diff --git a/MAINTAINERS b/MAINTAINERS
index 43b36dbed48e..630ad924d8d5 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -1537,6 +1537,13 @@ F:	drivers/clocksource/timer-atlas7.c
 N:	[^a-z]sirf
 X:	drivers/gnss
 
+ARM/CZ.NIC TURRIS MOX SUPPORT
+M:	Marek Behun <marek.behun@nic.cz>
+W:	http://mox.turris.cz
+S:	Maintained
+F:	include/linux/moxtet.h
+F:	drivers/bus/moxtet.c
+
 ARM/EBSA110 MACHINE SUPPORT
 M:	Russell King <linux@armlinux.org.uk>
 L:	linux-arm-kernel@lists.infradead.org (moderated for non-subscribers)
diff --git a/drivers/bus/Kconfig b/drivers/bus/Kconfig
index 1851112ccc29..6b331061d34b 100644
--- a/drivers/bus/Kconfig
+++ b/drivers/bus/Kconfig
@@ -29,6 +29,16 @@ config BRCMSTB_GISB_ARB
 	  arbiter. This driver provides timeout and target abort error handling
 	  and internal bus master decoding.
 
+config MOXTET
+	tristate "CZ.NIC Turris Mox module configuration bus"
+	depends on SPI_MASTER && OF
+	help
+	  Say yes here to add support for the module configuration bus found
+	  on CZ.NIC's Turris Mox. This is needed for the ability to discover
+	  the order in which the modules are connected and to get/set some of
+	  their settings. For example the GPIOs on Mox SFP module are
+	  configured through this bus.
+
 config HISILICON_LPC
 	bool "Support for ISA I/O space on HiSilicon Hip06/7"
 	depends on ARM64 && (ARCH_HISI || COMPILE_TEST)
diff --git a/drivers/bus/Makefile b/drivers/bus/Makefile
index ca300b1914ce..16b43d3468c6 100644
--- a/drivers/bus/Makefile
+++ b/drivers/bus/Makefile
@@ -8,6 +8,7 @@ obj-$(CONFIG_ARM_CCI)		+= arm-cci.o
 
 obj-$(CONFIG_HISILICON_LPC)	+= hisi_lpc.o
 obj-$(CONFIG_BRCMSTB_GISB_ARB)	+= brcmstb_gisb.o
+obj-$(CONFIG_MOXTET)		+= moxtet.o
 
 # DPAA2 fsl-mc bus
 obj-$(CONFIG_FSL_MC_BUS)	+= fsl-mc/
diff --git a/drivers/bus/moxtet.c b/drivers/bus/moxtet.c
new file mode 100644
index 000000000000..1ee4570e7e17
--- /dev/null
+++ b/drivers/bus/moxtet.c
@@ -0,0 +1,886 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Turris Mox module configuration bus driver
+ *
+ * Copyright (C) 2019 Marek Behun <marek.behun@nic.cz>
+ */
+
+#include <dt-bindings/bus/moxtet.h>
+#include <linux/bitops.h>
+#include <linux/debugfs.h>
+#include <linux/interrupt.h>
+#include <linux/module.h>
+#include <linux/moxtet.h>
+#include <linux/mutex.h>
+#include <linux/of_device.h>
+#include <linux/of_irq.h>
+#include <linux/spi/spi.h>
+
+/*
+ * @name:	module name for sysfs
+ * @hwirq_base:	base index for IRQ for this module (-1 if no IRQs)
+ * @nirqs:	how many interrupts does the shift register provide
+ * @desc:	module description for kernel log
+ */
+static const struct {
+	const char *name;
+	int hwirq_base;
+	int nirqs;
+	const char *desc;
+} mox_module_table[] = {
+	/* do not change order of this array! */
+	{ NULL,		 0,			0, NULL },
+	{ "sfp",	-1,			0, "MOX D (SFP cage)" },
+	{ "pci",	MOXTET_IRQ_PCI,		1, "MOX B (Mini-PCIe)" },
+	{ "topaz",	MOXTET_IRQ_TOPAZ,	1, "MOX C (4 port switch)" },
+	{ "peridot",	MOXTET_IRQ_PERIDOT(0),	1, "MOX E (8 port switch)" },
+	{ "usb3",	MOXTET_IRQ_USB3,	2, "MOX F (USB 3.0)" },
+	{ "pci-bridge",	-1,			0, "MOX G (Mini-PCIe bridge)" },
+};
+
+static inline bool mox_module_known(unsigned int id)
+{
+	return id >= TURRIS_MOX_MODULE_FIRST && id <= TURRIS_MOX_MODULE_LAST;
+}
+
+static inline const char *mox_module_name(unsigned int id)
+{
+	if (mox_module_known(id))
+		return mox_module_table[id].name;
+	else
+		return "unknown";
+}
+
+#define DEF_MODULE_ATTR(name, fmt, ...)					\
+static ssize_t								\
+module_##name##_show(struct device *dev, struct device_attribute *a,	\
+		     char *buf)						\
+{									\
+	struct moxtet_device *mdev = to_moxtet_device(dev);		\
+	return sprintf(buf, (fmt), __VA_ARGS__);			\
+}									\
+static DEVICE_ATTR_RO(module_##name)
+
+DEF_MODULE_ATTR(id, "0x%x\n", mdev->id);
+DEF_MODULE_ATTR(name, "%s\n", mox_module_name(mdev->id));
+DEF_MODULE_ATTR(description, "%s\n",
+		mox_module_known(mdev->id) ? mox_module_table[mdev->id].desc
+					   : "");
+
+static struct attribute *moxtet_dev_attrs[] = {
+	&dev_attr_module_id.attr,
+	&dev_attr_module_name.attr,
+	&dev_attr_module_description.attr,
+	NULL,
+};
+
+static const struct attribute_group moxtet_dev_group = {
+	.attrs = moxtet_dev_attrs,
+};
+
+static const struct attribute_group *moxtet_dev_groups[] = {
+	&moxtet_dev_group,
+	NULL,
+};
+
+static int moxtet_match(struct device *dev, struct device_driver *drv)
+{
+	struct moxtet_device *mdev = to_moxtet_device(dev);
+	struct moxtet_driver *tdrv = to_moxtet_driver(drv);
+	const enum turris_mox_module_id *t;
+
+	if (of_driver_match_device(dev, drv))
+		return 1;
+
+	if (!tdrv->id_table)
+		return 0;
+
+	for (t = tdrv->id_table; *t; ++t)
+		if (*t == mdev->id)
+			return 1;
+
+	return 0;
+}
+
+struct bus_type moxtet_bus_type = {
+	.name		= "moxtet",
+	.dev_groups	= moxtet_dev_groups,
+	.match		= moxtet_match,
+};
+EXPORT_SYMBOL_GPL(moxtet_bus_type);
+
+int __moxtet_register_driver(struct module *owner,
+			     struct moxtet_driver *mdrv)
+{
+	mdrv->driver.owner = owner;
+	mdrv->driver.bus = &moxtet_bus_type;
+	return driver_register(&mdrv->driver);
+}
+EXPORT_SYMBOL_GPL(__moxtet_register_driver);
+
+static int moxtet_dev_check(struct device *dev, void *data)
+{
+	struct moxtet_device *mdev = to_moxtet_device(dev);
+	struct moxtet_device *new_dev = data;
+
+	if (mdev->moxtet == new_dev->moxtet && mdev->id == new_dev->id &&
+	    mdev->idx == new_dev->idx)
+		return -EBUSY;
+	return 0;
+}
+
+static void moxtet_dev_release(struct device *dev)
+{
+	struct moxtet_device *mdev = to_moxtet_device(dev);
+
+	put_device(mdev->moxtet->dev);
+	kfree(mdev);
+}
+
+static struct moxtet_device *
+moxtet_alloc_device(struct moxtet *moxtet)
+{
+	struct moxtet_device *dev;
+
+	if (!get_device(moxtet->dev))
+		return NULL;
+
+	dev = kzalloc(sizeof(*dev), GFP_KERNEL);
+	if (!dev) {
+		put_device(moxtet->dev);
+		return NULL;
+	}
+
+	dev->moxtet = moxtet;
+	dev->dev.parent = moxtet->dev;
+	dev->dev.bus = &moxtet_bus_type;
+	dev->dev.release = moxtet_dev_release;
+
+	device_initialize(&dev->dev);
+
+	return dev;
+}
+
+static int moxtet_add_device(struct moxtet_device *dev)
+{
+	static DEFINE_MUTEX(add_mutex);
+	int ret;
+
+	if (dev->idx >= TURRIS_MOX_MAX_MODULES || dev->id > 0xf)
+		return -EINVAL;
+
+	dev_set_name(&dev->dev, "moxtet-%s.%u", mox_module_name(dev->id),
+		     dev->idx);
+
+	mutex_lock(&add_mutex);
+
+	ret = bus_for_each_dev(&moxtet_bus_type, NULL, dev,
+			       moxtet_dev_check);
+	if (ret)
+		goto done;
+
+	ret = device_add(&dev->dev);
+	if (ret < 0)
+		dev_err(dev->moxtet->dev, "can't add %s, status %d\n",
+			dev_name(dev->moxtet->dev), ret);
+
+done:
+	mutex_unlock(&add_mutex);
+	return ret;
+}
+
+static int __unregister(struct device *dev, void *null)
+{
+	if (dev->of_node) {
+		of_node_clear_flag(dev->of_node, OF_POPULATED);
+		of_node_put(dev->of_node);
+	}
+
+	device_unregister(dev);
+
+	return 0;
+}
+
+static struct moxtet_device *
+of_register_moxtet_device(struct moxtet *moxtet, struct device_node *nc)
+{
+	struct moxtet_device *dev;
+	u32 val;
+	int ret;
+
+	dev = moxtet_alloc_device(moxtet);
+	if (!dev) {
+		dev_err(moxtet->dev,
+			"Moxtet device alloc error for %pOF\n", nc);
+		return ERR_PTR(-ENOMEM);
+	}
+
+	ret = of_property_read_u32(nc, "reg", &val);
+	if (ret) {
+		dev_err(moxtet->dev, "%pOF has no valid 'reg' property (%d)\n",
+			nc, ret);
+		goto err_put;
+	}
+
+	dev->idx = val;
+
+	if (dev->idx >= TURRIS_MOX_MAX_MODULES) {
+		dev_err(moxtet->dev, "%pOF Moxtet address 0x%x out of range\n",
+			nc, dev->idx);
+		ret = -EINVAL;
+		goto err_put;
+	}
+
+	dev->id = moxtet->modules[dev->idx];
+
+	if (!dev->id) {
+		dev_err(moxtet->dev, "%pOF Moxtet address 0x%x is empty\n", nc,
+			dev->idx);
+		ret = -ENODEV;
+		goto err_put;
+	}
+
+	of_node_get(nc);
+	dev->dev.of_node = nc;
+
+	ret = moxtet_add_device(dev);
+	if (ret) {
+		dev_err(moxtet->dev,
+			"Moxtet device register error for %pOF\n", nc);
+		of_node_put(nc);
+		goto err_put;
+	}
+
+	return dev;
+
+err_put:
+	put_device(&dev->dev);
+	return ERR_PTR(ret);
+}
+
+static void of_register_moxtet_devices(struct moxtet *moxtet)
+{
+	struct moxtet_device *dev;
+	struct device_node *nc;
+
+	if (!moxtet->dev->of_node)
+		return;
+
+	for_each_available_child_of_node(moxtet->dev->of_node, nc) {
+		if (of_node_test_and_set_flag(nc, OF_POPULATED))
+			continue;
+		dev = of_register_moxtet_device(moxtet, nc);
+		if (IS_ERR(dev)) {
+			dev_warn(moxtet->dev,
+				 "Failed to create Moxtet device for %pOF\n",
+				 nc);
+			of_node_clear_flag(nc, OF_POPULATED);
+		}
+	}
+}
+
+static void
+moxtet_register_devices_from_topology(struct moxtet *moxtet)
+{
+	struct moxtet_device *dev;
+	int i, ret;
+
+	for (i = 0; i < moxtet->count; ++i) {
+		dev = moxtet_alloc_device(moxtet);
+		if (!dev) {
+			dev_err(moxtet->dev, "Moxtet device %u alloc error\n",
+				i);
+			continue;
+		}
+
+		dev->idx = i;
+		dev->id = moxtet->modules[i];
+
+		ret = moxtet_add_device(dev);
+		if (ret && ret != -EBUSY) {
+			put_device(&dev->dev);
+			dev_err(moxtet->dev,
+				"Moxtet device %u register error: %i\n", i,
+				ret);
+		}
+	}
+}
+
+/*
+ * @nsame:	how many modules with same id are already in moxtet->modules
+ */
+static int moxtet_set_irq(struct moxtet *moxtet, int idx, int id, int nsame)
+{
+	int i, first;
+	struct moxtet_irqpos *pos;
+
+	first = mox_module_table[id].hwirq_base +
+		nsame * mox_module_table[id].nirqs;
+
+	if (first + mox_module_table[id].nirqs > MOXTET_NIRQS)
+		return -EINVAL;
+
+	for (i = 0; i < mox_module_table[id].nirqs; ++i) {
+		pos = &moxtet->irq.position[first + i];
+		pos->idx = idx;
+		pos->bit = i;
+		moxtet->irq.exists |= BIT(first + i);
+	}
+
+	return 0;
+}
+
+static int moxtet_find_topology(struct moxtet *moxtet)
+{
+	u8 buf[TURRIS_MOX_MAX_MODULES];
+	int cnts[TURRIS_MOX_MODULE_LAST];
+	int i, ret;
+
+	memset(cnts, 0, sizeof(cnts));
+
+	ret = spi_read(to_spi_device(moxtet->dev), buf, TURRIS_MOX_MAX_MODULES);
+	if (ret < 0)
+		return ret;
+
+	if (buf[0] == TURRIS_MOX_CPU_ID_EMMC) {
+		dev_info(moxtet->dev, "Found MOX A (eMMC CPU) module\n");
+	} else if (buf[0] == TURRIS_MOX_CPU_ID_SD) {
+		dev_info(moxtet->dev, "Found MOX A (CPU) module\n");
+	} else {
+		dev_err(moxtet->dev, "Invalid Turris MOX A CPU module 0x%02x\n",
+			buf[0]);
+		return -ENODEV;
+	}
+
+	moxtet->count = 0;
+
+	for (i = 1; i < TURRIS_MOX_MAX_MODULES; ++i) {
+		int id;
+
+		if (buf[i] == 0xff)
+			break;
+
+		id = buf[i] & 0xf;
+
+		moxtet->modules[i-1] = id;
+		++moxtet->count;
+
+		if (mox_module_known(id)) {
+			dev_info(moxtet->dev, "Found %s module\n",
+				 mox_module_table[id].desc);
+
+			if (moxtet_set_irq(moxtet, i-1, id, cnts[id]++) < 0)
+				dev_err(moxtet->dev,
+					"  Cannot set IRQ for module %s\n",
+					mox_module_table[id].desc);
+		} else {
+			dev_warn(moxtet->dev,
+				 "Unknown Moxtet module found (ID 0x%02x)\n",
+				 id);
+		}
+	}
+
+	return 0;
+}
+
+static int moxtet_spi_read(struct moxtet *moxtet, u8 *buf)
+{
+	struct spi_transfer xfer = {
+		.rx_buf = buf,
+		.tx_buf = moxtet->tx,
+		.len = moxtet->count + 1
+	};
+	int ret;
+
+	mutex_lock(&moxtet->lock);
+
+	ret = spi_sync_transfer(to_spi_device(moxtet->dev), &xfer, 1);
+
+	mutex_unlock(&moxtet->lock);
+
+	return ret;
+}
+
+int moxtet_device_read(struct device *dev)
+{
+	struct moxtet_device *mdev = to_moxtet_device(dev);
+	struct moxtet *moxtet = mdev->moxtet;
+	u8 buf[TURRIS_MOX_MAX_MODULES];
+	int ret;
+
+	if (mdev->idx >= moxtet->count)
+		return -EINVAL;
+
+	ret = moxtet_spi_read(moxtet, buf);
+	if (ret < 0)
+		return ret;
+
+	return buf[mdev->idx + 1] >> 4;
+}
+EXPORT_SYMBOL_GPL(moxtet_device_read);
+
+int moxtet_device_write(struct device *dev, u8 val)
+{
+	struct moxtet_device *mdev = to_moxtet_device(dev);
+	struct moxtet *moxtet = mdev->moxtet;
+	int ret;
+
+	if (mdev->idx >= moxtet->count)
+		return -EINVAL;
+
+	mutex_lock(&moxtet->lock);
+
+	moxtet->tx[moxtet->count - mdev->idx] = val;
+
+	ret = spi_write(to_spi_device(moxtet->dev), moxtet->tx,
+			moxtet->count + 1);
+
+	mutex_unlock(&moxtet->lock);
+
+	return ret;
+}
+EXPORT_SYMBOL_GPL(moxtet_device_write);
+
+int moxtet_device_written(struct device *dev)
+{
+	struct moxtet_device *mdev = to_moxtet_device(dev);
+	struct moxtet *moxtet = mdev->moxtet;
+
+	if (mdev->idx >= moxtet->count)
+		return -EINVAL;
+
+	return moxtet->tx[moxtet->count - mdev->idx];
+}
+EXPORT_SYMBOL_GPL(moxtet_device_written);
+
+#ifdef CONFIG_DEBUG_FS
+static int moxtet_debug_open(struct inode *inode, struct file *file)
+{
+	file->private_data = inode->i_private;
+
+	return nonseekable_open(inode, file);
+}
+
+static ssize_t input_read(struct file *file, char __user *buf, size_t len,
+			  loff_t *ppos)
+{
+	struct moxtet *moxtet = file->private_data;
+	u8 bin[TURRIS_MOX_MAX_MODULES];
+	u8 hex[sizeof(buf) * 2 + 1];
+	int ret, n;
+
+	ret = moxtet_spi_read(moxtet, bin);
+	if (ret < 0)
+		return ret;
+
+	n = moxtet->count + 1;
+	bin2hex(hex, bin, n);
+
+	hex[2*n] = '\n';
+
+	return simple_read_from_buffer(buf, len, ppos, hex, 2*n + 1);
+}
+
+static const struct file_operations input_fops = {
+	.owner	= THIS_MODULE,
+	.open	= moxtet_debug_open,
+	.read	= input_read,
+	.llseek	= no_llseek,
+};
+
+static ssize_t output_read(struct file *file, char __user *buf, size_t len,
+			   loff_t *ppos)
+{
+	struct moxtet *moxtet = file->private_data;
+	u8 hex[TURRIS_MOX_MAX_MODULES * 2 + 1];
+	u8 *p = hex;
+	int i;
+
+	mutex_lock(&moxtet->lock);
+
+	for (i = 0; i < moxtet->count; ++i)
+		p = hex_byte_pack(p, moxtet->tx[moxtet->count - i]);
+
+	mutex_unlock(&moxtet->lock);
+
+	*p++ = '\n';
+
+	return simple_read_from_buffer(buf, len, ppos, hex, p - hex);
+}
+
+static ssize_t output_write(struct file *file, const char __user *buf,
+			    size_t len, loff_t *ppos)
+{
+	struct moxtet *moxtet = file->private_data;
+	u8 bin[TURRIS_MOX_MAX_MODULES];
+	u8 hex[sizeof(bin) * 2 + 1];
+	size_t res;
+	loff_t dummy = 0;
+	int err, i;
+
+	if (len > 2 * moxtet->count + 1 || len < 2 * moxtet->count)
+		return -EINVAL;
+
+	res = simple_write_to_buffer(hex, sizeof(hex), &dummy, buf, len);
+	if (res < 0)
+		return res;
+
+	if (len % 2 == 1 && hex[len - 1] != '\n')
+		return -EINVAL;
+
+	err = hex2bin(bin, hex, moxtet->count);
+	if (err < 0)
+		return -EINVAL;
+
+	mutex_lock(&moxtet->lock);
+
+	for (i = 0; i < moxtet->count; ++i)
+		moxtet->tx[moxtet->count - i] = bin[i];
+
+	err = spi_write(to_spi_device(moxtet->dev), moxtet->tx,
+			moxtet->count + 1);
+
+	mutex_unlock(&moxtet->lock);
+
+	return err < 0 ? err : len;
+}
+
+static const struct file_operations output_fops = {
+	.owner	= THIS_MODULE,
+	.open	= moxtet_debug_open,
+	.read	= output_read,
+	.write	= output_write,
+	.llseek	= no_llseek,
+};
+
+static int moxtet_register_debugfs(struct moxtet *moxtet)
+{
+	struct dentry *root, *entry;
+
+	root = debugfs_create_dir("moxtet", NULL);
+
+	if (IS_ERR(root))
+		return PTR_ERR(root);
+
+	entry = debugfs_create_file_unsafe("input", 0444, root, moxtet,
+					   &input_fops);
+	if (IS_ERR(entry))
+		goto err_remove;
+
+	entry = debugfs_create_file_unsafe("output", 0644, root, moxtet,
+					   &output_fops);
+	if (IS_ERR(entry))
+		goto err_remove;
+
+	moxtet->debugfs_root = root;
+
+	return 0;
+err_remove:
+	debugfs_remove_recursive(root);
+	return PTR_ERR(entry);
+}
+
+static void moxtet_unregister_debugfs(struct moxtet *moxtet)
+{
+	debugfs_remove_recursive(moxtet->debugfs_root);
+}
+#else
+static inline int moxtet_register_debugfs(struct moxtet *moxtet)
+{
+	return 0;
+}
+
+static inline void moxtet_unregister_debugfs(struct moxtet *moxtet)
+{
+}
+#endif
+
+static int moxtet_irq_domain_map(struct irq_domain *d, unsigned int irq,
+				 irq_hw_number_t hw)
+{
+	struct moxtet *moxtet = d->host_data;
+
+	if (hw >= MOXTET_NIRQS || !(moxtet->irq.exists & BIT(hw))) {
+		dev_err(moxtet->dev, "Invalid hw irq number\n");
+		return -EINVAL;
+	}
+
+	irq_set_chip_data(irq, d->host_data);
+	irq_set_chip_and_handler(irq, &moxtet->irq.chip, handle_level_irq);
+
+	return 0;
+}
+
+static int moxtet_irq_domain_xlate(struct irq_domain *d,
+				   struct device_node *ctrlr,
+				   const u32 *intspec, unsigned int intsize,
+				   unsigned long *out_hwirq,
+				   unsigned int *out_type)
+{
+	struct moxtet *moxtet = d->host_data;
+	int irq;
+
+	if (WARN_ON(intsize < 1))
+		return -EINVAL;
+
+	irq = intspec[0];
+
+	if (irq >= MOXTET_NIRQS || !(moxtet->irq.exists & BIT(irq)))
+		return -EINVAL;
+
+	*out_hwirq = irq;
+	*out_type = IRQ_TYPE_NONE;
+	return 0;
+}
+
+static const struct irq_domain_ops moxtet_irq_domain = {
+	.map = moxtet_irq_domain_map,
+	.xlate = moxtet_irq_domain_xlate,
+};
+
+static void moxtet_irq_mask(struct irq_data *d)
+{
+	struct moxtet *moxtet = irq_data_get_irq_chip_data(d);
+
+	moxtet->irq.masked |= BIT(d->hwirq);
+}
+
+static void moxtet_irq_unmask(struct irq_data *d)
+{
+	struct moxtet *moxtet = irq_data_get_irq_chip_data(d);
+
+	moxtet->irq.masked &= ~BIT(d->hwirq);
+}
+
+static void moxtet_irq_print_chip(struct irq_data *d, struct seq_file *p)
+{
+	struct moxtet *moxtet = irq_data_get_irq_chip_data(d);
+	struct moxtet_irqpos *pos = &moxtet->irq.position[d->hwirq];
+	int id;
+
+	id = moxtet->modules[pos->idx];
+
+	seq_printf(p, " moxtet-%s.%i#%i", mox_module_name(id), pos->idx,
+		   pos->bit);
+}
+
+static const struct irq_chip moxtet_irq_chip = {
+	.name			= "moxtet",
+	.irq_mask		= moxtet_irq_mask,
+	.irq_unmask		= moxtet_irq_unmask,
+	.irq_print_chip		= moxtet_irq_print_chip,
+};
+
+static int moxtet_irq_read(struct moxtet *moxtet, unsigned long *map)
+{
+	struct moxtet_irqpos *pos = moxtet->irq.position;
+	u8 buf[TURRIS_MOX_MAX_MODULES];
+	int i, ret;
+
+	ret = moxtet_spi_read(moxtet, buf);
+	if (ret < 0)
+		return ret;
+
+	*map = 0;
+
+	for_each_set_bit(i, &moxtet->irq.exists, MOXTET_NIRQS) {
+		if (!(buf[pos[i].idx + 1] & BIT(4 + pos[i].bit)))
+			set_bit(i, map);
+	}
+
+	return 0;
+}
+
+static irqreturn_t moxtet_irq_thread_fn(int irq, void *data)
+{
+	struct moxtet *moxtet = data;
+	unsigned long set;
+	int nhandled = 0, i, sub_irq, ret;
+
+	ret = moxtet_irq_read(moxtet, &set);
+	if (ret < 0)
+		goto out;
+
+	set &= ~moxtet->irq.masked;
+
+	do {
+		for_each_set_bit(i, &set, MOXTET_NIRQS) {
+			sub_irq = irq_find_mapping(moxtet->irq.domain, i);
+			handle_nested_irq(sub_irq);
+			dev_dbg(moxtet->dev, "%i irq\n", i);
+			++nhandled;
+		}
+
+		ret = moxtet_irq_read(moxtet, &set);
+		if (ret < 0)
+			goto out;
+
+		set &= ~moxtet->irq.masked;
+	} while (set);
+
+out:
+	return (nhandled > 0 ? IRQ_HANDLED : IRQ_NONE);
+}
+
+static void moxtet_irq_free(struct moxtet *moxtet)
+{
+	int i, irq;
+
+	for (i = 0; i < MOXTET_NIRQS; ++i) {
+		if (moxtet->irq.exists & BIT(i)) {
+			irq = irq_find_mapping(moxtet->irq.domain, i);
+			irq_dispose_mapping(irq);
+		}
+	}
+
+	irq_domain_remove(moxtet->irq.domain);
+}
+
+static int moxtet_irq_setup(struct moxtet *moxtet)
+{
+	int i, ret;
+
+	moxtet->irq.domain = irq_domain_add_simple(moxtet->dev->of_node,
+						   MOXTET_NIRQS, 0,
+						   &moxtet_irq_domain, moxtet);
+	if (moxtet->irq.domain == NULL) {
+		dev_err(moxtet->dev, "Could not add IRQ domain\n");
+		return -ENOMEM;
+	}
+
+	for (i = 0; i < MOXTET_NIRQS; ++i)
+		if (moxtet->irq.exists & BIT(i))
+			irq_create_mapping(moxtet->irq.domain, i);
+
+	moxtet->irq.chip = moxtet_irq_chip;
+	moxtet->irq.masked = ~0;
+
+	ret = request_threaded_irq(moxtet->dev_irq, NULL, moxtet_irq_thread_fn,
+				   IRQF_ONESHOT, "moxtet", moxtet);
+	if (ret < 0)
+		goto err_free;
+
+	return 0;
+
+err_free:
+	moxtet_irq_free(moxtet);
+	return ret;
+}
+
+static int moxtet_probe(struct spi_device *spi)
+{
+	struct moxtet *moxtet;
+	int ret;
+
+	ret = spi_setup(spi);
+	if (ret < 0)
+		return ret;
+
+	moxtet = devm_kzalloc(&spi->dev, sizeof(struct moxtet),
+			      GFP_KERNEL);
+	if (!moxtet)
+		return -ENOMEM;
+
+	moxtet->dev = &spi->dev;
+	spi_set_drvdata(spi, moxtet);
+
+	mutex_init(&moxtet->lock);
+
+	moxtet->dev_irq = of_irq_get(moxtet->dev->of_node, 0);
+	if (moxtet->dev_irq == -EPROBE_DEFER)
+		return -EPROBE_DEFER;
+
+	if (moxtet->dev_irq <= 0) {
+		dev_err(moxtet->dev, "No IRQ resource found\n");
+		return -ENXIO;
+	}
+
+	ret = moxtet_find_topology(moxtet);
+	if (ret < 0)
+		return ret;
+
+	if (moxtet->irq.exists) {
+		ret = moxtet_irq_setup(moxtet);
+		if (ret < 0)
+			return ret;
+	}
+
+	of_register_moxtet_devices(moxtet);
+	moxtet_register_devices_from_topology(moxtet);
+
+	ret = moxtet_register_debugfs(moxtet);
+	if (ret < 0)
+		dev_warn(moxtet->dev, "Failed creating debugfs entries: %i\n",
+			 ret);
+
+	return 0;
+}
+
+static int moxtet_remove(struct spi_device *spi)
+{
+	struct moxtet *moxtet = spi_get_drvdata(spi);
+	int dummy;
+
+	free_irq(moxtet->dev_irq, moxtet);
+
+	moxtet_irq_free(moxtet);
+
+	moxtet_unregister_debugfs(moxtet);
+
+	dummy = device_for_each_child(moxtet->dev, NULL, __unregister);
+
+	mutex_destroy(&moxtet->lock);
+
+	return 0;
+}
+
+static const struct of_device_id moxtet_dt_ids[] = {
+	{ .compatible = "cznic,moxtet" },
+	{},
+};
+MODULE_DEVICE_TABLE(of, moxtet_dt_ids);
+
+static struct spi_driver moxtet_spi_driver = {
+	.driver = {
+		.name		= "moxtet",
+		.of_match_table = moxtet_dt_ids,
+	},
+	.probe		= moxtet_probe,
+	.remove		= moxtet_remove,
+};
+
+static int __init moxtet_init(void)
+{
+	int ret;
+
+	ret = bus_register(&moxtet_bus_type);
+	if (ret < 0) {
+		pr_err("moxtet bus registration failed: %d\n", ret);
+		goto error;
+	}
+
+	ret = spi_register_driver(&moxtet_spi_driver);
+	if (ret < 0) {
+		pr_err("moxtet spi driver registration failed: %d\n", ret);
+		goto error_bus;
+	}
+
+	return 0;
+
+error_bus:
+	bus_unregister(&moxtet_bus_type);
+error:
+	return ret;
+}
+postcore_initcall_sync(moxtet_init);
+
+static void __exit moxtet_exit(void)
+{
+	spi_unregister_driver(&moxtet_spi_driver);
+	bus_unregister(&moxtet_bus_type);
+}
+module_exit(moxtet_exit);
+
+MODULE_AUTHOR("Marek Behun <marek.behun@nic.cz>");
+MODULE_DESCRIPTION("CZ.NIC's Turris Mox module configuration bus");
+MODULE_LICENSE("GPL v2");
diff --git a/include/dt-bindings/bus/moxtet.h b/include/dt-bindings/bus/moxtet.h
new file mode 100644
index 000000000000..dc9345440ebe
--- /dev/null
+++ b/include/dt-bindings/bus/moxtet.h
@@ -0,0 +1,16 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * Constant for device tree bindings for Turris Mox module configuration bus
+ *
+ * Copyright (C) 2019 Marek Behun <marek.behun@nic.cz>
+ */
+
+#ifndef _DT_BINDINGS_BUS_MOXTET_H
+#define _DT_BINDINGS_BUS_MOXTET_H
+
+#define MOXTET_IRQ_PCI		0
+#define MOXTET_IRQ_USB3		4
+#define MOXTET_IRQ_PERIDOT(n)	(8 + (n))
+#define MOXTET_IRQ_TOPAZ	12
+
+#endif /* _DT_BINDINGS_BUS_MOXTET_H */
diff --git a/include/linux/moxtet.h b/include/linux/moxtet.h
new file mode 100644
index 000000000000..490db6886dcc
--- /dev/null
+++ b/include/linux/moxtet.h
@@ -0,0 +1,109 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * Turris Mox module configuration bus driver
+ *
+ * Copyright (C) 2019 Marek Behun <marek.behun@nic.cz>
+ */
+
+#ifndef __LINUX_MOXTET_H
+#define __LINUX_MOXTET_H
+
+#include <linux/device.h>
+#include <linux/irq.h>
+#include <linux/irqdomain.h>
+#include <linux/mutex.h>
+
+#define TURRIS_MOX_MAX_MODULES	10
+
+enum turris_mox_cpu_module_id {
+	TURRIS_MOX_CPU_ID_EMMC	= 0x00,
+	TURRIS_MOX_CPU_ID_SD	= 0x10,
+};
+
+enum turris_mox_module_id {
+	TURRIS_MOX_MODULE_FIRST		= 0x01,
+
+	TURRIS_MOX_MODULE_SFP		= 0x01,
+	TURRIS_MOX_MODULE_PCI		= 0x02,
+	TURRIS_MOX_MODULE_TOPAZ		= 0x03,
+	TURRIS_MOX_MODULE_PERIDOT	= 0x04,
+	TURRIS_MOX_MODULE_USB3		= 0x05,
+	TURRIS_MOX_MODULE_PCI_BRIDGE	= 0x06,
+
+	TURRIS_MOX_MODULE_LAST		= 0x06,
+};
+
+#define MOXTET_NIRQS	16
+
+extern struct bus_type moxtet_type;
+
+struct moxtet {
+	struct device			*dev;
+	struct mutex			lock;
+	u8				modules[TURRIS_MOX_MAX_MODULES];
+	int				count;
+	u8				tx[TURRIS_MOX_MAX_MODULES];
+	int				dev_irq;
+	struct {
+		struct irq_domain	*domain;
+		struct irq_chip		chip;
+		unsigned long		masked, exists;
+		struct moxtet_irqpos {
+					u8 idx;
+					u8 bit;
+		} position[MOXTET_NIRQS];
+	} irq;
+#ifdef CONFIG_DEBUG_FS
+	struct dentry			*debugfs_root;
+#endif
+};
+
+struct moxtet_driver {
+	const enum turris_mox_module_id	*id_table;
+	struct device_driver		driver;
+};
+
+static inline struct moxtet_driver *
+to_moxtet_driver(struct device_driver *drv)
+{
+	if (!drv)
+		return NULL;
+	return container_of(drv, struct moxtet_driver, driver);
+}
+
+extern int __moxtet_register_driver(struct module *owner,
+				    struct moxtet_driver *mdrv);
+
+static inline void moxtet_unregister_driver(struct moxtet_driver *mdrv)
+{
+	if (mdrv)
+		driver_unregister(&mdrv->driver);
+}
+
+#define moxtet_register_driver(driver) \
+	__moxtet_register_driver(THIS_MODULE, driver)
+
+#define module_moxtet_driver(__moxtet_driver) \
+	module_driver(__moxtet_driver, moxtet_register_driver, \
+			moxtet_unregister_driver)
+
+struct moxtet_device {
+	struct device			dev;
+	struct moxtet			*moxtet;
+	enum turris_mox_module_id	id;
+	unsigned int			idx;
+};
+
+extern int moxtet_device_read(struct device *dev);
+extern int moxtet_device_write(struct device *dev, u8 val);
+extern int moxtet_device_written(struct device *dev);
+
+static inline struct moxtet_device *
+to_moxtet_device(struct device *dev)
+{
+	if (!dev)
+		return NULL;
+	return container_of(dev, struct moxtet_device, dev);
+}
+
+#endif /* __LINUX_MOXTET_H */
