// SPDX-License-Identifier: GPL-2.0+
#include <linux/module.h>
#include <linux/pci.h>
#include <linux/types.h>
#include <linux/export.h>
#include <linux/slab.h>
#include <asm/io.h>
#include <linux/io.h>
#include <linux/mfd/core.h>
#include <linux/platform_device.h>
#include <linux/ioport.h>
#include <linux/uio_driver.h>
#include "pcie.h"

/*  Core (Resource) Table Layout:
 *      one Resource per record (8 bytes)
 *                 6         5         4         3         2         1         0
 *              3210987654321098765432109876543210987654321098765432109876543210
 *              IIIIIIIIIIII                                                        Core Type    [up to 4095 types]
 *                          D                                                       S2C DMA Present
 *                           DDD                                                    S2C DMA Channel Number    [up to 8 channels]
 *                              LLLLLLLLLLLLLLLL                                    Register Count (64-bit registers)    [up to 65535 registers]
 *                                              OOOOOOOOOOOOOOOO                    Core Offset (in 4kB blocks)    [up to 65535 cores]
 *                                                              D                   C2S DMA Present
 *                                                               DDD                C2S DMA Channel Number    [up to 8 channels]
 *                                                                  II              IRQ Count [0 to 3 IRQs per core]
                                                                      1111111000
 *                                                                    IIIIIII       IRQ Base Number [up to 128 IRQs per card]
 *                                                                           ___    Spare
 *
 */

#define KPC_OLD_DMA_CH_NUM(present, channel)   ((present) ? (0x8 | ((channel) & 0x7)) : 0)
#define KPC_OLD_S2C_DMA_CH_NUM(cte)   KPC_OLD_DMA_CH_NUM(cte.s2c_dma_present, cte.s2c_dma_channel_num)
#define KPC_OLD_C2S_DMA_CH_NUM(cte)   KPC_OLD_DMA_CH_NUM(cte.c2s_dma_present, cte.c2s_dma_channel_num)

#define KP_CORE_ID_INVALID      0
#define KP_CORE_ID_I2C          3
#define KP_CORE_ID_SPI          5

struct core_table_entry {
    u16     type;
    u32     offset;
    u32     length;
    bool    s2c_dma_present;
    u8      s2c_dma_channel_num;
    bool    c2s_dma_present;
    u8      c2s_dma_channel_num;
    u8      irq_count;
    u8      irq_base_num;
};

static
void  parse_core_table_entry_v0(struct core_table_entry *cte, const u64 read_val)
{
    cte->type                = ((read_val & 0xFFF0000000000000) >> 52);
    cte->offset              = ((read_val & 0x00000000FFFF0000) >> 16) * 4096;
    cte->length              = ((read_val & 0x0000FFFF00000000) >> 32) * 8;
    cte->s2c_dma_present     = ((read_val & 0x0008000000000000) >> 51);
    cte->s2c_dma_channel_num = ((read_val & 0x0007000000000000) >> 48);
    cte->c2s_dma_present     = ((read_val & 0x0000000000008000) >> 15);
    cte->c2s_dma_channel_num = ((read_val & 0x0000000000007000) >> 12);
    cte->irq_count           = ((read_val & 0x0000000000000C00) >> 10);
    cte->irq_base_num        = ((read_val & 0x00000000000003F8) >>  3);
}

static
void dbg_cte(struct kp2000_device *pcard, struct core_table_entry *cte)
{
    dev_dbg(&pcard->pdev->dev, "CTE: type:%3d  offset:%3d (%3d)  length:%3d (%3d)  s2c:%d  c2s:%d  irq_count:%d  base_irq:%d\n",
        cte->type,
        cte->offset,
        cte->offset / 4096,
        cte->length,
        cte->length / 8,
        (cte->s2c_dma_present ? cte->s2c_dma_channel_num : -1),
        (cte->c2s_dma_present ? cte->c2s_dma_channel_num : -1),
        cte->irq_count,
        cte->irq_base_num
    );
}

static
void parse_core_table_entry(struct core_table_entry *cte, const u64 read_val, const u8 entry_rev)
{
	switch (entry_rev) {
	case 0: parse_core_table_entry_v0(cte, read_val); break;
	default: cte->type = 0; break;
	}
}


int  probe_core_basic(unsigned int core_num, struct kp2000_device *pcard, char *name, const struct core_table_entry cte)
{
    struct mfd_cell  cell = {0};
    struct resource  resources[2] = {0};
    
    struct kpc_core_device_platdata  core_pdata = {
        .card_id           = pcard->card_id,
        .build_version     = pcard->build_version,
        .hardware_revision = pcard->hardware_revision,
        .ssid              = pcard->ssid,
        .ddna              = pcard->ddna,
    };

    dev_dbg(&pcard->pdev->dev, "Found Basic core: type = %02d  dma = %02x / %02x  offset = 0x%x  length = 0x%x (%d regs)\n", cte.type, KPC_OLD_S2C_DMA_CH_NUM(cte), KPC_OLD_C2S_DMA_CH_NUM(cte), cte.offset, cte.length, cte.length / 8);
    
    
    cell.platform_data = &core_pdata;
    cell.pdata_size = sizeof(struct kpc_core_device_platdata);
    cell.name = name;
    cell.id = core_num;
    cell.num_resources = 2;
    
    resources[0].start = cte.offset;
    resources[0].end   = cte.offset + (cte.length - 1);
    resources[0].flags = IORESOURCE_MEM;
    
    resources[1].start = pcard->pdev->irq;
    resources[1].end   = pcard->pdev->irq;
    resources[1].flags = IORESOURCE_IRQ;
    
    cell.resources = resources;
    
    return mfd_add_devices(
        PCARD_TO_DEV(pcard),    // parent
        pcard->card_num * 100,  // id
        &cell,                  // struct mfd_cell *
        1,                      // ndevs
        &pcard->regs_base_resource,
        0,                      // irq_base
        NULL                    // struct irq_domain *
    );
}


struct kpc_uio_device {
    struct list_head list;
    struct kp2000_device *pcard;
    struct device  *dev;
    struct uio_info uioinfo;
    struct core_table_entry cte;
    u16 core_num;
};

static ssize_t  show_attr(struct device *dev, struct device_attribute *attr, char *buf)
{
    struct kpc_uio_device *kudev = dev_get_drvdata(dev);
    
    #define ATTR_NAME_CMP(v)  (strcmp(v, attr->attr.name) == 0)
    if ATTR_NAME_CMP("offset"){
        return scnprintf(buf, PAGE_SIZE, "%u\n", kudev->cte.offset);
    } else if ATTR_NAME_CMP("size"){
        return scnprintf(buf, PAGE_SIZE, "%u\n", kudev->cte.length);
    } else if ATTR_NAME_CMP("type"){
        return scnprintf(buf, PAGE_SIZE, "%u\n", kudev->cte.type);
    }
    else if ATTR_NAME_CMP("s2c_dma"){
        if (kudev->cte.s2c_dma_present){
            return scnprintf(buf, PAGE_SIZE, "%u\n", kudev->cte.s2c_dma_channel_num);
        } else {
            return scnprintf(buf, PAGE_SIZE, "not present\n");
        }
    } else if ATTR_NAME_CMP("c2s_dma"){
        if (kudev->cte.c2s_dma_present){
            return scnprintf(buf, PAGE_SIZE, "%u\n", kudev->cte.c2s_dma_channel_num);
        } else {
            return scnprintf(buf, PAGE_SIZE, "not present\n");
        }
    }
    else if ATTR_NAME_CMP("irq_count"){
        return scnprintf(buf, PAGE_SIZE, "%u\n", kudev->cte.irq_count);
    } else if ATTR_NAME_CMP("irq_base_num"){
        return scnprintf(buf, PAGE_SIZE, "%u\n", kudev->cte.irq_base_num);
    } else if ATTR_NAME_CMP("core_num"){
        return scnprintf(buf, PAGE_SIZE, "%u\n", kudev->core_num);
    } else {
        return 0;
    }
    #undef ATTR_NAME_CMP
}


DEVICE_ATTR(offset,  0444, show_attr, NULL);
DEVICE_ATTR(size,    0444, show_attr, NULL);
DEVICE_ATTR(type,    0444, show_attr, NULL);
DEVICE_ATTR(s2c_dma_ch, 0444, show_attr, NULL);
DEVICE_ATTR(c2s_dma_ch, 0444, show_attr, NULL);
DEVICE_ATTR(s2c_dma, 0444, show_attr, NULL);
DEVICE_ATTR(c2s_dma, 0444, show_attr, NULL);
DEVICE_ATTR(irq_count, 0444, show_attr, NULL);
DEVICE_ATTR(irq_base_num, 0444, show_attr, NULL);
DEVICE_ATTR(core_num, 0444, show_attr, NULL);
struct attribute * kpc_uio_class_attrs[] = {
	&dev_attr_offset.attr,
	&dev_attr_size.attr,
	&dev_attr_type.attr,
	&dev_attr_s2c_dma_ch.attr,
	&dev_attr_c2s_dma_ch.attr,
	&dev_attr_s2c_dma.attr,
	&dev_attr_c2s_dma.attr,
	&dev_attr_irq_count.attr,
	&dev_attr_irq_base_num.attr,
	&dev_attr_core_num.attr,
	NULL,
};


static
int  kp2000_check_uio_irq(struct kp2000_device *pcard, u32 irq_num)
{
    u64 interrupt_active   =  readq(pcard->sysinfo_regs_base + REG_INTERRUPT_ACTIVE);
    u64 interrupt_mask_inv = ~readq(pcard->sysinfo_regs_base + REG_INTERRUPT_MASK);
    u64 irq_check_mask = (1 << irq_num);
    if (interrupt_active & irq_check_mask){ // if it's active (interrupt pending)
        if (interrupt_mask_inv & irq_check_mask){    // and if it's not masked off
            return 1;
        }
    }
    return 0;
}

static
irqreturn_t  kuio_handler(int irq, struct uio_info *uioinfo)
{
    struct kpc_uio_device *kudev = uioinfo->priv;
    if (irq != kudev->pcard->pdev->irq)
        return IRQ_NONE;
    
    if (kp2000_check_uio_irq(kudev->pcard, kudev->cte.irq_base_num)){
        writeq((1 << kudev->cte.irq_base_num), kudev->pcard->sysinfo_regs_base + REG_INTERRUPT_ACTIVE); // Clear the active flag
        return IRQ_HANDLED;
    }
    return IRQ_NONE;
}

static
int kuio_irqcontrol(struct uio_info *uioinfo, s32 irq_on)
{
    struct kpc_uio_device *kudev = uioinfo->priv;
    struct kp2000_device *pcard = kudev->pcard;
    u64 mask;
    
    lock_card(pcard);
    mask = readq(pcard->sysinfo_regs_base + REG_INTERRUPT_MASK);
    if (irq_on){
        mask &= ~(1 << (kudev->cte.irq_base_num));
    } else {
        mask |= (1 << (kudev->cte.irq_base_num));
    }
    writeq(mask, pcard->sysinfo_regs_base + REG_INTERRUPT_MASK);
    unlock_card(pcard);
    
    return 0;
}

int  probe_core_uio(unsigned int core_num, struct kp2000_device *pcard, char *name, const struct core_table_entry cte)
{
    struct kpc_uio_device  *kudev;
    int rv;

    dev_dbg(&pcard->pdev->dev, "Found UIO core:   type = %02d  dma = %02x / %02x  offset = 0x%x  length = 0x%x (%d regs)\n", cte.type, KPC_OLD_S2C_DMA_CH_NUM(cte), KPC_OLD_C2S_DMA_CH_NUM(cte), cte.offset, cte.length, cte.length / 8);
    
    kudev = kzalloc(sizeof(struct kpc_uio_device), GFP_KERNEL);
    if (!kudev){
        dev_err(&pcard->pdev->dev, "probe_core_uio: failed to kzalloc kpc_uio_device\n");
        return -ENOMEM;
    }
    
    INIT_LIST_HEAD(&kudev->list);
    kudev->pcard = pcard;
    kudev->cte = cte;
    kudev->core_num = core_num;
    
    kudev->uioinfo.priv = kudev;
    kudev->uioinfo.name = name;
    kudev->uioinfo.version = "0.0";
    if (cte.irq_count > 0){
        kudev->uioinfo.irq_flags = IRQF_SHARED;
        kudev->uioinfo.irq = pcard->pdev->irq;
        kudev->uioinfo.handler = kuio_handler;
        kudev->uioinfo.irqcontrol = kuio_irqcontrol;
    } else {
        kudev->uioinfo.irq = 0;
    }

    kudev->uioinfo.mem[0].name = "uiomap";
    kudev->uioinfo.mem[0].addr = pci_resource_start(pcard->pdev, REG_BAR) + cte.offset;
    kudev->uioinfo.mem[0].size = (cte.length + PAGE_SIZE-1) & ~(PAGE_SIZE-1); // Round up to nearest PAGE_SIZE boundary
    kudev->uioinfo.mem[0].memtype = UIO_MEM_PHYS;
    
    kudev->dev = device_create(kpc_uio_class, &pcard->pdev->dev, MKDEV(0,0), kudev, "%s.%d.%d.%d", kudev->uioinfo.name, pcard->card_num, cte.type, kudev->core_num);
    if (IS_ERR(kudev->dev)) {
        dev_err(&pcard->pdev->dev, "probe_core_uio device_create failed!\n");
        return -ENODEV;
    }
    dev_set_drvdata(kudev->dev, kudev);
    
    rv = uio_register_device(kudev->dev, &kudev->uioinfo);
    if (rv){
        dev_err(&pcard->pdev->dev, "probe_core_uio failed uio_register_device: %d\n", rv);
        return rv;
    }
    
    list_add_tail(&kudev->list, &pcard->uio_devices_list);
    
    return 0;
}


static int  create_dma_engine_core(struct kp2000_device *pcard, size_t engine_regs_offset, int engine_num, int irq_num)
{
    struct mfd_cell  cell = {0};
    struct resource  resources[2] = {0};
    
    dev_dbg(&pcard->pdev->dev, "create_dma_core(pcard = [%p], engine_regs_offset = %zx, engine_num = %d)\n", pcard, engine_regs_offset, engine_num);
    
    cell.platform_data = NULL;
    cell.pdata_size = 0;
    cell.id = engine_num;
    cell.name = KP_DRIVER_NAME_DMA_CONTROLLER;
    cell.num_resources = 2;
    
    resources[0].start = engine_regs_offset;
    resources[0].end   = engine_regs_offset + (KPC_DMA_ENGINE_SIZE - 1);
    resources[0].flags = IORESOURCE_MEM;
    
    resources[1].start = irq_num;
    resources[1].end   = irq_num;
    resources[1].flags = IORESOURCE_IRQ;
    
    cell.resources = resources;
    
    return mfd_add_devices(
        PCARD_TO_DEV(pcard),    // parent
        pcard->card_num * 100,  // id
        &cell,                  // struct mfd_cell *
        1,                      // ndevs
        &pcard->dma_base_resource,
        0,                      // irq_base
        NULL                    // struct irq_domain *
    );
}

static int  kp2000_setup_dma_controller(struct kp2000_device *pcard)
{
    int err;
    unsigned int i;
    u64 capabilities_reg;
    
    // S2C Engines
    for (i = 0 ; i < 32 ; i++){
        capabilities_reg = readq( pcard->dma_bar_base + KPC_DMA_S2C_BASE_OFFSET + (KPC_DMA_ENGINE_SIZE * i) );
        if (capabilities_reg & ENGINE_CAP_PRESENT_MASK){
            err = create_dma_engine_core(pcard, (KPC_DMA_S2C_BASE_OFFSET + (KPC_DMA_ENGINE_SIZE * i)), i,  pcard->pdev->irq);
            if (err) goto err_out;
        }
    }
    // C2S Engines
    for (i = 0 ; i < 32 ; i++){
        capabilities_reg = readq( pcard->dma_bar_base + KPC_DMA_C2S_BASE_OFFSET + (KPC_DMA_ENGINE_SIZE * i) );
        if (capabilities_reg & ENGINE_CAP_PRESENT_MASK){
            err = create_dma_engine_core(pcard, (KPC_DMA_C2S_BASE_OFFSET + (KPC_DMA_ENGINE_SIZE * i)), 32+i,  pcard->pdev->irq);
            if (err) goto err_out;
        }
    }
    
    return 0;
    
err_out:
    dev_err(&pcard->pdev->dev, "kp2000_setup_dma_controller: failed to add a DMA Engine: %d\n", err);
    return err;
}

int  kp2000_probe_cores(struct kp2000_device *pcard)
{
    int err = 0;
    int i;
    int current_type_id;
    u64 read_val;
    unsigned int highest_core_id = 0;
    struct core_table_entry cte;

    dev_dbg(&pcard->pdev->dev, "kp2000_probe_cores(pcard = %p / %d)\n", pcard, pcard->card_num);
    
    err = kp2000_setup_dma_controller(pcard);
    if (err) return err;
    
    INIT_LIST_HEAD(&pcard->uio_devices_list);
    
    // First, iterate the core table looking for the highest CORE_ID
    for (i = 0 ; i < pcard->core_table_length ; i++){
        read_val = readq(pcard->sysinfo_regs_base + ((pcard->core_table_offset + i) * 8));
        parse_core_table_entry(&cte, read_val, pcard->core_table_rev);
        dbg_cte(pcard, &cte);
        if (cte.type > highest_core_id){
            highest_core_id = cte.type;
        }
        if (cte.type == KP_CORE_ID_INVALID){
            dev_info(&pcard->pdev->dev, "Found Invalid core: %016llx\n", read_val);
        }
    }
    // Then, iterate over the possible core types.
    for (current_type_id = 1 ; current_type_id <= highest_core_id ; current_type_id++){
        unsigned int core_num = 0;
        // Foreach core type, iterate the whole table and instantiate subdevices for each core.
        // Yes, this is O(n*m) but the actual runtime is small enough that it's an acceptable tradeoff.
        for (i = 0 ; i < pcard->core_table_length ; i++){
            read_val = readq(pcard->sysinfo_regs_base + ((pcard->core_table_offset + i) * 8));
            parse_core_table_entry(&cte, read_val, pcard->core_table_rev);
            
            if (cte.type == current_type_id){
                switch (cte.type){
                    case KP_CORE_ID_I2C:
                        err = probe_core_basic(core_num, pcard, KP_DRIVER_NAME_I2C, cte);
                        break;
                    
                    case KP_CORE_ID_SPI:
                        err = probe_core_basic(core_num, pcard, KP_DRIVER_NAME_SPI, cte);
                        break;
                    
                    default:
                        err = probe_core_uio(core_num, pcard, "kpc_uio", cte);
                        break;
                }
                if (err){
                    dev_err(&pcard->pdev->dev, "kp2000_probe_cores: failed to add core %d: %d\n", i, err);
                    return err;
                }
                core_num++;
            }
        }
    }
    
    // Finally, instantiate a UIO device for the core_table.
    cte.type                = 0; // CORE_ID_BOARD_INFO
    cte.offset              = 0; // board info is always at the beginning
    cte.length              = 512*8;
    cte.s2c_dma_present     = false;
    cte.s2c_dma_channel_num = 0;
    cte.c2s_dma_present     = false;
    cte.c2s_dma_channel_num = 0;
    cte.irq_count           = 0;
    cte.irq_base_num        = 0;
    err = probe_core_uio(0, pcard, "kpc_uio", cte);
    if (err){
        dev_err(&pcard->pdev->dev, "kp2000_probe_cores: failed to add board_info core: %d\n", err);
        return err;
    }
    
    return 0;
}

void  kp2000_remove_cores(struct kp2000_device *pcard)
{
    struct list_head *ptr;
    struct list_head *next;
    list_for_each_safe(ptr, next, &pcard->uio_devices_list){
        struct kpc_uio_device *kudev = list_entry(ptr, struct kpc_uio_device, list);
        uio_unregister_device(&kudev->uioinfo);
        device_unregister(kudev->dev);
        list_del(&kudev->list);
        kfree(kudev);
    }
}