Re: [PATCH v4 3/8] dmaengine: Add driver for TI DMA crossbar on DRA7x

[Maxime Ripard <maxime.ripard@free-electrons.com>]

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Hi,

On Wed, Apr 08, 2015 at 04:14:47PM +0300, 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@ti.com>
> ---
>  drivers/dma/Kconfig           |   4 +
>  drivers/dma/Makefile          |   1 +
>  drivers/dma/ti-dma-crossbar.c | 185 ++++++++++++++++++++++++++++++++++++++++++
>  3 files changed, 190 insertions(+)
>  create mode 100644 drivers/dma/ti-dma-crossbar.c
> 
> diff --git a/drivers/dma/Kconfig b/drivers/dma/Kconfig
> index 91eced044321..33a7401597be 100644
> --- a/drivers/dma/Kconfig
> +++ b/drivers/dma/Kconfig
> @@ -234,6 +234,9 @@ 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
> +
>  config ARCH_HAS_ASYNC_TX_FIND_CHANNEL
>  	bool
>  
> @@ -319,6 +322,7 @@ 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 7e8301cb489d..19ac70b8af0a 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-$(CONFIG_TI_DMA_CROSSBAR) += ti-dma-crossbar.o
>  obj-$(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..5cb1eb7e86d2
> --- /dev/null
> +++ b/drivers/dma/ti-dma-crossbar.c
> @@ -0,0 +1,185 @@
> +/*
> + *  Copyright (C) 2015 Texas Instruments Incorporated - http://www.ti.com
> + *  Author: Peter Ujfalusi <peter.ujfalusi@ti.com>
> + *
> + * 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/idr.h>
> +#include <linux/of_address.h>
> +#include <linux/of_device.h>
> +#include <linux/of_dma.h>
> +
> +#define TI_XBAR_OUTPUTS	127
> +#define TI_XBAR_INPUTS	256
> +
> +static DEFINE_IDR(map_idr);
> +
> +struct ti_dma_xbar_data {
> +	void __iomem *iomem;
> +
> +	struct dma_router dmarouter;
> +
> +	uint safe_val; /* Value to rest the crossbar lines */
> +	uint xbar_requests; /* number of DMA requests connected to XBAR */
> +	uint dma_requests; /* number of DMA requests forwarded to DMA */
> +};
> +
> +struct ti_dma_xbar_map {
> +	int xbar_in;
> +	int xbar_out;
> +};
> +
> +static inline void ti_dma_xbar_write(void __iomem *iomem, int xbar, int val)
> +{
> +	writew_relaxed(val, iomem + (xbar * 2));

Silently casting val (an integer) to a u16 isn't really nice I
guess. At least you could be upfront about it in the prototype.

> +}
> +
> +static void ti_dma_xbar_free(struct device *dev, void *route_data)
> +{
> +	struct ti_dma_xbar_data *xbar = dev_get_drvdata(dev);
> +	struct ti_dma_xbar_map *map = route_data;
> +
> +	dev_dbg(dev, "Unmapping XBAR%d (was routed to %d)\n",
> +		map->xbar_in, map->xbar_out);
> +
> +	ti_dma_xbar_write(xbar->iomem, map->xbar_out, xbar->safe_val);
> +	idr_remove(&map_idr, map->xbar_out);
> +	kfree(map);
> +}
> +
> +static void *ti_dma_xbar_route_allocate(struct of_phandle_args *dma_spec,
> +					struct of_dma *ofdma)
> +{
> +	struct platform_device *pdev = of_find_device_by_node(ofdma->of_node);
> +	struct ti_dma_xbar_data *xbar = platform_get_drvdata(pdev);
> +	struct ti_dma_xbar_map *map;
> +
> +	if (dma_spec->args[0] >= xbar->xbar_requests) {
> +		dev_err(&pdev->dev, "Invalid XBAR request number: %d\n",
> +			dma_spec->args[0]);
> +		return NULL;
> +	}
> +
> +	dma_spec->np = of_parse_phandle(ofdma->of_node, "dma-masters", 0);
> +	if (!dma_spec->np) {
> +		dev_err(&pdev->dev, "Can't get DMA master\n");
> +		return NULL;
> +	}
> +
> +	map = kzalloc(sizeof(*map), GFP_KERNEL);
> +	if (!map)
> +		return NULL;

You're leaking dma_spec->np.

> +
> +	map->xbar_out = idr_alloc(&map_idr, NULL, 0, xbar->dma_requests,
> +				  GFP_KERNEL);
> +	map->xbar_in = dma_spec->args[0];
> +
> +	/* The DMA request is 1 based in sDMA */
> +	dma_spec->args[0] = map->xbar_out + 1;
> +
> +	dev_dbg(&pdev->dev, "Mapping XBAR%d to DMA%d\n",
> +		map->xbar_in, map->xbar_out);
> +
> +	ti_dma_xbar_write(xbar->iomem, map->xbar_out, map->xbar_in);
> +
> +	return map;
> +}
> +
> +static int ti_dma_xbar_probe(struct platform_device *pdev)
> +{
> +	struct device_node *node = pdev->dev.of_node;
> +	struct device_node *dma_node;
> +	struct ti_dma_xbar_data *xbar;
> +	struct resource *res;
> +	void __iomem *iomem;
> +	int i, ret;
> +
> +	if (!node)
> +		return -ENODEV;
> +
> +	dma_node = of_parse_phandle(node, "dma-masters", 0);
> +	if (!dma_node) {
> +		dev_err(&pdev->dev, "Can't get DMA master node\n");
> +		return -ENODEV;
> +	}
> +
> +	xbar = devm_kzalloc(&pdev->dev, sizeof(*xbar), GFP_KERNEL);
> +	if (!xbar)
> +		return -ENOMEM;

And here too.

> +	if (of_property_read_u32(dma_node, "dma-requests",
> +				 &xbar->dma_requests)) {
> +		dev_info(&pdev->dev,
> +			 "Missing XBAR output information, using %u.\n",
> +			 TI_XBAR_OUTPUTS);
> +		xbar->dma_requests = TI_XBAR_OUTPUTS;
> +	}
> +	of_node_put(dma_node);
> +
> +	if (of_property_read_u32(node, "dma-requests", &xbar->xbar_requests)) {
> +		dev_info(&pdev->dev,
> +			 "Missing XBAR input information, using %u.\n",
> +			 TI_XBAR_INPUTS);
> +		xbar->xbar_requests = TI_XBAR_INPUTS;
> +	}
> +
> +	if (of_property_read_u32(node, "ti,dma-safe-map", &xbar->safe_val))
> +		xbar->safe_val = 0;
> +
> +	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
> +	if (!res)
> +		return -ENODEV;
> +
> +	if (!devm_request_mem_region(&pdev->dev, res->start, resource_size(res),
> +				     dev_name(&pdev->dev)))
> +		return -ENODEV;
> +
> +	iomem = devm_ioremap(&pdev->dev, res->start, resource_size(res));
> +	if (!iomem)
> +		return -ENOMEM;

You can use devm_ioremap_resource here.

> +	xbar->iomem = iomem;
> +
> +	xbar->dmarouter.dev = &pdev->dev;
> +	xbar->dmarouter.route_free = ti_dma_xbar_free;
> +
> +	platform_set_drvdata(pdev, xbar);
> +
> +	ret = of_dma_router_register(node, ti_dma_xbar_route_allocate,
> +				     &xbar->dmarouter);
> +	if (ret)
> +		return -ENODEV;

Starting here, I'd expect that your driver can be used....

> +
> +	/* Reset the crossbar */
> +	for (i = 0; i < xbar->dma_requests; i++)
> +		ti_dma_xbar_write(xbar->iomem, i, xbar->safe_val);

... however, the hardware doesn't seem ready. Isn't it a race?


> +	return 0;
> +}
> +
> +static const struct of_device_id ti_dma_xbar_match[] = {
> +	{ .compatible = "ti,dra7-dma-crossbar" },
> +	{},
> +};
> +
> +static struct platform_driver ti_dma_xbar_driver = {
> +	.driver = {
> +		.name = "ti-dma-crossbar",
> +		.of_match_table = of_match_ptr(ti_dma_xbar_match),
> +	},
> +	.probe	= ti_dma_xbar_probe,
> +};
> +
> +int omap_dmaxbar_init(void)
> +{
> +	return platform_driver_register(&ti_dma_xbar_driver);
> +}
> +arch_initcall(omap_dmaxbar_init);

Thanks,
Maxime

-- 
Maxime Ripard, Free Electrons
Embedded Linux, Kernel and Android engineering
http://free-electrons.com

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