| paul@0 | 1 | /* |
| paul@0 | 2 | * Access a SPI server to update a display panel backlight. |
| paul@0 | 3 | * This server is specific to the Ben NanoNote. |
| paul@0 | 4 | * |
| paul@0 | 5 | * (c) 2018 Paul Boddie <paul@boddie.org.uk> |
| paul@0 | 6 | * |
| paul@0 | 7 | * This program is free software; you can redistribute it and/or |
| paul@0 | 8 | * modify it under the terms of the GNU General Public License as |
| paul@0 | 9 | * published by the Free Software Foundation; either version 2 of |
| paul@0 | 10 | * the License, or (at your option) any later version. |
| paul@0 | 11 | * |
| paul@0 | 12 | * This program is distributed in the hope that it will be useful, |
| paul@0 | 13 | * but WITHOUT ANY WARRANTY; without even the implied warranty of |
| paul@0 | 14 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
| paul@0 | 15 | * GNU General Public License for more details. |
| paul@0 | 16 | * |
| paul@0 | 17 | * You should have received a copy of the GNU General Public License |
| paul@0 | 18 | * along with this program; if not, write to the Free Software |
| paul@0 | 19 | * Foundation, Inc., 51 Franklin Street, Fifth Floor, |
| paul@0 | 20 | * Boston, MA 02110-1301, USA |
| paul@0 | 21 | */ |
| paul@0 | 22 | |
| paul@0 | 23 | #include <l4/cxx/ipc_server> |
| paul@0 | 24 | #include <l4/re/env> |
| paul@0 | 25 | #include <l4/re/util/object_registry> |
| paul@0 | 26 | #include <l4/sys/capability> |
| paul@0 | 27 | |
| paul@0 | 28 | #include <stdlib.h> |
| paul@0 | 29 | |
| paul@0 | 30 | #include <l4/devices/spi-client.h> |
| paul@0 | 31 | #include "backlight-ops.h" |
| paul@0 | 32 | |
| paul@0 | 33 | /* SPI access abstractions. */ |
| paul@0 | 34 | |
| paul@0 | 35 | static L4::Cap<Spi_device_interface> spi_device; |
| paul@0 | 36 | |
| paul@0 | 37 | |
| paul@0 | 38 | |
| paul@0 | 39 | /* Backlight device. */ |
| paul@0 | 40 | |
| paul@0 | 41 | class Backlight_device_server : public L4::Server_object_t<L4::Kobject> |
| paul@0 | 42 | { |
| paul@0 | 43 | int _min = 55, _max = 90, _start = 70; |
| paul@0 | 44 | |
| paul@0 | 45 | void set_duty(int level) |
| paul@0 | 46 | { |
| paul@0 | 47 | level = level < _min ? _min : (level > _max ? _max : level); |
| paul@0 | 48 | |
| paul@0 | 49 | /* PWM_DUTY = R05h<5:3> = 5% increments from min to max */ |
| paul@0 | 50 | |
| paul@0 | 51 | int duty = ((level - _min) / 5) << 3; |
| paul@0 | 52 | |
| paul@0 | 53 | spi_device->send(16, 0x0516 | duty); /* R05h: GRB=0 (reset); PWM_DUTY=duty; SHDB2=1, SHDB1=1 (power-related); STB=0 (standby) */ |
| paul@0 | 54 | spi_device->send(16, 0x0546 | duty); /* R05h: GRB=1 (normal operation); ... */ |
| paul@0 | 55 | spi_device->send(16, 0x078d); /* R07h: HBLK=141 (horizontal blanking period from start of hsync pulse to data start) */ |
| paul@0 | 56 | spi_device->send(16, 0x1301); /* R13h: IN_SEL=1 (alignment mode) */ |
| paul@0 | 57 | spi_device->send(16, 0x0547 | duty); /* R05h: ...; STB=1 (not standby) */ |
| paul@0 | 58 | } |
| paul@0 | 59 | |
| paul@0 | 60 | public: |
| paul@0 | 61 | /* Dispatch incoming requests. */ |
| paul@0 | 62 | |
| paul@0 | 63 | int dispatch(l4_umword_t obj, L4::Ipc::Iostream &ios) |
| paul@0 | 64 | { |
| paul@0 | 65 | l4_msgtag_t tag; |
| paul@0 | 66 | int arg; |
| paul@0 | 67 | |
| paul@0 | 68 | (void) obj; |
| paul@0 | 69 | ios >> tag; |
| paul@0 | 70 | |
| paul@0 | 71 | switch (tag.label()) |
| paul@0 | 72 | { |
| paul@0 | 73 | case Backlight_op_disable: |
| paul@0 | 74 | disable(); |
| paul@0 | 75 | return L4_EOK; |
| paul@0 | 76 | |
| paul@0 | 77 | case Backlight_op_enable: |
| paul@0 | 78 | enable(); |
| paul@0 | 79 | return L4_EOK; |
| paul@0 | 80 | |
| paul@0 | 81 | case Backlight_op_set_brightness: |
| paul@0 | 82 | ios >> arg; |
| paul@0 | 83 | set_brightness(arg); |
| paul@0 | 84 | return L4_EOK; |
| paul@0 | 85 | |
| paul@0 | 86 | default: |
| paul@0 | 87 | return -L4_EBADPROTO; |
| paul@0 | 88 | } |
| paul@0 | 89 | } |
| paul@0 | 90 | |
| paul@0 | 91 | void disable() |
| paul@0 | 92 | { |
| paul@0 | 93 | spi_device->send(16, 0x055e); |
| paul@0 | 94 | } |
| paul@0 | 95 | |
| paul@0 | 96 | void enable() |
| paul@0 | 97 | { |
| paul@0 | 98 | set_duty(_start); |
| paul@0 | 99 | } |
| paul@0 | 100 | |
| paul@0 | 101 | /* Use the SPI device to update the brightness level. */ |
| paul@0 | 102 | |
| paul@0 | 103 | void set_brightness(int level) |
| paul@0 | 104 | { |
| paul@0 | 105 | level = level < _min ? _min : (level > _max ? _max : level); |
| paul@0 | 106 | spi_device->send(16, 0x0300 | level); /* R03h: brightness */ |
| paul@0 | 107 | } |
| paul@0 | 108 | }; |
| paul@0 | 109 | |
| paul@0 | 110 | static L4Re::Util::Registry_server<> server; |
| paul@0 | 111 | |
| paul@0 | 112 | |
| paul@0 | 113 | |
| paul@0 | 114 | int main(void) |
| paul@0 | 115 | { |
| paul@0 | 116 | /* Obtain a reference to the SPI device. */ |
| paul@0 | 117 | |
| paul@0 | 118 | spi_device = L4Re::Env::env()->get_cap<Spi_device_interface>("spi"); |
| paul@0 | 119 | if (!spi_device.is_valid()) return 1; |
| paul@0 | 120 | |
| paul@0 | 121 | /* Initialise and register a new server object. */ |
| paul@0 | 122 | |
| paul@0 | 123 | Backlight_device_server server_obj; |
| paul@0 | 124 | server.registry()->register_obj(&server_obj, "backlight"); |
| paul@0 | 125 | |
| paul@0 | 126 | /* Enter the IPC server loop. */ |
| paul@0 | 127 | |
| paul@0 | 128 | server.loop(); |
| paul@0 | 129 | return 0; |
| paul@0 | 130 | } |
