sh: SH7760 DMABRG support.

The DMABRG is a special DMA unit within the SH7760 which does data
transfers from main memory to Audio units and USB shared memory.
It has 3 IRQ lines which generate 10 events, which have to be masked
unmasked and acked in a single 32bit register. It works independently
from the tradition SH DMAC, but blocks usage of DMAC channel 0.

This patch adds 2 functions to associate callbacks with DMABRG events
and initialization.

Signed-off-by: Manuel Lauss <[e-mail]>
Signed-off-by: Paul Mundt <[e-mail]>

arch/sh/drivers/Makefile

···
 # Makefile for the Linux SuperH-specific device drivers.
 #
 
+obj-y		+= dma/
+
 obj-$(CONFIG_PCI)		+= pci/
-obj-$(CONFIG_SH_DMA)		+= dma/
 obj-$(CONFIG_SUPERHYWAY)	+= superhyway/
 obj-$(CONFIG_PUSH_SWITCH)	+= push-switch.o
 obj-$(CONFIG_HEARTBEAT)		+= heartbeat.o

arch/sh/drivers/dma/Kconfig

···
 menu "DMA support"
 
-config SH_DMA
-	bool "DMA controller (DMAC) support"
-	help
-	  Selecting this option will provide same API as PC's Direct Memory
-	  Access Controller(8237A) for SuperH DMAC.
+config SH_DMA_API
+	bool
 
-	  If unsure, say N.
+config SH_DMA
+	bool "SuperH on-chip DMA controller (DMAC) support"
+	select SH_DMA_API
+	default n
 
 config NR_ONCHIP_DMA_CHANNELS
 	depends on SH_DMA
···
 	  This allows the specification of the dual address dma channel,
 	  in case channel 3 is unavailable. On the SH4, channels 1,2, and 3
 	  are dual-address capable.
+
+config SH_DMABRG
+	bool "SH7760 DMABRG support"
+	depends on CPU_SUBTYPE_SH7760
+	help
+	  The DMABRG does data transfers from main memory to Audio/USB units
+	  of the SH7760.
+	  Say Y if you want to use Audio/USB DMA on your SH7760 board.
 
 endmenu

arch/sh/drivers/dma/Makefile

···
 # Makefile for the SuperH DMA specific kernel interface routines under Linux.
 #
 
-obj-y				+= dma-api.o
+obj-$(CONFIG_SH_DMA_API)	+= dma-api.o dma-sysfs.o
 obj-$(CONFIG_ISA_DMA_API)	+= dma-isa.o
-obj-$(CONFIG_SYSFS)		+= dma-sysfs.o
 obj-$(CONFIG_SH_DMA)		+= dma-sh.o
 obj-$(CONFIG_SH_DREAMCAST)	+= dma-pvr2.o dma-g2.o
+obj-$(CONFIG_SH_DMABRG)		+= dmabrg.o

arch/sh/drivers/dma/dmabrg.c

···
+/*
+ * SH7760 DMABRG IRQ handling
+ *
+ * (c) 2007 MSC Vertriebsges.m.b.H, Manuel Lauss <[e-mail]>
+ *  licensed under the GPLv2.
+ *
+ */
+
+#include <linux/interrupt.h>
+#include <linux/kernel.h>
+#include <asm/dma.h>
+#include <asm/dmabrg.h>
+#include <asm/io.h>
+
+/*
+ * The DMABRG is a special DMA unit within the SH7760. It does transfers
+ * from USB-SRAM/Audio units to main memory (and also the LCDC; but that
+ * part is sensibly placed  in the LCDC  registers and requires no irqs)
+ * It has 3 IRQ lines which trigger 10 events, and works independently
+ * from the traditional SH DMAC (although it blocks usage of DMAC 0)
+ *
+ * BRGIRQID   | component | dir | meaning      | source
+ * -----------------------------------------------------
+ *     0      | USB-DMA   | ... | xfer done    | DMABRGI1
+ *     1      | USB-UAE   | ... | USB addr err.| DMABRGI0
+ *     2      | HAC0/SSI0 | play| all done     | DMABRGI1
+ *     3      | HAC0/SSI0 | play| half done    | DMABRGI2
+ *     4      | HAC0/SSI0 | rec | all done     | DMABRGI1
+ *     5      | HAC0/SSI0 | rec | half done    | DMABRGI2
+ *     6      | HAC1/SSI1 | play| all done     | DMABRGI1
+ *     7      | HAC1/SSI1 | play| half done    | DMABRGI2
+ *     8      | HAC1/SSI1 | rec | all done     | DMABRGI1
+ *     9      | HAC1/SSI1 | rec | half done    | DMABRGI2
+ *
+ * all can be enabled/disabled in the DMABRGCR register,
+ * as well as checked if they occured.
+ *
+ * DMABRGI0 services  USB  DMA  Address  errors,  but it still must be
+ * enabled/acked in the DMABRGCR register.  USB-DMA complete indicator
+ * is grouped together with the audio buffer end indicators, too bad...
+ *
+ * DMABRGCR:	Bits 31-24: audio-dma ENABLE flags,
+ *		Bits 23-16: audio-dma STATUS flags,
+ *		Bits  9-8:  USB error/xfer ENABLE,
+ *		Bits  1-0:  USB error/xfer STATUS.
+ *	Ack an IRQ by writing 0 to the STATUS flag.
+ *	Mask IRQ by writing 0 to ENABLE flag.
+ *
+ * Usage is almost like with any other IRQ:
+ *  dmabrg_request_irq(BRGIRQID, handler, data)
+ *  dmabrg_free_irq(BRGIRQID)
+ *
+ * handler prototype:  void brgirqhandler(void *data)
+ */
+
+#define DMARSRA		0xfe090000
+#define DMAOR		0xffa00040
+#define DMACHCR0	0xffa0000c
+#define DMABRGCR	0xfe3c0000
+
+#define DMAOR_BRG	0x0000c000
+#define DMAOR_DMEN	0x00000001
+
+#define DMABRGI0	68
+#define DMABRGI1	69
+#define DMABRGI2	70
+
+struct dmabrg_handler {
+	void (*handler)(void *);
+	void *data;
+} *dmabrg_handlers;
+
+static inline void dmabrg_call_handler(int i)
+{
+	dmabrg_handlers[i].handler(dmabrg_handlers[i].data);
+}
+
+/*
+ * main DMABRG irq handler. It acks irqs and then
+ * handles every set and unmasked bit sequentially.
+ * No locking and no validity checks; it should be
+ * as fast as possible (audio!)
+ */
+static irqreturn_t dmabrg_irq(int irq, void *data)
+{
+	unsigned long dcr;
+	unsigned int i;
+
+	dcr = ctrl_inl(DMABRGCR);
+	ctrl_outl(dcr & ~0x00ff0003, DMABRGCR);	/* ack all */
+	dcr &= dcr >> 8;	/* ignore masked */
+
+	/* USB stuff, get it out of the way first */
+	if (dcr & 1)
+		dmabrg_call_handler(DMABRGIRQ_USBDMA);
+	if (dcr & 2)
+		dmabrg_call_handler(DMABRGIRQ_USBDMAERR);
+
+	/* Audio */
+	dcr >>= 16;
+	while (dcr) {
+		i = __ffs(dcr);
+		dcr &= dcr - 1;
+		dmabrg_call_handler(i + DMABRGIRQ_A0TXF);
+	}
+	return IRQ_HANDLED;
+}
+
+static void dmabrg_disable_irq(unsigned int dmairq)
+{
+	unsigned long dcr;
+	dcr = ctrl_inl(DMABRGCR);
+	dcr &= ~(1 << ((dmairq > 1) ? dmairq + 22 : dmairq + 8));
+	ctrl_outl(dcr, DMABRGCR);
+}
+
+static void dmabrg_enable_irq(unsigned int dmairq)
+{
+	unsigned long dcr;
+	dcr = ctrl_inl(DMABRGCR);
+	dcr |= (1 << ((dmairq > 1) ? dmairq + 22 : dmairq + 8));
+	ctrl_outl(dcr, DMABRGCR);
+}
+
+int dmabrg_request_irq(unsigned int dmairq, void(*handler)(void*),
+		       void *data)
+{
+	if ((dmairq > 9) || !handler)
+		return -ENOENT;
+	if (dmabrg_handlers[dmairq].handler)
+		return -EBUSY;
+
+	dmabrg_handlers[dmairq].handler = handler;
+	dmabrg_handlers[dmairq].data = data;
+	
+	dmabrg_enable_irq(dmairq);
+	return 0;
+}
+EXPORT_SYMBOL_GPL(dmabrg_request_irq);
+
+void dmabrg_free_irq(unsigned int dmairq)
+{
+	if (likely(dmairq < 10)) {
+		dmabrg_disable_irq(dmairq);
+		dmabrg_handlers[dmairq].handler = NULL;
+		dmabrg_handlers[dmairq].data = NULL;
+	}
+}
+EXPORT_SYMBOL_GPL(dmabrg_free_irq);
+
+static int __init dmabrg_init(void)
+{
+	unsigned long or;
+	int ret;
+
+	dmabrg_handlers = kzalloc(10 * sizeof(struct dmabrg_handler),
+				  GFP_KERNEL);
+	if (!dmabrg_handlers)
+		return -ENOMEM;
+
+#ifdef CONFIG_SH_DMA
+	/* request DMAC channel 0 before anyone else can get it */
+	ret = request_dma(0, "DMAC 0 (DMABRG)");
+	if (ret < 0)
+		printk(KERN_INFO "DMABRG: DMAC ch0 not reserved!\n");
+#endif
+
+	ctrl_outl(0, DMABRGCR);
+	ctrl_outl(0, DMACHCR0);
+	ctrl_outl(0x94000000, DMARSRA);	/* enable DMABRG in DMAC 0 */
+
+	/* enable DMABRG mode, enable the DMAC */
+	or = ctrl_inl(DMAOR);
+	ctrl_outl(or | DMAOR_BRG | DMAOR_DMEN, DMAOR);
+
+	ret = request_irq(DMABRGI0, dmabrg_irq, IRQF_DISABLED,
+			"DMABRG USB address error", NULL);
+	if (ret)
+		goto out0;
+
+	ret = request_irq(DMABRGI1, dmabrg_irq, IRQF_DISABLED,
+			"DMABRG Transfer End", NULL);
+	if (ret)
+		goto out1;
+
+	ret = request_irq(DMABRGI2, dmabrg_irq, IRQF_DISABLED,
+			"DMABRG Transfer Half", NULL);
+	if (ret == 0)
+		return ret;
+
+	free_irq(DMABRGI1, 0);
+out1:	free_irq(DMABRGI0, 0);
+out0:	kfree(dmabrg_handlers);
+	return ret;
+}
+subsys_initcall(dmabrg_init);

include/asm-sh/dmabrg.h

···
+/*
+ * SH7760 DMABRG (USB/Audio) support
+ */
+
+#ifndef _DMABRG_H_
+#define _DMABRG_H_
+
+/* IRQ sources */
+#define DMABRGIRQ_USBDMA	0
+#define DMABRGIRQ_USBDMAERR	1
+#define DMABRGIRQ_A0TXF		2
+#define DMABRGIRQ_A0TXH		3
+#define DMABRGIRQ_A0RXF		4
+#define DMABRGIRQ_A0RXH		5
+#define DMABRGIRQ_A1TXF		6
+#define DMABRGIRQ_A1TXH		7
+#define DMABRGIRQ_A1RXF		8
+#define DMABRGIRQ_A1RXH		9
+
+extern int dmabrg_request_irq(unsigned int, void(*)(void *), void *);
+extern void dmabrg_free_irq(unsigned int);
+
+#endif