drivers/char/uv_mmtimer.c: add memory mapped RTC driver for UV

This driver memory maps the UV Hub RTC.

Signed-off-by: Dimitri Sivanich <sivanich@sgi.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 216 insertions, 0 deletions

diff --git a/drivers/char/uv_mmtimer.c b/drivers/char/uv_mmtimer.c
new file mode 100644
index 00000000000..867b67be9f0
--- /dev/null
+++ b/drivers/char/uv_mmtimer.c
@@ -0,0 +1,216 @@
+/*
+ * Timer device implementation for SGI UV platform.
+ *
+ * This file is subject to the terms and conditions of the GNU General Public
+ * License.  See the file "COPYING" in the main directory of this archive
+ * for more details.
+ *
+ * Copyright (c) 2009 Silicon Graphics, Inc.  All rights reserved.
+ *
+ */
+
+#include <linux/types.h>
+#include <linux/kernel.h>
+#include <linux/ioctl.h>
+#include <linux/module.h>
+#include <linux/init.h>
+#include <linux/errno.h>
+#include <linux/mm.h>
+#include <linux/fs.h>
+#include <linux/mmtimer.h>
+#include <linux/miscdevice.h>
+#include <linux/posix-timers.h>
+#include <linux/interrupt.h>
+#include <linux/time.h>
+#include <linux/math64.h>
+#include <linux/smp_lock.h>
+
+#include <asm/genapic.h>
+#include <asm/uv/uv_hub.h>
+#include <asm/uv/bios.h>
+#include <asm/uv/uv.h>
+
+MODULE_AUTHOR("Dimitri Sivanich <sivanich@sgi.com>");
+MODULE_DESCRIPTION("SGI UV Memory Mapped RTC Timer");
+MODULE_LICENSE("GPL");
+
+/* name of the device, usually in /dev */
+#define UV_MMTIMER_NAME "mmtimer"
+#define UV_MMTIMER_DESC "SGI UV Memory Mapped RTC Timer"
+#define UV_MMTIMER_VERSION "1.0"
+
+static long uv_mmtimer_ioctl(struct file *file, unsigned int cmd,
+                                                unsigned long arg);
+static int uv_mmtimer_mmap(struct file *file, struct vm_area_struct *vma);
+
+/*
+ * Period in femtoseconds (10^-15 s)
+ */
+static unsigned long uv_mmtimer_femtoperiod;
+
+static const struct file_operations uv_mmtimer_fops = {
+        .owner = THIS_MODULE,
+        .mmap = uv_mmtimer_mmap,
+        .unlocked_ioctl = uv_mmtimer_ioctl,
+};
+
+/**
+ * uv_mmtimer_ioctl - ioctl interface for /dev/uv_mmtimer
+ * @file: file structure for the device
+ * @cmd: command to execute
+ * @arg: optional argument to command
+ *
+ * Executes the command specified by @cmd.  Returns 0 for success, < 0 for
+ * failure.
+ *
+ * Valid commands:
+ *
+ * %MMTIMER_GETOFFSET - Should return the offset (relative to the start
+ * of the page where the registers are mapped) for the counter in question.
+ *
+ * %MMTIMER_GETRES - Returns the resolution of the clock in femto (10^-15)
+ * seconds
+ *
+ * %MMTIMER_GETFREQ - Copies the frequency of the clock in Hz to the address
+ * specified by @arg
+ *
+ * %MMTIMER_GETBITS - Returns the number of bits in the clock's counter
+ *
+ * %MMTIMER_MMAPAVAIL - Returns 1 if registers can be mmap'd into userspace
+ *
+ * %MMTIMER_GETCOUNTER - Gets the current value in the counter and places it
+ * in the address specified by @arg.
+ */
+static long uv_mmtimer_ioctl(struct file *file, unsigned int cmd,
+                                                unsigned long arg)
+{
+        int ret = 0;
+
+        switch (cmd) {
+        case MMTIMER_GETOFFSET: /* offset of the counter */
+                /*
+                 * UV RTC register is on its own page
+                 */
+                if (PAGE_SIZE <= (1 << 16))
+                        ret = ((UV_LOCAL_MMR_BASE | UVH_RTC) & (PAGE_SIZE-1))
+                                / 8;
+                else
+                        ret = -ENOSYS;
+                break;
+
+        case MMTIMER_GETRES: /* resolution of the clock in 10^-15 s */
+                if (copy_to_user((unsigned long __user *)arg,
+                                &uv_mmtimer_femtoperiod, sizeof(unsigned long)))
+                        ret = -EFAULT;
+                break;
+
+        case MMTIMER_GETFREQ: /* frequency in Hz */
+                if (copy_to_user((unsigned long __user *)arg,
+                                &sn_rtc_cycles_per_second,
+                                sizeof(unsigned long)))
+                        ret = -EFAULT;
+                break;
+
+        case MMTIMER_GETBITS: /* number of bits in the clock */
+                ret = hweight64(UVH_RTC_REAL_TIME_CLOCK_MASK);
+                break;
+
+        case MMTIMER_MMAPAVAIL: /* can we mmap the clock into userspace? */
+                ret = (PAGE_SIZE <= (1 << 16)) ? 1 : 0;
+                break;
+
+        case MMTIMER_GETCOUNTER:
+                if (copy_to_user((unsigned long __user *)arg,
+                                (unsigned long *)uv_local_mmr_address(UVH_RTC),
+                                sizeof(unsigned long)))
+                        ret = -EFAULT;
+                break;
+        default:
+                ret = -ENOTTY;
+                break;
+        }
+        return ret;
+}
+
+/**
+ * uv_mmtimer_mmap - maps the clock's registers into userspace
+ * @file: file structure for the device
+ * @vma: VMA to map the registers into
+ *
+ * Calls remap_pfn_range() to map the clock's registers into
+ * the calling process' address space.
+ */
+static int uv_mmtimer_mmap(struct file *file, struct vm_area_struct *vma)
+{
+        unsigned long uv_mmtimer_addr;
+
+        if (vma->vm_end - vma->vm_start != PAGE_SIZE)
+                return -EINVAL;
+
+        if (vma->vm_flags & VM_WRITE)
+                return -EPERM;
+
+        if (PAGE_SIZE > (1 << 16))
+                return -ENOSYS;
+
+        vma->vm_page_prot = pgprot_noncached(vma->vm_page_prot);
+
+        uv_mmtimer_addr = UV_LOCAL_MMR_BASE | UVH_RTC;
+        uv_mmtimer_addr &= ~(PAGE_SIZE - 1);
+        uv_mmtimer_addr &= 0xfffffffffffffffUL;
+
+        if (remap_pfn_range(vma, vma->vm_start, uv_mmtimer_addr >> PAGE_SHIFT,
+                                        PAGE_SIZE, vma->vm_page_prot)) {
+                printk(KERN_ERR "remap_pfn_range failed in uv_mmtimer_mmap\n");
+                return -EAGAIN;
+        }
+
+        return 0;
+}
+
+static struct miscdevice uv_mmtimer_miscdev = {
+        MISC_DYNAMIC_MINOR,
+        UV_MMTIMER_NAME,
+        &uv_mmtimer_fops
+};
+
+
+/**
+ * uv_mmtimer_init - device initialization routine
+ *
+ * Does initial setup for the uv_mmtimer device.
+ */
+static int __init uv_mmtimer_init(void)
+{
+        if (!is_uv_system()) {
+                printk(KERN_ERR "%s: Hardware unsupported\n", UV_MMTIMER_NAME);
+                return -1;
+        }
+
+        /*
+         * Sanity check the cycles/sec variable
+         */
+        if (sn_rtc_cycles_per_second < 100000) {
+                printk(KERN_ERR "%s: unable to determine clock frequency\n",
+                       UV_MMTIMER_NAME);
+                return -1;
+        }
+
+        uv_mmtimer_femtoperiod = ((unsigned long)1E15 +
+                                sn_rtc_cycles_per_second / 2) /
+                                sn_rtc_cycles_per_second;
+
+        if (misc_register(&uv_mmtimer_miscdev)) {
+                printk(KERN_ERR "%s: failed to register device\n",
+                       UV_MMTIMER_NAME);
+                return -1;
+        }
+
+        printk(KERN_INFO "%s: v%s, %ld MHz\n", UV_MMTIMER_DESC,
+                UV_MMTIMER_VERSION,
+                sn_rtc_cycles_per_second/(unsigned long)1E6);
+
+        return 0;
+}
+
+module_init(uv_mmtimer_init);