// SPDX-License-Identifier: GPL-2.0
/*
 * SH7760 DMABRG IRQ handling
 *
 * (c) 2007 MSC Vertriebsges.m.b.H, Manuel Lauss <mlau@msc-ge.com>
 */

#include <linux/interrupt.h>
#include <linux/kernel.h>
#include <linux/slab.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 occurred.
 *
 * 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 = __raw_readl(DMABRGCR);
        __raw_writel(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 = __raw_readl(DMABRGCR);
        dcr &= ~(1 << ((dmairq > 1) ? dmairq + 22 : dmairq + 8));
        __raw_writel(dcr, DMABRGCR);
}

static void dmabrg_enable_irq(unsigned int dmairq)
{
        unsigned long dcr;
        dcr = __raw_readl(DMABRGCR);
        dcr |= (1 << ((dmairq > 1) ? dmairq + 22 : dmairq + 8));
        __raw_writel(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_objs(struct dmabrg_handler, 10);
        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

        __raw_writel(0, DMABRGCR);
        __raw_writel(0, DMACHCR0);
        __raw_writel(0x94000000, DMARSRA);      /* enable DMABRG in DMAC 0 */

        /* enable DMABRG mode, enable the DMAC */
        or = __raw_readl(DMAOR);
        __raw_writel(or | DMAOR_BRG | DMAOR_DMEN, DMAOR);

        ret = request_irq(DMABRGI0, dmabrg_irq, 0,
                        "DMABRG USB address error", NULL);
        if (ret)
                goto out0;

        ret = request_irq(DMABRGI1, dmabrg_irq, 0,
                        "DMABRG Transfer End", NULL);
        if (ret)
                goto out1;

        ret = request_irq(DMABRGI2, dmabrg_irq, 0,
                        "DMABRG Transfer Half", NULL);
        if (ret == 0)
                return ret;

        free_irq(DMABRGI1, NULL);
out1:   free_irq(DMABRGI0, NULL);
out0:   kfree(dmabrg_handlers);
        return ret;
}
subsys_initcall(dmabrg_init);