412 lines
10 KiB
C
412 lines
10 KiB
C
/*
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* Driver/API for AMD Geode Multi-Function General Purpose Timers (MFGPT)
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*
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* Copyright (C) 2006, Advanced Micro Devices, Inc.
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* Copyright (C) 2007, Andres Salomon <dilinger@debian.org>
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of version 2 of the GNU General Public License
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* as published by the Free Software Foundation.
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*
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* The MFGPTs are documented in AMD Geode CS5536 Companion Device Data Book.
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*/
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/*
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* We are using the 32.768kHz input clock - it's the only one that has the
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* ranges we find desirable. The following table lists the suitable
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* divisors and the associated Hz, minimum interval and the maximum interval:
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*
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* Divisor Hz Min Delta (s) Max Delta (s)
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* 1 32768 .00048828125 2.000
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* 2 16384 .0009765625 4.000
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* 4 8192 .001953125 8.000
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* 8 4096 .00390625 16.000
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* 16 2048 .0078125 32.000
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* 32 1024 .015625 64.000
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* 64 512 .03125 128.000
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* 128 256 .0625 256.000
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* 256 128 .125 512.000
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*/
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#include <linux/kernel.h>
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#include <linux/interrupt.h>
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#include <linux/module.h>
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#include <asm/geode.h>
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#define MFGPT_DEFAULT_IRQ 7
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static struct mfgpt_timer_t {
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unsigned int avail:1;
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} mfgpt_timers[MFGPT_MAX_TIMERS];
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/* Selected from the table above */
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#define MFGPT_DIVISOR 16
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#define MFGPT_SCALE 4 /* divisor = 2^(scale) */
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#define MFGPT_HZ (32768 / MFGPT_DIVISOR)
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#define MFGPT_PERIODIC (MFGPT_HZ / HZ)
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/* Allow for disabling of MFGPTs */
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static int disable;
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static int __init mfgpt_disable(char *s)
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{
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disable = 1;
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return 1;
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}
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__setup("nomfgpt", mfgpt_disable);
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/* Reset the MFGPT timers. This is required by some broken BIOSes which already
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* do the same and leave the system in an unstable state. TinyBIOS 0.98 is
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* affected at least (0.99 is OK with MFGPT workaround left to off).
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*/
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static int __init mfgpt_fix(char *s)
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{
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u32 val, dummy;
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/* The following udocumented bit resets the MFGPT timers */
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val = 0xFF; dummy = 0;
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wrmsr(MSR_MFGPT_SETUP, val, dummy);
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return 1;
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}
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__setup("mfgptfix", mfgpt_fix);
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/*
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* Check whether any MFGPTs are available for the kernel to use. In most
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* cases, firmware that uses AMD's VSA code will claim all timers during
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* bootup; we certainly don't want to take them if they're already in use.
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* In other cases (such as with VSAless OpenFirmware), the system firmware
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* leaves timers available for us to use.
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*/
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static int timers = -1;
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static void geode_mfgpt_detect(void)
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{
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int i;
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u16 val;
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timers = 0;
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if (disable) {
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printk(KERN_INFO "geode-mfgpt: MFGPT support is disabled\n");
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goto done;
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}
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if (!geode_get_dev_base(GEODE_DEV_MFGPT)) {
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printk(KERN_INFO "geode-mfgpt: MFGPT LBAR is not set up\n");
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goto done;
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}
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for (i = 0; i < MFGPT_MAX_TIMERS; i++) {
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val = geode_mfgpt_read(i, MFGPT_REG_SETUP);
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if (!(val & MFGPT_SETUP_SETUP)) {
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mfgpt_timers[i].avail = 1;
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timers++;
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}
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}
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done:
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printk(KERN_INFO "geode-mfgpt: %d MFGPT timers available.\n", timers);
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}
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int geode_mfgpt_toggle_event(int timer, int cmp, int event, int enable)
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{
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u32 msr, mask, value, dummy;
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int shift = (cmp == MFGPT_CMP1) ? 0 : 8;
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if (timer < 0 || timer >= MFGPT_MAX_TIMERS)
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return -EIO;
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/*
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* The register maps for these are described in sections 6.17.1.x of
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* the AMD Geode CS5536 Companion Device Data Book.
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*/
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switch (event) {
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case MFGPT_EVENT_RESET:
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/*
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* XXX: According to the docs, we cannot reset timers above
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* 6; that is, resets for 7 and 8 will be ignored. Is this
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* a problem? -dilinger
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*/
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msr = MSR_MFGPT_NR;
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mask = 1 << (timer + 24);
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break;
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case MFGPT_EVENT_NMI:
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msr = MSR_MFGPT_NR;
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mask = 1 << (timer + shift);
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break;
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case MFGPT_EVENT_IRQ:
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msr = MSR_MFGPT_IRQ;
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mask = 1 << (timer + shift);
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break;
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default:
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return -EIO;
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}
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rdmsr(msr, value, dummy);
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if (enable)
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value |= mask;
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else
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value &= ~mask;
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wrmsr(msr, value, dummy);
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return 0;
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}
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EXPORT_SYMBOL_GPL(geode_mfgpt_toggle_event);
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int geode_mfgpt_set_irq(int timer, int cmp, int *irq, int enable)
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{
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u32 zsel, lpc, dummy;
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int shift;
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if (timer < 0 || timer >= MFGPT_MAX_TIMERS)
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return -EIO;
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/*
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* Unfortunately, MFGPTs come in pairs sharing their IRQ lines. If VSA
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* is using the same CMP of the timer's Siamese twin, the IRQ is set to
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* 2, and we mustn't use nor change it.
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* XXX: Likewise, 2 Linux drivers might clash if the 2nd overwrites the
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* IRQ of the 1st. This can only happen if forcing an IRQ, calling this
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* with *irq==0 is safe. Currently there _are_ no 2 drivers.
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*/
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rdmsr(MSR_PIC_ZSEL_LOW, zsel, dummy);
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shift = ((cmp == MFGPT_CMP1 ? 0 : 4) + timer % 4) * 4;
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if (((zsel >> shift) & 0xF) == 2)
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return -EIO;
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/* Choose IRQ: if none supplied, keep IRQ already set or use default */
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if (!*irq)
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*irq = (zsel >> shift) & 0xF;
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if (!*irq)
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*irq = MFGPT_DEFAULT_IRQ;
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/* Can't use IRQ if it's 0 (=disabled), 2, or routed to LPC */
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if (*irq < 1 || *irq == 2 || *irq > 15)
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return -EIO;
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rdmsr(MSR_PIC_IRQM_LPC, lpc, dummy);
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if (lpc & (1 << *irq))
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return -EIO;
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/* All chosen and checked - go for it */
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if (geode_mfgpt_toggle_event(timer, cmp, MFGPT_EVENT_IRQ, enable))
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return -EIO;
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if (enable) {
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zsel = (zsel & ~(0xF << shift)) | (*irq << shift);
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wrmsr(MSR_PIC_ZSEL_LOW, zsel, dummy);
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}
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return 0;
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}
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static int mfgpt_get(int timer)
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{
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mfgpt_timers[timer].avail = 0;
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printk(KERN_INFO "geode-mfgpt: Registered timer %d\n", timer);
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return timer;
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}
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int geode_mfgpt_alloc_timer(int timer, int domain)
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{
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int i;
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if (timers == -1) {
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/* timers haven't been detected yet */
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geode_mfgpt_detect();
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}
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if (!timers)
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return -1;
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if (timer >= MFGPT_MAX_TIMERS)
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return -1;
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if (timer < 0) {
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/* Try to find an available timer */
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for (i = 0; i < MFGPT_MAX_TIMERS; i++) {
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if (mfgpt_timers[i].avail)
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return mfgpt_get(i);
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if (i == 5 && domain == MFGPT_DOMAIN_WORKING)
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break;
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}
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} else {
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/* If they requested a specific timer, try to honor that */
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if (mfgpt_timers[timer].avail)
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return mfgpt_get(timer);
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}
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/* No timers available - too bad */
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return -1;
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}
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EXPORT_SYMBOL_GPL(geode_mfgpt_alloc_timer);
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#ifdef CONFIG_GEODE_MFGPT_TIMER
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/*
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* The MFPGT timers on the CS5536 provide us with suitable timers to use
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* as clock event sources - not as good as a HPET or APIC, but certainly
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* better than the PIT. This isn't a general purpose MFGPT driver, but
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* a simplified one designed specifically to act as a clock event source.
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* For full details about the MFGPT, please consult the CS5536 data sheet.
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*/
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#include <linux/clocksource.h>
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#include <linux/clockchips.h>
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static unsigned int mfgpt_tick_mode = CLOCK_EVT_MODE_SHUTDOWN;
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static u16 mfgpt_event_clock;
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static int irq;
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static int __init mfgpt_setup(char *str)
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{
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get_option(&str, &irq);
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return 1;
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}
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__setup("mfgpt_irq=", mfgpt_setup);
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static void mfgpt_disable_timer(u16 clock)
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{
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/* avoid races by clearing CMP1 and CMP2 unconditionally */
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geode_mfgpt_write(clock, MFGPT_REG_SETUP, (u16) ~MFGPT_SETUP_CNTEN |
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MFGPT_SETUP_CMP1 | MFGPT_SETUP_CMP2);
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}
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static int mfgpt_next_event(unsigned long, struct clock_event_device *);
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static void mfgpt_set_mode(enum clock_event_mode, struct clock_event_device *);
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static struct clock_event_device mfgpt_clockevent = {
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.name = "mfgpt-timer",
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.features = CLOCK_EVT_FEAT_PERIODIC | CLOCK_EVT_FEAT_ONESHOT,
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.set_mode = mfgpt_set_mode,
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.set_next_event = mfgpt_next_event,
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.rating = 250,
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.cpumask = cpu_all_mask,
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.shift = 32
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};
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static void mfgpt_start_timer(u16 delta)
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{
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geode_mfgpt_write(mfgpt_event_clock, MFGPT_REG_CMP2, (u16) delta);
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geode_mfgpt_write(mfgpt_event_clock, MFGPT_REG_COUNTER, 0);
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geode_mfgpt_write(mfgpt_event_clock, MFGPT_REG_SETUP,
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MFGPT_SETUP_CNTEN | MFGPT_SETUP_CMP2);
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}
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static void mfgpt_set_mode(enum clock_event_mode mode,
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struct clock_event_device *evt)
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{
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mfgpt_disable_timer(mfgpt_event_clock);
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if (mode == CLOCK_EVT_MODE_PERIODIC)
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mfgpt_start_timer(MFGPT_PERIODIC);
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mfgpt_tick_mode = mode;
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}
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static int mfgpt_next_event(unsigned long delta, struct clock_event_device *evt)
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{
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mfgpt_start_timer(delta);
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return 0;
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}
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static irqreturn_t mfgpt_tick(int irq, void *dev_id)
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{
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u16 val = geode_mfgpt_read(mfgpt_event_clock, MFGPT_REG_SETUP);
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/* See if the interrupt was for us */
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if (!(val & (MFGPT_SETUP_SETUP | MFGPT_SETUP_CMP2 | MFGPT_SETUP_CMP1)))
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return IRQ_NONE;
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/* Turn off the clock (and clear the event) */
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mfgpt_disable_timer(mfgpt_event_clock);
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if (mfgpt_tick_mode == CLOCK_EVT_MODE_SHUTDOWN)
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return IRQ_HANDLED;
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/* Clear the counter */
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geode_mfgpt_write(mfgpt_event_clock, MFGPT_REG_COUNTER, 0);
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/* Restart the clock in periodic mode */
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if (mfgpt_tick_mode == CLOCK_EVT_MODE_PERIODIC) {
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geode_mfgpt_write(mfgpt_event_clock, MFGPT_REG_SETUP,
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MFGPT_SETUP_CNTEN | MFGPT_SETUP_CMP2);
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}
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mfgpt_clockevent.event_handler(&mfgpt_clockevent);
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return IRQ_HANDLED;
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}
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static struct irqaction mfgptirq = {
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.handler = mfgpt_tick,
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.flags = IRQF_DISABLED | IRQF_NOBALANCING,
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.mask = CPU_MASK_NONE,
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.name = "mfgpt-timer"
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};
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int __init mfgpt_timer_setup(void)
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{
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int timer, ret;
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u16 val;
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timer = geode_mfgpt_alloc_timer(MFGPT_TIMER_ANY, MFGPT_DOMAIN_WORKING);
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if (timer < 0) {
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printk(KERN_ERR
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"mfgpt-timer: Could not allocate a MFPGT timer\n");
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return -ENODEV;
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}
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mfgpt_event_clock = timer;
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/* Set up the IRQ on the MFGPT side */
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if (geode_mfgpt_setup_irq(mfgpt_event_clock, MFGPT_CMP2, &irq)) {
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printk(KERN_ERR "mfgpt-timer: Could not set up IRQ %d\n", irq);
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return -EIO;
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}
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/* And register it with the kernel */
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ret = setup_irq(irq, &mfgptirq);
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if (ret) {
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printk(KERN_ERR
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"mfgpt-timer: Unable to set up the interrupt.\n");
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goto err;
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}
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/* Set the clock scale and enable the event mode for CMP2 */
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val = MFGPT_SCALE | (3 << 8);
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geode_mfgpt_write(mfgpt_event_clock, MFGPT_REG_SETUP, val);
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/* Set up the clock event */
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mfgpt_clockevent.mult = div_sc(MFGPT_HZ, NSEC_PER_SEC,
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mfgpt_clockevent.shift);
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mfgpt_clockevent.min_delta_ns = clockevent_delta2ns(0xF,
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&mfgpt_clockevent);
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mfgpt_clockevent.max_delta_ns = clockevent_delta2ns(0xFFFE,
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&mfgpt_clockevent);
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printk(KERN_INFO
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"mfgpt-timer: Registering MFGPT timer %d as a clock event, using IRQ %d\n",
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timer, irq);
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clockevents_register_device(&mfgpt_clockevent);
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return 0;
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err:
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geode_mfgpt_release_irq(mfgpt_event_clock, MFGPT_CMP2, &irq);
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printk(KERN_ERR
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"mfgpt-timer: Unable to set up the MFGPT clock source\n");
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return -EIO;
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}
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#endif
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