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Message-ID: <1d3484c6-6f9e-847c-3e22-9b1726700a37@ti.com>
Date: Tue, 7 Jun 2016 12:17:13 +0300
From: Peter Ujfalusi <peter.ujfalusi@...com>
To: Vignesh R <vigneshr@...com>, Mark Brown <broonie@...nel.org>
CC: <linux-spi@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
<linux-omap@...r.kernel.org>
Subject: Re: [PATCH v3 2/2] spi: spi-ti-qspi: Add DMA support for QSPI mmap
read
On 06/07/16 11:18, Vignesh R wrote:
> Use mem-to-mem DMA to read from flash when reading in mmap mode. This
> gives improved read performance and reduces CPU load.
>
> With this patch the raw-read throughput is ~16MB/s on DRA74 EVM. And CPU
> load is <20%. UBIFS read ~13 MB/s.
>
> Signed-off-by: Vignesh R <vigneshr@...com>
> ---
>
> v3: Cleanup code based on review comments for v2.
> v2: Handle kmap'd buffers of JFFS2 FS.
>
> drivers/spi/spi-ti-qspi.c | 189 ++++++++++++++++++++++++++++++++++++++++++----
> 1 file changed, 176 insertions(+), 13 deletions(-)
>
> diff --git a/drivers/spi/spi-ti-qspi.c b/drivers/spi/spi-ti-qspi.c
> index 29ea8d2f9824..1f6c59c29157 100644
> --- a/drivers/spi/spi-ti-qspi.c
> +++ b/drivers/spi/spi-ti-qspi.c
> @@ -33,6 +33,7 @@
> #include <linux/pinctrl/consumer.h>
> #include <linux/mfd/syscon.h>
> #include <linux/regmap.h>
> +#include <linux/highmem.h>
>
> #include <linux/spi/spi.h>
>
> @@ -41,6 +42,8 @@ struct ti_qspi_regs {
> };
>
> struct ti_qspi {
> + struct completion transfer_complete;
> +
> /* list synchronization */
> struct mutex list_lock;
>
> @@ -54,6 +57,9 @@ struct ti_qspi {
>
> struct ti_qspi_regs ctx_reg;
>
> + dma_addr_t mmap_phys_base;
> + struct dma_chan *rx_chan;
> +
> u32 spi_max_frequency;
> u32 cmd;
> u32 dc;
> @@ -379,6 +385,72 @@ static int qspi_transfer_msg(struct ti_qspi *qspi, struct spi_transfer *t,
> return 0;
> }
>
> +static void ti_qspi_dma_callback(void *param)
> +{
> + struct ti_qspi *qspi = param;
> +
> + complete(&qspi->transfer_complete);
> +}
> +
> +static int ti_qspi_dma_xfer(struct ti_qspi *qspi, dma_addr_t dma_dst,
> + dma_addr_t dma_src, size_t len)
> +{
> + struct dma_chan *chan = qspi->rx_chan;
> + struct dma_device *dma_dev = chan->device;
> + dma_cookie_t cookie;
> + enum dma_ctrl_flags flags = DMA_CTRL_ACK | DMA_PREP_INTERRUPT;
> + struct dma_async_tx_descriptor *tx;
> + int ret;
> +
> + tx = dma_dev->device_prep_dma_memcpy(chan, dma_dst, dma_src,
> + len, flags);
> + if (!tx) {
> + dev_err(qspi->dev, "device_prep_dma_memcpy error\n");
> + return -EIO;
> + }
> +
> + tx->callback = ti_qspi_dma_callback;
> + tx->callback_param = qspi;
> + cookie = tx->tx_submit(tx);
> +
> + ret = dma_submit_error(cookie);
> + if (ret) {
> + dev_err(qspi->dev, "dma_submit_error %d\n", cookie);
> + return -EIO;
> + }
> +
> + dma_async_issue_pending(chan);
> + ret = wait_for_completion_timeout(&qspi->transfer_complete,
> + msecs_to_jiffies(len));
> + if (ret <= 0) {
> + dmaengine_terminate_sync(chan);
> + dev_err(qspi->dev, "DMA wait_for_completion_timeout\n");
> + return -ETIMEDOUT;
> + }
> +
> + return 0;
> +}
> +
> +static int ti_qspi_dma_xfer_sg(struct ti_qspi *qspi, struct sg_table rx_sg,
> + loff_t from)
> +{
> + struct scatterlist *sg;
> + dma_addr_t dma_src = qspi->mmap_phys_base + from;
> + dma_addr_t dma_dst;
> + int i, len, ret;
> +
> + for_each_sg(rx_sg.sgl, sg, rx_sg.nents, i) {
> + dma_dst = sg_dma_address(sg);
> + len = sg_dma_len(sg);
> + ret = ti_qspi_dma_xfer(qspi, dma_dst, dma_src, len);
> + if (ret)
> + return ret;
> + dma_src += len;
> + }
> +
> + return 0;
> +}
> +
> static void ti_qspi_enable_memory_map(struct spi_device *spi)
> {
> struct ti_qspi *qspi = spi_master_get_devdata(spi->master);
> @@ -426,7 +498,40 @@ static void ti_qspi_setup_mmap_read(struct spi_device *spi,
> QSPI_SPI_SETUP_REG(spi->chip_select));
> }
>
> -static int ti_qspi_spi_flash_read(struct spi_device *spi,
> +#ifdef CONFIG_HIGHMEM
> +static int ti_qspi_map_buf(struct ti_qspi *qspi, void *buf,
> + unsigned int len, struct sg_table *sgt)
> +{
> + unsigned int max_seg_size =
> + dma_get_max_seg_size(qspi->rx_chan->device->dev);
> + unsigned int desc_len = min_t(int, max_seg_size, PAGE_SIZE);
> + int sgs = DIV_ROUND_UP(len + offset_in_page(buf), desc_len);
> + struct page *vm_page;
> + size_t min;
> + int i, ret;
> +
> + ret = sg_alloc_table(sgt, sgs, GFP_KERNEL);
> + if (ret)
> + return ret;
> +
> + for (i = 0; i < sgs; i++) {
> + min = min_t(size_t, len, desc_len -
> + offset_in_page(buf));
> + vm_page = kmap_to_page(buf);
> + if (!vm_page) {
> + sg_free_table(sgt);
> + return -ENOMEM;
> + }
> + sg_set_page(&sgt->sgl[i], vm_page, min,
> + offset_in_page(buf));
> + buf += min;
> + len -= min;
> + }
> + return 0;
> +}
> +#endif
> +
> +static int ti_qspi_spi_flash_read(struct spi_device *spi,
> struct spi_flash_read_message *msg)
> {
> struct ti_qspi *qspi = spi_master_get_devdata(spi->master);
> @@ -437,9 +542,46 @@ static int ti_qspi_spi_flash_read(struct spi_device *spi,
> if (!qspi->mmap_enabled)
> ti_qspi_enable_memory_map(spi);
> ti_qspi_setup_mmap_read(spi, msg);
> - memcpy_fromio(msg->buf, qspi->mmap_base + msg->from, msg->len);
> +
> + if (qspi->rx_chan) {
> + struct device *dev = qspi->rx_chan->device->dev;
> + void *buf = msg->buf;
> + struct sg_table sgt;
> +
> + if (msg->cur_msg_mapped) {
> + ret = ti_qspi_dma_xfer_sg(qspi, msg->rx_sg, msg->from);
> + if (ret)
> + goto err_unlock;
> +#ifdef CONFIG_HIGHMEM
> + } else if ((unsigned long)buf >= PKMAP_BASE &&
> + (unsigned long)buf < (PKMAP_BASE +
> + (LAST_PKMAP * PAGE_SIZE))) {
> + /* Generate sg_table for kmap buffers */
> + ret = ti_qspi_map_buf(qspi, buf, msg->len, &sgt);
> + if (ret)
> + goto err_unlock;
> + ret = dma_map_sg(dev, sgt.sgl, sgt.nents,
> + DMA_FROM_DEVICE);
> + if (!ret) {
> + ret = -ENOMEM;
> + goto err_unlock;
> + }
> + ret = ti_qspi_dma_xfer_sg(qspi, sgt, msg->from);
> + dma_unmap_sg(dev, sgt.sgl, sgt.orig_nents,
> + DMA_FROM_DEVICE);
> + sg_free_table(&sgt);
> +#endif
> + } else {
> + dev_err(qspi->dev, "Invalid address for DMA\n");
> + ret = -EIO;
> + goto err_unlock;
> + }
> + } else {
> + memcpy_fromio(msg->buf, qspi->mmap_base + msg->from, msg->len);
> + }
> msg->retlen = msg->len;
>
> +err_unlock:
> mutex_unlock(&qspi->list_lock);
>
> return ret;
> @@ -536,6 +678,7 @@ static int ti_qspi_probe(struct platform_device *pdev)
> struct device_node *np = pdev->dev.of_node;
> u32 max_freq;
> int ret = 0, num_cs, irq;
> + dma_cap_mask_t mask;
>
> master = spi_alloc_master(&pdev->dev, sizeof(*qspi));
> if (!master)
> @@ -550,6 +693,7 @@ static int ti_qspi_probe(struct platform_device *pdev)
> master->dev.of_node = pdev->dev.of_node;
> master->bits_per_word_mask = SPI_BPW_MASK(32) | SPI_BPW_MASK(16) |
> SPI_BPW_MASK(8);
> + master->spi_flash_read = ti_qspi_spi_flash_read;
>
> if (!of_property_read_u32(np, "num-cs", &num_cs))
> master->num_chipselect = num_cs;
> @@ -592,17 +736,6 @@ static int ti_qspi_probe(struct platform_device *pdev)
> goto free_master;
> }
>
> - if (res_mmap) {
> - qspi->mmap_base = devm_ioremap_resource(&pdev->dev,
> - res_mmap);
> - master->spi_flash_read = ti_qspi_spi_flash_read;
> - if (IS_ERR(qspi->mmap_base)) {
> - dev_err(&pdev->dev,
> - "falling back to PIO mode\n");
> - master->spi_flash_read = NULL;
> - }
> - }
> - qspi->mmap_enabled = false;
>
> if (of_property_read_bool(np, "syscon-chipselects")) {
> qspi->ctrl_base =
> @@ -637,6 +770,33 @@ static int ti_qspi_probe(struct platform_device *pdev)
> if (ret)
> goto free_master;
>
> + dma_cap_zero(mask);
> + dma_cap_set(DMA_MEMCPY, mask);
> +
> + qspi->rx_chan = dma_request_channel(mask, NULL, NULL);
dma_request_channel is deprecated, please use the:
dma_request_chan_by_mask()
> + if (!qspi->rx_chan) {
> + dev_err(qspi->dev,
> + "No Rx DMA available, trying mmap mode\n");
> + ret = 0;
> + goto no_dma;
> + }
> + master->dma_rx = qspi->rx_chan;
> + init_completion(&qspi->transfer_complete);
> + if (res_mmap)
> + qspi->mmap_phys_base = (dma_addr_t)res_mmap->start;
> +
> +no_dma:
> + if (!qspi->rx_chan && res_mmap) {
> + qspi->mmap_base = devm_ioremap_resource(&pdev->dev, res_mmap);
> + if (IS_ERR(qspi->mmap_base)) {
> + dev_info(&pdev->dev,
> + "mmap failed with error %ld using PIO mode\n",
> + PTR_ERR(qspi->mmap_base));
> + qspi->mmap_base = NULL;
> + master->spi_flash_read = NULL;
> + }
> + }
> + qspi->mmap_enabled = false;
> return 0;
>
> free_master:
> @@ -656,6 +816,9 @@ static int ti_qspi_remove(struct platform_device *pdev)
> pm_runtime_put_sync(&pdev->dev);
> pm_runtime_disable(&pdev->dev);
>
> + if (qspi->rx_chan)
> + dma_release_channel(qspi->rx_chan);
> +
> return 0;
> }
>
>
--
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