// SPDX-License-Identifier: GPL-2.0-only
/*
 * bcsr.h -- Db1xxx/Pb1xxx Devboard CPLD registers ("BCSR") abstraction.
 *
 * All Alchemy development boards (except, of course, the weird PB1000)
 * have a few registers in a CPLD with standardised layout; they mostly
 * only differ in base address.
 * All registers are 16bits wide with 32bit spacing.
 */

#include <linux/interrupt.h>
#include <linux/irqchip/chained_irq.h>
#include <linux/init.h>
#include <linux/export.h>
#include <linux/spinlock.h>
#include <linux/irq.h>
#include <asm/addrspace.h>
#include <asm/io.h>
#include <asm/mach-db1x00/bcsr.h>

static struct bcsr_reg {
        void __iomem *raddr;
        spinlock_t lock;
} bcsr_regs[BCSR_CNT];

static void __iomem *bcsr_virt; /* KSEG1 addr of BCSR base */
static int bcsr_csc_base;       /* linux-irq of first cascaded irq */

void __init bcsr_init(unsigned long bcsr1_phys, unsigned long bcsr2_phys)
{
        int i;

        bcsr1_phys = KSEG1ADDR(CPHYSADDR(bcsr1_phys));
        bcsr2_phys = KSEG1ADDR(CPHYSADDR(bcsr2_phys));

        bcsr_virt = (void __iomem *)bcsr1_phys;

        for (i = 0; i < BCSR_CNT; i++) {
                if (i >= BCSR_HEXLEDS)
                        bcsr_regs[i].raddr = (void __iomem *)bcsr2_phys +
                                        (0x04 * (i - BCSR_HEXLEDS));
                else
                        bcsr_regs[i].raddr = (void __iomem *)bcsr1_phys +
                                        (0x04 * i);

                spin_lock_init(&bcsr_regs[i].lock);
        }
}

unsigned short bcsr_read(enum bcsr_id reg)
{
        unsigned short r;
        unsigned long flags;

        spin_lock_irqsave(&bcsr_regs[reg].lock, flags);
        r = __raw_readw(bcsr_regs[reg].raddr);
        spin_unlock_irqrestore(&bcsr_regs[reg].lock, flags);
        return r;
}
EXPORT_SYMBOL_GPL(bcsr_read);

void bcsr_write(enum bcsr_id reg, unsigned short val)
{
        unsigned long flags;

        spin_lock_irqsave(&bcsr_regs[reg].lock, flags);
        __raw_writew(val, bcsr_regs[reg].raddr);
        wmb();
        spin_unlock_irqrestore(&bcsr_regs[reg].lock, flags);
}
EXPORT_SYMBOL_GPL(bcsr_write);

void bcsr_mod(enum bcsr_id reg, unsigned short clr, unsigned short set)
{
        unsigned short r;
        unsigned long flags;

        spin_lock_irqsave(&bcsr_regs[reg].lock, flags);
        r = __raw_readw(bcsr_regs[reg].raddr);
        r &= ~clr;
        r |= set;
        __raw_writew(r, bcsr_regs[reg].raddr);
        wmb();
        spin_unlock_irqrestore(&bcsr_regs[reg].lock, flags);
}
EXPORT_SYMBOL_GPL(bcsr_mod);

/*
 * DB1200/PB1200 CPLD IRQ muxer
 */
static void bcsr_csc_handler(struct irq_desc *d)
{
        unsigned short bisr = __raw_readw(bcsr_virt + BCSR_REG_INTSTAT);
        struct irq_chip *chip = irq_desc_get_chip(d);

        chained_irq_enter(chip, d);
        generic_handle_irq(bcsr_csc_base + __ffs(bisr));
        chained_irq_exit(chip, d);
}

static void bcsr_irq_mask(struct irq_data *d)
{
        unsigned short v = 1 << (d->irq - bcsr_csc_base);
        __raw_writew(v, bcsr_virt + BCSR_REG_MASKCLR);
        wmb();
}

static void bcsr_irq_maskack(struct irq_data *d)
{
        unsigned short v = 1 << (d->irq - bcsr_csc_base);
        __raw_writew(v, bcsr_virt + BCSR_REG_MASKCLR);
        __raw_writew(v, bcsr_virt + BCSR_REG_INTSTAT);  /* ack */
        wmb();
}

static void bcsr_irq_unmask(struct irq_data *d)
{
        unsigned short v = 1 << (d->irq - bcsr_csc_base);
        __raw_writew(v, bcsr_virt + BCSR_REG_MASKSET);
        wmb();
}

static struct irq_chip bcsr_irq_type = {
        .name           = "CPLD",
        .irq_mask       = bcsr_irq_mask,
        .irq_mask_ack   = bcsr_irq_maskack,
        .irq_unmask     = bcsr_irq_unmask,
};

void __init bcsr_init_irq(int csc_start, int csc_end, int hook_irq)
{
        unsigned int irq;

        /* mask & enable & ack all */
        __raw_writew(0xffff, bcsr_virt + BCSR_REG_MASKCLR);
        __raw_writew(0xffff, bcsr_virt + BCSR_REG_INTSET);
        __raw_writew(0xffff, bcsr_virt + BCSR_REG_INTSTAT);
        wmb();

        bcsr_csc_base = csc_start;

        for (irq = csc_start; irq <= csc_end; irq++)
                irq_set_chip_and_handler_name(irq, &bcsr_irq_type,
                                              handle_level_irq, "level");

        irq_set_chained_handler(hook_irq, bcsr_csc_handler);
}