ARM: dma: add /proc/dma support to arch/arm/kernel/dma.c

We have our own private implementation for ISA-like DMA which has been
missing exposure via the /proc/dma interface.  Add support for this.
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>

arch/arm/kernel/dma.c

@@ -16,6 +16,8 @@
 #include <linux/spinlock.h>
 #include <linux/errno.h>
 #include <linux/scatterlist.h>
+#include <linux/seq_file.h>
+#include <linux/proc_fs.h>
 
 #include <asm/dma.h>
 
@@ -264,3 +266,37 @@ int get_dma_residue(unsigned int chan)
 	return ret;
 }
 EXPORT_SYMBOL(get_dma_residue);
+
+#ifdef CONFIG_PROC_FS
+static int proc_dma_show(struct seq_file *m, void *v)
+{
+	int i;
+
+	for (i = 0 ; i < MAX_DMA_CHANNELS ; i++) {
+		dma_t *dma = dma_channel(i);
+		if (dma && dma->lock)
+			seq_printf(m, "%2d: %s\n", i, dma->device_id);
+	}
+	return 0;
+}
+
+static int proc_dma_open(struct inode *inode, struct file *file)
+{
+	return single_open(file, proc_dma_show, NULL);
+}
+
+static const struct file_operations proc_dma_operations = {
+	.open		= proc_dma_open,
+	.read		= seq_read,
+	.llseek		= seq_lseek,
+	.release	= single_release,
+};
+
+static int __init proc_dma_init(void)
+{
+	proc_create("dma", 0, NULL, &proc_dma_operations);
+	return 0;
+}
+
+__initcall(proc_dma_init);
+#endif