linux/drivers/misc/cs5535-mfgpt.c

// SPDX-License-Identifier: GPL-2.0-only
/*
 * Driver for the CS5535/CS5536 Multi-Function General Purpose Timers (MFGPT)
 *
 * Copyright (C) 2006, Advanced Micro Devices, Inc.
 * Copyright (C) 2007  Andres Salomon <[email protected]>
 * Copyright (C) 2009  Andres Salomon <[email protected]>
 *
 * The MFGPTs are documented in AMD Geode CS5536 Companion Device Data Book.
 */

#include <linux/kernel.h>
#include <linux/spinlock.h>
#include <linux/interrupt.h>
#include <linux/module.h>
#include <linux/platform_device.h>
#include <linux/cs5535.h>
#include <linux/slab.h>

#define DRV_NAME …

static int mfgpt_reset_timers;
module_param_named(mfgptfix, mfgpt_reset_timers, int, 0644);
MODULE_PARM_DESC(…) …;

struct cs5535_mfgpt_timer { … };

static struct cs5535_mfgpt_chip { … } cs5535_mfgpt_chip;

int cs5535_mfgpt_toggle_event(struct cs5535_mfgpt_timer *timer, int cmp,
		int event, int enable)
{ … }
EXPORT_SYMBOL_GPL(…);

int cs5535_mfgpt_set_irq(struct cs5535_mfgpt_timer *timer, int cmp, int *irq,
		int enable)
{ … }
EXPORT_SYMBOL_GPL(…);

struct cs5535_mfgpt_timer *cs5535_mfgpt_alloc_timer(int timer_nr, int domain)
{ … }
EXPORT_SYMBOL_GPL(…);

/*
 * XXX: This frees the timer memory, but never resets the actual hardware
 * timer.  The old geode_mfgpt code did this; it would be good to figure
 * out a way to actually release the hardware timer.  See comments below.
 */
void cs5535_mfgpt_free_timer(struct cs5535_mfgpt_timer *timer)
{ … }
EXPORT_SYMBOL_GPL(…);

uint16_t cs5535_mfgpt_read(struct cs5535_mfgpt_timer *timer, uint16_t reg)
{ … }
EXPORT_SYMBOL_GPL(…);

void cs5535_mfgpt_write(struct cs5535_mfgpt_timer *timer, uint16_t reg,
		uint16_t value)
{ … }
EXPORT_SYMBOL_GPL(…);

/*
 * This is a sledgehammer that resets all MFGPT timers. This is required by
 * some broken BIOSes which leave the system in an unstable state
 * (TinyBIOS 0.98, for example; fixed in 0.99).  It's uncertain as to
 * whether or not this secret MSR can be used to release individual timers.
 * Jordan tells me that he and Mitch once played w/ it, but it's unclear
 * what the results of that were (and they experienced some instability).
 */
static void reset_all_timers(void)
{ … }

/*
 * This is another sledgehammer to reset all MFGPT timers.
 * Instead of using the undocumented bit method it clears
 * IRQ, NMI and RESET settings.
 */
static void soft_reset(void)
{ … }

/*
 * Check whether any MFGPTs are available for the kernel to use.  In most
 * cases, firmware that uses AMD's VSA code will claim all timers during
 * bootup; we certainly don't want to take them if they're already in use.
 * In other cases (such as with VSAless OpenFirmware), the system firmware
 * leaves timers available for us to use.
 */
static int scan_timers(struct cs5535_mfgpt_chip *mfgpt)
{ … }

static int cs5535_mfgpt_probe(struct platform_device *pdev)
{ … }

static struct platform_driver cs5535_mfgpt_driver = …;


static int __init cs5535_mfgpt_init(void)
{ … }

module_init(…) …;

MODULE_AUTHOR(…) …;
MODULE_DESCRIPTION(…) …;
MODULE_LICENSE(…) …;
MODULE_ALIAS(…) …;