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>
---
drivers/spi/spi-ti-qspi.c | 132 +++++++++++++++++++++++++++++++++++++++++-----
1 file changed, 120 insertions(+), 12 deletions(-)
diff --git a/drivers/spi/spi-ti-qspi.c b/drivers/spi/spi-ti-qspi.c
index eac3c960b2de..1f6a11a45891 100644
--- a/drivers/spi/spi-ti-qspi.c
+++ b/drivers/spi/spi-ti-qspi.c
@@ -41,6 +41,8 @@ struct ti_qspi_regs {
};
struct ti_qspi {
+ struct completion transfer_complete;
+
/* list synchronization */
struct mutex list_lock;
@@ -54,6 +56,9 @@ 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;
@@ -377,6 +382,78 @@ static int qspi_transfer_msg(struct ti_qspi *qspi, struct spi_transfer *t)
return 0;
}
+static void qspi_dma_callback(void *param)
+{
+ struct ti_qspi *qspi = param;
+
+ complete(&qspi->transfer_complete);
+}
+
+static int qspi_dma_transfer(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 = NULL;
+ 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");
+ ret = -EIO;
+ goto err;
+ }
+
+ tx->callback = 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);
+ goto err;
+ }
+
+ dma_async_issue_pending(chan);
+ ret = wait_for_completion_timeout(&qspi->transfer_complete,
+ msecs_to_jiffies(len));
+ if (ret <= 0) {
+ dmaengine_terminate_all(chan);
+ dev_err(qspi->dev, "DMA wait_for_completion_timeout\n");
+ if (!ret)
+ ret = -ETIMEDOUT;
+ goto err;
+ }
+
+ ret = 0;
+
+err:
+ return ret;
+}
+
+static int qspi_dma_sg(struct ti_qspi *qspi,
+ struct spi_flash_read_message *msg)
+{
+ struct scatterlist *sg;
+ dma_addr_t dma_src = qspi->mmap_phys_base + msg->from;
+ dma_addr_t dma_dst;
+ int i, len, ret = 0;
+
+ for_each_sg(msg->rx_sg.sgl, sg, msg->rx_sg.nents, i) {
+ dma_dst = sg_dma_address(sg);
+ len = sg_dma_len(sg);
+ ret = qspi_dma_transfer(qspi, dma_dst, dma_src, len);
+ if (ret != 0)
+ return ret;
+ dma_src += len;
+ }
+
+ return ret;
+}
+
static void ti_qspi_enable_memory_map(struct spi_device *spi)
{
struct ti_qspi *qspi = spi_master_get_devdata(spi->master);
@@ -435,9 +512,17 @@ 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) {
+ ret = qspi_dma_sg(qspi, msg);
+ if (ret != 0)
+ goto err;
+ } else {
+ memcpy_fromio(msg->buf, qspi->mmap_base + msg->from, msg->len);
+ }
msg->retlen = msg->len;
+err:
mutex_unlock(&qspi->list_lock);
return ret;
@@ -525,6 +610,7 @@ 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)
@@ -539,6 +625,7 @@ 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;
@@ -581,17 +668,6 @@ 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 =
@@ -626,6 +702,33 @@ 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);
+ 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:
@@ -635,9 +738,14 @@ free_master:
static int ti_qspi_remove(struct platform_device *pdev)
{
+ struct ti_qspi *qspi = platform_get_drvdata(pdev);
+
pm_runtime_put_sync(&pdev->dev);
pm_runtime_disable(&pdev->dev);
+ if (qspi->rx_chan)
+ dma_release_channel(qspi->rx_chan);
+
return 0;
}
--
2.8.0
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