[PATCH 1/5] dmaengine: mxs-dma: add dma support for i.MX23/28
From: Lothar Waßmann <hidden>
Date: 2011-02-07 07:37:14
Hi, Shawn Guo writes:
quoted hunk ↗ jump to hunk
This patch adds dma support for Freescale MXS-based SoC i.MX23/28, including apbh-dma and apbx-dma. * apbh-dma and apbx-dma are supported in the driver as two instances, and have to be filtered by dma clients via device id. It becomes the convention that apbh-dma always gets registered prior to apbx-dma. * apbh-dma is different between mx23 and mx28, hardware version register is used to handle the differences. * Every the mxs dma channel is statically assigned to client device by soc design with fixed irq. The irq number is being passed by alloc_chan function with mxs_dma_data, and client driver has to filter the correct channel by its channel id. * mxs-dma supports pio function besides data transfer. The driver uses dma_data_direction DMA_NONE to identify the pio mode, and steals sgl and sg_len to get pio words and numbers from clients. * mxs dmaengine has some very specific features, like sense function and the special NAND support (nand_lock, nand_wait4ready). These are too specific to implemented in generic dmaengine driver. * The parameter "flags" of prep functions is currently being used to pass wait4end flag from clients. * The driver refers to imx-sdma and only a single descriptor is statically assigned to each channel. Signed-off-by: Shawn Guo <redacted> --- arch/arm/mach-mxs/include/mach/dma.h | 16 + drivers/dma/Kconfig | 8 + drivers/dma/Makefile | 1 + drivers/dma/mxs-dma.c | 702 ++++++++++++++++++++++++++++++++++ 4 files changed, 727 insertions(+), 0 deletions(-) create mode 100644 arch/arm/mach-mxs/include/mach/dma.h create mode 100644 drivers/dma/mxs-dma.cdiff --git a/arch/arm/mach-mxs/include/mach/dma.h b/arch/arm/mach-mxs/include/mach/dma.h new file mode 100644 index 0000000..429f431 --- /dev/null +++ b/arch/arm/mach-mxs/include/mach/dma.h@@ -0,0 +1,16 @@ +/* + * Copyright 2011 Freescale Semiconductor, Inc. All Rights Reserved. + * + * This program is free software; you can redistribute it and/or modify + * it under the terms of the GNU General Public License version 2 as + * published by the Free Software Foundation. + */ + +#ifndef __MACH_MXS_DMA_H__ +#define __MACH_MXS_DMA_H__ + +struct mxs_dma_data { + int chan_irq; +}; + +#endif /* __MACH_MXS_DMA_H__ */diff --git a/drivers/dma/Kconfig b/drivers/dma/Kconfig index 1c28816..0b9a5b1 100644 --- a/drivers/dma/Kconfig +++ b/drivers/dma/Kconfig@@ -227,6 +227,14 @@ config IMX_DMA Support the i.MX DMA engine. This engine is integrated into Freescale i.MX1/21/27 chips. +config MXS_DMA + tristate "MXS DMA support"
Does it make any sense to build this driver as a module, given the fact that it does not even support to be removed?
+ depends on SOC_IMX23 || SOC_MX28
SOC_IMX28?
quoted hunk ↗ jump to hunk
diff --git a/drivers/dma/mxs-dma.c b/drivers/dma/mxs-dma.c new file mode 100644 index 0000000..8d1e811 --- /dev/null +++ b/drivers/dma/mxs-dma.c@@ -0,0 +1,702 @@
[...]
+struct mxs_dma_engine {
+ struct device *dev;
+ int dev_id;
+ unsigned int version;
+ void __iomem *base;
+ struct clk *clk;
+ struct dma_device dma_device;
+ struct device_dma_parameters dma_parms;^^^^ mixed space/tab indentation. [...]
+static int mxs_dma_control(struct dma_chan *chan, enum dma_ctrl_cmd cmd,
+ unsigned long arg)
+{
+ struct mxs_dma_chan *mxs_chan = to_mxs_dma_chan(chan);
+
+ switch (cmd) {
+ case DMA_TERMINATE_ALL:
+ mxs_dma_disable_chan(mxs_chan);
+ return 0;
+ case DMA_PAUSE:
+ mxs_dma_pause_chan(mxs_chan);
+ return 0;
+ case DMA_RESUME:
+ mxs_dma_resume_chan(mxs_chan);
+ return 0;
+ default:
+ return -ENOSYS;
+ }
+
+ return -EINVAL; ^^^^^^^^^^^^^^
This can never be reached. IMO:
| int ret = 0;
| switch(cmd) {
| case DMA_TERMINATE_ALL:
| mxs_dma_disable_chan(mxs_chan);
| break;
| case DMA_PAUSE:
| mxs_dma_pause_chan(mxs_chan);
| break;
| case DMA_RESUME:
| mxs_dma_resume_chan(mxs_chan);
| break;
| default:
| ret = -ENOSYS;
| }
|
| return ret;
would be cleaner (and effectively generates the same code).
Lothar Wa?mann
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