Message-ID: <20170406064046.GF4094@localhost>
Date:   Thu, 6 Apr 2017 12:10:46 +0530
From:   Vinod Koul <vinod.koul@...el.com>
To:     M'boumba Cedric Madianga <cedric.madianga@...il.com>
Cc:     robh+dt@...nel.org, mark.rutland@....com,
        mcoquelin.stm32@...il.com, alexandre.torgue@...com,
        dan.j.williams@...el.com, dmaengine@...r.kernel.org,
        devicetree@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH 2/5] dmaengine: Add STM32 DMAMUX driver

On Mon, Mar 13, 2017 at 03:15:58PM +0100, M'boumba Cedric Madianga wrote:
> This patch implements the STM32 DMAMUX driver

Can you describe the controller here pls

> 
> Signed-off-by: M'boumba Cedric Madianga <cedric.madianga@...il.com>
> ---
>  drivers/dma/Kconfig        |   9 ++
>  drivers/dma/Makefile       |   1 +
>  drivers/dma/stm32-dmamux.c | 231 +++++++++++++++++++++++++++++++++++++++++++++
>  3 files changed, 241 insertions(+)
>  create mode 100644 drivers/dma/stm32-dmamux.c
> 
> diff --git a/drivers/dma/Kconfig b/drivers/dma/Kconfig
> index fc3435c..6ab80c9 100644
> --- a/drivers/dma/Kconfig
> +++ b/drivers/dma/Kconfig
> @@ -461,6 +461,15 @@ config STM32_DMA
>  	  If you have a board based on such a MCU and wish to use DMA say Y
>  	  here.
>  
> +config STM32_DMAMUX
> +	bool "STMicroelectronics STM32 dma multiplexer support"
> +	depends on STM32_DMA

can you add compile test here so that we can get better compile coverage

> +	help
> +	  Enable support for the on-chip DMA multiplexer on STMicroelectronics
> +	  STM32 MCUs.
> +	  If you have a board based on such a MCU and wish to use DMAMUX say Y
> +	  here.
> +
>  config S3C24XX_DMAC
>  	bool "Samsung S3C24XX DMA support"
>  	depends on ARCH_S3C24XX || COMPILE_TEST
> diff --git a/drivers/dma/Makefile b/drivers/dma/Makefile
> index 0b723e9..449c7a3 100644
> --- a/drivers/dma/Makefile
> +++ b/drivers/dma/Makefile
> @@ -57,6 +57,7 @@ obj-$(CONFIG_RENESAS_DMA) += sh/
>  obj-$(CONFIG_SIRF_DMA) += sirf-dma.o
>  obj-$(CONFIG_STE_DMA40) += ste_dma40.o ste_dma40_ll.o
>  obj-$(CONFIG_STM32_DMA) += stm32-dma.o
> +obj-$(CONFIG_STM32_DMAMUX) += stm32-dmamux.o
>  obj-$(CONFIG_S3C24XX_DMAC) += s3c24xx-dma.o
>  obj-$(CONFIG_TXX9_DMAC) += txx9dmac.o
>  obj-$(CONFIG_TEGRA20_APB_DMA) += tegra20-apb-dma.o
> diff --git a/drivers/dma/stm32-dmamux.c b/drivers/dma/stm32-dmamux.c
> new file mode 100644
> index 0000000..3003546
> --- /dev/null
> +++ b/drivers/dma/stm32-dmamux.c
> @@ -0,0 +1,231 @@
> +/*
> + * DMA Router driver for STM32 DMA MUX
> + *
> + * Copyright (C) 2015 M'Boumba Cedric Madianga <cedric.madianga@...il.com>

we are in '17 now :)

> + *
> + * Based on LPC18xx/43xx DMA MUX and TI DMA XBAR
> + *
> + * 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/clk.h>
> +#include <linux/delay.h>
> +#include <linux/err.h>
> +#include <linux/init.h>
> +#include <linux/of_device.h>
> +#include <linux/of_dma.h>
> +#include <linux/reset.h>
> +#include <linux/slab.h>
> +
> +#define STM32_DMAMUX_CCR(x)		(0x4 * (x))
> +#define STM32_DMAMUX_MAX_CHANNELS	32
> +#define STM32_DMAMUX_MAX_REQUESTS	255
> +
> +struct stm32_dmamux {
> +	u32 chan_id;
> +	u32 request;
> +	bool busy;
> +};
> +
> +struct stm32_dmamux_data {
> +	struct dma_router dmarouter;
> +	struct stm32_dmamux *muxes;
> +	struct clk *clk;
> +	void __iomem *iomem;
> +	u32 dmamux_requests; /* number of DMA requests connected to DMAMUX */
> +	u32 dmamux_channels; /* Number of DMA channels supported */
> +};
> +
> +static inline u32 stm32_dmamux_read(void __iomem *iomem, u32 reg)
> +{
> +	return readl_relaxed(iomem + reg);
> +}
> +
> +static inline void stm32_dmamux_write(void __iomem *iomem, u32 reg, u32 val)
> +{
> +	writel_relaxed(val, iomem + reg);
> +}
> +
> +static void stm32_dmamux_free(struct device *dev, void *route_data)
> +{
> +	struct stm32_dmamux_data *dmamux = dev_get_drvdata(dev);
> +	struct stm32_dmamux *mux = route_data;
> +
> +	/* Clear dma request for the right channel */
> +	stm32_dmamux_write(dmamux->iomem, STM32_DMAMUX_CCR(mux->chan_id), 0);
> +	clk_disable(dmamux->clk);
> +	mux->busy = false;
> +
> +	dev_dbg(dev, "Unmapping dma-router%dchan%d (was routed to request%d)\n",
> +		dev->id, mux->chan_id, mux->request);
> +}
> +
> +static void *stm32_dmamux_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 stm32_dmamux_data *dmamux = platform_get_drvdata(pdev);
> +	struct stm32_dmamux *mux;
> +	u32 chan_id;
> +	int ret;
> +
> +	if (dma_spec->args_count != 4) {
> +		dev_err(&pdev->dev, "invalid number of dma mux args\n");
> +		return ERR_PTR(-EINVAL);
> +	}
> +
> +	if (dma_spec->args[0] >= dmamux->dmamux_channels) {
> +		dev_err(&pdev->dev, "invalid channel id: %d\n",
> +			dma_spec->args[0]);
> +		return ERR_PTR(-EINVAL);
> +	}
> +
> +	if (dma_spec->args[1] > dmamux->dmamux_requests) {
> +		dev_err(&pdev->dev, "invalid mux request number: %d\n",
> +			dma_spec->args[1]);
> +		return ERR_PTR(-EINVAL);
> +	}
> +
> +	/* The of_node_put() will be done in of_dma_router_xlate function */
> +	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 ERR_PTR(-EINVAL);
> +	}
> +
> +	chan_id = dma_spec->args[0];
> +	mux = &dmamux->muxes[chan_id];
> +	mux->chan_id = chan_id;
> +	mux->request = dma_spec->args[1];
> +
> +	if (mux->busy) {
> +		dev_err(&pdev->dev, "dma channel %d busy with request %d\n",
> +			chan_id, mux->request);
> +		return ERR_PTR(-EBUSY);
> +	}
> +
> +	ret = clk_enable(dmamux->clk);
> +	if (ret < 0) {
> +		dev_err(&pdev->dev, "clk_enable failed: %d\n", ret);
> +		return ERR_PTR(ret);
> +	}
> +
> +	stm32_dmamux_write(dmamux->iomem, STM32_DMAMUX_CCR(mux->chan_id),
> +			   mux->request);
> +	mux->busy = true;
> +
> +	dev_dbg(&pdev->dev, "Mapping dma-router%dchan%d to request%d\n",
> +		pdev->dev.id, mux->chan_id, mux->request);
> +
> +	return mux;
> +}
> +
> +static int stm32_dmamux_probe(struct platform_device *pdev)
> +{
> +	struct device_node *dma_node, *node = pdev->dev.of_node;
> +	struct stm32_dmamux_data *dmamux;
> +	struct reset_control *rst;
> +	struct resource *res;
> +	int ret;
> +
> +	if (!node)
> +		return -ENODEV;
> +
> +	dmamux = devm_kzalloc(&pdev->dev, sizeof(struct stm32_dmamux_data),
> +			      GFP_KERNEL);
> +	if (!dmamux)
> +		return -ENOMEM;
> +
> +	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;
> +	}
> +	of_node_put(dma_node);
> +
> +	ret = of_property_read_u32(node, "dma-channels",
> +				   &dmamux->dmamux_channels);

can we have property_xxx calls alone, that way driver is not strictly
dependent on of

> +	if (ret)
> +		dmamux->dmamux_channels = STM32_DMAMUX_MAX_CHANNELS;
> +
> +	ret = of_property_read_u32(node, "dma-requests",
> +				   &dmamux->dmamux_requests);
> +	if (ret)
> +		dmamux->dmamux_requests = STM32_DMAMUX_MAX_REQUESTS;
> +
> +	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
> +	if (!res)
> +		return -ENODEV;
> +
> +	dmamux->iomem = devm_ioremap_resource(&pdev->dev, res);
> +	if (!dmamux->iomem)
> +		return -ENOMEM;
> +
> +	dmamux->clk = devm_clk_get(&pdev->dev, NULL);
> +	if (IS_ERR(dmamux->clk)) {
> +		dev_err(&pdev->dev, "Missing controller clock\n");
> +		return PTR_ERR(dmamux->clk);
> +	}
> +	ret = clk_prepare(dmamux->clk);
> +	if (ret < 0) {
> +		dev_err(&pdev->dev, "clk_prep failed: %d\n", ret);
> +		return ret;
> +	}
> +
> +	dmamux->muxes = devm_kcalloc(&pdev->dev, dmamux->dmamux_channels,
> +				     sizeof(struct stm32_dmamux),
> +				     GFP_KERNEL);
> +	if (!dmamux->muxes)
> +		return -ENOMEM;
> +
> +	rst = devm_reset_control_get(&pdev->dev, NULL);
> +	if (!IS_ERR(rst)) {
> +		ret = clk_enable(dmamux->clk);
> +		if (ret < 0) {
> +			dev_err(&pdev->dev, "clk_enable failed: %d\n", ret);
> +			return ret;
> +		}
> +		reset_control_assert(rst);
> +		udelay(2);
> +		reset_control_deassert(rst);
> +		clk_disable(dmamux->clk);
> +	}
> +
> +	dmamux->dmarouter.dev = &pdev->dev;
> +	dmamux->dmarouter.route_free = stm32_dmamux_free;
> +	platform_set_drvdata(pdev, dmamux);
> +
> +	ret = of_dma_router_register(node, stm32_dmamux_route_allocate,
> +				     &dmamux->dmarouter);
> +	if (ret < 0) {
> +		dev_err(&pdev->dev,
> +			"STM32 DMAMUX DMA OF registration failed %d\n", ret);
> +		return ret;
> +	}
> +
> +	dev_info(&pdev->dev, "STM32 DMAMUX driver registered\n");
> +
> +	return 0;
> +}
> +
> +static const struct of_device_id stm32_dmamux_match[] = {
> +	{ .compatible = "st,stm32-dmamux" },
> +	{},
> +};
> +
> +static struct platform_driver stm32_dmamux_driver = {
> +	.probe	= stm32_dmamux_probe,
> +	.driver = {
> +		.name = "stm32-dmamux",
> +		.of_match_table = stm32_dmamux_match,
> +	},
> +};
> +
> +static int __init stm32_dmamux_init(void)
> +{
> +	return platform_driver_register(&stm32_dmamux_driver);
> +}
> +arch_initcall(stm32_dmamux_init);

why not module init, wouldnt defer probe solve the dependencies

-- 
~Vinod

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