[GitHub/mt8127/android_kernel_alcatel_ttab.git] / drivers / clocksource / scx200_hrt.c

/*
 * 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(struct clocksource *cs)
{
	/* Read the timer value */
	return (cycle_t) inl(scx200_cb_base + SCx200_TIMER_OFFSET);
}

static struct clocksource cs_hrt = {
	.name		= "scx200_hrt",
	.rating		= 250,
	.read		= read_hrt,
	.mask		= CLOCKSOURCE_MASK(32),
	.flags		= CLOCK_SOURCE_IS_CONTINUOUS,
	/* mult, shift are set based on mhz27 flag */
};

static int __init init_hrt_clocksource(void)
{
	u32 freq;
	/* Make sure scx200 has initialized 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")) {
		pr_warn("unable to lock timer region\n");
		return -ENODEV;
	}

	/* write timer config */
	outb(HR_TMEN | (mhz27 ? HR_TMCLKSEL : 0),
	     scx200_cb_base + SCx200_TMCNFG_OFFSET);

	freq = (HRT_FREQ + ppm);
	if (mhz27)
		freq *= 27;

	pr_info("enabling scx200 high-res timer (%s MHz +%d ppm)\n", mhz27 ? "27":"1", ppm);

	return clocksource_register_hz(&cs_hrt, freq);
}

module_init(init_hrt_clocksource);

MODULE_AUTHOR("Jim Cromie <jim.cromie@gmail.com>");
MODULE_DESCRIPTION("clocksource on SCx200 HiRes Timer");
MODULE_LICENSE("GPL");
Commit	Line	Data
6ae7440e JC	1	/*
	2	* Copyright (C) 2006 Jim Cromie
	3	*
	4	* This is a clocksource driver for the Geode SCx200's 1 or 27 MHz
	5	* high-resolution timer. The Geode SC-1100 (at least) has a buggy
	6	* time stamp counter (TSC), which loses time unless 'idle=poll' is
	7	* given as a boot-arg. In its absence, the Generic Timekeeping code
	8	* will detect and de-rate the bad TSC, allowing this timer to take
	9	* over timekeeping duties.
	10	*
	11	* Based on work by John Stultz, and Ted Phelps (in a 2.6.12-rc6 patch)
	12	*
	13	* This program is free software; you can redistribute it and/or
	14	* modify it under the terms of the GNU General Public License as
	15	* published by the Free Software Foundation; either version 2 of the
	16	* License, or (at your option) any later version.
	17	*/
	18
	19	#include <linux/clocksource.h>
	20	#include <linux/init.h>
	21	#include <linux/module.h>
	22	#include <linux/ioport.h>
	23	#include <linux/scx200.h>
	24
	25	#define NAME "scx200_hrt"
	26
	27	static int mhz27;
	28	module_param(mhz27, int, 0); /* load time only */
	29	MODULE_PARM_DESC(mhz27, "count at 27.0 MHz (default is 1.0 MHz)");
	30
	31	static int ppm;
	32	module_param(ppm, int, 0); /* load time only */
	33	MODULE_PARM_DESC(ppm, "+-adjust to actual XO freq (ppm)");
	34
	35	/* HiRes Timer configuration register address */
	36	#define SCx200_TMCNFG_OFFSET (SCx200_TIMER_OFFSET + 5)
	37
	38	/* and config settings */
	39	#define HR_TMEN (1 << 0) /* timer interrupt enable */
	40	#define HR_TMCLKSEL (1 << 1) /* 1\|0 counts at 27\|1 MHz */
	41	#define HR_TM27MPD (1 << 2) /* 1 turns off input clock (power-down) */
	42
	43	/* The base timer frequency, * 27 if selected */
	44	#define HRT_FREQ 1000000
	45
8e19608e	46	static cycle_t read_hrt(struct clocksource *cs)
6ae7440e JC	47	{
	48	/* Read the timer value */
	49	return (cycle_t) inl(scx200_cb_base + SCx200_TIMER_OFFSET);
	50	}
	51
6ae7440e JC	52	static struct clocksource cs_hrt = {
	53	.name = "scx200_hrt",
	54	.rating = 250,
	55	.read = read_hrt,
	56	.mask = CLOCKSOURCE_MASK(32),
73b08d2a	57	.flags = CLOCK_SOURCE_IS_CONTINUOUS,
6ae7440e JC	58	/* mult, shift are set based on mhz27 flag */
	59	};
	60
	61	static int __init init_hrt_clocksource(void)
	62	{
12d6d412	63	u32 freq;
856fe98f	64	/* Make sure scx200 has initialized the configuration block */
6ae7440e JC	65	if (!scx200_cb_present())
	66	return -ENODEV;
	67
	68	/* Reserve the timer's ISA io-region for ourselves */
	69	if (!request_region(scx200_cb_base + SCx200_TIMER_OFFSET,
	70	SCx200_TIMER_SIZE,
	71	"NatSemi SCx200 High-Resolution Timer")) {
d976f762	72	pr_warn("unable to lock timer region\n");
6ae7440e JC	73	return -ENODEV;
	74	}
	75
	76	/* write timer config */
856fe98f	77	outb(HR_TMEN \| (mhz27 ? HR_TMCLKSEL : 0),
6ae7440e JC	78	scx200_cb_base + SCx200_TMCNFG_OFFSET);
6ae7440e JC	79
12d6d412 JS	80	freq = (HRT_FREQ + ppm);
	81	if (mhz27)
	82	freq *= 27;
	83
10ea9d6f	84	pr_info("enabling scx200 high-res timer (%s MHz +%d ppm)\n", mhz27 ? "27":"1", ppm);
6ae7440e	85
12d6d412	86	return clocksource_register_hz(&cs_hrt, freq);
6ae7440e JC	87	}
	88
	89	module_init(init_hrt_clocksource);
	90
	91	MODULE_AUTHOR("Jim Cromie <jim.cromie@gmail.com>");
	92	MODULE_DESCRIPTION("clocksource on SCx200 HiRes Timer");
	93	MODULE_LICENSE("GPL");