usb: musb: ux500: attempt to find channels by name before using pdata

If we can ever get to a state where we can solely search for DMA channels
by name, this will almost completely alleviate the requirement to pass
copious amounts of information though platform data. Here we take the
first step towards this. The next step will be to enable Device Tree
complete with name<->event_line mapping.

Cc: [e-mail]
Acked-by: Felipe Balbi <[e-mail]>
Acked-by: Fabio Baltieri <[e-mail]>
Signed-off-by: Lee Jones <[e-mail]>
Signed-off-by: Linus Walleij <[e-mail]>

drivers/usb/musb/ux500_dma.c

···
 #include <linux/platform_data/usb-musb-ux500.h>
 #include "musb_core.h"
 
+static const char *iep_chan_names[] = { "iep_1_9", "iep_2_10", "iep_3_11", "iep_4_12",
+					"iep_5_13", "iep_6_14", "iep_7_15", "iep_8" };
+static const char *oep_chan_names[] = { "oep_1_9", "oep_2_10", "oep_3_11", "oep_4_12",
+					"oep_5_13", "oep_6_14", "oep_7_15", "oep_8" };
+
 struct ux500_dma_channel {
 	struct dma_channel channel;
 	struct ux500_dma_controller *controller;
···
 	struct musb_hdrc_platform_data *plat = dev->platform_data;
 	struct ux500_musb_board_data *data;
 	struct dma_channel *dma_channel = NULL;
+	char **chan_names;
 	u32 ch_num;
 	u8 dir;
 	u8 is_tx = 0;
···
 	/* Prepare the loop for RX channels */
 	channel_array = controller->rx_channel;
 	param_array = data ? data->dma_rx_param_array : NULL;
+	chan_names = (char **)iep_chan_names;
 
 	for (dir = 0; dir < 2; dir++) {
 		for (ch_num = 0;
···
 			dma_channel->status = MUSB_DMA_STATUS_FREE;
 			dma_channel->max_len = SZ_16M;
 
-			ux500_channel->dma_chan = dma_request_channel(mask,
-							data->dma_filter,
-							param_array[ch_num]);
+			ux500_channel->dma_chan =
+				dma_request_slave_channel(dev, chan_names[ch_num]);
+
+			if (!ux500_channel->dma_chan)
+				ux500_channel->dma_chan =
+					dma_request_channel(mask,
+							    data->dma_filter,
+							    param_array[ch_num]);
+
 			if (!ux500_channel->dma_chan) {
 				ERR("Dma pipe allocation error dir=%d ch=%d\n",
 					dir, ch_num);
···
 		/* Prepare the loop for TX channels */
 		channel_array = controller->tx_channel;
 		param_array = data ? data->dma_tx_param_array : NULL;
+		chan_names = (char **)oep_chan_names;
 		is_tx = 1;
 	}