![David Vrabel](/assets/img/avatar_default.png)
Adding the rtc platform device in non-privileged Xen PV guests causes an IRQ conflict because these guests do not have legacy PIC and may allocate irqs in the legacy range. In a single VCPU Xen PV guest we should have: /proc/interrupts: CPU0 0: 4934 xen-percpu-virq timer0 1: 0 xen-percpu-ipi spinlock0 2: 0 xen-percpu-ipi resched0 3: 0 xen-percpu-ipi callfunc0 4: 0 xen-percpu-virq debug0 5: 0 xen-percpu-ipi callfuncsingle0 6: 0 xen-percpu-ipi irqwork0 7: 321 xen-dyn-event xenbus 8: 90 xen-dyn-event hvc_console ... But hvc_console cannot get its interrupt because it is already in use by rtc0 and the console does not work. genirq: Flags mismatch irq 8. 00000000 (hvc_console) vs. 00000000 (rtc0) We can avoid this problem by realizing that unprivileged PV guests (both Xen and lguests) are not supposed to have rtc_cmos device and so adding it is not necessary. Privileged guests (i.e. Xen's dom0) do use it but they should not have irq conflicts since they allocate irqs above legacy range (above gsi_top, in fact). Instead of explicitly testing whether the guest is privileged we can extend pv_info structure to include information about guest's RTC support. Reported-and-tested-by: Sander Eikelenboom <linux@eikelenboom.it> Signed-off-by: David Vrabel <david.vrabel@citrix.com> Signed-off-by: Boris Ostrovsky <boris.ostrovsky@oracle.com> Cc: vkuznets@redhat.com Cc: xen-devel@lists.xenproject.org Cc: konrad.wilk@oracle.com Cc: stable@vger.kernel.org # 4.2+ Link: http://lkml.kernel.org/r/1449842873-2613-1-git-send-email-boris.ostrovsky@oracle.com Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
213 lines
4.9 KiB
C
213 lines
4.9 KiB
C
/*
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* RTC related functions
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*/
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#include <linux/platform_device.h>
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#include <linux/mc146818rtc.h>
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#include <linux/acpi.h>
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#include <linux/bcd.h>
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#include <linux/export.h>
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#include <linux/pnp.h>
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#include <linux/of.h>
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#include <asm/vsyscall.h>
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#include <asm/x86_init.h>
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#include <asm/time.h>
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#include <asm/intel-mid.h>
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#include <asm/rtc.h>
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#ifdef CONFIG_X86_32
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/*
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* This is a special lock that is owned by the CPU and holds the index
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* register we are working with. It is required for NMI access to the
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* CMOS/RTC registers. See include/asm-i386/mc146818rtc.h for details.
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*/
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volatile unsigned long cmos_lock;
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EXPORT_SYMBOL(cmos_lock);
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#endif /* CONFIG_X86_32 */
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/* For two digit years assume time is always after that */
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#define CMOS_YEARS_OFFS 2000
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DEFINE_SPINLOCK(rtc_lock);
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EXPORT_SYMBOL(rtc_lock);
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/*
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* In order to set the CMOS clock precisely, set_rtc_mmss has to be
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* called 500 ms after the second nowtime has started, because when
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* nowtime is written into the registers of the CMOS clock, it will
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* jump to the next second precisely 500 ms later. Check the Motorola
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* MC146818A or Dallas DS12887 data sheet for details.
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*/
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int mach_set_rtc_mmss(const struct timespec *now)
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{
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unsigned long nowtime = now->tv_sec;
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struct rtc_time tm;
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int retval = 0;
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rtc_time_to_tm(nowtime, &tm);
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if (!rtc_valid_tm(&tm)) {
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retval = set_rtc_time(&tm);
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if (retval)
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printk(KERN_ERR "%s: RTC write failed with error %d\n",
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__func__, retval);
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} else {
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printk(KERN_ERR
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"%s: Invalid RTC value: write of %lx to RTC failed\n",
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__func__, nowtime);
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retval = -EINVAL;
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}
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return retval;
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}
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void mach_get_cmos_time(struct timespec *now)
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{
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unsigned int status, year, mon, day, hour, min, sec, century = 0;
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unsigned long flags;
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spin_lock_irqsave(&rtc_lock, flags);
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/*
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* If UIP is clear, then we have >= 244 microseconds before
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* RTC registers will be updated. Spec sheet says that this
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* is the reliable way to read RTC - registers. If UIP is set
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* then the register access might be invalid.
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*/
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while ((CMOS_READ(RTC_FREQ_SELECT) & RTC_UIP))
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cpu_relax();
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sec = CMOS_READ(RTC_SECONDS);
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min = CMOS_READ(RTC_MINUTES);
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hour = CMOS_READ(RTC_HOURS);
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day = CMOS_READ(RTC_DAY_OF_MONTH);
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mon = CMOS_READ(RTC_MONTH);
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year = CMOS_READ(RTC_YEAR);
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#ifdef CONFIG_ACPI
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if (acpi_gbl_FADT.header.revision >= FADT2_REVISION_ID &&
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acpi_gbl_FADT.century)
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century = CMOS_READ(acpi_gbl_FADT.century);
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#endif
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status = CMOS_READ(RTC_CONTROL);
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WARN_ON_ONCE(RTC_ALWAYS_BCD && (status & RTC_DM_BINARY));
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spin_unlock_irqrestore(&rtc_lock, flags);
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if (RTC_ALWAYS_BCD || !(status & RTC_DM_BINARY)) {
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sec = bcd2bin(sec);
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min = bcd2bin(min);
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hour = bcd2bin(hour);
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day = bcd2bin(day);
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mon = bcd2bin(mon);
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year = bcd2bin(year);
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}
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if (century) {
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century = bcd2bin(century);
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year += century * 100;
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} else
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year += CMOS_YEARS_OFFS;
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now->tv_sec = mktime(year, mon, day, hour, min, sec);
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now->tv_nsec = 0;
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}
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/* Routines for accessing the CMOS RAM/RTC. */
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unsigned char rtc_cmos_read(unsigned char addr)
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{
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unsigned char val;
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lock_cmos_prefix(addr);
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outb(addr, RTC_PORT(0));
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val = inb(RTC_PORT(1));
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lock_cmos_suffix(addr);
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return val;
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}
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EXPORT_SYMBOL(rtc_cmos_read);
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void rtc_cmos_write(unsigned char val, unsigned char addr)
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{
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lock_cmos_prefix(addr);
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outb(addr, RTC_PORT(0));
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outb(val, RTC_PORT(1));
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lock_cmos_suffix(addr);
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}
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EXPORT_SYMBOL(rtc_cmos_write);
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int update_persistent_clock(struct timespec now)
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{
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return x86_platform.set_wallclock(&now);
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}
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/* not static: needed by APM */
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void read_persistent_clock(struct timespec *ts)
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{
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x86_platform.get_wallclock(ts);
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}
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static struct resource rtc_resources[] = {
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[0] = {
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.start = RTC_PORT(0),
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.end = RTC_PORT(1),
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.flags = IORESOURCE_IO,
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},
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[1] = {
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.start = RTC_IRQ,
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.end = RTC_IRQ,
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.flags = IORESOURCE_IRQ,
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}
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};
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static struct platform_device rtc_device = {
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.name = "rtc_cmos",
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.id = -1,
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.resource = rtc_resources,
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.num_resources = ARRAY_SIZE(rtc_resources),
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};
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static __init int add_rtc_cmos(void)
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{
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#ifdef CONFIG_PNP
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static const char * const ids[] __initconst =
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{ "PNP0b00", "PNP0b01", "PNP0b02", };
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struct pnp_dev *dev;
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struct pnp_id *id;
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int i;
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pnp_for_each_dev(dev) {
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for (id = dev->id; id; id = id->next) {
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for (i = 0; i < ARRAY_SIZE(ids); i++) {
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if (compare_pnp_id(id, ids[i]) != 0)
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return 0;
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}
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}
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}
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#endif
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if (of_have_populated_dt())
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return 0;
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/* Intel MID platforms don't have ioport rtc */
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if (intel_mid_identify_cpu())
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return -ENODEV;
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#ifdef CONFIG_ACPI
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if (acpi_gbl_FADT.boot_flags & ACPI_FADT_NO_CMOS_RTC) {
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/* This warning can likely go away again in a year or two. */
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pr_info("ACPI: not registering RTC platform device\n");
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return -ENODEV;
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}
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#endif
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if (paravirt_enabled() && !paravirt_has(RTC))
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return -ENODEV;
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platform_device_register(&rtc_device);
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dev_info(&rtc_device.dev,
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"registered platform RTC device (no PNP device found)\n");
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return 0;
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}
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device_initcall(add_rtc_cmos);
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