// SPDX-License-Identifier: GPL-2.0+
/*
 * Renesas SuperH DMA Engine support
 *
 * base is drivers/dma/flsdma.c
 *
 * Copyright (C) 2011-2012 Guennadi Liakhovetski <g.liakhovetski@gmx.de>
 * Copyright (C) 2009 Nobuhiro Iwamatsu <iwamatsu.nobuhiro@renesas.com>
 * Copyright (C) 2009 Renesas Solutions, Inc. All rights reserved.
 * Copyright (C) 2007 Freescale Semiconductor, Inc. All rights reserved.
 *
 * - DMA of SuperH does not have Hardware DMA chain mode.
 * - MAX DMA size is 16MB.
 *
 */

#include <linux/delay.h>
#include <linux/dmaengine.h>
#include <linux/err.h>
#include <linux/init.h>
#include <linux/interrupt.h>
#include <linux/kdebug.h>
#include <linux/module.h>
#include <linux/notifier.h>
#include <linux/of.h>
#include <linux/platform_device.h>
#include <linux/pm_runtime.h>
#include <linux/rculist.h>
#include <linux/sh_dma.h>
#include <linux/slab.h>
#include <linux/spinlock.h>

#include "../dmaengine.h"
#include "shdma.h"

/* DMA registers */
#define SAR     0x00    /* Source Address Register */
#define DAR     0x04    /* Destination Address Register */
#define TCR     0x08    /* Transfer Count Register */
#define CHCR    0x0C    /* Channel Control Register */
#define DMAOR   0x40    /* DMA Operation Register */

#define TEND    0x18 /* USB-DMAC */

#define SH_DMAE_DRV_NAME "sh-dma-engine"

/* Default MEMCPY transfer size = 2^2 = 4 bytes */
#define LOG2_DEFAULT_XFER_SIZE  2
#define SH_DMA_SLAVE_NUMBER 256
#define SH_DMA_TCR_MAX (16 * 1024 * 1024 - 1)

/*
 * Used for write-side mutual exclusion for the global device list,
 * read-side synchronization by way of RCU, and per-controller data.
 */
static DEFINE_SPINLOCK(sh_dmae_lock);
static LIST_HEAD(sh_dmae_devices);

/*
 * Different DMAC implementations provide different ways to clear DMA channels:
 * (1) none - no CHCLR registers are available
 * (2) one CHCLR register per channel - 0 has to be written to it to clear
 *     channel buffers
 * (3) one CHCLR per several channels - 1 has to be written to the bit,
 *     corresponding to the specific channel to reset it
 */
static void channel_clear(struct sh_dmae_chan *sh_dc)
{
        struct sh_dmae_device *shdev = to_sh_dev(sh_dc);
        const struct sh_dmae_channel *chan_pdata = shdev->pdata->channel +
                sh_dc->shdma_chan.id;
        u32 val = shdev->pdata->chclr_bitwise ? 1 << chan_pdata->chclr_bit : 0;

        __raw_writel(val, shdev->chan_reg + chan_pdata->chclr_offset);
}

static void sh_dmae_writel(struct sh_dmae_chan *sh_dc, u32 data, u32 reg)
{
        __raw_writel(data, sh_dc->base + reg);
}

static u32 sh_dmae_readl(struct sh_dmae_chan *sh_dc, u32 reg)
{
        return __raw_readl(sh_dc->base + reg);
}

static u16 dmaor_read(struct sh_dmae_device *shdev)
{
        void __iomem *addr = shdev->chan_reg + DMAOR;

        if (shdev->pdata->dmaor_is_32bit)
                return __raw_readl(addr);
        else
                return __raw_readw(addr);
}

static void dmaor_write(struct sh_dmae_device *shdev, u16 data)
{
        void __iomem *addr = shdev->chan_reg + DMAOR;

        if (shdev->pdata->dmaor_is_32bit)
                __raw_writel(data, addr);
        else
                __raw_writew(data, addr);
}

static void chcr_write(struct sh_dmae_chan *sh_dc, u32 data)
{
        struct sh_dmae_device *shdev = to_sh_dev(sh_dc);

        __raw_writel(data, sh_dc->base + shdev->chcr_offset);
}

static u32 chcr_read(struct sh_dmae_chan *sh_dc)
{
        struct sh_dmae_device *shdev = to_sh_dev(sh_dc);

        return __raw_readl(sh_dc->base + shdev->chcr_offset);
}

/*
 * Reset DMA controller
 *
 * SH7780 has two DMAOR register
 */
static void sh_dmae_ctl_stop(struct sh_dmae_device *shdev)
{
        unsigned short dmaor;
        unsigned long flags;

        spin_lock_irqsave(&sh_dmae_lock, flags);

        dmaor = dmaor_read(shdev);
        dmaor_write(shdev, dmaor & ~(DMAOR_NMIF | DMAOR_AE | DMAOR_DME));

        spin_unlock_irqrestore(&sh_dmae_lock, flags);
}

static int sh_dmae_rst(struct sh_dmae_device *shdev)
{
        unsigned short dmaor;
        unsigned long flags;

        spin_lock_irqsave(&sh_dmae_lock, flags);

        dmaor = dmaor_read(shdev) & ~(DMAOR_NMIF | DMAOR_AE | DMAOR_DME);

        if (shdev->pdata->chclr_present) {
                int i;
                for (i = 0; i < shdev->pdata->channel_num; i++) {
                        struct sh_dmae_chan *sh_chan = shdev->chan[i];
                        if (sh_chan)
                                channel_clear(sh_chan);
                }
        }

        dmaor_write(shdev, dmaor | shdev->pdata->dmaor_init);

        dmaor = dmaor_read(shdev);

        spin_unlock_irqrestore(&sh_dmae_lock, flags);

        if (dmaor & (DMAOR_AE | DMAOR_NMIF)) {
                dev_warn(shdev->shdma_dev.dma_dev.dev, "Can't initialize DMAOR.\n");
                return -EIO;
        }
        if (shdev->pdata->dmaor_init & ~dmaor)
                dev_warn(shdev->shdma_dev.dma_dev.dev,
                         "DMAOR=0x%x hasn't latched the initial value 0x%x.\n",
                         dmaor, shdev->pdata->dmaor_init);
        return 0;
}

static bool dmae_is_busy(struct sh_dmae_chan *sh_chan)
{
        u32 chcr = chcr_read(sh_chan);

        if ((chcr & (CHCR_DE | CHCR_TE)) == CHCR_DE)
                return true; /* working */

        return false; /* waiting */
}

static unsigned int calc_xmit_shift(struct sh_dmae_chan *sh_chan, u32 chcr)
{
        struct sh_dmae_device *shdev = to_sh_dev(sh_chan);
        const struct sh_dmae_pdata *pdata = shdev->pdata;
        int cnt = ((chcr & pdata->ts_low_mask) >> pdata->ts_low_shift) |
                ((chcr & pdata->ts_high_mask) >> pdata->ts_high_shift);

        if (cnt >= pdata->ts_shift_num)
                cnt = 0;

        return pdata->ts_shift[cnt];
}

static u32 log2size_to_chcr(struct sh_dmae_chan *sh_chan, int l2size)
{
        struct sh_dmae_device *shdev = to_sh_dev(sh_chan);
        const struct sh_dmae_pdata *pdata = shdev->pdata;
        int i;

        for (i = 0; i < pdata->ts_shift_num; i++)
                if (pdata->ts_shift[i] == l2size)
                        break;

        if (i == pdata->ts_shift_num)
                i = 0;

        return ((i << pdata->ts_low_shift) & pdata->ts_low_mask) |
                ((i << pdata->ts_high_shift) & pdata->ts_high_mask);
}

static void dmae_set_reg(struct sh_dmae_chan *sh_chan, struct sh_dmae_regs *hw)
{
        sh_dmae_writel(sh_chan, hw->sar, SAR);
        sh_dmae_writel(sh_chan, hw->dar, DAR);
        sh_dmae_writel(sh_chan, hw->tcr >> sh_chan->xmit_shift, TCR);
}

static void dmae_start(struct sh_dmae_chan *sh_chan)
{
        struct sh_dmae_device *shdev = to_sh_dev(sh_chan);
        u32 chcr = chcr_read(sh_chan);

        if (shdev->pdata->needs_tend_set)
                sh_dmae_writel(sh_chan, 0xFFFFFFFF, TEND);

        chcr |= CHCR_DE | shdev->chcr_ie_bit;
        chcr_write(sh_chan, chcr & ~CHCR_TE);
}

static void dmae_init(struct sh_dmae_chan *sh_chan)
{
        /*
         * Default configuration for dual address memory-memory transfer.
         */
        u32 chcr = DM_INC | SM_INC | RS_AUTO | log2size_to_chcr(sh_chan,
                                                   LOG2_DEFAULT_XFER_SIZE);
        sh_chan->xmit_shift = calc_xmit_shift(sh_chan, chcr);
        chcr_write(sh_chan, chcr);
}

static int dmae_set_chcr(struct sh_dmae_chan *sh_chan, u32 val)
{
        /* If DMA is active, cannot set CHCR. TODO: remove this superfluous check */
        if (dmae_is_busy(sh_chan))
                return -EBUSY;

        sh_chan->xmit_shift = calc_xmit_shift(sh_chan, val);
        chcr_write(sh_chan, val);

        return 0;
}

static int dmae_set_dmars(struct sh_dmae_chan *sh_chan, u16 val)
{
        struct sh_dmae_device *shdev = to_sh_dev(sh_chan);
        const struct sh_dmae_pdata *pdata = shdev->pdata;
        const struct sh_dmae_channel *chan_pdata = &pdata->channel[sh_chan->shdma_chan.id];
        void __iomem *addr = shdev->dmars;
        unsigned int shift = chan_pdata->dmars_bit;

        if (dmae_is_busy(sh_chan))
                return -EBUSY;

        if (pdata->no_dmars)
                return 0;

        /* in the case of a missing DMARS resource use first memory window */
        if (!addr)
                addr = shdev->chan_reg;
        addr += chan_pdata->dmars;

        __raw_writew((__raw_readw(addr) & (0xff00 >> shift)) | (val << shift),
                     addr);

        return 0;
}

static void sh_dmae_start_xfer(struct shdma_chan *schan,
                               struct shdma_desc *sdesc)
{
        struct sh_dmae_chan *sh_chan = container_of(schan, struct sh_dmae_chan,
                                                    shdma_chan);
        struct sh_dmae_desc *sh_desc = container_of(sdesc,
                                        struct sh_dmae_desc, shdma_desc);
        dev_dbg(sh_chan->shdma_chan.dev, "Queue #%d to %d: %u@%x -> %x\n",
                sdesc->async_tx.cookie, sh_chan->shdma_chan.id,
                sh_desc->hw.tcr, sh_desc->hw.sar, sh_desc->hw.dar);
        /* Get the ld start address from ld_queue */
        dmae_set_reg(sh_chan, &sh_desc->hw);
        dmae_start(sh_chan);
}

static bool sh_dmae_channel_busy(struct shdma_chan *schan)
{
        struct sh_dmae_chan *sh_chan = container_of(schan, struct sh_dmae_chan,
                                                    shdma_chan);
        return dmae_is_busy(sh_chan);
}

static int sh_dmae_setup_xfer(struct shdma_chan *schan, int slave_id)
{
        struct sh_dmae_chan *sh_chan = container_of(schan, struct sh_dmae_chan,
                                                    shdma_chan);

        int ret = 0;
        if (slave_id >= 0) {
                const struct sh_dmae_slave_config *cfg =
                        sh_chan->config;

                ret = dmae_set_dmars(sh_chan, cfg->mid_rid);
                if (ret < 0)
                        goto END;

                ret = dmae_set_chcr(sh_chan, cfg->chcr);
                if (ret < 0)
                        goto END;

        } else {
                dmae_init(sh_chan);
        }

END:
        return ret;
}

/*
 * Find a slave channel configuration from the controller list by either a slave
 * ID in the non-DT case, or by a MID/RID value in the DT case
 */
static const struct sh_dmae_slave_config *dmae_find_slave(
        struct sh_dmae_chan *sh_chan, int match)
{
        struct sh_dmae_device *shdev = to_sh_dev(sh_chan);
        const struct sh_dmae_pdata *pdata = shdev->pdata;
        const struct sh_dmae_slave_config *cfg;
        int i;

        if (!sh_chan->shdma_chan.dev->of_node) {
                if (match >= SH_DMA_SLAVE_NUMBER)
                        return NULL;

                for (i = 0, cfg = pdata->slave; i < pdata->slave_num; i++, cfg++)
                        if (cfg->slave_id == match)
                                return cfg;
        } else {
                for (i = 0, cfg = pdata->slave; i < pdata->slave_num; i++, cfg++)
                        if (cfg->mid_rid == match) {
                                sh_chan->shdma_chan.slave_id = i;
                                return cfg;
                        }
        }

        return NULL;
}

static int sh_dmae_set_slave(struct shdma_chan *schan,
                             int slave_id, dma_addr_t slave_addr, bool try)
{
        struct sh_dmae_chan *sh_chan = container_of(schan, struct sh_dmae_chan,
                                                    shdma_chan);
        const struct sh_dmae_slave_config *cfg = dmae_find_slave(sh_chan, slave_id);
        if (!cfg)
                return -ENXIO;

        if (!try) {
                sh_chan->config = cfg;
                sh_chan->slave_addr = slave_addr ? : cfg->addr;
        }

        return 0;
}

static void dmae_halt(struct sh_dmae_chan *sh_chan)
{
        struct sh_dmae_device *shdev = to_sh_dev(sh_chan);
        u32 chcr = chcr_read(sh_chan);

        chcr &= ~(CHCR_DE | CHCR_TE | shdev->chcr_ie_bit);
        chcr_write(sh_chan, chcr);
}

static int sh_dmae_desc_setup(struct shdma_chan *schan,
                              struct shdma_desc *sdesc,
                              dma_addr_t src, dma_addr_t dst, size_t *len)
{
        struct sh_dmae_desc *sh_desc = container_of(sdesc,
                                        struct sh_dmae_desc, shdma_desc);

        if (*len > schan->max_xfer_len)
                *len = schan->max_xfer_len;

        sh_desc->hw.sar = src;
        sh_desc->hw.dar = dst;
        sh_desc->hw.tcr = *len;

        return 0;
}

static void sh_dmae_halt(struct shdma_chan *schan)
{
        struct sh_dmae_chan *sh_chan = container_of(schan, struct sh_dmae_chan,
                                                    shdma_chan);
        dmae_halt(sh_chan);
}

static bool sh_dmae_chan_irq(struct shdma_chan *schan, int irq)
{
        struct sh_dmae_chan *sh_chan = container_of(schan, struct sh_dmae_chan,
                                                    shdma_chan);

        if (!(chcr_read(sh_chan) & CHCR_TE))
                return false;

        /* DMA stop */
        dmae_halt(sh_chan);

        return true;
}

static size_t sh_dmae_get_partial(struct shdma_chan *schan,
                                  struct shdma_desc *sdesc)
{
        struct sh_dmae_chan *sh_chan = container_of(schan, struct sh_dmae_chan,
                                                    shdma_chan);
        struct sh_dmae_desc *sh_desc = container_of(sdesc,
                                        struct sh_dmae_desc, shdma_desc);
        return sh_desc->hw.tcr -
                (sh_dmae_readl(sh_chan, TCR) << sh_chan->xmit_shift);
}

/* Called from error IRQ or NMI */
static bool sh_dmae_reset(struct sh_dmae_device *shdev)
{
        bool ret;

        /* halt the dma controller */
        sh_dmae_ctl_stop(shdev);

        /* We cannot detect, which channel caused the error, have to reset all */
        ret = shdma_reset(&shdev->shdma_dev);

        sh_dmae_rst(shdev);

        return ret;
}

static irqreturn_t sh_dmae_err(int irq, void *data)
{
        struct sh_dmae_device *shdev = data;

        if (!(dmaor_read(shdev) & DMAOR_AE))
                return IRQ_NONE;

        sh_dmae_reset(shdev);
        return IRQ_HANDLED;
}

static bool sh_dmae_desc_completed(struct shdma_chan *schan,
                                   struct shdma_desc *sdesc)
{
        struct sh_dmae_chan *sh_chan = container_of(schan,
                                        struct sh_dmae_chan, shdma_chan);
        struct sh_dmae_desc *sh_desc = container_of(sdesc,
                                        struct sh_dmae_desc, shdma_desc);
        u32 sar_buf = sh_dmae_readl(sh_chan, SAR);
        u32 dar_buf = sh_dmae_readl(sh_chan, DAR);

        return  (sdesc->direction == DMA_DEV_TO_MEM &&
                 (sh_desc->hw.dar + sh_desc->hw.tcr) == dar_buf) ||
                (sdesc->direction != DMA_DEV_TO_MEM &&
                 (sh_desc->hw.sar + sh_desc->hw.tcr) == sar_buf);
}

static bool sh_dmae_nmi_notify(struct sh_dmae_device *shdev)
{
        /* Fast path out if NMIF is not asserted for this controller */
        if ((dmaor_read(shdev) & DMAOR_NMIF) == 0)
                return false;

        return sh_dmae_reset(shdev);
}

static int sh_dmae_nmi_handler(struct notifier_block *self,
                               unsigned long cmd, void *data)
{
        struct sh_dmae_device *shdev;
        int ret = NOTIFY_DONE;
        bool triggered;

        /*
         * Only concern ourselves with NMI events.
         *
         * Normally we would check the die chain value, but as this needs
         * to be architecture independent, check for NMI context instead.
         */
        if (!in_nmi())
                return NOTIFY_DONE;

        rcu_read_lock();
        list_for_each_entry_rcu(shdev, &sh_dmae_devices, node) {
                /*
                 * Only stop if one of the controllers has NMIF asserted,
                 * we do not want to interfere with regular address error
                 * handling or NMI events that don't concern the DMACs.
                 */
                triggered = sh_dmae_nmi_notify(shdev);
                if (triggered == true)
                        ret = NOTIFY_OK;
        }
        rcu_read_unlock();

        return ret;
}

static struct notifier_block sh_dmae_nmi_notifier __read_mostly = {
        .notifier_call  = sh_dmae_nmi_handler,

        /* Run before NMI debug handler and KGDB */
        .priority       = 1,
};

static int sh_dmae_chan_probe(struct sh_dmae_device *shdev, int id,
                                        int irq, unsigned long flags)
{
        const struct sh_dmae_channel *chan_pdata = &shdev->pdata->channel[id];
        struct shdma_dev *sdev = &shdev->shdma_dev;
        struct platform_device *pdev = to_platform_device(sdev->dma_dev.dev);
        struct sh_dmae_chan *sh_chan;
        struct shdma_chan *schan;
        int err;

        sh_chan = devm_kzalloc(sdev->dma_dev.dev, sizeof(struct sh_dmae_chan),
                               GFP_KERNEL);
        if (!sh_chan)
                return -ENOMEM;

        schan = &sh_chan->shdma_chan;
        schan->max_xfer_len = SH_DMA_TCR_MAX + 1;

        shdma_chan_probe(sdev, schan, id);

        sh_chan->base = shdev->chan_reg + chan_pdata->offset;

        /* set up channel irq */
        if (pdev->id >= 0)
                snprintf(sh_chan->dev_id, sizeof(sh_chan->dev_id),
                         "sh-dmae%d.%d", pdev->id, id);
        else
                snprintf(sh_chan->dev_id, sizeof(sh_chan->dev_id),
                         "sh-dma%d", id);

        err = shdma_request_irq(schan, irq, flags, sh_chan->dev_id);
        if (err) {
                dev_err(sdev->dma_dev.dev,
                        "DMA channel %d request_irq error %d\n",
                        id, err);
                goto err_no_irq;
        }

        shdev->chan[id] = sh_chan;
        return 0;

err_no_irq:
        /* remove from dmaengine device node */
        shdma_chan_remove(schan);
        return err;
}

static void sh_dmae_chan_remove(struct sh_dmae_device *shdev)
{
        struct shdma_chan *schan;
        int i;

        shdma_for_each_chan(schan, &shdev->shdma_dev, i) {
                BUG_ON(!schan);

                shdma_chan_remove(schan);
        }
}

#ifdef CONFIG_PM
static int sh_dmae_runtime_suspend(struct device *dev)
{
        struct sh_dmae_device *shdev = dev_get_drvdata(dev);

        sh_dmae_ctl_stop(shdev);
        return 0;
}

static int sh_dmae_runtime_resume(struct device *dev)
{
        struct sh_dmae_device *shdev = dev_get_drvdata(dev);

        return sh_dmae_rst(shdev);
}
#endif

#ifdef CONFIG_PM_SLEEP
static int sh_dmae_suspend(struct device *dev)
{
        struct sh_dmae_device *shdev = dev_get_drvdata(dev);

        sh_dmae_ctl_stop(shdev);
        return 0;
}

static int sh_dmae_resume(struct device *dev)
{
        struct sh_dmae_device *shdev = dev_get_drvdata(dev);
        int i, ret;

        ret = sh_dmae_rst(shdev);
        if (ret < 0)
                dev_err(dev, "Failed to reset!\n");

        for (i = 0; i < shdev->pdata->channel_num; i++) {
                struct sh_dmae_chan *sh_chan = shdev->chan[i];

                if (!sh_chan->shdma_chan.desc_num)
                        continue;

                if (sh_chan->shdma_chan.slave_id >= 0) {
                        const struct sh_dmae_slave_config *cfg = sh_chan->config;
                        dmae_set_dmars(sh_chan, cfg->mid_rid);
                        dmae_set_chcr(sh_chan, cfg->chcr);
                } else {
                        dmae_init(sh_chan);
                }
        }

        return 0;
}
#endif

static const struct dev_pm_ops sh_dmae_pm = {
        SET_SYSTEM_SLEEP_PM_OPS(sh_dmae_suspend, sh_dmae_resume)
        SET_RUNTIME_PM_OPS(sh_dmae_runtime_suspend, sh_dmae_runtime_resume,
                           NULL)
};

static dma_addr_t sh_dmae_slave_addr(struct shdma_chan *schan)
{
        struct sh_dmae_chan *sh_chan = container_of(schan,
                                        struct sh_dmae_chan, shdma_chan);

        /*
         * Implicit BUG_ON(!sh_chan->config)
         * This is an exclusive slave DMA operation, may only be called after a
         * successful slave configuration.
         */
        return sh_chan->slave_addr;
}

static struct shdma_desc *sh_dmae_embedded_desc(void *buf, int i)
{
        return &((struct sh_dmae_desc *)buf)[i].shdma_desc;
}

static const struct shdma_ops sh_dmae_shdma_ops = {
        .desc_completed = sh_dmae_desc_completed,
        .halt_channel = sh_dmae_halt,
        .channel_busy = sh_dmae_channel_busy,
        .slave_addr = sh_dmae_slave_addr,
        .desc_setup = sh_dmae_desc_setup,
        .set_slave = sh_dmae_set_slave,
        .setup_xfer = sh_dmae_setup_xfer,
        .start_xfer = sh_dmae_start_xfer,
        .embedded_desc = sh_dmae_embedded_desc,
        .chan_irq = sh_dmae_chan_irq,
        .get_partial = sh_dmae_get_partial,
};

static int sh_dmae_probe(struct platform_device *pdev)
{
        const enum dma_slave_buswidth widths =
                DMA_SLAVE_BUSWIDTH_1_BYTE   | DMA_SLAVE_BUSWIDTH_2_BYTES |
                DMA_SLAVE_BUSWIDTH_4_BYTES  | DMA_SLAVE_BUSWIDTH_8_BYTES |
                DMA_SLAVE_BUSWIDTH_16_BYTES | DMA_SLAVE_BUSWIDTH_32_BYTES;
        const struct sh_dmae_pdata *pdata;
        unsigned long chan_flag[SH_DMAE_MAX_CHANNELS] = {};
        int chan_irq[SH_DMAE_MAX_CHANNELS];
        unsigned long irqflags = 0;
        int err, errirq, i, irq_cnt = 0, irqres = 0, irq_cap = 0;
        struct sh_dmae_device *shdev;
        struct dma_device *dma_dev;
        struct resource *dmars, *errirq_res, *chanirq_res;

        if (pdev->dev.of_node)
                pdata = of_device_get_match_data(&pdev->dev);
        else
                pdata = dev_get_platdata(&pdev->dev);

        /* get platform data */
        if (!pdata || !pdata->channel_num)
                return -ENODEV;

        /* DMARS area is optional */
        dmars = platform_get_resource(pdev, IORESOURCE_MEM, 1);
        /*
         * IRQ resources:
         * 1. there always must be at least one IRQ IO-resource. On SH4 it is
         *    the error IRQ, in which case it is the only IRQ in this resource:
         *    start == end. If it is the only IRQ resource, all channels also
         *    use the same IRQ.
         * 2. DMA channel IRQ resources can be specified one per resource or in
         *    ranges (start != end)
         * 3. iff all events (channels and, optionally, error) on this
         *    controller use the same IRQ, only one IRQ resource can be
         *    specified, otherwise there must be one IRQ per channel, even if
         *    some of them are equal
         * 4. if all IRQs on this controller are equal or if some specific IRQs
         *    specify IORESOURCE_IRQ_SHAREABLE in their resources, they will be
         *    requested with the IRQF_SHARED flag
         */
        errirq_res = platform_get_resource(pdev, IORESOURCE_IRQ, 0);
        if (!errirq_res)
                return -ENODEV;

        shdev = devm_kzalloc(&pdev->dev, sizeof(struct sh_dmae_device),
                             GFP_KERNEL);
        if (!shdev)
                return -ENOMEM;

        dma_dev = &shdev->shdma_dev.dma_dev;

        shdev->chan_reg = devm_platform_ioremap_resource(pdev, 0);
        if (IS_ERR(shdev->chan_reg))
                return PTR_ERR(shdev->chan_reg);
        if (dmars) {
                shdev->dmars = devm_ioremap_resource(&pdev->dev, dmars);
                if (IS_ERR(shdev->dmars))
                        return PTR_ERR(shdev->dmars);
        }

        dma_dev->src_addr_widths = widths;
        dma_dev->dst_addr_widths = widths;
        dma_dev->directions = BIT(DMA_MEM_TO_DEV) | BIT(DMA_DEV_TO_MEM);
        dma_dev->residue_granularity = DMA_RESIDUE_GRANULARITY_DESCRIPTOR;

        if (!pdata->slave_only)
                dma_cap_set(DMA_MEMCPY, dma_dev->cap_mask);
        if (pdata->slave && pdata->slave_num)
                dma_cap_set(DMA_SLAVE, dma_dev->cap_mask);

        /* Default transfer size of 32 bytes requires 32-byte alignment */
        dma_dev->copy_align = LOG2_DEFAULT_XFER_SIZE;

        shdev->shdma_dev.ops = &sh_dmae_shdma_ops;
        shdev->shdma_dev.desc_size = sizeof(struct sh_dmae_desc);
        err = shdma_init(&pdev->dev, &shdev->shdma_dev,
                              pdata->channel_num);
        if (err < 0)
                goto eshdma;

        /* platform data */
        shdev->pdata = pdata;

        if (pdata->chcr_offset)
                shdev->chcr_offset = pdata->chcr_offset;
        else
                shdev->chcr_offset = CHCR;

        if (pdata->chcr_ie_bit)
                shdev->chcr_ie_bit = pdata->chcr_ie_bit;
        else
                shdev->chcr_ie_bit = CHCR_IE;

        platform_set_drvdata(pdev, shdev);

        pm_runtime_enable(&pdev->dev);
        err = pm_runtime_get_sync(&pdev->dev);
        if (err < 0)
                dev_err(&pdev->dev, "%s(): GET = %d\n", __func__, err);

        spin_lock_irq(&sh_dmae_lock);
        list_add_tail_rcu(&shdev->node, &sh_dmae_devices);
        spin_unlock_irq(&sh_dmae_lock);

        /* reset dma controller - only needed as a test */
        err = sh_dmae_rst(shdev);
        if (err)
                goto rst_err;

        if (IS_ENABLED(CONFIG_CPU_SH4) || IS_ENABLED(CONFIG_ARCH_RENESAS)) {
                chanirq_res = platform_get_resource(pdev, IORESOURCE_IRQ, 1);

                if (!chanirq_res)
                        chanirq_res = errirq_res;
                else
                        irqres++;

                if (chanirq_res == errirq_res ||
                    (errirq_res->flags & IORESOURCE_BITS) == IORESOURCE_IRQ_SHAREABLE)
                        irqflags = IRQF_SHARED;

                errirq = errirq_res->start;

                err = devm_request_irq(&pdev->dev, errirq, sh_dmae_err,
                                       irqflags, "DMAC Address Error", shdev);
                if (err) {
                        dev_err(&pdev->dev,
                                "DMA failed requesting irq #%d, error %d\n",
                                errirq, err);
                        goto eirq_err;
                }
        } else {
                chanirq_res = errirq_res;
        }

        if (chanirq_res->start == chanirq_res->end &&
            !platform_get_resource(pdev, IORESOURCE_IRQ, 1)) {
                /* Special case - all multiplexed */
                for (; irq_cnt < pdata->channel_num; irq_cnt++) {
                        if (irq_cnt < SH_DMAE_MAX_CHANNELS) {
                                chan_irq[irq_cnt] = chanirq_res->start;
                                chan_flag[irq_cnt] = IRQF_SHARED;
                        } else {
                                irq_cap = 1;
                                break;
                        }
                }
        } else {
                do {
                        for (i = chanirq_res->start; i <= chanirq_res->end; i++) {
                                if (irq_cnt >= SH_DMAE_MAX_CHANNELS) {
                                        irq_cap = 1;
                                        break;
                                }

                                if ((errirq_res->flags & IORESOURCE_BITS) ==
                                    IORESOURCE_IRQ_SHAREABLE)
                                        chan_flag[irq_cnt] = IRQF_SHARED;
                                else
                                        chan_flag[irq_cnt] = 0;
                                dev_dbg(&pdev->dev,
                                        "Found IRQ %d for channel %d\n",
                                        i, irq_cnt);
                                chan_irq[irq_cnt++] = i;
                        }

                        if (irq_cnt >= SH_DMAE_MAX_CHANNELS)
                                break;

                        chanirq_res = platform_get_resource(pdev,
                                                IORESOURCE_IRQ, ++irqres);
                } while (irq_cnt < pdata->channel_num && chanirq_res);
        }

        /* Create DMA Channel */
        for (i = 0; i < irq_cnt; i++) {
                err = sh_dmae_chan_probe(shdev, i, chan_irq[i], chan_flag[i]);
                if (err)
                        goto chan_probe_err;
        }

        if (irq_cap)
                dev_notice(&pdev->dev, "Attempting to register %d DMA "
                           "channels when a maximum of %d are supported.\n",
                           pdata->channel_num, SH_DMAE_MAX_CHANNELS);

        pm_runtime_put(&pdev->dev);

        err = dma_async_device_register(&shdev->shdma_dev.dma_dev);
        if (err < 0)
                goto edmadevreg;

        return err;

edmadevreg:
        pm_runtime_get(&pdev->dev);

chan_probe_err:
        sh_dmae_chan_remove(shdev);

eirq_err:
rst_err:
        spin_lock_irq(&sh_dmae_lock);
        list_del_rcu(&shdev->node);
        spin_unlock_irq(&sh_dmae_lock);

        pm_runtime_put(&pdev->dev);
        pm_runtime_disable(&pdev->dev);

        shdma_cleanup(&shdev->shdma_dev);
eshdma:
        synchronize_rcu();

        return err;
}

static void sh_dmae_remove(struct platform_device *pdev)
{
        struct sh_dmae_device *shdev = platform_get_drvdata(pdev);
        struct dma_device *dma_dev = &shdev->shdma_dev.dma_dev;

        dma_async_device_unregister(dma_dev);

        spin_lock_irq(&sh_dmae_lock);
        list_del_rcu(&shdev->node);
        spin_unlock_irq(&sh_dmae_lock);

        pm_runtime_disable(&pdev->dev);

        sh_dmae_chan_remove(shdev);
        shdma_cleanup(&shdev->shdma_dev);

        synchronize_rcu();
}

static struct platform_driver sh_dmae_driver = {
        .driver         = {
                .pm     = &sh_dmae_pm,
                .name   = SH_DMAE_DRV_NAME,
        },
        .remove         = sh_dmae_remove,
};

static int __init sh_dmae_init(void)
{
        /* Wire up NMI handling */
        int err = register_die_notifier(&sh_dmae_nmi_notifier);
        if (err)
                return err;

        return platform_driver_probe(&sh_dmae_driver, sh_dmae_probe);
}
module_init(sh_dmae_init);

static void __exit sh_dmae_exit(void)
{
        platform_driver_unregister(&sh_dmae_driver);

        unregister_die_notifier(&sh_dmae_nmi_notifier);
}
module_exit(sh_dmae_exit);

MODULE_AUTHOR("Nobuhiro Iwamatsu <iwamatsu.nobuhiro@renesas.com>");
MODULE_DESCRIPTION("Renesas SH DMA Engine driver");
MODULE_LICENSE("GPL");
MODULE_ALIAS("platform:" SH_DMAE_DRV_NAME);