summaryrefslogtreecommitdiffstats
path: root/drivers/misc/cs5535-mfgpt.c
diff options
context:
space:
mode:
Diffstat (limited to 'drivers/misc/cs5535-mfgpt.c')
-rw-r--r--drivers/misc/cs5535-mfgpt.c380
1 files changed, 380 insertions, 0 deletions
diff --git a/drivers/misc/cs5535-mfgpt.c b/drivers/misc/cs5535-mfgpt.c
new file mode 100644
index 0000000000..18fc1aaa5c
--- /dev/null
+++ b/drivers/misc/cs5535-mfgpt.c
@@ -0,0 +1,380 @@
+// 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 <dilinger@debian.org>
+ * Copyright (C) 2009 Andres Salomon <dilinger@collabora.co.uk>
+ *
+ * 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 "cs5535-mfgpt"
+
+static int mfgpt_reset_timers;
+module_param_named(mfgptfix, mfgpt_reset_timers, int, 0644);
+MODULE_PARM_DESC(mfgptfix, "Try to reset the MFGPT timers during init; "
+ "required by some broken BIOSes (ie, TinyBIOS < 0.99) or kexec "
+ "(1 = reset the MFGPT using an undocumented bit, "
+ "2 = perform a soft reset by unconfiguring all timers); "
+ "use what works best for you.");
+
+struct cs5535_mfgpt_timer {
+ struct cs5535_mfgpt_chip *chip;
+ int nr;
+};
+
+static struct cs5535_mfgpt_chip {
+ DECLARE_BITMAP(avail, MFGPT_MAX_TIMERS);
+ resource_size_t base;
+
+ struct platform_device *pdev;
+ spinlock_t lock;
+ int initialized;
+} cs5535_mfgpt_chip;
+
+int cs5535_mfgpt_toggle_event(struct cs5535_mfgpt_timer *timer, int cmp,
+ int event, int enable)
+{
+ uint32_t msr, mask, value, dummy;
+ int shift = (cmp == MFGPT_CMP1) ? 0 : 8;
+
+ if (!timer) {
+ WARN_ON(1);
+ 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->nr + 24);
+ break;
+
+ case MFGPT_EVENT_NMI:
+ msr = MSR_MFGPT_NR;
+ mask = 1 << (timer->nr + shift);
+ break;
+
+ case MFGPT_EVENT_IRQ:
+ msr = MSR_MFGPT_IRQ;
+ mask = 1 << (timer->nr + 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(cs5535_mfgpt_toggle_event);
+
+int cs5535_mfgpt_set_irq(struct cs5535_mfgpt_timer *timer, int cmp, int *irq,
+ int enable)
+{
+ uint32_t zsel, lpc, dummy;
+ int shift;
+
+ if (!timer) {
+ WARN_ON(1);
+ 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->nr % 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 = CONFIG_CS5535_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 (cs5535_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;
+}
+EXPORT_SYMBOL_GPL(cs5535_mfgpt_set_irq);
+
+struct cs5535_mfgpt_timer *cs5535_mfgpt_alloc_timer(int timer_nr, int domain)
+{
+ struct cs5535_mfgpt_chip *mfgpt = &cs5535_mfgpt_chip;
+ struct cs5535_mfgpt_timer *timer = NULL;
+ unsigned long flags;
+ int max;
+
+ if (!mfgpt->initialized)
+ goto done;
+
+ /* only allocate timers from the working domain if requested */
+ if (domain == MFGPT_DOMAIN_WORKING)
+ max = 6;
+ else
+ max = MFGPT_MAX_TIMERS;
+
+ if (timer_nr >= max) {
+ /* programmer error. silly programmers! */
+ WARN_ON(1);
+ goto done;
+ }
+
+ spin_lock_irqsave(&mfgpt->lock, flags);
+ if (timer_nr < 0) {
+ unsigned long t;
+
+ /* try to find any available timer */
+ t = find_first_bit(mfgpt->avail, max);
+ /* set timer_nr to -1 if no timers available */
+ timer_nr = t < max ? (int) t : -1;
+ } else {
+ /* check if the requested timer's available */
+ if (!test_bit(timer_nr, mfgpt->avail))
+ timer_nr = -1;
+ }
+
+ if (timer_nr >= 0)
+ /* if timer_nr is not -1, it's an available timer */
+ __clear_bit(timer_nr, mfgpt->avail);
+ spin_unlock_irqrestore(&mfgpt->lock, flags);
+
+ if (timer_nr < 0)
+ goto done;
+
+ timer = kmalloc(sizeof(*timer), GFP_KERNEL);
+ if (!timer) {
+ /* aw hell */
+ spin_lock_irqsave(&mfgpt->lock, flags);
+ __set_bit(timer_nr, mfgpt->avail);
+ spin_unlock_irqrestore(&mfgpt->lock, flags);
+ goto done;
+ }
+ timer->chip = mfgpt;
+ timer->nr = timer_nr;
+ dev_info(&mfgpt->pdev->dev, "registered timer %d\n", timer_nr);
+
+done:
+ return timer;
+}
+EXPORT_SYMBOL_GPL(cs5535_mfgpt_alloc_timer);
+
+/*
+ * 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)
+{
+ unsigned long flags;
+ uint16_t val;
+
+ /* timer can be made available again only if never set up */
+ val = cs5535_mfgpt_read(timer, MFGPT_REG_SETUP);
+ if (!(val & MFGPT_SETUP_SETUP)) {
+ spin_lock_irqsave(&timer->chip->lock, flags);
+ __set_bit(timer->nr, timer->chip->avail);
+ spin_unlock_irqrestore(&timer->chip->lock, flags);
+ }
+
+ kfree(timer);
+}
+EXPORT_SYMBOL_GPL(cs5535_mfgpt_free_timer);
+
+uint16_t cs5535_mfgpt_read(struct cs5535_mfgpt_timer *timer, uint16_t reg)
+{
+ return inw(timer->chip->base + reg + (timer->nr * 8));
+}
+EXPORT_SYMBOL_GPL(cs5535_mfgpt_read);
+
+void cs5535_mfgpt_write(struct cs5535_mfgpt_timer *timer, uint16_t reg,
+ uint16_t value)
+{
+ outw(value, timer->chip->base + reg + (timer->nr * 8));
+}
+EXPORT_SYMBOL_GPL(cs5535_mfgpt_write);
+
+/*
+ * 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)
+{
+ uint32_t val, dummy;
+
+ /* The following undocumented bit resets the MFGPT timers */
+ val = 0xFF; dummy = 0;
+ wrmsr(MSR_MFGPT_SETUP, val, dummy);
+}
+
+/*
+ * 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)
+{
+ int i;
+ struct cs5535_mfgpt_timer t;
+
+ for (i = 0; i < MFGPT_MAX_TIMERS; i++) {
+ t.nr = i;
+
+ cs5535_mfgpt_toggle_event(&t, MFGPT_CMP1, MFGPT_EVENT_RESET, 0);
+ cs5535_mfgpt_toggle_event(&t, MFGPT_CMP2, MFGPT_EVENT_RESET, 0);
+ cs5535_mfgpt_toggle_event(&t, MFGPT_CMP1, MFGPT_EVENT_NMI, 0);
+ cs5535_mfgpt_toggle_event(&t, MFGPT_CMP2, MFGPT_EVENT_NMI, 0);
+ cs5535_mfgpt_toggle_event(&t, MFGPT_CMP1, MFGPT_EVENT_IRQ, 0);
+ cs5535_mfgpt_toggle_event(&t, MFGPT_CMP2, MFGPT_EVENT_IRQ, 0);
+ }
+}
+
+/*
+ * 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)
+{
+ struct cs5535_mfgpt_timer timer = { .chip = mfgpt };
+ unsigned long flags;
+ int timers = 0;
+ uint16_t val;
+ int i;
+
+ /* bios workaround */
+ if (mfgpt_reset_timers == 1)
+ reset_all_timers();
+ else if (mfgpt_reset_timers == 2)
+ soft_reset();
+
+ /* just to be safe, protect this section w/ lock */
+ spin_lock_irqsave(&mfgpt->lock, flags);
+ for (i = 0; i < MFGPT_MAX_TIMERS; i++) {
+ timer.nr = i;
+ val = cs5535_mfgpt_read(&timer, MFGPT_REG_SETUP);
+ if (!(val & MFGPT_SETUP_SETUP) || mfgpt_reset_timers == 2) {
+ __set_bit(i, mfgpt->avail);
+ timers++;
+ }
+ }
+ spin_unlock_irqrestore(&mfgpt->lock, flags);
+
+ return timers;
+}
+
+static int cs5535_mfgpt_probe(struct platform_device *pdev)
+{
+ struct resource *res;
+ int err = -EIO, t;
+
+ if (mfgpt_reset_timers < 0 || mfgpt_reset_timers > 2) {
+ dev_err(&pdev->dev, "Bad mfgpt_reset_timers value: %i\n",
+ mfgpt_reset_timers);
+ goto done;
+ }
+
+ /* There are two ways to get the MFGPT base address; one is by
+ * fetching it from MSR_LBAR_MFGPT, the other is by reading the
+ * PCI BAR info. The latter method is easier (especially across
+ * different architectures), so we'll stick with that for now. If
+ * it turns out to be unreliable in the face of crappy BIOSes, we
+ * can always go back to using MSRs.. */
+
+ res = platform_get_resource(pdev, IORESOURCE_IO, 0);
+ if (!res) {
+ dev_err(&pdev->dev, "can't fetch device resource info\n");
+ goto done;
+ }
+
+ if (!request_region(res->start, resource_size(res), pdev->name)) {
+ dev_err(&pdev->dev, "can't request region\n");
+ goto done;
+ }
+
+ /* set up the driver-specific struct */
+ cs5535_mfgpt_chip.base = res->start;
+ cs5535_mfgpt_chip.pdev = pdev;
+ spin_lock_init(&cs5535_mfgpt_chip.lock);
+
+ dev_info(&pdev->dev, "reserved resource region %pR\n", res);
+
+ /* detect the available timers */
+ t = scan_timers(&cs5535_mfgpt_chip);
+ dev_info(&pdev->dev, "%d MFGPT timers available\n", t);
+ cs5535_mfgpt_chip.initialized = 1;
+ return 0;
+
+done:
+ return err;
+}
+
+static struct platform_driver cs5535_mfgpt_driver = {
+ .driver = {
+ .name = DRV_NAME,
+ },
+ .probe = cs5535_mfgpt_probe,
+};
+
+
+static int __init cs5535_mfgpt_init(void)
+{
+ return platform_driver_register(&cs5535_mfgpt_driver);
+}
+
+module_init(cs5535_mfgpt_init);
+
+MODULE_AUTHOR("Andres Salomon <dilinger@queued.net>");
+MODULE_DESCRIPTION("CS5535/CS5536 MFGPT timer driver");
+MODULE_LICENSE("GPL");
+MODULE_ALIAS("platform:" DRV_NAME);
generated by cgit v1.2.3 (git 2.39.1) at 2024-11-06 07:31:37 +0000