ambarella: detect the SoC from the machine string

.github/workflows/pr-build-check.yml

@@ -147,7 +147,8 @@ jobs:
         run: |
           cmake -H. -Bbuild -DCMAKE_BUILD_TYPE=Release
           cmake --build build --target cYAML_test reginfo_test longse_test \
-                                      sensors_test anyka_test hal_hisi_test \
+                                      sensors_test anyka_test ambarella_test \
+                                      hal_hisi_test \
                                       report_test http_test mtd_alias_test \
                                       nand_layout_test upgrade_env_test \
                                       jffs2_test raw_image_test
@@ -162,6 +163,7 @@ jobs:
           ./build/reginfo_test
           ./build/longse_test
           ./build/anyka_test
+          ./build/ambarella_test
           ./build/hal_hisi_test
           # Run from the tree root: the fingerprint it compares against is
           # src/sensors_golden.txt, and a sensor that stopped being identified

CLAUDE.md

@@ -126,6 +126,8 @@ CMake knobs worth knowing:
   purpose. Same situation as `longse_test` and the same `CHECK` macro: nobody
   on the project has an Anyka camera, so this is all the verification that
   code gets until a reporter runs it.
+- `./build/ambarella_test`: the `/proc/cpuinfo` machine string the Ambarella
+  HAL parses, same `CHECK` macro and same reason.
 - `tools/test_pipeline.sh`: hardware-free end-to-end check of the sensor
   driver extraction pipeline (`trace_segment.py` -> `trace_to_driver.py` ->
   `gcc -fsyntax-only` -> `trace_diff.py`), plus the `--selftest` of every
@@ -213,6 +215,14 @@ with. Reading the register is therefore a refinement and never the gate, which
 is also what lets detection survive a kernel that will not hand over
 `/dev/mem`.
 
+Ambarella (`src/hal/ambarella.c`) stops at the machine string on purpose. The
+exact part (S3L33M, S3L55M, S3L66, ...) is a word the DSP firmware writes,
+reachable only through `/dev/iav`, so the report says `S3L`. Do not derive
+total RAM from the boot log's `IAVMEM` line: Amboot computes it from a
+compile-time `DRAM_SIZE`, and #266 has it ending at 512 MiB on a camera
+reported as 256 MiB. That Dahua kernel also refuses `execve()` from writable
+filesystems, so `/tmp/ipctool` fails there with "Success" and exit code 2.
+
 Sensor I2C addresses in tables are the 8-bit (write) form; the default
 `i2c_change_addr` shifts right by one for the kernel, and some HALs install
 `i2c_change_plain_addr` instead. Ingenic gates the sensor clock, which is why

CMakeLists.txt

@@ -51,7 +51,7 @@ include_directories(./src/)
 # directly rather than through the table. Affects libipchw only; the ipctool
 # executable is a diagnostic tool and always carries every vendor.
 set(IPCHW_OPTIONAL_VENDORS
-    allwinner anyka bcm fh gm ingenic novatek rockchip sstar tegra xilinx xm)
+    allwinner ambarella anyka bcm fh gm ingenic novatek rockchip sstar tegra xilinx xm)
 set(IPCHW_VENDORS "all" CACHE STRING
     "Vendor HALs to compile into libipchw: 'all', 'none', or a ;-separated \
 subset of: ${IPCHW_OPTIONAL_VENDORS}")
@@ -525,6 +525,13 @@ if(NOT ONLY_LIBRARY)
   target_include_directories(anyka_test PRIVATE include src)
   target_link_libraries(anyka_test m Threads::Threads)
 
+  # Same reason as anyka_test: the parser is all that can run off a camera.
+  add_executable(ambarella_test src/hal/ambarella_test.c src/hal/ambarella.c
+                                src/hal/common.c src/tools.c src/cjson/cJSON.c
+                                ${VERSION_OBJ})
+  target_include_directories(ambarella_test PRIVATE include src)
+  target_link_libraries(ambarella_test m Threads::Threads)
+
   # The body `ipctool upload` sends: part framing, the backup's layout and
   # the length that must match it, and openipc.org's answer. Off a camera,
   # like the others.

src/chipid.c

@@ -74,6 +74,9 @@ static const manufacturers_t manufacturers[] = {
 #ifdef IPCHW_VENDOR_FH
     {"FH", fh_detect_cpu, VENDOR_FH, fh_setup_hal},
 #endif
+#ifdef IPCHW_VENDOR_AMBARELLA
+    {"Ambarella", ambarella_detect_cpu, VENDOR_AMBARELLA, ambarella_setup_hal},
+#endif
 #ifdef IPCHW_VENDOR_ANYKA
     {NULL /* Generic */, anyka_detect_cpu, VENDOR_ANYKA, anyka_setup_hal},
 #endif

src/chipid.h

@@ -4,6 +4,7 @@
 #include <stdbool.h>
 
 #define VENDOR_ALLWINNER "Allwinner"
+#define VENDOR_AMBARELLA "Ambarella"
 #define VENDOR_ANYKA "Anyka"
 #define VENDOR_BCM "Broadcom"
 #define VENDOR_FH "Fullhan"

src/hal/ambarella.c

@@ -0,0 +1,54 @@
+#include "hal/ambarella.h"
+
+#include <string.h>
+
+#include "hal/common.h"
+#include "tools.h"
+
+/* Defaults of the `addr` module parameter across the S3L SDK's VIN drivers,
+ * the 8-bit form ipctool's tables use. AR0521 is the one part left out: it
+ * answers on 0x6C, and the onsemi probe runs before the OmniVision one, so
+ * listing it would have that probe reading an OV4689. */
+static unsigned char sony_addrs[] = {0x34, 0};
+static unsigned char onsemi_addrs[] = {0x20, 0};
+static unsigned char omni_addrs[] = {0x6c, 0};
+
+static sensor_addr_t ambarella_possible_i2c_addrs[] = {
+    {SENSOR_SONY, sony_addrs},
+    {SENSOR_ONSEMI, onsemi_addrs},
+    {SENSOR_OMNIVISION, omni_addrs},
+    {0, NULL}};
+
+/* Every DT_MACHINE_START in the vendor tree reads "Ambarella <soc> (Flattened
+ * Device Tree)". These kernels register no UART with /proc/iomem, and S3L
+ * and S3LM share one machine string: the exact part (33M, 55M, 66, ...) is
+ * known only to the DSP firmware once it runs, so "S3L" is as far as this
+ * goes. */
+bool ambarella_machine_name(const char *cpuinfo, char *out, size_t outlen) {
+    if (!outlen)
+        return false;
+
+    if (!line_from_file(cpuinfo, "Hardware.+: Ambarella ([A-Za-z0-9]+)", out,
+                        outlen))
+        return false;
+
+    out[outlen - 1] = '\0';
+    return true;
+}
+
+bool ambarella_detect_cpu(char *chip_name) {
+    char machine[128];
+
+    if (!ambarella_machine_name("/proc/cpuinfo", machine, sizeof(machine)))
+        return false;
+    strcpy(chip_name, machine);
+
+    /* chip_generation stays 0 on purpose. It keys the pad-mux, clock and boot
+     * ROM tables, and ipctool has none for Ambarella, so 0 sends those paths to
+     * their no-table answer and getchipfamily() back to the name. */
+    return true;
+}
+
+void ambarella_setup_hal() {
+    possible_i2c_addrs = ambarella_possible_i2c_addrs;
+}

src/hal/ambarella.h

@@ -0,0 +1,11 @@
+#ifndef HAL_AMBARELLA_H
+#define HAL_AMBARELLA_H
+
+#include <stdbool.h>
+#include <stddef.h>
+
+bool ambarella_machine_name(const char *cpuinfo, char *out, size_t outlen);
+bool ambarella_detect_cpu(char *chip_name);
+void ambarella_setup_hal();
+
+#endif /* HAL_AMBARELLA_H */

src/hal/ambarella_test.c

@@ -0,0 +1,69 @@
+/* Hardware-free cover for the Ambarella machine-string parser. The strings
+ * are the DT_MACHINE_START names in the vendor kernel, and the S3L cpuinfo is
+ * the one from issue #266. */
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <unistd.h>
+
+#include "hal/ambarella.h"
+
+int chip_generation;
+char chip_name[128];
+const char *getchipfamily() { return chip_name; }
+
+static int failures;
+
+#define CHECK(cond)                                                            \
+    do {                                                                       \
+        if (!(cond)) {                                                         \
+            fprintf(stderr, "  FAIL %s:%d: %s\n", __FILE__, __LINE__, #cond);  \
+            failures++;                                                        \
+        }                                                                      \
+    } while (0)
+
+static bool parse(const char *cpuinfo, char *out, size_t outlen) {
+    char path[] = "/tmp/ambarella_test.XXXXXX";
+    int fd = mkstemp(path);
+
+    CHECK(fd >= 0);
+    CHECK(write(fd, cpuinfo, strlen(cpuinfo)) == (ssize_t)strlen(cpuinfo));
+    close(fd);
+    bool res = ambarella_machine_name(path, out, outlen);
+    unlink(path);
+    return res;
+}
+
+int main() {
+    char buf[128];
+
+    CHECK(parse("processor\t: 0\n"
+                "Hardware\t: Ambarella S3L (Flattened Device Tree)\n"
+                "Revision\t: 0000\n",
+                buf, sizeof(buf)));
+    CHECK(!strcmp(buf, "S3L"));
+
+    CHECK(parse("Hardware\t: Ambarella S2L (Flattened Device Tree)\n", buf,
+                sizeof(buf)));
+    CHECK(!strcmp(buf, "S2L"));
+
+    CHECK(parse("Hardware\t: Ambarella A5S (Flattened Device Tree)\n", buf,
+                sizeof(buf)));
+    CHECK(!strcmp(buf, "A5S"));
+
+    CHECK(!parse("Hardware\t: SStar Soc (Flattened Device Tree)\n", buf,
+                 sizeof(buf)));
+    CHECK(!parse("model name\t: ARMv7 Processor rev 1 (v7l)\n", buf,
+                 sizeof(buf)));
+
+    /* Nothing may land in the buffer, or just before it. */
+    char guarded[3] = {'x', 'y', 'z'};
+    CHECK(!parse("Hardware\t: Ambarella S3L (Flattened Device Tree)\n",
+                 guarded + 1, 0));
+    CHECK(guarded[0] == 'x' && guarded[1] == 'y' && guarded[2] == 'z');
+
+    if (failures)
+        return EXIT_FAILURE;
+    puts("ambarella_test: all cases passed");
+    return EXIT_SUCCESS;
+}

src/hal/common.h

@@ -8,6 +8,7 @@
 
 #include "cjson/cJSON.h"
 #include "hal/allwinner.h"
+#include "hal/ambarella.h"
 #include "hal/anyka.h"
 #include "hal/bcm.h"
 #include "hal/fh.h"