[PATCH RESEND v6 2/4] input: apple_z2: Add a driver for Apple Z2 touchscreens

Sasha Finkelstein via B4 Relay
2025-02-17T11:38:16Z

From: Sasha Finkelstein <fnkl.kernel@gmail.com>

Adds a driver for Apple touchscreens using the Z2 protocol.

Signed-off-by: Janne Grunau <j@jannau.net>
Reviewed-by: Neal Gompa <neal@gompa.dev>
Signed-off-by: Sasha Finkelstein <fnkl.kernel@gmail.com>
---
drivers/input/touchscreen/Kconfig | 13 +
drivers/input/touchscreen/Makefile | 1 +
drivers/input/touchscreen/apple_z2.c | 473 +++++++++++++++++++++++++++++++++++
3 files changed, 487 insertions(+)

diff --git a/drivers/input/touchscreen/Kconfig b/drivers/input/touchscreen/Kconfig
index 1a03de7fcfa66c0f60768be17d776a79e36e570e..6c885cc58f323b3628538d41460248f8ab1dbf7d 100644
--- a/drivers/input/touchscreen/Kconfig
+++ b/drivers/input/touchscreen/Kconfig
@@ -103,6 +103,19 @@ config TOUCHSCREEN_ADC
To compile this driver as a module, choose M here: the
module will be called resistive-adc-touch.ko.

+config TOUCHSCREEN_APPLE_Z2
+ tristate "Apple Z2 touchscreens"
+ default ARCH_APPLE
+ depends on SPI
+ help
+ Say Y here if you have an Apple device with
+ a touchscreen or a touchbar.
+
+ If unsure, say N.
+
+ To compile this driver as a module, choose M here: the
+ module will be called apple_z2.
+
config TOUCHSCREEN_AR1021_I2C
tristate "Microchip AR1020/1021 i2c touchscreen"
depends on I2C && OF
diff --git a/drivers/input/touchscreen/Makefile b/drivers/input/touchscreen/Makefile
index 82bc837ca01e2ee18c5e9c578765d55ef9fab6d4..97a025c6a3770fb80255246eb63c11688ebd79eb 100644
--- a/drivers/input/touchscreen/Makefile
+++ b/drivers/input/touchscreen/Makefile
@@ -15,6 +15,7 @@ obj-$(CONFIG_TOUCHSCREEN_AD7879_I2C) += ad7879-i2c.o
obj-$(CONFIG_TOUCHSCREEN_AD7879_SPI) += ad7879-spi.o
obj-$(CONFIG_TOUCHSCREEN_ADC) += resistive-adc-touch.o
obj-$(CONFIG_TOUCHSCREEN_ADS7846) += ads7846.o
+obj-$(CONFIG_TOUCHSCREEN_APPLE_Z2) += apple_z2.o
obj-$(CONFIG_TOUCHSCREEN_AR1021_I2C) += ar1021_i2c.o
obj-$(CONFIG_TOUCHSCREEN_ATMEL_MXT) += atmel_mxt_ts.o
obj-$(CONFIG_TOUCHSCREEN_AUO_PIXCIR) += auo-pixcir-ts.o
diff --git a/drivers/input/touchscreen/apple_z2.c b/drivers/input/touchscreen/apple_z2.c
new file mode 100644
index 0000000000000000000000000000000000000000..a996cf28e4d25fd747bdc6be7ff64a40238641a4
--- /dev/null
+++ b/drivers/input/touchscreen/apple_z2.c
@@ -0,0 +1,473 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Apple Z2 touchscreen driver
+ *
+ * Copyright (C) The Asahi Linux Contributors
+ */
+
+#include <linux/delay.h>
+#include <linux/firmware.h>
+#include <linux/input.h>
+#include <linux/input/mt.h>
+#include <linux/input/touchscreen.h>
+#include <linux/interrupt.h>
+#include <linux/module.h>
+#include <linux/of.h>
+#include <linux/spi/spi.h>
+#include <linux/unaligned.h>
+
+#define APPLE_Z2_NUM_FINGERS_OFFSET 16
+#define APPLE_Z2_FINGERS_OFFSET 24
+#define APPLE_Z2_TOUCH_STARTED 3
+#define APPLE_Z2_TOUCH_MOVED 4
+#define APPLE_Z2_CMD_READ_INTERRUPT_DATA 0xEB
+#define APPLE_Z2_HBPP_CMD_BLOB 0x3001
+#define APPLE_Z2_FW_MAGIC 0x5746325A
+#define LOAD_COMMAND_INIT_PAYLOAD 0
+#define LOAD_COMMAND_SEND_BLOB 1
+#define LOAD_COMMAND_SEND_CALIBRATION 2
+#define CAL_PROP_NAME "apple,z2-cal-blob"
+
+struct apple_z2 {
+ struct spi_device *spidev;
+ struct gpio_desc *reset_gpio;
+ struct input_dev *input_dev;
+ struct completion boot_irq;
+ bool booted;
+ int index_parity;
+ struct touchscreen_properties props;
+ const char *fw_name;
+ u8 *tx_buf;
+ u8 *rx_buf;
+};
+
+struct apple_z2_finger {
+ u8 finger;
+ u8 state;
+ __le16 unknown2;
+ __le16 abs_x;
+ __le16 abs_y;
+ __le16 rel_x;
+ __le16 rel_y;
+ __le16 tool_major;
+ __le16 tool_minor;
+ __le16 orientation;
+ __le16 touch_major;
+ __le16 touch_minor;
+ __le16 unused[2];
+ __le16 pressure;
+ __le16 multi;
+} __packed;
+
+struct apple_z2_hbpp_blob_hdr {
+ __le16 cmd;
+ __le16 len;
+ __le32 addr;
+ __le16 checksum;
+};
+
+struct apple_z2_fw_hdr {
+ __le32 magic;
+ __le32 version;
+};
+
+struct apple_z2_read_interrupt_cmd {
+ u8 cmd;
+ u8 counter;
+ u8 unused[12];
+ __le16 checksum;
+};
+
+static void apple_z2_parse_touches(struct apple_z2 *z2,
+ const u8 *msg, size_t msg_len)
+{
+ int i;
+ int nfingers;
+ int slot;
+ int slot_valid;
+ struct apple_z2_finger *fingers;
+
+ if (msg_len <= APPLE_Z2_NUM_FINGERS_OFFSET)
+ return;
+ nfingers = msg[APPLE_Z2_NUM_FINGERS_OFFSET];
+ fingers = (struct apple_z2_finger *)(msg + APPLE_Z2_FINGERS_OFFSET);
+ for (i = 0; i < nfingers; i++) {
+ slot = input_mt_get_slot_by_key(z2->input_dev, fingers[i].finger);
+ if (slot < 0) {
+ dev_warn(&z2->spidev->dev, "unable to get slot for finger\n");
+ continue;
+ }
+ slot_valid = fingers[i].state == APPLE_Z2_TOUCH_STARTED ||
+ fingers[i].state == APPLE_Z2_TOUCH_MOVED;
+ input_mt_slot(z2->input_dev, slot);
+ if (!input_mt_report_slot_state(z2->input_dev, MT_TOOL_FINGER, slot_valid))
+ continue;
+ touchscreen_report_pos(z2->input_dev, &z2->props,
+ le16_to_cpu(fingers[i].abs_x),
+ le16_to_cpu(fingers[i].abs_y),
+ true);
+ input_report_abs(z2->input_dev, ABS_MT_WIDTH_MAJOR,
+ le16_to_cpu(fingers[i].tool_major));
+ input_report_abs(z2->input_dev, ABS_MT_WIDTH_MINOR,
+ le16_to_cpu(fingers[i].tool_minor));
+ input_report_abs(z2->input_dev, ABS_MT_ORIENTATION,
+ le16_to_cpu(fingers[i].orientation));
+ input_report_abs(z2->input_dev, ABS_MT_TOUCH_MAJOR,
+ le16_to_cpu(fingers[i].touch_major));
+ input_report_abs(z2->input_dev, ABS_MT_TOUCH_MINOR,
+ le16_to_cpu(fingers[i].touch_minor));
+ }
+ input_mt_sync_frame(z2->input_dev);
+ input_sync(z2->input_dev);
+}
+
+static int apple_z2_read_packet(struct apple_z2 *z2)
+{
+ struct apple_z2_read_interrupt_cmd *len_cmd = (void *)z2->tx_buf;
+ struct spi_transfer xfer;
+ int error;
+ size_t pkt_len;
+
+ memset(&xfer, 0, sizeof(xfer));
+ len_cmd->cmd = APPLE_Z2_CMD_READ_INTERRUPT_DATA;
+ len_cmd->counter = z2->index_parity + 1;
+ len_cmd->checksum =
+ cpu_to_le16(APPLE_Z2_CMD_READ_INTERRUPT_DATA + len_cmd->counter);
+ z2->index_parity = !z2->index_parity;
+ xfer.tx_buf = z2->tx_buf;
+ xfer.rx_buf = z2->rx_buf;
+ xfer.len = sizeof(*len_cmd);
+
+ error = spi_sync_transfer(z2->spidev, &xfer, 1);
+ if (error)
+ return error;
+
+ pkt_len = (get_unaligned_le16(z2->rx_buf + 1) + 8) & 0xfffffffc;
+
+ error = spi_read(z2->spidev, z2->rx_buf, pkt_len);
+ if (error)
+ return error;
+
+ apple_z2_parse_touches(z2, z2->rx_buf + 5, pkt_len - 5);
+
+ return 0;
+}
+
+static irqreturn_t apple_z2_irq(int irq, void *data)
+{
+ struct apple_z2 *z2 = data;
+
+ if (unlikely(!z2->booted))
+ complete(&z2->boot_irq);
+ else
+ apple_z2_read_packet(z2);
+
+ return IRQ_HANDLED;
+}
+
+/* Build calibration blob, caller is responsible for freeing the blob data. */
+static const u8 *apple_z2_build_cal_blob(struct apple_z2 *z2,
+ u32 address, size_t *size)
+{
+ u8 *cal_data;
+ int cal_size;
+ size_t blob_size;
+ u32 checksum;
+ u16 checksum_hdr;
+ int i;
+ struct apple_z2_hbpp_blob_hdr *hdr;
+ int error;
+
+ if (!device_property_present(&z2->spidev->dev, CAL_PROP_NAME))
+ return NULL;
+
+ cal_size = device_property_count_u8(&z2->spidev->dev, CAL_PROP_NAME);
+ if (cal_size < 0)
+ return ERR_PTR(cal_size);
+
+ blob_size = sizeof(struct apple_z2_hbpp_blob_hdr) + cal_size + sizeof(__le32);
+ u8 *blob_data __free(kfree) = kzalloc(blob_size, GFP_KERNEL);
+ if (!blob_data)
+ return ERR_PTR(-ENOMEM);
+
+ hdr = (struct apple_z2_hbpp_blob_hdr *)blob_data;
+ hdr->cmd = cpu_to_le16(APPLE_Z2_HBPP_CMD_BLOB);
+ hdr->len = cpu_to_le16(round_up(cal_size, 4) / 4);
+ hdr->addr = cpu_to_le32(address);
+
+ checksum_hdr = 0;
+ for (i = 2; i < 8; i++)
+ checksum_hdr += blob_data[i];
+ hdr->checksum = cpu_to_le16(checksum_hdr);
+
+ cal_data = blob_data + sizeof(struct apple_z2_hbpp_blob_hdr);
+ error = device_property_read_u8_array(&z2->spidev->dev, CAL_PROP_NAME,
+ cal_data, cal_size);
+ if (error)
+ return ERR_PTR(error);
+
+ checksum = 0;
+ for (i = 0; i < cal_size; i++)
+ checksum += cal_data[i];
+ put_unaligned_le32(checksum, cal_data + cal_size);
+
+ *size = blob_size;
+ return no_free_ptr(blob_data);
+}
+
+static int apple_z2_send_firmware_blob(struct apple_z2 *z2, const u8 *data,
+ u32 size, bool init)
+{
+ struct spi_message msg;
+ struct spi_transfer blob_xfer, ack_xfer;
+ int error;
+
+ z2->tx_buf[0] = 0x1a;
+ z2->tx_buf[1] = 0xa1;
+
+ spi_message_init(&msg);
+ memset(&blob_xfer, 0, sizeof(blob_xfer));
+ memset(&ack_xfer, 0, sizeof(ack_xfer));
+
+ blob_xfer.tx_buf = data;
+ blob_xfer.len = size;
+ blob_xfer.bits_per_word = init ? 8 : 16;
+ spi_message_add_tail(&blob_xfer, &msg);
+
+ ack_xfer.tx_buf = z2->tx_buf;
+ ack_xfer.len = 2;
+ spi_message_add_tail(&ack_xfer, &msg);
+
+ reinit_completion(&z2->boot_irq);
+ error = spi_sync(z2->spidev, &msg);
+ if (error)
+ return error;
+
+ /* Irq only happens sometimes, but the thing boots reliably nonetheless */
+ wait_for_completion_timeout(&z2->boot_irq, msecs_to_jiffies(20));
+
+ return 0;
+}
+
+static int apple_z2_upload_firmware(struct apple_z2 *z2)
+{
+ const struct apple_z2_fw_hdr *fw_hdr;
+ size_t fw_idx = sizeof(struct apple_z2_fw_hdr);
+ int error;
+ u32 load_cmd;
+ u32 address;
+ bool init;
+ size_t size;
+
+ const struct firmware *fw __free(firmware) = NULL;
+ error = request_firmware(&fw, z2->fw_name, &z2->spidev->dev);
+ if (error) {
+ dev_err(&z2->spidev->dev, "unable to load firmware\n");
+ return error;
+ }
+
+ fw_hdr = (const struct apple_z2_fw_hdr *)fw->data;
+ if (le32_to_cpu(fw_hdr->magic) != APPLE_Z2_FW_MAGIC || le32_to_cpu(fw_hdr->version) != 1) {
+ dev_err(&z2->spidev->dev, "invalid firmware header\n");
+ return -EINVAL;
+ }
+
+ /*
+ * This will interrupt the upload half-way if the file is malformed
+ * As the device has no non-volatile storage to corrupt, and gets reset
+ * on boot anyway, this is fine.
+ */
+ while (fw_idx < fw->size) {
+ if (fw->size - fw_idx < 8) {
+ dev_err(&z2->spidev->dev, "firmware malformed\n");
+ return -EINVAL;
+ }
+
+ load_cmd = le32_to_cpup((__force __le32 *)(fw->data + fw_idx));
+ fw_idx += sizeof(u32);
+ if (load_cmd == LOAD_COMMAND_INIT_PAYLOAD || load_cmd == LOAD_COMMAND_SEND_BLOB) {
+ size = le32_to_cpup((__force __le32 *)(fw->data + fw_idx));
+ fw_idx += sizeof(u32);
+ if (fw->size - fw_idx < size) {
+ dev_err(&z2->spidev->dev, "firmware malformed\n");
+ return -EINVAL;
+ }
+ init = load_cmd == LOAD_COMMAND_INIT_PAYLOAD;
+ error = apple_z2_send_firmware_blob(z2, fw->data + fw_idx,
+ size, init);
+ if (error)
+ return error;
+ fw_idx += size;
+ } else if (load_cmd == LOAD_COMMAND_SEND_CALIBRATION) {
+ address = le32_to_cpup((__force __le32 *)(fw->data + fw_idx));
+ fw_idx += sizeof(u32);
+
+ const u8 *data __free(kfree) =
+ apple_z2_build_cal_blob(z2, address, &size);
+ if (IS_ERR(data))
+ return PTR_ERR(data);
+
+ if (data) {
+ error = apple_z2_send_firmware_blob(z2, data, size, false);
+ if (error)
+ return error;
+ }
+ } else {
+ dev_err(&z2->spidev->dev, "firmware malformed\n");
+ return -EINVAL;
+ }
+ fw_idx = round_up(fw_idx, 4);
+ }
+
+
+ z2->booted = true;
+ apple_z2_read_packet(z2);
+ return 0;
+}
+
+static int apple_z2_boot(struct apple_z2 *z2)
+{
+ int error;
+
+ reinit_completion(&z2->boot_irq);
+ enable_irq(z2->spidev->irq);
+ gpiod_set_value(z2->reset_gpio, 0);
+ if (!wait_for_completion_timeout(&z2->boot_irq, msecs_to_jiffies(20)))
+ return -ETIMEDOUT;
+
+ error = apple_z2_upload_firmware(z2);
+ if (error) {
+ gpiod_set_value(z2->reset_gpio, 1);
+ disable_irq(z2->spidev->irq);
+ return error;
+ }
+ return 0;
+}
+
+static int apple_z2_probe(struct spi_device *spi)
+{
+ struct device *dev = &spi->dev;
+ struct apple_z2 *z2;
+ int error;
+
+ z2 = devm_kzalloc(dev, sizeof(*z2), GFP_KERNEL);
+ if (!z2)
+ return -ENOMEM;
+
+ z2->tx_buf = devm_kzalloc(dev, sizeof(struct apple_z2_read_interrupt_cmd), GFP_KERNEL);
+ if (!z2->tx_buf)
+ return -ENOMEM;
+ /* 4096 will end up being rounded up to 8192 due to devres header */
+ z2->rx_buf = devm_kzalloc(dev, 4000, GFP_KERNEL);
+ if (!z2->rx_buf)
+ return -ENOMEM;
+
+ z2->spidev = spi;
+ init_completion(&z2->boot_irq);
+ spi_set_drvdata(spi, z2);
+
+ /* Reset the device on boot */
+ z2->reset_gpio = devm_gpiod_get(dev, "reset", GPIOD_OUT_HIGH);
+ if (IS_ERR(z2->reset_gpio))
+ return dev_err_probe(dev, PTR_ERR(z2->reset_gpio), "unable to get reset\n");
+
+ error = devm_request_threaded_irq(dev, z2->spidev->irq, NULL,
+ apple_z2_irq, IRQF_ONESHOT | IRQF_NO_AUTOEN,
+ "apple-z2-irq", z2);
+ if (error)
+ return dev_err_probe(dev, error, "unable to request irq\n");
+
+ error = device_property_read_string(dev, "firmware-name", &z2->fw_name);
+ if (error)
+ return dev_err_probe(dev, error, "unable to get firmware name\n");
+
+ z2->input_dev = devm_input_allocate_device(dev);
+ if (!z2->input_dev)
+ return -ENOMEM;
+ z2->input_dev->name = (char *)spi_get_device_id(spi)->driver_data;
+ z2->input_dev->phys = "apple_z2";
+ z2->input_dev->id.bustype = BUS_SPI;
+
+ /* Allocate the axes before setting from DT */
+ input_set_abs_params(z2->input_dev, ABS_MT_POSITION_X, 0, 0, 0, 0);
+ input_set_abs_params(z2->input_dev, ABS_MT_POSITION_Y, 0, 0, 0, 0);
+ touchscreen_parse_properties(z2->input_dev, true, &z2->props);
+ input_abs_set_res(z2->input_dev, ABS_MT_POSITION_X, 100);
+ input_abs_set_res(z2->input_dev, ABS_MT_POSITION_Y, 100);
+ input_set_abs_params(z2->input_dev, ABS_MT_WIDTH_MAJOR, 0, 65535, 0, 0);
+ input_set_abs_params(z2->input_dev, ABS_MT_WIDTH_MINOR, 0, 65535, 0, 0);
+ input_set_abs_params(z2->input_dev, ABS_MT_TOUCH_MAJOR, 0, 65535, 0, 0);
+ input_set_abs_params(z2->input_dev, ABS_MT_TOUCH_MINOR, 0, 65535, 0, 0);
+ input_set_abs_params(z2->input_dev, ABS_MT_ORIENTATION, -32768, 32767, 0, 0);
+
+ error = input_mt_init_slots(z2->input_dev, 256, INPUT_MT_DIRECT);
+ if (error)
+ return dev_err_probe(dev, error, "unable to initialize multitouch slots\n");
+
+ error = input_register_device(z2->input_dev);
+ if (error)
+ return dev_err_probe(dev, error, "unable to register input device\n");
+
+ /* Wait for device reset to finish */
+ usleep_range(5000, 10000);
+ error = apple_z2_boot(z2);
+ if (error)
+ return error;
+ return 0;
+}
+
+static void apple_z2_shutdown(struct spi_device *spi)
+{
+ struct apple_z2 *z2 = spi_get_drvdata(spi);
+
+ disable_irq(z2->spidev->irq);
+ gpiod_direction_output(z2->reset_gpio, 1);
+ z2->booted = false;
+}
+
+static int apple_z2_suspend(struct device *dev)
+{
+ apple_z2_shutdown(to_spi_device(dev));
+ return 0;
+}
+
+static int apple_z2_resume(struct device *dev)
+{
+ struct apple_z2 *z2 = spi_get_drvdata(to_spi_device(dev));
+
+ return apple_z2_boot(z2);
+}
+
+static DEFINE_SIMPLE_DEV_PM_OPS(apple_z2_pm, apple_z2_suspend, apple_z2_resume);
+
+static const struct of_device_id apple_z2_of_match[] = {
+ { .compatible = "apple,j293-touchbar" },
+ { .compatible = "apple,j493-touchbar" },
+ {}
+};
+MODULE_DEVICE_TABLE(of, apple_z2_of_match);
+
+static struct spi_device_id apple_z2_of_id[] = {
+ { .name = "j293-touchbar", .driver_data = (kernel_ulong_t)"MacBookPro17,1 Touch Bar" },
+ { .name = "j493-touchbar", .driver_data = (kernel_ulong_t)"Mac14,7 Touch Bar" },
+ {}
+};
+MODULE_DEVICE_TABLE(spi, apple_z2_of_id);
+
+static struct spi_driver apple_z2_driver = {
+ .driver = {
+ .name = "apple-z2",
+ .pm = pm_sleep_ptr(&apple_z2_pm),
+ .of_match_table = apple_z2_of_match,
+ .probe_type = PROBE_PREFER_ASYNCHRONOUS,
+ },
+ .id_table = apple_z2_of_id,
+ .probe = apple_z2_probe,
+ .remove = apple_z2_shutdown,
+};
+
+module_spi_driver(apple_z2_driver);
+
+MODULE_LICENSE("GPL");
+MODULE_FIRMWARE("apple/dfrmtfw-*.bin");
+MODULE_DESCRIPTION("Apple Z2 touchscreens driver");

--
2.48.1