mmc: atmel-mci: restore dma on AVR32

Commit ecb89f2f ("mmc: atmel-mci: remove compat for non DT board
when requesting dma chan") broke dma on AVR32 and any other boards not
using DT.  This restores a fallback mechanism for such cases.
Signed-off-by: Mans Rullgard <mans@mansr.com>
Acked-by: Hans-Christian Noren Egtvedt <egtvedt@samfundet.no>
Acked-by: Ludovic Desroches <ludovic.desroches@atmel.com>
Acked-by: Ulf Hansson <ulf.hansson@linaro.org>

arch/avr32/mach-at32ap/at32ap700x.c

@@ -1321,6 +1321,21 @@ static struct clk atmel_mci0_pclk = {
 	.index		= 9,
 };
 
+static bool at32_mci_dma_filter(struct dma_chan *chan, void *pdata)
+{
+	struct mci_dma_data *sl = pdata;
+
+	if (!sl)
+		return false;
+
+	if (find_slave_dev(sl) == chan->device->dev) {
+		chan->private = slave_data_ptr(sl);
+		return true;
+	}
+
+	return false;
+}
+
 struct platform_device *__init
 at32_add_device_mci(unsigned int id, struct mci_platform_data *data)
 {
@@ -1355,6 +1370,7 @@ at32_add_device_mci(unsigned int id, struct mci_platform_data *data)
 	slave->sdata.dst_master = 0;
 
 	data->dma_slave = slave;
+	data->dma_filter = at32_mci_dma_filter;
 
 	if (platform_device_add_data(pdev, data,
 				sizeof(struct mci_platform_data)))

drivers/mmc/host/atmel-mci.c

@@ -2280,6 +2280,23 @@ static int atmci_configure_dma(struct atmel_mci *host)
 {
 	host->dma.chan = dma_request_slave_channel_reason(&host->pdev->dev,
 							"rxtx");
+
+	if (PTR_ERR(host->dma.chan) == -ENODEV) {
+		struct mci_platform_data *pdata = host->pdev->dev.platform_data;
+		dma_cap_mask_t mask;
+
+		if (!pdata->dma_filter)
+			return -ENODEV;
+
+		dma_cap_zero(mask);
+		dma_cap_set(DMA_SLAVE, mask);
+
+		host->dma.chan = dma_request_channel(mask, pdata->dma_filter,
+						     pdata->dma_slave);
+		if (!host->dma.chan)
+			host->dma.chan = ERR_PTR(-ENODEV);
+	}
+
 	if (IS_ERR(host->dma.chan))
 		return PTR_ERR(host->dma.chan);
 

include/linux/atmel-mci.h

@@ -2,6 +2,7 @@
 #define __LINUX_ATMEL_MCI_H
 
 #include <linux/types.h>
+#include <linux/dmaengine.h>
 
 #define ATMCI_MAX_NR_SLOTS	2
 
@@ -37,6 +38,7 @@ struct mci_slot_pdata {
  */
 struct mci_platform_data {
 	struct mci_dma_data	*dma_slave;
+	dma_filter_fn		dma_filter;
 	struct mci_slot_pdata	slot[ATMCI_MAX_NR_SLOTS];
 };