host(struct sdhci_host *host)
>
> pr_info("%s: SDHCI controller on %s [%s] using %s\n",
> mmc_hostname(mmc), host->hw_name, dev_name(mmc_dev(mmc)),
> + host->use_external_dma ? "External DMA" :
> (host->flags & SDHCI_USE_ADMA) ?
> (host->flags & SDHCI_USE_64_BIT_DMA) ? "ADMA 64-bit" : "ADMA" :
> (host->flags & SDHCI_USE_SDMA) ? "DMA" : "PIO");
> @@ -4423,6 +4644,9 @@ 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 fe83ece6965b..3166b3ecef89 100644
> --- a/drivers/mmc/host/sdhci.h
> +++ b/drivers/mmc/host/sdhci.h
> @@ -487,6 +487,7 @@ 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;
> @@ -535,6 +536,7 @@ 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; /* Host selects to use external DMA */
>
> struct mmc_request *mrqs_done[SDHCI_MAX_MRQS]; /* Requests done */
> struct mmc_command *cmd; /* Current command */
> @@ -564,6 +566,11 @@ 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 */
> @@ -795,5 +802,6 @@ 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_abort_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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