soc: apple: rtkit: Add RTKit IPC library

Apple SoCs such as the M1 come with multiple embedded co-processors
running proprietary firmware. Communication with those is established
over a simple mailbox using the RTKit IPC protocol.

Signed-off-by: Sven Peter <sven@svenpeter.dev>

drivers/soc/apple/Kconfig

@@ -17,6 +17,18 @@ config APPLE_PMGR_PWRSTATE
 	  controls for SoC devices. This driver manages them through the
 	  generic power domain framework, and also provides reset support.
 
+config APPLE_RTKIT
+	tristate "Apple RTKit co-processor IPC protocol"
+	depends on MAILBOX && (ARCH_APPLE || COMPILE_TEST)
+	default ARCH_APPLE
+	help
+	  Apple SoCs such as the M1 come with various co-processors running
+	  their proprietary RTKit operating system. This option enables support
+	  for the protocol library used to communicate with those. It is used
+	  by various client drivers.
+
+	  Say 'y' here if you have an Apple SoC.
+
 config APPLE_SART
 	tristate "Apple SART DMA address filter"
 	depends on ARCH_APPLE || COMPILE_TEST

drivers/soc/apple/Makefile

@@ -1,5 +1,8 @@
 # SPDX-License-Identifier: GPL-2.0-only
 obj-$(CONFIG_APPLE_PMGR_PWRSTATE)	+= apple-pmgr-pwrstate.o
 
+obj-$(CONFIG_APPLE_RTKIT) += apple-rtkit.o
+apple-rtkit-y = rtkit.o rtkit-crashlog.o
+
 obj-$(CONFIG_APPLE_SART) += apple-sart.o
 apple-sart-y = sart.o

drivers/soc/apple/rtkit-crashlog.c

@@ -0,0 +1,142 @@
+#include "rtkit-internal.h"
+
+#define FOURCC(a, b, c, d)                                                     \
+	(((u32)(a) << 24) | ((u32)(b) << 16) | ((u32)(c) << 8) | ((u32)(d)))
+
+#define APPLE_RTKIT_CRASHLOG_HEADER FOURCC('C', 'L', 'H', 'E')
+#define APPLE_RTKIT_CRASHLOG_STR FOURCC('C', 's', 't', 'r')
+#define APPLE_RTKIT_CRASHLOG_VERSION FOURCC('C', 'v', 'e', 'r')
+#define APPLE_RTKIT_CRASHLOG_MBOX FOURCC('C', 'm', 'b', 'x')
+#define APPLE_RTKIT_CRASHLOG_TIME FOURCC('C', 't', 'i', 'm')
+
+struct apple_rtkit_crashlog_header {
+	u32 fourcc;
+	u32 version;
+	u32 size;
+	u32 flags;
+	u8 _unk[16];
+};
+static_assert(sizeof(struct apple_rtkit_crashlog_header) == 0x20);
+
+struct apple_rtkit_crashlog_mbox_entry {
+	u64 msg0;
+	u64 msg1;
+	u32 timestamp;
+	u8 _unk[4];
+};
+static_assert(sizeof(struct apple_rtkit_crashlog_mbox_entry) == 0x18);
+
+static void apple_rtkit_crashlog_dump_str(struct apple_rtkit *rtk, u8 *bfr,
+					  size_t size)
+{
+	u32 idx;
+	u8 *ptr, *end;
+
+	memcpy(&idx, bfr, 4);
+
+	ptr = bfr + 4;
+	end = bfr + size;
+	while (ptr < end) {
+		u8 *newline = memchr(ptr, '\n', end - ptr);
+
+		if (newline) {
+			u8 tmp = *newline;
+			*newline = '\0';
+			rtk_warn("Message (id=%x): %s\n", idx, ptr);
+			*newline = tmp;
+			ptr = newline + 1;
+		} else {
+			rtk_warn("Message (id=%x): %s", idx, ptr);
+			break;
+		}
+	}
+}
+
+static void apple_rtkit_crashlog_dump_version(struct apple_rtkit *rtk, u8 *bfr,
+					      size_t size)
+{
+	rtk_warn("Version: %s", bfr + 16);
+}
+
+static void apple_rtkit_crashlog_dump_time(struct apple_rtkit *rtk, u8 *bfr,
+					      size_t size)
+{
+	u64 crash_time;
+
+	memcpy(&crash_time, bfr, 8);
+	rtk_warn("Crash time: %lld", crash_time);
+}
+
+static void apple_rtkit_crashlog_dump_mailbox(struct apple_rtkit *rtk, u8 *bfr,
+					      size_t size)
+{
+	u32 type, index, i;
+	size_t n_messages;
+	struct apple_rtkit_crashlog_mbox_entry entry;
+
+	memcpy(&type, bfr + 16, 4);
+	memcpy(&index, bfr + 24, 4);
+	n_messages = (size - 28) / sizeof(entry);
+
+	rtk_warn("Mailbox history (type = %d, index = %d)", type, index);
+	for (i = 0; i < n_messages; ++i) {
+		memcpy(&entry, bfr + 28 + i * sizeof(entry), sizeof(entry));
+		rtk_warn(" #%03d@%08x: %016llx %016llx", i, entry.timestamp,
+			 entry.msg0, entry.msg1);
+	}
+}
+
+void apple_rtkit_crashlog_dump(struct apple_rtkit *rtk, u8 *bfr, size_t size)
+{
+	size_t offset;
+	u32 section_fourcc, section_size;
+	struct apple_rtkit_crashlog_header header;
+
+	memcpy(&header, bfr, sizeof(header));
+	if (header.fourcc != APPLE_RTKIT_CRASHLOG_HEADER) {
+		rtk_warn("Expected crashlog header but got %x", header.fourcc);
+		return;
+	}
+
+	if (header.size > size) {
+		rtk_warn("Crashlog size (%x) is too large", header.size);
+		return;
+	}
+
+	size = header.size;
+	offset = sizeof(header);
+
+	while (offset < size) {
+		memcpy(&section_fourcc, bfr + offset, 4);
+		memcpy(&section_size, bfr + offset + 12, 4);
+
+		switch (section_fourcc) {
+		case APPLE_RTKIT_CRASHLOG_HEADER:
+			rtk_dbg("End of crashlog reached");
+			return;
+		case APPLE_RTKIT_CRASHLOG_STR:
+			apple_rtkit_crashlog_dump_str(rtk, bfr + offset + 16,
+						      section_size);
+			break;
+		case APPLE_RTKIT_CRASHLOG_VERSION:
+			apple_rtkit_crashlog_dump_version(
+				rtk, bfr + offset + 16, section_size);
+			break;
+		case APPLE_RTKIT_CRASHLOG_MBOX:
+			apple_rtkit_crashlog_dump_mailbox(
+				rtk, bfr + offset + 16, section_size);
+			break;
+		case APPLE_RTKIT_CRASHLOG_TIME:
+			apple_rtkit_crashlog_dump_time(
+				rtk, bfr + offset + 16, section_size);
+			break;		
+		default:
+			rtk_warn("Unknown crashlog section: %x",
+				 section_fourcc);
+		}
+
+		offset += section_size;
+	}
+
+	rtk_warn("End of crashlog reached but no footer present");
+}

drivers/soc/apple/rtkit-internal.h

@@ -0,0 +1,70 @@
+#ifndef _APPLE_RTKIT_INTERAL_H
+#define _APPLE_RTKIT_INTERAL_H
+
+#include <linux/apple-mailbox.h>
+#include <linux/bitfield.h>
+#include <linux/bitmap.h>
+#include <linux/completion.h>
+#include <linux/dma-mapping.h>
+#include <linux/io.h>
+#include <linux/kthread.h>
+#include <linux/kfifo.h>
+#include <linux/mailbox_client.h>
+#include <linux/module.h>
+#include <linux/slab.h>
+#include <linux/soc/apple/rtkit.h>
+#include <linux/wait.h>
+
+#define rtk_err(format, arg...) dev_err(rtk->dev, "RTKit: " format, ##arg)
+#define rtk_warn(format, arg...) dev_warn(rtk->dev, "RTKit: " format, ##arg)
+#define rtk_info(format, arg...) dev_info(rtk->dev, "RTKit: " format, ##arg)
+#define rtk_dbg(format, arg...) dev_dbg(rtk->dev, "RTKit: " format, ##arg)
+
+
+#define APPLE_RTKIT_APP_ENDPOINT_START 0x20
+#define APPLE_RTKIT_MAX_ENDPOINTS 0x100
+
+struct apple_rtkit_work {
+	unsigned type;
+	struct apple_mbox_msg msg;
+};
+
+struct apple_rtkit {
+	void *cookie;
+	const struct apple_rtkit_ops *ops;
+	struct device *dev;
+	struct mbox_client mbox_cl;
+	struct mbox_chan *mbox_chan;
+
+	struct completion epmap_completion;
+	struct completion reinit_completion;
+	struct completion iop_pwr_ack_completion;
+	struct completion ap_pwr_ack_completion;
+
+	int boot_result;
+	int version;
+
+	unsigned iop_power_state;
+	unsigned ap_power_state;
+	bool crashed;
+
+	struct task_struct *task;
+
+	struct wait_queue_head wq;
+	DECLARE_KFIFO(work_fifo, struct apple_rtkit_work, 64);
+	spinlock_t work_lock;
+
+	DECLARE_BITMAP(endpoints, APPLE_RTKIT_MAX_ENDPOINTS);
+
+	struct apple_rtkit_shmem ioreport_buffer;
+	struct apple_rtkit_shmem crashlog_buffer;
+
+	struct apple_rtkit_shmem syslog_buffer;
+	char *syslog_msg_buffer;
+	size_t syslog_n_entries;
+	size_t syslog_msg_size;
+};
+
+void apple_rtkit_crashlog_dump(struct apple_rtkit *rtk, u8 *bfr, size_t size);
+
+#endif