[PATCH] GTOD: add scx200 HRT clocksource

	tristate "NatSemi SCx200 support"

	depends on !X86_VOYAGER

	help

	  This provides basic support for the National Semiconductor SCx200

	  processor.  Right now this is just a driver for the GPIO pins.

	  This provides basic support for National Semiconductor's

	  (now AMD's) Geode processors.  The driver probes for the

	  PCI-IDs of several on-chip devices, so its a good dependency

	  for other scx200_* drivers.

	  If you don't know what to do here, say N.

	  If compiled as a module, the driver is named scx200.

	  This support is also available as a module.  If compiled as a

	  module, it will be called scx200.

config SCx200HR_TIMER

	tristate "NatSemi SCx200 27MHz High-Resolution Timer Support"

	depends on SCx200 && GENERIC_TIME

	default y

	help

	  This driver provides a clocksource built upon the on-chip

	  27MHz high-resolution timer.  Its also a workaround for

	  NSC Geode SC-1100's buggy TSC, which loses time when the

	  processor goes idle (as is done by the scheduler).  The

	  other workaround is idle=poll boot option.

source "drivers/pcmcia/Kconfig"

obj-$(CONFIG_X86_CYCLONE_TIMER)	+= cyclone.o

obj-$(CONFIG_X86_PM_TIMER)	+= acpi_pm.o

obj-$(CONFIG_SCx200HR_TIMER)	+= scx200_hrt.o

/*

 * Copyright (C) 2006 Jim Cromie

 *

 * This is a clocksource driver for the Geode SCx200's 1 or 27 MHz

 * high-resolution timer.  The Geode SC-1100 (at least) has a buggy

 * time stamp counter (TSC), which loses time unless 'idle=poll' is

 * given as a boot-arg. In its absence, the Generic Timekeeping code

 * will detect and de-rate the bad TSC, allowing this timer to take

 * over timekeeping duties.

 *

 * Based on work by John Stultz, and Ted Phelps (in a 2.6.12-rc6 patch)

 *

 * This program is free software; you can redistribute it and/or

 * modify it under the terms of the GNU General Public License as

 * published by the Free Software Foundation; either version 2 of the

 * License, or (at your option) any later version.

 */

#include <linux/clocksource.h>

#include <linux/init.h>

#include <linux/module.h>

#include <linux/ioport.h>

#include <linux/scx200.h>

#define NAME "scx200_hrt"

static int mhz27;

module_param(mhz27, int, 0);	/* load time only */

MODULE_PARM_DESC(mhz27, "count at 27.0 MHz (default is 1.0 MHz)");

static int ppm;

module_param(ppm, int, 0);	/* load time only */

MODULE_PARM_DESC(ppm, "+-adjust to actual XO freq (ppm)");

/* HiRes Timer configuration register address */

#define SCx200_TMCNFG_OFFSET (SCx200_TIMER_OFFSET + 5)

/* and config settings */

#define HR_TMEN (1 << 0)	/* timer interrupt enable */

#define HR_TMCLKSEL (1 << 1)	/* 1|0 counts at 27|1 MHz */

#define HR_TM27MPD (1 << 2)	/* 1 turns off input clock (power-down) */

/* The base timer frequency, * 27 if selected */

#define HRT_FREQ   1000000

static cycle_t read_hrt(void)

{

	/* Read the timer value */

	return (cycle_t) inl(scx200_cb_base + SCx200_TIMER_OFFSET);

}

#define HRT_SHIFT_1	22

#define HRT_SHIFT_27	26

static struct clocksource cs_hrt = {

	.name		= "scx200_hrt",

	.rating		= 250,

	.read		= read_hrt,

	.mask		= CLOCKSOURCE_MASK(32),

	.is_continuous	= 1,

	/* mult, shift are set based on mhz27 flag */

};

static int __init init_hrt_clocksource(void)

{

	/* Make sure scx200 has initializedd the configuration block */

	if (!scx200_cb_present())

		return -ENODEV;

	/* Reserve the timer's ISA io-region for ourselves */

	if (!request_region(scx200_cb_base + SCx200_TIMER_OFFSET,

			    SCx200_TIMER_SIZE,

			    "NatSemi SCx200 High-Resolution Timer")) {

		printk(KERN_WARNING NAME ": unable to lock timer region\n");

		return -ENODEV;

	}

	/* write timer config */

	outb(HR_TMEN | (mhz27) ? HR_TMCLKSEL : 0,

	     scx200_cb_base + SCx200_TMCNFG_OFFSET);

	if (mhz27) {

		cs_hrt.shift = HRT_SHIFT_27;

		cs_hrt.mult = clocksource_hz2mult((HRT_FREQ + ppm) * 27,

						  cs_hrt.shift);

	} else {

		cs_hrt.shift = HRT_SHIFT_1;

		cs_hrt.mult = clocksource_hz2mult(HRT_FREQ + ppm,

						  cs_hrt.shift);

	}

	printk(KERN_INFO "enabling scx200 high-res timer (%s MHz +%d ppm)\n",

		mhz27 ? "27":"1", ppm);

	return clocksource_register(&cs_hrt);

}

module_init(init_hrt_clocksource);

MODULE_AUTHOR("Jim Cromie <jim.cromie@gmail.com>");

MODULE_DESCRIPTION("clocksource on SCx200 HiRes Timer");

MODULE_LICENSE("GPL");