From: Guennadi Liakhovetski Date: Wed, 22 Dec 2010 11:02:15 +0000 (+0100) Subject: mmc: tmio_mmc: implement a bounce buffer for unaligned DMA X-Git-Tag: firefly_0821_release~7613^2~3064^2~8 X-Git-Url: http://demsky.eecs.uci.edu/git/?a=commitdiff_plain;h=93173054f2979de41b1912b19f0b57edfb35fcdc;p=firefly-linux-kernel-4.4.55.git mmc: tmio_mmc: implement a bounce buffer for unaligned DMA For example, with SDIO WLAN cards, some transfers happen with buffers at odd addresses, whereas the SH-Mobile DMA engine requires even addresses for SDHI. This patch extends the tmio driver with a bounce buffer, that is used for single entry scatter-gather lists both for sending and receiving. If we ever encounter unaligned transfers with multi-element sg lists, this patch will have to be extended. For now it just falls back to PIO in this and other unsupported cases. Signed-off-by: Guennadi Liakhovetski Acked-by: Samuel Ortiz Signed-off-by: Chris Ball --- diff --git a/drivers/mmc/host/tmio_mmc.c b/drivers/mmc/host/tmio_mmc.c index e04c032abb1c..595b7b3f160d 100644 --- a/drivers/mmc/host/tmio_mmc.c +++ b/drivers/mmc/host/tmio_mmc.c @@ -111,6 +111,8 @@ sd_ctrl_write32((host), CTL_STATUS, ~(i)); \ } while (0) +/* This is arbitrary, just noone needed any higher alignment yet */ +#define MAX_ALIGN 4 struct tmio_mmc_host { void __iomem *ctl; @@ -127,6 +129,7 @@ struct tmio_mmc_host { /* pio related stuff */ struct scatterlist *sg_ptr; + struct scatterlist *sg_orig; unsigned int sg_len; unsigned int sg_off; @@ -139,9 +142,13 @@ struct tmio_mmc_host { struct tasklet_struct dma_issue; #ifdef CONFIG_TMIO_MMC_DMA unsigned int dma_sglen; + u8 bounce_buf[PAGE_CACHE_SIZE] __attribute__((aligned(MAX_ALIGN))); + struct scatterlist bounce_sg; #endif }; +static void tmio_check_bounce_buffer(struct tmio_mmc_host *host); + static u16 sd_ctrl_read16(struct tmio_mmc_host *host, int addr) { return readw(host->ctl + (addr << host->bus_shift)); @@ -180,6 +187,7 @@ static void tmio_mmc_init_sg(struct tmio_mmc_host *host, struct mmc_data *data) { host->sg_len = data->sg_len; host->sg_ptr = data->sg; + host->sg_orig = data->sg; host->sg_off = 0; } @@ -438,6 +446,8 @@ static void tmio_mmc_do_data_irq(struct tmio_mmc_host *host) if (data->flags & MMC_DATA_READ) { if (!host->chan_rx) disable_mmc_irqs(host, TMIO_MASK_READOP); + else + tmio_check_bounce_buffer(host); dev_dbg(&host->pdev->dev, "Complete Rx request %p\n", host->mrq); } else { @@ -529,8 +539,7 @@ static void tmio_mmc_cmd_irq(struct tmio_mmc_host *host, if (!host->chan_rx) enable_mmc_irqs(host, TMIO_MASK_READOP); } else { - struct dma_chan *chan = host->chan_tx; - if (!chan) + if (!host->chan_tx) enable_mmc_irqs(host, TMIO_MASK_WRITEOP); else tasklet_schedule(&host->dma_issue); @@ -612,6 +621,16 @@ out: } #ifdef CONFIG_TMIO_MMC_DMA +static void tmio_check_bounce_buffer(struct tmio_mmc_host *host) +{ + if (host->sg_ptr == &host->bounce_sg) { + unsigned long flags; + void *sg_vaddr = tmio_mmc_kmap_atomic(host->sg_orig, &flags); + memcpy(sg_vaddr, host->bounce_buf, host->bounce_sg.length); + tmio_mmc_kunmap_atomic(sg_vaddr, &flags); + } +} + static void tmio_mmc_enable_dma(struct tmio_mmc_host *host, bool enable) { #if defined(CONFIG_SUPERH) || defined(CONFIG_ARCH_SHMOBILE) @@ -634,11 +653,35 @@ static void tmio_dma_complete(void *arg) static void tmio_mmc_start_dma_rx(struct tmio_mmc_host *host) { - struct scatterlist *sg = host->sg_ptr; + struct scatterlist *sg = host->sg_ptr, *sg_tmp; struct dma_async_tx_descriptor *desc = NULL; struct dma_chan *chan = host->chan_rx; + struct mfd_cell *cell = host->pdev->dev.platform_data; + struct tmio_mmc_data *pdata = cell->driver_data; dma_cookie_t cookie; - int ret; + int ret, i; + bool aligned = true, multiple = true; + unsigned int align = (1 << pdata->dma->alignment_shift) - 1; + + for_each_sg(sg, sg_tmp, host->sg_len, i) { + if (sg_tmp->offset & align) + aligned = false; + if (sg_tmp->length & align) { + multiple = false; + break; + } + } + + if ((!aligned && (host->sg_len > 1 || sg->length > PAGE_CACHE_SIZE || + align >= MAX_ALIGN)) || !multiple) + goto pio; + + /* The only sg element can be unaligned, use our bounce buffer then */ + if (!aligned) { + sg_init_one(&host->bounce_sg, host->bounce_buf, sg->length); + host->sg_ptr = &host->bounce_sg; + sg = host->sg_ptr; + } ret = dma_map_sg(&host->pdev->dev, sg, host->sg_len, DMA_FROM_DEVICE); if (ret > 0) { @@ -661,6 +704,7 @@ static void tmio_mmc_start_dma_rx(struct tmio_mmc_host *host) dev_dbg(&host->pdev->dev, "%s(): mapped %d -> %d, cookie %d, rq %p\n", __func__, host->sg_len, ret, cookie, host->mrq); +pio: if (!desc) { /* DMA failed, fall back to PIO */ if (ret >= 0) @@ -684,11 +728,39 @@ static void tmio_mmc_start_dma_rx(struct tmio_mmc_host *host) static void tmio_mmc_start_dma_tx(struct tmio_mmc_host *host) { - struct scatterlist *sg = host->sg_ptr; + struct scatterlist *sg = host->sg_ptr, *sg_tmp; struct dma_async_tx_descriptor *desc = NULL; struct dma_chan *chan = host->chan_tx; + struct mfd_cell *cell = host->pdev->dev.platform_data; + struct tmio_mmc_data *pdata = cell->driver_data; dma_cookie_t cookie; - int ret; + int ret, i; + bool aligned = true, multiple = true; + unsigned int align = (1 << pdata->dma->alignment_shift) - 1; + + for_each_sg(sg, sg_tmp, host->sg_len, i) { + if (sg_tmp->offset & align) + aligned = false; + if (sg_tmp->length & align) { + multiple = false; + break; + } + } + + if ((!aligned && (host->sg_len > 1 || sg->length > PAGE_CACHE_SIZE || + align >= MAX_ALIGN)) || !multiple) + goto pio; + + /* The only sg element can be unaligned, use our bounce buffer then */ + if (!aligned) { + unsigned long flags; + void *sg_vaddr = tmio_mmc_kmap_atomic(sg, &flags); + sg_init_one(&host->bounce_sg, host->bounce_buf, sg->length); + memcpy(host->bounce_buf, sg_vaddr, host->bounce_sg.length); + tmio_mmc_kunmap_atomic(sg_vaddr, &flags); + host->sg_ptr = &host->bounce_sg; + sg = host->sg_ptr; + } ret = dma_map_sg(&host->pdev->dev, sg, host->sg_len, DMA_TO_DEVICE); if (ret > 0) { @@ -709,6 +781,7 @@ static void tmio_mmc_start_dma_tx(struct tmio_mmc_host *host) dev_dbg(&host->pdev->dev, "%s(): mapped %d -> %d, cookie %d, rq %p\n", __func__, host->sg_len, ret, cookie, host->mrq); +pio: if (!desc) { /* DMA failed, fall back to PIO */ if (ret >= 0) @@ -822,6 +895,10 @@ static void tmio_mmc_release_dma(struct tmio_mmc_host *host) } } #else +static void tmio_check_bounce_buffer(struct tmio_mmc_host *host) +{ +} + static void tmio_mmc_start_dma(struct tmio_mmc_host *host, struct mmc_data *data) { diff --git a/include/linux/mfd/tmio.h b/include/linux/mfd/tmio.h index 085f041197dc..dbfc053b1f95 100644 --- a/include/linux/mfd/tmio.h +++ b/include/linux/mfd/tmio.h @@ -66,6 +66,7 @@ void tmio_core_mmc_clk_div(void __iomem *cnf, int shift, int state); struct tmio_mmc_dma { void *chan_priv_tx; void *chan_priv_rx; + int alignment_shift; }; /*