[5/5] RFC spi: sun4i: add DMA support

Message ID	ba0d6eb37cc4b0d2c46acbf9fcd7d644b3545ce8.1464130597.git.hramrach@gmail.com (mailing list archive)
State	New, archived
Headers	show Return-Path: <linux-arm-kernel-bounces+patchwork-linux-arm=patchwork.kernel.org@lists.infradead.org> Date: 26 May 2016 19:25:25 -0000 MBOX-Line: From ba0d6eb37cc4b0d2c46acbf9fcd7d644b3545ce8 Mon Sep 17 00:00:00 2001 Message-Id: <ba0d6eb37cc4b0d2c46acbf9fcd7d644b3545ce8.1464130597.git.hramrach@gmail.com> From: Michal Suchanek <hramrach@gmail.com> In-Reply-To: <cover.1464130597.git.hramrach@gmail.com> References: <cover.1464130597.git.hramrach@gmail.com> Subject: [PATCH 5/5] RFC spi: sun4i: add DMA support MIME-Version: 1.0 To: linux-sunxi@googlegroups.com, Mark Brown <broonie@kernel.org>, Maxime Ripard <maxime.ripard@free-electrons.com>, Chen-Yu Tsai <wens@csie.org>, linux-spi@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, Precedence: list Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: base64 Sender: "linux-arm-kernel" <linux-arm-kernel-bounces@lists.infradead.org> Errors-To: linux-arm-kernel-bounces+patchwork-linux-arm=patchwork.kernel.org@lists.infradead.org

diff --git a/drivers/spi/spi-sun4i.c b/drivers/spi/spi-sun4i.c index e1a75dd6..ed2269c 100644 --- a/drivers/spi/spi-sun4i.c +++ b/drivers/spi/spi-sun4i.c @@ -14,6 +14,8 @@ #include <linux/clk.h> #include <linux/delay.h> #include <linux/device.h> +#include <linux/dmaengine.h> +#include <linux/dma-mapping.h> #include <linux/interrupt.h> #include <linux/io.h> #include <linux/module.h> @@ -34,6 +36,7 @@ #define SUN4I_CTL_CPHA BIT(2) #define SUN4I_CTL_CPOL BIT(3) #define SUN4I_CTL_CS_ACTIVE_LOW BIT(4) +#define SUN4I_CTL_DMAMC_DEDICATED BIT(5) #define SUN4I_CTL_LMTF BIT(6) #define SUN4I_CTL_TF_RST BIT(8) #define SUN4I_CTL_RF_RST BIT(9) @@ -51,6 +54,8 @@ #define SUN4I_INT_STA_REG 0x10 #define SUN4I_DMA_CTL_REG 0x14 +#define SUN4I_DMA_CTL_RF_READY BIT(0) +#define SUN4I_DMA_CTL_TF_NOT_FULL BIT(10) #define SUN4I_WAIT_REG 0x18 @@ -130,6 +135,13 @@ static inline void sun4i_spi_fill_fifo(struct sun4i_spi *sspi, int len) } } +static bool sun4i_spi_can_dma(struct spi_master *master, + struct spi_device *spi, + struct spi_transfer *tfr) +{ + return tfr->len >= SUN4I_FIFO_DEPTH; +} + static void sun4i_spi_set_cs(struct spi_device *spi, bool enable) { struct sun4i_spi *sspi = spi_master_get_devdata(spi->master); @@ -177,17 +189,20 @@ static int sun4i_spi_transfer_one(struct spi_master *master, struct spi_transfer *tfr) { struct sun4i_spi *sspi = spi_master_get_devdata(master); + struct dma_async_tx_descriptor *desc_tx = NULL, *desc_rx = NULL; unsigned int mclk_rate, div, timeout; unsigned int start, end, tx_time; unsigned int tx_len = 0; + u32 reg, trigger = 0; int ret = 0; - u32 reg; - /* We don't support transfer larger than the FIFO */ - if (tfr->len > SUN4I_FIFO_DEPTH) - return -EMSGSIZE; - if (tfr->tx_buf && tfr->len >= SUN4I_FIFO_DEPTH) - return -EMSGSIZE; + if (!master->can_dma) { + /* We don't support transfer larger than the FIFO */ + if (tfr->len > SUN4I_FIFO_DEPTH) + return -EMSGSIZE; + if (tfr->tx_buf && tfr->len >= SUN4I_FIFO_DEPTH) + return -EMSGSIZE; + } reinit_completion(&sspi->done); sspi->tx_buf = tfr->tx_buf; @@ -277,14 +292,67 @@ static int sun4i_spi_transfer_one(struct spi_master *master, sun4i_spi_write(sspi, SUN4I_BURST_CNT_REG, SUN4I_BURST_CNT(tfr->len)); sun4i_spi_write(sspi, SUN4I_XMIT_CNT_REG, SUN4I_XMIT_CNT(tx_len)); - /* Fill the TX FIFO */ - /* Filling the FIFO fully causes timeout for some reason - * at least on spi2 on A10s */ - sun4i_spi_fill_fifo(sspi, SUN4I_FIFO_DEPTH - 1); - /* Enable the interrupts */ sun4i_spi_write(sspi, SUN4I_INT_CTL_REG, SUN4I_INT_CTL_TC); + if (sun4i_spi_can_dma(master, spi, tfr)) { + dev_dbg(&sspi->master->dev, "Using DMA mode for transfer\n"); + + if (sspi->tx_buf) { + desc_tx = dmaengine_prep_slave_sg(master->dma_tx, + tfr->tx_sg.sgl, tfr->tx_sg.nents, + DMA_TO_DEVICE, + DMA_PREP_INTERRUPT | DMA_CTRL_ACK); + if (!desc_tx) { + dev_err(&sspi->master->dev, + "Couldn't prepare dma slave\n"); + return -EIO; + } + + trigger |= SUN4I_DMA_CTL_TF_NOT_FULL; + + dmaengine_submit(desc_tx); + dma_async_issue_pending(master->dma_tx); + + } + + if (sspi->rx_buf) { + desc_rx = dmaengine_prep_slave_sg(master->dma_rx, + tfr->rx_sg.sgl, tfr->rx_sg.nents, + DMA_FROM_DEVICE, + DMA_PREP_INTERRUPT | DMA_CTRL_ACK); + if (!desc_rx) { + dev_err(&sspi->master->dev, + "Couldn't prepare dma slave\n"); + return -EIO; + } + + trigger |= SUN4I_DMA_CTL_RF_READY; + + dmaengine_submit(desc_rx); + dma_async_issue_pending(master->dma_rx); + } + + /* Enable Dedicated DMA requests */ + reg = sun4i_spi_read(sspi, SUN4I_CTL_REG); + reg |= SUN4I_CTL_DMAMC_DEDICATED; + sun4i_spi_write(sspi, SUN4I_CTL_REG, reg); + sun4i_spi_write(sspi, SUN4I_DMA_CTL_REG, trigger); + } else { + dev_dbg(&sspi->master->dev, "Using PIO mode for transfer\n"); + + /* Disable DMA requests */ + reg = sun4i_spi_read(sspi, SUN4I_CTL_REG); + sun4i_spi_write(sspi, SUN4I_CTL_REG, + reg & ~SUN4I_CTL_DMAMC_DEDICATED); + sun4i_spi_write(sspi, SUN4I_DMA_CTL_REG, 0); + + /* Fill the TX FIFO */ + /* Filling the FIFO fully causes timeout for some reason + * at least on spi2 on A10s */ + sun4i_spi_fill_fifo(sspi, SUN4I_FIFO_DEPTH - 1); + } + /* Start the transfer */ reg = sun4i_spi_read(sspi, SUN4I_CTL_REG); sun4i_spi_write(sspi, SUN4I_CTL_REG, reg | SUN4I_CTL_XCH); @@ -304,7 +372,16 @@ static int sun4i_spi_transfer_one(struct spi_master *master, goto out; } - sun4i_spi_drain_fifo(sspi, SUN4I_FIFO_DEPTH); + if (sun4i_spi_can_dma(master, spi, tfr) && desc_rx) { + /* The receive transfer should be the last one to finish */ + /* This seems to work OK. + * TODO: look for some drivers which do something + * more sensible here. */ + dma_wait_for_async_tx(desc_rx); + } else { + /* This should be noop with tx only dma */ + sun4i_spi_drain_fifo(sspi, SUN4I_FIFO_DEPTH); + } out: sun4i_spi_write(sspi, SUN4I_INT_CTL_REG, 0); @@ -369,6 +446,7 @@ static int sun4i_spi_runtime_suspend(struct device *dev) static int sun4i_spi_probe(struct platform_device *pdev) { + struct dma_slave_config dma_sconfig; struct spi_master *master; struct sun4i_spi *sspi; struct resource *res; @@ -404,6 +482,7 @@ static int sun4i_spi_probe(struct platform_device *pdev) goto err_free_master; } + init_completion(&sspi->done); sspi->master = master; master->max_speed_hz = 100*1000*1000; master->min_speed_hz = 3*1000; @@ -430,8 +509,55 @@ static int sun4i_spi_probe(struct platform_device *pdev) goto err_free_master; } - init_completion(&sspi->done); + master->dma_tx = dma_request_slave_channel_reason(&pdev->dev, "tx"); + if (IS_ERR(master->dma_tx)) { + dev_err(&pdev->dev, "Unable to acquire DMA channel TX\n"); + ret = PTR_ERR(master->dma_tx); + master->dma_tx = NULL; + goto wakeup; + } + + dma_sconfig.direction = DMA_MEM_TO_DEV; + dma_sconfig.src_addr_width = DMA_SLAVE_BUSWIDTH_1_BYTE; + dma_sconfig.dst_addr_width = DMA_SLAVE_BUSWIDTH_1_BYTE; + dma_sconfig.dst_addr = res->start + SUN4I_TXDATA_REG; + dma_sconfig.src_maxburst = 1; + dma_sconfig.dst_maxburst = 1; + ret = dmaengine_slave_config(master->dma_tx, &dma_sconfig); + if (ret) { + dev_err(&pdev->dev, "Unable to configure TX DMA slave\n"); + goto err_tx_dma_release; + } + + master->dma_rx = dma_request_slave_channel_reason(&pdev->dev, "rx"); + if (IS_ERR(master->dma_rx)) { + dev_err(&pdev->dev, "Unable to acquire DMA channel RX\n"); + ret = PTR_ERR(master->dma_rx); + goto err_tx_dma_release; + } + + dma_sconfig.direction = DMA_DEV_TO_MEM; + dma_sconfig.src_addr_width = DMA_SLAVE_BUSWIDTH_1_BYTE; + dma_sconfig.dst_addr_width = DMA_SLAVE_BUSWIDTH_1_BYTE; + dma_sconfig.src_addr = res->start + SUN4I_RXDATA_REG; + dma_sconfig.src_maxburst = 1; + dma_sconfig.dst_maxburst = 1; + + ret = dmaengine_slave_config(master->dma_rx, &dma_sconfig); + if (ret) { + dev_err(&pdev->dev, "Unable to configure RX DMA slave\n"); + goto err_rx_dma_release; + } + + /* This is a bit dodgy. If you set can_dma then map_msg in spi.c + * apparently dereferences your dma channels if non-NULL even if your + * can_dma never returns true (and crashes if the channel is an error + * pointer). So just don't set can_dma unless both channels are valid. + */ + master->can_dma = sun4i_spi_can_dma; + master->max_transfer_size = NULL; /* no known limit */ +wakeup: /* * This wake-up/shutdown pattern is to be able to have the * device woken up, even if runtime_pm is disabled @@ -454,18 +580,37 @@ static int sun4i_spi_probe(struct platform_device *pdev) return 0; +err_rx_dma_release: + dma_release_channel(master->dma_rx); +err_tx_dma_release: + dma_release_channel(master->dma_tx); + master->dma_tx = NULL; + master->dma_rx = NULL; + goto wakeup; + err_pm_disable: pm_runtime_disable(&pdev->dev); sun4i_spi_runtime_suspend(&pdev->dev); err_free_master: + if (master->can_dma) { + dma_release_channel(master->dma_rx); + dma_release_channel(master->dma_tx); + } spi_master_put(master); return ret; } static int sun4i_spi_remove(struct platform_device *pdev) { + struct spi_master *master = platform_get_drvdata(pdev); + pm_runtime_disable(&pdev->dev); + if (master->can_dma) { + dma_release_channel(master->dma_rx); + dma_release_channel(master->dma_tx); + } + return 0; }

[5/5] RFC spi: sun4i: add DMA support

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