DMA: shdma: add DT support

This patch adds Device Tree support to the shdma driver. No special DT
properties are used, only standard DMA DT bindings are implemented. Since
shdma controllers reside on SoCs, their configuration is SoC-specific and
shall be passed to the driver from the SoC platform data, using the
auxdata procedure.

Signed-off-by: Guennadi Liakhovetski <g.liakhovetski+renesas@gmail.com>
Acked-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Vinod Koul <vinod.koul@intel.com>

Documentation/devicetree/bindings/dma/shdma.txt

@@ -0,0 +1,75 @@
+* SHDMA Device Tree bindings
+
+Sh-/r-mobile and r-car systems often have multiple identical DMA controller
+instances, capable of serving any of a common set of DMA slave devices, using
+the same configuration. To describe this topology we require all compatible
+SHDMA DT nodes to be placed under a DMA multiplexer node. All such compatible
+DMAC instances have the same number of channels and use the same DMA
+descriptors. Therefore respective DMA DT bindings can also all be placed in the
+multiplexer node. Even if there is only one such DMAC instance on a system, it
+still has to be placed under such a multiplexer node.
+
+* DMA multiplexer
+
+Required properties:
+- compatible:	should be "renesas,shdma-mux"
+- #dma-cells:	should be <1>, see "dmas" property below
+
+Optional properties (currently unused):
+- dma-channels:	number of DMA channels
+- dma-requests:	number of DMA request signals
+
+* DMA controller
+
+Required properties:
+- compatible:	should be "renesas,shdma"
+
+Example:
+	dmac: dma-mux0 {
+		compatible = "renesas,shdma-mux";
+		#dma-cells = <1>;
+		dma-channels = <6>;
+		dma-requests = <256>;
+		reg = <0 0>;	/* Needed for AUXDATA */
+		#address-cells = <1>;
+		#size-cells = <1>;
+		ranges;
+
+		dma0: shdma@fe008020 {
+			compatible = "renesas,shdma";
+			reg = <0xfe008020 0x270>,
+				<0xfe009000 0xc>;
+			interrupt-parent = <&gic>;
+			interrupts = <0 34 4
+					0 28 4
+					0 29 4
+					0 30 4
+					0 31 4
+					0 32 4
+					0 33 4>;
+			interrupt-names = "error",
+					"ch0", "ch1", "ch2", "ch3",
+					"ch4", "ch5";
+		};
+
+		dma1: shdma@fe018020 {
+			...
+		};
+
+		dma2: shdma@fe028020 {
+			...
+		};
+	};
+
+* DMA client
+
+Required properties:
+- dmas:		a list of <[DMA multiplexer phandle] [MID/RID value]> pairs,
+		where MID/RID values are fixed handles, specified in the SoC
+		manual
+- dma-names:	a list of DMA channel names, one per "dmas" entry
+
+Example:
+	dmas = <&dmac 0xd1
+		&dmac 0xd2>;
+	dma-names = "tx", "rx";

drivers/dma/sh/Makefile

@@ -1,3 +1,3 @@
-obj-$(CONFIG_SH_DMAE_BASE) += shdma-base.o
+obj-$(CONFIG_SH_DMAE_BASE) += shdma-base.o shdma-of.o
 obj-$(CONFIG_SH_DMAE) += shdma.o
 obj-$(CONFIG_SUDMAC) += sudmac.o

drivers/dma/sh/shdma-base.c

@@ -175,7 +175,18 @@ static int shdma_setup_slave(struct shdma_chan *schan, int slave_id)
 {
 	struct shdma_dev *sdev = to_shdma_dev(schan->dma_chan.device);
 	const struct shdma_ops *ops = sdev->ops;
-	int ret;
+	int ret, match;
+
+	if (schan->dev->of_node) {
+		match = schan->hw_req;
+		ret = ops->set_slave(schan, match, true);
+		if (ret < 0)
+			return ret;
+
+		slave_id = schan->slave_id;
+	} else {
+		match = slave_id;
+	}
 
 	if (slave_id < 0 || slave_id >= slave_num)
 		return -EINVAL;
@@ -183,7 +194,7 @@ static int shdma_setup_slave(struct shdma_chan *schan, int slave_id)
 	if (test_and_set_bit(slave_id, shdma_slave_used))
 		return -EBUSY;
 
-	ret = ops->set_slave(schan, slave_id, false);
+	ret = ops->set_slave(schan, match, false);
 	if (ret < 0) {
 		clear_bit(slave_id, shdma_slave_used);
 		return ret;
@@ -206,23 +217,26 @@ static int shdma_setup_slave(struct shdma_chan *schan, int slave_id)
  * services would have to provide their own filters, which first would check
  * the device driver, similar to how other DMAC drivers, e.g., sa11x0-dma.c, do
  * this, and only then, in case of a match, call this common filter.
+ * NOTE 2: This filter function is also used in the DT case by shdma_of_xlate().
+ * In that case the MID-RID value is used for slave channel filtering and is
+ * passed to this function in the "arg" parameter.
  */
 bool shdma_chan_filter(struct dma_chan *chan, void *arg)
 {
 	struct shdma_chan *schan = to_shdma_chan(chan);
 	struct shdma_dev *sdev = to_shdma_dev(schan->dma_chan.device);
 	const struct shdma_ops *ops = sdev->ops;
-	int slave_id = (int)arg;
+	int match = (int)arg;
 	int ret;
 
-	if (slave_id < 0)
+	if (match < 0)
 		/* No slave requested - arbitrary channel */
 		return true;
 
-	if (slave_id >= slave_num)
+	if (!schan->dev->of_node && match >= slave_num)
 		return false;
 
-	ret = ops->set_slave(schan, slave_id, true);
+	ret = ops->set_slave(schan, match, true);
 	if (ret < 0)
 		return false;
 

drivers/dma/sh/shdma-of.c

@@ -0,0 +1,82 @@
+/*
+ * SHDMA Device Tree glue
+ *
+ * Copyright (C) 2013 Renesas Electronics Inc.
+ * Author: Guennadi Liakhovetski <g.liakhovetski@gmx.de>
+ *
+ * This is free software; you can redistribute it and/or modify
+ * it under the terms of version 2 of the GNU General Public License as
+ * published by the Free Software Foundation.
+ */
+
+#include <linux/dmaengine.h>
+#include <linux/module.h>
+#include <linux/of.h>
+#include <linux/of_dma.h>
+#include <linux/of_platform.h>
+#include <linux/platform_device.h>
+#include <linux/shdma-base.h>
+
+#define to_shdma_chan(c) container_of(c, struct shdma_chan, dma_chan)
+
+static struct dma_chan *shdma_of_xlate(struct of_phandle_args *dma_spec,
+				       struct of_dma *ofdma)
+{
+	u32 id = dma_spec->args[0];
+	dma_cap_mask_t mask;
+	struct dma_chan *chan;
+
+	if (dma_spec->args_count != 1)
+		return NULL;
+
+	dma_cap_zero(mask);
+	/* Only slave DMA channels can be allocated via DT */
+	dma_cap_set(DMA_SLAVE, mask);
+
+	chan = dma_request_channel(mask, shdma_chan_filter, (void *)id);
+	if (chan)
+		to_shdma_chan(chan)->hw_req = id;
+
+	return chan;
+}
+
+static int shdma_of_probe(struct platform_device *pdev)
+{
+	const struct of_dev_auxdata *lookup = pdev->dev.platform_data;
+	int ret;
+
+	if (!lookup)
+		return -EINVAL;
+
+	ret = of_dma_controller_register(pdev->dev.of_node,
+					 shdma_of_xlate, pdev);
+	if (ret < 0)
+		return ret;
+
+	ret = of_platform_populate(pdev->dev.of_node, NULL, lookup, &pdev->dev);
+	if (ret < 0)
+		of_dma_controller_free(pdev->dev.of_node);
+
+	return ret;
+}
+
+static const struct of_device_id shdma_of_match[] = {
+	{ .compatible = "renesas,shdma-mux", },
+	{ }
+};
+MODULE_DEVICE_TABLE(of, sh_dmae_of_match);
+
+static struct platform_driver shdma_of = {
+	.driver		= {
+		.owner	= THIS_MODULE,
+		.name	= "shdma-of",
+		.of_match_table = shdma_of_match,
+	},
+	.probe		= shdma_of_probe,
+};
+
+module_platform_driver(shdma_of);
+
+MODULE_LICENSE("GPL v2");
+MODULE_DESCRIPTION("SH-DMA driver DT glue");
+MODULE_AUTHOR("Guennadi Liakhovetski <g.liakhovetski@gmx.de>");

drivers/dma/sh/shdma.c

@@ -301,20 +301,32 @@ static void sh_dmae_setup_xfer(struct shdma_chan *schan,
 	}
 }
 
+/*
+ * Find a slave channel configuration from the contoller list by either a slave
+ * ID in the non-DT case, or by a MID/RID value in the DT case
+ */
 static const struct sh_dmae_slave_config *dmae_find_slave(
-	struct sh_dmae_chan *sh_chan, int slave_id)
+	struct sh_dmae_chan *sh_chan, int match)
 {
 	struct sh_dmae_device *shdev = to_sh_dev(sh_chan);
 	struct sh_dmae_pdata *pdata = shdev->pdata;
 	const struct sh_dmae_slave_config *cfg;
 	int i;
 
-	if (slave_id >= SH_DMA_SLAVE_NUMBER)
-		return NULL;
+	if (!sh_chan->shdma_chan.dev->of_node) {
+		if (match >= SH_DMA_SLAVE_NUMBER)
+			return NULL;
 
-	for (i = 0, cfg = pdata->slave; i < pdata->slave_num; i++, cfg++)
-		if (cfg->slave_id == slave_id)
-			return cfg;
+		for (i = 0, cfg = pdata->slave; i < pdata->slave_num; i++, cfg++)
+			if (cfg->slave_id == match)
+				return cfg;
+	} else {
+		for (i = 0, cfg = pdata->slave; i < pdata->slave_num; i++, cfg++)
+			if (cfg->mid_rid == match) {
+				sh_chan->shdma_chan.slave_id = cfg->slave_id;
+				return cfg;
+			}
+	}
 
 	return NULL;
 }
@@ -920,11 +932,18 @@ static int sh_dmae_remove(struct platform_device *pdev)
 	return 0;
 }
 
+static const struct of_device_id sh_dmae_of_match[] = {
+	{ .compatible = "renesas,shdma", },
+	{ }
+};
+MODULE_DEVICE_TABLE(of, sh_dmae_of_match);
+
 static struct platform_driver sh_dmae_driver = {
 	.driver 	= {
 		.owner	= THIS_MODULE,
 		.pm	= &sh_dmae_pm,
 		.name	= SH_DMAE_DRV_NAME,
+		.of_match_table = sh_dmae_of_match,
 	},
 	.remove		= sh_dmae_remove,
 	.shutdown	= sh_dmae_shutdown,

include/linux/shdma-base.h

@@ -68,6 +68,8 @@ struct shdma_chan {
 	int id;				/* Raw id of this channel */
 	int irq;			/* Channel IRQ */
 	int slave_id;			/* Client ID for slave DMA */
+	int hw_req;			/* DMA request line for slave DMA - same
+					 * as MID/RID, used with DT */
 	enum shdma_pm_state pm_state;
 };