// SPDX-License-Identifier: GPL-2.0
/*
 * arch/sh/boards/mach-x3proto/ilsel.c
 *
 * Helper routines for SH-X3 proto board ILSEL.
 *
 * Copyright (C) 2007 - 2010  Paul Mundt
 */
#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt

#include <linux/init.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/bitmap.h>
#include <linux/io.h>
#include <mach/ilsel.h>

/*
 * ILSEL is split across:
 *
 *      ILSEL0 - 0xb8100004 [ Levels  1 -  4 ]
 *      ILSEL1 - 0xb8100006 [ Levels  5 -  8 ]
 *      ILSEL2 - 0xb8100008 [ Levels  9 - 12 ]
 *      ILSEL3 - 0xb810000a [ Levels 13 - 15 ]
 *
 * With each level being relative to an ilsel_source_t.
 */
#define ILSEL_BASE      0xb8100004
#define ILSEL_LEVELS    15

/*
 * ILSEL level map, in descending order from the highest level down.
 *
 * Supported levels are 1 - 15 spread across ILSEL0 - ILSEL4, mapping
 * directly to IRLs. As the IRQs are numbered in reverse order relative
 * to the interrupt level, the level map is carefully managed to ensure a
 * 1:1 mapping between the bit position and the IRQ number.
 *
 * This careful constructions allows ilsel_enable*() to be referenced
 * directly for hooking up an ILSEL set and getting back an IRQ which can
 * subsequently be used for internal accounting in the (optional) disable
 * path.
 */
static unsigned long ilsel_level_map;

static inline unsigned int ilsel_offset(unsigned int bit)
{
        return ILSEL_LEVELS - bit - 1;
}

static inline unsigned long mk_ilsel_addr(unsigned int bit)
{
        return ILSEL_BASE + ((ilsel_offset(bit) >> 1) & ~0x1);
}

static inline unsigned int mk_ilsel_shift(unsigned int bit)
{
        return (ilsel_offset(bit) & 0x3) << 2;
}

static void __ilsel_enable(ilsel_source_t set, unsigned int bit)
{
        unsigned int tmp, shift;
        unsigned long addr;

        pr_notice("enabling ILSEL set %d\n", set);

        addr = mk_ilsel_addr(bit);
        shift = mk_ilsel_shift(bit);

        pr_debug("%s: bit#%d: addr - 0x%08lx (shift %d, set %d)\n",
                 __func__, bit, addr, shift, set);

        tmp = __raw_readw(addr);
        tmp &= ~(0xf << shift);
        tmp |= set << shift;
        __raw_writew(tmp, addr);
}

/**
 * ilsel_enable - Enable an ILSEL set.
 * @set: ILSEL source (see ilsel_source_t enum in include/asm-sh/ilsel.h).
 *
 * Enables a given non-aliased ILSEL source (<= ILSEL_KEY) at the highest
 * available interrupt level. Callers should take care to order callsites
 * noting descending interrupt levels. Aliasing FPGA and external board
 * IRQs need to use ilsel_enable_fixed().
 *
 * The return value is an IRQ number that can later be taken down with
 * ilsel_disable().
 */
int ilsel_enable(ilsel_source_t set)
{
        unsigned int bit;

        if (unlikely(set > ILSEL_KEY)) {
                pr_err("Aliased sources must use ilsel_enable_fixed()\n");
                return -EINVAL;
        }

        do {
                bit = find_first_zero_bit(&ilsel_level_map, ILSEL_LEVELS);
        } while (test_and_set_bit(bit, &ilsel_level_map));

        __ilsel_enable(set, bit);

        return bit;
}
EXPORT_SYMBOL_GPL(ilsel_enable);

/**
 * ilsel_enable_fixed - Enable an ILSEL set at a fixed interrupt level
 * @set: ILSEL source (see ilsel_source_t enum in include/asm-sh/ilsel.h).
 * @level: Interrupt level (1 - 15)
 *
 * Enables a given ILSEL source at a fixed interrupt level. Necessary
 * both for level reservation as well as for aliased sources that only
 * exist on special ILSEL#s.
 *
 * Returns an IRQ number (as ilsel_enable()).
 */
int ilsel_enable_fixed(ilsel_source_t set, unsigned int level)
{
        unsigned int bit = ilsel_offset(level - 1);

        if (test_and_set_bit(bit, &ilsel_level_map))
                return -EBUSY;

        __ilsel_enable(set, bit);

        return bit;
}
EXPORT_SYMBOL_GPL(ilsel_enable_fixed);

/**
 * ilsel_disable - Disable an ILSEL set
 * @irq: Bit position for ILSEL set value (retval from enable routines)
 *
 * Disable a previously enabled ILSEL set.
 */
void ilsel_disable(unsigned int irq)
{
        unsigned long addr;
        unsigned int tmp;

        pr_notice("disabling ILSEL set %d\n", irq);

        addr = mk_ilsel_addr(irq);

        tmp = __raw_readw(addr);
        tmp &= ~(0xf << mk_ilsel_shift(irq));
        __raw_writew(tmp, addr);

        clear_bit(irq, &ilsel_level_map);
}
EXPORT_SYMBOL_GPL(ilsel_disable);