// SPDX-License-Identifier: GPL-2.0-or-later
/*
 * Copyright 2015 IBM Corp.
 *
 * Joel Stanley <joel@jms.id.au>
 */

#include <asm/div64.h>
#include <linux/clk.h>
#include <linux/gpio/driver.h>
#include <linux/gpio/aspeed.h>
#include <linux/hashtable.h>
#include <linux/init.h>
#include <linux/io.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/pinctrl/consumer.h>
#include <linux/platform_device.h>
#include <linux/spinlock.h>
#include <linux/string.h>

/*
 * These two headers aren't meant to be used by GPIO drivers. We need
 * them in order to access gpio_chip_hwgpio() which we need to implement
 * the aspeed specific API which allows the coprocessor to request
 * access to some GPIOs and to arbitrate between coprocessor and ARM.
 */
#include <linux/gpio/consumer.h>
#include "gpiolib.h"

struct aspeed_bank_props {
        unsigned int bank;
        u32 input;
        u32 output;
};

struct aspeed_gpio_config {
        unsigned int nr_gpios;
        const struct aspeed_bank_props *props;
};

/*
 * @offset_timer: Maps an offset to an @timer_users index, or zero if disabled
 * @timer_users: Tracks the number of users for each timer
 *
 * The @timer_users has four elements but the first element is unused. This is
 * to simplify accounting and indexing, as a zero value in @offset_timer
 * represents disabled debouncing for the GPIO. Any other value for an element
 * of @offset_timer is used as an index into @timer_users. This behaviour of
 * the zero value aligns with the behaviour of zero built from the timer
 * configuration registers (i.e. debouncing is disabled).
 */
struct aspeed_gpio {
        struct gpio_chip chip;
        struct irq_chip irqc;
        spinlock_t lock;
        void __iomem *base;
        int irq;
        const struct aspeed_gpio_config *config;

        u8 *offset_timer;
        unsigned int timer_users[4];
        struct clk *clk;

        u32 *dcache;
        u8 *cf_copro_bankmap;
};

struct aspeed_gpio_bank {
        uint16_t        val_regs;       /* +0: Rd: read input value, Wr: set write latch
                                         * +4: Rd/Wr: Direction (0=in, 1=out)
                                         */
        uint16_t        rdata_reg;      /*     Rd: read write latch, Wr: <none>  */
        uint16_t        irq_regs;
        uint16_t        debounce_regs;
        uint16_t        tolerance_regs;
        uint16_t        cmdsrc_regs;
        const char      names[4][3];
};

/*
 * Note: The "value" register returns the input value sampled on the
 *       line even when the GPIO is configured as an output. Since
 *       that input goes through synchronizers, writing, then reading
 *       back may not return the written value right away.
 *
 *       The "rdata" register returns the content of the write latch
 *       and thus can be used to read back what was last written
 *       reliably.
 */

static const int debounce_timers[4] = { 0x00, 0x50, 0x54, 0x58 };

static const struct aspeed_gpio_copro_ops *copro_ops;
static void *copro_data;

static const struct aspeed_gpio_bank aspeed_gpio_banks[] = {
        {
                .val_regs = 0x0000,
                .rdata_reg = 0x00c0,
                .irq_regs = 0x0008,
                .debounce_regs = 0x0040,
                .tolerance_regs = 0x001c,
                .cmdsrc_regs = 0x0060,
                .names = { "A", "B", "C", "D" },
        },
        {
                .val_regs = 0x0020,
                .rdata_reg = 0x00c4,
                .irq_regs = 0x0028,
                .debounce_regs = 0x0048,
                .tolerance_regs = 0x003c,
                .cmdsrc_regs = 0x0068,
                .names = { "E", "F", "G", "H" },
        },
        {
                .val_regs = 0x0070,
                .rdata_reg = 0x00c8,
                .irq_regs = 0x0098,
                .debounce_regs = 0x00b0,
                .tolerance_regs = 0x00ac,
                .cmdsrc_regs = 0x0090,
                .names = { "I", "J", "K", "L" },
        },
        {
                .val_regs = 0x0078,
                .rdata_reg = 0x00cc,
                .irq_regs = 0x00e8,
                .debounce_regs = 0x0100,
                .tolerance_regs = 0x00fc,
                .cmdsrc_regs = 0x00e0,
                .names = { "M", "N", "O", "P" },
        },
        {
                .val_regs = 0x0080,
                .rdata_reg = 0x00d0,
                .irq_regs = 0x0118,
                .debounce_regs = 0x0130,
                .tolerance_regs = 0x012c,
                .cmdsrc_regs = 0x0110,
                .names = { "Q", "R", "S", "T" },
        },
        {
                .val_regs = 0x0088,
                .rdata_reg = 0x00d4,
                .irq_regs = 0x0148,
                .debounce_regs = 0x0160,
                .tolerance_regs = 0x015c,
                .cmdsrc_regs = 0x0140,
                .names = { "U", "V", "W", "X" },
        },
        {
                .val_regs = 0x01E0,
                .rdata_reg = 0x00d8,
                .irq_regs = 0x0178,
                .debounce_regs = 0x0190,
                .tolerance_regs = 0x018c,
                .cmdsrc_regs = 0x0170,
                .names = { "Y", "Z", "AA", "AB" },
        },
        {
                .val_regs = 0x01e8,
                .rdata_reg = 0x00dc,
                .irq_regs = 0x01a8,
                .debounce_regs = 0x01c0,
                .tolerance_regs = 0x01bc,
                .cmdsrc_regs = 0x01a0,
                .names = { "AC", "", "", "" },
        },
};

enum aspeed_gpio_reg {
        reg_val,
        reg_rdata,
        reg_dir,
        reg_irq_enable,
        reg_irq_type0,
        reg_irq_type1,
        reg_irq_type2,
        reg_irq_status,
        reg_debounce_sel1,
        reg_debounce_sel2,
        reg_tolerance,
        reg_cmdsrc0,
        reg_cmdsrc1,
};

#define GPIO_VAL_VALUE  0x00
#define GPIO_VAL_DIR    0x04

#define GPIO_IRQ_ENABLE 0x00
#define GPIO_IRQ_TYPE0  0x04
#define GPIO_IRQ_TYPE1  0x08
#define GPIO_IRQ_TYPE2  0x0c
#define GPIO_IRQ_STATUS 0x10

#define GPIO_DEBOUNCE_SEL1 0x00
#define GPIO_DEBOUNCE_SEL2 0x04

#define GPIO_CMDSRC_0   0x00
#define GPIO_CMDSRC_1   0x04
#define  GPIO_CMDSRC_ARM                0
#define  GPIO_CMDSRC_LPC                1
#define  GPIO_CMDSRC_COLDFIRE           2
#define  GPIO_CMDSRC_RESERVED           3

/* This will be resolved at compile time */
static inline void __iomem *bank_reg(struct aspeed_gpio *gpio,
                                     const struct aspeed_gpio_bank *bank,
                                     const enum aspeed_gpio_reg reg)
{
        switch (reg) {
        case reg_val:
                return gpio->base + bank->val_regs + GPIO_VAL_VALUE;
        case reg_rdata:
                return gpio->base + bank->rdata_reg;
        case reg_dir:
                return gpio->base + bank->val_regs + GPIO_VAL_DIR;
        case reg_irq_enable:
                return gpio->base + bank->irq_regs + GPIO_IRQ_ENABLE;
        case reg_irq_type0:
                return gpio->base + bank->irq_regs + GPIO_IRQ_TYPE0;
        case reg_irq_type1:
                return gpio->base + bank->irq_regs + GPIO_IRQ_TYPE1;
        case reg_irq_type2:
                return gpio->base + bank->irq_regs + GPIO_IRQ_TYPE2;
        case reg_irq_status:
                return gpio->base + bank->irq_regs + GPIO_IRQ_STATUS;
        case reg_debounce_sel1:
                return gpio->base + bank->debounce_regs + GPIO_DEBOUNCE_SEL1;
        case reg_debounce_sel2:
                return gpio->base + bank->debounce_regs + GPIO_DEBOUNCE_SEL2;
        case reg_tolerance:
                return gpio->base + bank->tolerance_regs;
        case reg_cmdsrc0:
                return gpio->base + bank->cmdsrc_regs + GPIO_CMDSRC_0;
        case reg_cmdsrc1:
                return gpio->base + bank->cmdsrc_regs + GPIO_CMDSRC_1;
        }
        BUG();
}

#define GPIO_BANK(x)    ((x) >> 5)
#define GPIO_OFFSET(x)  ((x) & 0x1f)
#define GPIO_BIT(x)     BIT(GPIO_OFFSET(x))

#define _GPIO_SET_DEBOUNCE(t, o, i) ((!!((t) & BIT(i))) << GPIO_OFFSET(o))
#define GPIO_SET_DEBOUNCE1(t, o) _GPIO_SET_DEBOUNCE(t, o, 1)
#define GPIO_SET_DEBOUNCE2(t, o) _GPIO_SET_DEBOUNCE(t, o, 0)

static const struct aspeed_gpio_bank *to_bank(unsigned int offset)
{
        unsigned int bank = GPIO_BANK(offset);

        WARN_ON(bank >= ARRAY_SIZE(aspeed_gpio_banks));
        return &aspeed_gpio_banks[bank];
}

static inline bool is_bank_props_sentinel(const struct aspeed_bank_props *props)
{
        return !(props->input || props->output);
}

static inline const struct aspeed_bank_props *find_bank_props(
                struct aspeed_gpio *gpio, unsigned int offset)
{
        const struct aspeed_bank_props *props = gpio->config->props;

        while (!is_bank_props_sentinel(props)) {
                if (props->bank == GPIO_BANK(offset))
                        return props;
                props++;
        }

        return NULL;
}

static inline bool have_gpio(struct aspeed_gpio *gpio, unsigned int offset)
{
        const struct aspeed_bank_props *props = find_bank_props(gpio, offset);
        const struct aspeed_gpio_bank *bank = to_bank(offset);
        unsigned int group = GPIO_OFFSET(offset) / 8;

        return bank->names[group][0] != '\0' &&
                (!props || ((props->input | props->output) & GPIO_BIT(offset)));
}

static inline bool have_input(struct aspeed_gpio *gpio, unsigned int offset)
{
        const struct aspeed_bank_props *props = find_bank_props(gpio, offset);

        return !props || (props->input & GPIO_BIT(offset));
}

#define have_irq(g, o) have_input((g), (o))
#define have_debounce(g, o) have_input((g), (o))

static inline bool have_output(struct aspeed_gpio *gpio, unsigned int offset)
{
        const struct aspeed_bank_props *props = find_bank_props(gpio, offset);

        return !props || (props->output & GPIO_BIT(offset));
}

static void aspeed_gpio_change_cmd_source(struct aspeed_gpio *gpio,
                                          const struct aspeed_gpio_bank *bank,
                                          int bindex, int cmdsrc)
{
        void __iomem *c0 = bank_reg(gpio, bank, reg_cmdsrc0);
        void __iomem *c1 = bank_reg(gpio, bank, reg_cmdsrc1);
        u32 bit, reg;

        /*
         * Each register controls 4 banks, so take the bottom 2
         * bits of the bank index, and use them to select the
         * right control bit (0, 8, 16 or 24).
         */
        bit = BIT((bindex & 3) << 3);

        /* Source 1 first to avoid illegal 11 combination */
        reg = ioread32(c1);
        if (cmdsrc & 2)
                reg |= bit;
        else
                reg &= ~bit;
        iowrite32(reg, c1);

        /* Then Source 0 */
        reg = ioread32(c0);
        if (cmdsrc & 1)
                reg |= bit;
        else
                reg &= ~bit;
        iowrite32(reg, c0);
}

static bool aspeed_gpio_copro_request(struct aspeed_gpio *gpio,
                                      unsigned int offset)
{
        const struct aspeed_gpio_bank *bank = to_bank(offset);

        if (!copro_ops || !gpio->cf_copro_bankmap)
                return false;
        if (!gpio->cf_copro_bankmap[offset >> 3])
                return false;
        if (!copro_ops->request_access)
                return false;

        /* Pause the coprocessor */
        copro_ops->request_access(copro_data);

        /* Change command source back to ARM */
        aspeed_gpio_change_cmd_source(gpio, bank, offset >> 3, GPIO_CMDSRC_ARM);

        /* Update cache */
        gpio->dcache[GPIO_BANK(offset)] = ioread32(bank_reg(gpio, bank, reg_rdata));

        return true;
}

static void aspeed_gpio_copro_release(struct aspeed_gpio *gpio,
                                      unsigned int offset)
{
        const struct aspeed_gpio_bank *bank = to_bank(offset);

        if (!copro_ops || !gpio->cf_copro_bankmap)
                return;
        if (!gpio->cf_copro_bankmap[offset >> 3])
                return;
        if (!copro_ops->release_access)
                return;

        /* Change command source back to ColdFire */
        aspeed_gpio_change_cmd_source(gpio, bank, offset >> 3,
                                      GPIO_CMDSRC_COLDFIRE);

        /* Restart the coprocessor */
        copro_ops->release_access(copro_data);
}

static int aspeed_gpio_get(struct gpio_chip *gc, unsigned int offset)
{
        struct aspeed_gpio *gpio = gpiochip_get_data(gc);
        const struct aspeed_gpio_bank *bank = to_bank(offset);

        return !!(ioread32(bank_reg(gpio, bank, reg_val)) & GPIO_BIT(offset));
}

static void __aspeed_gpio_set(struct gpio_chip *gc, unsigned int offset,
                              int val)
{
        struct aspeed_gpio *gpio = gpiochip_get_data(gc);
        const struct aspeed_gpio_bank *bank = to_bank(offset);
        void __iomem *addr;
        u32 reg;

        addr = bank_reg(gpio, bank, reg_val);
        reg = gpio->dcache[GPIO_BANK(offset)];

        if (val)
                reg |= GPIO_BIT(offset);
        else
                reg &= ~GPIO_BIT(offset);
        gpio->dcache[GPIO_BANK(offset)] = reg;

        iowrite32(reg, addr);
}

static void aspeed_gpio_set(struct gpio_chip *gc, unsigned int offset,
                            int val)
{
        struct aspeed_gpio *gpio = gpiochip_get_data(gc);
        unsigned long flags;
        bool copro;

        spin_lock_irqsave(&gpio->lock, flags);
        copro = aspeed_gpio_copro_request(gpio, offset);

        __aspeed_gpio_set(gc, offset, val);

        if (copro)
                aspeed_gpio_copro_release(gpio, offset);
        spin_unlock_irqrestore(&gpio->lock, flags);
}

static int aspeed_gpio_dir_in(struct gpio_chip *gc, unsigned int offset)
{
        struct aspeed_gpio *gpio = gpiochip_get_data(gc);
        const struct aspeed_gpio_bank *bank = to_bank(offset);
        void __iomem *addr = bank_reg(gpio, bank, reg_dir);
        unsigned long flags;
        bool copro;
        u32 reg;

        if (!have_input(gpio, offset))
                return -ENOTSUPP;

        spin_lock_irqsave(&gpio->lock, flags);

        reg = ioread32(addr);
        reg &= ~GPIO_BIT(offset);

        copro = aspeed_gpio_copro_request(gpio, offset);
        iowrite32(reg, addr);
        if (copro)
                aspeed_gpio_copro_release(gpio, offset);

        spin_unlock_irqrestore(&gpio->lock, flags);

        return 0;
}

static int aspeed_gpio_dir_out(struct gpio_chip *gc,
                               unsigned int offset, int val)
{
        struct aspeed_gpio *gpio = gpiochip_get_data(gc);
        const struct aspeed_gpio_bank *bank = to_bank(offset);
        void __iomem *addr = bank_reg(gpio, bank, reg_dir);
        unsigned long flags;
        bool copro;
        u32 reg;

        if (!have_output(gpio, offset))
                return -ENOTSUPP;

        spin_lock_irqsave(&gpio->lock, flags);

        reg = ioread32(addr);
        reg |= GPIO_BIT(offset);

        copro = aspeed_gpio_copro_request(gpio, offset);
        __aspeed_gpio_set(gc, offset, val);
        iowrite32(reg, addr);

        if (copro)
                aspeed_gpio_copro_release(gpio, offset);
        spin_unlock_irqrestore(&gpio->lock, flags);

        return 0;
}

static int aspeed_gpio_get_direction(struct gpio_chip *gc, unsigned int offset)
{
        struct aspeed_gpio *gpio = gpiochip_get_data(gc);
        const struct aspeed_gpio_bank *bank = to_bank(offset);
        unsigned long flags;
        u32 val;

        if (!have_input(gpio, offset))
                return GPIO_LINE_DIRECTION_OUT;

        if (!have_output(gpio, offset))
                return GPIO_LINE_DIRECTION_IN;

        spin_lock_irqsave(&gpio->lock, flags);

        val = ioread32(bank_reg(gpio, bank, reg_dir)) & GPIO_BIT(offset);

        spin_unlock_irqrestore(&gpio->lock, flags);

        return val ? GPIO_LINE_DIRECTION_OUT : GPIO_LINE_DIRECTION_IN;
}

static inline int irqd_to_aspeed_gpio_data(struct irq_data *d,
                                           struct aspeed_gpio **gpio,
                                           const struct aspeed_gpio_bank **bank,
                                           u32 *bit, int *offset)
{
        struct aspeed_gpio *internal;

        *offset = irqd_to_hwirq(d);

        internal = irq_data_get_irq_chip_data(d);

        /* This might be a bit of a questionable place to check */
        if (!have_irq(internal, *offset))
                return -ENOTSUPP;

        *gpio = internal;
        *bank = to_bank(*offset);
        *bit = GPIO_BIT(*offset);

        return 0;
}

static void aspeed_gpio_irq_ack(struct irq_data *d)
{
        const struct aspeed_gpio_bank *bank;
        struct aspeed_gpio *gpio;
        unsigned long flags;
        void __iomem *status_addr;
        int rc, offset;
        bool copro;
        u32 bit;

        rc = irqd_to_aspeed_gpio_data(d, &gpio, &bank, &bit, &offset);
        if (rc)
                return;

        status_addr = bank_reg(gpio, bank, reg_irq_status);

        spin_lock_irqsave(&gpio->lock, flags);
        copro = aspeed_gpio_copro_request(gpio, offset);

        iowrite32(bit, status_addr);

        if (copro)
                aspeed_gpio_copro_release(gpio, offset);
        spin_unlock_irqrestore(&gpio->lock, flags);
}

static void aspeed_gpio_irq_set_mask(struct irq_data *d, bool set)
{
        const struct aspeed_gpio_bank *bank;
        struct aspeed_gpio *gpio;
        unsigned long flags;
        u32 reg, bit;
        void __iomem *addr;
        int rc, offset;
        bool copro;

        rc = irqd_to_aspeed_gpio_data(d, &gpio, &bank, &bit, &offset);
        if (rc)
                return;

        addr = bank_reg(gpio, bank, reg_irq_enable);

        spin_lock_irqsave(&gpio->lock, flags);
        copro = aspeed_gpio_copro_request(gpio, offset);

        reg = ioread32(addr);
        if (set)
                reg |= bit;
        else
                reg &= ~bit;
        iowrite32(reg, addr);

        if (copro)
                aspeed_gpio_copro_release(gpio, offset);
        spin_unlock_irqrestore(&gpio->lock, flags);
}

static void aspeed_gpio_irq_mask(struct irq_data *d)
{
        aspeed_gpio_irq_set_mask(d, false);
}

static void aspeed_gpio_irq_unmask(struct irq_data *d)
{
        aspeed_gpio_irq_set_mask(d, true);
}

static int aspeed_gpio_set_type(struct irq_data *d, unsigned int type)
{
        u32 type0 = 0;
        u32 type1 = 0;
        u32 type2 = 0;
        u32 bit, reg;
        const struct aspeed_gpio_bank *bank;
        irq_flow_handler_t handler;
        struct aspeed_gpio *gpio;
        unsigned long flags;
        void __iomem *addr;
        int rc, offset;
        bool copro;

        rc = irqd_to_aspeed_gpio_data(d, &gpio, &bank, &bit, &offset);
        if (rc)
                return -EINVAL;

        switch (type & IRQ_TYPE_SENSE_MASK) {
        case IRQ_TYPE_EDGE_BOTH:
                type2 |= bit;
                fallthrough;
        case IRQ_TYPE_EDGE_RISING:
                type0 |= bit;
                fallthrough;
        case IRQ_TYPE_EDGE_FALLING:
                handler = handle_edge_irq;
                break;
        case IRQ_TYPE_LEVEL_HIGH:
                type0 |= bit;
                fallthrough;
        case IRQ_TYPE_LEVEL_LOW:
                type1 |= bit;
                handler = handle_level_irq;
                break;
        default:
                return -EINVAL;
        }

        spin_lock_irqsave(&gpio->lock, flags);
        copro = aspeed_gpio_copro_request(gpio, offset);

        addr = bank_reg(gpio, bank, reg_irq_type0);
        reg = ioread32(addr);
        reg = (reg & ~bit) | type0;
        iowrite32(reg, addr);

        addr = bank_reg(gpio, bank, reg_irq_type1);
        reg = ioread32(addr);
        reg = (reg & ~bit) | type1;
        iowrite32(reg, addr);

        addr = bank_reg(gpio, bank, reg_irq_type2);
        reg = ioread32(addr);
        reg = (reg & ~bit) | type2;
        iowrite32(reg, addr);

        if (copro)
                aspeed_gpio_copro_release(gpio, offset);
        spin_unlock_irqrestore(&gpio->lock, flags);

        irq_set_handler_locked(d, handler);

        return 0;
}

static void aspeed_gpio_irq_handler(struct irq_desc *desc)
{
        struct gpio_chip *gc = irq_desc_get_handler_data(desc);
        struct irq_chip *ic = irq_desc_get_chip(desc);
        struct aspeed_gpio *data = gpiochip_get_data(gc);
        unsigned int i, p, banks;
        unsigned long reg;
        struct aspeed_gpio *gpio = gpiochip_get_data(gc);

        chained_irq_enter(ic, desc);

        banks = DIV_ROUND_UP(gpio->chip.ngpio, 32);
        for (i = 0; i < banks; i++) {
                const struct aspeed_gpio_bank *bank = &aspeed_gpio_banks[i];

                reg = ioread32(bank_reg(data, bank, reg_irq_status));

                for_each_set_bit(p, &reg, 32)
                        generic_handle_domain_irq(gc->irq.domain, i * 32 + p);
        }

        chained_irq_exit(ic, desc);
}

static void aspeed_init_irq_valid_mask(struct gpio_chip *gc,
                                       unsigned long *valid_mask,
                                       unsigned int ngpios)
{
        struct aspeed_gpio *gpio = gpiochip_get_data(gc);
        const struct aspeed_bank_props *props = gpio->config->props;

        while (!is_bank_props_sentinel(props)) {
                unsigned int offset;
                const unsigned long int input = props->input;

                /* Pretty crummy approach, but similar to GPIO core */
                for_each_clear_bit(offset, &input, 32) {
                        unsigned int i = props->bank * 32 + offset;

                        if (i >= gpio->chip.ngpio)
                                break;

                        clear_bit(i, valid_mask);
                }

                props++;
        }
}

static int aspeed_gpio_reset_tolerance(struct gpio_chip *chip,
                                        unsigned int offset, bool enable)
{
        struct aspeed_gpio *gpio = gpiochip_get_data(chip);
        unsigned long flags;
        void __iomem *treg;
        bool copro;
        u32 val;

        treg = bank_reg(gpio, to_bank(offset), reg_tolerance);

        spin_lock_irqsave(&gpio->lock, flags);
        copro = aspeed_gpio_copro_request(gpio, offset);

        val = readl(treg);

        if (enable)
                val |= GPIO_BIT(offset);
        else
                val &= ~GPIO_BIT(offset);

        writel(val, treg);

        if (copro)
                aspeed_gpio_copro_release(gpio, offset);
        spin_unlock_irqrestore(&gpio->lock, flags);

        return 0;
}

static int aspeed_gpio_request(struct gpio_chip *chip, unsigned int offset)
{
        if (!have_gpio(gpiochip_get_data(chip), offset))
                return -ENODEV;

        return pinctrl_gpio_request(chip->base + offset);
}

static void aspeed_gpio_free(struct gpio_chip *chip, unsigned int offset)
{
        pinctrl_gpio_free(chip->base + offset);
}

static int usecs_to_cycles(struct aspeed_gpio *gpio, unsigned long usecs,
                u32 *cycles)
{
        u64 rate;
        u64 n;
        u32 r;

        rate = clk_get_rate(gpio->clk);
        if (!rate)
                return -ENOTSUPP;

        n = rate * usecs;
        r = do_div(n, 1000000);

        if (n >= U32_MAX)
                return -ERANGE;

        /* At least as long as the requested time */
        *cycles = n + (!!r);

        return 0;
}

/* Call under gpio->lock */
static int register_allocated_timer(struct aspeed_gpio *gpio,
                unsigned int offset, unsigned int timer)
{
        if (WARN(gpio->offset_timer[offset] != 0,
                                "Offset %d already allocated timer %d\n",
                                offset, gpio->offset_timer[offset]))
                return -EINVAL;

        if (WARN(gpio->timer_users[timer] == UINT_MAX,
                                "Timer user count would overflow\n"))
                return -EPERM;

        gpio->offset_timer[offset] = timer;
        gpio->timer_users[timer]++;

        return 0;
}

/* Call under gpio->lock */
static int unregister_allocated_timer(struct aspeed_gpio *gpio,
                unsigned int offset)
{
        if (WARN(gpio->offset_timer[offset] == 0,
                                "No timer allocated to offset %d\n", offset))
                return -EINVAL;

        if (WARN(gpio->timer_users[gpio->offset_timer[offset]] == 0,
                                "No users recorded for timer %d\n",
                                gpio->offset_timer[offset]))
                return -EINVAL;

        gpio->timer_users[gpio->offset_timer[offset]]--;
        gpio->offset_timer[offset] = 0;

        return 0;
}

/* Call under gpio->lock */
static inline bool timer_allocation_registered(struct aspeed_gpio *gpio,
                unsigned int offset)
{
        return gpio->offset_timer[offset] > 0;
}

/* Call under gpio->lock */
static void configure_timer(struct aspeed_gpio *gpio, unsigned int offset,
                unsigned int timer)
{
        const struct aspeed_gpio_bank *bank = to_bank(offset);
        const u32 mask = GPIO_BIT(offset);
        void __iomem *addr;
        u32 val;

        /* Note: Debounce timer isn't under control of the command
         * source registers, so no need to sync with the coprocessor
         */
        addr = bank_reg(gpio, bank, reg_debounce_sel1);
        val = ioread32(addr);
        iowrite32((val & ~mask) | GPIO_SET_DEBOUNCE1(timer, offset), addr);

        addr = bank_reg(gpio, bank, reg_debounce_sel2);
        val = ioread32(addr);
        iowrite32((val & ~mask) | GPIO_SET_DEBOUNCE2(timer, offset), addr);
}

static int enable_debounce(struct gpio_chip *chip, unsigned int offset,
                                    unsigned long usecs)
{
        struct aspeed_gpio *gpio = gpiochip_get_data(chip);
        u32 requested_cycles;
        unsigned long flags;
        int rc;
        int i;

        if (!gpio->clk)
                return -EINVAL;

        rc = usecs_to_cycles(gpio, usecs, &requested_cycles);
        if (rc < 0) {
                dev_warn(chip->parent, "Failed to convert %luus to cycles at %luHz: %d\n",
                                usecs, clk_get_rate(gpio->clk), rc);
                return rc;
        }

        spin_lock_irqsave(&gpio->lock, flags);

        if (timer_allocation_registered(gpio, offset)) {
                rc = unregister_allocated_timer(gpio, offset);
                if (rc < 0)
                        goto out;
        }

        /* Try to find a timer already configured for the debounce period */
        for (i = 1; i < ARRAY_SIZE(debounce_timers); i++) {
                u32 cycles;

                cycles = ioread32(gpio->base + debounce_timers[i]);
                if (requested_cycles == cycles)
                        break;
        }

        if (i == ARRAY_SIZE(debounce_timers)) {
                int j;

                /*
                 * As there are no timers configured for the requested debounce
                 * period, find an unused timer instead
                 */
                for (j = 1; j < ARRAY_SIZE(gpio->timer_users); j++) {
                        if (gpio->timer_users[j] == 0)
                                break;
                }

                if (j == ARRAY_SIZE(gpio->timer_users)) {
                        dev_warn(chip->parent,
                                        "Debounce timers exhausted, cannot debounce for period %luus\n",
                                        usecs);

                        rc = -EPERM;

                        /*
                         * We already adjusted the accounting to remove @offset
                         * as a user of its previous timer, so also configure
                         * the hardware so @offset has timers disabled for
                         * consistency.
                         */
                        configure_timer(gpio, offset, 0);
                        goto out;
                }

                i = j;

                iowrite32(requested_cycles, gpio->base + debounce_timers[i]);
        }

        if (WARN(i == 0, "Cannot register index of disabled timer\n")) {
                rc = -EINVAL;
                goto out;
        }

        register_allocated_timer(gpio, offset, i);
        configure_timer(gpio, offset, i);

out:
        spin_unlock_irqrestore(&gpio->lock, flags);

        return rc;
}

static int disable_debounce(struct gpio_chip *chip, unsigned int offset)
{
        struct aspeed_gpio *gpio = gpiochip_get_data(chip);
        unsigned long flags;
        int rc;

        spin_lock_irqsave(&gpio->lock, flags);

        rc = unregister_allocated_timer(gpio, offset);
        if (!rc)
                configure_timer(gpio, offset, 0);

        spin_unlock_irqrestore(&gpio->lock, flags);

        return rc;
}

static int set_debounce(struct gpio_chip *chip, unsigned int offset,
                                    unsigned long usecs)
{
        struct aspeed_gpio *gpio = gpiochip_get_data(chip);

        if (!have_debounce(gpio, offset))
                return -ENOTSUPP;

        if (usecs)
                return enable_debounce(chip, offset, usecs);

        return disable_debounce(chip, offset);
}

static int aspeed_gpio_set_config(struct gpio_chip *chip, unsigned int offset,
                                  unsigned long config)
{
        unsigned long param = pinconf_to_config_param(config);
        u32 arg = pinconf_to_config_argument(config);

        if (param == PIN_CONFIG_INPUT_DEBOUNCE)
                return set_debounce(chip, offset, arg);
        else if (param == PIN_CONFIG_BIAS_DISABLE ||
                        param == PIN_CONFIG_BIAS_PULL_DOWN ||
                        param == PIN_CONFIG_DRIVE_STRENGTH)
                return pinctrl_gpio_set_config(offset, config);
        else if (param == PIN_CONFIG_DRIVE_OPEN_DRAIN ||
                        param == PIN_CONFIG_DRIVE_OPEN_SOURCE)
                /* Return -ENOTSUPP to trigger emulation, as per datasheet */
                return -ENOTSUPP;
        else if (param == PIN_CONFIG_PERSIST_STATE)
                return aspeed_gpio_reset_tolerance(chip, offset, arg);

        return -ENOTSUPP;
}

/**
 * aspeed_gpio_copro_set_ops - Sets the callbacks used for handshaking with
 *                             the coprocessor for shared GPIO banks
 * @ops: The callbacks
 * @data: Pointer passed back to the callbacks
 */
int aspeed_gpio_copro_set_ops(const struct aspeed_gpio_copro_ops *ops, void *data)
{
        copro_data = data;
        copro_ops = ops;

        return 0;
}
EXPORT_SYMBOL_GPL(aspeed_gpio_copro_set_ops);

/**
 * aspeed_gpio_copro_grab_gpio - Mark a GPIO used by the coprocessor. The entire
 *                               bank gets marked and any access from the ARM will
 *                               result in handshaking via callbacks.
 * @desc: The GPIO to be marked
 * @vreg_offset: If non-NULL, returns the value register offset in the GPIO space
 * @dreg_offset: If non-NULL, returns the data latch register offset in the GPIO space
 * @bit: If non-NULL, returns the bit number of the GPIO in the registers
 */

int aspeed_gpio_copro_grab_gpio(struct gpio_desc *desc,
                                u16 *vreg_offset, u16 *dreg_offset, u8 *bit)
{
        struct gpio_chip *chip = gpiod_to_chip(desc);
        struct aspeed_gpio *gpio = gpiochip_get_data(chip);
        int rc = 0, bindex, offset = gpio_chip_hwgpio(desc);
        const struct aspeed_gpio_bank *bank = to_bank(offset);
        unsigned long flags;

        if (!gpio->cf_copro_bankmap)
                gpio->cf_copro_bankmap = kzalloc(gpio->chip.ngpio >> 3, GFP_KERNEL);
        if (!gpio->cf_copro_bankmap)
                return -ENOMEM;
        if (offset < 0 || offset > gpio->chip.ngpio)
                return -EINVAL;
        bindex = offset >> 3;

        spin_lock_irqsave(&gpio->lock, flags);

        /* Sanity check, this shouldn't happen */
        if (gpio->cf_copro_bankmap[bindex] == 0xff) {
                rc = -EIO;
                goto bail;
        }
        gpio->cf_copro_bankmap[bindex]++;

        /* Switch command source */
        if (gpio->cf_copro_bankmap[bindex] == 1)
                aspeed_gpio_change_cmd_source(gpio, bank, bindex,
                                              GPIO_CMDSRC_COLDFIRE);

        if (vreg_offset)
                *vreg_offset = bank->val_regs;
        if (dreg_offset)
                *dreg_offset = bank->rdata_reg;
        if (bit)
                *bit = GPIO_OFFSET(offset);
 bail:
        spin_unlock_irqrestore(&gpio->lock, flags);
        return rc;
}
EXPORT_SYMBOL_GPL(aspeed_gpio_copro_grab_gpio);

/**
 * aspeed_gpio_copro_release_gpio - Unmark a GPIO used by the coprocessor.
 * @desc: The GPIO to be marked
 */
int aspeed_gpio_copro_release_gpio(struct gpio_desc *desc)
{
        struct gpio_chip *chip = gpiod_to_chip(desc);
        struct aspeed_gpio *gpio = gpiochip_get_data(chip);
        int rc = 0, bindex, offset = gpio_chip_hwgpio(desc);
        const struct aspeed_gpio_bank *bank = to_bank(offset);
        unsigned long flags;

        if (!gpio->cf_copro_bankmap)
                return -ENXIO;

        if (offset < 0 || offset > gpio->chip.ngpio)
                return -EINVAL;
        bindex = offset >> 3;

        spin_lock_irqsave(&gpio->lock, flags);

        /* Sanity check, this shouldn't happen */
        if (gpio->cf_copro_bankmap[bindex] == 0) {
                rc = -EIO;
                goto bail;
        }
        gpio->cf_copro_bankmap[bindex]--;

        /* Switch command source */
        if (gpio->cf_copro_bankmap[bindex] == 0)
                aspeed_gpio_change_cmd_source(gpio, bank, bindex,
                                              GPIO_CMDSRC_ARM);
 bail:
        spin_unlock_irqrestore(&gpio->lock, flags);
        return rc;
}
EXPORT_SYMBOL_GPL(aspeed_gpio_copro_release_gpio);

/*
 * Any banks not specified in a struct aspeed_bank_props array are assumed to
 * have the properties:
 *
 *     { .input = 0xffffffff, .output = 0xffffffff }
 */

static const struct aspeed_bank_props ast2400_bank_props[] = {
        /*     input      output   */
        { 5, 0xffffffff, 0x0000ffff }, /* U/V/W/X */
        { 6, 0x0000000f, 0x0fffff0f }, /* Y/Z/AA/AB, two 4-GPIO holes */
        { },
};

static const struct aspeed_gpio_config ast2400_config =
        /* 220 for simplicity, really 216 with two 4-GPIO holes, four at end */
        { .nr_gpios = 220, .props = ast2400_bank_props, };

static const struct aspeed_bank_props ast2500_bank_props[] = {
        /*     input      output   */
        { 5, 0xffffffff, 0x0000ffff }, /* U/V/W/X */
        { 6, 0x0fffffff, 0x0fffffff }, /* Y/Z/AA/AB, 4-GPIO hole */
        { 7, 0x000000ff, 0x000000ff }, /* AC */
        { },
};

static const struct aspeed_gpio_config ast2500_config =
        /* 232 for simplicity, actual number is 228 (4-GPIO hole in GPIOAB) */
        { .nr_gpios = 232, .props = ast2500_bank_props, };

static const struct aspeed_bank_props ast2600_bank_props[] = {
        /*     input      output   */
        {4, 0xffffffff,  0x00ffffff}, /* Q/R/S/T */
        {5, 0xffffffff,  0xffffff00}, /* U/V/W/X */
        {6, 0x0000ffff,  0x0000ffff}, /* Y/Z */
        { },
};

static const struct aspeed_gpio_config ast2600_config =
        /*
         * ast2600 has two controllers one with 208 GPIOs and one with 36 GPIOs.
         * We expect ngpio being set in the device tree and this is a fallback
         * option.
         */
        { .nr_gpios = 208, .props = ast2600_bank_props, };

static const struct of_device_id aspeed_gpio_of_table[] = {
        { .compatible = "aspeed,ast2400-gpio", .data = &ast2400_config, },
        { .compatible = "aspeed,ast2500-gpio", .data = &ast2500_config, },
        { .compatible = "aspeed,ast2600-gpio", .data = &ast2600_config, },
        {}
};
MODULE_DEVICE_TABLE(of, aspeed_gpio_of_table);

static int __init aspeed_gpio_probe(struct platform_device *pdev)
{
        const struct of_device_id *gpio_id;
        struct aspeed_gpio *gpio;
        int rc, i, banks, err;
        u32 ngpio;

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

        gpio->base = devm_platform_ioremap_resource(pdev, 0);
        if (IS_ERR(gpio->base))
                return PTR_ERR(gpio->base);

        spin_lock_init(&gpio->lock);

        gpio_id = of_match_node(aspeed_gpio_of_table, pdev->dev.of_node);
        if (!gpio_id)
                return -EINVAL;

        gpio->clk = of_clk_get(pdev->dev.of_node, 0);
        if (IS_ERR(gpio->clk)) {
                dev_warn(&pdev->dev,
                                "Failed to get clock from devicetree, debouncing disabled\n");
                gpio->clk = NULL;
        }

        gpio->config = gpio_id->data;

        gpio->chip.parent = &pdev->dev;
        err = of_property_read_u32(pdev->dev.of_node, "ngpios", &ngpio);
        gpio->chip.ngpio = (u16) ngpio;
        if (err)
                gpio->chip.ngpio = gpio->config->nr_gpios;
        gpio->chip.direction_input = aspeed_gpio_dir_in;
        gpio->chip.direction_output = aspeed_gpio_dir_out;
        gpio->chip.get_direction = aspeed_gpio_get_direction;
        gpio->chip.request = aspeed_gpio_request;
        gpio->chip.free = aspeed_gpio_free;
        gpio->chip.get = aspeed_gpio_get;
        gpio->chip.set = aspeed_gpio_set;
        gpio->chip.set_config = aspeed_gpio_set_config;
        gpio->chip.label = dev_name(&pdev->dev);
        gpio->chip.base = -1;

        /* Allocate a cache of the output registers */
        banks = DIV_ROUND_UP(gpio->chip.ngpio, 32);
        gpio->dcache = devm_kcalloc(&pdev->dev,
                                    banks, sizeof(u32), GFP_KERNEL);
        if (!gpio->dcache)
                return -ENOMEM;

        /*
         * Populate it with initial values read from the HW and switch
         * all command sources to the ARM by default
         */
        for (i = 0; i < banks; i++) {
                const struct aspeed_gpio_bank *bank = &aspeed_gpio_banks[i];
                void __iomem *addr = bank_reg(gpio, bank, reg_rdata);
                gpio->dcache[i] = ioread32(addr);
                aspeed_gpio_change_cmd_source(gpio, bank, 0, GPIO_CMDSRC_ARM);
                aspeed_gpio_change_cmd_source(gpio, bank, 1, GPIO_CMDSRC_ARM);
                aspeed_gpio_change_cmd_source(gpio, bank, 2, GPIO_CMDSRC_ARM);
                aspeed_gpio_change_cmd_source(gpio, bank, 3, GPIO_CMDSRC_ARM);
        }

        /* Optionally set up an irqchip if there is an IRQ */
        rc = platform_get_irq(pdev, 0);
        if (rc > 0) {
                struct gpio_irq_chip *girq;

                gpio->irq = rc;
                girq = &gpio->chip.irq;
                girq->chip = &gpio->irqc;
                girq->chip->name = dev_name(&pdev->dev);
                girq->chip->irq_ack = aspeed_gpio_irq_ack;
                girq->chip->irq_mask = aspeed_gpio_irq_mask;
                girq->chip->irq_unmask = aspeed_gpio_irq_unmask;
                girq->chip->irq_set_type = aspeed_gpio_set_type;
                girq->parent_handler = aspeed_gpio_irq_handler;
                girq->num_parents = 1;
                girq->parents = devm_kcalloc(&pdev->dev, 1,
                                             sizeof(*girq->parents),
                                             GFP_KERNEL);
                if (!girq->parents)
                        return -ENOMEM;
                girq->parents[0] = gpio->irq;
                girq->default_type = IRQ_TYPE_NONE;
                girq->handler = handle_bad_irq;
                girq->init_valid_mask = aspeed_init_irq_valid_mask;
        }

        gpio->offset_timer =
                devm_kzalloc(&pdev->dev, gpio->chip.ngpio, GFP_KERNEL);
        if (!gpio->offset_timer)
                return -ENOMEM;

        rc = devm_gpiochip_add_data(&pdev->dev, &gpio->chip, gpio);
        if (rc < 0)
                return rc;

        return 0;
}

static struct platform_driver aspeed_gpio_driver = {
        .driver = {
                .name = KBUILD_MODNAME,
                .of_match_table = aspeed_gpio_of_table,
        },
};

module_platform_driver_probe(aspeed_gpio_driver, aspeed_gpio_probe);

MODULE_DESCRIPTION("Aspeed GPIO Driver");
MODULE_LICENSE("GPL");