1 /* $NetBSD: meson_rng.c,v 1.5 2022/03/19 11:36:43 riastradh Exp $ */ 2 3 /*- 4 * Copyright (c) 2015-2019 Jared D. McNeill <jmcneill@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. Redistributions in binary form must reproduce the above copyright 13 * notice, this list of conditions and the following disclaimer in the 14 * documentation and/or other materials provided with the distribution. 15 * 16 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR 17 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES 18 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. 19 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, 20 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, 21 * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; 22 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED 23 * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, 24 * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 25 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 26 * SUCH DAMAGE. 27 */ 28 29 #include <sys/cdefs.h> 30 __KERNEL_RCSID(0, "$NetBSD: meson_rng.c,v 1.5 2022/03/19 11:36:43 riastradh Exp $"); 31 32 #include <sys/param.h> 33 #include <sys/bus.h> 34 #include <sys/device.h> 35 #include <sys/systm.h> 36 #include <sys/kernel.h> 37 #include <sys/mutex.h> 38 #include <sys/rndsource.h> 39 40 #include <dev/fdt/fdtvar.h> 41 42 static int meson_rng_match(device_t, cfdata_t, void *); 43 static void meson_rng_attach(device_t, device_t, void *); 44 45 static void meson_rng_get(size_t, void *); 46 47 struct meson_rng_softc { 48 device_t sc_dev; 49 bus_space_tag_t sc_bst; 50 bus_space_handle_t sc_bsh; 51 52 krndsource_t sc_rndsource; 53 }; 54 55 static const struct device_compatible_entry compat_data[] = { 56 { .compat = "amlogic,meson-rng" }, 57 DEVICE_COMPAT_EOL 58 }; 59 60 CFATTACH_DECL_NEW(meson_rng, sizeof(struct meson_rng_softc), 61 meson_rng_match, meson_rng_attach, NULL, NULL); 62 63 static int 64 meson_rng_match(device_t parent, cfdata_t cf, void *aux) 65 { 66 struct fdt_attach_args * const faa = aux; 67 68 return of_compatible_match(faa->faa_phandle, compat_data); 69 } 70 71 static void 72 meson_rng_attach(device_t parent, device_t self, void *aux) 73 { 74 struct meson_rng_softc * const sc = device_private(self); 75 struct fdt_attach_args * const faa = aux; 76 const int phandle = faa->faa_phandle; 77 struct clk *clk; 78 bus_addr_t addr; 79 bus_size_t size; 80 81 if (fdtbus_get_reg(phandle, 0, &addr, &size) != 0) { 82 aprint_error(": couldn't get registers\n"); 83 return; 84 } 85 86 sc->sc_dev = self; 87 sc->sc_bst = faa->faa_bst; 88 if (bus_space_map(sc->sc_bst, addr, size, 0, &sc->sc_bsh) != 0) { 89 aprint_error(": couldn't map registers\n"); 90 return; 91 } 92 93 /* Core clock is optional */ 94 clk = fdtbus_clock_get(phandle, "core"); 95 if (clk != NULL && clk_enable(clk) != 0) { 96 aprint_error(": couldn't enable core clock\n"); 97 return; 98 } 99 100 aprint_naive("\n"); 101 aprint_normal(": Hardware RNG\n"); 102 103 rndsource_setcb(&sc->sc_rndsource, meson_rng_get, sc); 104 rnd_attach_source(&sc->sc_rndsource, device_xname(self), RND_TYPE_RNG, 105 RND_FLAG_COLLECT_VALUE|RND_FLAG_HASCB); 106 } 107 108 static void 109 meson_rng_get(size_t bytes_wanted, void *priv) 110 { 111 struct meson_rng_softc * const sc = priv; 112 uint32_t data; 113 114 while (bytes_wanted) { 115 data = bus_space_read_4(sc->sc_bst, sc->sc_bsh, 0); 116 rnd_add_data_sync(&sc->sc_rndsource, &data, sizeof(data), 117 sizeof(data) * NBBY); 118 bytes_wanted -= MIN(bytes_wanted, sizeof(data)); 119 } 120 explicit_memset(&data, 0, sizeof(data)); 121 } 122