/*
 * SN2 Platform specific SMP Support
 *
 * 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) 2000-2006 Silicon Graphics, Inc. All rights reserved.
 */

#include <linux/init.h>
#include <linux/kernel.h>
#include <linux/spinlock.h>
#include <linux/threads.h>
#include <linux/sched.h>
#include <linux/smp.h>
#include <linux/interrupt.h>
#include <linux/irq.h>
#include <linux/mmzone.h>
#include <linux/module.h>
#include <linux/bitops.h>
#include <linux/nodemask.h>
#include <linux/proc_fs.h>
#include <linux/seq_file.h>

#include <asm/processor.h>
#include <asm/irq.h>
#include <asm/sal.h>
#include <asm/system.h>
#include <asm/delay.h>
#include <asm/io.h>
#include <asm/smp.h>
#include <asm/tlb.h>
#include <asm/numa.h>
#include <asm/hw_irq.h>
#include <asm/current.h>
#include <asm/sn/sn_cpuid.h>
#include <asm/sn/sn_sal.h>
#include <asm/sn/addrs.h>
#include <asm/sn/shub_mmr.h>
#include <asm/sn/nodepda.h>
#include <asm/sn/rw_mmr.h>
#include <asm/sn/sn_feature_sets.h>

DEFINE_PER_CPU(struct ptc_stats, ptcstats);
DECLARE_PER_CPU(struct ptc_stats, ptcstats);

static  __cacheline_aligned DEFINE_SPINLOCK(sn2_global_ptc_lock);

/* 0 = old algorithm (no IPI flushes), 1 = ipi deadlock flush, 2 = ipi instead of SHUB ptc, >2 = always ipi */
static int sn2_flush_opt = 0;

extern unsigned long
sn2_ptc_deadlock_recovery_core(volatile unsigned long *, unsigned long,
                               volatile unsigned long *, unsigned long,
                               volatile unsigned long *, unsigned long);
void
sn2_ptc_deadlock_recovery(short *, short, short, int,
                          volatile unsigned long *, unsigned long,
                          volatile unsigned long *, unsigned long);

/*
 * Note: some is the following is captured here to make degugging easier
 * (the macros make more sense if you see the debug patch - not posted)
 */
#define sn2_ptctest     0
#define local_node_uses_ptc_ga(sh1)     ((sh1) ? 1 : 0)
#define max_active_pio(sh1)             ((sh1) ? 32 : 7)
#define reset_max_active_on_deadlock()  1
#define PTC_LOCK(sh1)                   ((sh1) ? &sn2_global_ptc_lock : &sn_nodepda->ptc_lock)

struct ptc_stats {
        unsigned long ptc_l;
        unsigned long change_rid;
        unsigned long shub_ptc_flushes;
        unsigned long nodes_flushed;
        unsigned long deadlocks;
        unsigned long deadlocks2;
        unsigned long lock_itc_clocks;
        unsigned long shub_itc_clocks;
        unsigned long shub_itc_clocks_max;
        unsigned long shub_ptc_flushes_not_my_mm;
        unsigned long shub_ipi_flushes;
        unsigned long shub_ipi_flushes_itc_clocks;
};

#define sn2_ptctest     0

static inline unsigned long wait_piowc(void)
{
        volatile unsigned long *piows;
        unsigned long zeroval, ws;

        piows = pda->pio_write_status_addr;
        zeroval = pda->pio_write_status_val;
        do {
                cpu_relax();
        } while (((ws = *piows) & SH_PIO_WRITE_STATUS_PENDING_WRITE_COUNT_MASK) != zeroval);
        return (ws & SH_PIO_WRITE_STATUS_WRITE_DEADLOCK_MASK) != 0;
}

/**
 * sn_migrate - SN-specific task migration actions
 * @task: Task being migrated to new CPU
 *
 * SN2 PIO writes from separate CPUs are not guaranteed to arrive in order.
 * Context switching user threads which have memory-mapped MMIO may cause
 * PIOs to issue from separate CPUs, thus the PIO writes must be drained
 * from the previous CPU's Shub before execution resumes on the new CPU.
 */
void sn_migrate(struct task_struct *task)
{
        pda_t *last_pda = pdacpu(task_thread_info(task)->last_cpu);
        volatile unsigned long *adr = last_pda->pio_write_status_addr;
        unsigned long val = last_pda->pio_write_status_val;

        /* Drain PIO writes from old CPU's Shub */
        while (unlikely((*adr & SH_PIO_WRITE_STATUS_PENDING_WRITE_COUNT_MASK)
                        != val))
                cpu_relax();
}

void sn_tlb_migrate_finish(struct mm_struct *mm)
{
        /* flush_tlb_mm is inefficient if more than 1 users of mm */
        if (mm == current->mm && mm && atomic_read(&mm->mm_users) == 1)
                flush_tlb_mm(mm);
}

static void
sn2_ipi_flush_all_tlb(struct mm_struct *mm)
{
        unsigned long itc;

        itc = ia64_get_itc();
        smp_flush_tlb_cpumask(*mm_cpumask(mm));
        itc = ia64_get_itc() - itc;
        __get_cpu_var(ptcstats).shub_ipi_flushes_itc_clocks += itc;
        __get_cpu_var(ptcstats).shub_ipi_flushes++;
}

/**
 * sn2_global_tlb_purge - globally purge translation cache of virtual address range
 * @mm: mm_struct containing virtual address range
 * @start: start of virtual address range
 * @end: end of virtual address range
 * @nbits: specifies number of bytes to purge per instruction (num = 1<<(nbits & 0xfc))
 *
 * Purges the translation caches of all processors of the given virtual address
 * range.
 *
 * Note:
 *      - cpu_vm_mask is a bit mask that indicates which cpus have loaded the context.
 *      - cpu_vm_mask is converted into a nodemask of the nodes containing the
 *        cpus in cpu_vm_mask.
 *      - if only one bit is set in cpu_vm_mask & it is the current cpu & the
 *        process is purging its own virtual address range, then only the
 *        local TLB needs to be flushed. This flushing can be done using
 *        ptc.l. This is the common case & avoids the global spinlock.
 *      - if multiple cpus have loaded the context, then flushing has to be
 *        done with ptc.g/MMRs under protection of the global ptc_lock.
 */

void
sn2_global_tlb_purge(struct mm_struct *mm, unsigned long start,
                     unsigned long end, unsigned long nbits)
{
        int i, ibegin, shub1, cnode, mynasid, cpu, lcpu = 0, nasid;
        int mymm = (mm == current->active_mm && mm == current->mm);
        int use_cpu_ptcga;
        volatile unsigned long *ptc0, *ptc1;
        unsigned long itc, itc2, flags, data0 = 0, data1 = 0, rr_value, old_rr = 0;
        short nasids[MAX_NUMNODES], nix;
        nodemask_t nodes_flushed;
        int active, max_active, deadlock, flush_opt = sn2_flush_opt;

        if (flush_opt > 2) {
                sn2_ipi_flush_all_tlb(mm);
                return;
        }

        nodes_clear(nodes_flushed);
        i = 0;

        for_each_cpu(cpu, mm_cpumask(mm)) {
                cnode = cpu_to_node(cpu);
                node_set(cnode, nodes_flushed);
                lcpu = cpu;
                i++;
        }

        if (i == 0)
                return;

        preempt_disable();

        if (likely(i == 1 && lcpu == smp_processor_id() && mymm)) {
                do {
                        ia64_ptcl(start, nbits << 2);
                        start += (1UL << nbits);
                } while (start < end);
                ia64_srlz_i();
                __get_cpu_var(ptcstats).ptc_l++;
                preempt_enable();
                return;
        }

        if (atomic_read(&mm->mm_users) == 1 && mymm) {
                flush_tlb_mm(mm);
                __get_cpu_var(ptcstats).change_rid++;
                preempt_enable();
                return;
        }

        if (flush_opt == 2) {
                sn2_ipi_flush_all_tlb(mm);
                preempt_enable();
                return;
        }

        itc = ia64_get_itc();
        nix = 0;
        for_each_node_mask(cnode, nodes_flushed)
                nasids[nix++] = cnodeid_to_nasid(cnode);

        rr_value = (mm->context << 3) | REGION_NUMBER(start);

        shub1 = is_shub1();
        if (shub1) {
                data0 = (1UL << SH1_PTC_0_A_SHFT) |
                        (nbits << SH1_PTC_0_PS_SHFT) |
                        (rr_value << SH1_PTC_0_RID_SHFT) |
                        (1UL << SH1_PTC_0_START_SHFT);
                ptc0 = (long *)GLOBAL_MMR_PHYS_ADDR(0, SH1_PTC_0);
                ptc1 = (long *)GLOBAL_MMR_PHYS_ADDR(0, SH1_PTC_1);
        } else {
                data0 = (1UL << SH2_PTC_A_SHFT) |
                        (nbits << SH2_PTC_PS_SHFT) |
                        (1UL << SH2_PTC_START_SHFT);
                ptc0 = (long *)GLOBAL_MMR_PHYS_ADDR(0, SH2_PTC + 
                        (rr_value << SH2_PTC_RID_SHFT));
                ptc1 = NULL;
        }
        

        mynasid = get_nasid();
        use_cpu_ptcga = local_node_uses_ptc_ga(shub1);
        max_active = max_active_pio(shub1);

        itc = ia64_get_itc();
        spin_lock_irqsave(PTC_LOCK(shub1), flags);
        itc2 = ia64_get_itc();

        __get_cpu_var(ptcstats).lock_itc_clocks += itc2 - itc;
        __get_cpu_var(ptcstats).shub_ptc_flushes++;
        __get_cpu_var(ptcstats).nodes_flushed += nix;
        if (!mymm)
                 __get_cpu_var(ptcstats).shub_ptc_flushes_not_my_mm++;

        if (use_cpu_ptcga && !mymm) {
                old_rr = ia64_get_rr(start);
                ia64_set_rr(start, (old_rr & 0xff) | (rr_value << 8));
                ia64_srlz_d();
        }

        wait_piowc();
        do {
                if (shub1)
                        data1 = start | (1UL << SH1_PTC_1_START_SHFT);
                else
                        data0 = (data0 & ~SH2_PTC_ADDR_MASK) | (start & SH2_PTC_ADDR_MASK);
                deadlock = 0;
                active = 0;
                for (ibegin = 0, i = 0; i < nix; i++) {
                        nasid = nasids[i];
                        if (use_cpu_ptcga && unlikely(nasid == mynasid)) {
                                ia64_ptcga(start, nbits << 2);
                                ia64_srlz_i();
                        } else {
                                ptc0 = CHANGE_NASID(nasid, ptc0);
                                if (ptc1)
                                        ptc1 = CHANGE_NASID(nasid, ptc1);
                                pio_atomic_phys_write_mmrs(ptc0, data0, ptc1, data1);
                                active++;
                        }
                        if (active >= max_active || i == (nix - 1)) {
                                if ((deadlock = wait_piowc())) {
                                        if (flush_opt == 1)
                                                goto done;
                                        sn2_ptc_deadlock_recovery(nasids, ibegin, i, mynasid, ptc0, data0, ptc1, data1);
                                        if (reset_max_active_on_deadlock())
                                                max_active = 1;
                                }
                                active = 0;
                                ibegin = i + 1;
                        }
                }
                start += (1UL << nbits);
        } while (start < end);

done:
        itc2 = ia64_get_itc() - itc2;
        __get_cpu_var(ptcstats).shub_itc_clocks += itc2;
        if (itc2 > __get_cpu_var(ptcstats).shub_itc_clocks_max)
                __get_cpu_var(ptcstats).shub_itc_clocks_max = itc2;

        if (old_rr) {
                ia64_set_rr(start, old_rr);
                ia64_srlz_d();
        }

        spin_unlock_irqrestore(PTC_LOCK(shub1), flags);

        if (flush_opt == 1 && deadlock) {
                __get_cpu_var(ptcstats).deadlocks++;
                sn2_ipi_flush_all_tlb(mm);
        }

        preempt_enable();
}

/*
 * sn2_ptc_deadlock_recovery
 *
 * Recover from PTC deadlocks conditions. Recovery requires stepping thru each 
 * TLB flush transaction.  The recovery sequence is somewhat tricky & is
 * coded in assembly language.
 */

void
sn2_ptc_deadlock_recovery(short *nasids, short ib, short ie, int mynasid,
                          volatile unsigned long *ptc0, unsigned long data0,
                          volatile unsigned long *ptc1, unsigned long data1)
{
        short nasid, i;
        unsigned long *piows, zeroval, n;

        __get_cpu_var(ptcstats).deadlocks++;

        piows = (unsigned long *) pda->pio_write_status_addr;
        zeroval = pda->pio_write_status_val;


        for (i=ib; i <= ie; i++) {
                nasid = nasids[i];
                if (local_node_uses_ptc_ga(is_shub1()) && nasid == mynasid)
                        continue;
                ptc0 = CHANGE_NASID(nasid, ptc0);
                if (ptc1)
                        ptc1 = CHANGE_NASID(nasid, ptc1);

                n = sn2_ptc_deadlock_recovery_core(ptc0, data0, ptc1, data1, piows, zeroval);
                __get_cpu_var(ptcstats).deadlocks2 += n;
        }

}

/**
 * sn_send_IPI_phys - send an IPI to a Nasid and slice
 * @nasid: nasid to receive the interrupt (may be outside partition)
 * @physid: physical cpuid to receive the interrupt.
 * @vector: command to send
 * @delivery_mode: delivery mechanism
 *
 * Sends an IPI (interprocessor interrupt) to the processor specified by
 * @physid
 *
 * @delivery_mode can be one of the following
 *
 * %IA64_IPI_DM_INT - pend an interrupt
 * %IA64_IPI_DM_PMI - pend a PMI
 * %IA64_IPI_DM_NMI - pend an NMI
 * %IA64_IPI_DM_INIT - pend an INIT interrupt
 */
void sn_send_IPI_phys(int nasid, long physid, int vector, int delivery_mode)
{
        long val;
        unsigned long flags = 0;
        volatile long *p;

        p = (long *)GLOBAL_MMR_PHYS_ADDR(nasid, SH_IPI_INT);
        val = (1UL << SH_IPI_INT_SEND_SHFT) |
            (physid << SH_IPI_INT_PID_SHFT) |
            ((long)delivery_mode << SH_IPI_INT_TYPE_SHFT) |
            ((long)vector << SH_IPI_INT_IDX_SHFT) |
            (0x000feeUL << SH_IPI_INT_BASE_SHFT);

        mb();
        if (enable_shub_wars_1_1()) {
                spin_lock_irqsave(&sn2_global_ptc_lock, flags);
        }
        pio_phys_write_mmr(p, val);
        if (enable_shub_wars_1_1()) {
                wait_piowc();
                spin_unlock_irqrestore(&sn2_global_ptc_lock, flags);
        }

}

EXPORT_SYMBOL(sn_send_IPI_phys);

/**
 * sn2_send_IPI - send an IPI to a processor
 * @cpuid: target of the IPI
 * @vector: command to send
 * @delivery_mode: delivery mechanism
 * @redirect: redirect the IPI?
 *
 * Sends an IPI (InterProcessor Interrupt) to the processor specified by
 * @cpuid.  @vector specifies the command to send, while @delivery_mode can 
 * be one of the following
 *
 * %IA64_IPI_DM_INT - pend an interrupt
 * %IA64_IPI_DM_PMI - pend a PMI
 * %IA64_IPI_DM_NMI - pend an NMI
 * %IA64_IPI_DM_INIT - pend an INIT interrupt
 */
void sn2_send_IPI(int cpuid, int vector, int delivery_mode, int redirect)
{
        long physid;
        int nasid;

        physid = cpu_physical_id(cpuid);
        nasid = cpuid_to_nasid(cpuid);

        /* the following is used only when starting cpus at boot time */
        if (unlikely(nasid == -1))
                ia64_sn_get_sapic_info(physid, &nasid, NULL, NULL);

        sn_send_IPI_phys(nasid, physid, vector, delivery_mode);
}

#ifdef CONFIG_HOTPLUG_CPU
/**
 * sn_cpu_disable_allowed - Determine if a CPU can be disabled.
 * @cpu - CPU that is requested to be disabled.
 *
 * CPU disable is only allowed on SHub2 systems running with a PROM
 * that supports CPU disable. It is not permitted to disable the boot processor.
 */
bool sn_cpu_disable_allowed(int cpu)
{
        if (is_shub2() && sn_prom_feature_available(PRF_CPU_DISABLE_SUPPORT)) {
                if (cpu != 0)
                        return true;
                else
                        printk(KERN_WARNING
                              "Disabling the boot processor is not allowed.\n");

        } else
                printk(KERN_WARNING
                       "CPU disable is not supported on this system.\n");

        return false;
}
#endif /* CONFIG_HOTPLUG_CPU */

#ifdef CONFIG_PROC_FS

#define PTC_BASENAME    "sgi_sn/ptc_statistics"

static void *sn2_ptc_seq_start(struct seq_file *file, loff_t * offset)
{
        if (*offset < nr_cpu_ids)
                return offset;
        return NULL;
}

static void *sn2_ptc_seq_next(struct seq_file *file, void *data, loff_t * offset)
{
        (*offset)++;
        if (*offset < nr_cpu_ids)
                return offset;
        return NULL;
}

static void sn2_ptc_seq_stop(struct seq_file *file, void *data)
{
}

static int sn2_ptc_seq_show(struct seq_file *file, void *data)
{
        struct ptc_stats *stat;
        int cpu;

        cpu = *(loff_t *) data;

        if (!cpu) {
                seq_printf(file,
                           "# cpu ptc_l newrid ptc_flushes nodes_flushed deadlocks lock_nsec shub_nsec shub_nsec_max not_my_mm deadlock2 ipi_fluches ipi_nsec\n");
                seq_printf(file, "# ptctest %d, flushopt %d\n", sn2_ptctest, sn2_flush_opt);
        }

        if (cpu < nr_cpu_ids && cpu_online(cpu)) {
                stat = &per_cpu(ptcstats, cpu);
                seq_printf(file, "cpu %d %ld %ld %ld %ld %ld %ld %ld %ld %ld %ld %ld %ld\n", cpu, stat->ptc_l,
                                stat->change_rid, stat->shub_ptc_flushes, stat->nodes_flushed,
                                stat->deadlocks,
                                1000 * stat->lock_itc_clocks / per_cpu(cpu_info, cpu).cyc_per_usec,
                                1000 * stat->shub_itc_clocks / per_cpu(cpu_info, cpu).cyc_per_usec,
                                1000 * stat->shub_itc_clocks_max / per_cpu(cpu_info, cpu).cyc_per_usec,
                                stat->shub_ptc_flushes_not_my_mm,
                                stat->deadlocks2,
                                stat->shub_ipi_flushes,
                                1000 * stat->shub_ipi_flushes_itc_clocks / per_cpu(cpu_info, cpu).cyc_per_usec);
        }
        return 0;
}

static ssize_t sn2_ptc_proc_write(struct file *file, const char __user *user, size_t count, loff_t *data)
{
        int cpu;
        char optstr[64];

        if (count == 0 || count > sizeof(optstr))
                return -EINVAL;
        if (copy_from_user(optstr, user, count))
                return -EFAULT;
        optstr[count - 1] = '\0';
        sn2_flush_opt = simple_strtoul(optstr, NULL, 0);

        for_each_online_cpu(cpu)
                memset(&per_cpu(ptcstats, cpu), 0, sizeof(struct ptc_stats));

        return count;
}

static const struct seq_operations sn2_ptc_seq_ops = {
        .start = sn2_ptc_seq_start,
        .next = sn2_ptc_seq_next,
        .stop = sn2_ptc_seq_stop,
        .show = sn2_ptc_seq_show
};

static int sn2_ptc_proc_open(struct inode *inode, struct file *file)
{
        return seq_open(file, &sn2_ptc_seq_ops);
}

static const struct file_operations proc_sn2_ptc_operations = {
        .open = sn2_ptc_proc_open,
        .read = seq_read,
        .write = sn2_ptc_proc_write,
        .llseek = seq_lseek,
        .release = seq_release,
};

static struct proc_dir_entry *proc_sn2_ptc;

static int __init sn2_ptc_init(void)
{
        if (!ia64_platform_is("sn2"))
                return 0;

        proc_sn2_ptc = proc_create(PTC_BASENAME, 0444,
                                   NULL, &proc_sn2_ptc_operations);
        if (!proc_sn2_ptc) {
                printk(KERN_ERR "unable to create %s proc entry", PTC_BASENAME);
                return -EINVAL;
        }
        spin_lock_init(&sn2_global_ptc_lock);
        return 0;
}

static void __exit sn2_ptc_exit(void)
{
        remove_proc_entry(PTC_BASENAME, NULL);
}

module_init(sn2_ptc_init);
module_exit(sn2_ptc_exit);
#endif /* CONFIG_PROC_FS */