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@xxxxxx>
---
v5: Move setting up DMA channel to before driver registration.
v4: use dma_request_chan_by_mask() and fix build warnings.
v3: Cleanup code based on review comments for v2.
v2: Handle kmap'd buffers of JFFS2 FS
drivers/spi/spi-ti-qspi.c | 195 ++++++++++++++++++++++++++++++++++++++++++----
1 file changed, 178 insertions(+), 17 deletions(-)
diff --git a/drivers/spi/spi-ti-qspi.c b/drivers/spi/spi-ti-qspi.c
index ac0b072815a3..d9c51ee848ec 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 +542,45 @@ 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) {
+ 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)msg->buf >= PKMAP_BASE &&
+ (unsigned long)msg->buf < (PKMAP_BASE +
+ (LAST_PKMAP * PAGE_SIZE))) {
+ struct device *dev = qspi->rx_chan->device->dev;
+ struct sg_table sgt;
+
+ /* Generate sg_table for kmap buffers */
+ ret = ti_qspi_map_buf(qspi, msg->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 +677,7 @@ 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 +692,7 @@ 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 +735,6 @@ 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 =
@@ -633,11 +765,37 @@ static int ti_qspi_probe(struct platform_device *pdev)
if (!of_property_read_u32(np, "spi-max-frequency", &max_freq))
qspi->spi_max_frequency = max_freq;
- ret = devm_spi_register_master(&pdev->dev, master);
- if (ret)
- goto free_master;
+ dma_cap_zero(mask);
+ dma_cap_set(DMA_MEMCPY, mask);
- return 0;
+ qspi->rx_chan = dma_request_chan_by_mask(&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;
+
+ ret = devm_spi_register_master(&pdev->dev, master);
+ if (!ret)
+ return 0;
free_master:
spi_master_put(master);
@@ -656,6 +814,9 @@ 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;
}
--
2.9.2
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