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@xxxxxxxxxxx>
> ---
> 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@xxxxxxxxx>
> L: linux-arm-kernel@xxxxxxxxxxxxxxxxxxx (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@xxxxxxx>
> 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@xxxxxxxxxxx>
> +//
> +// Based on TI DMA Crossbar driver by:
> +// Copyright (C) 2015 Texas Instruments Incorporated - http://www.ti.com
> +// Author: Peter Ujfalusi <peter.ujfalusi@xxxxxx>
> +
> +#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
>
