dmaengine: add driver for Sophgo CV18XX/SG200X dmamux

Sophgo CV18XX/SG200X use DW AXI CORE with a multiplexer for remapping
its request lines. The multiplexer supports at most 8 request lines.

Add driver for Sophgo CV18XX/SG200X DMA multiplexer.

Signed-off-by: Inochi Amaoto <[e-mail]>
Tested-by: Alexander Sverdlin <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Vinod Koul <[e-mail]>

drivers/dma/Kconfig

···
 	  These are exposed via extra functions on the switch's
 	  upstream port. Each function exposes one DMA channel.
 
+config SOPHGO_CV1800B_DMAMUX
+	tristate "Sophgo CV1800/SG2000 series SoC DMA multiplexer support"
+	depends on MFD_SYSCON
+	depends on ARCH_SOPHGO || COMPILE_TEST
+	help
+	  Support for the DMA multiplexer on Sophgo CV1800/SG2000
+	  series SoCs.
+	  Say Y here if your board have this soc.
+
 config STE_DMA40
 	bool "ST-Ericsson DMA40 support"
 	depends on ARCH_U8500

drivers/dma/Makefile

···
 obj-$(CONFIG_PXA_DMA) += pxa_dma.o
 obj-$(CONFIG_RENESAS_DMA) += sh/
 obj-$(CONFIG_SF_PDMA) += sf-pdma/
+obj-$(CONFIG_SOPHGO_CV1800B_DMAMUX) += cv1800b-dmamux.o
 obj-$(CONFIG_STE_DMA40) += ste_dma40.o ste_dma40_ll.o
 obj-$(CONFIG_SPRD_DMA) += sprd-dma.o
 obj-$(CONFIG_TXX9_DMAC) += txx9dmac.o

drivers/dma/cv1800b-dmamux.c

···
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (C) 2025 Inochi Amaoto <[e-mail]>
+ */
+
+#include <linux/bitops.h>
+#include <linux/cleanup.h>
+#include <linux/module.h>
+#include <linux/of_dma.h>
+#include <linux/of_address.h>
+#include <linux/of_platform.h>
+#include <linux/platform_device.h>
+#include <linux/llist.h>
+#include <linux/regmap.h>
+#include <linux/spinlock.h>
+#include <linux/mfd/syscon.h>
+
+#define REG_DMA_CHANNEL_REMAP0		0x154
+#define REG_DMA_CHANNEL_REMAP1		0x158
+#define REG_DMA_INT_MUX			0x298
+
+#define DMAMUX_NCELLS			2
+#define MAX_DMA_MAPPING_ID		42
+#define MAX_DMA_CPU_ID			2
+#define MAX_DMA_CH_ID			7
+
+#define DMAMUX_INTMUX_REGISTER_LEN	4
+#define DMAMUX_NR_CH_PER_REGISTER	4
+#define DMAMUX_BIT_PER_CH		8
+#define DMAMUX_CH_MASk			GENMASK(5, 0)
+#define DMAMUX_INT_BIT_PER_CPU		10
+#define DMAMUX_CH_UPDATE_BIT		BIT(31)
+
+#define DMAMUX_CH_REGPOS(chid) \
+	((chid) / DMAMUX_NR_CH_PER_REGISTER)
+#define DMAMUX_CH_REGOFF(chid) \
+	((chid) % DMAMUX_NR_CH_PER_REGISTER)
+#define DMAMUX_CH_REG(chid) \
+	((DMAMUX_CH_REGPOS(chid) * sizeof(u32)) + \
+	 REG_DMA_CHANNEL_REMAP0)
+#define DMAMUX_CH_SET(chid, val) \
+	(((val) << (DMAMUX_CH_REGOFF(chid) * DMAMUX_BIT_PER_CH)) | \
+	 DMAMUX_CH_UPDATE_BIT)
+#define DMAMUX_CH_MASK(chid) \
+	DMAMUX_CH_SET(chid, DMAMUX_CH_MASk)
+
+#define DMAMUX_INT_BIT(chid, cpuid) \
+	BIT((cpuid) * DMAMUX_INT_BIT_PER_CPU + (chid))
+#define DMAMUX_INTEN_BIT(cpuid) \
+	DMAMUX_INT_BIT(8, cpuid)
+#define DMAMUX_INT_CH_BIT(chid, cpuid) \
+	(DMAMUX_INT_BIT(chid, cpuid) | DMAMUX_INTEN_BIT(cpuid))
+#define DMAMUX_INT_MASK(chid) \
+	(DMAMUX_INT_BIT(chid, 0) | \
+	 DMAMUX_INT_BIT(chid, 1) | \
+	 DMAMUX_INT_BIT(chid, 2))
+#define DMAMUX_INT_CH_MASK(chid, cpuid) \
+	(DMAMUX_INT_MASK(chid) | DMAMUX_INTEN_BIT(cpuid))
+
+struct cv1800_dmamux_data {
+	struct dma_router	dmarouter;
+	struct regmap		*regmap;
+	spinlock_t		lock;
+	struct llist_head	free_maps;
+	struct llist_head	reserve_maps;
+	DECLARE_BITMAP(mapped_peripherals, MAX_DMA_MAPPING_ID);
+};
+
+struct cv1800_dmamux_map {
+	struct llist_node node;
+	unsigned int channel;
+	unsigned int peripheral;
+	unsigned int cpu;
+};
+
+static void cv1800_dmamux_free(struct device *dev, void *route_data)
+{
+	struct cv1800_dmamux_data *dmamux = dev_get_drvdata(dev);
+	struct cv1800_dmamux_map *map = route_data;
+
+	guard(spinlock_irqsave)(&dmamux->lock);
+
+	regmap_update_bits(dmamux->regmap,
+			   DMAMUX_CH_REG(map->channel),
+			   DMAMUX_CH_MASK(map->channel),
+			   DMAMUX_CH_UPDATE_BIT);
+
+	regmap_update_bits(dmamux->regmap, REG_DMA_INT_MUX,
+			   DMAMUX_INT_CH_MASK(map->channel, map->cpu),
+			   DMAMUX_INTEN_BIT(map->cpu));
+
+	dev_dbg(dev, "free channel %u for req %u (cpu %u)\n",
+		map->channel, map->peripheral, map->cpu);
+}
+
+static void *cv1800_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 cv1800_dmamux_data *dmamux = platform_get_drvdata(pdev);
+	struct cv1800_dmamux_map *map;
+	struct llist_node *node;
+	unsigned long flags;
+	unsigned int chid, devid, cpuid;
+	int ret;
+
+	if (dma_spec->args_count != DMAMUX_NCELLS) {
+		dev_err(&pdev->dev, "invalid number of dma mux args\n");
+		return ERR_PTR(-EINVAL);
+	}
+
+	devid = dma_spec->args[0];
+	cpuid = dma_spec->args[1];
+	dma_spec->args_count = 1;
+
+	if (devid > MAX_DMA_MAPPING_ID) {
+		dev_err(&pdev->dev, "invalid device id: %u\n", devid);
+		return ERR_PTR(-EINVAL);
+	}
+
+	if (cpuid > MAX_DMA_CPU_ID) {
+		dev_err(&pdev->dev, "invalid cpu id: %u\n", cpuid);
+		return ERR_PTR(-EINVAL);
+	}
+
+	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 (test_bit(devid, dmamux->mapped_peripherals)) {
+		llist_for_each_entry(map, dmamux->reserve_maps.first, node) {
+			if (map->peripheral == devid && map->cpu == cpuid)
+				goto found;
+		}
+
+		ret = -EINVAL;
+		goto failed;
+	} else {
+		node = llist_del_first(&dmamux->free_maps);
+		if (!node) {
+			ret = -ENODEV;
+			goto failed;
+		}
+
+		map = llist_entry(node, struct cv1800_dmamux_map, node);
+		llist_add(&map->node, &dmamux->reserve_maps);
+		set_bit(devid, dmamux->mapped_peripherals);
+	}
+
+found:
+	chid = map->channel;
+	map->peripheral = devid;
+	map->cpu = cpuid;
+
+	regmap_set_bits(dmamux->regmap,
+			DMAMUX_CH_REG(chid),
+			DMAMUX_CH_SET(chid, devid));
+
+	regmap_update_bits(dmamux->regmap, REG_DMA_INT_MUX,
+			   DMAMUX_INT_CH_MASK(chid, cpuid),
+			   DMAMUX_INT_CH_BIT(chid, cpuid));
+
+	spin_unlock_irqrestore(&dmamux->lock, flags);
+
+	dma_spec->args[0] = chid;
+
+	dev_dbg(&pdev->dev, "register channel %u for req %u (cpu %u)\n",
+		chid, devid, cpuid);
+
+	return map;
+
+failed:
+	spin_unlock_irqrestore(&dmamux->lock, flags);
+	of_node_put(dma_spec->np);
+	dev_err(&pdev->dev, "errno %d\n", ret);
+	return ERR_PTR(ret);
+}
+
+static int cv1800_dmamux_probe(struct platform_device *pdev)
+{
+	struct device *dev = &pdev->dev;
+	struct device_node *mux_node = dev->of_node;
+	struct cv1800_dmamux_data *data;
+	struct cv1800_dmamux_map *tmp;
+	struct device *parent = dev->parent;
+	struct regmap *regmap = NULL;
+	unsigned int i;
+
+	if (!parent)
+		return -ENODEV;
+
+	regmap = device_node_to_regmap(parent->of_node);
+	if (IS_ERR(regmap))
+		return PTR_ERR(regmap);
+
+	data = devm_kzalloc(dev, sizeof(*data), GFP_KERNEL);
+	if (!data)
+		return -ENOMEM;
+
+	spin_lock_init(&data->lock);
+	init_llist_head(&data->free_maps);
+	init_llist_head(&data->reserve_maps);
+
+	for (i = 0; i <= MAX_DMA_CH_ID; i++) {
+		tmp = devm_kmalloc(dev, sizeof(*tmp), GFP_KERNEL);
+		if (!tmp) {
+			/* It is OK for not allocating all channel */
+			dev_warn(dev, "can not allocate channel %u\n", i);
+			continue;
+		}
+
+		init_llist_node(&tmp->node);
+		tmp->channel = i;
+		llist_add(&tmp->node, &data->free_maps);
+	}
+
+	/* if no channel is allocated, the probe must fail */
+	if (llist_empty(&data->free_maps))
+		return -ENOMEM;
+
+	data->regmap = regmap;
+	data->dmarouter.dev = dev;
+	data->dmarouter.route_free = cv1800_dmamux_free;
+
+	platform_set_drvdata(pdev, data);
+
+	return of_dma_router_register(mux_node,
+				      cv1800_dmamux_route_allocate,
+				      &data->dmarouter);
+}
+
+static void cv1800_dmamux_remove(struct platform_device *pdev)
+{
+	of_dma_controller_free(pdev->dev.of_node);
+}
+
+static const struct of_device_id cv1800_dmamux_ids[] = {
+	{ .compatible = "sophgo,cv1800b-dmamux", },
+	{ }
+};
+MODULE_DEVICE_TABLE(of, cv1800_dmamux_ids);
+
+static struct platform_driver cv1800_dmamux_driver = {
+	.probe = cv1800_dmamux_probe,
+	.remove = cv1800_dmamux_remove,
+	.driver = {
+		.name = "cv1800-dmamux",
+		.of_match_table = cv1800_dmamux_ids,
+	},
+};
+module_platform_driver(cv1800_dmamux_driver);
+
+MODULE_AUTHOR("Inochi Amaoto <[e-mail]>");
+MODULE_DESCRIPTION("Sophgo CV1800/SG2000 Series SoC DMAMUX driver");
+MODULE_LICENSE("GPL");