linux/arch/powerpc/kernel/rtas-proc.c

// SPDX-License-Identifier: GPL-2.0
/*
 *   Copyright (C) 2000 Tilmann Bitterberg
 *   (tilmann@bitterberg.de)
 *
 *   RTAS (Runtime Abstraction Services) stuff
 *   Intention is to provide a clean user interface
 *   to use the RTAS.
 *
 *   TODO:
 *   Split off a header file and maybe move it to a different
 *   location. Write Documentation on what the /proc/rtas/ entries
 *   actually do.
 */

#include <linux/errno.h>
#include <linux/sched.h>
#include <linux/proc_fs.h>
#include <linux/stat.h>
#include <linux/ctype.h>
#include <linux/time.h>
#include <linux/string.h>
#include <linux/init.h>
#include <linux/seq_file.h>
#include <linux/bitops.h>
#include <linux/rtc.h>
#include <linux/of.h>

#include <linux/uaccess.h>
#include <asm/processor.h>
#include <asm/io.h>
#include <asm/rtas.h>
#include <asm/machdep.h> /* for ppc_md */
#include <asm/time.h>

/* Token for Sensors */
#define KEY_SWITCH		0x0001
#define ENCLOSURE_SWITCH	0x0002
#define THERMAL_SENSOR		0x0003
#define LID_STATUS		0x0004
#define POWER_SOURCE		0x0005
#define BATTERY_VOLTAGE		0x0006
#define BATTERY_REMAINING	0x0007
#define BATTERY_PERCENTAGE	0x0008
#define EPOW_SENSOR		0x0009
#define BATTERY_CYCLESTATE	0x000a
#define BATTERY_CHARGING	0x000b

/* IBM specific sensors */
#define IBM_SURVEILLANCE	0x2328 /* 9000 */
#define IBM_FANRPM		0x2329 /* 9001 */
#define IBM_VOLTAGE		0x232a /* 9002 */
#define IBM_DRCONNECTOR		0x232b /* 9003 */
#define IBM_POWERSUPPLY		0x232c /* 9004 */

/* Status return values */
#define SENSOR_CRITICAL_HIGH	13
#define SENSOR_WARNING_HIGH	12
#define SENSOR_NORMAL		11
#define SENSOR_WARNING_LOW	10
#define SENSOR_CRITICAL_LOW	 9
#define SENSOR_SUCCESS		 0
#define SENSOR_HW_ERROR		-1
#define SENSOR_BUSY		-2
#define SENSOR_NOT_EXIST	-3
#define SENSOR_DR_ENTITY	-9000

/* Location Codes */
#define LOC_SCSI_DEV_ADDR	'A'
#define LOC_SCSI_DEV_LOC	'B'
#define LOC_CPU			'C'
#define LOC_DISKETTE		'D'
#define LOC_ETHERNET		'E'
#define LOC_FAN			'F'
#define LOC_GRAPHICS		'G'
/* reserved / not used		'H' */
#define LOC_IO_ADAPTER		'I'
/* reserved / not used		'J' */
#define LOC_KEYBOARD		'K'
#define LOC_LCD			'L'
#define LOC_MEMORY		'M'
#define LOC_NV_MEMORY		'N'
#define LOC_MOUSE		'O'
#define LOC_PLANAR		'P'
#define LOC_OTHER_IO		'Q'
#define LOC_PARALLEL		'R'
#define LOC_SERIAL		'S'
#define LOC_DEAD_RING		'T'
#define LOC_RACKMOUNTED		'U' /* for _u_nit is rack mounted */
#define LOC_VOLTAGE		'V'
#define LOC_SWITCH_ADAPTER	'W'
#define LOC_OTHER		'X'
#define LOC_FIRMWARE		'Y'
#define LOC_SCSI		'Z'

/* Tokens for indicators */
#define TONE_FREQUENCY		0x0001 /* 0 - 1000 (HZ)*/
#define TONE_VOLUME		0x0002 /* 0 - 100 (%) */
#define SYSTEM_POWER_STATE	0x0003 
#define WARNING_LIGHT		0x0004
#define DISK_ACTIVITY_LIGHT	0x0005
#define HEX_DISPLAY_UNIT	0x0006
#define BATTERY_WARNING_TIME	0x0007
#define CONDITION_CYCLE_REQUEST	0x0008
#define SURVEILLANCE_INDICATOR	0x2328 /* 9000 */
#define DR_ACTION		0x2329 /* 9001 */
#define DR_INDICATOR		0x232a /* 9002 */
/* 9003 - 9004: Vendor specific */
/* 9006 - 9999: Vendor specific */

/* other */
#define MAX_SENSORS		 17  /* I only know of 17 sensors */    
#define MAX_LINELENGTH          256
#define SENSOR_PREFIX		"ibm,sensor-"
#define cel_to_fahr(x)		((x*9/5)+32)

struct individual_sensor {
	unsigned int token;
	unsigned int quant;
};

struct rtas_sensors {
        struct individual_sensor sensor[MAX_SENSORS];
	unsigned int quant;
};

/* Globals */
static struct rtas_sensors sensors;
static struct device_node *rtas_node = NULL;
static unsigned long power_on_time = 0; /* Save the time the user set */
static char progress_led[MAX_LINELENGTH];

static unsigned long rtas_tone_frequency = 1000;
static unsigned long rtas_tone_volume = 0;

/* ****************************************************************** */
/* Declarations */
static int ppc_rtas_sensors_show(struct seq_file *m, void *v);
static int ppc_rtas_clock_show(struct seq_file *m, void *v);
static ssize_t ppc_rtas_clock_write(struct file *file,
		const char __user *buf, size_t count, loff_t *ppos);
static int ppc_rtas_progress_show(struct seq_file *m, void *v);
static ssize_t ppc_rtas_progress_write(struct file *file,
		const char __user *buf, size_t count, loff_t *ppos);
static int ppc_rtas_poweron_show(struct seq_file *m, void *v);
static ssize_t ppc_rtas_poweron_write(struct file *file,
		const char __user *buf, size_t count, loff_t *ppos);

static ssize_t ppc_rtas_tone_freq_write(struct file *file,
		const char __user *buf, size_t count, loff_t *ppos);
static int ppc_rtas_tone_freq_show(struct seq_file *m, void *v);
static ssize_t ppc_rtas_tone_volume_write(struct file *file,
		const char __user *buf, size_t count, loff_t *ppos);
static int ppc_rtas_tone_volume_show(struct seq_file *m, void *v);
static int ppc_rtas_rmo_buf_show(struct seq_file *m, void *v);

static int poweron_open(struct inode *inode, struct file *file)
{
	return single_open(file, ppc_rtas_poweron_show, NULL);
}

static const struct proc_ops ppc_rtas_poweron_proc_ops = {
	.proc_open	= poweron_open,
	.proc_read	= seq_read,
	.proc_lseek	= seq_lseek,
	.proc_write	= ppc_rtas_poweron_write,
	.proc_release	= single_release,
};

static int progress_open(struct inode *inode, struct file *file)
{
	return single_open(file, ppc_rtas_progress_show, NULL);
}

static const struct proc_ops ppc_rtas_progress_proc_ops = {
	.proc_open	= progress_open,
	.proc_read	= seq_read,
	.proc_lseek	= seq_lseek,
	.proc_write	= ppc_rtas_progress_write,
	.proc_release	= single_release,
};

static int clock_open(struct inode *inode, struct file *file)
{
	return single_open(file, ppc_rtas_clock_show, NULL);
}

static const struct proc_ops ppc_rtas_clock_proc_ops = {
	.proc_open	= clock_open,
	.proc_read	= seq_read,
	.proc_lseek	= seq_lseek,
	.proc_write	= ppc_rtas_clock_write,
	.proc_release	= single_release,
};

static int tone_freq_open(struct inode *inode, struct file *file)
{
	return single_open(file, ppc_rtas_tone_freq_show, NULL);
}

static const struct proc_ops ppc_rtas_tone_freq_proc_ops = {
	.proc_open	= tone_freq_open,
	.proc_read	= seq_read,
	.proc_lseek	= seq_lseek,
	.proc_write	= ppc_rtas_tone_freq_write,
	.proc_release	= single_release,
};

static int tone_volume_open(struct inode *inode, struct file *file)
{
	return single_open(file, ppc_rtas_tone_volume_show, NULL);
}

static const struct proc_ops ppc_rtas_tone_volume_proc_ops = {
	.proc_open	= tone_volume_open,
	.proc_read	= seq_read,
	.proc_lseek	= seq_lseek,
	.proc_write	= ppc_rtas_tone_volume_write,
	.proc_release	= single_release,
};

static int ppc_rtas_find_all_sensors(void);
static void ppc_rtas_process_sensor(struct seq_file *m,
	struct individual_sensor *s, int state, int error, const char *loc);
static char *ppc_rtas_process_error(int error);
static void get_location_code(struct seq_file *m,
	struct individual_sensor *s, const char *loc);
static void check_location_string(struct seq_file *m, const char *c);
static void check_location(struct seq_file *m, const char *c);

static int __init proc_rtas_init(void)
{
	if (!machine_is(pseries))
		return -ENODEV;

	rtas_node = of_find_node_by_name(NULL, "rtas");
	if (rtas_node == NULL)
		return -ENODEV;

	proc_create("powerpc/rtas/progress", 0644, NULL,
		    &ppc_rtas_progress_proc_ops);
	proc_create("powerpc/rtas/clock", 0644, NULL,
		    &ppc_rtas_clock_proc_ops);
	proc_create("powerpc/rtas/poweron", 0644, NULL,
		    &ppc_rtas_poweron_proc_ops);
	proc_create_single("powerpc/rtas/sensors", 0444, NULL,
			ppc_rtas_sensors_show);
	proc_create("powerpc/rtas/frequency", 0644, NULL,
		    &ppc_rtas_tone_freq_proc_ops);
	proc_create("powerpc/rtas/volume", 0644, NULL,
		    &ppc_rtas_tone_volume_proc_ops);
	proc_create_single("powerpc/rtas/rmo_buffer", 0400, NULL,
			ppc_rtas_rmo_buf_show);
	return 0;
}

__initcall(proc_rtas_init);

static int parse_number(const char __user *p, size_t count, u64 *val)
{
	char buf[40];

	if (count > 39)
		return -EINVAL;

	if (copy_from_user(buf, p, count))
		return -EFAULT;

	buf[count] = 0;

	return kstrtoull(buf, 10, val);
}

/* ****************************************************************** */
/* POWER-ON-TIME                                                      */
/* ****************************************************************** */
static ssize_t ppc_rtas_poweron_write(struct file *file,
		const char __user *buf, size_t count, loff_t *ppos)
{
	struct rtc_time tm;
	time64_t nowtime;
	int error = parse_number(buf, count, &nowtime);
	if (error)
		return error;

	power_on_time = nowtime; /* save the time */

	rtc_time64_to_tm(nowtime, &tm);

	error = rtas_call(rtas_function_token(RTAS_FN_SET_TIME_FOR_POWER_ON), 7, 1, NULL,
			  tm.tm_year + 1900, tm.tm_mon + 1, tm.tm_mday,
			  tm.tm_hour, tm.tm_min, tm.tm_sec, 0 /* nano */);
	if (error)
		printk(KERN_WARNING "error: setting poweron time returned: %s\n", 
				ppc_rtas_process_error(error));
	return count;
}
/* ****************************************************************** */
static int ppc_rtas_poweron_show(struct seq_file *m, void *v)
{
	if (power_on_time == 0)
		seq_printf(m, "Power on time not set\n");
	else
		seq_printf(m, "%lu\n",power_on_time);
	return 0;
}

/* ****************************************************************** */
/* PROGRESS                                                           */
/* ****************************************************************** */
static ssize_t ppc_rtas_progress_write(struct file *file,
		const char __user *buf, size_t count, loff_t *ppos)
{
	unsigned long hex;

	if (count >= MAX_LINELENGTH)
		count = MAX_LINELENGTH -1;
	if (copy_from_user(progress_led, buf, count)) { /* save the string */
		return -EFAULT;
	}
	progress_led[count] = 0;

	/* Lets see if the user passed hexdigits */
	hex = simple_strtoul(progress_led, NULL, 10);

	rtas_progress ((char *)progress_led, hex);
	return count;

	/* clear the line */
	/* rtas_progress("                   ", 0xffff);*/
}
/* ****************************************************************** */
static int ppc_rtas_progress_show(struct seq_file *m, void *v)
{
	if (progress_led[0])
		seq_printf(m, "%s\n", progress_led);
	return 0;
}

/* ****************************************************************** */
/* CLOCK                                                              */
/* ****************************************************************** */
static ssize_t ppc_rtas_clock_write(struct file *file,
		const char __user *buf, size_t count, loff_t *ppos)
{
	struct rtc_time tm;
	time64_t nowtime;
	int error = parse_number(buf, count, &nowtime);
	if (error)
		return error;

	rtc_time64_to_tm(nowtime, &tm);
	error = rtas_call(rtas_function_token(RTAS_FN_SET_TIME_OF_DAY), 7, 1, NULL,
			  tm.tm_year + 1900, tm.tm_mon + 1, tm.tm_mday,
			  tm.tm_hour, tm.tm_min, tm.tm_sec, 0);
	if (error)
		printk(KERN_WARNING "error: setting the clock returned: %s\n", 
				ppc_rtas_process_error(error));
	return count;
}
/* ****************************************************************** */
static int ppc_rtas_clock_show(struct seq_file *m, void *v)
{
	int ret[8];
	int error = rtas_call(rtas_function_token(RTAS_FN_GET_TIME_OF_DAY), 0, 8, ret);

	if (error) {
		printk(KERN_WARNING "error: reading the clock returned: %s\n", 
				ppc_rtas_process_error(error));
		seq_printf(m, "0");
	} else { 
		unsigned int year, mon, day, hour, min, sec;
		year = ret[0]; mon  = ret[1]; day  = ret[2];
		hour = ret[3]; min  = ret[4]; sec  = ret[5];
		seq_printf(m, "%lld\n",
				mktime64(year, mon, day, hour, min, sec));
	}
	return 0;
}

/* ****************************************************************** */
/* SENSOR STUFF                                                       */
/* ****************************************************************** */
static int ppc_rtas_sensors_show(struct seq_file *m, void *v)
{
	int i,j;
	int state, error;
	int get_sensor_state = rtas_function_token(RTAS_FN_GET_SENSOR_STATE);

	seq_printf(m, "RTAS (RunTime Abstraction Services) Sensor Information\n");
	seq_printf(m, "Sensor\t\tValue\t\tCondition\tLocation\n");
	seq_printf(m, "********************************************************\n");

	if (ppc_rtas_find_all_sensors() != 0) {
		seq_printf(m, "\nNo sensors are available\n");
		return 0;
	}

	for (i=0; i<sensors.quant; i++) {
		struct individual_sensor *p = &sensors.sensor[i];
		char rstr[64];
		const char *loc;
		int llen, offs;

		sprintf (rstr, SENSOR_PREFIX"%04d", p->token);
		loc = of_get_property(rtas_node, rstr, &llen);

		/* A sensor may have multiple instances */
		for (j = 0, offs = 0; j <= p->quant; j++) {
			error =	rtas_call(get_sensor_state, 2, 2, &state, 
				  	  p->token, j);

			ppc_rtas_process_sensor(m, p, state, error, loc);
			seq_putc(m, '\n');
			if (loc) {
				offs += strlen(loc) + 1;
				loc += strlen(loc) + 1;
				if (offs >= llen)
					loc = NULL;
			}
		}
	}
	return 0;
}

/* ****************************************************************** */

static int ppc_rtas_find_all_sensors(void)
{
	const unsigned int *utmp;
	int len, i;

	utmp = of_get_property(rtas_node, "rtas-sensors", &len);
	if (utmp == NULL) {
		printk (KERN_ERR "error: could not get rtas-sensors\n");
		return 1;
	}

	sensors.quant = len / 8;      /* int + int */

	for (i=0; i<sensors.quant; i++) {
		sensors.sensor[i].token = *utmp++;
		sensors.sensor[i].quant = *utmp++;
	}
	return 0;
}

/* ****************************************************************** */
/*
 * Builds a string of what rtas returned
 */
static char *ppc_rtas_process_error(int error)
{
	switch (error) {
		case SENSOR_CRITICAL_HIGH:
			return "(critical high)";
		case SENSOR_WARNING_HIGH:
			return "(warning high)";
		case SENSOR_NORMAL:
			return "(normal)";
		case SENSOR_WARNING_LOW:
			return "(warning low)";
		case SENSOR_CRITICAL_LOW:
			return "(critical low)";
		case SENSOR_SUCCESS:
			return "(read ok)";
		case SENSOR_HW_ERROR:
			return "(hardware error)";
		case SENSOR_BUSY:
			return "(busy)";
		case SENSOR_NOT_EXIST:
			return "(non existent)";
		case SENSOR_DR_ENTITY:
			return "(dr entity removed)";
		default:
			return "(UNKNOWN)";
	}
}

/* ****************************************************************** */
/*
 * Builds a string out of what the sensor said
 */

static void ppc_rtas_process_sensor(struct seq_file *m,
	struct individual_sensor *s, int state, int error, const char *loc)
{
	/* Defined return vales */
	const char * key_switch[]        = { "Off\t", "Normal\t", "Secure\t", 
						"Maintenance" };
	const char * enclosure_switch[]  = { "Closed", "Open" };
	const char * lid_status[]        = { " ", "Open", "Closed" };
	const char * power_source[]      = { "AC\t", "Battery", 
		  				"AC & Battery" };
	const char * battery_remaining[] = { "Very Low", "Low", "Mid", "High" };
	const char * epow_sensor[]       = { 
		"EPOW Reset", "Cooling warning", "Power warning",
		"System shutdown", "System halt", "EPOW main enclosure",
		"EPOW power off" };
	const char * battery_cyclestate[]  = { "None", "In progress", 
						"Requested" };
	const char * battery_charging[]    = { "Charging", "Discharging",
						"No current flow" };
	const char * ibm_drconnector[]     = { "Empty", "Present", "Unusable", 
						"Exchange" };

	int have_strings = 0;
	int num_states = 0;
	int temperature = 0;
	int unknown = 0;

	/* What kind of sensor do we have here? */
	
	switch (s->token) {
		case KEY_SWITCH:
			seq_printf(m, "Key switch:\t");
			num_states = sizeof(key_switch) / sizeof(char *);
			if (state < num_states) {
				seq_printf(m, "%s\t", key_switch[state]);
				have_strings = 1;
			}
			break;
		case ENCLOSURE_SWITCH:
			seq_printf(m, "Enclosure switch:\t");
			num_states = sizeof(enclosure_switch) / sizeof(char *);
			if (state < num_states) {
				seq_printf(m, "%s\t", 
						enclosure_switch[state]);
				have_strings = 1;
			}
			break;
		case THERMAL_SENSOR:
			seq_printf(m, "Temp. (C/F):\t");
			temperature = 1;
			break;
		case LID_STATUS:
			seq_printf(m, "Lid status:\t");
			num_states = sizeof(lid_status) / sizeof(char *);
			if (state < num_states) {
				seq_printf(m, "%s\t", lid_status[state]);
				have_strings = 1;
			}
			break;
		case POWER_SOURCE:
			seq_printf(m, "Power source:\t");
			num_states = sizeof(power_source) / sizeof(char *);
			if (state < num_states) {
				seq_printf(m, "%s\t", 
						power_source[state]);
				have_strings = 1;
			}
			break;
		case BATTERY_VOLTAGE:
			seq_printf(m, "Battery voltage:\t");
			break;
		case BATTERY_REMAINING:
			seq_printf(m, "Battery remaining:\t");
			num_states = sizeof(battery_remaining) / sizeof(char *);
			if (state < num_states)
			{
				seq_printf(m, "%s\t", 
						battery_remaining[state]);
				have_strings = 1;
			}
			break;
		case BATTERY_PERCENTAGE:
			seq_printf(m, "Battery percentage:\t");
			break;
		case EPOW_SENSOR:
			seq_printf(m, "EPOW Sensor:\t");
			num_states = sizeof(epow_sensor) / sizeof(char *);
			if (state < num_states) {
				seq_printf(m, "%s\t", epow_sensor[state]);
				have_strings = 1;
			}
			break;
		case BATTERY_CYCLESTATE:
			seq_printf(m, "Battery cyclestate:\t");
			num_states = sizeof(battery_cyclestate) / 
				     	sizeof(char *);
			if (state < num_states) {
				seq_printf(m, "%s\t", 
						battery_cyclestate[state]);
				have_strings = 1;
			}
			break;
		case BATTERY_CHARGING:
			seq_printf(m, "Battery Charging:\t");
			num_states = sizeof(battery_charging) / sizeof(char *);
			if (state < num_states) {
				seq_printf(m, "%s\t", 
						battery_charging[state]);
				have_strings = 1;
			}
			break;
		case IBM_SURVEILLANCE:
			seq_printf(m, "Surveillance:\t");
			break;
		case IBM_FANRPM:
			seq_printf(m, "Fan (rpm):\t");
			break;
		case IBM_VOLTAGE:
			seq_printf(m, "Voltage (mv):\t");
			break;
		case IBM_DRCONNECTOR:
			seq_printf(m, "DR connector:\t");
			num_states = sizeof(ibm_drconnector) / sizeof(char *);
			if (state < num_states) {
				seq_printf(m, "%s\t", 
						ibm_drconnector[state]);
				have_strings = 1;
			}
			break;
		case IBM_POWERSUPPLY:
			seq_printf(m, "Powersupply:\t");
			break;
		default:
			seq_printf(m,  "Unknown sensor (type %d), ignoring it\n",
					s->token);
			unknown = 1;
			have_strings = 1;
			break;
	}
	if (have_strings == 0) {
		if (temperature) {
			seq_printf(m, "%4d /%4d\t", state, cel_to_fahr(state));
		} else
			seq_printf(m, "%10d\t", state);
	}
	if (unknown == 0) {
		seq_printf(m, "%s\t", ppc_rtas_process_error(error));
		get_location_code(m, s, loc);
	}
}

/* ****************************************************************** */

static void check_location(struct seq_file *m, const char *c)
{
	switch (c[0]) {
		case LOC_PLANAR:
			seq_printf(m, "Planar #%c", c[1]);
			break;
		case LOC_CPU:
			seq_printf(m, "CPU #%c", c[1]);
			break;
		case LOC_FAN:
			seq_printf(m, "Fan #%c", c[1]);
			break;
		case LOC_RACKMOUNTED:
			seq_printf(m, "Rack #%c", c[1]);
			break;
		case LOC_VOLTAGE:
			seq_printf(m, "Voltage #%c", c[1]);
			break;
		case LOC_LCD:
			seq_printf(m, "LCD #%c", c[1]);
			break;
		case '.':
			seq_printf(m, "- %c", c[1]);
			break;
		default:
			seq_printf(m, "Unknown location");
			break;
	}
}


/* ****************************************************************** */
/* 
 * Format: 
 * ${LETTER}${NUMBER}[[-/]${LETTER}${NUMBER} [ ... ] ]
 * the '.' may be an abbreviation
 */
static void check_location_string(struct seq_file *m, const char *c)
{
	while (*c) {
		if (isalpha(*c) || *c == '.')
			check_location(m, c);
		else if (*c == '/' || *c == '-')
			seq_printf(m, " at ");
		c++;
	}
}


/* ****************************************************************** */

static void get_location_code(struct seq_file *m, struct individual_sensor *s,
		const char *loc)
{
	if (!loc || !*loc) {
		seq_printf(m, "---");/* does not have a location */
	} else {
		check_location_string(m, loc);
	}
	seq_putc(m, ' ');
}
/* ****************************************************************** */
/* INDICATORS - Tone Frequency                                        */
/* ****************************************************************** */
static ssize_t ppc_rtas_tone_freq_write(struct file *file,
		const char __user *buf, size_t count, loff_t *ppos)
{
	u64 freq;
	int error = parse_number(buf, count, &freq);
	if (error)
		return error;

	rtas_tone_frequency = freq; /* save it for later */
	error = rtas_call(rtas_function_token(RTAS_FN_SET_INDICATOR), 3, 1, NULL,
			  TONE_FREQUENCY, 0, freq);
	if (error)
		printk(KERN_WARNING "error: setting tone frequency returned: %s\n", 
				ppc_rtas_process_error(error));
	return count;
}
/* ****************************************************************** */
static int ppc_rtas_tone_freq_show(struct seq_file *m, void *v)
{
	seq_printf(m, "%lu\n", rtas_tone_frequency);
	return 0;
}
/* ****************************************************************** */
/* INDICATORS - Tone Volume                                           */
/* ****************************************************************** */
static ssize_t ppc_rtas_tone_volume_write(struct file *file,
		const char __user *buf, size_t count, loff_t *ppos)
{
	u64 volume;
	int error = parse_number(buf, count, &volume);
	if (error)
		return error;

	if (volume > 100)
		volume = 100;
	
        rtas_tone_volume = volume; /* save it for later */
	error = rtas_call(rtas_function_token(RTAS_FN_SET_INDICATOR), 3, 1, NULL,
			  TONE_VOLUME, 0, volume);
	if (error)
		printk(KERN_WARNING "error: setting tone volume returned: %s\n", 
				ppc_rtas_process_error(error));
	return count;
}
/* ****************************************************************** */
static int ppc_rtas_tone_volume_show(struct seq_file *m, void *v)
{
	seq_printf(m, "%lu\n", rtas_tone_volume);
	return 0;
}

/**
 * ppc_rtas_rmo_buf_show() - Describe RTAS-addressable region for user space.
 * @m: seq_file output target.
 * @v: Unused.
 *
 * Base + size description of a range of RTAS-addressable memory set
 * aside for user space to use as work area(s) for certain RTAS
 * functions. User space accesses this region via /dev/mem. Apart from
 * security policies, the kernel does not arbitrate or serialize
 * access to this region, and user space must ensure that concurrent
 * users do not interfere with each other.
 */
static int ppc_rtas_rmo_buf_show(struct seq_file *m, void *v)
{
	seq_printf(m, "%016lx %x\n", rtas_rmo_buf, RTAS_USER_REGION_SIZE);
	return 0;
}