path: root/drivers/input/touchscreen/apple_z2.c

// 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_REPLY_INTERRUPT_DATA    0xE1
#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;

	if (z2->rx_buf[0] != APPLE_Z2_REPLY_INTERRUPT_DATA)
		return 0;

	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[