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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 <g.liakhovetski@gmx.de> Acked-by: Samuel Ortiz <sameo@linux.intel.com> Signed-off-by: Chris Ball <cjb@laptop.org>
This commit is contained in:
Guennadi Liakhovetski
Chris Ball
parent
e0bc6ff8b8
commit
93173054f2
@ -111,6 +111,8 @@
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sd_ctrl_write32((host), CTL_STATUS, ~(i)); \
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} while (0)
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/* This is arbitrary, just noone needed any higher alignment yet */
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#define MAX_ALIGN 4
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struct tmio_mmc_host {
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void __iomem *ctl;
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@ -127,6 +129,7 @@ struct tmio_mmc_host {
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/* pio related stuff */
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struct scatterlist *sg_ptr;
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struct scatterlist *sg_orig;
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unsigned int sg_len;
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unsigned int sg_off;
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@ -139,9 +142,13 @@ struct tmio_mmc_host {
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struct tasklet_struct dma_issue;
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#ifdef CONFIG_TMIO_MMC_DMA
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unsigned int dma_sglen;
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u8 bounce_buf[PAGE_CACHE_SIZE] __attribute__((aligned(MAX_ALIGN)));
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struct scatterlist bounce_sg;
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#endif
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};
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static void tmio_check_bounce_buffer(struct tmio_mmc_host *host);
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static u16 sd_ctrl_read16(struct tmio_mmc_host *host, int addr)
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{
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return readw(host->ctl + (addr << host->bus_shift));
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@ -180,6 +187,7 @@ static void tmio_mmc_init_sg(struct tmio_mmc_host *host, struct mmc_data *data)
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{
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host->sg_len = data->sg_len;
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host->sg_ptr = data->sg;
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host->sg_orig = data->sg;
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host->sg_off = 0;
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}
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@ -438,6 +446,8 @@ static void tmio_mmc_do_data_irq(struct tmio_mmc_host *host)
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if (data->flags & MMC_DATA_READ) {
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if (!host->chan_rx)
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disable_mmc_irqs(host, TMIO_MASK_READOP);
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else
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tmio_check_bounce_buffer(host);
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dev_dbg(&host->pdev->dev, "Complete Rx request %p\n",
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host->mrq);
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} else {
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@ -529,8 +539,7 @@ static void tmio_mmc_cmd_irq(struct tmio_mmc_host *host,
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if (!host->chan_rx)
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enable_mmc_irqs(host, TMIO_MASK_READOP);
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} else {
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struct dma_chan *chan = host->chan_tx;
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if (!chan)
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if (!host->chan_tx)
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enable_mmc_irqs(host, TMIO_MASK_WRITEOP);
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else
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tasklet_schedule(&host->dma_issue);
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@ -612,6 +621,16 @@ out:
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}
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#ifdef CONFIG_TMIO_MMC_DMA
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static void tmio_check_bounce_buffer(struct tmio_mmc_host *host)
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{
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if (host->sg_ptr == &host->bounce_sg) {
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unsigned long flags;
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void *sg_vaddr = tmio_mmc_kmap_atomic(host->sg_orig, &flags);
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memcpy(sg_vaddr, host->bounce_buf, host->bounce_sg.length);
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tmio_mmc_kunmap_atomic(sg_vaddr, &flags);
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}
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}
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static void tmio_mmc_enable_dma(struct tmio_mmc_host *host, bool enable)
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{
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#if defined(CONFIG_SUPERH) || defined(CONFIG_ARCH_SHMOBILE)
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@ -634,11 +653,35 @@ static void tmio_dma_complete(void *arg)
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static void tmio_mmc_start_dma_rx(struct tmio_mmc_host *host)
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{
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struct scatterlist *sg = host->sg_ptr;
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struct scatterlist *sg = host->sg_ptr, *sg_tmp;
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struct dma_async_tx_descriptor *desc = NULL;
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struct dma_chan *chan = host->chan_rx;
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struct mfd_cell *cell = host->pdev->dev.platform_data;
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struct tmio_mmc_data *pdata = cell->driver_data;
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dma_cookie_t cookie;
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int ret;
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int ret, i;
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bool aligned = true, multiple = true;
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unsigned int align = (1 << pdata->dma->alignment_shift) - 1;
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for_each_sg(sg, sg_tmp, host->sg_len, i) {
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if (sg_tmp->offset & align)
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aligned = false;
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if (sg_tmp->length & align) {
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multiple = false;
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break;
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}
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}
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if ((!aligned && (host->sg_len > 1 || sg->length > PAGE_CACHE_SIZE ||
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align >= MAX_ALIGN)) || !multiple)
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goto pio;
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/* The only sg element can be unaligned, use our bounce buffer then */
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if (!aligned) {
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sg_init_one(&host->bounce_sg, host->bounce_buf, sg->length);
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host->sg_ptr = &host->bounce_sg;
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sg = host->sg_ptr;
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}
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ret = dma_map_sg(&host->pdev->dev, sg, host->sg_len, DMA_FROM_DEVICE);
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if (ret > 0) {
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@ -661,6 +704,7 @@ static void tmio_mmc_start_dma_rx(struct tmio_mmc_host *host)
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dev_dbg(&host->pdev->dev, "%s(): mapped %d -> %d, cookie %d, rq %p\n",
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__func__, host->sg_len, ret, cookie, host->mrq);
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pio:
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if (!desc) {
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/* DMA failed, fall back to PIO */
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if (ret >= 0)
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@ -684,11 +728,39 @@ static void tmio_mmc_start_dma_rx(struct tmio_mmc_host *host)
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static void tmio_mmc_start_dma_tx(struct tmio_mmc_host *host)
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{
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struct scatterlist *sg = host->sg_ptr;
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struct scatterlist *sg = host->sg_ptr, *sg_tmp;
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struct dma_async_tx_descriptor *desc = NULL;
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struct dma_chan *chan = host->chan_tx;
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struct mfd_cell *cell = host->pdev->dev.platform_data;
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struct tmio_mmc_data *pdata = cell->driver_data;
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dma_cookie_t cookie;
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int ret;
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int ret, i;
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bool aligned = true, multiple = true;
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unsigned int align = (1 << pdata->dma->alignment_shift) - 1;
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for_each_sg(sg, sg_tmp, host->sg_len, i) {
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if (sg_tmp->offset & align)
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aligned = false;
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if (sg_tmp->length & align) {
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multiple = false;
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break;
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}
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}
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if ((!aligned && (host->sg_len > 1 || sg->length > PAGE_CACHE_SIZE ||
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align >= MAX_ALIGN)) || !multiple)
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goto pio;
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/* The only sg element can be unaligned, use our bounce buffer then */
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if (!aligned) {
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unsigned long flags;
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void *sg_vaddr = tmio_mmc_kmap_atomic(sg, &flags);
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sg_init_one(&host->bounce_sg, host->bounce_buf, sg->length);
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memcpy(host->bounce_buf, sg_vaddr, host->bounce_sg.length);
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tmio_mmc_kunmap_atomic(sg_vaddr, &flags);
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host->sg_ptr = &host->bounce_sg;
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sg = host->sg_ptr;
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}
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ret = dma_map_sg(&host->pdev->dev, sg, host->sg_len, DMA_TO_DEVICE);
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if (ret > 0) {
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@ -709,6 +781,7 @@ static void tmio_mmc_start_dma_tx(struct tmio_mmc_host *host)
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dev_dbg(&host->pdev->dev, "%s(): mapped %d -> %d, cookie %d, rq %p\n",
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__func__, host->sg_len, ret, cookie, host->mrq);
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pio:
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if (!desc) {
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/* DMA failed, fall back to PIO */
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if (ret >= 0)
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@ -822,6 +895,10 @@ static void tmio_mmc_release_dma(struct tmio_mmc_host *host)
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}
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}
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#else
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static void tmio_check_bounce_buffer(struct tmio_mmc_host *host)
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{
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}
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static void tmio_mmc_start_dma(struct tmio_mmc_host *host,
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struct mmc_data *data)
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{
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@ -66,6 +66,7 @@ void tmio_core_mmc_clk_div(void __iomem *cnf, int shift, int state);
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struct tmio_mmc_dma {
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void *chan_priv_tx;
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void *chan_priv_rx;
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int alignment_shift;
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};
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/*
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