init

2026-08-14 13:49:01 +03:00
commit 563db09bf1
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+CC ?= cc
+CFLAGS ?= -O2 -Wall -Wextra
+PREFIX ?= /usr/local
+BINDIR ?= $(PREFIX)/bin
+INSTALL ?= install
+
+TARGET = nvbright
+SRC = nvbright.c
+
+.PHONY: all clean install uninstall
+
+all: $(TARGET)
+
+$(TARGET): $(SRC)
+	$(CC) $(CFLAGS) $(LDFLAGS) -o $@ $(SRC)
+
+install: $(TARGET)
+	$(INSTALL) -d $(DESTDIR)$(BINDIR)
+	$(INSTALL) -m 755 $(TARGET) $(DESTDIR)$(BINDIR)/$(TARGET)
+
+uninstall:
+	rm -f $(DESTDIR)$(BINDIR)/$(TARGET)
+
+clean:
+	rm -f $(TARGET) *.o
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+# NVbright: directly control NVIDIA-based LCD backlight brightness on Apple MacBook Air A1370
+
+NVbright is a lightweight utility for controlling LCD backlight brightness on NVIDIA-equipped Apple MacBooks running FreeBSD under EFI boot.
+
+## About
+
+On older NVIDIA-based Apple MacBooks (such as the MacBook Air A1370 with GeForce 320M, MCP89, or GT218 chipsets), LCD backlight level is modulated via a Pulse Width Modulation (PWM) signal generated by the GPU display engine (`PDISPLAY`).
+
+Under macOS or BIOS compatibility mode, firmware dynamically alters backlight brightness through System Management Interrupts (SMI) triggered by legacy I/O port writes. However, when booting FreeBSD natively in EFI mode, this legacy SMI path is unavailable, leaving the screen backlight stuck or uncontrollable via standard ACPI methods.
+
+`nvbright` addresses this by directly interacting with the GPU MMIO register BAR:
+
+1. Identifies the NVIDIA VGA controller's physical MMIO BAR0 address dynamically using `/usr/sbin/pciconf`.
+2. Maps the register space into memory via `/dev/mem` using `mmap(2)`.
+3. Detects the active Serial Output Router (SOR) with an initialized PWM divisor (`PWM_DIV`).
+4. Reads and computes current duty cycle or writes new values latching the display engine registers (`PWM_CTL`).
+
+The register mapping and control logic mirror the Linux `nouveau` driver implementation for NV50 and NVA3 chip architectures:
+
+- `NV50_PDISP_SOR_PWM_DIV(i) = 0x0061c080 + i * 0x800`
+- `NV50_PDISP_SOR_PWM_CTL(i) = 0x0061c084 + i * 0x800`
+- `CTL_NEW (0x80000000)`: Latch/apply updated brightness value
+- `CTL_UNK (0x40000000)`: Required control flag on NVA3-class chipsets
+
+## Build
+
+`nvbright` is written in standard C and relies only on standard POSIX and FreeBSD system headers (`sys/mman.h`, `sys/types.h`, `fcntl.h`, `unistd.h`). No external dependencies or third-party libraries are required.
+
+Compile using `make`:
+
+```sh
+make
+```
+
+Or compile manually using `clang` / `cc`:
+
+```sh
+cc -O2 -Wall -Wextra -o nvbright nvbright.c
+```
+
+To install the binary system-wide to `/usr/local/bin` (respects `PREFIX` and `DESTDIR`):
+
+```sh
+sudo make install
+```
+
+## Usage
+
+Because `nvbright` requires direct access to `/dev/mem` to map GPU MMIO registers and executes `/usr/sbin/pciconf`, it must be run as root (e.g., with `sudo` or `doas`).
+
+### Command Syntax
+
+```sh
+nvbright <get|set|up|down> [value 0-100]
+```
+
+### Commands
+
+- **`get`**: Queries the hardware and prints the current brightness level (percentage from 0 to 100), active SOR index, and PWM divisor.
+  ```sh
+  sudo nvbright get
+  ```
+  *Example Output:*
+  ```text
+  Brightness: 65 / 100  (SOR1, pwm_div=1024)
+  ```
+
+- **`set <0-100>`**: Sets the display backlight directly to the specified percentage value.
+  ```sh
+  sudo nvbright set 75
+  ```
+  *Example Output:*
+  ```text
+  Set brightness: 75 / 100
+  ```
+
+- **`up`**: Increases brightness by 10% (clamped at 100%).
+  ```sh
+  sudo nvbright up
+  ```
+
+- **`down`**: Decreases brightness by 10% (clamped at 0%).
+  ```sh
+  sudo nvbright down
+  ```
+
+### Desktop and Window Manager Integration
+
+You can bind `nvbright up` and `nvbright down` commands to the brightness keys (`XF86MonBrightnessUp` and `XF86MonBrightnessDown`) in window manager configurations (such as Sway, i3, or Openbox) or configure `sudoers` / `doas.conf` rules to allow execution without password prompts.
+
+## Credits
+
+Created by Luxferre in 2026, released into the public domain with no warranties.
+
+Hardware register specifications and control flow inspired by the Linux `nouveau` DRM backlight driver (`nv50` / `nva3`).
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+/*
+ * nvbright - NVIDIA GPU backlight control for Apple MacBooks (FreeBSD)
+ *
+ * On NVIDIA-based Apple hardware (e.g. MacBook Air A1370 / GeForce 320M,
+ * MCP89 / GT218) the LCD backlight is driven by a PWM signal generated by
+ * the GPU's display engine (PDISPLAY).  The firmware normally reprograms it
+ * through an SMI triggered by legacy I/O ports, but that path is dead under
+ * FreeBSD (EFI boot), so we program the GPU MMIO PWM registers directly.
+ * This mirrors the Linux nouveau nv50 / nva3 backlight driver:
+ *
+ *   NV50_PDISP_SOR_PWM_DIV(i) = 0x0061c080 + i * 0x800
+ *   NV50_PDISP_SOR_PWM_CTL(i) = 0x0061c084 + i * 0x800
+ *   CTL_NEW = 0x80000000   (latch / apply new value)
+ *   CTL_UNK = 0x40000000   (required on nva3-class chips)
+ *
+ * The backlight SOR is located at runtime (the one with a programmed
+ * PWM_DIV), and the GPU's MMIO register BAR is mapped via /dev/mem.
+ * Requires root to run.
+ * 
+ * Created by Luxferre in 2026, released into the public domain.
+ */
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <stdint.h>
+#include <fcntl.h>
+#include <unistd.h>
+#include <string.h>
+#include <errno.h>
+#include <sys/mman.h>
+#include <sys/types.h>
+
+#define PWM_DIV(i) (0x0061c080UL + (i) * 0x800UL)
+#define PWM_CTL(i) (0x0061c084UL + (i) * 0x800UL)
+#define CTL_NEW   0x80000000u
+#define CTL_UNK   0x40000000u
+#define MAX_SOR   8
+#define STEP      10
+#define FIXED_DIV 1025u   /* used only if no SOR has a programmed PWM_DIV */
+
+static int g_memfd = -1;
+static volatile uint32_t *g_bar;
+static int g_sor = -1;
+static uint32_t g_div;
+
+static void die(const char *msg) {
+  fprintf(stderr, "nvbright: %s: %s\n", msg, strerror(errno));
+  exit(1);
+}
+
+static uint32_t rd(uint32_t off) { return g_bar[off / 4]; }
+static void wr(uint32_t off, uint32_t v) { g_bar[off / 4] = v; }
+
+/* Locate the NVIDIA VGA device's MMIO register BAR (BAR0) via pciconf. */
+static void locate_bar(uint64_t *base, uint64_t *size) {
+  FILE *fp = popen("/usr/sbin/pciconf -l -b", "r");
+  if(!fp) die("popen /usr/sbin/pciconf");
+  char line[1024];
+  int in_nv = 0;
+  *base = 0; *size = 0;
+  while(fgets(line, sizeof(line), fp)) {
+    if(line[0] != ' ' && line[0] != '\t') {
+      in_nv = (strstr(line, "vendor=0x10de") &&
+               (strstr(line, "class=0x030000") || strstr(line, "vgapci")));
+      continue;
+    }
+    if(!in_nv) continue;
+    if(strstr(line, "bar") && strstr(line, "[10]")) {
+      char *b = strstr(line, "base");
+      char *s = strstr(line, "size");
+      unsigned long long bb = 0, sz = 0;
+      if(b) sscanf(b, "base 0x%llx", &bb);
+      if(s) sscanf(s, "size %llu", &sz);
+      *base = (uint64_t)bb;
+      *size = (uint64_t)sz;
+      break;
+    }
+  }
+  pclose(fp);
+  if(!*base) die("could not locate NVIDIA GPU MMIO BAR (is this an nvidia vga?)");
+}
+
+/* Pick the SOR whose PWM the firmware already programmed (the backlight). */
+static void detect_sor(void) {
+  for(int i = 0; i < MAX_SOR; i++) {
+    uint32_t div = rd(PWM_DIV(i));
+    if(div != 0) { g_sor = i; g_div = div; return; }
+  }
+  g_sor = 0;          /* fallback: nv50-style fixed period on SOR0 */
+  g_div = 0;
+}
+
+static int bl_get(void) {
+  uint32_t ctl = rd(PWM_CTL(g_sor));
+  uint32_t val = ctl & 0x00ffffffu;
+  uint32_t div = g_div ? g_div : FIXED_DIV;
+  long lvl = ((long)val * 100 + (long)(div / 2)) / (long)div;
+  if(lvl < 0) lvl = 0;
+  if(lvl > 100) lvl = 100;
+  return (int)lvl;
+}
+
+static void bl_set(int level) {
+  if(level < 0) level = 0;
+  if(level > 100) level = 100;
+  uint32_t div = g_div ? g_div : FIXED_DIV;
+  uint32_t val = (uint32_t)(((uint64_t)level * div) / 100);
+  wr(PWM_DIV(g_sor), div);
+  wr(PWM_CTL(g_sor), val | CTL_NEW | CTL_UNK);
+}
+
+int main(int argc, char **argv) {
+  if(argc < 2) {
+    fprintf(stderr, "Usage: %s <get|set|up|down> [value 0-100]\n", argv[0]);
+    fprintf(stderr, "  get            print current brightness (0-100)\n");
+    fprintf(stderr, "  set <0-100>    set brightness\n");
+    fprintf(stderr, "  up / down      step brightness by %d\n", STEP);
+    return 1;
+  }
+
+  uint64_t base = 0, size = 0;
+  locate_bar(&base, &size);
+  if(size == 0) size = 0x1000000UL;
+
+  g_memfd = open("/dev/mem", O_RDWR);
+  if(g_memfd < 0) die("open /dev/mem (must run as root)");
+  void *m = mmap(NULL, size, PROT_READ | PROT_WRITE, MAP_SHARED, g_memfd, (off_t)base);
+  if(m == MAP_FAILED) die("mmap /dev/mem");
+  g_bar = (volatile uint32_t *)m;
+
+  detect_sor();
+
+  if(strcmp(argv[1], "get") == 0) {
+    printf("Brightness: %d / 100  (SOR%d, pwm_div=%u)\n",
+           bl_get(), g_sor, g_div ? g_div : FIXED_DIV);
+  } else if(strcmp(argv[1], "set") == 0 && argc >= 3) {
+    bl_set(atoi(argv[2]));
+    printf("Set brightness: %d / 100\n", bl_get());
+  } else if(strcmp(argv[1], "up") == 0) {
+    int v = bl_get() + STEP; if(v > 100) v = 100;
+    bl_set(v);
+    printf("Brightness up: %d / 100\n", bl_get());
+  } else if(strcmp(argv[1], "down") == 0) {
+    int v = bl_get() - STEP; if(v < 0) v = 0;
+    bl_set(v);
+    printf("Brightness down: %d / 100\n", bl_get());
+  } else {
+    fprintf(stderr, "Unknown command: %s\n", argv[1]);
+    return 1;
+  }
+  return 0;
+}