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      1 /*	$NetBSD: bcm2835_mbox_subr.c,v 1.5 2017/12/10 21:38:26 skrll Exp $	*/
      2 
      3 /*-
      4  * Copyright (c) 2012 The NetBSD Foundation, Inc.
      5  * All rights reserved.
      6  *
      7  * This code is derived from software contributed to The NetBSD Foundation
      8  * by Nick Hudson
      9  *
     10  * Redistribution and use in source and binary forms, with or without
     11  * modification, are permitted provided that the following conditions
     12  * are met:
     13  * 1. Redistributions of source code must retain the above copyright
     14  *    notice, this list of conditions and the following disclaimer.
     15  * 2. Redistributions in binary form must reproduce the above copyright
     16  *    notice, this list of conditions and the following disclaimer in the
     17  *    documentation and/or other materials provided with the distribution.
     18  *
     19  * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
     20  * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
     21  * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
     22  * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
     23  * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
     24  * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
     25  * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
     26  * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
     27  * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
     28  * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
     29  * POSSIBILITY OF SUCH DAMAGE.
     30  */
     31 
     32 #include <sys/cdefs.h>
     33 __KERNEL_RCSID(0, "$NetBSD: bcm2835_mbox_subr.c,v 1.5 2017/12/10 21:38:26 skrll Exp $");
     34 
     35 #include <sys/param.h>
     36 #include <sys/systm.h>
     37 #include <sys/device.h>
     38 #include <sys/kernel.h>
     39 #include <sys/timetc.h>
     40 #include <sys/bus.h>
     41 
     42 #include <arm/broadcom/bcm2835_mbox.h>
     43 #include <arm/broadcom/bcm2835_mboxreg.h>
     44 #include <arm/broadcom/bcm2835reg.h>
     45 
     46 void
     47 bcm2835_mbox_read(bus_space_tag_t iot, bus_space_handle_t ioh, uint8_t chan,
     48     uint32_t *data)
     49 {
     50 	uint32_t mbox;
     51 
     52 	KASSERT((chan & 0xf) == chan);
     53 
     54 	for (;;) {
     55 		uint8_t rchan;
     56 		uint32_t rdata;
     57 
     58 		bus_space_barrier(iot, ioh, 0, BCM2835_MBOX_SIZE,
     59 		    BUS_SPACE_BARRIER_READ);
     60 
     61 		if ((bus_space_read_4(iot, ioh,
     62 		    BCM2835_MBOX0_STATUS) & BCM2835_MBOX_STATUS_EMPTY) != 0)
     63 			continue;
     64 
     65 		mbox = bus_space_read_4(iot, ioh, BCM2835_MBOX0_READ);
     66 
     67 		rchan = BCM2835_MBOX_CHAN(mbox);
     68 		rdata = BCM2835_MBOX_DATA(mbox);
     69 
     70 		if (rchan == chan) {
     71 			*data = rdata;
     72 			return;
     73 		}
     74 	}
     75 }
     76 
     77 void
     78 bcm2835_mbox_write(bus_space_tag_t iot, bus_space_handle_t ioh, uint8_t chan,
     79     uint32_t data)
     80 {
     81 	uint32_t rdata;
     82 
     83 	KASSERT((chan & 0xf) == chan);
     84 	KASSERT((data & 0xf) == 0);
     85 	for (;;) {
     86 
     87 		bus_space_barrier(iot, ioh, 0, BCM2835_MBOX_SIZE,
     88 		    BUS_SPACE_BARRIER_READ);
     89 
     90 		if ((rdata = bus_space_read_4(iot, ioh,
     91 		    BCM2835_MBOX0_STATUS) & BCM2835_MBOX_STATUS_FULL) == 0)
     92 			break;
     93 	}
     94 
     95 	bus_space_write_4(iot, ioh, BCM2835_MBOX1_WRITE,
     96 	    BCM2835_MBOX_MSG(chan, data));
     97 
     98 	bus_space_barrier(iot, ioh, 0, BCM2835_MBOX_SIZE,
     99 	    BUS_SPACE_BARRIER_WRITE);
    100 }
    101