dmaengine: Add dma router for pl08x in LPC32XX SoC

LPC32XX connects few of its peripherals to pl08x DMA thru a multiplexer,
this driver allows to route a signal request line thru the multiplexer for
given peripheral.

Signed-off-by: Piotr Wojtaszczyk <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Vinod Koul <[e-mail]>

MAINTAINERS

···
 F:	Documentation/devicetree/bindings/i2c/nxp,pnx-i2c.yaml
 F:	arch/arm/boot/dts/nxp/lpc/lpc32*
 F:	arch/arm/mach-lpc32xx/
+F:	drivers/dma/lpc32xx-dmamux.c
 F:	drivers/i2c/busses/i2c-pnx.c
 F:	drivers/net/ethernet/nxp/lpc_eth.c
 F:	drivers/usb/host/ohci-nxp.c

arch/arm/mach-lpc32xx/Kconfig

···
 	select CLKSRC_LPC32XX
 	select CPU_ARM926T
 	select GPIOLIB
+	select LPC32XX_DMAMUX if AMBA_PL08X
 	help
 	  Support for the NXP LPC32XX family of processors

drivers/dma/Kconfig

···
 	  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

drivers/dma/Makefile

···
 obj-$(CONFIG_K3_DMA) += k3dma.o
 obj-$(CONFIG_LOONGSON1_APB_DMA) += loongson1-apb-dma.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

drivers/dma/lpc32xx-dmamux.c

···
+// SPDX-License-Identifier: GPL-2.0-only
+//
+// Copyright 2024 Timesys Corporation <[e-mail]>
+//
+// Based on TI DMA Crossbar driver by:
+//   Copyright (C) 2015 Texas Instruments Incorporated - http://www.ti.com
+//   Author: Peter Ujfalusi <[e-mail]>
+
+#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;
+
+	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;
+		}
+	}
+	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);
+	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;
+
+	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);