Adding upstream version 5.10.209.upstream/5.10.209upstream

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

4 files changed, 780 insertions, 0 deletions

diff --git a/arch/m68k/q40/Makefile b/arch/m68k/q40/Makefile
new file mode 100644
index 000000000..4e4dc9104
--- /dev/null
+++ b/arch/m68k/q40/Makefile
@@ -0,0 +1,6 @@
+# SPDX-License-Identifier: GPL-2.0-only
+#
+# Makefile for Linux arch/m68k/q40 source directory
+#
+
+obj-y		:= config.o q40ints.o
diff --git a/arch/m68k/q40/README b/arch/m68k/q40/README
new file mode 100644
index 000000000..a4991d2d8
--- /dev/null
+++ b/arch/m68k/q40/README
@@ -0,0 +1,138 @@
+Linux for the Q40
+=================
+
+You may try http://www.geocities.com/SiliconValley/Bay/2602/ for
+some up to date information. Booter and other tools will be also
+available from this place or http://ftp.uni-erlangen.de/pub/unix/Linux/680x0/q40/
+and mirrors.
+
+Hints to documentation usually refer to the linux source tree in
+/usr/src/linux/Documentation unless URL given.
+
+It seems IRQ unmasking can't be safely done on a Q40. IRQ probing
+is not implemented - do not try it! (See below)
+
+For a list of kernel command-line options read the documentation for the
+particular device drivers.
+
+The floppy imposes a very high interrupt load on the CPU, approx 30K/s.
+When something blocks interrupts (HD) it will lose some of them, so far
+this is not known to have caused any data loss. On highly loaded systems
+it can make the floppy very slow or practically stop. Other Q40 OS' simply
+poll the floppy for this reason - something that can't be done in Linux.
+Only possible cure is getting a 82072 controller with fifo instead of
+the 8272A.
+
+drivers used by the Q40, apart from the very obvious (console etc.):
+	drivers/char/q40_keyb.c		# use PC keymaps for national keyboards
+		     serial.c		# normal PC driver - any speed
+	             lp.c		# printer driver
+		     genrtc.c		# RTC
+		char/joystick/*		# most of this should work, not
+				        # in default config.in
+	        block/q40ide.c		# startup for ide
+		      ide*		# see Documentation/ide/ide.rst
+		      floppy.c		# normal PC driver, DMA emu in asm/floppy.h
+					# and arch/m68k/kernel/entry.S
+					# see drivers/block/README.fd
+		net/ne.c
+		video/q40fb.c
+		parport/*
+		sound/dmasound_core.c
+		      dmasound_q40.c
+
+Various other PC drivers can be enabled simply by adding them to
+arch/m68k/config.in, especially 8 bit devices should be without any
+problems. For cards using 16bit io/mem more care is required, like
+checking byte order issues, hacking memcpy_*_io etc.
+
+
+Debugging
+=========
+
+Upon startup the kernel will usually output "ABCQGHIJ" into the SRAM,
+preceded by the booter signature. This is a trace just in case something
+went wrong during earliest setup stages of head.S.
+**Changed** to preserve SRAM contents by default, this is only done when
+requested - SRAM must start with '%LX$' signature to do this. '-d' option
+to 'lxx' loader enables this.
+
+SRAM can also be used as additional console device, use debug=mem.
+This will save kernel startup msgs into SRAM, the screen will display
+only the penguin - and shell prompt if it gets that far..
+Unfortunately only 2000 bytes are available.
+
+Serial console works and can also be used for debugging, see loader_txt
+
+Most problems seem to be caused by fawlty or badly configured io-cards or
+hard drives anyway.
+Make sure to configure the parallel port as SPP and remove IRQ/DMA jumpers
+for first testing. The Q40 does not support DMA and may have trouble with
+parallel ports version of interrupts.
+
+
+Q40 Hardware Description
+========================
+
+This is just an overview, see asm-m68k/* for details ask if you have any
+questions.
+
+The Q40 consists of a 68040@40 MHz, 1MB video RAM, up to 32MB RAM, AT-style
+keyboard interface, 1 Programmable LED, 2x8bit DACs and up to 1MB ROM, 1MB
+shadow ROM.
+The Q60 has any of 68060 or 68LC060 and up to 128 MB RAM.
+
+Most interfacing like floppy, IDE, serial and parallel ports is done via ISA
+slots. The ISA io and mem range is mapped (sparse&byteswapped!) into separate
+regions of the memory.
+The main interrupt register IIRQ_REG will indicate whether an IRQ was internal
+or from some ISA devices, EIRQ_REG can distinguish up to 8 ISA IRQs.
+
+The Q40 custom chip is programmable to provide 2 periodic timers:
+	- 50 or 200 Hz - level 2, !!THIS CAN'T BE DISABLED!!
+	- 10 or 20 KHz - level 4, used for dma-sound
+
+Linux uses the 200 Hz interrupt for timer and beep by default.
+
+
+Interrupts
+==========
+
+q40 master chip handles only a subset of level triggered interrupts.
+
+Linux has some requirements wrt interrupt architecture, these are
+to my knowledge:
+	(a) interrupt handler must not be reentered even when sti() is called
+	    from within handler
+	(b) working enable/disable_irq
+
+Luckily these requirements are only important for drivers shared
+with other architectures - ide,serial,parallel, ethernet.
+q40ints.c now contains a trivial hack for (a), (b) is more difficult
+because only irq's 4-15 can be disabled - and only all of them at once.
+Thus disable_irq() can effectively block the machine if the driver goes
+asleep.
+One thing to keep in mind when hacking around the interrupt code is
+that there is no way to find out which IRQ caused a request, [EI]IRQ_REG
+displays current state of the various IRQ lines.
+
+Keyboard
+========
+
+q40 receives AT make/break codes from the keyboard, these are translated to
+the PC scancodes x86 Linux uses. So by theory every national keyboard should
+work just by loading the appropriate x86 keytable - see any national-HOWTO.
+
+Unfortunately the AT->PC translation isn't quite trivial and even worse, my
+documentation of it is absolutely minimal - thus some exotic keys may not
+behave exactly as expected.
+
+There is still hope that it can be fixed completely though. If you encounter
+problems, email me ideally this:
+	- exact keypress/release sequence
+	- 'showkey -s' run on q40, non-X session
+	- 'showkey -s' run on a PC, non-X session
+	- AT codes as displayed by the q40 debugging ROM
+btw if the showkey output from PC and Q40 doesn't differ then you have some
+classic configuration problem - don't send me anything in this case
+
diff --git a/arch/m68k/q40/config.c b/arch/m68k/q40/config.c
new file mode 100644
index 000000000..4627de3c0
--- /dev/null
+++ b/arch/m68k/q40/config.c
@@ -0,0 +1,304 @@
+/*
+ *  arch/m68k/q40/config.c
+ *
+ *  Copyright (C) 1999 Richard Zidlicky
+ *
+ * originally based on:
+ *
+ *  linux/bvme/config.c
+ *
+ * This file is subject to the terms and conditions of the GNU General Public
+ * License.  See the file README.legal in the main directory of this archive
+ * for more details.
+ */
+
+#include <linux/errno.h>
+#include <linux/types.h>
+#include <linux/kernel.h>
+#include <linux/mm.h>
+#include <linux/tty.h>
+#include <linux/console.h>
+#include <linux/linkage.h>
+#include <linux/init.h>
+#include <linux/major.h>
+#include <linux/serial_reg.h>
+#include <linux/rtc.h>
+#include <linux/vt_kern.h>
+#include <linux/bcd.h>
+#include <linux/platform_device.h>
+
+#include <asm/io.h>
+#include <asm/bootinfo.h>
+#include <asm/setup.h>
+#include <asm/irq.h>
+#include <asm/traps.h>
+#include <asm/machdep.h>
+#include <asm/q40_master.h>
+
+extern void q40_init_IRQ(void);
+static void q40_get_model(char *model);
+extern void q40_sched_init(irq_handler_t handler);
+
+static int q40_hwclk(int, struct rtc_time *);
+static unsigned int q40_get_ss(void);
+static int q40_get_rtc_pll(struct rtc_pll_info *pll);
+static int q40_set_rtc_pll(struct rtc_pll_info *pll);
+
+extern void q40_mksound(unsigned int /*freq*/, unsigned int /*ticks*/);
+
+static void q40_mem_console_write(struct console *co, const char *b,
+				  unsigned int count);
+
+extern int ql_ticks;
+
+static struct console q40_console_driver = {
+	.name	= "debug",
+	.write	= q40_mem_console_write,
+	.flags	= CON_PRINTBUFFER,
+	.index	= -1,
+};
+
+
+/* early debugging function:*/
+extern char *q40_mem_cptr; /*=(char *)0xff020000;*/
+static int _cpleft;
+
+static void q40_mem_console_write(struct console *co, const char *s,
+				  unsigned int count)
+{
+	const char *p = s;
+
+	if (count < _cpleft) {
+		while (count-- > 0) {
+			*q40_mem_cptr = *p++;
+			q40_mem_cptr += 4;
+			_cpleft--;
+		}
+	}
+}
+
+static int __init q40_debug_setup(char *arg)
+{
+	/* useful for early debugging stages - writes kernel messages into SRAM */
+	if (MACH_IS_Q40 && !strncmp(arg, "mem", 3)) {
+		/*pr_info("using NVRAM debug, q40_mem_cptr=%p\n",q40_mem_cptr);*/
+		_cpleft = 2000 - ((long)q40_mem_cptr-0xff020000) / 4;
+		register_console(&q40_console_driver);
+	}
+	return 0;
+}
+
+early_param("debug", q40_debug_setup);
+
+#if 0
+void printq40(char *str)
+{
+	int l = strlen(str);
+	char *p = q40_mem_cptr;
+
+	while (l-- > 0 && _cpleft-- > 0) {
+		*p = *str++;
+		p += 4;
+	}
+	q40_mem_cptr = p;
+}
+#endif
+
+static int halted;
+
+#ifdef CONFIG_HEARTBEAT
+static void q40_heartbeat(int on)
+{
+	if (halted)
+		return;
+
+	if (on)
+		Q40_LED_ON();
+	else
+		Q40_LED_OFF();
+}
+#endif
+
+static void q40_reset(void)
+{
+	halted = 1;
+	pr_info("*******************************************\n"
+		"Called q40_reset : press the RESET button!!\n"
+		"*******************************************\n");
+	Q40_LED_ON();
+	while (1)
+		;
+}
+
+static void q40_halt(void)
+{
+	halted = 1;
+	pr_info("*******************\n"
+		"  Called q40_halt\n"
+		"*******************\n");
+	Q40_LED_ON();
+	while (1)
+		;
+}
+
+static void q40_get_model(char *model)
+{
+	sprintf(model, "Q40");
+}
+
+static unsigned int serports[] =
+{
+	0x3f8,0x2f8,0x3e8,0x2e8,0
+};
+
+static void __init q40_disable_irqs(void)
+{
+	unsigned i, j;
+
+	j = 0;
+	while ((i = serports[j++]))
+		outb(0, i + UART_IER);
+	master_outb(0, EXT_ENABLE_REG);
+	master_outb(0, KEY_IRQ_ENABLE_REG);
+}
+
+void __init config_q40(void)
+{
+	mach_sched_init = q40_sched_init;
+
+	mach_init_IRQ = q40_init_IRQ;
+	mach_hwclk = q40_hwclk;
+	mach_get_ss = q40_get_ss;
+	mach_get_rtc_pll = q40_get_rtc_pll;
+	mach_set_rtc_pll = q40_set_rtc_pll;
+
+	mach_reset = q40_reset;
+	mach_get_model = q40_get_model;
+
+#if IS_ENABLED(CONFIG_INPUT_M68K_BEEP)
+	mach_beep = q40_mksound;
+#endif
+#ifdef CONFIG_HEARTBEAT
+	mach_heartbeat = q40_heartbeat;
+#endif
+	mach_halt = q40_halt;
+
+	/* disable a few things that SMSQ might have left enabled */
+	q40_disable_irqs();
+
+	/* no DMA at all, but ide-scsi requires it.. make sure
+	 * all physical RAM fits into the boundary - otherwise
+	 * allocator may play costly and useless tricks */
+	mach_max_dma_address = 1024*1024*1024;
+}
+
+
+int __init q40_parse_bootinfo(const struct bi_record *rec)
+{
+	return 1;
+}
+
+/*
+ * Looks like op is non-zero for setting the clock, and zero for
+ * reading the clock.
+ *
+ *  struct hwclk_time {
+ *         unsigned        sec;       0..59
+ *         unsigned        min;       0..59
+ *         unsigned        hour;      0..23
+ *         unsigned        day;       1..31
+ *         unsigned        mon;       0..11
+ *         unsigned        year;      00...
+ *         int             wday;      0..6, 0 is Sunday, -1 means unknown/don't set
+ * };
+ */
+
+static int q40_hwclk(int op, struct rtc_time *t)
+{
+	if (op) {
+		/* Write.... */
+		Q40_RTC_CTRL |= Q40_RTC_WRITE;
+
+		Q40_RTC_SECS = bin2bcd(t->tm_sec);
+		Q40_RTC_MINS = bin2bcd(t->tm_min);
+		Q40_RTC_HOUR = bin2bcd(t->tm_hour);
+		Q40_RTC_DATE = bin2bcd(t->tm_mday);
+		Q40_RTC_MNTH = bin2bcd(t->tm_mon + 1);
+		Q40_RTC_YEAR = bin2bcd(t->tm_year%100);
+		if (t->tm_wday >= 0)
+			Q40_RTC_DOW = bin2bcd(t->tm_wday+1);
+
+		Q40_RTC_CTRL &= ~(Q40_RTC_WRITE);
+	} else {
+		/* Read....  */
+		Q40_RTC_CTRL |= Q40_RTC_READ;
+
+		t->tm_year = bcd2bin (Q40_RTC_YEAR);
+		t->tm_mon  = bcd2bin (Q40_RTC_MNTH)-1;
+		t->tm_mday = bcd2bin (Q40_RTC_DATE);
+		t->tm_hour = bcd2bin (Q40_RTC_HOUR);
+		t->tm_min  = bcd2bin (Q40_RTC_MINS);
+		t->tm_sec  = bcd2bin (Q40_RTC_SECS);
+
+		Q40_RTC_CTRL &= ~(Q40_RTC_READ);
+
+		if (t->tm_year < 70)
+			t->tm_year += 100;
+		t->tm_wday = bcd2bin(Q40_RTC_DOW)-1;
+	}
+
+	return 0;
+}
+
+static unsigned int q40_get_ss(void)
+{
+	return bcd2bin(Q40_RTC_SECS);
+}
+
+/* get and set PLL calibration of RTC clock */
+#define Q40_RTC_PLL_MASK ((1<<5)-1)
+#define Q40_RTC_PLL_SIGN (1<<5)
+
+static int q40_get_rtc_pll(struct rtc_pll_info *pll)
+{
+	int tmp = Q40_RTC_CTRL;
+
+	pll->pll_ctrl = 0;
+	pll->pll_value = tmp & Q40_RTC_PLL_MASK;
+	if (tmp & Q40_RTC_PLL_SIGN)
+		pll->pll_value = -pll->pll_value;
+	pll->pll_max = 31;
+	pll->pll_min = -31;
+	pll->pll_posmult = 512;
+	pll->pll_negmult = 256;
+	pll->pll_clock = 125829120;
+
+	return 0;
+}
+
+static int q40_set_rtc_pll(struct rtc_pll_info *pll)
+{
+	if (!pll->pll_ctrl) {
+		/* the docs are a bit unclear so I am doublesetting */
+		/* RTC_WRITE here ... */
+		int tmp = (pll->pll_value & 31) | (pll->pll_value<0 ? 32 : 0) |
+			  Q40_RTC_WRITE;
+		Q40_RTC_CTRL |= Q40_RTC_WRITE;
+		Q40_RTC_CTRL = tmp;
+		Q40_RTC_CTRL &= ~(Q40_RTC_WRITE);
+		return 0;
+	} else
+		return -EINVAL;
+}
+
+static __init int q40_add_kbd_device(void)
+{
+	struct platform_device *pdev;
+
+	if (!MACH_IS_Q40)
+		return -ENODEV;
+
+	pdev = platform_device_register_simple("q40kbd", -1, NULL, 0);
+	return PTR_ERR_OR_ZERO(pdev);
+}
+arch_initcall(q40_add_kbd_device);
diff --git a/arch/m68k/q40/q40ints.c b/arch/m68k/q40/q40ints.c
new file mode 100644
index 000000000..1c696906c
--- /dev/null
+++ b/arch/m68k/q40/q40ints.c
@@ -0,0 +1,332 @@
+/*
+ * arch/m68k/q40/q40ints.c
+ *
+ * Copyright (C) 1999,2001 Richard Zidlicky
+ *
+ * This file is subject to the terms and conditions of the GNU General Public
+ * License.  See the file COPYING in the main directory of this archive
+ * for more details.
+ *
+ * .. used to be loosely based on bvme6000ints.c
+ *
+ */
+
+#include <linux/types.h>
+#include <linux/kernel.h>
+#include <linux/errno.h>
+#include <linux/interrupt.h>
+#include <linux/irq.h>
+
+#include <asm/ptrace.h>
+#include <asm/traps.h>
+
+#include <asm/q40_master.h>
+#include <asm/q40ints.h>
+
+/*
+ * Q40 IRQs are defined as follows:
+ *            3,4,5,6,7,10,11,14,15 : ISA dev IRQs
+ *            16-31: reserved
+ *            32   : keyboard int
+ *            33   : frame int (50/200 Hz periodic timer)
+ *            34   : sample int (10/20 KHz periodic timer)
+ *
+*/
+
+static void q40_irq_handler(unsigned int, struct pt_regs *fp);
+static void q40_irq_enable(struct irq_data *data);
+static void q40_irq_disable(struct irq_data *data);
+
+unsigned short q40_ablecount[35];
+unsigned short q40_state[35];
+
+static unsigned int q40_irq_startup(struct irq_data *data)
+{
+	unsigned int irq = data->irq;
+
+	/* test for ISA ints not implemented by HW */
+	switch (irq) {
+	case 1: case 2: case 8: case 9:
+	case 11: case 12: case 13:
+		pr_warn("%s: ISA IRQ %d not implemented by HW\n", __func__,
+			irq);
+		/* FIXME return -ENXIO; */
+	}
+	return 0;
+}
+
+static void q40_irq_shutdown(struct irq_data *data)
+{
+}
+
+static struct irq_chip q40_irq_chip = {
+	.name		= "q40",
+	.irq_startup	= q40_irq_startup,
+	.irq_shutdown	= q40_irq_shutdown,
+	.irq_enable	= q40_irq_enable,
+	.irq_disable	= q40_irq_disable,
+};
+
+/*
+ * void q40_init_IRQ (void)
+ *
+ * Parameters:	None
+ *
+ * Returns:	Nothing
+ *
+ * This function is called during kernel startup to initialize
+ * the q40 IRQ handling routines.
+ */
+
+static int disabled;
+
+void __init q40_init_IRQ(void)
+{
+	m68k_setup_irq_controller(&q40_irq_chip, handle_simple_irq, 1,
+				  Q40_IRQ_MAX);
+
+	/* setup handler for ISA ints */
+	m68k_setup_auto_interrupt(q40_irq_handler);
+
+	m68k_irq_startup_irq(IRQ_AUTO_2);
+	m68k_irq_startup_irq(IRQ_AUTO_4);
+
+	/* now enable some ints.. */
+	master_outb(1, EXT_ENABLE_REG);  /* ISA IRQ 5-15 */
+
+	/* make sure keyboard IRQ is disabled */
+	master_outb(0, KEY_IRQ_ENABLE_REG);
+}
+
+
+/*
+ * this stuff doesn't really belong here..
+ */
+
+int ql_ticks;              /* 200Hz ticks since last jiffie */
+static int sound_ticks;
+
+#define SVOL 45
+
+void q40_mksound(unsigned int hz, unsigned int ticks)
+{
+	/* for now ignore hz, except that hz==0 switches off sound */
+	/* simply alternate the ampl (128-SVOL)-(128+SVOL)-..-.. at 200Hz */
+	if (hz == 0) {
+		if (sound_ticks)
+			sound_ticks = 1;
+
+		*DAC_LEFT = 128;
+		*DAC_RIGHT = 128;
+
+		return;
+	}
+	/* sound itself is done in q40_timer_int */
+	if (sound_ticks == 0)
+		sound_ticks = 1000; /* pretty long beep */
+	sound_ticks = ticks << 1;
+}
+
+static irqreturn_t q40_timer_int(int irq, void *dev_id)
+{
+	irq_handler_t timer_routine = dev_id;
+
+	ql_ticks = ql_ticks ? 0 : 1;
+	if (sound_ticks) {
+		unsigned char sval=(sound_ticks & 1) ? 128-SVOL : 128+SVOL;
+		sound_ticks--;
+		*DAC_LEFT=sval;
+		*DAC_RIGHT=sval;
+	}
+
+	if (!ql_ticks) {
+		unsigned long flags;
+
+		local_irq_save(flags);
+		timer_routine(0, NULL);
+		local_irq_restore(flags);
+	}
+	return IRQ_HANDLED;
+}
+
+void q40_sched_init (irq_handler_t timer_routine)
+{
+	int timer_irq;
+
+	timer_irq = Q40_IRQ_FRAME;
+
+	if (request_irq(timer_irq, q40_timer_int, 0, "timer", timer_routine))
+		panic("Couldn't register timer int");
+
+	master_outb(-1, FRAME_CLEAR_REG);
+	master_outb( 1, FRAME_RATE_REG);
+}
+
+
+/*
+ * tables to translate bits into IRQ numbers
+ * it is a good idea to order the entries by priority
+ *
+*/
+
+struct IRQ_TABLE{ unsigned mask; int irq ;};
+#if 0
+static struct IRQ_TABLE iirqs[]={
+  {Q40_IRQ_FRAME_MASK,Q40_IRQ_FRAME},
+  {Q40_IRQ_KEYB_MASK,Q40_IRQ_KEYBOARD},
+  {0,0}};
+#endif
+static struct IRQ_TABLE eirqs[] = {
+  { .mask = Q40_IRQ3_MASK,	.irq = 3 },	/* ser 1 */
+  { .mask = Q40_IRQ4_MASK,	.irq = 4 },	/* ser 2 */
+  { .mask = Q40_IRQ14_MASK,	.irq = 14 },	/* IDE 1 */
+  { .mask = Q40_IRQ15_MASK,	.irq = 15 },	/* IDE 2 */
+  { .mask = Q40_IRQ6_MASK,	.irq = 6 },	/* floppy, handled elsewhere */
+  { .mask = Q40_IRQ7_MASK,	.irq = 7 },	/* par */
+  { .mask = Q40_IRQ5_MASK,	.irq = 5 },
+  { .mask = Q40_IRQ10_MASK,	.irq = 10 },
+  {0,0}
+};
+
+/* complain only this many times about spurious ints : */
+static int ccleirq=60;    /* ISA dev IRQs*/
+/*static int cclirq=60;*/     /* internal */
+
+/* FIXME: add shared ints,mask,unmask,probing.... */
+
+#define IRQ_INPROGRESS 1
+/*static unsigned short saved_mask;*/
+//static int do_tint=0;
+
+#define DEBUG_Q40INT
+/*#define IP_USE_DISABLE *//* would be nice, but crashes ???? */
+
+static int mext_disabled=0;  /* ext irq disabled by master chip? */
+static int aliased_irq=0;  /* how many times inside handler ?*/
+
+
+/* got interrupt, dispatch to ISA or keyboard/timer IRQs */
+static void q40_irq_handler(unsigned int irq, struct pt_regs *fp)
+{
+	unsigned mir, mer;
+	int i;
+
+//repeat:
+	mir = master_inb(IIRQ_REG);
+#ifdef CONFIG_BLK_DEV_FD
+	if ((mir & Q40_IRQ_EXT_MASK) &&
+	    (master_inb(EIRQ_REG) & Q40_IRQ6_MASK)) {
+		floppy_hardint();
+		return;
+	}
+#endif
+	switch (irq) {
+	case 4:
+	case 6:
+		do_IRQ(Q40_IRQ_SAMPLE, fp);
+		return;
+	}
+	if (mir & Q40_IRQ_FRAME_MASK) {
+		do_IRQ(Q40_IRQ_FRAME, fp);
+		master_outb(-1, FRAME_CLEAR_REG);
+	}
+	if ((mir & Q40_IRQ_SER_MASK) || (mir & Q40_IRQ_EXT_MASK)) {
+		mer = master_inb(EIRQ_REG);
+		for (i = 0; eirqs[i].mask; i++) {
+			if (mer & eirqs[i].mask) {
+				irq = eirqs[i].irq;
+/*
+ * There is a little mess wrt which IRQ really caused this irq request. The
+ * main problem is that IIRQ_REG and EIRQ_REG reflect the state when they
+ * are read - which is long after the request came in. In theory IRQs should
+ * not just go away but they occasionally do
+ */
+				if (irq > 4 && irq <= 15 && mext_disabled) {
+					/*aliased_irq++;*/
+					goto iirq;
+				}
+				if (q40_state[irq] & IRQ_INPROGRESS) {
+					/* some handlers do local_irq_enable() for irq latency reasons, */
+					/* however reentering an active irq handler is not permitted */
+#ifdef IP_USE_DISABLE
+					/* in theory this is the better way to do it because it still */
+					/* lets through eg the serial irqs, unfortunately it crashes */
+					disable_irq(irq);
+					disabled = 1;
+#else
+					/*pr_warn("IRQ_INPROGRESS detected for irq %d, disabling - %s disabled\n",
+						irq, disabled ? "already" : "not yet"); */
+					fp->sr = (((fp->sr) & (~0x700))+0x200);
+					disabled = 1;
+#endif
+					goto iirq;
+				}
+				q40_state[irq] |= IRQ_INPROGRESS;
+				do_IRQ(irq, fp);
+				q40_state[irq] &= ~IRQ_INPROGRESS;
+
+				/* naively enable everything, if that fails than    */
+				/* this function will be reentered immediately thus */
+				/* getting another chance to disable the IRQ        */
+
+				if (disabled) {
+#ifdef IP_USE_DISABLE
+					if (irq > 4) {
+						disabled = 0;
+						enable_irq(irq);
+					}
+#else
+					disabled = 0;
+					/*pr_info("reenabling irq %d\n", irq); */
+#endif
+				}
+// used to do 'goto repeat;' here, this delayed bh processing too long
+				return;
+			}
+		}
+		if (mer && ccleirq > 0 && !aliased_irq) {
+			pr_warn("ISA interrupt from unknown source? EIRQ_REG = %x\n",
+				mer);
+			ccleirq--;
+		}
+	}
+ iirq:
+	mir = master_inb(IIRQ_REG);
+	/* should test whether keyboard irq is really enabled, doing it in defhand */
+	if (mir & Q40_IRQ_KEYB_MASK)
+		do_IRQ(Q40_IRQ_KEYBOARD, fp);
+
+	return;
+}
+
+void q40_irq_enable(struct irq_data *data)
+{
+	unsigned int irq = data->irq;
+
+	if (irq >= 5 && irq <= 15) {
+		mext_disabled--;
+		if (mext_disabled > 0)
+			pr_warn("q40_irq_enable : nested disable/enable\n");
+		if (mext_disabled == 0)
+			master_outb(1, EXT_ENABLE_REG);
+	}
+}
+
+
+void q40_irq_disable(struct irq_data *data)
+{
+	unsigned int irq = data->irq;
+
+	/* disable ISA iqs : only do something if the driver has been
+	 * verified to be Q40 "compatible" - right now IDE, NE2K
+	 * Any driver should not attempt to sleep across disable_irq !!
+	 */
+
+	if (irq >= 5 && irq <= 15) {
+		master_outb(0, EXT_ENABLE_REG);
+		mext_disabled++;
+		if (mext_disabled > 1)
+			pr_info("disable_irq nesting count %d\n",
+				mext_disabled);
+	}
+}