pwm_backlight.c revision 1.3
1 /* $NetBSD: pwm_backlight.c,v 1.3 2018/05/07 12:58:58 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 1.3 2018/05/07 12:58:58 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 fdtbus_gpio_write(sc->sc_pin, 1); 104 } 105 106 levels = fdtbus_get_prop(phandle, "brightness-levels", &len); 107 if (len < 4) { 108 aprint_error(": couldn't get 'brightness-levels' property\n"); 109 return; 110 } 111 sc->sc_levels = kmem_alloc(len, KM_SLEEP); 112 sc->sc_nlevels = len / 4; 113 for (n = 0; n < sc->sc_nlevels; n++) 114 sc->sc_levels[n] = be32toh(levels[n]); 115 116 aprint_naive("\n"); 117 aprint_normal(": PWM Backlight"); 118 aprint_verbose(" <"); 119 for (n = 0; n < sc->sc_nlevels; n++) { 120 aprint_verbose("%s%u", n ? " " : "", sc->sc_levels[n]); 121 } 122 aprint_verbose(">"); 123 aprint_normal("\n"); 124 125 if (of_getprop_uint32(phandle, "default-brightness-level", &default_level) == 0) { 126 /* set the default level now */ 127 pwm_backlight_set(sc, default_level); 128 } 129 130 pwm_backlight_sysctl_init(sc); 131 pwm_backlight_pmf_init(sc); 132 } 133 134 static void 135 pwm_backlight_set(struct pwm_backlight_softc *sc, u_int index) 136 { 137 struct pwm_config conf; 138 139 if (index >= sc->sc_nlevels) 140 return; 141 142 aprint_debug_dev(sc->sc_dev, "set duty cycle to %u%%\n", sc->sc_levels[index]); 143 144 pwm_disable(sc->sc_pwm); 145 pwm_get_config(sc->sc_pwm, &conf); 146 conf.duty_cycle = (conf.period * sc->sc_levels[index]) / sc->sc_levels[sc->sc_nlevels - 1]; 147 pwm_set_config(sc->sc_pwm, &conf); 148 pwm_enable(sc->sc_pwm); 149 } 150 151 static u_int 152 pwm_backlight_get(struct pwm_backlight_softc *sc) 153 { 154 struct pwm_config conf; 155 u_int raw_val, n; 156 157 pwm_get_config(sc->sc_pwm, &conf); 158 159 raw_val = (conf.duty_cycle * sc->sc_levels[sc->sc_nlevels - 1]) / conf.period; 160 161 /* Return the closest setting to the raw value */ 162 for (n = 0; n < sc->sc_nlevels; n++) { 163 if (raw_val <= sc->sc_levels[n]) 164 break; 165 } 166 return n; 167 } 168 169 static int 170 pwm_backlight_sysctl_helper(SYSCTLFN_ARGS) 171 { 172 struct pwm_backlight_softc * const sc = rnode->sysctl_data; 173 struct sysctlnode node; 174 int error; 175 u_int level, n; 176 177 node = *rnode; 178 node.sysctl_data = &level; 179 180 n = pwm_backlight_get(sc); 181 level = sc->sc_levels[n]; 182 183 error = sysctl_lookup(SYSCTLFN_CALL(&node)); 184 if (error || newp == NULL) 185 return error; 186 187 for (n = 0; n < sc->sc_nlevels; n++) { 188 if (sc->sc_levels[n] == level) { 189 pwm_backlight_set(sc, n); 190 return 0; 191 } 192 } 193 194 return EINVAL; 195 } 196 197 static void 198 pwm_backlight_sysctl_init(struct pwm_backlight_softc *sc) 199 { 200 const struct sysctlnode *node, *pwmnode; 201 struct sysctllog *log = NULL; 202 int error; 203 u_int n; 204 205 sc->sc_levelstr = kmem_zalloc(strlen("XXXXX ") * sc->sc_nlevels, KM_SLEEP); 206 for (n = 0; n < sc->sc_nlevels; n++) { 207 char buf[7]; 208 snprintf(buf, sizeof(buf), n ? " %u" : "%u", sc->sc_levels[n]); 209 strcat(sc->sc_levelstr, buf); 210 } 211 212 error = sysctl_createv(&log, 0, NULL, &node, 213 CTLFLAG_PERMANENT, CTLTYPE_NODE, "hw", NULL, 214 NULL, 0, NULL, 0, CTL_HW, CTL_EOL); 215 if (error) 216 goto failed; 217 218 error = sysctl_createv(&log, 0, &node, &pwmnode, 219 0, CTLTYPE_NODE, device_xname(sc->sc_dev), NULL, 220 NULL, 0, NULL, 0, CTL_CREATE, CTL_EOL); 221 if (error) 222 goto failed; 223 224 error = sysctl_createv(&log, 0, &pwmnode, NULL, 225 0, CTLTYPE_STRING, "levels", NULL, 226 NULL, 0, sc->sc_levelstr, 0, 227 CTL_CREATE, CTL_EOL); 228 if (error) 229 goto failed; 230 231 error = sysctl_createv(&log, 0, &pwmnode, NULL, 232 CTLFLAG_READWRITE, CTLTYPE_INT, "level", NULL, 233 pwm_backlight_sysctl_helper, 0, (void *)sc, 0, 234 CTL_CREATE, CTL_EOL); 235 if (error) 236 goto failed; 237 238 return; 239 240 failed: 241 aprint_error_dev(sc->sc_dev, "couldn't create sysctl nodes: %d\n", error); 242 sysctl_teardown(&log); 243 } 244 245 static void 246 pwm_backlight_display_on(device_t dev) 247 { 248 struct pwm_backlight_softc * const sc = device_private(dev); 249 250 if (sc->sc_pin) 251 fdtbus_gpio_write(sc->sc_pin, 1); 252 } 253 254 static void 255 pwm_backlight_display_off(device_t dev) 256 { 257 struct pwm_backlight_softc * const sc = device_private(dev); 258 259 if (sc->sc_pin) 260 fdtbus_gpio_write(sc->sc_pin, 0); 261 } 262 263 static void 264 pwm_backlight_display_brightness_up(device_t dev) 265 { 266 struct pwm_backlight_softc * const sc = device_private(dev); 267 u_int n; 268 269 n = pwm_backlight_get(sc); 270 if (n < sc->sc_nlevels - 1) 271 pwm_backlight_set(sc, n + 1); 272 } 273 274 static void 275 pwm_backlight_display_brightness_down(device_t dev) 276 { 277 struct pwm_backlight_softc * const sc = device_private(dev); 278 u_int n; 279 280 n = pwm_backlight_get(sc); 281 if (n > 0) 282 pwm_backlight_set(sc, n - 1); 283 } 284 285 static void 286 pwm_backlight_pmf_init(struct pwm_backlight_softc *sc) 287 { 288 pmf_event_register(sc->sc_dev, PMFE_DISPLAY_ON, 289 pwm_backlight_display_on, true); 290 pmf_event_register(sc->sc_dev, PMFE_DISPLAY_OFF, 291 pwm_backlight_display_off, true); 292 pmf_event_register(sc->sc_dev, PMFE_DISPLAY_BRIGHTNESS_UP, 293 pwm_backlight_display_brightness_up, true); 294 pmf_event_register(sc->sc_dev, PMFE_DISPLAY_BRIGHTNESS_DOWN, 295 pwm_backlight_display_brightness_down, true); 296 } 297
Indexes created Tue Sep 30 06:09:59 GMT 2025