linux/arch/arm/mach-ebsa110/core.c

// SPDX-License-Identifier: GPL-2.0-only
/*
 *  linux/arch/arm/mach-ebsa110/core.c
 *
 *  Copyright (C) 1998-2001 Russell King
 *
 *  Extra MM routines for the EBSA-110 architecture
 */
#include <linux/kernel.h>
#include <linux/mm.h>
#include <linux/interrupt.h>
#include <linux/serial_8250.h>
#include <linux/init.h>
#include <linux/io.h>

#include <mach/hardware.h>
#include <asm/irq.h>
#include <asm/setup.h>
#include <asm/mach-types.h>
#include <asm/page.h>
#include <asm/system_misc.h>

#include <asm/mach/arch.h>
#include <asm/mach/irq.h>
#include <asm/mach/map.h>

#include <asm/mach/time.h>

#include "core.h"

static void ebsa110_mask_irq(struct irq_data *d)
{
	__raw_writeb(1 << d->irq, IRQ_MCLR);
}

static void ebsa110_unmask_irq(struct irq_data *d)
{
	__raw_writeb(1 << d->irq, IRQ_MSET);
}

static struct irq_chip ebsa110_irq_chip = {
	.irq_ack	= ebsa110_mask_irq,
	.irq_mask	= ebsa110_mask_irq,
	.irq_unmask	= ebsa110_unmask_irq,
};
 
static void __init ebsa110_init_irq(void)
{
	unsigned long flags;
	unsigned int irq;

	local_irq_save(flags);
	__raw_writeb(0xff, IRQ_MCLR);
	__raw_writeb(0x55, IRQ_MSET);
	__raw_writeb(0x00, IRQ_MSET);
	if (__raw_readb(IRQ_MASK) != 0x55)
		while (1);
	__raw_writeb(0xff, IRQ_MCLR);	/* clear all interrupt enables */
	local_irq_restore(flags);

	for (irq = 0; irq < NR_IRQS; irq++) {
		irq_set_chip_and_handler(irq, &ebsa110_irq_chip,
					 handle_level_irq);
		irq_clear_status_flags(irq, IRQ_NOREQUEST | IRQ_NOPROBE);
	}
}

static struct map_desc ebsa110_io_desc[] __initdata = {
	/*
	 * sparse external-decode ISAIO space
	 */
	{	/* IRQ_STAT/IRQ_MCLR */
		.virtual	= (unsigned long)IRQ_STAT,
		.pfn		= __phys_to_pfn(TRICK4_PHYS),
		.length		= TRICK4_SIZE,
		.type		= MT_DEVICE
	}, {	/* IRQ_MASK/IRQ_MSET */
		.virtual	= (unsigned long)IRQ_MASK,
		.pfn		= __phys_to_pfn(TRICK3_PHYS),
		.length		= TRICK3_SIZE,
		.type		= MT_DEVICE
	}, {	/* SOFT_BASE */
		.virtual	= (unsigned long)SOFT_BASE,
		.pfn		= __phys_to_pfn(TRICK1_PHYS),
		.length		= TRICK1_SIZE,
		.type		= MT_DEVICE
	}, {	/* PIT_BASE */
		.virtual	= (unsigned long)PIT_BASE,
		.pfn		= __phys_to_pfn(TRICK0_PHYS),
		.length		= TRICK0_SIZE,
		.type		= MT_DEVICE
	},

	/*
	 * self-decode ISAIO space
	 */
	{
		.virtual	= ISAIO_BASE,
		.pfn		= __phys_to_pfn(ISAIO_PHYS),
		.length		= ISAIO_SIZE,
		.type		= MT_DEVICE
	}, {
		.virtual	= ISAMEM_BASE,
		.pfn		= __phys_to_pfn(ISAMEM_PHYS),
		.length		= ISAMEM_SIZE,
		.type		= MT_DEVICE
	}
};

static void __init ebsa110_map_io(void)
{
	iotable_init(ebsa110_io_desc, ARRAY_SIZE(ebsa110_io_desc));
}

static void __iomem *ebsa110_ioremap_caller(phys_addr_t cookie, size_t size,
					    unsigned int flags, void *caller)
{
	return (void __iomem *)cookie;
}

static void ebsa110_iounmap(volatile void __iomem *io_addr)
{}

static void __init ebsa110_init_early(void)
{
	arch_ioremap_caller = ebsa110_ioremap_caller;
	arch_iounmap = ebsa110_iounmap;
}

#define PIT_CTRL		(PIT_BASE + 0x0d)
#define PIT_T2			(PIT_BASE + 0x09)
#define PIT_T1			(PIT_BASE + 0x05)
#define PIT_T0			(PIT_BASE + 0x01)

/*
 * This is the rate at which your MCLK signal toggles (in Hz)
 * This was measured on a 10 digit frequency counter sampling
 * over 1 second.
 */
#define MCLK	47894000

/*
 * This is the rate at which the PIT timers get clocked
 */
#define CLKBY7	(MCLK / 7)

/*
 * This is the counter value.  We tick at 200Hz on this platform.
 */
#define COUNT	((CLKBY7 + (HZ / 2)) / HZ)

/*
 * Get the time offset from the system PIT.  Note that if we have missed an
 * interrupt, then the PIT counter will roll over (ie, be negative).
 * This actually works out to be convenient.
 */
static u32 ebsa110_gettimeoffset(void)
{
	unsigned long offset, count;

	__raw_writeb(0x40, PIT_CTRL);
	count = __raw_readb(PIT_T1);
	count |= __raw_readb(PIT_T1) << 8;

	/*
	 * If count > COUNT, make the number negative.
	 */
	if (count > COUNT)
		count |= 0xffff0000;

	offset = COUNT;
	offset -= count;

	/*
	 * `offset' is in units of timer counts.  Convert
	 * offset to units of microseconds.
	 */
	offset = offset * (1000000 / HZ) / COUNT;

	return offset * 1000;
}

static irqreturn_t
ebsa110_timer_interrupt(int irq, void *dev_id)
{
	u32 count;

	/* latch and read timer 1 */
	__raw_writeb(0x40, PIT_CTRL);
	count = __raw_readb(PIT_T1);
	count |= __raw_readb(PIT_T1) << 8;

	count += COUNT;

	__raw_writeb(count & 0xff, PIT_T1);
	__raw_writeb(count >> 8, PIT_T1);

	timer_tick();

	return IRQ_HANDLED;
}

/*
 * Set up timer interrupt.
 */
void __init ebsa110_timer_init(void)
{
	int irq = IRQ_EBSA110_TIMER0;

	arch_gettimeoffset = ebsa110_gettimeoffset;

	/*
	 * Timer 1, mode 2, LSB/MSB
	 */
	__raw_writeb(0x70, PIT_CTRL);
	__raw_writeb(COUNT & 0xff, PIT_T1);
	__raw_writeb(COUNT >> 8, PIT_T1);

	if (request_irq(irq, ebsa110_timer_interrupt, IRQF_TIMER | IRQF_IRQPOLL,
			"EBSA110 Timer Tick", NULL))
		pr_err("Failed to request irq %d (EBSA110 Timer Tick)\n", irq);
}

static struct plat_serial8250_port serial_platform_data[] = {
	{
		.iobase		= 0x3f8,
		.irq		= 1,
		.uartclk	= 1843200,
		.regshift	= 0,
		.iotype		= UPIO_PORT,
		.flags		= UPF_BOOT_AUTOCONF | UPF_SKIP_TEST,
	},
	{
		.iobase		= 0x2f8,
		.irq		= 2,
		.uartclk	= 1843200,
		.regshift	= 0,
		.iotype		= UPIO_PORT,
		.flags		= UPF_BOOT_AUTOCONF | UPF_SKIP_TEST,
	},
	{ },
};

static struct platform_device serial_device = {
	.name			= "serial8250",
	.id			= PLAT8250_DEV_PLATFORM,
	.dev			= {
		.platform_data	= serial_platform_data,
	},
};

static struct resource am79c961_resources[] = {
	{
		.start		= 0x220,
		.end		= 0x238,
		.flags		= IORESOURCE_IO,
	}, {
		.start		= IRQ_EBSA110_ETHERNET,
		.end		= IRQ_EBSA110_ETHERNET,
		.flags		= IORESOURCE_IRQ,
	},
};

static struct platform_device am79c961_device = {
	.name			= "am79c961",
	.id			= -1,
	.num_resources		= ARRAY_SIZE(am79c961_resources),
	.resource		= am79c961_resources,
};

static struct platform_device *ebsa110_devices[] = {
	&serial_device,
	&am79c961_device,
};

/*
 * EBSA110 idling methodology:
 *
 * We can not execute the "wait for interrupt" instruction since that
 * will stop our MCLK signal (which provides the clock for the glue
 * logic, and therefore the timer interrupt).
 *
 * Instead, we spin, polling the IRQ_STAT register for the occurrence
 * of any interrupt with core clock down to the memory clock.
 */
static void ebsa110_idle(void)
{
	const char *irq_stat = (char *)0xff000000;

	/* disable clock switching */
	asm volatile ("mcr p15, 0, ip, c15, c2, 2" : : : "cc");

	/* wait for an interrupt to occur */
	while (!*irq_stat);

	/* enable clock switching */
	asm volatile ("mcr p15, 0, ip, c15, c1, 2" : : : "cc");
}

static int __init ebsa110_init(void)
{
	arm_pm_idle = ebsa110_idle;
	return platform_add_devices(ebsa110_devices, ARRAY_SIZE(ebsa110_devices));
}

arch_initcall(ebsa110_init);

static void ebsa110_restart(enum reboot_mode mode, const char *cmd)
{
	soft_restart(0x80000000);
}

MACHINE_START(EBSA110, "EBSA110")
	/* Maintainer: Russell King */
	.atag_offset	= 0x400,
	.reserve_lp0	= 1,
	.reserve_lp2	= 1,
	.map_io		= ebsa110_map_io,
	.init_early	= ebsa110_init_early,
	.init_irq	= ebsa110_init_irq,
	.init_time	= ebsa110_timer_init,
	.restart	= ebsa110_restart,
MACHINE_END