Message-ID: <ZoMHxC7cRN45s0yl@lizhi-Precision-Tower-5810>
Date: Mon, 1 Jul 2024 15:47:16 -0400
From: Frank Li <Frank.li@....com>
To: Piotr Wojtaszczyk <piotr.wojtaszczyk@...esys.com>
Cc: Vinod Koul <vkoul@...nel.org>, Rob Herring <robh@...nel.org>,
	Krzysztof Kozlowski <krzk+dt@...nel.org>,
	Conor Dooley <conor+dt@...nel.org>,
	"J.M.B. Downing" <jonathan.downing@...tel.com>,
	Vladimir Zapolskiy <vz@...ia.com>,
	Liam Girdwood <lgirdwood@...il.com>,
	Mark Brown <broonie@...nel.org>,
	Russell King <linux@...linux.org.uk>,
	Michael Turquette <mturquette@...libre.com>,
	Stephen Boyd <sboyd@...nel.org>, Andi Shyti <andi.shyti@...nel.org>,
	Miquel Raynal <miquel.raynal@...tlin.com>,
	Richard Weinberger <richard@....at>,
	Vignesh Raghavendra <vigneshr@...com>,
	Jaroslav Kysela <perex@...ex.cz>, Takashi Iwai <tiwai@...e.com>,
	Arnd Bergmann <arnd@...db.de>, Yangtao Li <frank.li@...o.com>,
	Li Zetao <lizetao1@...wei.com>, Chancel Liu <chancel.liu@....com>,
	Michael Ellerman <mpe@...erman.id.au>,
	Corentin Labbe <clabbe@...libre.com>, dmaengine@...r.kernel.org,
	devicetree@...r.kernel.org, linux-kernel@...r.kernel.org,
	linux-arm-kernel@...ts.infradead.org, alsa-devel@...a-project.org,
	linuxppc-dev@...ts.ozlabs.org, linux-sound@...r.kernel.org,
	linux-clk@...r.kernel.org, linux-i2c@...r.kernel.org,
	linux-mtd@...ts.infradead.org
Subject: Re: [Patch v5 08/12] dmaengine: Add dma router for pl08x in LPC32XX
 SoC

On Thu, Jun 27, 2024 at 05:00:26PM +0200, Piotr Wojtaszczyk wrote:
> LPC32XX connects few of its peripherals to pl08x DMA thru a multiplexer,
                                                       ^^^ through?
I google 'thru', most said it is informal spell of 'through'.

> this driver allows to route a signal request line thru the multiplexer for
> given peripheral.
> 
> Signed-off-by: Piotr Wojtaszczyk <piotr.wojtaszczyk@...esys.com>
> ---
> Changes for v5:
> - Fix struct declaration order
> - Removed unused variables
> - Break search loop if expected lpc32xx_muxes[i].signal is found
> 
> Changes for v4:
> - This patch is new in v4
> 
>  MAINTAINERS                  |   1 +
>  drivers/dma/Kconfig          |   9 ++
>  drivers/dma/Makefile         |   1 +
>  drivers/dma/lpc32xx-dmamux.c | 195 +++++++++++++++++++++++++++++++++++
>  4 files changed, 206 insertions(+)
>  create mode 100644 drivers/dma/lpc32xx-dmamux.c
> 
> diff --git a/MAINTAINERS b/MAINTAINERS
> index ceec359c68fc..118d48747641 100644
> --- a/MAINTAINERS
> +++ b/MAINTAINERS
> @@ -2404,6 +2404,7 @@ R:	Vladimir Zapolskiy <vz@...ia.com>
>  L:	linux-arm-kernel@...ts.infradead.org (moderated for non-subscribers)
>  S:	Maintained
>  F:	Documentation/devicetree/bindings/dma/nxp,lpc3220-dmamux.yaml
> +F:	drivers/dma/lpc32xx-dmamux.c
>  
>  ARM/Marvell Dove/MV78xx0/Orion SOC support
>  M:	Andrew Lunn <andrew@...n.ch>
> diff --git a/drivers/dma/Kconfig b/drivers/dma/Kconfig
> index 002a5ec80620..aeace3d7e066 100644
> --- a/drivers/dma/Kconfig
> +++ b/drivers/dma/Kconfig
> @@ -378,6 +378,15 @@ config LPC18XX_DMAMUX
>  	  Enable support for DMA on NXP LPC18xx/43xx platforms
>  	  with PL080 and multiplexed DMA request lines.
>  
> +config LPC32XX_DMAMUX
> +	bool "NXP LPC32xx DMA MUX for PL080"
> +	depends on ARCH_LPC32XX || COMPILE_TEST
> +	depends on OF && AMBA_PL08X
> +	select MFD_SYSCON
> +	help
> +	  Support for PL080 multiplexed DMA request lines on
> +	  LPC32XX platrofm.
> +
>  config LS2X_APB_DMA
>  	tristate "Loongson LS2X APB DMA support"
>  	depends on LOONGARCH || COMPILE_TEST
> diff --git a/drivers/dma/Makefile b/drivers/dma/Makefile
> index 802ca916f05f..6f1350b62e7f 100644
> --- a/drivers/dma/Makefile
> +++ b/drivers/dma/Makefile
> @@ -50,6 +50,7 @@ obj-$(CONFIG_INTEL_IOATDMA) += ioat/
>  obj-y += idxd/
>  obj-$(CONFIG_K3_DMA) += k3dma.o
>  obj-$(CONFIG_LPC18XX_DMAMUX) += lpc18xx-dmamux.o
> +obj-$(CONFIG_LPC32XX_DMAMUX) += lpc32xx-dmamux.o
>  obj-$(CONFIG_LS2X_APB_DMA) += ls2x-apb-dma.o
>  obj-$(CONFIG_MILBEAUT_HDMAC) += milbeaut-hdmac.o
>  obj-$(CONFIG_MILBEAUT_XDMAC) += milbeaut-xdmac.o
> diff --git a/drivers/dma/lpc32xx-dmamux.c b/drivers/dma/lpc32xx-dmamux.c
> new file mode 100644
> index 000000000000..351d7e23e615
> --- /dev/null
> +++ b/drivers/dma/lpc32xx-dmamux.c
> @@ -0,0 +1,195 @@
> +// SPDX-License-Identifier: GPL-2.0-only
> +//
> +// Copyright 2024 Timesys Corporation <piotr.wojtaszczyk@...esys.com>
> +//
> +// Based on TI DMA Crossbar driver by:
> +//   Copyright (C) 2015 Texas Instruments Incorporated - http://www.ti.com
> +//   Author: Peter Ujfalusi <peter.ujfalusi@...com>
> +
> +#include <linux/err.h>
> +#include <linux/init.h>
> +#include <linux/mfd/syscon.h>
> +#include <linux/of.h>
> +#include <linux/of_dma.h>
> +#include <linux/of_platform.h>
> +#include <linux/platform_device.h>
> +#include <linux/regmap.h>
> +#include <linux/spinlock.h>
> +
> +#define LPC32XX_SSP_CLK_CTRL 0x78
> +#define LPC32XX_I2S_CLK_CTRL 0x7c
> +
> +struct lpc32xx_dmamux {
> +	int signal;
> +	char *name_sel0;
> +	char *name_sel1;
> +	int muxval;
> +	int muxreg;
> +	int bit;
> +	bool busy;
> +};
> +
> +struct lpc32xx_dmamux_data {
> +	struct dma_router dmarouter;
> +	struct regmap *reg;
> +	spinlock_t lock; /* protects busy status flag */
> +};
> +
> +/* From LPC32x0 User manual "3.2.1 DMA request signals" */
> +static struct lpc32xx_dmamux lpc32xx_muxes[] = {
> +	{
> +		.signal = 3,
> +		.name_sel0 = "spi2-rx-tx",
> +		.name_sel1 = "ssp1-rx",
> +		.muxreg = LPC32XX_SSP_CLK_CTRL,
> +		.bit = 5,
> +	},
> +	{
> +		.signal = 10,
> +		.name_sel0 = "uart7-rx",
> +		.name_sel1 = "i2s1-dma1",
> +		.muxreg = LPC32XX_I2S_CLK_CTRL,
> +		.bit = 4,
> +	},
> +	{
> +		.signal = 11,
> +		.name_sel0 = "spi1-rx-tx",
> +		.name_sel1 = "ssp1-tx",
> +		.muxreg = LPC32XX_SSP_CLK_CTRL,
> +		.bit = 4,
> +	},
> +	{
> +		.signal = 14,
> +		.name_sel0 = "none",
> +		.name_sel1 = "ssp0-rx",
> +		.muxreg = LPC32XX_SSP_CLK_CTRL,
> +		.bit = 3,
> +	},
> +	{
> +		.signal = 15,
> +		.name_sel0 = "none",
> +		.name_sel1 = "ssp0-tx",
> +		.muxreg = LPC32XX_SSP_CLK_CTRL,
> +		.bit = 2,
> +	},
> +};
> +
> +static void lpc32xx_dmamux_release(struct device *dev, void *route_data)
> +{
> +	struct lpc32xx_dmamux_data *dmamux = dev_get_drvdata(dev);
> +	struct lpc32xx_dmamux *mux = route_data;
> +
> +	dev_dbg(dev, "releasing dma request signal %d routed to %s\n",
> +		mux->signal, mux->muxval ? mux->name_sel1 : mux->name_sel1);
> +
> +	guard(spinlock)(&dmamux->lock);
> +
> +	mux->busy = false;
> +}
> +
> +static void *lpc32xx_dmamux_reserve(struct of_phandle_args *dma_spec,
> +				    struct of_dma *ofdma)
> +{
> +	struct platform_device *pdev = of_find_device_by_node(ofdma->of_node);
> +	struct device *dev = &pdev->dev;
> +	struct lpc32xx_dmamux_data *dmamux = platform_get_drvdata(pdev);
> +	unsigned long flags;
> +	struct lpc32xx_dmamux *mux = NULL;
> +	int i;

It'd better keep reverse christmas tree order.

> +
> +	if (dma_spec->args_count != 3) {
> +		dev_err(&pdev->dev, "invalid number of dma mux args\n");
> +		return ERR_PTR(-EINVAL);
> +	}
> +
> +	for (i = 0; i < ARRAY_SIZE(lpc32xx_muxes); i++) {
> +		if (lpc32xx_muxes[i].signal == dma_spec->args[0]) {
> +			mux = &lpc32xx_muxes[i];
> +			break;
> +		}
> +	}

Add empty line here.

> +	if (!mux) {
> +		dev_err(&pdev->dev, "invalid mux request number: %d\n",
> +			dma_spec->args[0]);
> +		return ERR_PTR(-EINVAL);
> +	}
> +
> +	if (dma_spec->args[2] > 1) {
> +		dev_err(&pdev->dev, "invalid dma mux value: %d\n",
> +			dma_spec->args[1]);
> +		return ERR_PTR(-EINVAL);
> +	}
> +
> +	/* The of_node_put() will be done in the core for the node */
> +	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);
> +	}
> +
> +	spin_lock_irqsave(&dmamux->lock, flags);

you already use guard in lpc32xx_dmamux_release().
here is better place to use guard also.

because it spin lock, better use scoped_guard() {}.

> +	if (mux->busy) {
> +		spin_unlock_irqrestore(&dmamux->lock, flags);
> +		dev_err(dev, "dma request signal %d busy, routed to %s\n",
> +			mux->signal, mux->muxval ? mux->name_sel1 : mux->name_sel1);
> +		of_node_put(dma_spec->np);
> +		return ERR_PTR(-EBUSY);
> +	}
> +
> +	mux->busy = true;
> +	mux->muxval = dma_spec->args[2] ? BIT(mux->bit) : 0;
> +
> +	regmap_update_bits(dmamux->reg, mux->muxreg, BIT(mux->bit), mux->muxval);
> +	spin_unlock_irqrestore(&dmamux->lock, flags);
> +
> +	dma_spec->args[2] = 0;
> +	dma_spec->args_count = 2;

Why need update dma_spec here? Suppose it just pass down dt information. 

> +
> +	dev_dbg(dev, "dma request signal %d routed to %s\n",
> +		mux->signal, mux->muxval ? mux->name_sel1 : mux->name_sel1);
> +
> +	return mux;
> +}
> +
> +static int lpc32xx_dmamux_probe(struct platform_device *pdev)
> +{
> +	struct device_node *np = pdev->dev.of_node;
> +	struct lpc32xx_dmamux_data *dmamux;
> +
> +	dmamux = devm_kzalloc(&pdev->dev, sizeof(*dmamux), GFP_KERNEL);
> +	if (!dmamux)
> +		return -ENOMEM;
> +
> +	dmamux->reg = syscon_node_to_regmap(np->parent);
> +	if (IS_ERR(dmamux->reg)) {
> +		dev_err(&pdev->dev, "syscon lookup failed\n");
> +		return PTR_ERR(dmamux->reg);
> +	}
> +
> +	spin_lock_init(&dmamux->lock);
> +	platform_set_drvdata(pdev, dmamux);
> +	dmamux->dmarouter.dev = &pdev->dev;
> +	dmamux->dmarouter.route_free = lpc32xx_dmamux_release;
> +
> +	return of_dma_router_register(np, lpc32xx_dmamux_reserve,
> +				      &dmamux->dmarouter);
> +}
> +
> +static const struct of_device_id lpc32xx_dmamux_match[] = {
> +	{ .compatible = "nxp,lpc3220-dmamux" },
> +	{},
> +};
> +
> +static struct platform_driver lpc32xx_dmamux_driver = {
> +	.probe	= lpc32xx_dmamux_probe,
> +	.driver = {
> +		.name = "lpc32xx-dmamux",
> +		.of_match_table = lpc32xx_dmamux_match,
> +	},
> +};
> +
> +static int __init lpc32xx_dmamux_init(void)
> +{
> +	return platform_driver_register(&lpc32xx_dmamux_driver);
> +}
> +arch_initcall(lpc32xx_dmamux_init);
> -- 
> 2.25.1
> 

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