linux-surface/patches/6.4/0005-ithc.patch

From b8fd34edd85322e3106a5aa6ddc375673a023c40 Mon Sep 17 00:00:00 2001
From: Dorian Stoll <dorian.stoll@tmsp.io>
Date: Sun, 11 Dec 2022 12:03:38 +0100
Subject: [PATCH] iommu: intel: Disable source id verification for ITHC

Signed-off-by: Dorian Stoll <dorian.stoll@tmsp.io>
Patchset: ithc
---
 drivers/iommu/intel/irq_remapping.c | 16 ++++++++++++++++
 1 file changed, 16 insertions(+)

diff --git a/drivers/iommu/intel/irq_remapping.c b/drivers/iommu/intel/irq_remapping.c
index a1b987335b31..970805409470 100644
--- a/drivers/iommu/intel/irq_remapping.c
+++ b/drivers/iommu/intel/irq_remapping.c
@@ -390,6 +390,22 @@ static int set_msi_sid(struct irte *irte, struct pci_dev *dev)
 	data.busmatch_count = 0;
 	pci_for_each_dma_alias(dev, set_msi_sid_cb, &data);
 
+	/*
+	 * The Intel Touch Host Controller is at 00:10.6, but for some reason
+	 * the MSI interrupts have request id 01:05.0.
+	 * Disable id verification to work around this.
+	 * FIXME Find proper fix or turn this into a quirk.
+	 */
+	if (dev->vendor == PCI_VENDOR_ID_INTEL && (dev->class >> 8) == PCI_CLASS_INPUT_PEN) {
+		switch(dev->device) {
+		case 0x98d0: case 0x98d1: // LKF
+		case 0xa0d0: case 0xa0d1: // TGL LP
+		case 0x43d0: case 0x43d1: // TGL H
+			set_irte_sid(irte, SVT_NO_VERIFY, SQ_ALL_16, 0);
+			return 0;
+		}
+	}
+
 	/*
 	 * DMA alias provides us with a PCI device and alias.  The only case
 	 * where the it will return an alias on a different bus than the
-- 
2.41.0

From 357c5b10962caedb479db99d1383a31f9e77111f Mon Sep 17 00:00:00 2001
From: Dorian Stoll <dorian.stoll@tmsp.io>
Date: Sun, 11 Dec 2022 12:10:54 +0100
Subject: [PATCH] hid: Add support for Intel Touch Host Controller

Based on quo/ithc-linux@55803a2

Signed-off-by: Dorian Stoll <dorian.stoll@tmsp.io>
Patchset: ithc
---
 drivers/hid/Kconfig           |   2 +
 drivers/hid/Makefile          |   1 +
 drivers/hid/ithc/Kbuild       |   6 +
 drivers/hid/ithc/Kconfig      |  12 +
 drivers/hid/ithc/ithc-debug.c |  96 ++++++
 drivers/hid/ithc/ithc-dma.c   | 258 ++++++++++++++++
 drivers/hid/ithc/ithc-dma.h   |  67 +++++
 drivers/hid/ithc/ithc-main.c  | 534 ++++++++++++++++++++++++++++++++++
 drivers/hid/ithc/ithc-regs.c  |  64 ++++
 drivers/hid/ithc/ithc-regs.h  | 186 ++++++++++++
 drivers/hid/ithc/ithc.h       |  60 ++++
 11 files changed, 1286 insertions(+)
 create mode 100644 drivers/hid/ithc/Kbuild
 create mode 100644 drivers/hid/ithc/Kconfig
 create mode 100644 drivers/hid/ithc/ithc-debug.c
 create mode 100644 drivers/hid/ithc/ithc-dma.c
 create mode 100644 drivers/hid/ithc/ithc-dma.h
 create mode 100644 drivers/hid/ithc/ithc-main.c
 create mode 100644 drivers/hid/ithc/ithc-regs.c
 create mode 100644 drivers/hid/ithc/ithc-regs.h
 create mode 100644 drivers/hid/ithc/ithc.h

diff --git a/drivers/hid/Kconfig b/drivers/hid/Kconfig
index dcedd5b90f35..847c6b07914d 100644
--- a/drivers/hid/Kconfig
+++ b/drivers/hid/Kconfig
@@ -1318,4 +1318,6 @@ source "drivers/hid/surface-hid/Kconfig"
 
 source "drivers/hid/ipts/Kconfig"
 
+source "drivers/hid/ithc/Kconfig"
+
 endif # HID_SUPPORT
diff --git a/drivers/hid/Makefile b/drivers/hid/Makefile
index 285e12d95b0e..a3ff62e922f1 100644
--- a/drivers/hid/Makefile
+++ b/drivers/hid/Makefile
@@ -169,3 +169,4 @@ obj-$(CONFIG_AMD_SFH_HID)       += amd-sfh-hid/
 obj-$(CONFIG_SURFACE_HID_CORE)  += surface-hid/
 
 obj-$(CONFIG_HID_IPTS)          += ipts/
+obj-$(CONFIG_HID_ITHC)          += ithc/
diff --git a/drivers/hid/ithc/Kbuild b/drivers/hid/ithc/Kbuild
new file mode 100644
index 000000000000..aea83f2ac07b
--- /dev/null
+++ b/drivers/hid/ithc/Kbuild
@@ -0,0 +1,6 @@
+obj-$(CONFIG_HID_ITHC) := ithc.o
+
+ithc-objs := ithc-main.o ithc-regs.o ithc-dma.o ithc-debug.o
+
+ccflags-y := -std=gnu11 -Wno-declaration-after-statement
+
diff --git a/drivers/hid/ithc/Kconfig b/drivers/hid/ithc/Kconfig
new file mode 100644
index 000000000000..ede713023609
--- /dev/null
+++ b/drivers/hid/ithc/Kconfig
@@ -0,0 +1,12 @@
+config HID_ITHC
+	tristate "Intel Touch Host Controller"
+	depends on PCI
+	depends on HID
+	help
+	  Say Y here if your system has a touchscreen using Intels
+	  Touch Host Controller (ITHC / IPTS) technology.
+
+	  If unsure say N.
+
+	  To compile this driver as a module, choose M here: the
+	  module will be called ithc.
diff --git a/drivers/hid/ithc/ithc-debug.c b/drivers/hid/ithc/ithc-debug.c
new file mode 100644
index 000000000000..57bf125c45bd
--- /dev/null
+++ b/drivers/hid/ithc/ithc-debug.c
@@ -0,0 +1,96 @@
+#include "ithc.h"
+
+void ithc_log_regs(struct ithc *ithc) {
+	if (!ithc->prev_regs) return;
+	u32 __iomem *cur = (__iomem void*)ithc->regs;
+	u32 *prev = (void*)ithc->prev_regs;
+	for (int i = 1024; i < sizeof *ithc->regs / 4; i++) {
+		u32 x = readl(cur + i);
+		if (x != prev[i]) {
+			pci_info(ithc->pci, "reg %04x: %08x -> %08x\n", i * 4, prev[i], x);
+			prev[i] = x;
+		}
+	}
+}
+
+static ssize_t ithc_debugfs_cmd_write(struct file *f, const char __user *buf, size_t len, loff_t *offset) {
+	struct ithc *ithc = file_inode(f)->i_private;
+	char cmd[256];
+	if (!ithc || !ithc->pci) return -ENODEV;
+	if (!len) return -EINVAL;
+	if (len >= sizeof cmd) return -EINVAL;
+	if (copy_from_user(cmd, buf, len)) return -EFAULT;
+	cmd[len] = 0;
+	if (cmd[len-1] == '\n') cmd[len-1] = 0;
+	pci_info(ithc->pci, "debug command: %s\n", cmd);
+	u32 n = 0;
+	const char *s = cmd + 1;
+	u32 a[32];
+	while (*s && *s != '\n') {
+		if (n >= ARRAY_SIZE(a)) return -EINVAL;
+		if (*s++ != ' ') return -EINVAL;
+		char *e;
+		a[n++] = simple_strtoul(s, &e, 0);
+		if (e == s) return -EINVAL;
+		s = e;
+	}
+	ithc_log_regs(ithc);
+	switch(cmd[0]) {
+	case 'x': // reset
+		ithc_reset(ithc);
+		break;
+	case 'w': // write register: offset mask value
+		if (n != 3 || (a[0] & 3)) return -EINVAL;
+		pci_info(ithc->pci, "debug write 0x%04x = 0x%08x (mask 0x%08x)\n", a[0], a[2], a[1]);
+		bitsl(((__iomem u32 *)ithc->regs) + a[0] / 4, a[1], a[2]);
+		break;
+	case 'r': // read register: offset
+		if (n != 1 || (a[0] & 3)) return -EINVAL;
+		pci_info(ithc->pci, "debug read 0x%04x = 0x%08x\n", a[0], readl(((__iomem u32 *)ithc->regs) + a[0] / 4));
+		break;
+	case 's': // spi command: cmd offset len data...
+		// read config: s 4 0 64 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
+		// set touch cfg: s 6 12 4 XX
+		if (n < 3 || a[2] > (n - 3) * 4) return -EINVAL;
+		pci_info(ithc->pci, "debug spi command %u with %u bytes of data\n", a[0], a[2]);
+		if (!CHECK(ithc_spi_command, ithc, a[0], a[1], a[2], a + 3))
+			for (u32 i = 0; i < (a[2] + 3) / 4; i++) pci_info(ithc->pci, "resp %u = 0x%08x\n", i, a[3+i]);
+		break;
+	case 'd': // dma command: cmd len data...
+		// get report descriptor: d 7 8 0 0
+		// enable multitouch: d 3 2 0x0105
+		if (n < 2 || a[1] > (n - 2) * 4) return -EINVAL;
+		pci_info(ithc->pci, "debug dma command %u with %u bytes of data\n", a[0], a[1]);
+		if (ithc_dma_tx(ithc, a[0], a[1], a + 2)) pci_err(ithc->pci, "dma tx failed\n");
+		break;
+	default:
+		return -EINVAL;
+	}
+	ithc_log_regs(ithc);
+	return len;
+}
+
+static const struct file_operations ithc_debugfops_cmd = {
+	.owner = THIS_MODULE,
+	.write = ithc_debugfs_cmd_write,
+};
+
+static void ithc_debugfs_devres_release(struct device *dev, void *res) {
+	struct dentry **dbgm = res;
+	if (*dbgm) debugfs_remove_recursive(*dbgm);
+}
+
+int ithc_debug_init(struct ithc *ithc) {
+	struct dentry **dbgm = devres_alloc(ithc_debugfs_devres_release, sizeof *dbgm, GFP_KERNEL);
+	if (!dbgm) return -ENOMEM;
+	devres_add(&ithc->pci->dev, dbgm);
+	struct dentry *dbg = debugfs_create_dir(DEVNAME, NULL);
+	if (IS_ERR(dbg)) return PTR_ERR(dbg);
+	*dbgm = dbg;
+
+	struct dentry *cmd = debugfs_create_file("cmd", 0220, dbg, ithc, &ithc_debugfops_cmd);
+	if (IS_ERR(cmd)) return PTR_ERR(cmd);
+
+	return 0;
+}
+
diff --git a/drivers/hid/ithc/ithc-dma.c b/drivers/hid/ithc/ithc-dma.c
new file mode 100644
index 000000000000..7e89b3496918
--- /dev/null
+++ b/drivers/hid/ithc/ithc-dma.c
@@ -0,0 +1,258 @@
+#include "ithc.h"
+
+static int ithc_dma_prd_alloc(struct ithc *ithc, struct ithc_dma_prd_buffer *p, unsigned num_buffers, unsigned num_pages, enum dma_data_direction dir) {
+	p->num_pages = num_pages;
+	p->dir = dir;
+	p->size = round_up(num_buffers * num_pages * sizeof(struct ithc_phys_region_desc), PAGE_SIZE);
+	p->addr = dmam_alloc_coherent(&ithc->pci->dev, p->size, &p->dma_addr, GFP_KERNEL);
+	if (!p->addr) return -ENOMEM;
+	if (p->dma_addr & (PAGE_SIZE - 1)) return -EFAULT;
+	return 0;
+}
+
+struct ithc_sg_table {
+	void *addr;
+	struct sg_table sgt;
+	enum dma_data_direction dir;
+};
+static void ithc_dma_sgtable_free(struct sg_table *sgt) {
+	struct scatterlist *sg;
+	int i;
+	for_each_sgtable_sg(sgt, sg, i) {
+		struct page *p = sg_page(sg);
+		if (p) __free_page(p);
+	}
+	sg_free_table(sgt);
+}
+static void ithc_dma_data_devres_release(struct device *dev, void *res) {
+	struct ithc_sg_table *sgt = res;
+	if (sgt->addr) vunmap(sgt->addr);
+	dma_unmap_sgtable(dev, &sgt->sgt, sgt->dir, 0);
+	ithc_dma_sgtable_free(&sgt->sgt);
+}
+
+static int ithc_dma_data_alloc(struct ithc* ithc, struct ithc_dma_prd_buffer *prds, struct ithc_dma_data_buffer *b) {
+	// We don't use dma_alloc_coherent for data buffers, because they don't have to be contiguous (we can use one PRD per page) or coherent (they are unidirectional).
+	// Instead we use an sg_table of individually allocated pages (5.13 has dma_alloc_noncontiguous for this, but we'd like to support 5.10 for now).
+	struct page *pages[16];
+	if (prds->num_pages == 0 || prds->num_pages > ARRAY_SIZE(pages)) return -EINVAL;
+	b->active_idx = -1;
+	struct ithc_sg_table *sgt = devres_alloc(ithc_dma_data_devres_release, sizeof *sgt, GFP_KERNEL);
+	if (!sgt) return -ENOMEM;
+	sgt->dir = prds->dir;
+	if (!sg_alloc_table(&sgt->sgt, prds->num_pages, GFP_KERNEL)) {
+		struct scatterlist *sg;
+		int i;
+		bool ok = true;
+		for_each_sgtable_sg(&sgt->sgt, sg, i) {
+			struct page *p = pages[i] = alloc_page(GFP_KERNEL | __GFP_ZERO); // don't need __GFP_DMA for PCI DMA
+			if (!p) { ok = false; break; }
+			sg_set_page(sg, p, PAGE_SIZE, 0);
+		}
+		if (ok && !dma_map_sgtable(&ithc->pci->dev, &sgt->sgt, prds->dir, 0)) {
+			devres_add(&ithc->pci->dev, sgt);
+			b->sgt = &sgt->sgt;
+			b->addr = sgt->addr = vmap(pages, prds->num_pages, 0, PAGE_KERNEL);
+			if (!b->addr) return -ENOMEM;
+			return 0;
+		}
+		ithc_dma_sgtable_free(&sgt->sgt);
+	}
+	devres_free(sgt);
+	return -ENOMEM;
+}
+
+static int ithc_dma_data_buffer_put(struct ithc *ithc, struct ithc_dma_prd_buffer *prds, struct ithc_dma_data_buffer *b, unsigned idx) {
+	struct ithc_phys_region_desc *prd = prds->addr;
+	prd += idx * prds->num_pages;
+	if (b->active_idx >= 0) { pci_err(ithc->pci, "buffer already active\n"); return -EINVAL; }
+	b->active_idx = idx;
+	if (prds->dir == DMA_TO_DEVICE) {
+		if (b->data_size > PAGE_SIZE) return -EINVAL;
+		prd->addr = sg_dma_address(b->sgt->sgl) >> 10;
+		prd->size = b->data_size | PRD_FLAG_END;
+		flush_kernel_vmap_range(b->addr, b->data_size);
+	} else if (prds->dir == DMA_FROM_DEVICE) {
+		struct scatterlist *sg;
+		int i;
+		for_each_sgtable_dma_sg(b->sgt, sg, i) {
+			prd->addr = sg_dma_address(sg) >> 10;
+			prd->size = sg_dma_len(sg);
+			prd++;
+		}
+		prd[-1].size |= PRD_FLAG_END;
+	}
+	dma_wmb(); // for the prds
+	dma_sync_sgtable_for_device(&ithc->pci->dev, b->sgt, prds->dir);
+	return 0;
+}
+
+static int ithc_dma_data_buffer_get(struct ithc *ithc, struct ithc_dma_prd_buffer *prds, struct ithc_dma_data_buffer *b, unsigned idx) {
+	struct ithc_phys_region_desc *prd = prds->addr;
+	prd += idx * prds->num_pages;
+	if (b->active_idx != idx) { pci_err(ithc->pci, "wrong buffer index\n"); return -EINVAL; }
+	b->active_idx = -1;
+	if (prds->dir == DMA_FROM_DEVICE) {
+		dma_rmb(); // for the prds
+		b->data_size = 0;
+		struct scatterlist *sg;
+		int i;
+		for_each_sgtable_dma_sg(b->sgt, sg, i) {
+			unsigned size = prd->size;
+			b->data_size += size & PRD_SIZE_MASK;
+			if (size & PRD_FLAG_END) break;
+			if ((size & PRD_SIZE_MASK) != sg_dma_len(sg)) { pci_err(ithc->pci, "truncated prd\n"); break; }
+			prd++;
+		}
+		invalidate_kernel_vmap_range(b->addr, b->data_size);
+	}
+	dma_sync_sgtable_for_cpu(&ithc->pci->dev, b->sgt, prds->dir);
+	return 0;
+}
+
+int ithc_dma_rx_init(struct ithc *ithc, u8 channel, const char *devname) {
+	struct ithc_dma_rx *rx = &ithc->dma_rx[channel];
+	mutex_init(&rx->mutex);
+	u32 buf_size = DEVCFG_DMA_RX_SIZE(ithc->config.dma_buf_sizes);
+	unsigned num_pages = (buf_size + PAGE_SIZE - 1) / PAGE_SIZE;
+	pci_dbg(ithc->pci, "allocating rx buffers: num = %u, size = %u, pages = %u\n", NUM_RX_BUF, buf_size, num_pages);
+	CHECK_RET(ithc_dma_prd_alloc, ithc, &rx->prds, NUM_RX_BUF, num_pages, DMA_FROM_DEVICE);
+	for (unsigned i = 0; i < NUM_RX_BUF; i++)
+		CHECK_RET(ithc_dma_data_alloc, ithc, &rx->prds, &rx->bufs[i]);
+	writeb(DMA_RX_CONTROL2_RESET, &ithc->regs->dma_rx[channel].control2);
+	lo_hi_writeq(rx->prds.dma_addr, &ithc->regs->dma_rx[channel].addr);
+	writeb(NUM_RX_BUF - 1, &ithc->regs->dma_rx[channel].num_bufs);
+	writeb(num_pages - 1, &ithc->regs->dma_rx[channel].num_prds);
+	u8 head = readb(&ithc->regs->dma_rx[channel].head);
+	if (head) { pci_err(ithc->pci, "head is nonzero (%u)\n", head); return -EIO; }
+	for (unsigned i = 0; i < NUM_RX_BUF; i++)
+		CHECK_RET(ithc_dma_data_buffer_put, ithc, &rx->prds, &rx->bufs[i], i);
+	writeb(head ^ DMA_RX_WRAP_FLAG, &ithc->regs->dma_rx[channel].tail);
+	return 0;
+}
+void ithc_dma_rx_enable(struct ithc *ithc, u8 channel) {
+	bitsb_set(&ithc->regs->dma_rx[channel].control, DMA_RX_CONTROL_ENABLE | DMA_RX_CONTROL_IRQ_ERROR | DMA_RX_CONTROL_IRQ_DATA);
+	CHECK(waitl, ithc, &ithc->regs->dma_rx[1].status, DMA_RX_STATUS_ENABLED, DMA_RX_STATUS_ENABLED);
+}
+
+int ithc_dma_tx_init(struct ithc *ithc) {
+	struct ithc_dma_tx *tx = &ithc->dma_tx;
+	mutex_init(&tx->mutex);
+	tx->max_size = DEVCFG_DMA_TX_SIZE(ithc->config.dma_buf_sizes);
+	unsigned num_pages = (tx->max_size + PAGE_SIZE - 1) / PAGE_SIZE;
+	pci_dbg(ithc->pci, "allocating tx buffers: size = %u, pages = %u\n", tx->max_size, num_pages);
+	CHECK_RET(ithc_dma_prd_alloc, ithc, &tx->prds, 1, num_pages, DMA_TO_DEVICE);
+	CHECK_RET(ithc_dma_data_alloc, ithc, &tx->prds, &tx->buf);
+	lo_hi_writeq(tx->prds.dma_addr, &ithc->regs->dma_tx.addr);
+	writeb(num_pages - 1, &ithc->regs->dma_tx.num_prds);
+	CHECK_RET(ithc_dma_data_buffer_put, ithc, &ithc->dma_tx.prds, &ithc->dma_tx.buf, 0);
+	return 0;
+}
+
+static int ithc_dma_rx_process_buf(struct ithc *ithc, struct ithc_dma_data_buffer *data, u8 channel, u8 buf) {
+	if (buf >= NUM_RX_BUF) {
+		pci_err(ithc->pci, "invalid dma ringbuffer index\n");
+		return -EINVAL;
+	}
+	ithc_set_active(ithc);
+	u32 len = data->data_size;
+	struct ithc_dma_rx_header *hdr = data->addr;
+	u8 *hiddata = (void *)(hdr + 1);
+	if (len >= sizeof *hdr && hdr->code == DMA_RX_CODE_RESET) {
+		CHECK(ithc_reset, ithc);
+	} else if (len < sizeof *hdr || len != sizeof *hdr + hdr->data_size) {
+		if (hdr->code == DMA_RX_CODE_INPUT_REPORT) {
+			// When the CPU enters a low power state during DMA, we can get truncated messages.
+			// Typically this will be a single touch HID report that is only 1 byte, or a multitouch report that is 257 bytes.
+			// See also ithc_set_active().
+		} else {
+			pci_err(ithc->pci, "invalid dma rx data! channel %u, buffer %u, size %u, code %u, data size %u\n", channel, buf, len, hdr->code, hdr->data_size);
+			print_hex_dump_debug(DEVNAME " data: ", DUMP_PREFIX_OFFSET, 32, 1, hdr, min(len, 0x400u), 0);
+		}
+	} else if (hdr->code == DMA_RX_CODE_REPORT_DESCRIPTOR && hdr->data_size > 8) {
+		CHECK(hid_parse_report, ithc->hid, hiddata + 8, hdr->data_size - 8);
+		WRITE_ONCE(ithc->hid_parse_done, true);
+		wake_up(&ithc->wait_hid_parse);
+	} else if (hdr->code == DMA_RX_CODE_INPUT_REPORT) {
+		CHECK(hid_input_report, ithc->hid, HID_INPUT_REPORT, hiddata, hdr->data_size, 1);
+	} else if (hdr->code == DMA_RX_CODE_FEATURE_REPORT) {
+		bool done = false;
+		mutex_lock(&ithc->hid_get_feature_mutex);
+		if (ithc->hid_get_feature_buf) {
+			if (hdr->data_size < ithc->hid_get_feature_size) ithc->hid_get_feature_size = hdr->data_size;
+			memcpy(ithc->hid_get_feature_buf, hiddata, ithc->hid_get_feature_size);
+			ithc->hid_get_feature_buf = NULL;
+			done = true;
+		}
+		mutex_unlock(&ithc->hid_get_feature_mutex);
+		if (done) wake_up(&ithc->wait_hid_get_feature);
+		else CHECK(hid_input_report, ithc->hid, HID_FEATURE_REPORT, hiddata, hdr->data_size, 1);
+	} else {
+		pci_dbg(ithc->pci, "unhandled dma rx data! channel %u, buffer %u, size %u, code %u\n", channel, buf, len, hdr->code);
+		print_hex_dump_debug(DEVNAME " data: ", DUMP_PREFIX_OFFSET, 32, 1, hdr, min(len, 0x400u), 0);
+	}
+	return 0;
+}
+
+static int ithc_dma_rx_unlocked(struct ithc *ithc, u8 channel) {
+	struct ithc_dma_rx *rx = &ithc->dma_rx[channel];
+	unsigned n = rx->num_received;
+	u8 head_wrap = readb(&ithc->regs->dma_rx[channel].head);
+	while (1) {
+		u8 tail = n % NUM_RX_BUF;
+		u8 tail_wrap = tail | ((n / NUM_RX_BUF) & 1 ? 0 : DMA_RX_WRAP_FLAG);
+		writeb(tail_wrap, &ithc->regs->dma_rx[channel].tail);
+		// ringbuffer is full if tail_wrap == head_wrap
+		// ringbuffer is empty if tail_wrap == head_wrap ^ WRAP_FLAG
+		if (tail_wrap == (head_wrap ^ DMA_RX_WRAP_FLAG)) return 0;
+
+		// take the buffer that the device just filled
+		struct ithc_dma_data_buffer *b = &rx->bufs[n % NUM_RX_BUF];
+		CHECK_RET(ithc_dma_data_buffer_get, ithc, &rx->prds, b, tail);
+		rx->num_received = ++n;
+
+		// process data
+		CHECK(ithc_dma_rx_process_buf, ithc, b, channel, tail);
+
+		// give the buffer back to the device
+		CHECK_RET(ithc_dma_data_buffer_put, ithc, &rx->prds, b, tail);
+	}
+}
+int ithc_dma_rx(struct ithc *ithc, u8 channel) {
+	struct ithc_dma_rx *rx = &ithc->dma_rx[channel];
+	mutex_lock(&rx->mutex);
+	int ret = ithc_dma_rx_unlocked(ithc, channel);
+	mutex_unlock(&rx->mutex);
+	return ret;
+}
+
+static int ithc_dma_tx_unlocked(struct ithc *ithc, u32 cmdcode, u32 datasize, void *data) {
+	pci_dbg(ithc->pci, "dma tx command %u, size %u\n", cmdcode, datasize);
+	struct ithc_dma_tx_header *hdr;
+	u8 padding = datasize & 3 ? 4 - (datasize & 3) : 0;
+	unsigned fullsize = sizeof *hdr + datasize + padding;
+	if (fullsize > ithc->dma_tx.max_size || fullsize > PAGE_SIZE) return -EINVAL;
+	CHECK_RET(ithc_dma_data_buffer_get, ithc, &ithc->dma_tx.prds, &ithc->dma_tx.buf, 0);
+
+	ithc->dma_tx.buf.data_size = fullsize;
+	hdr = ithc->dma_tx.buf.addr;
+	hdr->code = cmdcode;
+	hdr->data_size = datasize;
+	u8 *dest = (void *)(hdr + 1);
+	memcpy(dest, data, datasize);
+	dest += datasize;
+	for (u8 p = 0; p < padding; p++) *dest++ = 0;
+	CHECK_RET(ithc_dma_data_buffer_put, ithc, &ithc->dma_tx.prds, &ithc->dma_tx.buf, 0);
+
+	bitsb_set(&ithc->regs->dma_tx.control, DMA_TX_CONTROL_SEND);
+	CHECK_RET(waitb, ithc, &ithc->regs->dma_tx.control, DMA_TX_CONTROL_SEND, 0);
+	writel(DMA_TX_STATUS_DONE, &ithc->regs->dma_tx.status);
+	return 0;
+}
+int ithc_dma_tx(struct ithc *ithc, u32 cmdcode, u32 datasize, void *data) {
+	mutex_lock(&ithc->dma_tx.mutex);
+	int ret = ithc_dma_tx_unlocked(ithc, cmdcode, datasize, data);
+	mutex_unlock(&ithc->dma_tx.mutex);
+	return ret;
+}
+
diff --git a/drivers/hid/ithc/ithc-dma.h b/drivers/hid/ithc/ithc-dma.h
new file mode 100644
index 000000000000..d9f2c19a13f3
--- /dev/null
+++ b/drivers/hid/ithc/ithc-dma.h
@@ -0,0 +1,67 @@
+#define PRD_SIZE_MASK            0xffffff
+#define PRD_FLAG_END             0x1000000
+#define PRD_FLAG_SUCCESS         0x2000000
+#define PRD_FLAG_ERROR           0x4000000
+
+struct ithc_phys_region_desc {
+	u64 addr; // physical addr/1024
+	u32 size; // num bytes, PRD_FLAG_END marks last prd for data split over multiple prds
+	u32 unused;
+};
+
+#define DMA_RX_CODE_INPUT_REPORT          3
+#define DMA_RX_CODE_FEATURE_REPORT        4
+#define DMA_RX_CODE_REPORT_DESCRIPTOR     5
+#define DMA_RX_CODE_RESET                 7
+
+struct ithc_dma_rx_header {
+	u32 code;
+	u32 data_size;
+	u32 _unknown[14];
+};
+
+#define DMA_TX_CODE_SET_FEATURE           3
+#define DMA_TX_CODE_GET_FEATURE           4
+#define DMA_TX_CODE_OUTPUT_REPORT         5
+#define DMA_TX_CODE_GET_REPORT_DESCRIPTOR 7
+
+struct ithc_dma_tx_header {
+	u32 code;
+	u32 data_size;
+};
+
+struct ithc_dma_prd_buffer {
+	void *addr;
+	dma_addr_t dma_addr;
+	u32 size;
+	u32 num_pages; // per data buffer
+	enum dma_data_direction dir;
+};
+
+struct ithc_dma_data_buffer {
+	void *addr;
+	struct sg_table *sgt;
+	int active_idx;
+	u32 data_size;
+};
+
+struct ithc_dma_tx {
+	struct mutex mutex;
+	u32 max_size;
+	struct ithc_dma_prd_buffer prds;
+	struct ithc_dma_data_buffer buf;
+};
+
+struct ithc_dma_rx {
+	struct mutex mutex;
+	u32 num_received;
+	struct ithc_dma_prd_buffer prds;
+	struct ithc_dma_data_buffer bufs[NUM_RX_BUF];
+};
+
+int ithc_dma_rx_init(struct ithc *ithc, u8 channel, const char *devname);
+void ithc_dma_rx_enable(struct ithc *ithc, u8 channel);
+int ithc_dma_tx_init(struct ithc *ithc);
+int ithc_dma_rx(struct ithc *ithc, u8 channel);
+int ithc_dma_tx(struct ithc *ithc, u32 cmdcode, u32 datasize, void *cmddata);
+
diff --git a/drivers/hid/ithc/ithc-main.c b/drivers/hid/ithc/ithc-main.c
new file mode 100644
index 000000000000..09512b9cb4d3
--- /dev/null
+++ b/drivers/hid/ithc/ithc-main.c
@@ -0,0 +1,534 @@
+#include "ithc.h"
+
+MODULE_DESCRIPTION("Intel Touch Host Controller driver");
+MODULE_LICENSE("Dual BSD/GPL");
+
+// Lakefield
+#define PCI_DEVICE_ID_INTEL_THC_LKF_PORT1    0x98d0
+#define PCI_DEVICE_ID_INTEL_THC_LKF_PORT2    0x98d1
+// Tiger Lake
+#define PCI_DEVICE_ID_INTEL_THC_TGL_LP_PORT1 0xa0d0
+#define PCI_DEVICE_ID_INTEL_THC_TGL_LP_PORT2 0xa0d1
+#define PCI_DEVICE_ID_INTEL_THC_TGL_H_PORT1  0x43d0
+#define PCI_DEVICE_ID_INTEL_THC_TGL_H_PORT2  0x43d1
+// Alder Lake
+#define PCI_DEVICE_ID_INTEL_THC_ADL_S_PORT1  0x7ad8
+#define PCI_DEVICE_ID_INTEL_THC_ADL_S_PORT2  0x7ad9
+#define PCI_DEVICE_ID_INTEL_THC_ADL_P_PORT1  0x51d0
+#define PCI_DEVICE_ID_INTEL_THC_ADL_P_PORT2  0x51d1
+#define PCI_DEVICE_ID_INTEL_THC_ADL_M_PORT1  0x54d0
+#define PCI_DEVICE_ID_INTEL_THC_ADL_M_PORT2  0x54d1
+// Raptor Lake
+#define PCI_DEVICE_ID_INTEL_THC_RPL_S_PORT1  0x7a58
+#define PCI_DEVICE_ID_INTEL_THC_RPL_S_PORT2  0x7a59
+// Meteor Lake
+#define PCI_DEVICE_ID_INTEL_THC_MTL_PORT1    0x7e48
+#define PCI_DEVICE_ID_INTEL_THC_MTL_PORT2    0x7e4a
+
+static const struct pci_device_id ithc_pci_tbl[] = {
+	{ PCI_DEVICE(PCI_VENDOR_ID_INTEL, PCI_DEVICE_ID_INTEL_THC_LKF_PORT1) },
+	{ PCI_DEVICE(PCI_VENDOR_ID_INTEL, PCI_DEVICE_ID_INTEL_THC_LKF_PORT2) },
+	{ PCI_DEVICE(PCI_VENDOR_ID_INTEL, PCI_DEVICE_ID_INTEL_THC_TGL_LP_PORT1) },
+	{ PCI_DEVICE(PCI_VENDOR_ID_INTEL, PCI_DEVICE_ID_INTEL_THC_TGL_LP_PORT2) },
+	{ PCI_DEVICE(PCI_VENDOR_ID_INTEL, PCI_DEVICE_ID_INTEL_THC_TGL_H_PORT1) },
+	{ PCI_DEVICE(PCI_VENDOR_ID_INTEL, PCI_DEVICE_ID_INTEL_THC_TGL_H_PORT2) },
+	{ PCI_DEVICE(PCI_VENDOR_ID_INTEL, PCI_DEVICE_ID_INTEL_THC_ADL_S_PORT1) },
+	{ PCI_DEVICE(PCI_VENDOR_ID_INTEL, PCI_DEVICE_ID_INTEL_THC_ADL_S_PORT2) },
+	{ PCI_DEVICE(PCI_VENDOR_ID_INTEL, PCI_DEVICE_ID_INTEL_THC_ADL_P_PORT1) },
+	{ PCI_DEVICE(PCI_VENDOR_ID_INTEL, PCI_DEVICE_ID_INTEL_THC_ADL_P_PORT2) },
+	{ PCI_DEVICE(PCI_VENDOR_ID_INTEL, PCI_DEVICE_ID_INTEL_THC_ADL_M_PORT1) },
+	{ PCI_DEVICE(PCI_VENDOR_ID_INTEL, PCI_DEVICE_ID_INTEL_THC_ADL_M_PORT2) },
+	{ PCI_DEVICE(PCI_VENDOR_ID_INTEL, PCI_DEVICE_ID_INTEL_THC_RPL_S_PORT1) },
+	{ PCI_DEVICE(PCI_VENDOR_ID_INTEL, PCI_DEVICE_ID_INTEL_THC_RPL_S_PORT2) },
+	{ PCI_DEVICE(PCI_VENDOR_ID_INTEL, PCI_DEVICE_ID_INTEL_THC_MTL_PORT1) },
+	{ PCI_DEVICE(PCI_VENDOR_ID_INTEL, PCI_DEVICE_ID_INTEL_THC_MTL_PORT2) },
+	{}
+};
+MODULE_DEVICE_TABLE(pci, ithc_pci_tbl);
+
+// Module parameters
+
+static bool ithc_use_polling = false;
+module_param_named(poll, ithc_use_polling, bool, 0);
+MODULE_PARM_DESC(poll, "Use polling instead of interrupts");
+
+static bool ithc_use_rx0 = false;
+module_param_named(rx0, ithc_use_rx0, bool, 0);
+MODULE_PARM_DESC(rx0, "Use DMA RX channel 0");
+
+static bool ithc_use_rx1 = true;
+module_param_named(rx1, ithc_use_rx1, bool, 0);
+MODULE_PARM_DESC(rx1, "Use DMA RX channel 1");
+
+static bool ithc_log_regs_enabled = false;
+module_param_named(logregs, ithc_log_regs_enabled, bool, 0);
+MODULE_PARM_DESC(logregs, "Log changes in register values (for debugging)");
+
+// Sysfs attributes
+
+static bool ithc_is_config_valid(struct ithc *ithc) {
+	return ithc->config.device_id == DEVCFG_DEVICE_ID_TIC;
+}
+
+static ssize_t vendor_show(struct device *dev, struct device_attribute *attr, char *buf) {
+	struct ithc *ithc = dev_get_drvdata(dev);
+	if (!ithc || !ithc_is_config_valid(ithc)) return -ENODEV;
+	return sprintf(buf, "0x%04x", ithc->config.vendor_id);
+}
+static DEVICE_ATTR_RO(vendor);
+static ssize_t product_show(struct device *dev, struct device_attribute *attr, char *buf) {
+	struct ithc *ithc = dev_get_drvdata(dev);
+	if (!ithc || !ithc_is_config_valid(ithc)) return -ENODEV;
+	return sprintf(buf, "0x%04x", ithc->config.product_id);
+}
+static DEVICE_ATTR_RO(product);
+static ssize_t revision_show(struct device *dev, struct device_attribute *attr, char *buf) {
+	struct ithc *ithc = dev_get_drvdata(dev);
+	if (!ithc || !ithc_is_config_valid(ithc)) return -ENODEV;
+	return sprintf(buf, "%u", ithc->config.revision);
+}
+static DEVICE_ATTR_RO(revision);
+static ssize_t fw_version_show(struct device *dev, struct device_attribute *attr, char *buf) {
+	struct ithc *ithc = dev_get_drvdata(dev);
+	if (!ithc || !ithc_is_config_valid(ithc)) return -ENODEV;
+	u32 v = ithc->config.fw_version;
+	return sprintf(buf, "%i.%i.%i.%i", v >> 24, v >> 16 & 0xff, v >> 8 & 0xff, v & 0xff);
+}
+static DEVICE_ATTR_RO(fw_version);
+
+static const struct attribute_group *ithc_attribute_groups[] = {
+	&(const struct attribute_group){
+		.name = DEVNAME,
+		.attrs = (struct attribute *[]){
+			&dev_attr_vendor.attr,
+			&dev_attr_product.attr,
+			&dev_attr_revision.attr,
+			&dev_attr_fw_version.attr,
+			NULL
+		},
+	},
+	NULL
+};
+
+// HID setup
+
+static int ithc_hid_start(struct hid_device *hdev) { return 0; }
+static void ithc_hid_stop(struct hid_device *hdev) { }
+static int ithc_hid_open(struct hid_device *hdev) { return 0; }
+static void ithc_hid_close(struct hid_device *hdev) { }
+
+static int ithc_hid_parse(struct hid_device *hdev) {
+	struct ithc *ithc = hdev->driver_data;
+	u64 val = 0;
+	WRITE_ONCE(ithc->hid_parse_done, false);
+	CHECK_RET(ithc_dma_tx, ithc, DMA_TX_CODE_GET_REPORT_DESCRIPTOR, sizeof val, &val);
+	if (!wait_event_timeout(ithc->wait_hid_parse, READ_ONCE(ithc->hid_parse_done), msecs_to_jiffies(1000))) return -ETIMEDOUT;
+	return 0;
+}
+
+static int ithc_hid_raw_request(struct hid_device *hdev, unsigned char reportnum, __u8 *buf, size_t len, unsigned char rtype, int reqtype) {
+	struct ithc *ithc = hdev->driver_data;
+	if (!buf || !len) return -EINVAL;
+	u32 code;
+	if (rtype == HID_OUTPUT_REPORT && reqtype == HID_REQ_SET_REPORT) code = DMA_TX_CODE_OUTPUT_REPORT;
+	else if (rtype == HID_FEATURE_REPORT && reqtype == HID_REQ_SET_REPORT) code = DMA_TX_CODE_SET_FEATURE;
+	else if (rtype == HID_FEATURE_REPORT && reqtype == HID_REQ_GET_REPORT) code = DMA_TX_CODE_GET_FEATURE;
+	else {
+		pci_err(ithc->pci, "unhandled hid request %i %i for report id %i\n", rtype, reqtype, reportnum);
+		return -EINVAL;
+	}
+	buf[0] = reportnum;
+	if (reqtype == HID_REQ_GET_REPORT) {
+		mutex_lock(&ithc->hid_get_feature_mutex);
+		ithc->hid_get_feature_buf = buf;
+		ithc->hid_get_feature_size = len;
+		mutex_unlock(&ithc->hid_get_feature_mutex);
+		int r = CHECK(ithc_dma_tx, ithc, code, 1, buf);
+		if (!r) {
+			r = wait_event_interruptible_timeout(ithc->wait_hid_get_feature, !ithc->hid_get_feature_buf, msecs_to_jiffies(1000));
+			if (!r) r = -ETIMEDOUT;
+			else if (r < 0) r = -EINTR;
+			else r = 0;
+		}
+		mutex_lock(&ithc->hid_get_feature_mutex);
+		ithc->hid_get_feature_buf = NULL;
+		if (!r) r = ithc->hid_get_feature_size;
+		mutex_unlock(&ithc->hid_get_feature_mutex);
+		return r;
+	}
+	CHECK_RET(ithc_dma_tx, ithc, code, len, buf);
+	return 0;
+}
+
+static struct hid_ll_driver ithc_ll_driver = {
+	.start = ithc_hid_start,
+	.stop = ithc_hid_stop,
+	.open = ithc_hid_open,
+	.close = ithc_hid_close,
+	.parse = ithc_hid_parse,
+	.raw_request = ithc_hid_raw_request,
+};
+
+static void ithc_hid_devres_release(struct device *dev, void *res) {
+	struct hid_device **hidm = res;
+	if (*hidm) hid_destroy_device(*hidm);
+}
+
+static int ithc_hid_init(struct ithc *ithc) {
+	struct hid_device **hidm = devres_alloc(ithc_hid_devres_release, sizeof *hidm, GFP_KERNEL);
+	if (!hidm) return -ENOMEM;
+	devres_add(&ithc->pci->dev, hidm);
+	struct hid_device *hid = hid_allocate_device();
+	if (IS_ERR(hid)) return PTR_ERR(hid);
+	*hidm = hid;
+
+	strscpy(hid->name, DEVFULLNAME, sizeof(hid->name));
+	strscpy(hid->phys, ithc->phys, sizeof(hid->phys));
+	hid->ll_driver = &ithc_ll_driver;
+	hid->bus = BUS_PCI;
+	hid->vendor = ithc->config.vendor_id;
+	hid->product = ithc->config.product_id;
+	hid->version = 0x100;
+	hid->dev.parent = &ithc->pci->dev;
+	hid->driver_data = ithc;
+
+	ithc->hid = hid;
+	return 0;
+}
+
+// Interrupts/polling
+
+static void ithc_activity_timer_callback(struct timer_list *t) {
+	struct ithc *ithc = container_of(t, struct ithc, activity_timer);
+	cpu_latency_qos_update_request(&ithc->activity_qos, PM_QOS_DEFAULT_VALUE);
+}
+
+void ithc_set_active(struct ithc *ithc) {
+	// When CPU usage is very low, the CPU can enter various low power states (C2-C10).
+	// This disrupts DMA, causing truncated DMA messages. ERROR_FLAG_DMA_UNKNOWN_12 will be set when this happens.
+	// The amount of truncated messages can become very high, resulting in user-visible effects (laggy/stuttering cursor).
+	// To avoid this, we use a CPU latency QoS request to prevent the CPU from entering low power states during touch interactions.
+	cpu_latency_qos_update_request(&ithc->activity_qos, 0);
+	mod_timer(&ithc->activity_timer, jiffies + msecs_to_jiffies(1000));
+}
+
+static int ithc_set_device_enabled(struct ithc *ithc, bool enable) {
+	u32 x = ithc->config.touch_cfg = (ithc->config.touch_cfg & ~(u32)DEVCFG_TOUCH_MASK) | DEVCFG_TOUCH_UNKNOWN_2
+		| (enable ? DEVCFG_TOUCH_ENABLE | DEVCFG_TOUCH_UNKNOWN_3 | DEVCFG_TOUCH_UNKNOWN_4 : 0);
+	return ithc_spi_command(ithc, SPI_CMD_CODE_WRITE, offsetof(struct ithc_device_config, touch_cfg), sizeof x, &x);
+}
+
+static void ithc_disable_interrupts(struct ithc *ithc) {
+	writel(0, &ithc->regs->error_control);
+	bitsb(&ithc->regs->spi_cmd.control, SPI_CMD_CONTROL_IRQ, 0);
+	bitsb(&ithc->regs->dma_rx[0].control, DMA_RX_CONTROL_IRQ_UNKNOWN_1 | DMA_RX_CONTROL_IRQ_ERROR | DMA_RX_CONTROL_IRQ_UNKNOWN_4 | DMA_RX_CONTROL_IRQ_DATA, 0);
+	bitsb(&ithc->regs->dma_rx[1].control, DMA_RX_CONTROL_IRQ_UNKNOWN_1 | DMA_RX_CONTROL_IRQ_ERROR | DMA_RX_CONTROL_IRQ_UNKNOWN_4 | DMA_RX_CONTROL_IRQ_DATA, 0);
+	bitsb(&ithc->regs->dma_tx.control, DMA_TX_CONTROL_IRQ, 0);
+}
+
+static void ithc_clear_dma_rx_interrupts(struct ithc *ithc, unsigned channel) {
+	writel(DMA_RX_STATUS_ERROR | DMA_RX_STATUS_UNKNOWN_4 | DMA_RX_STATUS_HAVE_DATA, &ithc->regs->dma_rx[channel].status);
+}
+
+static void ithc_clear_interrupts(struct ithc *ithc) {
+	writel(0xffffffff, &ithc->regs->error_flags);
+	writel(ERROR_STATUS_DMA | ERROR_STATUS_SPI, &ithc->regs->error_status);
+	writel(SPI_CMD_STATUS_DONE | SPI_CMD_STATUS_ERROR, &ithc->regs->spi_cmd.status);
+	ithc_clear_dma_rx_interrupts(ithc, 0);
+	ithc_clear_dma_rx_interrupts(ithc, 1);
+	writel(DMA_TX_STATUS_DONE | DMA_TX_STATUS_ERROR | DMA_TX_STATUS_UNKNOWN_2, &ithc->regs->dma_tx.status);
+}
+
+static void ithc_process(struct ithc *ithc) {
+	ithc_log_regs(ithc);
+
+	// read and clear error bits
+	u32 err = readl(&ithc->regs->error_flags);
+	if (err) {
+		if (err & ~ERROR_FLAG_DMA_UNKNOWN_12) pci_err(ithc->pci, "error flags: 0x%08x\n", err);
+		writel(err, &ithc->regs->error_flags);
+	}
+
+	// process DMA rx
+	if (ithc_use_rx0) {
+		ithc_clear_dma_rx_interrupts(ithc, 0);
+		ithc_dma_rx(ithc, 0);
+	}
+	if (ithc_use_rx1) {
+		ithc_clear_dma_rx_interrupts(ithc, 1);
+		ithc_dma_rx(ithc, 1);
+	}
+
+	ithc_log_regs(ithc);
+}
+
+static irqreturn_t ithc_interrupt_thread(int irq, void *arg) {
+	struct ithc *ithc = arg;
+	pci_dbg(ithc->pci, "IRQ! err=%08x/%08x/%08x, cmd=%02x/%08x, rx0=%02x/%08x, rx1=%02x/%08x, tx=%02x/%08x\n",
+		readl(&ithc->regs->error_control), readl(&ithc->regs->error_status), readl(&ithc->regs->error_flags),
+		readb(&ithc->regs->spi_cmd.control), readl(&ithc->regs->spi_cmd.status),
+		readb(&ithc->regs->dma_rx[0].control), readl(&ithc->regs->dma_rx[0].status),
+		readb(&ithc->regs->dma_rx[1].control), readl(&ithc->regs->dma_rx[1].status),
+		readb(&ithc->regs->dma_tx.control), readl(&ithc->regs->dma_tx.status));
+	ithc_process(ithc);
+	return IRQ_HANDLED;
+}
+
+static int ithc_poll_thread(void *arg) {
+	struct ithc *ithc = arg;
+	unsigned sleep = 100;
+	while (!kthread_should_stop()) {
+		u32 n = ithc->dma_rx[1].num_received;
+		ithc_process(ithc);
+		if (n != ithc->dma_rx[1].num_received) sleep = 20;
+		else sleep = min(200u, sleep + (sleep >> 4) + 1);
+		msleep_interruptible(sleep);
+	}
+	return 0;
+}
+
+// Device initialization and shutdown
+
+static void ithc_disable(struct ithc *ithc) {
+	bitsl_set(&ithc->regs->control_bits, CONTROL_QUIESCE);
+	CHECK(waitl, ithc, &ithc->regs->control_bits, CONTROL_IS_QUIESCED, CONTROL_IS_QUIESCED);
+	bitsl(&ithc->regs->control_bits, CONTROL_NRESET, 0);
+	bitsb(&ithc->regs->spi_cmd.control, SPI_CMD_CONTROL_SEND, 0);
+	bitsb(&ithc->regs->dma_tx.control, DMA_TX_CONTROL_SEND, 0);
+	bitsb(&ithc->regs->dma_rx[0].control, DMA_RX_CONTROL_ENABLE, 0);
+	bitsb(&ithc->regs->dma_rx[1].control, DMA_RX_CONTROL_ENABLE, 0);
+	ithc_disable_interrupts(ithc);
+	ithc_clear_interrupts(ithc);
+}
+
+static int ithc_init_device(struct ithc *ithc) {
+	ithc_log_regs(ithc);
+	bool was_enabled = (readl(&ithc->regs->control_bits) & CONTROL_NRESET) != 0;
+	ithc_disable(ithc);
+	CHECK_RET(waitl, ithc, &ithc->regs->control_bits, CONTROL_READY, CONTROL_READY);
+	ithc_set_spi_config(ithc, 10, 0);
+	bitsl_set(&ithc->regs->dma_rx[0].unknown_init_bits, 0x80000000); // seems to help with reading config
+
+	if (was_enabled) if (msleep_interruptible(100)) return -EINTR;
+	bitsl(&ithc->regs->control_bits, CONTROL_QUIESCE, 0);
+	CHECK_RET(waitl, ithc, &ithc->regs->control_bits, CONTROL_IS_QUIESCED, 0);
+	for (int retries = 0; ; retries++) {
+		ithc_log_regs(ithc);
+		bitsl_set(&ithc->regs->control_bits, CONTROL_NRESET);
+		if (!waitl(ithc, &ithc->regs->state, 0xf, 2)) break;
+		if (retries > 5) {
+			pci_err(ithc->pci, "too many retries, failed to reset device\n");
+			return -ETIMEDOUT;
+		}
+		pci_err(ithc->pci, "invalid state, retrying reset\n");
+		bitsl(&ithc->regs->control_bits, CONTROL_NRESET, 0);
+		if (msleep_interruptible(1000)) return -EINTR;
+	}
+	ithc_log_regs(ithc);
+
+	CHECK(waitl, ithc, &ithc->regs->dma_rx[0].status, DMA_RX_STATUS_UNKNOWN_4, DMA_RX_STATUS_UNKNOWN_4);
+
+	// read config
+	for (int retries = 0; ; retries++) {
+		ithc_log_regs(ithc);
+		memset(&ithc->config, 0, sizeof ithc->config);
+		CHECK_RET(ithc_spi_command, ithc, SPI_CMD_CODE_READ, 0, sizeof ithc->config, &ithc->config);
+		u32 *p = (void *)&ithc->config;
+		pci_info(ithc->pci, "config: %08x %08x %08x %08x %08x %08x %08x %08x %08x %08x %08x %08x %08x %08x %08x %08x\n",
+			p[0], p[1], p[2], p[3], p[4], p[5], p[6], p[7], p[8], p[9], p[10], p[11], p[12], p[13], p[14], p[15]);
+		if (ithc_is_config_valid(ithc)) break;
+		if (retries > 10) {
+			pci_err(ithc->pci, "failed to read config, unknown device ID 0x%08x\n", ithc->config.device_id);
+			return -EIO;
+		}
+		pci_err(ithc->pci, "failed to read config, retrying\n");
+		if (msleep_interruptible(100)) return -EINTR;
+	}
+	ithc_log_regs(ithc);
+
+	CHECK_RET(ithc_set_spi_config, ithc, DEVCFG_SPI_MAX_FREQ(ithc->config.spi_config), DEVCFG_SPI_MODE(ithc->config.spi_config));
+	CHECK_RET(ithc_set_device_enabled, ithc, true);
+	ithc_log_regs(ithc);
+	return 0;
+}
+
+int ithc_reset(struct ithc *ithc) {
+	// FIXME This should probably do devres_release_group()+ithc_start(). But because this is called during DMA
+	// processing, that would have to be done asynchronously (schedule_work()?). And with extra locking?
+	pci_err(ithc->pci, "reset\n");
+	CHECK(ithc_init_device, ithc);
+	if (ithc_use_rx0) ithc_dma_rx_enable(ithc, 0);
+	if (ithc_use_rx1) ithc_dma_rx_enable(ithc, 1);
+	ithc_log_regs(ithc);
+	pci_dbg(ithc->pci, "reset completed\n");
+	return 0;
+}
+
+static void ithc_stop(void *res) {
+	struct ithc *ithc = res;
+	pci_dbg(ithc->pci, "stopping\n");
+	ithc_log_regs(ithc);
+	if (ithc->poll_thread) CHECK(kthread_stop, ithc->poll_thread);
+	if (ithc->irq >= 0) disable_irq(ithc->irq);
+	CHECK(ithc_set_device_enabled, ithc, false);
+	ithc_disable(ithc);
+	del_timer_sync(&ithc->activity_timer);
+	cpu_latency_qos_remove_request(&ithc->activity_qos);
+	// clear dma config
+	for(unsigned i = 0; i < 2; i++) {
+		CHECK(waitl, ithc, &ithc->regs->dma_rx[i].status, DMA_RX_STATUS_ENABLED, 0);
+		lo_hi_writeq(0, &ithc->regs->dma_rx[i].addr);
+		writeb(0, &ithc->regs->dma_rx[i].num_bufs);
+		writeb(0, &ithc->regs->dma_rx[i].num_prds);
+	}
+	lo_hi_writeq(0, &ithc->regs->dma_tx.addr);
+	writeb(0, &ithc->regs->dma_tx.num_prds);
+	ithc_log_regs(ithc);
+	pci_dbg(ithc->pci, "stopped\n");
+}
+
+static void ithc_clear_drvdata(void *res) {
+	struct pci_dev *pci = res;
+	pci_set_drvdata(pci, NULL);
+}
+
+static int ithc_start(struct pci_dev *pci) {
+	pci_dbg(pci, "starting\n");
+	if (pci_get_drvdata(pci)) {
+		pci_err(pci, "device already initialized\n");
+		return -EINVAL;
+	}
+	if (!devres_open_group(&pci->dev, ithc_start, GFP_KERNEL)) return -ENOMEM;
+
+	struct ithc *ithc = devm_kzalloc(&pci->dev, sizeof *ithc, GFP_KERNEL);
+	if (!ithc) return -ENOMEM;
+	ithc->irq = -1;
+	ithc->pci = pci;
+	snprintf(ithc->phys, sizeof ithc->phys, "pci-%s/" DEVNAME, pci_name(pci));
+	init_waitqueue_head(&ithc->wait_hid_parse);
+	init_waitqueue_head(&ithc->wait_hid_get_feature);
+	mutex_init(&ithc->hid_get_feature_mutex);
+	pci_set_drvdata(pci, ithc);
+	CHECK_RET(devm_add_action_or_reset, &pci->dev, ithc_clear_drvdata, pci);
+	if (ithc_log_regs_enabled) ithc->prev_regs = devm_kzalloc(&pci->dev, sizeof *ithc->prev_regs, GFP_KERNEL);
+
+	CHECK_RET(pcim_enable_device, pci);
+	pci_set_master(pci);
+	CHECK_RET(pcim_iomap_regions, pci, BIT(0), DEVNAME " regs");
+	CHECK_RET(dma_set_mask_and_coherent, &pci->dev, DMA_BIT_MASK(64));
+	CHECK_RET(pci_set_power_state, pci, PCI_D0);
+	ithc->regs = pcim_iomap_table(pci)[0];
+
+	if (!ithc_use_polling) {
+		CHECK_RET(pci_alloc_irq_vectors, pci, 1, 1, PCI_IRQ_MSI | PCI_IRQ_MSIX);
+		ithc->irq = CHECK(pci_irq_vector, pci, 0);
+		if (ithc->irq < 0) return ithc->irq;
+	}
+
+	CHECK_RET(ithc_init_device, ithc);
+	CHECK(devm_device_add_groups, &pci->dev, ithc_attribute_groups);
+	if (ithc_use_rx0) CHECK_RET(ithc_dma_rx_init, ithc, 0, ithc_use_rx1 ? DEVNAME "0" : DEVNAME);
+	if (ithc_use_rx1) CHECK_RET(ithc_dma_rx_init, ithc, 1, ithc_use_rx0 ? DEVNAME "1" : DEVNAME);
+	CHECK_RET(ithc_dma_tx_init, ithc);
+
+	CHECK_RET(ithc_hid_init, ithc);
+
+	cpu_latency_qos_add_request(&ithc->activity_qos, PM_QOS_DEFAULT_VALUE);
+	timer_setup(&ithc->activity_timer, ithc_activity_timer_callback, 0);
+
+	// add ithc_stop callback AFTER setting up DMA buffers, so that polling/irqs/DMA are disabled BEFORE the buffers are freed
+	CHECK_RET(devm_add_action_or_reset, &pci->dev, ithc_stop, ithc);
+
+	if (ithc_use_polling) {
+		pci_info(pci, "using polling instead of irq\n");
+		// use a thread instead of simple timer because we want to be able to sleep
+		ithc->poll_thread = kthread_run(ithc_poll_thread, ithc, DEVNAME "poll");
+		if (IS_ERR(ithc->poll_thread)) {
+			int err = PTR_ERR(ithc->poll_thread);
+			ithc->poll_thread = NULL;
+			return err;
+		}
+	} else {
+		CHECK_RET(devm_request_threaded_irq, &pci->dev, ithc->irq, NULL, ithc_interrupt_thread, IRQF_TRIGGER_HIGH | IRQF_ONESHOT, DEVNAME, ithc);
+	}
+
+	if (ithc_use_rx0) ithc_dma_rx_enable(ithc, 0);
+	if (ithc_use_rx1) ithc_dma_rx_enable(ithc, 1);
+
+	// hid_add_device can only be called after irq/polling is started and DMA is enabled, because it calls ithc_hid_parse which reads the report descriptor via DMA
+	CHECK_RET(hid_add_device, ithc->hid);
+
+	CHECK(ithc_debug_init, ithc);
+
+	pci_dbg(pci, "started\n");
+	return 0;
+}
+
+static int ithc_probe(struct pci_dev *pci, const struct pci_device_id *id) {
+	pci_dbg(pci, "device probe\n");
+	return ithc_start(pci);
+}
+
+static void ithc_remove(struct pci_dev *pci) {
+	pci_dbg(pci, "device remove\n");
+	// all cleanup is handled by devres
+}
+
+static int ithc_suspend(struct device *dev) {
+	struct pci_dev *pci = to_pci_dev(dev);
+	pci_dbg(pci, "pm suspend\n");
+	devres_release_group(dev, ithc_start);
+	return 0;
+}
+
+static int ithc_resume(struct device *dev) {
+	struct pci_dev *pci = to_pci_dev(dev);
+	pci_dbg(pci, "pm resume\n");
+	return ithc_start(pci);
+}
+
+static int ithc_freeze(struct device *dev) {
+	struct pci_dev *pci = to_pci_dev(dev);
+	pci_dbg(pci, "pm freeze\n");
+	devres_release_group(dev, ithc_start);
+	return 0;
+}
+
+static int ithc_thaw(struct device *dev) {
+	struct pci_dev *pci = to_pci_dev(dev);
+	pci_dbg(pci, "pm thaw\n");
+	return ithc_start(pci);
+}
+
+static int ithc_restore(struct device *dev) {
+	struct pci_dev *pci = to_pci_dev(dev);
+	pci_dbg(pci, "pm restore\n");
+	return ithc_start(pci);
+}
+
+static struct pci_driver ithc_driver = {
+	.name = DEVNAME,
+	.id_table = ithc_pci_tbl,
+	.probe = ithc_probe,
+	.remove = ithc_remove,
+	.driver.pm = &(const struct dev_pm_ops) {
+		.suspend = ithc_suspend,
+		.resume = ithc_resume,
+		.freeze = ithc_freeze,
+		.thaw = ithc_thaw,
+		.restore = ithc_restore,
+	},
+	//.dev_groups = ithc_attribute_groups, // could use this (since 5.14), however the attributes won't have valid values until config has been read anyway
+};
+
+static int __init ithc_init(void) {
+	return pci_register_driver(&ithc_driver);
+}
+
+static void __exit ithc_exit(void) {
+	pci_unregister_driver(&ithc_driver);
+}
+
+module_init(ithc_init);
+module_exit(ithc_exit);
+
diff --git a/drivers/hid/ithc/ithc-regs.c b/drivers/hid/ithc/ithc-regs.c
new file mode 100644
index 000000000000..85d567b05761
--- /dev/null
+++ b/drivers/hid/ithc/ithc-regs.c
@@ -0,0 +1,64 @@
+#include "ithc.h"
+
+#define reg_num(r) (0x1fff & (u16)(__force u64)(r))
+
+void bitsl(__iomem u32 *reg, u32 mask, u32 val) {
+	if (val & ~mask) pr_err("register 0x%x: invalid value 0x%x for bitmask 0x%x\n", reg_num(reg), val, mask);
+	writel((readl(reg) & ~mask) | (val & mask), reg);
+}
+
+void bitsb(__iomem u8 *reg, u8 mask, u8 val) {
+	if (val & ~mask) pr_err("register 0x%x: invalid value 0x%x for bitmask 0x%x\n", reg_num(reg), val, mask);
+	writeb((readb(reg) & ~mask) | (val & mask), reg);
+}
+
+int waitl(struct ithc *ithc, __iomem u32 *reg, u32 mask, u32 val) {
+	pci_dbg(ithc->pci, "waiting for reg 0x%04x mask 0x%08x val 0x%08x\n", reg_num(reg), mask, val);
+	u32 x;
+	if (readl_poll_timeout(reg, x, (x & mask) == val, 200, 1000*1000)) {
+		pci_err(ithc->pci, "timed out waiting for reg 0x%04x mask 0x%08x val 0x%08x\n", reg_num(reg), mask, val);
+		return -ETIMEDOUT;
+	}
+	pci_dbg(ithc->pci, "done waiting\n");
+	return 0;
+}
+
+int waitb(struct ithc *ithc, __iomem u8 *reg, u8 mask, u8 val) {
+	pci_dbg(ithc->pci, "waiting for reg 0x%04x mask 0x%02x val 0x%02x\n", reg_num(reg), mask, val);
+	u8 x;
+	if (readb_poll_timeout(reg, x, (x & mask) == val, 200, 1000*1000)) {
+		pci_err(ithc->pci, "timed out waiting for reg 0x%04x mask 0x%02x val 0x%02x\n", reg_num(reg), mask, val);
+		return -ETIMEDOUT;
+	}
+	pci_dbg(ithc->pci, "done waiting\n");
+	return 0;
+}
+
+int ithc_set_spi_config(struct ithc *ithc, u8 speed, u8 mode) {
+	pci_dbg(ithc->pci, "setting SPI speed to %i, mode %i\n", speed, mode);
+	if (mode == 3) mode = 2;
+	bitsl(&ithc->regs->spi_config,
+		SPI_CONFIG_MODE(0xff) | SPI_CONFIG_SPEED(0xff) | SPI_CONFIG_UNKNOWN_18(0xff) | SPI_CONFIG_SPEED2(0xff),
+		SPI_CONFIG_MODE(mode) | SPI_CONFIG_SPEED(speed) | SPI_CONFIG_UNKNOWN_18(0) | SPI_CONFIG_SPEED2(speed));
+	return 0;
+}
+
+int ithc_spi_command(struct ithc *ithc, u8 command, u32 offset, u32 size, void *data) {
+	pci_dbg(ithc->pci, "SPI command %u, size %u, offset %u\n", command, size, offset);
+	if (size > sizeof ithc->regs->spi_cmd.data) return -EINVAL;
+	CHECK_RET(waitl, ithc, &ithc->regs->spi_cmd.status, SPI_CMD_STATUS_BUSY, 0);
+	writel(SPI_CMD_STATUS_DONE | SPI_CMD_STATUS_ERROR, &ithc->regs->spi_cmd.status);
+	writeb(command, &ithc->regs->spi_cmd.code);
+	writew(size, &ithc->regs->spi_cmd.size);
+	writel(offset, &ithc->regs->spi_cmd.offset);
+	u32 *p = data, n = (size + 3) / 4;
+	for (u32 i = 0; i < n; i++) writel(p[i], &ithc->regs->spi_cmd.data[i]);
+	bitsb_set(&ithc->regs->spi_cmd.control, SPI_CMD_CONTROL_SEND);
+	CHECK_RET(waitl, ithc, &ithc->regs->spi_cmd.status, SPI_CMD_STATUS_BUSY, 0);
+	if ((readl(&ithc->regs->spi_cmd.status) & (SPI_CMD_STATUS_DONE | SPI_CMD_STATUS_ERROR)) != SPI_CMD_STATUS_DONE) return -EIO;
+	if (readw(&ithc->regs->spi_cmd.size) != size) return -EMSGSIZE;
+	for (u32 i = 0; i < n; i++) p[i] = readl(&ithc->regs->spi_cmd.data[i]);
+	writel(SPI_CMD_STATUS_DONE | SPI_CMD_STATUS_ERROR, &ithc->regs->spi_cmd.status);
+	return 0;
+}
+
diff --git a/drivers/hid/ithc/ithc-regs.h b/drivers/hid/ithc/ithc-regs.h
new file mode 100644
index 000000000000..1a96092ed7ee
--- /dev/null
+++ b/drivers/hid/ithc/ithc-regs.h
@@ -0,0 +1,186 @@
+#define CONTROL_QUIESCE                     BIT(1)
+#define CONTROL_IS_QUIESCED                 BIT(2)
+#define CONTROL_NRESET                      BIT(3)
+#define CONTROL_READY                       BIT(29)
+
+#define SPI_CONFIG_MODE(x)                  (((x) & 3) << 2)
+#define SPI_CONFIG_SPEED(x)                 (((x) & 7) << 4)
+#define SPI_CONFIG_UNKNOWN_18(x)            (((x) & 3) << 18)
+#define SPI_CONFIG_SPEED2(x)                (((x) & 0xf) << 20) // high bit = high speed mode?
+
+#define ERROR_CONTROL_UNKNOWN_0             BIT(0)
+#define ERROR_CONTROL_DISABLE_DMA           BIT(1) // clears DMA_RX_CONTROL_ENABLE when a DMA error occurs
+#define ERROR_CONTROL_UNKNOWN_2             BIT(2)
+#define ERROR_CONTROL_UNKNOWN_3             BIT(3)
+#define ERROR_CONTROL_IRQ_DMA_UNKNOWN_9     BIT(9)
+#define ERROR_CONTROL_IRQ_DMA_UNKNOWN_10    BIT(10)
+#define ERROR_CONTROL_IRQ_DMA_UNKNOWN_12    BIT(12)
+#define ERROR_CONTROL_IRQ_DMA_UNKNOWN_13    BIT(13)
+#define ERROR_CONTROL_UNKNOWN_16(x)         (((x) & 0xff) << 16) // spi error code irq?
+#define ERROR_CONTROL_SET_DMA_STATUS        BIT(29) // sets DMA_RX_STATUS_ERROR when a DMA error occurs
+
+#define ERROR_STATUS_DMA                    BIT(28)
+#define ERROR_STATUS_SPI                    BIT(30)
+
+#define ERROR_FLAG_DMA_UNKNOWN_9            BIT(9)
+#define ERROR_FLAG_DMA_UNKNOWN_10           BIT(10)
+#define ERROR_FLAG_DMA_UNKNOWN_12           BIT(12) // set when we receive a truncated DMA message
+#define ERROR_FLAG_DMA_UNKNOWN_13           BIT(13)
+#define ERROR_FLAG_SPI_BUS_TURNAROUND       BIT(16)
+#define ERROR_FLAG_SPI_RESPONSE_TIMEOUT     BIT(17)
+#define ERROR_FLAG_SPI_INTRA_PACKET_TIMEOUT BIT(18)
+#define ERROR_FLAG_SPI_INVALID_RESPONSE     BIT(19)
+#define ERROR_FLAG_SPI_HS_RX_TIMEOUT        BIT(20)
+#define ERROR_FLAG_SPI_TOUCH_IC_INIT        BIT(21)
+
+#define SPI_CMD_CONTROL_SEND                BIT(0) // cleared by device when sending is complete
+#define SPI_CMD_CONTROL_IRQ                 BIT(1)
+
+#define SPI_CMD_CODE_READ                   4
+#define SPI_CMD_CODE_WRITE                  6
+
+#define SPI_CMD_STATUS_DONE                 BIT(0)
+#define SPI_CMD_STATUS_ERROR                BIT(1)
+#define SPI_CMD_STATUS_BUSY                 BIT(3)
+
+#define DMA_TX_CONTROL_SEND                 BIT(0) // cleared by device when sending is complete
+#define DMA_TX_CONTROL_IRQ                  BIT(3)
+
+#define DMA_TX_STATUS_DONE                  BIT(0)
+#define DMA_TX_STATUS_ERROR                 BIT(1)
+#define DMA_TX_STATUS_UNKNOWN_2             BIT(2)
+#define DMA_TX_STATUS_UNKNOWN_3             BIT(3) // busy?
+
+#define DMA_RX_CONTROL_ENABLE               BIT(0)
+#define DMA_RX_CONTROL_IRQ_UNKNOWN_1        BIT(1) // rx1 only?
+#define DMA_RX_CONTROL_IRQ_ERROR            BIT(3) // rx1 only?
+#define DMA_RX_CONTROL_IRQ_UNKNOWN_4        BIT(4) // rx0 only?
+#define DMA_RX_CONTROL_IRQ_DATA             BIT(5)
+
+#define DMA_RX_CONTROL2_UNKNOWN_5           BIT(5) // rx0 only?
+#define DMA_RX_CONTROL2_RESET               BIT(7) // resets ringbuffer indices
+
+#define DMA_RX_WRAP_FLAG                    BIT(7)
+
+#define DMA_RX_STATUS_ERROR                 BIT(3)
+#define DMA_RX_STATUS_UNKNOWN_4             BIT(4) // set in rx0 after using CONTROL_NRESET when it becomes possible to read config (can take >100ms)
+#define DMA_RX_STATUS_HAVE_DATA             BIT(5)
+#define DMA_RX_STATUS_ENABLED               BIT(8)
+
+#define COUNTER_RESET                       BIT(31)
+
+struct ithc_registers {
+	/* 0000 */ u32 _unknown_0000[1024];
+	/* 1000 */ u32 _unknown_1000;
+	/* 1004 */ u32 _unknown_1004;
+	/* 1008 */ u32 control_bits;
+	/* 100c */ u32 _unknown_100c;
+	/* 1010 */ u32 spi_config;
+	/* 1014 */ u32 _unknown_1014[3];
+	/* 1020 */ u32 error_control;
+	/* 1024 */ u32 error_status; // write to clear
+	/* 1028 */ u32 error_flags; // write to clear
+	/* 102c */ u32 _unknown_102c[5];
+	struct {
+		/* 1040 */ u8 control;
+		/* 1041 */ u8 code;
+		/* 1042 */ u16 size;
+		/* 1044 */ u32 status; // write to clear
+		/* 1048 */ u32 offset;
+		/* 104c */ u32 data[16];
+		/* 108c */ u32 _unknown_108c;
+	} spi_cmd;
+	struct {
+		/* 1090 */ u64 addr; // cannot be written with writeq(), must use lo_hi_writeq()
+		/* 1098 */ u8 control;
+		/* 1099 */ u8 _unknown_1099;
+		/* 109a */ u8 _unknown_109a;
+		/* 109b */ u8 num_prds;
+		/* 109c */ u32 status; // write to clear
+	} dma_tx;
+	/* 10a0 */ u32 _unknown_10a0[7];
+	/* 10bc */ u32 state; // is 0xe0000402 (dev config val 0) after CONTROL_NRESET, 0xe0000461 after first touch, 0xe0000401 after DMA_RX_CODE_RESET
+	/* 10c0 */ u32 _unknown_10c0[8];
+	/* 10e0 */ u32 _unknown_10e0_counters[3];
+	/* 10ec */ u32 _unknown_10ec[5];
+	struct {
+		/* 1100/1200 */ u64 addr; // cannot be written with writeq(), must use lo_hi_writeq()
+		/* 1108/1208 */ u8 num_bufs;
+		/* 1109/1209 */ u8 num_prds;
+		/* 110a/120a */ u16 _unknown_110a;
+		/* 110c/120c */ u8 control;
+		/* 110d/120d */ u8 head;
+		/* 110e/120e */ u8 tail;
+		/* 110f/120f */ u8 control2;
+		/* 1110/1210 */ u32 status; // write to clear
+		/* 1114/1214 */ u32 _unknown_1114;
+		/* 1118/1218 */ u64 _unknown_1118_guc_addr;
+		/* 1120/1220 */ u32 _unknown_1120_guc;
+		/* 1124/1224 */ u32 _unknown_1124_guc;
+		/* 1128/1228 */ u32 unknown_init_bits; // bit 2 = guc related, bit 3 = rx1 related, bit 4 = guc related
+		/* 112c/122c */ u32 _unknown_112c;
+		/* 1130/1230 */ u64 _unknown_1130_guc_addr;
+		/* 1138/1238 */ u32 _unknown_1138_guc;
+		/* 113c/123c */ u32 _unknown_113c;
+		/* 1140/1240 */ u32 _unknown_1140_guc;
+		/* 1144/1244 */ u32 _unknown_1144[23];
+		/* 11a0/12a0 */ u32 _unknown_11a0_counters[6];
+		/* 11b8/12b8 */ u32 _unknown_11b8[18];
+	} dma_rx[2];
+};
+static_assert(sizeof(struct ithc_registers) == 0x1300);
+
+#define DEVCFG_DMA_RX_SIZE(x)          ((((x) & 0x3fff) + 1) << 6)
+#define DEVCFG_DMA_TX_SIZE(x)          (((((x) >> 14) & 0x3ff) + 1) << 6)
+
+#define DEVCFG_TOUCH_MASK              0x3f
+#define DEVCFG_TOUCH_ENABLE            BIT(0)
+#define DEVCFG_TOUCH_UNKNOWN_1         BIT(1)
+#define DEVCFG_TOUCH_UNKNOWN_2         BIT(2)
+#define DEVCFG_TOUCH_UNKNOWN_3         BIT(3)
+#define DEVCFG_TOUCH_UNKNOWN_4         BIT(4)
+#define DEVCFG_TOUCH_UNKNOWN_5         BIT(5)
+#define DEVCFG_TOUCH_UNKNOWN_6         BIT(6)
+
+#define DEVCFG_DEVICE_ID_TIC           0x43495424 // "$TIC"
+
+#define DEVCFG_SPI_MAX_FREQ(x)         (((x) >> 1) & 0xf) // high bit = use high speed mode?
+#define DEVCFG_SPI_MODE(x)             (((x) >> 6) & 3)
+#define DEVCFG_SPI_UNKNOWN_8(x)        (((x) >> 8) & 0x3f)
+#define DEVCFG_SPI_NEEDS_HEARTBEAT     BIT(20)
+#define DEVCFG_SPI_HEARTBEAT_INTERVAL  (((x) >> 21) & 7)
+#define DEVCFG_SPI_UNKNOWN_25          BIT(25)
+#define DEVCFG_SPI_UNKNOWN_26          BIT(26)
+#define DEVCFG_SPI_UNKNOWN_27          BIT(27)
+#define DEVCFG_SPI_DELAY               (((x) >> 28) & 7)
+#define DEVCFG_SPI_USE_EXT_READ_CFG    BIT(31)
+
+struct ithc_device_config {
+	u32 _unknown_00;      // 00 = 0xe0000402 (0xe0000401 after DMA_RX_CODE_RESET)
+	u32 _unknown_04;      // 04 = 0x00000000
+	u32 dma_buf_sizes;    // 08 = 0x000a00ff
+	u32 touch_cfg;        // 0c = 0x0000001c
+	u32 _unknown_10;      // 10 = 0x0000001c
+	u32 device_id;        // 14 = 0x43495424 = "$TIC"
+	u32 spi_config;       // 18 = 0xfda00a2e
+	u16 vendor_id;        // 1c = 0x045e = Microsoft Corp.
+	u16 product_id;       // 1e = 0x0c1a
+	u32 revision;         // 20 = 0x00000001
+	u32 fw_version;       // 24 = 0x05008a8b = 5.0.138.139
+	u32 _unknown_28;      // 28 = 0x00000000
+	u32 fw_mode;          // 2c = 0x00000000
+	u32 _unknown_30;      // 30 = 0x00000000
+	u32 _unknown_34;      // 34 = 0x0404035e (u8,u8,u8,u8 = version?)
+	u32 _unknown_38;      // 38 = 0x000001c0 (0x000001c1 after DMA_RX_CODE_RESET)
+	u32 _unknown_3c;      // 3c = 0x00000002
+};
+
+void bitsl(__iomem u32 *reg, u32 mask, u32 val);
+void bitsb(__iomem u8 *reg, u8 mask, u8 val);
+#define bitsl_set(reg, x) bitsl(reg, x, x)
+#define bitsb_set(reg, x) bitsb(reg, x, x)
+int waitl(struct ithc *ithc, __iomem u32 *reg, u32 mask, u32 val);
+int waitb(struct ithc *ithc, __iomem u8 *reg, u8 mask, u8 val);
+int ithc_set_spi_config(struct ithc *ithc, u8 speed, u8 mode);
+int ithc_spi_command(struct ithc *ithc, u8 command, u32 offset, u32 size, void *data);
+
diff --git a/drivers/hid/ithc/ithc.h b/drivers/hid/ithc/ithc.h
new file mode 100644
index 000000000000..6a9b0d480bc1
--- /dev/null
+++ b/drivers/hid/ithc/ithc.h
@@ -0,0 +1,60 @@
+#include <linux/module.h>
+#include <linux/input.h>
+#include <linux/hid.h>
+#include <linux/dma-mapping.h>
+#include <linux/highmem.h>
+#include <linux/pci.h>
+#include <linux/io-64-nonatomic-lo-hi.h>
+#include <linux/iopoll.h>
+#include <linux/delay.h>
+#include <linux/kthread.h>
+#include <linux/miscdevice.h>
+#include <linux/debugfs.h>
+#include <linux/poll.h>
+#include <linux/timer.h>
+#include <linux/pm_qos.h>
+
+#define DEVNAME "ithc"
+#define DEVFULLNAME "Intel Touch Host Controller"
+
+#undef pr_fmt
+#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
+
+#define CHECK(fn, ...) ({ int r = fn(__VA_ARGS__); if (r < 0) pci_err(ithc->pci, "%s: %s failed with %i\n", __func__, #fn, r); r; })
+#define CHECK_RET(...) do { int r = CHECK(__VA_ARGS__); if (r < 0) return r; } while(0)
+
+#define NUM_RX_BUF 16
+
+struct ithc;
+
+#include "ithc-regs.h"
+#include "ithc-dma.h"
+
+struct ithc {
+	char phys[32];
+	struct pci_dev *pci;
+	int irq;
+	struct task_struct *poll_thread;
+	struct pm_qos_request activity_qos;
+	struct timer_list activity_timer;
+
+	struct hid_device *hid;
+	bool hid_parse_done;
+	wait_queue_head_t wait_hid_parse;
+	wait_queue_head_t wait_hid_get_feature;
+	struct mutex hid_get_feature_mutex;
+	void *hid_get_feature_buf;
+	size_t hid_get_feature_size;
+
+	struct ithc_registers __iomem *regs;
+	struct ithc_registers *prev_regs; // for debugging
+	struct ithc_device_config config;
+	struct ithc_dma_rx dma_rx[2];
+	struct ithc_dma_tx dma_tx;
+};
+
+int ithc_reset(struct ithc *ithc);
+void ithc_set_active(struct ithc *ithc);
+int ithc_debug_init(struct ithc *ithc);
+void ithc_log_regs(struct ithc *ithc);
+
-- 
2.41.0