dmaengine: dw_dmac: move to generic DMA binding

The original device tree binding for this driver, from Viresh Kumar
unfortunately conflicted with the generic DMA binding, and did not allow
to completely seperate slave device configuration from the controller.

This is an attempt to replace it with an implementation of the generic
binding, but it is currently completely untested, because I do not have
any hardware with this particular controller.

The patch applies on top of the slave-dma tree, which contains both the base
support for the generic DMA binding, as well as the earlier attempt from
Viresh. Both of these are currently not merged upstream however.

This version incorporates feedback from Viresh Kumar, Andy Shevchenko
and Russell King.

Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Acked-by: Viresh Kumar <viresh.kumar@linaro.org>
Acked-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Cc: Vinod Koul <vinod.koul@linux.intel.com>
Cc: devicetree-discuss@lists.ozlabs.org
Cc: linux-arm-kernel@lists.infradead.org
Signed-off-by: Vinod Koul <vinod.koul@intel.com>

2 files changed, 75 insertions, 77 deletions

diff --git a/drivers/dma/dw_dmac.c b/drivers/dma/dw_dmac.c
index 4c83f18..c3159ab 100644
--- a/drivers/dma/dw_dmac.c
+++ b/drivers/dma/dw_dmac.c
@@ -19,6 +19,7 @@
 #include <linux/interrupt.h>
 #include <linux/io.h>
 #include <linux/of.h>
+#include <linux/of_dma.h>
 #include <linux/mm.h>
 #include <linux/module.h>
 #include <linux/platform_device.h>
@@ -170,7 +171,13 @@ static void dwc_initialize(struct dw_dma_chan *dwc)
 	if (dwc->initialized == true)
 		return;
 
-	if (dws) {
+	if (dws && dws->cfg_hi == ~0 && dws->cfg_lo == ~0) {
+		/* autoconfigure based on request line from DT */
+		if (dwc->direction == DMA_MEM_TO_DEV)
+			cfghi = DWC_CFGH_DST_PER(dwc->request_line);
+		else if (dwc->direction == DMA_DEV_TO_MEM)
+			cfghi = DWC_CFGH_SRC_PER(dwc->request_line);
+	} else if (dws) {
 		/*
 		 * We need controller-specific data to set up slave
 		 * transfers.
@@ -1225,49 +1232,64 @@ static void dwc_free_chan_resources(struct dma_chan *chan)
 	dev_vdbg(chan2dev(chan), "%s: done\n", __func__);
 }
 
-bool dw_dma_generic_filter(struct dma_chan *chan, void *param)
+struct dw_dma_filter_args {
+	struct dw_dma *dw;
+	unsigned int req;
+	unsigned int src;
+	unsigned int dst;
+};
+
+static bool dw_dma_generic_filter(struct dma_chan *chan, void *param)
 {
+	struct dw_dma_chan *dwc = to_dw_dma_chan(chan);
 	struct dw_dma *dw = to_dw_dma(chan->device);
-	static struct dw_dma *last_dw;
-	static char *last_bus_id;
-	int i = -1;
+	struct dw_dma_filter_args *fargs = param;
+	struct dw_dma_slave *dws = &dwc->slave;
 
-	/*
-	 * dmaengine framework calls this routine for all channels of all dma
-	 * controller, until true is returned. If 'param' bus_id is not
-	 * registered with a dma controller (dw), then there is no need of
-	 * running below function for all channels of dw.
-	 *
-	 * This block of code does this by saving the parameters of last
-	 * failure. If dw and param are same, i.e. trying on same dw with
-	 * different channel, return false.
-	 */
-	if ((last_dw == dw) && (last_bus_id == param))
-		return false;
-	/*
-	 * Return true:
-	 * - If dw_dma's platform data is not filled with slave info, then all
-	 *   dma controllers are fine for transfer.
-	 * - Or if param is NULL
-	 */
-	if (!dw->sd || !param)
-		return true;
+	/* ensure the device matches our channel */
+        if (chan->device != &fargs->dw->dma)
+                return false;
 
-	while (++i < dw->sd_count) {
-		if (!strcmp(dw->sd[i].bus_id, param)) {
-			chan->private = &dw->sd[i];
-			last_dw = NULL;
-			last_bus_id = NULL;
+	dws->dma_dev	= dw->dma.dev;
+	dws->cfg_hi	= ~0;
+	dws->cfg_lo	= ~0;
+	dws->src_master	= fargs->src;
+	dws->dst_master	= fargs->dst;
 
-			return true;
-		}
-	}
+	dwc->request_line = fargs->req;
 
-	last_dw = dw;
-	last_bus_id = param;
-	return false;
+	chan->private = dws;
+
+	return true;
+}
+
+static struct dma_chan *dw_dma_xlate(struct of_phandle_args *dma_spec,
+					 struct of_dma *ofdma)
+{
+	struct dw_dma *dw = ofdma->of_dma_data;
+	struct dw_dma_filter_args fargs = {
+		.dw = dw,
+	};
+	dma_cap_mask_t cap;
+
+	if (dma_spec->args_count != 3)
+		return NULL;
+
+	fargs.req = be32_to_cpup(dma_spec->args+0);
+	fargs.src = be32_to_cpup(dma_spec->args+1);
+	fargs.dst = be32_to_cpup(dma_spec->args+2);
+
+	if (WARN_ON(fargs.req >= DW_DMA_MAX_NR_REQUESTS ||
+		    fargs.src >= dw->nr_masters ||
+		    fargs.dst >= dw->nr_masters))
+		return NULL;
+
+	dma_cap_zero(cap);
+	dma_cap_set(DMA_SLAVE, cap);
+
+	/* TODO: there should be a simpler way to do this */
+	return dma_request_channel(cap, dw_dma_generic_filter, &fargs);
 }
-EXPORT_SYMBOL(dw_dma_generic_filter);
 
 /* --------------------- Cyclic DMA API extensions -------------------- */
 
@@ -1553,9 +1575,8 @@ static void dw_dma_off(struct dw_dma *dw)
 static struct dw_dma_platform_data *
 dw_dma_parse_dt(struct platform_device *pdev)
 {
-	struct device_node *sn, *cn, *np = pdev->dev.of_node;
+	struct device_node *np = pdev->dev.of_node;
 	struct dw_dma_platform_data *pdata;
-	struct dw_dma_slave *sd;
 	u32 tmp, arr[4];
 
 	if (!np) {
@@ -1567,7 +1588,7 @@ dw_dma_parse_dt(struct platform_device *pdev)
 	if (!pdata)
 		return NULL;
 
-	if (of_property_read_u32(np, "nr_channels", &pdata->nr_channels))
+	if (of_property_read_u32(np, "dma-channels", &pdata->nr_channels))
 		return NULL;
 
 	if (of_property_read_bool(np, "is_private"))
@@ -1582,7 +1603,7 @@ dw_dma_parse_dt(struct platform_device *pdev)
 	if (!of_property_read_u32(np, "block_size", &tmp))
 		pdata->block_size = tmp;
 
-	if (!of_property_read_u32(np, "nr_masters", &tmp)) {
+	if (!of_property_read_u32(np, "dma-masters", &tmp)) {
 		if (tmp > 4)
 			return NULL;
 
@@ -1594,36 +1615,6 @@ dw_dma_parse_dt(struct platform_device *pdev)
 		for (tmp = 0; tmp < pdata->nr_masters; tmp++)
 			pdata->data_width[tmp] = arr[tmp];
 
-	/* parse slave data */
-	sn = of_find_node_by_name(np, "slave_info");
-	if (!sn)
-		return pdata;
-
-	/* calculate number of slaves */
-	tmp = of_get_child_count(sn);
-	if (!tmp)
-		return NULL;
-
-	sd = devm_kzalloc(&pdev->dev, sizeof(*sd) * tmp, GFP_KERNEL);
-	if (!sd)
-		return NULL;
-
-	pdata->sd = sd;
-	pdata->sd_count = tmp;
-
-	for_each_child_of_node(sn, cn) {
-		sd->dma_dev = &pdev->dev;
-		of_property_read_string(cn, "bus_id", &sd->bus_id);
-		of_property_read_u32(cn, "cfg_hi", &sd->cfg_hi);
-		of_property_read_u32(cn, "cfg_lo", &sd->cfg_lo);
-		if (!of_property_read_u32(cn, "src_master", &tmp))
-			sd->src_master = tmp;
-
-		if (!of_property_read_u32(cn, "dst_master", &tmp))
-			sd->dst_master = tmp;
-		sd++;
-	}
-
 	return pdata;
 }
 #else
@@ -1704,8 +1695,6 @@ static int dw_probe(struct platform_device *pdev)
 	clk_prepare_enable(dw->clk);
 
 	dw->regs = regs;
-	dw->sd = pdata->sd;
-	dw->sd_count = pdata->sd_count;
 
 	/* get hardware configuration parameters */
 	if (autocfg) {
@@ -1836,6 +1825,14 @@ static int dw_probe(struct platform_device *pdev)
 
 	dma_async_device_register(&dw->dma);
 
+	if (pdev->dev.of_node) {
+		err = of_dma_controller_register(pdev->dev.of_node,
+						 dw_dma_xlate, dw);
+		if (err && err != -ENODEV)
+			dev_err(&pdev->dev,
+				"could not register of_dma_controller\n");
+	}
+
 	return 0;
 }
 
@@ -1844,6 +1841,8 @@ static int __devexit dw_remove(struct platform_device *pdev)
 	struct dw_dma		*dw = platform_get_drvdata(pdev);
 	struct dw_dma_chan	*dwc, *_dwc;
 
+	if (pdev->dev.of_node)
+		of_dma_controller_free(pdev->dev.of_node);
 	dw_dma_off(dw);
 	dma_async_device_unregister(&dw->dma);
 
diff --git a/drivers/dma/dw_dmac_regs.h b/drivers/dma/dw_dmac_regs.h
index 88dd8eb..cf0ce5c 100644
--- a/drivers/dma/dw_dmac_regs.h
+++ b/drivers/dma/dw_dmac_regs.h
@@ -13,6 +13,7 @@
 #include <linux/dw_dmac.h>
 
 #define DW_DMA_MAX_NR_CHANNELS	8
+#define DW_DMA_MAX_NR_REQUESTS	16
 
 /* flow controller */
 enum dw_dma_fc {
@@ -211,6 +212,8 @@ struct dw_dma_chan {
 	/* hardware configuration */
 	unsigned int		block_size;
 	bool			nollp;
+	unsigned int		request_line;
+	struct dw_dma_slave	slave;
 
 	/* configuration passed via DMA_SLAVE_CONFIG */
 	struct dma_slave_config dma_sconfig;
@@ -239,10 +242,6 @@ struct dw_dma {
 	struct tasklet_struct	tasklet;
 	struct clk		*clk;
 
-	/* slave information */
-	struct dw_dma_slave	*sd;
-	unsigned int		sd_count;
-
 	u8			all_chan_mask;
 
 	/* hardware configuration */