[PATCH 2/5] dmaengine: Add STM32 DMAMUX driver

[M'boumba Cedric Madianga <cedric.madianga@gmail.com>]

This patch implements the STM32 DMAMUX driver

Signed-off-by: M'boumba Cedric Madianga <cedric.madianga@gmail.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
+	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@gmail.com>
+ *
+ * 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);
+	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);
-- 
1.9.1