cs5535: add a generic MFGPT driver

This is based on the old code on arch/x86/kernel/mfgpt_32.c, except it's
not x86 specific, it's modular, and it makes use of a PCI BAR rather than
a random MSR.  Currently module unloading is not supported; it's uncertain
whether or not it can be made work with the hardware.

[akpm@linux-foundation.org: add X86 dependency]
Signed-off-by: Andres Salomon <dilinger@collabora.co.uk>
Cc: Jordan Crouse <jordan@cosmicpenguin.net>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: john stultz <johnstul@us.ibm.com>
Cc: Chris Ball <cjb@laptop.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

3 files changed, 395 insertions, 0 deletions

diff --git a/drivers/misc/Kconfig b/drivers/misc/Kconfig
index 724d1188a322..d6d6d846f0d6 100644
--- a/drivers/misc/Kconfig
+++ b/drivers/misc/Kconfig
@@ -187,6 +187,30 @@ config SGI_XP
           this feature will allow for direct communication between SSIs
           based on a network adapter and DMA messaging.
 
+config CS5535_MFGPT
+        tristate "CS5535/CS5536 Geode Multi-Function General Purpose Timer (MFGPT) support"
+        depends on PCI && !MGEODE_LX
+        depends on X86
+        default n
+        help
+          This driver provides access to MFGPT functionality for other
+          drivers that need timers.  MFGPTs are available in the CS5535 and
+          CS5536 companion chips that are found in AMD Geode and several
+          other platforms.  They have a better resolution and max interval
+          than the generic PIT, and are suitable for use as high-res timers.
+          You probably don't want to enable this manually; other drivers that
+          make use of it should enable it.
+
+config CS5535_MFGPT_DEFAULT_IRQ
+        int
+        default 7
+        help
+          MFGPTs on the CS5535 require an interrupt.  The selected IRQ
+          can be overridden as a module option as well as by driver that
+          use the cs5535_mfgpt_ API; however, different architectures might
+          want to use a different IRQ by default.  This is here for
+          architectures to set as necessary.
+
 config HP_ILO
         tristate "Channel interface driver for HP iLO/iLO2 processor"
         depends on PCI
diff --git a/drivers/misc/Makefile b/drivers/misc/Makefile
index e76b77977442..049ff2482f30 100644
--- a/drivers/misc/Makefile
+++ b/drivers/misc/Makefile
@@ -18,6 +18,7 @@ obj-$(CONFIG_ENCLOSURE_SERVICES) += enclosure.o
 obj-$(CONFIG_KGDB_TESTS)        += kgdbts.o
 obj-$(CONFIG_SGI_XP)            += sgi-xp/
 obj-$(CONFIG_SGI_GRU)           += sgi-gru/
+obj-$(CONFIG_CS5535_MFGPT)      += cs5535-mfgpt.o
 obj-$(CONFIG_HP_ILO)            += hpilo.o
 obj-$(CONFIG_ISL29003)          += isl29003.o
 obj-$(CONFIG_EP93XX_PWM)        += ep93xx_pwm.o
diff --git a/drivers/misc/cs5535-mfgpt.c b/drivers/misc/cs5535-mfgpt.c
new file mode 100644
index 000000000000..8110460558ff
--- /dev/null
+++ b/drivers/misc/cs5535-mfgpt.c
@@ -0,0 +1,370 @@
+/*
+ * 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>
+ *
+ * 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.
+ */
+
+#include <linux/kernel.h>
+#include <linux/spinlock.h>
+#include <linux/interrupt.h>
+#include <linux/module.h>
+#include <linux/pci.h>
+#include <linux/cs5535.h>
+
+#define DRV_NAME "cs5535-mfgpt"
+#define MFGPT_BAR 2
+
+static int mfgpt_reset_timers;
+module_param_named(mfgptfix, mfgpt_reset_timers, int, 0644);
+MODULE_PARM_DESC(mfgptfix, "Reset the MFGPT timers during init; "
+                "required by some broken BIOSes (ie, TinyBIOS < 0.99).");
+
+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 pci_dev *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)
+{
+        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 __init 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);
+}
+
+/*
+ * 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 __init 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)
+                reset_all_timers();
+
+        /* 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)) {
+                        __set_bit(i, mfgpt->avail);
+                        timers++;
+                }
+        }
+        spin_unlock_irqrestore(&mfgpt->lock, flags);
+
+        return timers;
+}
+
+static int __init cs5535_mfgpt_probe(struct pci_dev *pdev,
+                const struct pci_device_id *pci_id)
+{
+        int err, t;
+
+        /* 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.. */
+
+        err = pci_enable_device_io(pdev);
+        if (err) {
+                dev_err(&pdev->dev, "can't enable device IO\n");
+                goto done;
+        }
+
+        err = pci_request_region(pdev, MFGPT_BAR, DRV_NAME);
+        if (err) {
+                dev_err(&pdev->dev, "can't alloc PCI BAR #%d\n", MFGPT_BAR);
+                goto done;
+        }
+
+        /* set up the driver-specific struct */
+        cs5535_mfgpt_chip.base = pci_resource_start(pdev, MFGPT_BAR);
+        cs5535_mfgpt_chip.pdev = pdev;
+        spin_lock_init(&cs5535_mfgpt_chip.lock);
+
+        dev_info(&pdev->dev, "allocated PCI BAR #%d: base 0x%llx\n", MFGPT_BAR,
+                        (unsigned long long) cs5535_mfgpt_chip.base);
+
+        /* detect the available timers */
+        t = scan_timers(&cs5535_mfgpt_chip);
+        dev_info(&pdev->dev, DRV_NAME ": %d MFGPT timers available\n", t);
+        cs5535_mfgpt_chip.initialized = 1;
+        return 0;
+
+done:
+        return err;
+}
+
+static struct pci_device_id cs5535_mfgpt_pci_tbl[] = {
+        { PCI_DEVICE(PCI_VENDOR_ID_NS, PCI_DEVICE_ID_NS_CS5535_ISA) },
+        { PCI_DEVICE(PCI_VENDOR_ID_AMD, PCI_DEVICE_ID_AMD_CS5536_ISA) },
+        { 0, },
+};
+MODULE_DEVICE_TABLE(pci, cs5535_mfgpt_pci_tbl);
+
+/*
+ * Just like with the cs5535-gpio driver, we can't use the standard PCI driver
+ * registration stuff.  It only allows only one driver to bind to each PCI
+ * device, and we want the GPIO and MFGPT drivers to be able to share a PCI
+ * device.  Instead, we manually scan for the PCI device, request a single
+ * region, and keep track of the devices that we're using.
+ */
+
+static int __init cs5535_mfgpt_scan_pci(void)
+{
+        struct pci_dev *pdev;
+        int err = -ENODEV;
+        int i;
+
+        for (i = 0; i < ARRAY_SIZE(cs5535_mfgpt_pci_tbl); i++) {
+                pdev = pci_get_device(cs5535_mfgpt_pci_tbl[i].vendor,
+                                cs5535_mfgpt_pci_tbl[i].device, NULL);
+                if (pdev) {
+                        err = cs5535_mfgpt_probe(pdev,
+                                        &cs5535_mfgpt_pci_tbl[i]);
+                        if (err)
+                                pci_dev_put(pdev);
+
+                        /* we only support a single CS5535/6 southbridge */
+                        break;
+                }
+        }
+
+        return err;
+}
+
+static int __init cs5535_mfgpt_init(void)
+{
+        return cs5535_mfgpt_scan_pci();
+}
+
+module_init(cs5535_mfgpt_init);
+
+MODULE_AUTHOR("Andres Salomon <dilinger@collabora.co.uk>");
+MODULE_DESCRIPTION("CS5535/CS5536 MFGPT timer driver");
+MODULE_LICENSE("GPL");