powerpc: Use one common impl. of RTAS timebase sync and use raw spinlock

[linux-2.6/mini2440.git] / arch / powerpc / kernel / rtas.c

/*
 *
 * Procedures for interfacing to the RTAS on CHRP machines.
 *
 * Peter Bergner, IBM   March 2001.
 * Copyright (C) 2001 IBM.
 *
 *      This program is free software; you can redistribute it and/or
 *      modify it under the terms of the GNU General Public License
 *      as published by the Free Software Foundation; either version
 *      2 of the License, or (at your option) any later version.
 */

#include <stdarg.h>
#include <linux/kernel.h>
#include <linux/types.h>
#include <linux/spinlock.h>
#include <linux/module.h>
#include <linux/init.h>
#include <linux/capability.h>
#include <linux/delay.h>
#include <linux/smp.h>
#include <linux/completion.h>
#include <linux/cpumask.h>
#include <linux/lmb.h>

#include <asm/prom.h>
#include <asm/rtas.h>
#include <asm/hvcall.h>
#include <asm/machdep.h>
#include <asm/firmware.h>
#include <asm/page.h>
#include <asm/param.h>
#include <asm/system.h>
#include <asm/delay.h>
#include <asm/uaccess.h>
#include <asm/udbg.h>
#include <asm/syscalls.h>
#include <asm/smp.h>
#include <asm/atomic.h>
#include <asm/time.h>

struct rtas_t rtas = {
        .lock = __RAW_SPIN_LOCK_UNLOCKED
};
EXPORT_SYMBOL(rtas);

struct rtas_suspend_me_data {
        atomic_t working; /* number of cpus accessing this struct */
        atomic_t done;
        int token; /* ibm,suspend-me */
        int error;
        struct completion *complete; /* wait on this until working == 0 */
};

DEFINE_SPINLOCK(rtas_data_buf_lock);
EXPORT_SYMBOL(rtas_data_buf_lock);

char rtas_data_buf[RTAS_DATA_BUF_SIZE] __cacheline_aligned;
EXPORT_SYMBOL(rtas_data_buf);

unsigned long rtas_rmo_buf;

/*
 * If non-NULL, this gets called when the kernel terminates.
 * This is done like this so rtas_flash can be a module.
 */
void (*rtas_flash_term_hook)(int);
EXPORT_SYMBOL(rtas_flash_term_hook);

/* RTAS use home made raw locking instead of spin_lock_irqsave
 * because those can be called from within really nasty contexts
 * such as having the timebase stopped which would lockup with
 * normal locks and spinlock debugging enabled
 */
static unsigned long lock_rtas(void)
{
        unsigned long flags;

        local_irq_save(flags);
        preempt_disable();
        __raw_spin_lock_flags(&rtas.lock, flags);
        return flags;
}

static void unlock_rtas(unsigned long flags)
{
        __raw_spin_unlock(&rtas.lock);
        local_irq_restore(flags);
        preempt_enable();
}

/*
 * call_rtas_display_status and call_rtas_display_status_delay
 * are designed only for very early low-level debugging, which
 * is why the token is hard-coded to 10.
 */
static void call_rtas_display_status(char c)
{
        struct rtas_args *args = &rtas.args;
        unsigned long s;

        if (!rtas.base)
                return;
        s = lock_rtas();

        args->token = 10;
        args->nargs = 1;
        args->nret  = 1;
        args->rets  = (rtas_arg_t *)&(args->args[1]);
        args->args[0] = (unsigned char)c;

        enter_rtas(__pa(args));

        unlock_rtas(s);
}

static void call_rtas_display_status_delay(char c)
{
        static int pending_newline = 0;  /* did last write end with unprinted newline? */
        static int width = 16;

        if (c == '\n') {        
                while (width-- > 0)
                        call_rtas_display_status(' ');
                width = 16;
                mdelay(500);
                pending_newline = 1;
        } else {
                if (pending_newline) {
                        call_rtas_display_status('\r');
                        call_rtas_display_status('\n');
                } 
                pending_newline = 0;
                if (width--) {
                        call_rtas_display_status(c);
                        udelay(10000);
                }
        }
}

void __init udbg_init_rtas_panel(void)
{
        udbg_putc = call_rtas_display_status_delay;
}

#ifdef CONFIG_UDBG_RTAS_CONSOLE

/* If you think you're dying before early_init_dt_scan_rtas() does its
 * work, you can hard code the token values for your firmware here and
 * hardcode rtas.base/entry etc.
 */
static unsigned int rtas_putchar_token = RTAS_UNKNOWN_SERVICE;
static unsigned int rtas_getchar_token = RTAS_UNKNOWN_SERVICE;

static void udbg_rtascon_putc(char c)
{
        int tries;

        if (!rtas.base)
                return;

        /* Add CRs before LFs */
        if (c == '\n')
                udbg_rtascon_putc('\r');

        /* if there is more than one character to be displayed, wait a bit */
        for (tries = 0; tries < 16; tries++) {
                if (rtas_call(rtas_putchar_token, 1, 1, NULL, c) == 0)
                        break;
                udelay(1000);
        }
}

static int udbg_rtascon_getc_poll(void)
{
        int c;

        if (!rtas.base)
                return -1;

        if (rtas_call(rtas_getchar_token, 0, 2, &c))
                return -1;

        return c;
}

static int udbg_rtascon_getc(void)
{
        int c;

        while ((c = udbg_rtascon_getc_poll()) == -1)
                ;

        return c;
}


void __init udbg_init_rtas_console(void)
{
        udbg_putc = udbg_rtascon_putc;
        udbg_getc = udbg_rtascon_getc;
        udbg_getc_poll = udbg_rtascon_getc_poll;
}
#endif /* CONFIG_UDBG_RTAS_CONSOLE */

void rtas_progress(char *s, unsigned short hex)
{
        struct device_node *root;
        int width;
        const int *p;
        char *os;
        static int display_character, set_indicator;
        static int display_width, display_lines, form_feed;
        static const int *row_width;
        static DEFINE_SPINLOCK(progress_lock);
        static int current_line;
        static int pending_newline = 0;  /* did last write end with unprinted newline? */

        if (!rtas.base)
                return;

        if (display_width == 0) {
                display_width = 0x10;
                if ((root = of_find_node_by_path("/rtas"))) {
                        if ((p = of_get_property(root,
                                        "ibm,display-line-length", NULL)))
                                display_width = *p;
                        if ((p = of_get_property(root,
                                        "ibm,form-feed", NULL)))
                                form_feed = *p;
                        if ((p = of_get_property(root,
                                        "ibm,display-number-of-lines", NULL)))
                                display_lines = *p;
                        row_width = of_get_property(root,
                                        "ibm,display-truncation-length", NULL);
                        of_node_put(root);
                }
                display_character = rtas_token("display-character");
                set_indicator = rtas_token("set-indicator");
        }

        if (display_character == RTAS_UNKNOWN_SERVICE) {
                /* use hex display if available */
                if (set_indicator != RTAS_UNKNOWN_SERVICE)
                        rtas_call(set_indicator, 3, 1, NULL, 6, 0, hex);
                return;
        }

        spin_lock(&progress_lock);

        /*
         * Last write ended with newline, but we didn't print it since
         * it would just clear the bottom line of output. Print it now
         * instead.
         *
         * If no newline is pending and form feed is supported, clear the
         * display with a form feed; otherwise, print a CR to start output
         * at the beginning of the line.
         */
        if (pending_newline) {
                rtas_call(display_character, 1, 1, NULL, '\r');
                rtas_call(display_character, 1, 1, NULL, '\n');
                pending_newline = 0;
        } else {
                current_line = 0;
                if (form_feed)
                        rtas_call(display_character, 1, 1, NULL,
                                  (char)form_feed);
                else
                        rtas_call(display_character, 1, 1, NULL, '\r');
        }
 
        if (row_width)
                width = row_width[current_line];
        else
                width = display_width;
        os = s;
        while (*os) {
                if (*os == '\n' || *os == '\r') {
                        /* If newline is the last character, save it
                         * until next call to avoid bumping up the
                         * display output.
                         */
                        if (*os == '\n' && !os[1]) {
                                pending_newline = 1;
                                current_line++;
                                if (current_line > display_lines-1)
                                        current_line = display_lines-1;
                                spin_unlock(&progress_lock);
                                return;
                        }
 
                        /* RTAS wants CR-LF, not just LF */
 
                        if (*os == '\n') {
                                rtas_call(display_character, 1, 1, NULL, '\r');
                                rtas_call(display_character, 1, 1, NULL, '\n');
                        } else {
                                /* CR might be used to re-draw a line, so we'll
                                 * leave it alone and not add LF.
                                 */
                                rtas_call(display_character, 1, 1, NULL, *os);
                        }
 
                        if (row_width)
                                width = row_width[current_line];
                        else
                                width = display_width;
                } else {
                        width--;
                        rtas_call(display_character, 1, 1, NULL, *os);
                }
 
                os++;
 
                /* if we overwrite the screen length */
                if (width <= 0)
                        while ((*os != 0) && (*os != '\n') && (*os != '\r'))
                                os++;
        }
 
        spin_unlock(&progress_lock);
}
EXPORT_SYMBOL(rtas_progress);           /* needed by rtas_flash module */

int rtas_token(const char *service)
{
        const int *tokp;
        if (rtas.dev == NULL)
                return RTAS_UNKNOWN_SERVICE;
        tokp = of_get_property(rtas.dev, service, NULL);
        return tokp ? *tokp : RTAS_UNKNOWN_SERVICE;
}
EXPORT_SYMBOL(rtas_token);

int rtas_service_present(const char *service)
{
        return rtas_token(service) != RTAS_UNKNOWN_SERVICE;
}
EXPORT_SYMBOL(rtas_service_present);

#ifdef CONFIG_RTAS_ERROR_LOGGING
/*
 * Return the firmware-specified size of the error log buffer
 *  for all rtas calls that require an error buffer argument.
 *  This includes 'check-exception' and 'rtas-last-error'.
 */
int rtas_get_error_log_max(void)
{
        static int rtas_error_log_max;
        if (rtas_error_log_max)
                return rtas_error_log_max;

        rtas_error_log_max = rtas_token ("rtas-error-log-max");
        if ((rtas_error_log_max == RTAS_UNKNOWN_SERVICE) ||
            (rtas_error_log_max > RTAS_ERROR_LOG_MAX)) {
                printk (KERN_WARNING "RTAS: bad log buffer size %d\n",
                        rtas_error_log_max);
                rtas_error_log_max = RTAS_ERROR_LOG_MAX;
        }
        return rtas_error_log_max;
}
EXPORT_SYMBOL(rtas_get_error_log_max);


static char rtas_err_buf[RTAS_ERROR_LOG_MAX];
static int rtas_last_error_token;

/** Return a copy of the detailed error text associated with the
 *  most recent failed call to rtas.  Because the error text
 *  might go stale if there are any other intervening rtas calls,
 *  this routine must be called atomically with whatever produced
 *  the error (i.e. with rtas.lock still held from the previous call).
 */
static char *__fetch_rtas_last_error(char *altbuf)
{
        struct rtas_args err_args, save_args;
        u32 bufsz;
        char *buf = NULL;

        if (rtas_last_error_token == -1)
                return NULL;

        bufsz = rtas_get_error_log_max();

        err_args.token = rtas_last_error_token;
        err_args.nargs = 2;
        err_args.nret = 1;
        err_args.args[0] = (rtas_arg_t)__pa(rtas_err_buf);
        err_args.args[1] = bufsz;
        err_args.args[2] = 0;

        save_args = rtas.args;
        rtas.args = err_args;

        enter_rtas(__pa(&rtas.args));

        err_args = rtas.args;
        rtas.args = save_args;

        /* Log the error in the unlikely case that there was one. */
        if (unlikely(err_args.args[2] == 0)) {
                if (altbuf) {
                        buf = altbuf;
                } else {
                        buf = rtas_err_buf;
                        if (mem_init_done)
                                buf = kmalloc(RTAS_ERROR_LOG_MAX, GFP_ATOMIC);
                }
                if (buf)
                        memcpy(buf, rtas_err_buf, RTAS_ERROR_LOG_MAX);
        }

        return buf;
}

#define get_errorlog_buffer()   kmalloc(RTAS_ERROR_LOG_MAX, GFP_KERNEL)

#else /* CONFIG_RTAS_ERROR_LOGGING */
#define __fetch_rtas_last_error(x)      NULL
#define get_errorlog_buffer()           NULL
#endif

int rtas_call(int token, int nargs, int nret, int *outputs, ...)
{
        va_list list;
        int i;
        unsigned long s;
        struct rtas_args *rtas_args;
        char *buff_copy = NULL;
        int ret;

        if (!rtas.entry || token == RTAS_UNKNOWN_SERVICE)
                return -1;

        s = lock_rtas();
        rtas_args = &rtas.args;

        rtas_args->token = token;
        rtas_args->nargs = nargs;
        rtas_args->nret  = nret;
        rtas_args->rets  = (rtas_arg_t *)&(rtas_args->args[nargs]);
        va_start(list, outputs);
        for (i = 0; i < nargs; ++i)
                rtas_args->args[i] = va_arg(list, rtas_arg_t);
        va_end(list);

        for (i = 0; i < nret; ++i)
                rtas_args->rets[i] = 0;

        enter_rtas(__pa(rtas_args));

        /* A -1 return code indicates that the last command couldn't
           be completed due to a hardware error. */
        if (rtas_args->rets[0] == -1)
                buff_copy = __fetch_rtas_last_error(NULL);

        if (nret > 1 && outputs != NULL)
                for (i = 0; i < nret-1; ++i)
                        outputs[i] = rtas_args->rets[i+1];
        ret = (nret > 0)? rtas_args->rets[0]: 0;

        unlock_rtas(s);

        if (buff_copy) {
                log_error(buff_copy, ERR_TYPE_RTAS_LOG, 0);
                if (mem_init_done)
                        kfree(buff_copy);
        }
        return ret;
}
EXPORT_SYMBOL(rtas_call);

/* For RTAS_BUSY (-2), delay for 1 millisecond.  For an extended busy status
 * code of 990n, perform the hinted delay of 10^n (last digit) milliseconds.
 */
unsigned int rtas_busy_delay_time(int status)
{
        int order;
        unsigned int ms = 0;

        if (status == RTAS_BUSY) {
                ms = 1;
        } else if (status >= 9900 && status <= 9905) {
                order = status - 9900;
                for (ms = 1; order > 0; order--)
                        ms *= 10;
        }

        return ms;
}
EXPORT_SYMBOL(rtas_busy_delay_time);

/* For an RTAS busy status code, perform the hinted delay. */
unsigned int rtas_busy_delay(int status)
{
        unsigned int ms;

        might_sleep();
        ms = rtas_busy_delay_time(status);
        if (ms)
                msleep(ms);

        return ms;
}
EXPORT_SYMBOL(rtas_busy_delay);

static int rtas_error_rc(int rtas_rc)
{
        int rc;

        switch (rtas_rc) {
                case -1:                /* Hardware Error */
                        rc = -EIO;
                        break;
                case -3:                /* Bad indicator/domain/etc */
                        rc = -EINVAL;
                        break;
                case -9000:             /* Isolation error */
                        rc = -EFAULT;
                        break;
                case -9001:             /* Outstanding TCE/PTE */
                        rc = -EEXIST;
                        break;
                case -9002:             /* No usable slot */
                        rc = -ENODEV;
                        break;
                default:
                        printk(KERN_ERR "%s: unexpected RTAS error %d\n",
                                        __func__, rtas_rc);
                        rc = -ERANGE;
                        break;
        }
        return rc;
}

int rtas_get_power_level(int powerdomain, int *level)
{
        int token = rtas_token("get-power-level");
        int rc;

        if (token == RTAS_UNKNOWN_SERVICE)
                return -ENOENT;

        while ((rc = rtas_call(token, 1, 2, level, powerdomain)) == RTAS_BUSY)
                udelay(1);

        if (rc < 0)
                return rtas_error_rc(rc);
        return rc;
}
EXPORT_SYMBOL(rtas_get_power_level);

int rtas_set_power_level(int powerdomain, int level, int *setlevel)
{
        int token = rtas_token("set-power-level");
        int rc;

        if (token == RTAS_UNKNOWN_SERVICE)
                return -ENOENT;

        do {
                rc = rtas_call(token, 2, 2, setlevel, powerdomain, level);
        } while (rtas_busy_delay(rc));

        if (rc < 0)
                return rtas_error_rc(rc);
        return rc;
}
EXPORT_SYMBOL(rtas_set_power_level);

int rtas_get_sensor(int sensor, int index, int *state)
{
        int token = rtas_token("get-sensor-state");
        int rc;

        if (token == RTAS_UNKNOWN_SERVICE)
                return -ENOENT;

        do {
                rc = rtas_call(token, 2, 2, state, sensor, index);
        } while (rtas_busy_delay(rc));

        if (rc < 0)
                return rtas_error_rc(rc);
        return rc;
}
EXPORT_SYMBOL(rtas_get_sensor);

bool rtas_indicator_present(int token, int *maxindex)
{
        int proplen, count, i;
        const struct indicator_elem {
                u32 token;
                u32 maxindex;
        } *indicators;

        indicators = of_get_property(rtas.dev, "rtas-indicators", &proplen);
        if (!indicators)
                return false;

        count = proplen / sizeof(struct indicator_elem);

        for (i = 0; i < count; i++) {
                if (indicators[i].token != token)
                        continue;
                if (maxindex)
                        *maxindex = indicators[i].maxindex;
                return true;
        }

        return false;
}
EXPORT_SYMBOL(rtas_indicator_present);

int rtas_set_indicator(int indicator, int index, int new_value)
{
        int token = rtas_token("set-indicator");
        int rc;

        if (token == RTAS_UNKNOWN_SERVICE)
                return -ENOENT;

        do {
                rc = rtas_call(token, 3, 1, NULL, indicator, index, new_value);
        } while (rtas_busy_delay(rc));

        if (rc < 0)
                return rtas_error_rc(rc);
        return rc;
}
EXPORT_SYMBOL(rtas_set_indicator);

/*
 * Ignoring RTAS extended delay
 */
int rtas_set_indicator_fast(int indicator, int index, int new_value)
{
        int rc;
        int token = rtas_token("set-indicator");

        if (token == RTAS_UNKNOWN_SERVICE)
                return -ENOENT;

        rc = rtas_call(token, 3, 1, NULL, indicator, index, new_value);

        WARN_ON(rc == -2 || (rc >= 9900 && rc <= 9905));

        if (rc < 0)
                return rtas_error_rc(rc);

        return rc;
}

void rtas_restart(char *cmd)
{
        if (rtas_flash_term_hook)
                rtas_flash_term_hook(SYS_RESTART);
        printk("RTAS system-reboot returned %d\n",
               rtas_call(rtas_token("system-reboot"), 0, 1, NULL));
        for (;;);
}

void rtas_power_off(void)
{
        if (rtas_flash_term_hook)
                rtas_flash_term_hook(SYS_POWER_OFF);
        /* allow power on only with power button press */
        printk("RTAS power-off returned %d\n",
               rtas_call(rtas_token("power-off"), 2, 1, NULL, -1, -1));
        for (;;);
}

void rtas_halt(void)
{
        if (rtas_flash_term_hook)
                rtas_flash_term_hook(SYS_HALT);
        /* allow power on only with power button press */
        printk("RTAS power-off returned %d\n",
               rtas_call(rtas_token("power-off"), 2, 1, NULL, -1, -1));
        for (;;);
}

/* Must be in the RMO region, so we place it here */
static char rtas_os_term_buf[2048];

void rtas_os_term(char *str)
{
        int status;

        if (panic_timeout)
                return;

        if (RTAS_UNKNOWN_SERVICE == rtas_token("ibm,os-term"))
                return;

        snprintf(rtas_os_term_buf, 2048, "OS panic: %s", str);

        do {
                status = rtas_call(rtas_token("ibm,os-term"), 1, 1, NULL,
                                   __pa(rtas_os_term_buf));
        } while (rtas_busy_delay(status));

        if (status != 0)
                printk(KERN_EMERG "ibm,os-term call failed %d\n",
                               status);
}

static int ibm_suspend_me_token = RTAS_UNKNOWN_SERVICE;
#ifdef CONFIG_PPC_PSERIES
static void rtas_percpu_suspend_me(void *info)
{
        long rc = H_SUCCESS;
        unsigned long msr_save;
        int cpu;
        struct rtas_suspend_me_data *data =
                (struct rtas_suspend_me_data *)info;

        atomic_inc(&data->working);

        /* really need to ensure MSR.EE is off for H_JOIN */
        msr_save = mfmsr();
        mtmsr(msr_save & ~(MSR_EE));

        while (rc == H_SUCCESS && !atomic_read(&data->done))
                rc = plpar_hcall_norets(H_JOIN);

        mtmsr(msr_save);

        if (rc == H_SUCCESS) {
                /* This cpu was prodded and the suspend is complete. */
                goto out;
        } else if (rc == H_CONTINUE) {
                /* All other cpus are in H_JOIN, this cpu does
                 * the suspend.
                 */
                printk(KERN_DEBUG "calling ibm,suspend-me on cpu %i\n",
                       smp_processor_id());
                data->error = rtas_call(data->token, 0, 1, NULL);

                if (data->error)
                        printk(KERN_DEBUG "ibm,suspend-me returned %d\n",
                               data->error);
        } else {
                printk(KERN_ERR "H_JOIN on cpu %i failed with rc = %ld\n",
                       smp_processor_id(), rc);
                data->error = rc;
        }

        atomic_set(&data->done, 1);

        /* This cpu did the suspend or got an error; in either case,
         * we need to prod all other other cpus out of join state.
         * Extra prods are harmless.
         */
        for_each_online_cpu(cpu)
                plpar_hcall_norets(H_PROD, get_hard_smp_processor_id(cpu));
out:
        if (atomic_dec_return(&data->working) == 0)
                complete(data->complete);
}

static int rtas_ibm_suspend_me(struct rtas_args *args)
{
        long state;
        long rc;
        unsigned long retbuf[PLPAR_HCALL_BUFSIZE];
        struct rtas_suspend_me_data data;
        DECLARE_COMPLETION_ONSTACK(done);

        if (!rtas_service_present("ibm,suspend-me"))
                return -ENOSYS;

        /* Make sure the state is valid */
        rc = plpar_hcall(H_VASI_STATE, retbuf,
                         ((u64)args->args[0] << 32) | args->args[1]);

        state = retbuf[0];

        if (rc) {
                printk(KERN_ERR "rtas_ibm_suspend_me: vasi_state returned %ld\n",rc);
                return rc;
        } else if (state == H_VASI_ENABLED) {
                args->args[args->nargs] = RTAS_NOT_SUSPENDABLE;
                return 0;
        } else if (state != H_VASI_SUSPENDING) {
                printk(KERN_ERR "rtas_ibm_suspend_me: vasi_state returned state %ld\n",
                       state);
                args->args[args->nargs] = -1;
                return 0;
        }

        atomic_set(&data.working, 0);
        atomic_set(&data.done, 0);
        data.token = rtas_token("ibm,suspend-me");
        data.error = 0;
        data.complete = &done;

        /* Call function on all CPUs.  One of us will make the
         * rtas call
         */
        if (on_each_cpu(rtas_percpu_suspend_me, &data, 0))
                data.error = -EINVAL;

        wait_for_completion(&done);

        if (data.error != 0)
                printk(KERN_ERR "Error doing global join\n");

        return data.error;
}
#else /* CONFIG_PPC_PSERIES */
static int rtas_ibm_suspend_me(struct rtas_args *args)
{
        return -ENOSYS;
}
#endif

asmlinkage int ppc_rtas(struct rtas_args __user *uargs)
{
        struct rtas_args args;
        unsigned long flags;
        char *buff_copy, *errbuf = NULL;
        int nargs;
        int rc;

        if (!capable(CAP_SYS_ADMIN))
                return -EPERM;

        if (copy_from_user(&args, uargs, 3 * sizeof(u32)) != 0)
                return -EFAULT;

        nargs = args.nargs;
        if (nargs > ARRAY_SIZE(args.args)
            || args.nret > ARRAY_SIZE(args.args)
            || nargs + args.nret > ARRAY_SIZE(args.args))
                return -EINVAL;

        /* Copy in args. */
        if (copy_from_user(args.args, uargs->args,
                           nargs * sizeof(rtas_arg_t)) != 0)
                return -EFAULT;

        if (args.token == RTAS_UNKNOWN_SERVICE)
                return -EINVAL;

        args.rets = &args.args[nargs];
        memset(args.rets, 0, args.nret * sizeof(rtas_arg_t));

        /* Need to handle ibm,suspend_me call specially */
        if (args.token == ibm_suspend_me_token) {
                rc = rtas_ibm_suspend_me(&args);
                if (rc)
                        return rc;
                goto copy_return;
        }

        buff_copy = get_errorlog_buffer();

        flags = lock_rtas();

        rtas.args = args;
        enter_rtas(__pa(&rtas.args));
        args = rtas.args;

        /* A -1 return code indicates that the last command couldn't
           be completed due to a hardware error. */
        if (args.rets[0] == -1)
                errbuf = __fetch_rtas_last_error(buff_copy);

        unlock_rtas(flags);

        if (buff_copy) {
                if (errbuf)
                        log_error(errbuf, ERR_TYPE_RTAS_LOG, 0);
                kfree(buff_copy);
        }

 copy_return:
        /* Copy out args. */
        if (copy_to_user(uargs->args + nargs,
                         args.args + nargs,
                         args.nret * sizeof(rtas_arg_t)) != 0)
                return -EFAULT;

        return 0;
}

/*
 * Call early during boot, before mem init or bootmem, to retrieve the RTAS
 * informations from the device-tree and allocate the RMO buffer for userland
 * accesses.
 */
void __init rtas_initialize(void)
{
        unsigned long rtas_region = RTAS_INSTANTIATE_MAX;

        /* Get RTAS dev node and fill up our "rtas" structure with infos
         * about it.
         */
        rtas.dev = of_find_node_by_name(NULL, "rtas");
        if (rtas.dev) {
                const u32 *basep, *entryp, *sizep;

                basep = of_get_property(rtas.dev, "linux,rtas-base", NULL);
                sizep = of_get_property(rtas.dev, "rtas-size", NULL);
                if (basep != NULL && sizep != NULL) {
                        rtas.base = *basep;
                        rtas.size = *sizep;
                        entryp = of_get_property(rtas.dev,
                                        "linux,rtas-entry", NULL);
                        if (entryp == NULL) /* Ugh */
                                rtas.entry = rtas.base;
                        else
                                rtas.entry = *entryp;
                } else
                        rtas.dev = NULL;
        }
        if (!rtas.dev)
                return;

        /* If RTAS was found, allocate the RMO buffer for it and look for
         * the stop-self token if any
         */
#ifdef CONFIG_PPC64
        if (machine_is(pseries) && firmware_has_feature(FW_FEATURE_LPAR)) {
                rtas_region = min(lmb.rmo_size, RTAS_INSTANTIATE_MAX);
                ibm_suspend_me_token = rtas_token("ibm,suspend-me");
        }
#endif
        rtas_rmo_buf = lmb_alloc_base(RTAS_RMOBUF_MAX, PAGE_SIZE, rtas_region);

#ifdef CONFIG_RTAS_ERROR_LOGGING
        rtas_last_error_token = rtas_token("rtas-last-error");
#endif
}

int __init early_init_dt_scan_rtas(unsigned long node,
                const char *uname, int depth, void *data)
{
        u32 *basep, *entryp, *sizep;

        if (depth != 1 || strcmp(uname, "rtas") != 0)
                return 0;

        basep  = of_get_flat_dt_prop(node, "linux,rtas-base", NULL);
        entryp = of_get_flat_dt_prop(node, "linux,rtas-entry", NULL);
        sizep  = of_get_flat_dt_prop(node, "rtas-size", NULL);

        if (basep && entryp && sizep) {
                rtas.base = *basep;
                rtas.entry = *entryp;
                rtas.size = *sizep;
        }

#ifdef CONFIG_UDBG_RTAS_CONSOLE
        basep = of_get_flat_dt_prop(node, "put-term-char", NULL);
        if (basep)
                rtas_putchar_token = *basep;

        basep = of_get_flat_dt_prop(node, "get-term-char", NULL);
        if (basep)
                rtas_getchar_token = *basep;

        if (rtas_putchar_token != RTAS_UNKNOWN_SERVICE &&
            rtas_getchar_token != RTAS_UNKNOWN_SERVICE)
                udbg_init_rtas_console();

#endif

        /* break now */
        return 1;
}

static raw_spinlock_t timebase_lock;
static u64 timebase = 0;

void __cpuinit rtas_give_timebase(void)
{
        unsigned long flags;

        local_irq_save(flags);
        hard_irq_disable();
        __raw_spin_lock(&timebase_lock);
        rtas_call(rtas_token("freeze-time-base"), 0, 1, NULL);
        timebase = get_tb();
        __raw_spin_unlock(&timebase_lock);

        while (timebase)
                barrier();
        rtas_call(rtas_token("thaw-time-base"), 0, 1, NULL);
        local_irq_restore(flags);
}

void __cpuinit rtas_take_timebase(void)
{
        while (!timebase)
                barrier();
        __raw_spin_lock(&timebase_lock);
        set_tb(timebase >> 32, timebase & 0xffffffff);
        timebase = 0;
        __raw_spin_unlock(&timebase_lock);
}