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