Re: [PATCH 08/10] HID: apple: Add DockChannel HID transport driver
From: Yureka Lilian
Date: Tue Jun 30 2026 - 09:28:07 EST
On 6/30/26 14:54, Michael Reeves via B4 Relay wrote:
From: Michael Reeves <michael.reeves077@xxxxxxxxx>If the keyboard appeared before stm, dchip->serial might be uninitialized.
Apple MTP exposes internal keyboard and trackpad interfaces over a HID
transport carried by DockChannel.
Add a transport driver that boots the MTP RTKit coprocessor, exchanges
HID packets through the DockChannel mailbox, and registers child HID
interfaces from devicetree.
Co-developed-by: Hector Martin <marcan@xxxxxxxxx>
Signed-off-by: Hector Martin <marcan@xxxxxxxxx>
Signed-off-by: Michael Reeves <michael.reeves077@xxxxxxxxx>
---
MAINTAINERS | 1 +
drivers/hid/Kconfig | 2 +
drivers/hid/Makefile | 2 +
drivers/hid/dockchannel/Kconfig | 15 +
drivers/hid/dockchannel/Makefile | 3 +
drivers/hid/dockchannel/apple-hid.c | 1130 +++++++++++++++++++++++++++++++++++
6 files changed, 1153 insertions(+)
diff --git a/MAINTAINERS b/MAINTAINERS
index ed68452c0ad6..0063276f0349 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -2620,6 +2620,7 @@ F: drivers/clk/clk-apple-nco.c
F: drivers/cpufreq/apple-soc-cpufreq.c
F: drivers/dma/apple-admac.c
F: drivers/gpio/gpio-macsmc.c
+F: drivers/hid/dockchannel/
F: drivers/hwmon/macsmc-hwmon.c
F: drivers/pmdomain/apple/
F: drivers/i2c/busses/i2c-pasemi-core.c
diff --git a/drivers/hid/Kconfig b/drivers/hid/Kconfig
index f9bcaeb66385..f27cda601ede 100644
--- a/drivers/hid/Kconfig
+++ b/drivers/hid/Kconfig
@@ -1488,6 +1488,8 @@ source "drivers/hid/surface-hid/Kconfig"
source "drivers/hid/intel-thc-hid/Kconfig"
+source "drivers/hid/dockchannel/Kconfig"
+
endif # HID
# USB support may be used with HID disabled
diff --git a/drivers/hid/Makefile b/drivers/hid/Makefile
index 23e6e3dd0c56..c9b4b1aff247 100644
--- a/drivers/hid/Makefile
+++ b/drivers/hid/Makefile
@@ -182,3 +182,5 @@ obj-$(CONFIG_AMD_SFH_HID) += amd-sfh-hid/
obj-$(CONFIG_SURFACE_HID_CORE) += surface-hid/
obj-$(CONFIG_INTEL_THC_HID) += intel-thc-hid/
+
+obj-$(CONFIG_APPLE_DOCKCHANNEL_HID) += dockchannel/
diff --git a/drivers/hid/dockchannel/Kconfig b/drivers/hid/dockchannel/Kconfig
new file mode 100644
index 000000000000..fca09ef74403
--- /dev/null
+++ b/drivers/hid/dockchannel/Kconfig
@@ -0,0 +1,15 @@
+# SPDX-License-Identifier: GPL-2.0-only OR MIT
+
+config APPLE_DOCKCHANNEL_HID
+ tristate "HID over Apple DockChannel"
+ depends on APPLE_DOCKCHANNEL
+ depends on APPLE_RTKIT
+ depends on HID
+ depends on INPUT
+ depends on OF
+ help
+ This provides a HID transport layer over the Apple DockChannel
+ mailbox interface. It is required to support the internal keyboard
+ and trackpad on M2 and later MacBook models.
+
+ Say Y here if you have an M2 or later Apple MacBook.
diff --git a/drivers/hid/dockchannel/Makefile b/drivers/hid/dockchannel/Makefile
new file mode 100644
index 000000000000..d1a82aa57a69
--- /dev/null
+++ b/drivers/hid/dockchannel/Makefile
@@ -0,0 +1,3 @@
+# SPDX-License-Identifier: GPL-2.0-only OR MIT
+
+obj-$(CONFIG_APPLE_DOCKCHANNEL_HID) += apple-hid.o
diff --git a/drivers/hid/dockchannel/apple-hid.c b/drivers/hid/dockchannel/apple-hid.c
new file mode 100644
index 000000000000..162fcfb5ab1c
--- /dev/null
+++ b/drivers/hid/dockchannel/apple-hid.c
@@ -0,0 +1,1130 @@
+// SPDX-License-Identifier: GPL-2.0-only OR MIT
+/*
+ * Apple DockChannel HID transport driver
+ *
+ * Copyright The Asahi Linux Contributors
+ */
+
+#include <linux/bitfield.h>
+#include <linux/completion.h>
+#include <linux/ctype.h>
+#include <linux/delay.h>
+#include <linux/device.h>
+#include <linux/dma-mapping.h>
+#include <linux/hid.h>
+#include <linux/mailbox/apple-dockchannel.h>
+#include <linux/mailbox_client.h>
+#include <linux/module.h>
+#include <linux/mutex.h>
+#include <linux/of.h>
+#include <linux/platform_device.h>
+#include <linux/property.h>
+#include <linux/slab.h>
+#include <linux/soc/apple/rtkit.h>
+#include <linux/spinlock.h>
+#include <linux/string.h>
+#include <linux/unaligned.h>
+#include <linux/workqueue.h>
+
+#define APPLE_ASC_CPU_CONTROL 0x44
+#define APPLE_ASC_CPU_CONTROL_RUN BIT(4)
+
+#define COMMAND_TIMEOUT_MS 1000
+#define START_TIMEOUT_MS 2000
+
+#define MAX_INTERFACES 16
+
+#define DCHID_MAX_PAYLOAD 0xffff
+#define DCHID_CHECKSUM_LEN 4
+#define DCHID_RX_BUF_SIZE (sizeof(struct dchid_hdr) + DCHID_MAX_PAYLOAD + \
+ DCHID_CHECKSUM_LEN)
+
+#define DCHID_CHANNEL_CMD 0x11
+#define DCHID_CHANNEL_REPORT 0x12
+#define DCHID_CHECKSUM_SEED 0xffffffff
+
+struct dchid_hdr {
+ u8 hdr_len;
+ u8 channel;
+ __le16 length;
+ u8 seq;
+ u8 iface;
+ __le16 pad;
+} __packed;
+
+#define IFACE_COMM 0
+
+#define FLAGS_GROUP GENMASK(7, 6)
+#define FLAGS_REQ GENMASK(5, 0)
+
+#define REQ_SET_REPORT 0
+#define REQ_GET_REPORT 1
+
+struct dchid_subhdr {
+ u8 flags;
+ u8 unk;
+ __le16 length;
+ __le32 retcode;
+} __packed;
+
+#define EVENT_INIT 0xf0
+#define EVENT_READY 0xf1
+
+struct dchid_init_hdr {
+ u8 type;
+ u8 unk1;
+ u8 unk2;
+ u8 iface;
+ char name[16];
+ u8 more_packets;
+ u8 unkpad;
+} __packed;
+
+#define INIT_HID_DESCRIPTOR 0
+#define INIT_TERMINATOR 2
+#define INIT_PRODUCT_NAME 7
+
+#define CMD_RESET_INTERFACE 0x40
+#define CMD_RESET_INTERFACE_SUB 1
+#define CMD_ENABLE_INTERFACE 0xb4
+
+struct dchid_init_block_hdr {
+ __le16 type;
+ __le16 length;
+} __packed;
+
+#define STM_REPORT_ID 0x10
+#define STM_REPORT_SERIAL 0x11
+
+struct dchid_stm_id {
+ u8 unk;
+ __le16 vendor_id;
+ __le16 product_id;
+ __le16 version_number;
+ u8 unk2;
+ u8 unk3;
+ u8 keyboard_type;
+ u8 serial_length;
+ /* Serial follows, but we grab it with a different report. */
+} __packed;
+
+struct dchid_work {
+ struct work_struct work;
+ struct dchid_iface *iface;
+
+ struct dchid_hdr hdr;
+ u8 data[];
+};
+
+struct dchid_iface {
+ struct dchid_dev *dchid;
+ struct hid_device *hid;
+ struct workqueue_struct *wq;
+
+ bool creating;
+ struct work_struct create_work;
+
+ int index;
+ const char *name;
+ struct fwnode_handle *fwnode;
+
+ u8 tx_seq;
+ bool deferred;
+ bool starting;
+ bool open;
+ struct completion ready;
+
+ void *hid_desc;
+ size_t hid_desc_len;
+
+ /* Lock for command submission state below */
+ spinlock_t out_lock;
+ u32 out_flags;
+ int out_report;
+ u32 retcode;
+ void *resp_buf;
+ size_t resp_size;
+ struct completion out_complete;
+};
+
+struct dchid_dev {
+ struct device *dev;
+ struct mbox_client dc_mbox_client;
+ struct mbox_chan *dc_mbox;
+
+ struct apple_rtkit *rtk;
+ void __iomem *asc_base;
+ void __iomem *sram_base;
+ struct resource sram_res;
+
+ bool id_ready;
+ struct dchid_stm_id device_id;
+ char serial[64];
+
+ u8 *rx_buf;
+ size_t rx_len;
+
+ struct dchid_iface *comm;
+ struct mutex ifaces_lock; /* protects ifaces array */
+ struct dchid_iface *ifaces[MAX_INTERFACES];
+
+ /* Workqueue to asynchronously create HID devices */
+ struct workqueue_struct *new_iface_wq;
+};
+
+static void dchid_destroy_wq(void *data)
+{
+ struct workqueue_struct *wq = data;
+
+ destroy_workqueue(wq);
+}
+
+static void dchid_fwnode_release(void *data)
+{
+ fwnode_handle_put(data);
+}
+
+static void dchid_free_mbox(void *data)
+{
+ mbox_free_channel(data);
+}
+
+static u32 dchid_checksum(const void *data, size_t len)
+{
+ const u8 *p = data;
+ u32 sum = 0;
+ int i;
+
+ while (len >= sizeof(u32)) {
+ sum += get_unaligned_le32(p);
+ p += sizeof(u32);
+ len -= sizeof(u32);
+ }
+
+ if (len) {
+ u32 tmp = 0;
+
+ for (i = 0; i < len; i++)
+ tmp |= p[i] << (i * 8);
+ sum += tmp;
+ }
+
+ return sum;
+}
+
+static struct dchid_iface *
+dchid_get_interface(struct dchid_dev *dchid, int index, const char *name)
+{
+ struct dchid_iface *iface;
+ struct fwnode_handle *fwnode;
+ int ret;
+
+ if (index >= MAX_INTERFACES) {
+ dev_err(dchid->dev, "interface index %d out of range\n", index);
+ return NULL;
+ }
+
+ mutex_lock(&dchid->ifaces_lock);
+ if (dchid->ifaces[index]) {
+ iface = dchid->ifaces[index];
+ mutex_unlock(&dchid->ifaces_lock);
+ return iface;
+ }
+
+ iface = devm_kzalloc(dchid->dev, sizeof(*iface), GFP_KERNEL);
+ if (!iface) {
+ mutex_unlock(&dchid->ifaces_lock);
+ return NULL;
+ }
+
+ iface->index = index;
+ iface->name = devm_kstrdup(dchid->dev, name, GFP_KERNEL);
+ if (!iface->name) {
+ mutex_unlock(&dchid->ifaces_lock);
+ return NULL;
+ }
+
+ iface->dchid = dchid;
+ iface->out_report = -1;
+ init_completion(&iface->out_complete);
+ init_completion(&iface->ready);
+ spin_lock_init(&iface->out_lock);
+
+ iface->wq = alloc_ordered_workqueue("dchid-%s", 0, iface->name);
+ if (!iface->wq) {
+ mutex_unlock(&dchid->ifaces_lock);
+ return NULL;
+ }
+
+ ret = devm_add_action_or_reset(dchid->dev, dchid_destroy_wq, iface->wq);
+ if (ret) {
+ mutex_unlock(&dchid->ifaces_lock);
+ return NULL;
+ }
+
+ if (!strcmp(name, "comm")) {
+ /* Comm is not a HID subdevice */
+ dchid->ifaces[index] = iface;
+ mutex_unlock(&dchid->ifaces_lock);
+ return iface;
+ }
+
+ fwnode = device_get_named_child_node(dchid->dev, name);
+ if (fwnode) {
+ iface->fwnode = fwnode;
+ ret = devm_add_action_or_reset(dchid->dev, dchid_fwnode_release,
+ iface->fwnode);
+ if (ret) {
+ mutex_unlock(&dchid->ifaces_lock);
+ return NULL;
+ }
+ } else {
+ iface->fwnode = dev_fwnode(dchid->dev);
+ }
+
+ dchid->ifaces[index] = iface;
+ mutex_unlock(&dchid->ifaces_lock);
+ return iface;
+}
+
+static int dchid_send(struct dchid_iface *iface, u32 flags, const void *msg,
+ size_t size)
+{
+ struct dchid_dev *dchid = iface->dchid;
+ size_t payload_padded = round_up(size, sizeof(u32));
+ size_t total_len = sizeof(struct dchid_hdr) + sizeof(struct dchid_subhdr) +
+ payload_padded + DCHID_CHECKSUM_LEN;
+ struct apple_dockchannel_msg dc_msg;
+ struct dchid_hdr *hdr;
+ struct dchid_subhdr *sub;
+ u32 *checksum_ptr;
+ u8 *buf;
+ int ret;
+
+ if (total_len > DCHID_RX_BUF_SIZE)
+ return -EINVAL;
+
+ buf = kzalloc(total_len, GFP_KERNEL);
+ if (!buf)
+ return -ENOMEM;
+
+ hdr = (struct dchid_hdr *)buf;
+ sub = (struct dchid_subhdr *)(buf + sizeof(*hdr));
+ checksum_ptr = (u32 *)(buf + total_len - DCHID_CHECKSUM_LEN);
+
+ hdr->hdr_len = sizeof(*hdr);
+ hdr->channel = DCHID_CHANNEL_CMD;
+ hdr->length = cpu_to_le16(payload_padded + sizeof(*sub));
+ hdr->seq = iface->tx_seq;
+ hdr->iface = iface->index;
+
+ sub->flags = (u8)flags;
+ sub->length = cpu_to_le16(size);
+
+ memcpy(buf + sizeof(*hdr) + sizeof(*sub), msg, size);
+
+ *checksum_ptr = 0xffffffff - dchid_checksum(buf, total_len - DCHID_CHECKSUM_LEN);
+
+ dc_msg.data = buf;
+ dc_msg.len = total_len;
+ ret = mbox_send_message(dchid->dc_mbox, &dc_msg);
+ kfree(buf);
+
+ return ret < 0 ? ret : 0;
+}
+
+static int dchid_cmd(struct dchid_iface *iface, u32 type, u32 req,
+ void *data, size_t size, void *resp_buf, size_t resp_size)
+{
+ unsigned long flags;
+ int ret;
+ int report_id;
+ bool timed_out = false;
+ u32 out_flags;
+
+ if (size < 1)
+ return -EINVAL;
+
+ report_id = *(u8 *)data;
+ out_flags = FIELD_PREP(FLAGS_GROUP, type) | FIELD_PREP(FLAGS_REQ, req);
+
+ spin_lock_irqsave(&iface->out_lock, flags);
+
+ /* Only one command can be in flight per interface */
+ if (WARN_ON(iface->out_report != -1)) {
+ spin_unlock_irqrestore(&iface->out_lock, flags);
+ return -EBUSY;
+ }
+
+ iface->out_report = report_id;
+ iface->out_flags = out_flags;
+ iface->retcode = 0;
+ iface->resp_buf = resp_buf;
+ iface->resp_size = resp_size;
+ reinit_completion(&iface->out_complete);
+
+ spin_unlock_irqrestore(&iface->out_lock, flags);
+
+ ret = dchid_send(iface, out_flags, data, size);
+ if (ret < 0) {
+ spin_lock_irqsave(&iface->out_lock, flags);
+ iface->out_report = -1;
+ iface->resp_buf = NULL;
+ iface->resp_size = 0;
+ spin_unlock_irqrestore(&iface->out_lock, flags);
+ return ret;
+ }
+
+ if (!wait_for_completion_timeout(&iface->out_complete,
+ msecs_to_jiffies(COMMAND_TIMEOUT_MS))) {
+ dev_err(iface->dchid->dev, "command 0x%x to iface %d (%s) timed out\n",
+ report_id, iface->index, iface->name);
+ timed_out = true;
+ }
+
+ spin_lock_irqsave(&iface->out_lock, flags);
+
+ if (timed_out && iface->out_report == report_id) {
+ ret = -ETIMEDOUT;
+ } else if (iface->retcode) {
+ dev_err(iface->dchid->dev,
+ "command 0x%x to iface %d (%s) failed with err 0x%x\n",
+ report_id, iface->index, iface->name, iface->retcode);
+ ret = -EIO;
+ } else {
+ ret = iface->resp_size;
+ }
+
+ iface->tx_seq++;
+ iface->out_report = -1;
+ iface->resp_buf = NULL;
+ iface->resp_size = 0;
+ spin_unlock_irqrestore(&iface->out_lock, flags);
+
+ return ret;
+}
+
+static int dchid_comm_cmd(struct dchid_dev *dchid, void *cmd, size_t size)
+{
+ return dchid_cmd(dchid->comm, HID_FEATURE_REPORT, REQ_SET_REPORT,
+ cmd, size, NULL, 0);
+}
+
+static int dchid_enable_interface(struct dchid_iface *iface)
+{
+ u8 cmd[] = { CMD_ENABLE_INTERFACE, iface->index };
+
+ return dchid_comm_cmd(iface->dchid, cmd, sizeof(cmd));
+}
+
+static int dchid_reset_interface(struct dchid_iface *iface, int state)
+{
+ u8 cmd[] = { CMD_RESET_INTERFACE, CMD_RESET_INTERFACE_SUB, iface->index,
+ (u8)state };
+
+ return dchid_comm_cmd(iface->dchid, cmd, sizeof(cmd));
+}
+
+static int dchid_start_interface(struct dchid_iface *iface)
+{
+ if (iface->starting)
+ return -EINPROGRESS;
+
+ dev_dbg(iface->dchid->dev, "starting interface %s\n", iface->name);
+
+ iface->starting = true;
+ dchid_reset_interface(iface, 0);
+ dchid_reset_interface(iface, 2);
+
+ return 0;
+}
+
+static int dchid_start(struct hid_device *hdev)
+{
+ return 0;
+}
+
+static int dchid_open(struct hid_device *hdev)
+{
+ struct dchid_iface *iface = hdev->driver_data;
+ int ret;
+
+ if (!completion_done(&iface->ready)) {
+ ret = dchid_start_interface(iface);
+ if (ret < 0)
+ return ret;
+
+ if (!wait_for_completion_timeout(&iface->ready,
+ msecs_to_jiffies(START_TIMEOUT_MS))) {
+ dev_err(iface->dchid->dev, "iface %s start timed out\n",
+ iface->name);
+ return -ETIMEDOUT;
+ }
+ }
+
+ iface->open = true;
+ return 0;
+}
+
+static void dchid_close(struct hid_device *hdev)
+{
+ struct dchid_iface *iface = hdev->driver_data;
+
+ iface->open = false;
+}
+
+static int dchid_parse(struct hid_device *hdev)
+{
+ struct dchid_iface *iface = hdev->driver_data;
+
+ return hid_parse_report(hdev, iface->hid_desc, iface->hid_desc_len);
+}
+
+/* Note: buf excludes report number. */
+static int dchid_get_report_cmd(struct dchid_iface *iface, u8 reportnum,
+ void *buf, size_t len)
+{
+ int ret;
+
+ ret = dchid_cmd(iface, HID_FEATURE_REPORT, REQ_GET_REPORT, &reportnum, 1,
+ buf, len);
+
+ return ret <= 0 ? ret : ret - 1;
+}
+
+/* Note: buf includes report number. */
+static int dchid_set_report(struct dchid_iface *iface, void *buf, size_t len)
+{
+ return dchid_cmd(iface, HID_OUTPUT_REPORT, REQ_SET_REPORT, buf, len,
+ NULL, 0);
+}
+
+static int dchid_raw_request(struct hid_device *hdev, unsigned char reportnum,
+ __u8 *buf, size_t len, unsigned char rtype,
+ int reqtype)
+{
+ struct dchid_iface *iface = hdev->driver_data;
+
+ switch (reqtype) {
+ case HID_REQ_GET_REPORT:
+ if (len < 1)
+ return -EINVAL;
+
+ buf[0] = reportnum;
+ return dchid_cmd(iface, rtype, REQ_GET_REPORT, &reportnum, 1,
+ buf + 1, len - 1);
+ case HID_REQ_SET_REPORT:
+ return dchid_set_report(iface, buf, len);
+ default:
+ return -EIO;
+ }
+}
+
+static const struct hid_ll_driver dchid_ll = {
+ .start = dchid_start,
+ .open = dchid_open,
+ .close = dchid_close,
+ .parse = dchid_parse,
+ .raw_request = dchid_raw_request,
+};
+
+static void dchid_create_interface_work(struct work_struct *ws)
+{
+ struct dchid_iface *iface = container_of(ws, struct dchid_iface, create_work);
+ struct dchid_dev *dchid = iface->dchid;
+ struct hid_device *hid;
+ char cap_name[16];
+ int ret;
+
+ if (iface->hid) {
+ dev_warn(dchid->dev, "interface %s already created\n", iface->name);
+ goto done;
+ }
+
+ ret = dchid_enable_interface(iface);
+ if (ret < 0) {
+ dev_warn(dchid->dev, "failed to enable %s: %d\n", iface->name, ret);
+ goto done;
+ }
+
+ iface->deferred = false;
+
+ hid = hid_allocate_device();
+ if (IS_ERR(hid))
+ goto done;
+
+ strscpy(cap_name, iface->name, sizeof(cap_name));
+ if (cap_name[0])
+ cap_name[0] = toupper(cap_name[0]);
+ snprintf(hid->name, sizeof(hid->name), "Apple DockChannel %s", cap_name);
+
+ snprintf(hid->phys, sizeof(hid->phys), "%s.%d", dev_name(dchid->dev),
+ iface->index);
+ strscpy(hid->uniq, dchid->serial, sizeof(hid->uniq));
+
+ hid->ll_driver = &dchid_ll;
+ hid->bus = BUS_HOST;
+ hid->vendor = le16_to_cpu(dchid->device_id.vendor_id);
+ hid->product = le16_to_cpu(dchid->device_id.product_id);
+ hid->version = le16_to_cpu(dchid->device_id.version_number);
+ hid->type = HID_TYPE_OTHER;
+ if (!strcmp(iface->name, "keyboard")) {
+ u32 country_code;
+
+ hid->group = HID_GROUP_APPLE_DOCKCHANNEL;
+
+ /*
+ * The device provides no reliable way to get the keyboard
+ * country code, so board devicetrees provide it instead,
+ * filled by the bootloader.
+ */
+ if (!fwnode_property_read_u32(iface->fwnode, "hid-country-code",
+ &country_code))
+ hid->country = country_code;
+ }
+
+ hid->dev.parent = iface->dchid->dev;
+ hid->driver_data = iface;
+ iface->hid = hid;
+
+ ret = hid_add_device(hid);
+ if (ret < 0) {
+ iface->hid = NULL;
+ hid_destroy_device(hid);
+ dev_warn(iface->dchid->dev, "failed to register HID device %s\n",
+ iface->name);
+ }
+
+done:
+ iface->creating = false;
+}
+
+static int dchid_create_interface(struct dchid_iface *iface)
+{
+ if (iface->creating)
+ return -EBUSY;
+
+ iface->creating = true;
+ INIT_WORK(&iface->create_work, dchid_create_interface_work);
+ return queue_work(iface->dchid->new_iface_wq, &iface->create_work);
+}
+
+static void dchid_handle_descriptor(struct dchid_iface *iface, void *hid_desc,
+ size_t desc_len)
+{
+ u8 *rdesc;
+ int i;
+
+ if (iface->hid)
+ return;
+
+ rdesc = devm_kmemdup(iface->dchid->dev, hid_desc, desc_len,
+ GFP_KERNEL);
+ if (!rdesc)
+ return;
+
+ /* Fix up oversized report sizes in DockChannel report descriptors */
+ if (desc_len >= 5) {
+ for (i = 0; i <= (int)desc_len - 5; i++) {
+ if (rdesc[i] == 0x76 && rdesc[i + 1] == 0x00 &&
+ rdesc[i + 2] == 0x40 && rdesc[i + 3] == 0x95) {
+ u8 count = rdesc[i + 4];
+
+ if (count > 0 && count < 32) {
+ dev_info(iface->dchid->dev,
+ "fixing up interface %s (%d) report size\n",
+ iface->name, iface->index);
+ rdesc[i] = 0x75;
+ rdesc[i + 1] = 0x08;
+ rdesc[i + 2] = 0x96;
+ rdesc[i + 3] = 0x00;
+ rdesc[i + 4] = count * 8;
+ }
+ }
+ }
+ }
+
+ iface->hid_desc = rdesc;
+ iface->hid_desc_len = desc_len;
+}
+
+static void dchid_handle_ready(struct dchid_dev *dchid, void *data, size_t length)
+{
+ struct dchid_iface *iface;
+ u8 *pkt = data;
+ u8 index;
+ int i;
+ int ret;
+
+ if (length < 2)
+ return;
+
+ index = pkt[1];
+ if (index >= MAX_INTERFACES)
+ return;
+
+ iface = dchid->ifaces[index];
+ if (!iface)
+ return;
+
+ dev_dbg(dchid->dev, "interface %s is now ready\n", iface->name);
+ complete_all(&iface->ready);
+
+ /* When STM is ready, grab global device info */
+ if (!strcmp(iface->name, "stm")) {
+ ret = dchid_get_report_cmd(iface, STM_REPORT_ID, &dchid->device_id,
+ sizeof(dchid->device_id));
+ if (ret < (int)sizeof(dchid->device_id)) {
+ dev_warn(iface->dchid->dev, "failed to get device ID from STM\n");
+ /* Fake it and keep going. Things might still work. */
+ memset(&dchid->device_id, 0, sizeof(dchid->device_id));
+ }
+
+ ret = dchid_get_report_cmd(iface, STM_REPORT_SERIAL, dchid->serial,
+ sizeof(dchid->serial) - 1);
+ if (ret < 0) {
+ dev_warn(iface->dchid->dev, "failed to get serial from STM\n");
+ dchid->serial[0] = 0;
+ }
+
+ dchid->id_ready = true;
+ for (i = 0; i < MAX_INTERFACES; i++) {
+ if (!dchid->ifaces[i] || !dchid->ifaces[i]->deferred)
+ continue;
+ dchid_create_interface(dchid->ifaces[i]);
+ }
+ }
+}
+
+static void dchid_handle_init(struct dchid_dev *dchid, void *data, size_t length)
+{
+ struct dchid_init_hdr *hdr = data;
+ struct dchid_init_block_hdr *blk;
+ struct dchid_iface *iface;
+ u8 *p = data;
+
+ if (length < sizeof(*hdr))
+ return;
+
+ iface = dchid_get_interface(dchid, hdr->iface, hdr->name);
+ if (!iface)
+ return;
+
+ p += sizeof(*hdr);
+ length -= sizeof(*hdr);
+
+ while (length >= sizeof(*blk)) {
+ u16 blk_len;
+
+ blk = (struct dchid_init_block_hdr *)p;
+ p += sizeof(*blk);
+ length -= sizeof(*blk);
+
+ blk_len = le16_to_cpu(blk->length);
+ if (blk_len > length)
+ break;
+
+ switch (le16_to_cpu(blk->type)) {
+ case INIT_HID_DESCRIPTOR:
+ dchid_handle_descriptor(iface, p, blk_len);
+ break;
+ case INIT_PRODUCT_NAME:
+ if (blk_len > 0 && p[blk_len - 1] != 0)
+ dev_warn(dchid->dev, "unterminated product name for %s\n",
+ iface->name);
+ break;
+ }
+
+ p += blk_len;
+ length -= blk_len;
+
+ if (le16_to_cpu(blk->type) == INIT_TERMINATOR)
+ break;
+ }
+
+ if (hdr->more_packets)
+ return;
+
+ /*
+ * Prefer to enable STM first, since it provides device IDs. Some
+ * firmware versions do not expose STM, so let the keyboard start
+ * without it.
+ */
+ if (iface->dchid->id_ready || !strcmp(iface->name, "stm") ||
+ !strcmp(iface->name, "keyboard"))
I specifically asked for a mechanism to let the keyboard probe even on devices which do not expose/have stm. Thanks for adding that!
However, I think this might need some more sophisticated mechanism to decide whether the stm is still going to appear after the keyboard, or not at all. I'm not sure if there is a way to tell this at this point, or we need to add a timeout for the stm to appearing, which needs to expire before we create the other interfaces with fake serials.
+ dchid_create_interface(iface);
+ else
+ iface->deferred = true;
+}
+
+static void dchid_handle_event(struct dchid_dev *dchid, void *data, size_t length)
+{
+ u8 *p = data;
+
+ if (!length)
+ return;
+
+ switch (*p) {
+ case EVENT_INIT:
+ dchid_handle_init(dchid, data, length);
+ break;
+ case EVENT_READY:
+ dchid_handle_ready(dchid, data, length);
+ break;
+ }
+}
+
+static void dchid_handle_report(struct dchid_iface *iface, void *data, size_t length)
+{
+ if (!iface->hid || !iface->open)
+ return;
+
+ hid_input_report(iface->hid, HID_INPUT_REPORT, data, length, 1);
+}
+
+static void dchid_packet_work(struct work_struct *ws)
+{
+ struct dchid_work *work = container_of(ws, struct dchid_work, work);
+ struct dchid_subhdr *shdr = (void *)work->data;
+ struct dchid_dev *dchid = work->iface->dchid;
+ u16 hdr_len = le16_to_cpu(work->hdr.length);
+ u16 sub_len;
+ int type;
+ u8 *payload;
+
+ if (hdr_len < sizeof(*shdr)) {
+ dev_err(dchid->dev, "bad subheader length\n");
+ goto done;
+ }
+
+ sub_len = le16_to_cpu(shdr->length);
+ if (sub_len > hdr_len - sizeof(*shdr)) {
+ dev_err(dchid->dev, "bad subheader length\n");
+ goto done;
+ }
+
+ type = FIELD_GET(FLAGS_GROUP, shdr->flags);
+ payload = work->data + sizeof(*shdr);
+
+ switch (type) {
+ case HID_INPUT_REPORT:
+ if (work->hdr.iface == IFACE_COMM)
+ dchid_handle_event(dchid, payload, sub_len);
+ else
+ dchid_handle_report(work->iface, payload, sub_len);
+ break;
+ }
+
+done:
+ kfree(work);
+}
+
+static void dchid_handle_ack(struct dchid_iface *iface, struct dchid_hdr *hdr,
+ void *data)
+{
+ struct dchid_subhdr *shdr = data;
+ u8 *payload = data + sizeof(*shdr);
+ u16 hdr_len = le16_to_cpu(hdr->length);
+ u16 sub_len = le16_to_cpu(shdr->length);
+ unsigned long flags;
+ bool complete_cmd = false;
+
+ if (hdr_len < sizeof(*shdr) || sub_len > hdr_len - sizeof(*shdr) ||
+ sub_len < 1)
+ return;
+
+ spin_lock_irqsave(&iface->out_lock, flags);
+
+ if (shdr->flags == iface->out_flags && iface->tx_seq == hdr->seq &&
+ iface->out_report == payload[0]) {
+ if (iface->resp_buf && iface->resp_size)
+ memcpy(iface->resp_buf, payload + 1,
+ min_t(size_t, sub_len - 1, iface->resp_size));
+
+ iface->resp_size = sub_len;
+ iface->out_report = -1;
+ iface->retcode = le32_to_cpu(shdr->retcode);
+ complete_cmd = true;
+ }
+
+ spin_unlock_irqrestore(&iface->out_lock, flags);
+
+ if (complete_cmd)
+ complete(&iface->out_complete);
+}
+
+static void dchid_process_packet(struct dchid_dev *dchid, struct dchid_hdr *hdr,
+ u8 *payload, size_t payload_len, u8 *packet,
+ size_t packet_len)
+{
+ struct dchid_work *work;
+
+ if (dchid_checksum(packet, packet_len) != DCHID_CHECKSUM_SEED) {
+ dev_err_ratelimited(dchid->dev, "checksum error\n");
+ return;
+ }
+
+ if (payload_len < sizeof(struct dchid_subhdr))
+ return;
+
+ if (hdr->iface >= MAX_INTERFACES || !dchid->ifaces[hdr->iface])
+ return;
+
+ if (hdr->channel == DCHID_CHANNEL_CMD) {
+ dchid_handle_ack(dchid->ifaces[hdr->iface], hdr, payload);
+ return;
+ }
+
+ if (hdr->channel != DCHID_CHANNEL_REPORT)
+ return;
+
+ work = kzalloc(sizeof(*work) + payload_len, GFP_ATOMIC);
+ if (!work)
+ return;
+
+ work->hdr = *hdr;
+ work->iface = dchid->ifaces[hdr->iface];
+ memcpy(work->data, payload, payload_len);
+ INIT_WORK(&work->work, dchid_packet_work);
+
+ queue_work(work->iface->wq, &work->work);
+}
+
+static void dchid_consume_rx(struct dchid_dev *dchid)
+{
+ while (dchid->rx_len >= sizeof(struct dchid_hdr)) {
+ struct dchid_hdr *hdr = (struct dchid_hdr *)dchid->rx_buf;
+ size_t payload_len;
+ size_t packet_len;
+
+ if (hdr->hdr_len != sizeof(*hdr)) {
+ dev_err_ratelimited(dchid->dev, "bad header length %u\n",
+ hdr->hdr_len);
+ dchid->rx_len = 0;
+ return;
+ }
+
+ payload_len = le16_to_cpu(hdr->length);
+ packet_len = sizeof(*hdr) + payload_len + DCHID_CHECKSUM_LEN;
+ if (packet_len > DCHID_RX_BUF_SIZE) {
+ dev_err_ratelimited(dchid->dev, "oversized packet %zu\n",
+ packet_len);
+ dchid->rx_len = 0;
+ return;
+ }
+
+ if (dchid->rx_len < packet_len)
+ return;
+
+ dchid_process_packet(dchid, hdr, dchid->rx_buf + sizeof(*hdr),
+ payload_len, dchid->rx_buf, packet_len);
+
+ dchid->rx_len -= packet_len;
+ memmove(dchid->rx_buf, dchid->rx_buf + packet_len, dchid->rx_len);
+ }
+}
+
+static void dchid_rx_callback(struct mbox_client *cl, void *mssg)
+{
+ struct dchid_dev *dchid = container_of(cl, struct dchid_dev, dc_mbox_client);
+ struct apple_dockchannel_msg *msg = mssg;
+
+ if (!msg || !msg->data || !msg->len)
+ return;
+
+ if (msg->len > DCHID_RX_BUF_SIZE - dchid->rx_len) {
+ dev_err_ratelimited(dchid->dev, "RX buffer overflow\n");
+ dchid->rx_len = 0;
+ return;
+ }
+
+ memcpy(dchid->rx_buf + dchid->rx_len, msg->data, msg->len);
+ dchid->rx_len += msg->len;
+
+ dchid_consume_rx(dchid);
+}
+
+static int dchid_rtkit_shmem_setup(void *cookie, struct apple_rtkit_shmem *bfr)
+{
+ struct dchid_dev *dchid = cookie;
+ struct resource res = {
+ .start = bfr->iova,
+ .end = bfr->iova + bfr->size - 1,
+ .name = "rtkit_map",
+ };
+
+ if (!bfr->iova) {
+ bfr->buffer = dma_alloc_coherent(dchid->dev, bfr->size,
+ &bfr->iova, GFP_KERNEL);
+ if (!bfr->buffer)
+ return -ENOMEM;
+ return 0;
+ }
+
+ if (!dchid->sram_res.start)
+ return -EFAULT;
+
+ res.flags = dchid->sram_res.flags;
+ if (res.end < res.start || !resource_contains(&dchid->sram_res, &res))
+ return -EFAULT;
+
+ bfr->iomem = dchid->sram_base + (res.start - dchid->sram_res.start);
+ bfr->is_mapped = true;
+
+ return 0;
+}
+
+static void dchid_rtkit_shmem_destroy(void *cookie, struct apple_rtkit_shmem *bfr)
+{
+ struct dchid_dev *dchid = cookie;
+
+ if (bfr->buffer)
+ dma_free_coherent(dchid->dev, bfr->size, bfr->buffer, bfr->iova);
+}
+
+static const struct apple_rtkit_ops dchid_rtkit_ops = {
+ .shmem_setup = dchid_rtkit_shmem_setup,
+ .shmem_destroy = dchid_rtkit_shmem_destroy,
+};
+
+static int dchid_map_helper_cpu(struct platform_device *pdev, struct dchid_dev *dchid)
+{
+ struct resource *res;
+
+ dchid->asc_base = devm_platform_ioremap_resource_byname(pdev, "coproc-asc");
+ if (IS_ERR(dchid->asc_base))
+ return PTR_ERR(dchid->asc_base);
+
+ res = platform_get_resource_byname(pdev, IORESOURCE_MEM, "coproc-sram");
+ if (!res)
+ return -EINVAL;
+
+ dchid->sram_res = *res;
+
+ dchid->sram_base = devm_ioremap_resource(&pdev->dev, res);
+ if (IS_ERR(dchid->sram_base))
+ return PTR_ERR(dchid->sram_base);
+
+ return 0;
+}
+
+static int dchid_probe(struct platform_device *pdev)
+{
+ struct device *dev = &pdev->dev;
+ struct dchid_dev *dchid;
+ int ret;
+
+ ret = dma_set_mask_and_coherent(dev, DMA_BIT_MASK(44));
+ if (ret)
+ return dev_err_probe(dev, ret, "failed to set DMA mask\n");
+
+ dchid = devm_kzalloc(dev, sizeof(*dchid), GFP_KERNEL);
+ if (!dchid)
+ return -ENOMEM;
+
+ dchid->rx_buf = devm_kmalloc(dev, DCHID_RX_BUF_SIZE, GFP_KERNEL);
+ if (!dchid->rx_buf)
+ return -ENOMEM;
+
+ dchid->dev = dev;
+ mutex_init(&dchid->ifaces_lock);
+ platform_set_drvdata(pdev, dchid);
+
+ ret = dchid_map_helper_cpu(pdev, dchid);
+ if (ret)
+ return dev_err_probe(dev, ret, "failed to map helper CPU\n");
+
+ dchid->dc_mbox_client.dev = dev;
+ dchid->dc_mbox_client.tx_block = true;
+ dchid->dc_mbox_client.rx_callback = dchid_rx_callback;
+
+ dchid->dc_mbox = mbox_request_channel_byname(&dchid->dc_mbox_client,
+ "dockchannel");
+ if (IS_ERR(dchid->dc_mbox))
+ return dev_err_probe(dev, PTR_ERR(dchid->dc_mbox),
+ "failed to request DockChannel mailbox\n");
+
+ ret = devm_add_action_or_reset(dev, dchid_free_mbox, dchid->dc_mbox);
+ if (ret)
+ return ret;
+
+ dchid->rtk = devm_apple_rtkit_init(dev, dchid, "asc", 0, &dchid_rtkit_ops);
+ if (IS_ERR(dchid->rtk))
+ return dev_err_probe(dev, PTR_ERR(dchid->rtk), "failed to init RTKit\n");
+
+ writel_relaxed(APPLE_ASC_CPU_CONTROL_RUN,
+ dchid->asc_base + APPLE_ASC_CPU_CONTROL);
+
+ ret = apple_rtkit_wake(dchid->rtk);
+ if (ret)
+ return dev_err_probe(dev, ret, "failed to wake coprocessor\n");
+
+ dchid->new_iface_wq = alloc_ordered_workqueue("dchid-new", 0);
+ if (!dchid->new_iface_wq)
+ return dev_err_probe(dev, -ENOMEM, "failed to allocate workqueue\n");
+
+ ret = devm_add_action_or_reset(dev, dchid_destroy_wq, dchid->new_iface_wq);
+ if (ret)
+ return ret;
+
+ dchid->comm = dchid_get_interface(dchid, IFACE_COMM, "comm");
+ if (!dchid->comm)
+ return dev_err_probe(dev, -EIO, "failed to init comm interface\n");
+
+ return 0;
+}
+
+static void dchid_remove(struct platform_device *pdev)
+{
+ struct dchid_dev *dchid = platform_get_drvdata(pdev);
+ int i;
+
+ if (dchid->dc_mbox) {
+ devm_release_action(&pdev->dev, dchid_free_mbox, dchid->dc_mbox);
+ dchid->dc_mbox = NULL;
+ }
+
+ if (dchid->rtk && apple_rtkit_is_running(dchid->rtk))
+ apple_rtkit_quiesce(dchid->rtk);
+
+ if (dchid->asc_base)
+ writel_relaxed(0, dchid->asc_base + APPLE_ASC_CPU_CONTROL);
+
+ for (i = 0; i < MAX_INTERFACES; i++) {
+ struct dchid_iface *iface = dchid->ifaces[i];
+
+ if (!iface)
+ continue;
+
+ cancel_work_sync(&iface->create_work);
+ flush_workqueue(iface->wq);
+
+ if (iface->hid)
+ hid_destroy_device(iface->hid);
+ }
+
+ if (dchid->new_iface_wq)
+ flush_workqueue(dchid->new_iface_wq);
+}
+
+static const struct of_device_id dchid_of_match[] = {
+ { .compatible = "apple,t8122-dockchannel-hid" },
+ { .compatible = "apple,t8112-dockchannel-hid" },
+ {},
+};
+MODULE_DEVICE_TABLE(of, dchid_of_match);
+
+static struct platform_driver dchid_platform_driver = {
+ .driver = {
+ .name = "dockchannel-hid",
+ .of_match_table = dchid_of_match,
+ },
+ .probe = dchid_probe,
+ .remove = dchid_remove,
+};
+module_platform_driver(dchid_platform_driver);
+
+MODULE_DESCRIPTION("Apple DockChannel HID transport driver");
+MODULE_AUTHOR("Hector Martin <marcan@xxxxxxxxx>");
+MODULE_AUTHOR("Michael Reeves <michael.reeves077@xxxxxxxxx>");
+MODULE_LICENSE("Dual MIT/GPL");