Home | History | Annotate | Line # | Download | only in ti 
      1 /* $NetBSD: ti_rng.c,v 1.7 2022/03/19 11:55:03 riastradh Exp $ */
      2 
      3 /*-
      4  * Copyright (c) 2015 Jared D. McNeill <jmcneill (at) invisible.ca>
      5  * All rights reserved.
      6  *
      7  * Redistribution and use in source and binary forms, with or without
      8  * modification, are permitted provided that the following conditions
      9  * are met:
     10  * 1. Redistributions of source code must retain the above copyright
     11  *    notice, this list of conditions and the following disclaimer.
     12  * 2. The name of the author may not be used to endorse or promote products
     13  *    derived from this software without specific prior written permission.
     14  *
     15  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
     16  * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
     17  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
     18  * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
     19  * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
     20  * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
     21  * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
     22  * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
     23  * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
     24  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
     25  * SUCH DAMAGE.
     26  */
     27 
     28 #include <sys/cdefs.h>
     29 __KERNEL_RCSID(0, "$NetBSD: ti_rng.c,v 1.7 2022/03/19 11:55:03 riastradh Exp $");
     30 
     31 #include <sys/param.h>
     32 #include <sys/systm.h>
     33 #include <sys/device.h>
     34 #include <sys/conf.h>
     35 #include <sys/mutex.h>
     36 #include <sys/bus.h>
     37 #include <sys/rndsource.h>
     38 
     39 #include <dev/fdt/fdtvar.h>
     40 
     41 #include <arm/ti/ti_prcm.h>
     42 #include <arm/ti/ti_rngreg.h>
     43 
     44 static const struct device_compatible_entry compat_data[] = {
     45 	{ .compat = "ti,omap4-rng" },
     46 	DEVICE_COMPAT_EOL
     47 };
     48 
     49 struct ti_rng_softc {
     50 	device_t sc_dev;
     51 	bus_space_tag_t sc_iot;
     52 	bus_space_handle_t sc_ioh;
     53 
     54 	krndsource_t sc_rndsource;
     55 };
     56 
     57 static int	ti_rng_match(device_t, cfdata_t, void *);
     58 static void	ti_rng_attach(device_t, device_t, void *);
     59 static void	ti_rng_callback(size_t, void *);
     60 
     61 CFATTACH_DECL_NEW(ti_rng, sizeof(struct ti_rng_softc),
     62     ti_rng_match, ti_rng_attach, NULL, NULL);
     63 
     64 #define RD4(sc, reg) \
     65 	bus_space_read_4((sc)->sc_iot, (sc)->sc_ioh, (reg))
     66 #define WR4(sc, reg, val) \
     67 	bus_space_write_4((sc)->sc_iot, (sc)->sc_ioh, (reg), (val))
     68 
     69 static int
     70 ti_rng_match(device_t parent, cfdata_t match, void *aux)
     71 {
     72 	struct fdt_attach_args * const faa = aux;
     73 
     74 	return of_compatible_match(faa->faa_phandle, compat_data);
     75 }
     76 
     77 static void
     78 ti_rng_attach(device_t parent, device_t self, void *aux)
     79 {
     80 	struct ti_rng_softc *sc = device_private(self);
     81 	struct fdt_attach_args * const faa = aux;
     82 	const int phandle = faa->faa_phandle;
     83 	bus_addr_t addr;
     84 	bus_size_t size;
     85 
     86 	if (fdtbus_get_reg(phandle, 0, &addr, &size) != 0) {
     87 		aprint_error(": couldn't get registers\n");
     88 		return;
     89 	}
     90 
     91 	if (ti_prcm_enable_hwmod(phandle, 0) != 0) {
     92 		aprint_error(": couldn't enable module\n");
     93 		return;
     94 	}
     95 
     96 	sc->sc_dev = self;
     97 	sc->sc_iot = faa->faa_bst;
     98 	if (bus_space_map(sc->sc_iot, addr, size, 0, &sc->sc_ioh) != 0) {
     99 		aprint_error(": couldn't map registers\n");
    100 		return;
    101 	}
    102 
    103 	if ((RD4(sc, TRNG_CONTROL_REG) & TRNG_CONTROL_ENABLE) == 0) {
    104 		WR4(sc, TRNG_CONFIG_REG,
    105 		    __SHIFTIN(0x21, TRNG_CONFIG_MIN_REFILL) |
    106 		    __SHIFTIN(0x22, TRNG_CONFIG_MAX_REFILL));
    107 		WR4(sc, TRNG_CONTROL_REG,
    108 		    __SHIFTIN(0x21, TRNG_CONTROL_STARTUP_CYCLES) |
    109 		    TRNG_CONTROL_ENABLE);
    110 	}
    111 
    112 	aprint_naive("\n");
    113 	aprint_normal(": RNG\n");
    114 
    115 	rndsource_setcb(&sc->sc_rndsource, ti_rng_callback, sc);
    116 	rnd_attach_source(&sc->sc_rndsource, device_xname(self), RND_TYPE_RNG,
    117 	    RND_FLAG_COLLECT_VALUE|RND_FLAG_HASCB);
    118 }
    119 
    120 static void
    121 ti_rng_callback(size_t bytes_wanted, void *priv)
    122 {
    123 	struct ti_rng_softc * const sc = priv;
    124 	uint32_t buf[2];
    125 	u_int retry;
    126 
    127 	while (bytes_wanted) {
    128 		for (retry = 10; retry > 0; retry--) {
    129 			if (RD4(sc, TRNG_STATUS_REG) & TRNG_STATUS_READY)
    130 				break;
    131 			delay(10);
    132 		}
    133 		if (retry == 0)
    134 			break;
    135 		buf[0] = RD4(sc, TRNG_OUTPUT_L_REG);
    136 		buf[1] = RD4(sc, TRNG_OUTPUT_H_REG);
    137 		WR4(sc, TRNG_INTACK_REG, TRNG_INTACK_READY);
    138 		rnd_add_data_sync(&sc->sc_rndsource, buf, sizeof(buf),
    139 		    sizeof(buf) * NBBY);
    140 		bytes_wanted -= MIN(bytes_wanted, sizeof(buf));
    141 	}
    142 	explicit_memset(buf, 0, sizeof(buf));
    143 }
    144