// SPDX-License-Identifier: GPL-2.0-only
/*
 * Copyright (c) 2013-2014, The Linux Foundation. All rights reserved.
 */
/*
 * QCOM BAM DMA engine driver
 *
 * QCOM BAM DMA blocks are distributed amongst a number of the on-chip
 * peripherals on the MSM 8x74.  The configuration of the channels are dependent
 * on the way they are hard wired to that specific peripheral.  The peripheral
 * device tree entries specify the configuration of each channel.
 *
 * The DMA controller requires the use of external memory for storage of the
 * hardware descriptors for each channel.  The descriptor FIFO is accessed as a
 * circular buffer and operations are managed according to the offset within the
 * FIFO.  After pipe/channel reset, all of the pipe registers and internal state
 * are back to defaults.
 *
 * During DMA operations, we write descriptors to the FIFO, being careful to
 * handle wrapping and then write the last FIFO offset to that channel's
 * P_EVNT_REG register to kick off the transaction.  The P_SW_OFSTS register
 * indicates the current FIFO offset that is being processed, so there is some
 * indication of where the hardware is currently working.
 */

#include <linux/kernel.h>
#include <linux/io.h>
#include <linux/init.h>
#include <linux/slab.h>
#include <linux/module.h>
#include <linux/interrupt.h>
#include <linux/dma-mapping.h>
#include <linux/scatterlist.h>
#include <linux/device.h>
#include <linux/platform_device.h>
#include <linux/of.h>
#include <linux/of_address.h>
#include <linux/of_irq.h>
#include <linux/of_dma.h>
#include <linux/circ_buf.h>
#include <linux/clk.h>
#include <linux/dmaengine.h>
#include <linux/pm_runtime.h>

#include "../dmaengine.h"
#include "../virt-dma.h"

struct bam_desc_hw {
        __le32 addr;            /* Buffer physical address */
        __le16 size;            /* Buffer size in bytes */
        __le16 flags;
};

#define BAM_DMA_AUTOSUSPEND_DELAY 100

#define DESC_FLAG_INT BIT(15)
#define DESC_FLAG_EOT BIT(14)
#define DESC_FLAG_EOB BIT(13)
#define DESC_FLAG_NWD BIT(12)
#define DESC_FLAG_CMD BIT(11)

struct bam_async_desc {
        struct virt_dma_desc vd;

        u32 num_desc;
        u32 xfer_len;

        /* transaction flags, EOT|EOB|NWD */
        u16 flags;

        struct bam_desc_hw *curr_desc;

        /* list node for the desc in the bam_chan list of descriptors */
        struct list_head desc_node;
        enum dma_transfer_direction dir;
        size_t length;
        struct bam_desc_hw desc[];
};

enum bam_reg {
        BAM_CTRL,
        BAM_REVISION,
        BAM_NUM_PIPES,
        BAM_DESC_CNT_TRSHLD,
        BAM_IRQ_SRCS,
        BAM_IRQ_SRCS_MSK,
        BAM_IRQ_SRCS_UNMASKED,
        BAM_IRQ_STTS,
        BAM_IRQ_CLR,
        BAM_IRQ_EN,
        BAM_CNFG_BITS,
        BAM_IRQ_SRCS_EE,
        BAM_IRQ_SRCS_MSK_EE,
        BAM_P_CTRL,
        BAM_P_RST,
        BAM_P_HALT,
        BAM_P_IRQ_STTS,
        BAM_P_IRQ_CLR,
        BAM_P_IRQ_EN,
        BAM_P_EVNT_DEST_ADDR,
        BAM_P_EVNT_REG,
        BAM_P_SW_OFSTS,
        BAM_P_DATA_FIFO_ADDR,
        BAM_P_DESC_FIFO_ADDR,
        BAM_P_EVNT_GEN_TRSHLD,
        BAM_P_FIFO_SIZES,
};

struct reg_offset_data {
        u32 base_offset;
        unsigned int pipe_mult, evnt_mult, ee_mult;
};

static const struct reg_offset_data bam_v1_3_reg_info[] = {
        [BAM_CTRL]              = { 0x0F80, 0x00, 0x00, 0x00 },
        [BAM_REVISION]          = { 0x0F84, 0x00, 0x00, 0x00 },
        [BAM_NUM_PIPES]         = { 0x0FBC, 0x00, 0x00, 0x00 },
        [BAM_DESC_CNT_TRSHLD]   = { 0x0F88, 0x00, 0x00, 0x00 },
        [BAM_IRQ_SRCS]          = { 0x0F8C, 0x00, 0x00, 0x00 },
        [BAM_IRQ_SRCS_MSK]      = { 0x0F90, 0x00, 0x00, 0x00 },
        [BAM_IRQ_SRCS_UNMASKED] = { 0x0FB0, 0x00, 0x00, 0x00 },
        [BAM_IRQ_STTS]          = { 0x0F94, 0x00, 0x00, 0x00 },
        [BAM_IRQ_CLR]           = { 0x0F98, 0x00, 0x00, 0x00 },
        [BAM_IRQ_EN]            = { 0x0F9C, 0x00, 0x00, 0x00 },
        [BAM_CNFG_BITS]         = { 0x0FFC, 0x00, 0x00, 0x00 },
        [BAM_IRQ_SRCS_EE]       = { 0x1800, 0x00, 0x00, 0x80 },
        [BAM_IRQ_SRCS_MSK_EE]   = { 0x1804, 0x00, 0x00, 0x80 },
        [BAM_P_CTRL]            = { 0x0000, 0x80, 0x00, 0x00 },
        [BAM_P_RST]             = { 0x0004, 0x80, 0x00, 0x00 },
        [BAM_P_HALT]            = { 0x0008, 0x80, 0x00, 0x00 },
        [BAM_P_IRQ_STTS]        = { 0x0010, 0x80, 0x00, 0x00 },
        [BAM_P_IRQ_CLR]         = { 0x0014, 0x80, 0x00, 0x00 },
        [BAM_P_IRQ_EN]          = { 0x0018, 0x80, 0x00, 0x00 },
        [BAM_P_EVNT_DEST_ADDR]  = { 0x102C, 0x00, 0x40, 0x00 },
        [BAM_P_EVNT_REG]        = { 0x1018, 0x00, 0x40, 0x00 },
        [BAM_P_SW_OFSTS]        = { 0x1000, 0x00, 0x40, 0x00 },
        [BAM_P_DATA_FIFO_ADDR]  = { 0x1024, 0x00, 0x40, 0x00 },
        [BAM_P_DESC_FIFO_ADDR]  = { 0x101C, 0x00, 0x40, 0x00 },
        [BAM_P_EVNT_GEN_TRSHLD] = { 0x1028, 0x00, 0x40, 0x00 },
        [BAM_P_FIFO_SIZES]      = { 0x1020, 0x00, 0x40, 0x00 },
};

static const struct reg_offset_data bam_v1_4_reg_info[] = {
        [BAM_CTRL]              = { 0x0000, 0x00, 0x00, 0x00 },
        [BAM_REVISION]          = { 0x0004, 0x00, 0x00, 0x00 },
        [BAM_NUM_PIPES]         = { 0x003C, 0x00, 0x00, 0x00 },
        [BAM_DESC_CNT_TRSHLD]   = { 0x0008, 0x00, 0x00, 0x00 },
        [BAM_IRQ_SRCS]          = { 0x000C, 0x00, 0x00, 0x00 },
        [BAM_IRQ_SRCS_MSK]      = { 0x0010, 0x00, 0x00, 0x00 },
        [BAM_IRQ_SRCS_UNMASKED] = { 0x0030, 0x00, 0x00, 0x00 },
        [BAM_IRQ_STTS]          = { 0x0014, 0x00, 0x00, 0x00 },
        [BAM_IRQ_CLR]           = { 0x0018, 0x00, 0x00, 0x00 },
        [BAM_IRQ_EN]            = { 0x001C, 0x00, 0x00, 0x00 },
        [BAM_CNFG_BITS]         = { 0x007C, 0x00, 0x00, 0x00 },
        [BAM_IRQ_SRCS_EE]       = { 0x0800, 0x00, 0x00, 0x80 },
        [BAM_IRQ_SRCS_MSK_EE]   = { 0x0804, 0x00, 0x00, 0x80 },
        [BAM_P_CTRL]            = { 0x1000, 0x1000, 0x00, 0x00 },
        [BAM_P_RST]             = { 0x1004, 0x1000, 0x00, 0x00 },
        [BAM_P_HALT]            = { 0x1008, 0x1000, 0x00, 0x00 },
        [BAM_P_IRQ_STTS]        = { 0x1010, 0x1000, 0x00, 0x00 },
        [BAM_P_IRQ_CLR]         = { 0x1014, 0x1000, 0x00, 0x00 },
        [BAM_P_IRQ_EN]          = { 0x1018, 0x1000, 0x00, 0x00 },
        [BAM_P_EVNT_DEST_ADDR]  = { 0x182C, 0x00, 0x1000, 0x00 },
        [BAM_P_EVNT_REG]        = { 0x1818, 0x00, 0x1000, 0x00 },
        [BAM_P_SW_OFSTS]        = { 0x1800, 0x00, 0x1000, 0x00 },
        [BAM_P_DATA_FIFO_ADDR]  = { 0x1824, 0x00, 0x1000, 0x00 },
        [BAM_P_DESC_FIFO_ADDR]  = { 0x181C, 0x00, 0x1000, 0x00 },
        [BAM_P_EVNT_GEN_TRSHLD] = { 0x1828, 0x00, 0x1000, 0x00 },
        [BAM_P_FIFO_SIZES]      = { 0x1820, 0x00, 0x1000, 0x00 },
};

static const struct reg_offset_data bam_v1_7_reg_info[] = {
        [BAM_CTRL]              = { 0x00000, 0x00, 0x00, 0x00 },
        [BAM_REVISION]          = { 0x01000, 0x00, 0x00, 0x00 },
        [BAM_NUM_PIPES]         = { 0x01008, 0x00, 0x00, 0x00 },
        [BAM_DESC_CNT_TRSHLD]   = { 0x00008, 0x00, 0x00, 0x00 },
        [BAM_IRQ_SRCS]          = { 0x03010, 0x00, 0x00, 0x00 },
        [BAM_IRQ_SRCS_MSK]      = { 0x03014, 0x00, 0x00, 0x00 },
        [BAM_IRQ_SRCS_UNMASKED] = { 0x03018, 0x00, 0x00, 0x00 },
        [BAM_IRQ_STTS]          = { 0x00014, 0x00, 0x00, 0x00 },
        [BAM_IRQ_CLR]           = { 0x00018, 0x00, 0x00, 0x00 },
        [BAM_IRQ_EN]            = { 0x0001C, 0x00, 0x00, 0x00 },
        [BAM_CNFG_BITS]         = { 0x0007C, 0x00, 0x00, 0x00 },
        [BAM_IRQ_SRCS_EE]       = { 0x03000, 0x00, 0x00, 0x1000 },
        [BAM_IRQ_SRCS_MSK_EE]   = { 0x03004, 0x00, 0x00, 0x1000 },
        [BAM_P_CTRL]            = { 0x13000, 0x1000, 0x00, 0x00 },
        [BAM_P_RST]             = { 0x13004, 0x1000, 0x00, 0x00 },
        [BAM_P_HALT]            = { 0x13008, 0x1000, 0x00, 0x00 },
        [BAM_P_IRQ_STTS]        = { 0x13010, 0x1000, 0x00, 0x00 },
        [BAM_P_IRQ_CLR]         = { 0x13014, 0x1000, 0x00, 0x00 },
        [BAM_P_IRQ_EN]          = { 0x13018, 0x1000, 0x00, 0x00 },
        [BAM_P_EVNT_DEST_ADDR]  = { 0x1382C, 0x00, 0x1000, 0x00 },
        [BAM_P_EVNT_REG]        = { 0x13818, 0x00, 0x1000, 0x00 },
        [BAM_P_SW_OFSTS]        = { 0x13800, 0x00, 0x1000, 0x00 },
        [BAM_P_DATA_FIFO_ADDR]  = { 0x13824, 0x00, 0x1000, 0x00 },
        [BAM_P_DESC_FIFO_ADDR]  = { 0x1381C, 0x00, 0x1000, 0x00 },
        [BAM_P_EVNT_GEN_TRSHLD] = { 0x13828, 0x00, 0x1000, 0x00 },
        [BAM_P_FIFO_SIZES]      = { 0x13820, 0x00, 0x1000, 0x00 },
};

/* BAM CTRL */
#define BAM_SW_RST                      BIT(0)
#define BAM_EN                          BIT(1)
#define BAM_EN_ACCUM                    BIT(4)
#define BAM_TESTBUS_SEL_SHIFT           5
#define BAM_TESTBUS_SEL_MASK            0x3F
#define BAM_DESC_CACHE_SEL_SHIFT        13
#define BAM_DESC_CACHE_SEL_MASK         0x3
#define BAM_CACHED_DESC_STORE           BIT(15)
#define IBC_DISABLE                     BIT(16)

/* BAM REVISION */
#define REVISION_SHIFT          0
#define REVISION_MASK           0xFF
#define NUM_EES_SHIFT           8
#define NUM_EES_MASK            0xF
#define CE_BUFFER_SIZE          BIT(13)
#define AXI_ACTIVE              BIT(14)
#define USE_VMIDMT              BIT(15)
#define SECURED                 BIT(16)
#define BAM_HAS_NO_BYPASS       BIT(17)
#define HIGH_FREQUENCY_BAM      BIT(18)
#define INACTIV_TMRS_EXST       BIT(19)
#define NUM_INACTIV_TMRS        BIT(20)
#define DESC_CACHE_DEPTH_SHIFT  21
#define DESC_CACHE_DEPTH_1      (0 << DESC_CACHE_DEPTH_SHIFT)
#define DESC_CACHE_DEPTH_2      (1 << DESC_CACHE_DEPTH_SHIFT)
#define DESC_CACHE_DEPTH_3      (2 << DESC_CACHE_DEPTH_SHIFT)
#define DESC_CACHE_DEPTH_4      (3 << DESC_CACHE_DEPTH_SHIFT)
#define CMD_DESC_EN             BIT(23)
#define INACTIV_TMR_BASE_SHIFT  24
#define INACTIV_TMR_BASE_MASK   0xFF

/* BAM NUM PIPES */
#define BAM_NUM_PIPES_SHIFT             0
#define BAM_NUM_PIPES_MASK              0xFF
#define PERIPH_NON_PIPE_GRP_SHIFT       16
#define PERIPH_NON_PIP_GRP_MASK         0xFF
#define BAM_NON_PIPE_GRP_SHIFT          24
#define BAM_NON_PIPE_GRP_MASK           0xFF

/* BAM CNFG BITS */
#define BAM_PIPE_CNFG           BIT(2)
#define BAM_FULL_PIPE           BIT(11)
#define BAM_NO_EXT_P_RST        BIT(12)
#define BAM_IBC_DISABLE         BIT(13)
#define BAM_SB_CLK_REQ          BIT(14)
#define BAM_PSM_CSW_REQ         BIT(15)
#define BAM_PSM_P_RES           BIT(16)
#define BAM_AU_P_RES            BIT(17)
#define BAM_SI_P_RES            BIT(18)
#define BAM_WB_P_RES            BIT(19)
#define BAM_WB_BLK_CSW          BIT(20)
#define BAM_WB_CSW_ACK_IDL      BIT(21)
#define BAM_WB_RETR_SVPNT       BIT(22)
#define BAM_WB_DSC_AVL_P_RST    BIT(23)
#define BAM_REG_P_EN            BIT(24)
#define BAM_PSM_P_HD_DATA       BIT(25)
#define BAM_AU_ACCUMED          BIT(26)
#define BAM_CMD_ENABLE          BIT(27)

#define BAM_CNFG_BITS_DEFAULT   (BAM_PIPE_CNFG |        \
                                 BAM_NO_EXT_P_RST |     \
                                 BAM_IBC_DISABLE |      \
                                 BAM_SB_CLK_REQ |       \
                                 BAM_PSM_CSW_REQ |      \
                                 BAM_PSM_P_RES |        \
                                 BAM_AU_P_RES |         \
                                 BAM_SI_P_RES |         \
                                 BAM_WB_P_RES |         \
                                 BAM_WB_BLK_CSW |       \
                                 BAM_WB_CSW_ACK_IDL |   \
                                 BAM_WB_RETR_SVPNT |    \
                                 BAM_WB_DSC_AVL_P_RST | \
                                 BAM_REG_P_EN |         \
                                 BAM_PSM_P_HD_DATA |    \
                                 BAM_AU_ACCUMED |       \
                                 BAM_CMD_ENABLE)

/* PIPE CTRL */
#define P_EN                    BIT(1)
#define P_DIRECTION             BIT(3)
#define P_SYS_STRM              BIT(4)
#define P_SYS_MODE              BIT(5)
#define P_AUTO_EOB              BIT(6)
#define P_AUTO_EOB_SEL_SHIFT    7
#define P_AUTO_EOB_SEL_512      (0 << P_AUTO_EOB_SEL_SHIFT)
#define P_AUTO_EOB_SEL_256      (1 << P_AUTO_EOB_SEL_SHIFT)
#define P_AUTO_EOB_SEL_128      (2 << P_AUTO_EOB_SEL_SHIFT)
#define P_AUTO_EOB_SEL_64       (3 << P_AUTO_EOB_SEL_SHIFT)
#define P_PREFETCH_LIMIT_SHIFT  9
#define P_PREFETCH_LIMIT_32     (0 << P_PREFETCH_LIMIT_SHIFT)
#define P_PREFETCH_LIMIT_16     (1 << P_PREFETCH_LIMIT_SHIFT)
#define P_PREFETCH_LIMIT_4      (2 << P_PREFETCH_LIMIT_SHIFT)
#define P_WRITE_NWD             BIT(11)
#define P_LOCK_GROUP_SHIFT      16
#define P_LOCK_GROUP_MASK       0x1F

/* BAM_DESC_CNT_TRSHLD */
#define CNT_TRSHLD              0xffff
#define DEFAULT_CNT_THRSHLD     0x4

/* BAM_IRQ_SRCS */
#define BAM_IRQ                 BIT(31)
#define P_IRQ                   0x7fffffff

/* BAM_IRQ_SRCS_MSK */
#define BAM_IRQ_MSK             BAM_IRQ
#define P_IRQ_MSK               P_IRQ

/* BAM_IRQ_STTS */
#define BAM_TIMER_IRQ           BIT(4)
#define BAM_EMPTY_IRQ           BIT(3)
#define BAM_ERROR_IRQ           BIT(2)
#define BAM_HRESP_ERR_IRQ       BIT(1)

/* BAM_IRQ_CLR */
#define BAM_TIMER_CLR           BIT(4)
#define BAM_EMPTY_CLR           BIT(3)
#define BAM_ERROR_CLR           BIT(2)
#define BAM_HRESP_ERR_CLR       BIT(1)

/* BAM_IRQ_EN */
#define BAM_TIMER_EN            BIT(4)
#define BAM_EMPTY_EN            BIT(3)
#define BAM_ERROR_EN            BIT(2)
#define BAM_HRESP_ERR_EN        BIT(1)

/* BAM_P_IRQ_EN */
#define P_PRCSD_DESC_EN         BIT(0)
#define P_TIMER_EN              BIT(1)
#define P_WAKE_EN               BIT(2)
#define P_OUT_OF_DESC_EN        BIT(3)
#define P_ERR_EN                BIT(4)
#define P_TRNSFR_END_EN         BIT(5)
#define P_DEFAULT_IRQS_EN       (P_PRCSD_DESC_EN | P_ERR_EN | P_TRNSFR_END_EN)

/* BAM_P_SW_OFSTS */
#define P_SW_OFSTS_MASK         0xffff

#define BAM_DESC_FIFO_SIZE      SZ_32K
#define MAX_DESCRIPTORS (BAM_DESC_FIFO_SIZE / sizeof(struct bam_desc_hw) - 1)
#define BAM_FIFO_SIZE   (SZ_32K - 8)
#define IS_BUSY(chan)   (CIRC_SPACE(bchan->tail, bchan->head,\
                         MAX_DESCRIPTORS + 1) == 0)

struct bam_chan {
        struct virt_dma_chan vc;

        struct bam_device *bdev;

        /* configuration from device tree */
        u32 id;

        /* runtime configuration */
        struct dma_slave_config slave;

        /* fifo storage */
        struct bam_desc_hw *fifo_virt;
        dma_addr_t fifo_phys;

        /* fifo markers */
        unsigned short head;            /* start of active descriptor entries */
        unsigned short tail;            /* end of active descriptor entries */

        unsigned int initialized;       /* is the channel hw initialized? */
        unsigned int paused;            /* is the channel paused? */
        unsigned int reconfigure;       /* new slave config? */
        /* list of descriptors currently processed */
        struct list_head desc_list;

        struct list_head node;
};

static inline struct bam_chan *to_bam_chan(struct dma_chan *common)
{
        return container_of(common, struct bam_chan, vc.chan);
}

struct bam_device {
        void __iomem *regs;
        struct device *dev;
        struct dma_device common;
        struct bam_chan *channels;
        u32 num_channels;
        u32 num_ees;

        /* execution environment ID, from DT */
        u32 ee;
        bool controlled_remotely;

        const struct reg_offset_data *layout;

        struct clk *bamclk;
        int irq;

        /* dma start transaction tasklet */
        struct tasklet_struct task;
};

/**
 * bam_addr - returns BAM register address
 * @bdev: bam device
 * @pipe: pipe instance (ignored when register doesn't have multiple instances)
 * @reg:  register enum
 */
static inline void __iomem *bam_addr(struct bam_device *bdev, u32 pipe,
                enum bam_reg reg)
{
        const struct reg_offset_data r = bdev->layout[reg];

        return bdev->regs + r.base_offset +
                r.pipe_mult * pipe +
                r.evnt_mult * pipe +
                r.ee_mult * bdev->ee;
}

/**
 * bam_reset_channel - Reset individual BAM DMA channel
 * @bchan: bam channel
 *
 * This function resets a specific BAM channel
 */
static void bam_reset_channel(struct bam_chan *bchan)
{
        struct bam_device *bdev = bchan->bdev;

        lockdep_assert_held(&bchan->vc.lock);

        /* reset channel */
        writel_relaxed(1, bam_addr(bdev, bchan->id, BAM_P_RST));
        writel_relaxed(0, bam_addr(bdev, bchan->id, BAM_P_RST));

        /* don't allow cpu to reorder BAM register accesses done after this */
        wmb();

        /* make sure hw is initialized when channel is used the first time  */
        bchan->initialized = 0;
}

/**
 * bam_chan_init_hw - Initialize channel hardware
 * @bchan: bam channel
 * @dir: DMA transfer direction
 *
 * This function resets and initializes the BAM channel
 */
static void bam_chan_init_hw(struct bam_chan *bchan,
        enum dma_transfer_direction dir)
{
        struct bam_device *bdev = bchan->bdev;
        u32 val;

        /* Reset the channel to clear internal state of the FIFO */
        bam_reset_channel(bchan);

        /*
         * write out 8 byte aligned address.  We have enough space for this
         * because we allocated 1 more descriptor (8 bytes) than we can use
         */
        writel_relaxed(ALIGN(bchan->fifo_phys, sizeof(struct bam_desc_hw)),
                        bam_addr(bdev, bchan->id, BAM_P_DESC_FIFO_ADDR));
        writel_relaxed(BAM_FIFO_SIZE,
                        bam_addr(bdev, bchan->id, BAM_P_FIFO_SIZES));

        /* enable the per pipe interrupts, enable EOT, ERR, and INT irqs */
        writel_relaxed(P_DEFAULT_IRQS_EN,
                        bam_addr(bdev, bchan->id, BAM_P_IRQ_EN));

        /* unmask the specific pipe and EE combo */
        val = readl_relaxed(bam_addr(bdev, 0, BAM_IRQ_SRCS_MSK_EE));
        val |= BIT(bchan->id);
        writel_relaxed(val, bam_addr(bdev, 0, BAM_IRQ_SRCS_MSK_EE));

        /* don't allow cpu to reorder the channel enable done below */
        wmb();

        /* set fixed direction and mode, then enable channel */
        val = P_EN | P_SYS_MODE;
        if (dir == DMA_DEV_TO_MEM)
                val |= P_DIRECTION;

        writel_relaxed(val, bam_addr(bdev, bchan->id, BAM_P_CTRL));

        bchan->initialized = 1;

        /* init FIFO pointers */
        bchan->head = 0;
        bchan->tail = 0;
}

/**
 * bam_alloc_chan - Allocate channel resources for DMA channel.
 * @chan: specified channel
 *
 * This function allocates the FIFO descriptor memory
 */
static int bam_alloc_chan(struct dma_chan *chan)
{
        struct bam_chan *bchan = to_bam_chan(chan);
        struct bam_device *bdev = bchan->bdev;

        if (bchan->fifo_virt)
                return 0;

        /* allocate FIFO descriptor space, but only if necessary */
        bchan->fifo_virt = dma_alloc_wc(bdev->dev, BAM_DESC_FIFO_SIZE,
                                        &bchan->fifo_phys, GFP_KERNEL);

        if (!bchan->fifo_virt) {
                dev_err(bdev->dev, "Failed to allocate desc fifo\n");
                return -ENOMEM;
        }

        return 0;
}

static int bam_pm_runtime_get_sync(struct device *dev)
{
        if (pm_runtime_enabled(dev))
                return pm_runtime_get_sync(dev);

        return 0;
}

/**
 * bam_free_chan - Frees dma resources associated with specific channel
 * @chan: specified channel
 *
 * Free the allocated fifo descriptor memory and channel resources
 *
 */
static void bam_free_chan(struct dma_chan *chan)
{
        struct bam_chan *bchan = to_bam_chan(chan);
        struct bam_device *bdev = bchan->bdev;
        u32 val;
        unsigned long flags;
        int ret;

        ret = bam_pm_runtime_get_sync(bdev->dev);
        if (ret < 0)
                return;

        vchan_free_chan_resources(to_virt_chan(chan));

        if (!list_empty(&bchan->desc_list)) {
                dev_err(bchan->bdev->dev, "Cannot free busy channel\n");
                goto err;
        }

        spin_lock_irqsave(&bchan->vc.lock, flags);
        bam_reset_channel(bchan);
        spin_unlock_irqrestore(&bchan->vc.lock, flags);

        dma_free_wc(bdev->dev, BAM_DESC_FIFO_SIZE, bchan->fifo_virt,
                    bchan->fifo_phys);
        bchan->fifo_virt = NULL;

        /* mask irq for pipe/channel */
        val = readl_relaxed(bam_addr(bdev, 0, BAM_IRQ_SRCS_MSK_EE));
        val &= ~BIT(bchan->id);
        writel_relaxed(val, bam_addr(bdev, 0, BAM_IRQ_SRCS_MSK_EE));

        /* disable irq */
        writel_relaxed(0, bam_addr(bdev, bchan->id, BAM_P_IRQ_EN));

err:
        pm_runtime_mark_last_busy(bdev->dev);
        pm_runtime_put_autosuspend(bdev->dev);
}

/**
 * bam_slave_config - set slave configuration for channel
 * @chan: dma channel
 * @cfg: slave configuration
 *
 * Sets slave configuration for channel
 *
 */
static int bam_slave_config(struct dma_chan *chan,
                            struct dma_slave_config *cfg)
{
        struct bam_chan *bchan = to_bam_chan(chan);
        unsigned long flag;

        spin_lock_irqsave(&bchan->vc.lock, flag);
        memcpy(&bchan->slave, cfg, sizeof(*cfg));
        bchan->reconfigure = 1;
        spin_unlock_irqrestore(&bchan->vc.lock, flag);

        return 0;
}

/**
 * bam_prep_slave_sg - Prep slave sg transaction
 *
 * @chan: dma channel
 * @sgl: scatter gather list
 * @sg_len: length of sg
 * @direction: DMA transfer direction
 * @flags: DMA flags
 * @context: transfer context (unused)
 */
static struct dma_async_tx_descriptor *bam_prep_slave_sg(struct dma_chan *chan,
        struct scatterlist *sgl, unsigned int sg_len,
        enum dma_transfer_direction direction, unsigned long flags,
        void *context)
{
        struct bam_chan *bchan = to_bam_chan(chan);
        struct bam_device *bdev = bchan->bdev;
        struct bam_async_desc *async_desc;
        struct scatterlist *sg;
        u32 i;
        struct bam_desc_hw *desc;
        unsigned int num_alloc = 0;


        if (!is_slave_direction(direction)) {
                dev_err(bdev->dev, "invalid dma direction\n");
                return NULL;
        }

        /* calculate number of required entries */
        for_each_sg(sgl, sg, sg_len, i)
                num_alloc += DIV_ROUND_UP(sg_dma_len(sg), BAM_FIFO_SIZE);

        /* allocate enough room to accomodate the number of entries */
        async_desc = kzalloc(struct_size(async_desc, desc, num_alloc),
                             GFP_NOWAIT);

        if (!async_desc)
                goto err_out;

        if (flags & DMA_PREP_FENCE)
                async_desc->flags |= DESC_FLAG_NWD;

        if (flags & DMA_PREP_INTERRUPT)
                async_desc->flags |= DESC_FLAG_EOT;

        async_desc->num_desc = num_alloc;
        async_desc->curr_desc = async_desc->desc;
        async_desc->dir = direction;

        /* fill in temporary descriptors */
        desc = async_desc->desc;
        for_each_sg(sgl, sg, sg_len, i) {
                unsigned int remainder = sg_dma_len(sg);
                unsigned int curr_offset = 0;

                do {
                        if (flags & DMA_PREP_CMD)
                                desc->flags |= cpu_to_le16(DESC_FLAG_CMD);

                        desc->addr = cpu_to_le32(sg_dma_address(sg) +
                                                 curr_offset);

                        if (remainder > BAM_FIFO_SIZE) {
                                desc->size = cpu_to_le16(BAM_FIFO_SIZE);
                                remainder -= BAM_FIFO_SIZE;
                                curr_offset += BAM_FIFO_SIZE;
                        } else {
                                desc->size = cpu_to_le16(remainder);
                                remainder = 0;
                        }

                        async_desc->length += le16_to_cpu(desc->size);
                        desc++;
                } while (remainder > 0);
        }

        return vchan_tx_prep(&bchan->vc, &async_desc->vd, flags);

err_out:
        kfree(async_desc);
        return NULL;
}

/**
 * bam_dma_terminate_all - terminate all transactions on a channel
 * @chan: bam dma channel
 *
 * Dequeues and frees all transactions
 * No callbacks are done
 *
 */
static int bam_dma_terminate_all(struct dma_chan *chan)
{
        struct bam_chan *bchan = to_bam_chan(chan);
        struct bam_async_desc *async_desc, *tmp;
        unsigned long flag;
        LIST_HEAD(head);

        /* remove all transactions, including active transaction */
        spin_lock_irqsave(&bchan->vc.lock, flag);
        /*
         * If we have transactions queued, then some might be committed to the
         * hardware in the desc fifo.  The only way to reset the desc fifo is
         * to do a hardware reset (either by pipe or the entire block).
         * bam_chan_init_hw() will trigger a pipe reset, and also reinit the
         * pipe.  If the pipe is left disabled (default state after pipe reset)
         * and is accessed by a connected hardware engine, a fatal error in
         * the BAM will occur.  There is a small window where this could happen
         * with bam_chan_init_hw(), but it is assumed that the caller has
         * stopped activity on any attached hardware engine.  Make sure to do
         * this first so that the BAM hardware doesn't cause memory corruption
         * by accessing freed resources.
         */
        if (!list_empty(&bchan->desc_list)) {
                async_desc = list_first_entry(&bchan->desc_list,
                                              struct bam_async_desc, desc_node);
                bam_chan_init_hw(bchan, async_desc->dir);
        }

        list_for_each_entry_safe(async_desc, tmp,
                                 &bchan->desc_list, desc_node) {
                list_add(&async_desc->vd.node, &bchan->vc.desc_issued);
                list_del(&async_desc->desc_node);
        }

        vchan_get_all_descriptors(&bchan->vc, &head);
        spin_unlock_irqrestore(&bchan->vc.lock, flag);

        vchan_dma_desc_free_list(&bchan->vc, &head);

        return 0;
}

/**
 * bam_pause - Pause DMA channel
 * @chan: dma channel
 *
 */
static int bam_pause(struct dma_chan *chan)
{
        struct bam_chan *bchan = to_bam_chan(chan);
        struct bam_device *bdev = bchan->bdev;
        unsigned long flag;
        int ret;

        ret = bam_pm_runtime_get_sync(bdev->dev);
        if (ret < 0)
                return ret;

        spin_lock_irqsave(&bchan->vc.lock, flag);
        writel_relaxed(1, bam_addr(bdev, bchan->id, BAM_P_HALT));
        bchan->paused = 1;
        spin_unlock_irqrestore(&bchan->vc.lock, flag);
        pm_runtime_mark_last_busy(bdev->dev);
        pm_runtime_put_autosuspend(bdev->dev);

        return 0;
}

/**
 * bam_resume - Resume DMA channel operations
 * @chan: dma channel
 *
 */
static int bam_resume(struct dma_chan *chan)
{
        struct bam_chan *bchan = to_bam_chan(chan);
        struct bam_device *bdev = bchan->bdev;
        unsigned long flag;
        int ret;

        ret = bam_pm_runtime_get_sync(bdev->dev);
        if (ret < 0)
                return ret;

        spin_lock_irqsave(&bchan->vc.lock, flag);
        writel_relaxed(0, bam_addr(bdev, bchan->id, BAM_P_HALT));
        bchan->paused = 0;
        spin_unlock_irqrestore(&bchan->vc.lock, flag);
        pm_runtime_mark_last_busy(bdev->dev);
        pm_runtime_put_autosuspend(bdev->dev);

        return 0;
}

/**
 * process_channel_irqs - processes the channel interrupts
 * @bdev: bam controller
 *
 * This function processes the channel interrupts
 *
 */
static u32 process_channel_irqs(struct bam_device *bdev)
{
        u32 i, srcs, pipe_stts, offset, avail;
        unsigned long flags;
        struct bam_async_desc *async_desc, *tmp;

        srcs = readl_relaxed(bam_addr(bdev, 0, BAM_IRQ_SRCS_EE));

        /* return early if no pipe/channel interrupts are present */
        if (!(srcs & P_IRQ))
                return srcs;

        for (i = 0; i < bdev->num_channels; i++) {
                struct bam_chan *bchan = &bdev->channels[i];

                if (!(srcs & BIT(i)))
                        continue;

                /* clear pipe irq */
                pipe_stts = readl_relaxed(bam_addr(bdev, i, BAM_P_IRQ_STTS));

                writel_relaxed(pipe_stts, bam_addr(bdev, i, BAM_P_IRQ_CLR));

                spin_lock_irqsave(&bchan->vc.lock, flags);

                offset = readl_relaxed(bam_addr(bdev, i, BAM_P_SW_OFSTS)) &
                                       P_SW_OFSTS_MASK;
                offset /= sizeof(struct bam_desc_hw);

                /* Number of bytes available to read */
                avail = CIRC_CNT(offset, bchan->head, MAX_DESCRIPTORS + 1);

                if (offset < bchan->head)
                        avail--;

                list_for_each_entry_safe(async_desc, tmp,
                                         &bchan->desc_list, desc_node) {
                        /* Not enough data to read */
                        if (avail < async_desc->xfer_len)
                                break;

                        /* manage FIFO */
                        bchan->head += async_desc->xfer_len;
                        bchan->head %= MAX_DESCRIPTORS;

                        async_desc->num_desc -= async_desc->xfer_len;
                        async_desc->curr_desc += async_desc->xfer_len;
                        avail -= async_desc->xfer_len;

                        /*
                         * if complete, process cookie. Otherwise
                         * push back to front of desc_issued so that
                         * it gets restarted by the tasklet
                         */
                        if (!async_desc->num_desc) {
                                vchan_cookie_complete(&async_desc->vd);
                        } else {
                                list_add(&async_desc->vd.node,
                                         &bchan->vc.desc_issued);
                        }
                        list_del(&async_desc->desc_node);
                }

                spin_unlock_irqrestore(&bchan->vc.lock, flags);
        }

        return srcs;
}

/**
 * bam_dma_irq - irq handler for bam controller
 * @irq: IRQ of interrupt
 * @data: callback data
 *
 * IRQ handler for the bam controller
 */
static irqreturn_t bam_dma_irq(int irq, void *data)
{
        struct bam_device *bdev = data;
        u32 clr_mask = 0, srcs = 0;
        int ret;

        srcs |= process_channel_irqs(bdev);

        /* kick off tasklet to start next dma transfer */
        if (srcs & P_IRQ)
                tasklet_schedule(&bdev->task);

        ret = bam_pm_runtime_get_sync(bdev->dev);
        if (ret < 0)
                return ret;

        if (srcs & BAM_IRQ) {
                clr_mask = readl_relaxed(bam_addr(bdev, 0, BAM_IRQ_STTS));

                /*
                 * don't allow reorder of the various accesses to the BAM
                 * registers
                 */
                mb();

                writel_relaxed(clr_mask, bam_addr(bdev, 0, BAM_IRQ_CLR));
        }

        pm_runtime_mark_last_busy(bdev->dev);
        pm_runtime_put_autosuspend(bdev->dev);

        return IRQ_HANDLED;
}

/**
 * bam_tx_status - returns status of transaction
 * @chan: dma channel
 * @cookie: transaction cookie
 * @txstate: DMA transaction state
 *
 * Return status of dma transaction
 */
static enum dma_status bam_tx_status(struct dma_chan *chan, dma_cookie_t cookie,
                struct dma_tx_state *txstate)
{
        struct bam_chan *bchan = to_bam_chan(chan);
        struct bam_async_desc *async_desc;
        struct virt_dma_desc *vd;
        int ret;
        size_t residue = 0;
        unsigned int i;
        unsigned long flags;

        ret = dma_cookie_status(chan, cookie, txstate);
        if (ret == DMA_COMPLETE)
                return ret;

        if (!txstate)
                return bchan->paused ? DMA_PAUSED : ret;

        spin_lock_irqsave(&bchan->vc.lock, flags);
        vd = vchan_find_desc(&bchan->vc, cookie);
        if (vd) {
                residue = container_of(vd, struct bam_async_desc, vd)->length;
        } else {
                list_for_each_entry(async_desc, &bchan->desc_list, desc_node) {
                        if (async_desc->vd.tx.cookie != cookie)
                                continue;

                        for (i = 0; i < async_desc->num_desc; i++)
                                residue += le16_to_cpu(
                                                async_desc->curr_desc[i].size);
                }
        }

        spin_unlock_irqrestore(&bchan->vc.lock, flags);

        dma_set_residue(txstate, residue);

        if (ret == DMA_IN_PROGRESS && bchan->paused)
                ret = DMA_PAUSED;

        return ret;
}

/**
 * bam_apply_new_config
 * @bchan: bam dma channel
 * @dir: DMA direction
 */
static void bam_apply_new_config(struct bam_chan *bchan,
        enum dma_transfer_direction dir)
{
        struct bam_device *bdev = bchan->bdev;
        u32 maxburst;

        if (!bdev->controlled_remotely) {
                if (dir == DMA_DEV_TO_MEM)
                        maxburst = bchan->slave.src_maxburst;
                else
                        maxburst = bchan->slave.dst_maxburst;

                writel_relaxed(maxburst,
                               bam_addr(bdev, 0, BAM_DESC_CNT_TRSHLD));
        }

        bchan->reconfigure = 0;
}

/**
 * bam_start_dma - start next transaction
 * @bchan: bam dma channel
 */
static void bam_start_dma(struct bam_chan *bchan)
{
        struct virt_dma_desc *vd = vchan_next_desc(&bchan->vc);
        struct bam_device *bdev = bchan->bdev;
        struct bam_async_desc *async_desc = NULL;
        struct bam_desc_hw *desc;
        struct bam_desc_hw *fifo = PTR_ALIGN(bchan->fifo_virt,
                                        sizeof(struct bam_desc_hw));
        int ret;
        unsigned int avail;
        struct dmaengine_desc_callback cb;

        lockdep_assert_held(&bchan->vc.lock);

        if (!vd)
                return;

        ret = bam_pm_runtime_get_sync(bdev->dev);
        if (ret < 0)
                return;

        while (vd && !IS_BUSY(bchan)) {
                list_del(&vd->node);

                async_desc = container_of(vd, struct bam_async_desc, vd);

                /* on first use, initialize the channel hardware */
                if (!bchan->initialized)
                        bam_chan_init_hw(bchan, async_desc->dir);

                /* apply new slave config changes, if necessary */
                if (bchan->reconfigure)
                        bam_apply_new_config(bchan, async_desc->dir);

                desc = async_desc->curr_desc;
                avail = CIRC_SPACE(bchan->tail, bchan->head,
                                   MAX_DESCRIPTORS + 1);

                if (async_desc->num_desc > avail)
                        async_desc->xfer_len = avail;
                else
                        async_desc->xfer_len = async_desc->num_desc;

                /* set any special flags on the last descriptor */
                if (async_desc->num_desc == async_desc->xfer_len)
                        desc[async_desc->xfer_len - 1].flags |=
                                                cpu_to_le16(async_desc->flags);

                vd = vchan_next_desc(&bchan->vc);

                dmaengine_desc_get_callback(&async_desc->vd.tx, &cb);

                /*
                 * An interrupt is generated at this desc, if
                 *  - FIFO is FULL.
                 *  - No more descriptors to add.
                 *  - If a callback completion was requested for this DESC,
                 *     In this case, BAM will deliver the completion callback
                 *     for this desc and continue processing the next desc.
                 */
                if (((avail <= async_desc->xfer_len) || !vd ||
                     dmaengine_desc_callback_valid(&cb)) &&
                    !(async_desc->flags & DESC_FLAG_EOT))
                        desc[async_desc->xfer_len - 1].flags |=
                                cpu_to_le16(DESC_FLAG_INT);

                if (bchan->tail + async_desc->xfer_len > MAX_DESCRIPTORS) {
                        u32 partial = MAX_DESCRIPTORS - bchan->tail;

                        memcpy(&fifo[bchan->tail], desc,
                               partial * sizeof(struct bam_desc_hw));
                        memcpy(fifo, &desc[partial],
                               (async_desc->xfer_len - partial) *
                                sizeof(struct bam_desc_hw));
                } else {
                        memcpy(&fifo[bchan->tail], desc,
                               async_desc->xfer_len *
                               sizeof(struct bam_desc_hw));
                }

                bchan->tail += async_desc->xfer_len;
                bchan->tail %= MAX_DESCRIPTORS;
                list_add_tail(&async_desc->desc_node, &bchan->desc_list);
        }

        /* ensure descriptor writes and dma start not reordered */
        wmb();
        writel_relaxed(bchan->tail * sizeof(struct bam_desc_hw),
                        bam_addr(bdev, bchan->id, BAM_P_EVNT_REG));

        pm_runtime_mark_last_busy(bdev->dev);
        pm_runtime_put_autosuspend(bdev->dev);
}

/**
 * dma_tasklet - DMA IRQ tasklet
 * @t: tasklet argument (bam controller structure)
 *
 * Sets up next DMA operation and then processes all completed transactions
 */
static void dma_tasklet(struct tasklet_struct *t)
{
        struct bam_device *bdev = from_tasklet(bdev, t, task);
        struct bam_chan *bchan;
        unsigned long flags;
        unsigned int i;

        /* go through the channels and kick off transactions */
        for (i = 0; i < bdev->num_channels; i++) {
                bchan = &bdev->channels[i];
                spin_lock_irqsave(&bchan->vc.lock, flags);

                if (!list_empty(&bchan->vc.desc_issued) && !IS_BUSY(bchan))
                        bam_start_dma(bchan);
                spin_unlock_irqrestore(&bchan->vc.lock, flags);
        }

}

/**
 * bam_issue_pending - starts pending transactions
 * @chan: dma channel
 *
 * Calls tasklet directly which in turn starts any pending transactions
 */
static void bam_issue_pending(struct dma_chan *chan)
{
        struct bam_chan *bchan = to_bam_chan(chan);
        unsigned long flags;

        spin_lock_irqsave(&bchan->vc.lock, flags);

        /* if work pending and idle, start a transaction */
        if (vchan_issue_pending(&bchan->vc) && !IS_BUSY(bchan))
                bam_start_dma(bchan);

        spin_unlock_irqrestore(&bchan->vc.lock, flags);
}

/**
 * bam_dma_free_desc - free descriptor memory
 * @vd: virtual descriptor
 *
 */
static void bam_dma_free_desc(struct virt_dma_desc *vd)
{
        struct bam_async_desc *async_desc = container_of(vd,
                        struct bam_async_desc, vd);

        kfree(async_desc);
}

static struct dma_chan *bam_dma_xlate(struct of_phandle_args *dma_spec,
                struct of_dma *of)
{
        struct bam_device *bdev = container_of(of->of_dma_data,
                                        struct bam_device, common);
        unsigned int request;

        if (dma_spec->args_count != 1)
                return NULL;

        request = dma_spec->args[0];
        if (request >= bdev->num_channels)
                return NULL;

        return dma_get_slave_channel(&(bdev->channels[request].vc.chan));
}

/**
 * bam_init
 * @bdev: bam device
 *
 * Initialization helper for global bam registers
 */
static int bam_init(struct bam_device *bdev)
{
        u32 val;

        /* read revision and configuration information */
        if (!bdev->num_ees) {
                val = readl_relaxed(bam_addr(bdev, 0, BAM_REVISION));
                bdev->num_ees = (val >> NUM_EES_SHIFT) & NUM_EES_MASK;
        }

        /* check that configured EE is within range */
        if (bdev->ee >= bdev->num_ees)
                return -EINVAL;

        if (!bdev->num_channels) {
                val = readl_relaxed(bam_addr(bdev, 0, BAM_NUM_PIPES));
                bdev->num_channels = val & BAM_NUM_PIPES_MASK;
        }

        if (bdev->controlled_remotely)
                return 0;

        /* s/w reset bam */
        /* after reset all pipes are disabled and idle */
        val = readl_relaxed(bam_addr(bdev, 0, BAM_CTRL));
        val |= BAM_SW_RST;
        writel_relaxed(val, bam_addr(bdev, 0, BAM_CTRL));
        val &= ~BAM_SW_RST;
        writel_relaxed(val, bam_addr(bdev, 0, BAM_CTRL));

        /* make sure previous stores are visible before enabling BAM */
        wmb();

        /* enable bam */
        val |= BAM_EN;
        writel_relaxed(val, bam_addr(bdev, 0, BAM_CTRL));

        /* set descriptor threshhold, start with 4 bytes */
        writel_relaxed(DEFAULT_CNT_THRSHLD,
                        bam_addr(bdev, 0, BAM_DESC_CNT_TRSHLD));

        /* Enable default set of h/w workarounds, ie all except BAM_FULL_PIPE */
        writel_relaxed(BAM_CNFG_BITS_DEFAULT, bam_addr(bdev, 0, BAM_CNFG_BITS));

        /* enable irqs for errors */
        writel_relaxed(BAM_ERROR_EN | BAM_HRESP_ERR_EN,
                        bam_addr(bdev, 0, BAM_IRQ_EN));

        /* unmask global bam interrupt */
        writel_relaxed(BAM_IRQ_MSK, bam_addr(bdev, 0, BAM_IRQ_SRCS_MSK_EE));

        return 0;
}

static void bam_channel_init(struct bam_device *bdev, struct bam_chan *bchan,
        u32 index)
{
        bchan->id = index;
        bchan->bdev = bdev;

        vchan_init(&bchan->vc, &bdev->common);
        bchan->vc.desc_free = bam_dma_free_desc;
        INIT_LIST_HEAD(&bchan->desc_list);
}

static const struct of_device_id bam_of_match[] = {
        { .compatible = "qcom,bam-v1.3.0", .data = &bam_v1_3_reg_info },
        { .compatible = "qcom,bam-v1.4.0", .data = &bam_v1_4_reg_info },
        { .compatible = "qcom,bam-v1.7.0", .data = &bam_v1_7_reg_info },
        {}
};

MODULE_DEVICE_TABLE(of, bam_of_match);

static int bam_dma_probe(struct platform_device *pdev)
{
        struct bam_device *bdev;
        const struct of_device_id *match;
        struct resource *iores;
        int ret, i;

        bdev = devm_kzalloc(&pdev->dev, sizeof(*bdev), GFP_KERNEL);
        if (!bdev)
                return -ENOMEM;

        bdev->dev = &pdev->dev;

        match = of_match_node(bam_of_match, pdev->dev.of_node);
        if (!match) {
                dev_err(&pdev->dev, "Unsupported BAM module\n");
                return -ENODEV;
        }

        bdev->layout = match->data;

        iores = platform_get_resource(pdev, IORESOURCE_MEM, 0);
        bdev->regs = devm_ioremap_resource(&pdev->dev, iores);
        if (IS_ERR(bdev->regs))
                return PTR_ERR(bdev->regs);

        bdev->irq = platform_get_irq(pdev, 0);
        if (bdev->irq < 0)
                return bdev->irq;

        ret = of_property_read_u32(pdev->dev.of_node, "qcom,ee", &bdev->ee);
        if (ret) {
                dev_err(bdev->dev, "Execution environment unspecified\n");
                return ret;
        }

        bdev->controlled_remotely = of_property_read_bool(pdev->dev.of_node,
                                                "qcom,controlled-remotely");

        if (bdev->controlled_remotely) {
                ret = of_property_read_u32(pdev->dev.of_node, "num-channels",
                                           &bdev->num_channels);
                if (ret)
                        dev_err(bdev->dev, "num-channels unspecified in dt\n");

                ret = of_property_read_u32(pdev->dev.of_node, "qcom,num-ees",
                                           &bdev->num_ees);
                if (ret)
                        dev_err(bdev->dev, "num-ees unspecified in dt\n");
        }

        bdev->bamclk = devm_clk_get(bdev->dev, "bam_clk");
        if (IS_ERR(bdev->bamclk)) {
                if (!bdev->controlled_remotely)
                        return PTR_ERR(bdev->bamclk);

                bdev->bamclk = NULL;
        }

        ret = clk_prepare_enable(bdev->bamclk);
        if (ret) {
                dev_err(bdev->dev, "failed to prepare/enable clock\n");
                return ret;
        }

        ret = bam_init(bdev);
        if (ret)
                goto err_disable_clk;

        tasklet_setup(&bdev->task, dma_tasklet);

        bdev->channels = devm_kcalloc(bdev->dev, bdev->num_channels,
                                sizeof(*bdev->channels), GFP_KERNEL);

        if (!bdev->channels) {
                ret = -ENOMEM;
                goto err_tasklet_kill;
        }

        /* allocate and initialize channels */
        INIT_LIST_HEAD(&bdev->common.channels);

        for (i = 0; i < bdev->num_channels; i++)
                bam_channel_init(bdev, &bdev->channels[i], i);

        ret = devm_request_irq(bdev->dev, bdev->irq, bam_dma_irq,
                        IRQF_TRIGGER_HIGH, "bam_dma", bdev);
        if (ret)
                goto err_bam_channel_exit;

        /* set max dma segment size */
        bdev->common.dev = bdev->dev;
        ret = dma_set_max_seg_size(bdev->common.dev, BAM_FIFO_SIZE);
        if (ret) {
                dev_err(bdev->dev, "cannot set maximum segment size\n");
                goto err_bam_channel_exit;
        }

        platform_set_drvdata(pdev, bdev);

        /* set capabilities */
        dma_cap_zero(bdev->common.cap_mask);
        dma_cap_set(DMA_SLAVE, bdev->common.cap_mask);

        /* initialize dmaengine apis */
        bdev->common.directions = BIT(DMA_DEV_TO_MEM) | BIT(DMA_MEM_TO_DEV);
        bdev->common.residue_granularity = DMA_RESIDUE_GRANULARITY_SEGMENT;
        bdev->common.src_addr_widths = DMA_SLAVE_BUSWIDTH_4_BYTES;
        bdev->common.dst_addr_widths = DMA_SLAVE_BUSWIDTH_4_BYTES;
        bdev->common.device_alloc_chan_resources = bam_alloc_chan;
        bdev->common.device_free_chan_resources = bam_free_chan;
        bdev->common.device_prep_slave_sg = bam_prep_slave_sg;
        bdev->common.device_config = bam_slave_config;
        bdev->common.device_pause = bam_pause;
        bdev->common.device_resume = bam_resume;
        bdev->common.device_terminate_all = bam_dma_terminate_all;
        bdev->common.device_issue_pending = bam_issue_pending;
        bdev->common.device_tx_status = bam_tx_status;
        bdev->common.dev = bdev->dev;

        ret = dma_async_device_register(&bdev->common);
        if (ret) {
                dev_err(bdev->dev, "failed to register dma async device\n");
                goto err_bam_channel_exit;
        }

        ret = of_dma_controller_register(pdev->dev.of_node, bam_dma_xlate,
                                        &bdev->common);
        if (ret)
                goto err_unregister_dma;

        if (bdev->controlled_remotely) {
                pm_runtime_disable(&pdev->dev);
                return 0;
        }

        pm_runtime_irq_safe(&pdev->dev);
        pm_runtime_set_autosuspend_delay(&pdev->dev, BAM_DMA_AUTOSUSPEND_DELAY);
        pm_runtime_use_autosuspend(&pdev->dev);
        pm_runtime_mark_last_busy(&pdev->dev);
        pm_runtime_set_active(&pdev->dev);
        pm_runtime_enable(&pdev->dev);

        return 0;

err_unregister_dma:
        dma_async_device_unregister(&bdev->common);
err_bam_channel_exit:
        for (i = 0; i < bdev->num_channels; i++)
                tasklet_kill(&bdev->channels[i].vc.task);
err_tasklet_kill:
        tasklet_kill(&bdev->task);
err_disable_clk:
        clk_disable_unprepare(bdev->bamclk);

        return ret;
}

static int bam_dma_remove(struct platform_device *pdev)
{
        struct bam_device *bdev = platform_get_drvdata(pdev);
        u32 i;

        pm_runtime_force_suspend(&pdev->dev);

        of_dma_controller_free(pdev->dev.of_node);
        dma_async_device_unregister(&bdev->common);

        /* mask all interrupts for this execution environment */
        writel_relaxed(0, bam_addr(bdev, 0,  BAM_IRQ_SRCS_MSK_EE));

        devm_free_irq(bdev->dev, bdev->irq, bdev);

        for (i = 0; i < bdev->num_channels; i++) {
                bam_dma_terminate_all(&bdev->channels[i].vc.chan);
                tasklet_kill(&bdev->channels[i].vc.task);

                if (!bdev->channels[i].fifo_virt)
                        continue;

                dma_free_wc(bdev->dev, BAM_DESC_FIFO_SIZE,
                            bdev->channels[i].fifo_virt,
                            bdev->channels[i].fifo_phys);
        }

        tasklet_kill(&bdev->task);

        clk_disable_unprepare(bdev->bamclk);

        return 0;
}

static int __maybe_unused bam_dma_runtime_suspend(struct device *dev)
{
        struct bam_device *bdev = dev_get_drvdata(dev);

        clk_disable(bdev->bamclk);

        return 0;
}

static int __maybe_unused bam_dma_runtime_resume(struct device *dev)
{
        struct bam_device *bdev = dev_get_drvdata(dev);
        int ret;

        ret = clk_enable(bdev->bamclk);
        if (ret < 0) {
                dev_err(dev, "clk_enable failed: %d\n", ret);
                return ret;
        }

        return 0;
}

static int __maybe_unused bam_dma_suspend(struct device *dev)
{
        struct bam_device *bdev = dev_get_drvdata(dev);

        if (!bdev->controlled_remotely)
                pm_runtime_force_suspend(dev);

        clk_unprepare(bdev->bamclk);

        return 0;
}

static int __maybe_unused bam_dma_resume(struct device *dev)
{
        struct bam_device *bdev = dev_get_drvdata(dev);
        int ret;

        ret = clk_prepare(bdev->bamclk);
        if (ret)
                return ret;

        if (!bdev->controlled_remotely)
                pm_runtime_force_resume(dev);

        return 0;
}

static const struct dev_pm_ops bam_dma_pm_ops = {
        SET_LATE_SYSTEM_SLEEP_PM_OPS(bam_dma_suspend, bam_dma_resume)
        SET_RUNTIME_PM_OPS(bam_dma_runtime_suspend, bam_dma_runtime_resume,
                                NULL)
};

static struct platform_driver bam_dma_driver = {
        .probe = bam_dma_probe,
        .remove = bam_dma_remove,
        .driver = {
                .name = "bam-dma-engine",
                .pm = &bam_dma_pm_ops,
                .of_match_table = bam_of_match,
        },
};

module_platform_driver(bam_dma_driver);

MODULE_AUTHOR("Andy Gross <agross@codeaurora.org>");
MODULE_DESCRIPTION("QCOM BAM DMA engine driver");
MODULE_LICENSE("GPL v2");