Re: [PATCH 2/6] dmaengine: Add driver for TI DMA crossbar on DRA7x
From: Peter Ujfalusi
Date: Mon Mar 02 2015 - 02:58:51 EST
On 02/28/2015 06:00 PM, Paul Bolle wrote:
> On Tue, 2015-02-24 at 16:21 +0200, Peter Ujfalusi wrote:
>> The DRA7x has more peripherals with DMA requests than the sDMA can handle:
>> 205 vs 127. All DMA requests are routed through the DMA crossbar, which can
>> be configured to route selected incoming DMA requests to specific sDMA
>> request.
>>
>> Signed-off-by: Peter Ujfalusi <peter.ujfalusi@xxxxxx>
>> ---
>> drivers/dma/Kconfig | 4 +
>> drivers/dma/Makefile | 1 +
>> drivers/dma/ti-dma-crossbar.c | 191 ++++++++++++++++++++++++++++++++++++++++++
>> 3 files changed, 196 insertions(+)
>> create mode 100644 drivers/dma/ti-dma-crossbar.c
>
> A simple observation follows.
>
>> diff --git a/drivers/dma/Kconfig b/drivers/dma/Kconfig
>> index a874b6ec6650..dfe72a0f46dc 100644
>> --- a/drivers/dma/Kconfig
>> +++ b/drivers/dma/Kconfig
>> @@ -245,6 +245,9 @@ config TI_EDMA
>> Enable support for the TI EDMA controller. This DMA
>> engine is found on TI DaVinci and AM33xx parts.
>>
>> +config TI_DMA_CROSSBAR
>> + bool
>> +
>
> This is a bool symbol...
>
>> config ARCH_HAS_ASYNC_TX_FIND_CHANNEL
>> bool
>>
>> @@ -330,6 +333,7 @@ config DMA_OMAP
>> depends on ARCH_OMAP
>> select DMA_ENGINE
>> select DMA_VIRTUAL_CHANNELS
>> + select TI_DMA_CROSSBAR if SOC_DRA7XX
>>
>> config DMA_BCM2835
>> tristate "BCM2835 DMA engine support"
>> diff --git a/drivers/dma/Makefile b/drivers/dma/Makefile
>> index f915f61ec574..bc12f9a4e62b 100644
>> --- a/drivers/dma/Makefile
>> +++ b/drivers/dma/Makefile
>> @@ -38,6 +38,7 @@ obj-$(CONFIG_EP93XX_DMA) += ep93xx_dma.o
>> obj-$(CONFIG_DMA_SA11X0) += sa11x0-dma.o
>> obj-$(CONFIG_MMP_TDMA) += mmp_tdma.o
>> obj-$(CONFIG_DMA_OMAP) += omap-dma.o
>> +obj-$(CONFIG_TI_DMA_CROSSBAR) += ti-dma-crossbar.o
>
> ... so this file will be either not built or built into the kernel...
>
>> obj-$(CONFIG_DMA_BCM2835) += bcm2835-dma.o
>> obj-$(CONFIG_MMP_PDMA) += mmp_pdma.o
>> obj-$(CONFIG_DMA_JZ4740) += dma-jz4740.o
>> diff --git a/drivers/dma/ti-dma-crossbar.c b/drivers/dma/ti-dma-crossbar.c
>> new file mode 100644
>> index 000000000000..bf01434df46a
>> --- /dev/null
>> +++ b/drivers/dma/ti-dma-crossbar.c
>> @@ -0,0 +1,191 @@
>> +/*
>> + * Copyright (C) 2015 Texas Instruments Incorporated - http://www.ti.com
>> + * Author: Peter Ujfalusi <peter.ujfalusi@xxxxxx>
>> + *
>> + * 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.
>> + *
>> + */
>> +#include <linux/slab.h>
>> +#include <linux/err.h>
>> +#include <linux/init.h>
>> +#include <linux/list.h>
>> +#include <linux/io.h>
>> +#include <linux/regmap.h>
>> +#include <linux/idr.h>
>> +#include <linux/of_address.h>
>> +#include <linux/of_device.h>
>> +#include <linux/of_dma.h>
>> +#include <linux/module.h>
>
> ... this includes linux/module.h ...
>
> [...]
>
>> +static struct platform_driver ti_dma_xbar_driver = {
>> + .probe = ti_dma_xbar_probe,
>> + .driver = {
>> + .name = "ti-dma-crossbar",
>> + .owner = THIS_MODULE,
>
> ... is that needed to make this work?
>
>> + .of_match_table = of_match_ptr(ti_dma_xbar_match),
>> + },
>> +};
>> +
>> +int omap_dmaxbar_init(void)
>> +{
>> + return platform_driver_register(&ti_dma_xbar_driver);
>> +}
>> +arch_initcall(omap_dmaxbar_init);
>> +
>> +MODULE_DESCRIPTION("TI DMA Crossbar");
>> +MODULE_AUTHOR("Peter Ujfalusi <peter.ujfalusi@xxxxxx>");
>> +MODULE_LICENSE("GPL");
>
> And why are these three macros needed?
>
> By the way: there's a mismatch between the header (which is GPL v2) and
> the MODULE_LICENSE() string (which means GPL v2 or later).
True, the linux/module.h and the lines with *MODULE* in it is not needed in
case the driver will be not built as module. I have not really thought about
this to be honest, I have had these macros in most (all?) of the drivers I wrote.
They will be gone in V2 of the series.
Thanks,
PÃter
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