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Diffstat (limited to 'arch/x86/kernel/mfgpt_32.c')
| -rw-r--r-- | arch/x86/kernel/mfgpt_32.c | 197 |
1 files changed, 197 insertions, 0 deletions
diff --git a/arch/x86/kernel/mfgpt_32.c b/arch/x86/kernel/mfgpt_32.c new file mode 100644 index 00000000000..3a63a2dd8d2 --- /dev/null +++ b/arch/x86/kernel/mfgpt_32.c @@ -0,0 +1,197 @@ +/* + * 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 32Khz input clock - its 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 32000 .0005 2.048 + * 2 16000 .001 4.096 + * 4 8000 .002 8.192 + * 8 4000 .004 16.384 + * 16 2000 .008 32.768 + * 32 1000 .016 65.536 + * 64 500 .032 131.072 + * 128 250 .064 262.144 + * 256 125 .128 524.288 + */ + +#include <linux/kernel.h> +#include <linux/interrupt.h> +#include <linux/module.h> +#include <asm/geode.h> + +#define F_AVAIL 0x01 + +static struct mfgpt_timer_t { + int flags; + struct module *owner; +} mfgpt_timers[MFGPT_MAX_TIMERS]; + +/* Selected from the table above */ + +#define MFGPT_DIVISOR 16 +#define MFGPT_SCALE 4 /* divisor = 2^(scale) */ +#define MFGPT_HZ (32000 / 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); + +/* + * 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. + */ +int __init geode_mfgpt_detect(void) +{ + int count = 0, i; + u16 val; + + if (disable) { + printk(KERN_INFO "geode-mfgpt: Skipping MFGPT setup\n"); + return 0; + } + + for (i = 0; i < MFGPT_MAX_TIMERS; i++) { + val = geode_mfgpt_read(i, MFGPT_REG_SETUP); + if (!(val & MFGPT_SETUP_SETUP)) { + mfgpt_timers[i].flags = F_AVAIL; + count++; + } + } + + return count; +} + +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 = MFGPT_NR_MSR; + mask = 1 << (timer + 24); + break; + + case MFGPT_EVENT_NMI: + msr = MFGPT_NR_MSR; + mask = 1 << (timer + shift); + break; + + case MFGPT_EVENT_IRQ: + msr = MFGPT_IRQ_MSR; + 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; +} + +int geode_mfgpt_set_irq(int timer, int cmp, int irq, int enable) +{ + u32 val, dummy; + int offset; + + if (timer < 0 || timer >= MFGPT_MAX_TIMERS) + return -EIO; + + if (geode_mfgpt_toggle_event(timer, cmp, MFGPT_EVENT_IRQ, enable)) + return -EIO; + + rdmsr(MSR_PIC_ZSEL_LOW, val, dummy); + + offset = (timer % 4) * 4; + + val &= ~((0xF << offset) | (0xF << (offset + 16))); + + if (enable) { + val |= (irq & 0x0F) << (offset); + val |= (irq & 0x0F) << (offset + 16); + } + + wrmsr(MSR_PIC_ZSEL_LOW, val, dummy); + return 0; +} + +static int mfgpt_get(int timer, struct module *owner) +{ + mfgpt_timers[timer].flags &= ~F_AVAIL; + mfgpt_timers[timer].owner = owner; + printk(KERN_INFO "geode-mfgpt: Registered timer %d\n", timer); + return timer; +} + +int geode_mfgpt_alloc_timer(int timer, int domain, struct module *owner) +{ + int i; + + if (!geode_get_dev_base(GEODE_DEV_MFGPT)) + return -ENODEV; + if (timer >= MFGPT_MAX_TIMERS) + return -EIO; + + if (timer < 0) { + /* Try to find an available timer */ + for (i = 0; i < MFGPT_MAX_TIMERS; i++) { + if (mfgpt_timers[i].flags & F_AVAIL) + return mfgpt_get(i, owner); + + if (i == 5 && domain == MFGPT_DOMAIN_WORKING) + break; + } + } else { + /* If they requested a specific timer, try to honor that */ + if (mfgpt_timers[timer].flags & F_AVAIL) + return mfgpt_get(timer, owner); + } + + /* No timers available - too bad */ + return -1; +} + |