pwm_backlight.c revision 1.1
1 /* $NetBSD: pwm_backlight.c,v 1.1 2018/05/06 10:33:21 jmcneill Exp $ */ 2 3 /*- 4 * Copyright (c) 2018 Jared 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. 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: pwm_backlight.c,v 1.1 2018/05/06 10:33:21 jmcneill 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/sysctl.h> 37 #include <sys/kmem.h> 38 #include <sys/gpio.h> 39 40 #include <dev/pwm/pwmvar.h> 41 42 #include <dev/fdt/fdtvar.h> 43 44 struct pwm_backlight_softc { 45 device_t sc_dev; 46 pwm_tag_t sc_pwm; 47 struct fdtbus_gpio_pin *sc_pin; 48 49 u_int *sc_levels; 50 u_int sc_nlevels; 51 52 char *sc_levelstr; 53 }; 54 55 static int pwm_backlight_match(device_t, cfdata_t, void *); 56 static void pwm_backlight_attach(device_t, device_t, void *); 57 58 static void pwm_backlight_sysctl_init(struct pwm_backlight_softc *); 59 static void pwm_backlight_pmf_init(struct pwm_backlight_softc *); 60 static void pwm_backlight_set(struct pwm_backlight_softc *, u_int); 61 static u_int pwm_backlight_get(struct pwm_backlight_softc *); 62 63 static const char *compatible[] = { 64 "pwm-backlight", 65 NULL 66 }; 67 68 CFATTACH_DECL_NEW(pwmbacklight, sizeof(struct pwm_backlight_softc), 69 pwm_backlight_match, pwm_backlight_attach, NULL, NULL); 70 71 static int 72 pwm_backlight_match(device_t parent, cfdata_t cf, void *aux) 73 { 74 struct fdt_attach_args * const faa = aux; 75 76 return of_match_compatible(faa->faa_phandle, compatible); 77 } 78 79 static void 80 pwm_backlight_attach(device_t parent, device_t self, void *aux) 81 { 82 struct pwm_backlight_softc * const sc = device_private(self); 83 struct fdt_attach_args * const faa = aux; 84 const int phandle = faa->faa_phandle; 85 const u_int *levels; 86 u_int default_level; 87 u_int n; 88 int len; 89 90 sc->sc_dev = self; 91 sc->sc_pwm = fdtbus_pwm_acquire(phandle, "pwms"); 92 if (sc->sc_pwm == NULL) { 93 aprint_error(": couldn't acquire pwm\n"); 94 return; 95 } 96 if (of_hasprop(phandle, "enable-gpios")) { 97 sc->sc_pin = fdtbus_gpio_acquire(phandle, "enable-gpios", 98 GPIO_PIN_OUTPUT); 99 if (!sc->sc_pin) { 100 aprint_error(": couldn't acquire enable gpio\n"); 101 return; 102 } 103 } 104 105 levels = fdtbus_get_prop(phandle, "brightness-levels", &len); 106 if (len < 4) { 107 aprint_error(": couldn't get 'brightness-levels' property\n"); 108 return; 109 } 110 sc->sc_levels = kmem_alloc(len, KM_SLEEP); 111 sc->sc_nlevels = len / 4; 112 for (n = 0; n < sc->sc_nlevels; n++) 113 sc->sc_levels[n] = be32toh(levels[n]); 114 115 aprint_naive("\n"); 116 aprint_normal(": PWM Backlight"); 117 aprint_verbose(" <"); 118 for (n = 0; n < sc->sc_nlevels; n++) { 119 aprint_verbose("%s%u", n ? " " : "", sc->sc_levels[n]); 120 } 121 aprint_verbose(">"); 122 aprint_normal("\n"); 123 124 if (of_getprop_uint32(phandle, "default-brightness-level", &default_level) == 0) { 125 /* set the default level now */ 126 pwm_backlight_set(sc, default_level); 127 } 128 129 pwm_backlight_sysctl_init(sc); 130 pwm_backlight_pmf_init(sc); 131 } 132 133 static void 134 pwm_backlight_set(struct pwm_backlight_softc *sc, u_int index) 135 { 136 struct pwm_config conf; 137 138 if (index >= sc->sc_nlevels) 139 return; 140 141 aprint_debug_dev(sc->sc_dev, "set duty cycle to %u%%\n", sc->sc_levels[index]); 142 143 pwm_disable(sc->sc_pwm); 144 pwm_get_config(sc->sc_pwm, &conf); 145 conf.duty_cycle = (conf.period * sc->sc_levels[index]) / sc->sc_levels[sc->sc_nlevels - 1]; 146 pwm_set_config(sc->sc_pwm, &conf); 147 pwm_enable(sc->sc_pwm); 148 } 149 150 static u_int 151 pwm_backlight_get(struct pwm_backlight_softc *sc) 152 { 153 struct pwm_config conf; 154 u_int raw_val, n; 155 156 pwm_get_config(sc->sc_pwm, &conf); 157 158 raw_val = (conf.duty_cycle * sc->sc_levels[sc->sc_nlevels - 1]) / conf.period; 159 160 /* Return the closest setting to the raw value */ 161 for (n = 0; n < sc->sc_nlevels; n++) { 162 if (raw_val <= sc->sc_levels[n]) 163 break; 164 } 165 return n; 166 } 167 168 static int 169 pwm_backlight_sysctl_helper(SYSCTLFN_ARGS) 170 { 171 struct pwm_backlight_softc * const sc = rnode->sysctl_data; 172 struct sysctlnode node; 173 int error; 174 u_int level, n; 175 176 node = *rnode; 177 node.sysctl_data = &level; 178 179 n = pwm_backlight_get(sc); 180 level = sc->sc_levels[n]; 181 182 error = sysctl_lookup(SYSCTLFN_CALL(&node)); 183 if (error || newp == NULL) 184 return error; 185 186 for (n = 0; n < sc->sc_nlevels; n++) { 187 if (sc->sc_levels[n] == level) { 188 pwm_backlight_set(sc, n); 189 return 0; 190 } 191 } 192 193 return EINVAL; 194 } 195 196 static void 197 pwm_backlight_sysctl_init(struct pwm_backlight_softc *sc) 198 { 199 const struct sysctlnode *node, *pwmnode; 200 struct sysctllog *log = NULL; 201 int error; 202 u_int n; 203 204 sc->sc_levelstr = kmem_zalloc(strlen("XXXXX ") * sc->sc_nlevels, KM_SLEEP); 205 for (n = 0; n < sc->sc_nlevels; n++) { 206 char buf[7]; 207 snprintf(buf, sizeof(buf), n ? " %u" : "%u", sc->sc_levels[n]); 208 strcat(sc->sc_levelstr, buf); 209 } 210 211 error = sysctl_createv(&log, 0, NULL, &node, 212 CTLFLAG_PERMANENT, CTLTYPE_NODE, "hw", NULL, 213 NULL, 0, NULL, 0, CTL_HW, CTL_EOL); 214 if (error) 215 goto failed; 216 217 error = sysctl_createv(&log, 0, &node, &pwmnode, 218 0, CTLTYPE_NODE, device_xname(sc->sc_dev), NULL, 219 NULL, 0, NULL, 0, CTL_CREATE, CTL_EOL); 220 if (error) 221 goto failed; 222 223 error = sysctl_createv(&log, 0, &pwmnode, NULL, 224 0, CTLTYPE_STRING, "levels", NULL, 225 NULL, 0, sc->sc_levelstr, NULL, 226 CTL_CREATE, CTL_EOL); 227 if (error) 228 goto failed; 229 230 error = sysctl_createv(&log, 0, &pwmnode, NULL, 231 CTLFLAG_READWRITE, CTLTYPE_INT, "level", NULL, 232 pwm_backlight_sysctl_helper, 0, (void *)sc, 0, 233 CTL_CREATE, CTL_EOL); 234 if (error) 235 goto failed; 236 237 return; 238 239 failed: 240 aprint_error_dev(sc->sc_dev, "couldn't create sysctl nodes: %d\n", error); 241 sysctl_teardown(&log); 242 } 243 244 static void 245 pwm_backlight_display_on(device_t dev) 246 { 247 struct pwm_backlight_softc * const sc = device_private(dev); 248 249 pwm_enable(sc->sc_pwm); 250 } 251 252 static void 253 pwm_backlight_display_off(device_t dev) 254 { 255 struct pwm_backlight_softc * const sc = device_private(dev); 256 257 pwm_disable(sc->sc_pwm); 258 } 259 260 static void 261 pwm_backlight_display_brightness_up(device_t dev) 262 { 263 struct pwm_backlight_softc * const sc = device_private(dev); 264 u_int n; 265 266 n = pwm_backlight_get(sc); 267 if (n < sc->sc_nlevels - 1) 268 pwm_backlight_set(sc, n + 1); 269 } 270 271 static void 272 pwm_backlight_display_brightness_down(device_t dev) 273 { 274 struct pwm_backlight_softc * const sc = device_private(dev); 275 u_int n; 276 277 n = pwm_backlight_get(sc); 278 if (n > 0) 279 pwm_backlight_set(sc, n - 1); 280 } 281 282 static void 283 pwm_backlight_pmf_init(struct pwm_backlight_softc *sc) 284 { 285 pmf_event_register(sc->sc_dev, PMFE_DISPLAY_ON, 286 pwm_backlight_display_on, true); 287 pmf_event_register(sc->sc_dev, PMFE_DISPLAY_OFF, 288 pwm_backlight_display_off, true); 289 pmf_event_register(sc->sc_dev, PMFE_DISPLAY_BRIGHTNESS_UP, 290 pwm_backlight_display_brightness_up, true); 291 pmf_event_register(sc->sc_dev, PMFE_DISPLAY_BRIGHTNESS_DOWN, 292 pwm_backlight_display_brightness_down, true); 293 } 294
Indexes created Mon Sep 29 21:09:56 GMT 2025