This commit was manufactured by cvs2svn to create branch 'vserver'.

[linux-2.6.git] / drivers / clocksource / acpi_pm.c

diff --git a/drivers/clocksource/acpi_pm.c b/drivers/clocksource/acpi_pm.c
new file mode 100644 (file)
index 0000000..7ad3be8
--- /dev/null
+++ b/drivers/clocksource/acpi_pm.c
@@ -0,0 +1,177 @@
+/*
+ * linux/drivers/clocksource/acpi_pm.c
+ *
+ * This file contains the ACPI PM based clocksource.
+ *
+ * This code was largely moved from the i386 timer_pm.c file
+ * which was (C) Dominik Brodowski <linux@brodo.de> 2003
+ * and contained the following comments:
+ *
+ * Driver to use the Power Management Timer (PMTMR) available in some
+ * southbridges as primary timing source for the Linux kernel.
+ *
+ * Based on parts of linux/drivers/acpi/hardware/hwtimer.c, timer_pit.c,
+ * timer_hpet.c, and on Arjan van de Ven's implementation for 2.4.
+ *
+ * This file is licensed under the GPL v2.
+ */
+
+#include <linux/clocksource.h>
+#include <linux/errno.h>
+#include <linux/init.h>
+#include <linux/pci.h>
+#include <asm/io.h>
+
+/* Number of PMTMR ticks expected during calibration run */
+#define PMTMR_TICKS_PER_SEC 3579545
+
+/*
+ * The I/O port the PMTMR resides at.
+ * The location is detected during setup_arch(),
+ * in arch/i386/acpi/boot.c
+ */
+u32 pmtmr_ioport __read_mostly;
+
+#define ACPI_PM_MASK CLOCKSOURCE_MASK(24) /* limit it to 24 bits */
+
+static inline u32 read_pmtmr(void)
+{
+       /* mask the output to 24 bits */
+       return inl(pmtmr_ioport) & ACPI_PM_MASK;
+}
+
+static cycle_t acpi_pm_read_verified(void)
+{
+       u32 v1 = 0, v2 = 0, v3 = 0;
+
+       /*
+        * It has been reported that because of various broken
+        * chipsets (ICH4, PIIX4 and PIIX4E) where the ACPI PM clock
+        * source is not latched, you must read it multiple
+        * times to ensure a safe value is read:
+        */
+       do {
+               v1 = read_pmtmr();
+               v2 = read_pmtmr();
+               v3 = read_pmtmr();
+       } while ((v1 > v2 && v1 < v3) || (v2 > v3 && v2 < v1)
+                       || (v3 > v1 && v3 < v2));
+
+       return (cycle_t)v2;
+}
+
+static cycle_t acpi_pm_read(void)
+{
+       return (cycle_t)read_pmtmr();
+}
+
+static struct clocksource clocksource_acpi_pm = {
+       .name           = "acpi_pm",
+       .rating         = 200,
+       .read           = acpi_pm_read,
+       .mask           = (cycle_t)ACPI_PM_MASK,
+       .mult           = 0, /*to be caluclated*/
+       .shift          = 22,
+       .is_continuous  = 1,
+};
+
+
+#ifdef CONFIG_PCI
+static int acpi_pm_good;
+static int __init acpi_pm_good_setup(char *__str)
+{
+       acpi_pm_good = 1;
+       return 1;
+}
+__setup("acpi_pm_good", acpi_pm_good_setup);
+
+static inline void acpi_pm_need_workaround(void)
+{
+       clocksource_acpi_pm.read = acpi_pm_read_verified;
+       clocksource_acpi_pm.rating = 110;
+}
+
+/*
+ * PIIX4 Errata:
+ *
+ * The power management timer may return improper results when read.
+ * Although the timer value settles properly after incrementing,
+ * while incrementing there is a 3 ns window every 69.8 ns where the
+ * timer value is indeterminate (a 4.2% chance that the data will be
+ * incorrect when read). As a result, the ACPI free running count up
+ * timer specification is violated due to erroneous reads.
+ */
+static void __devinit acpi_pm_check_blacklist(struct pci_dev *dev)
+{
+       u8 rev;
+
+       if (acpi_pm_good)
+               return;
+
+       pci_read_config_byte(dev, PCI_REVISION_ID, &rev);
+       /* the bug has been fixed in PIIX4M */
+       if (rev < 3) {
+               printk(KERN_WARNING "* Found PM-Timer Bug on the chipset."
+                      " Due to workarounds for a bug,\n"
+                      "* this clock source is slow. Consider trying"
+                      " other clock sources\n");
+
+               acpi_pm_need_workaround();
+       }
+}
+DECLARE_PCI_FIXUP_EARLY(PCI_VENDOR_ID_INTEL, PCI_DEVICE_ID_INTEL_82371AB_3,
+                       acpi_pm_check_blacklist);
+
+static void __devinit acpi_pm_check_graylist(struct pci_dev *dev)
+{
+       if (acpi_pm_good)
+               return;
+
+       printk(KERN_WARNING "* The chipset may have PM-Timer Bug. Due to"
+              " workarounds for a bug,\n"
+              "* this clock source is slow. If you are sure your timer"
+              " does not have\n"
+              "* this bug, please use \"acpi_pm_good\" to disable the"
+              " workaround\n");
+
+       acpi_pm_need_workaround();
+}
+DECLARE_PCI_FIXUP_EARLY(PCI_VENDOR_ID_INTEL, PCI_DEVICE_ID_INTEL_82801DB_0,
+                       acpi_pm_check_graylist);
+#endif
+
+
+static int __init init_acpi_pm_clocksource(void)
+{
+       u32 value1, value2;
+       unsigned int i;
+
+       if (!pmtmr_ioport)
+               return -ENODEV;
+
+       clocksource_acpi_pm.mult = clocksource_hz2mult(PMTMR_TICKS_PER_SEC,
+                                               clocksource_acpi_pm.shift);
+
+       /* "verify" this timing source: */
+       value1 = read_pmtmr();
+       for (i = 0; i < 10000; i++) {
+               value2 = read_pmtmr();
+               if (value2 == value1)
+                       continue;
+               if (value2 > value1)
+                       goto pm_good;
+               if ((value2 < value1) && ((value2) < 0xFFF))
+                       goto pm_good;
+               printk(KERN_INFO "PM-Timer had inconsistent results:"
+                       " 0x%#x, 0x%#x - aborting.\n", value1, value2);
+               return -EINVAL;
+       }
+       printk(KERN_INFO "PM-Timer had no reasonable result:"
+                       " 0x%#x - aborting.\n", value1);
+       return -ENODEV;
+
+pm_good:
+       return clocksource_register(&clocksource_acpi_pm);
+}
+
+module_init(init_acpi_pm_clocksource);