arch/sh/boards/mach-x3proto/ilsel.c

Source file repositories/reference/linux-study-clean/arch/sh/boards/mach-x3proto/ilsel.c

File Facts

System
Linux kernel
Corpus path
arch/sh/boards/mach-x3proto/ilsel.c
Extension
.c
Size
4062 bytes
Lines
157
Domain
Architecture Layer
Bucket
arch/sh
Inferred role
Architecture Layer: exported/initcall integration point
Status
integration implementation candidate

Why This File Exists

CPU and platform-specific kernel glue: boot entry, traps, syscall entry, interrupts, page tables, context switch, and low-level barriers.

Dependency Surface

Detected Declarations

Annotated Snippet

// 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().

Annotation

Implementation Notes