linux_kernel/arch/powerpc/platforms/powernv/opal-sensor.c

/*
 * PowerNV sensor code
 *
 * Copyright (C) 2013 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.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 */

#include <linux/delay.h>
#include <linux/mutex.h>
#include <asm/opal.h>

static DEFINE_MUTEX(opal_sensor_mutex);

/*
 * This will return sensor information to driver based on the requested sensor
 * handle. A handle is an opaque id for the powernv, read by the driver from the
 * device tree..
 */
int opal_get_sensor_data(u32 sensor_hndl, u32 *sensor_data)
{
	int ret, token;
	struct opal_msg msg;
	__be32 data;

	token = opal_async_get_token_interruptible();
	if (token < 0) {
		pr_err("%s: Couldn't get the token, returning\n", __func__);
		ret = token;
		goto out;
	}

	mutex_lock(&opal_sensor_mutex);
	ret = opal_sensor_read(sensor_hndl, token, &data);
	if (ret != OPAL_ASYNC_COMPLETION)
		goto out_token;

	ret = opal_async_wait_response(token, &msg);
	if (ret) {
		pr_err("%s: Failed to wait for the async response, %d\n",
				__func__, ret);
		goto out_token;
	}

	*sensor_data = be32_to_cpu(data);
	ret = be64_to_cpu(msg.params[1]);

out_token:
	mutex_unlock(&opal_sensor_mutex);
	opal_async_release_token(token);
out:
	return ret;
}
EXPORT_SYMBOL_GPL(opal_get_sensor_data);