[4/5] RFC: bus: 96boards Low-Speed Connector

diff --git a/drivers/bus/96boards-mezzanines/96boards-ls-connector.c b/drivers/bus/96boards-mezzanines/96boards-ls-connector.c
new file mode 100644
index 000000000000..1a012b0cd457
--- /dev/null
+++ b/drivers/bus/96boards-mezzanines/96boards-ls-connector.c
@@ -0,0 +1,307 @@ 
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * 96boards Low-speed Connector driver
+ * (C) 2018 Linus Walleij <linus.walleij@linaro.org>
+ */
+
+#include <linux/init.h>
+#include <linux/sysfs.h>
+#include <linux/platform_device.h>
+#include <linux/of.h>
+#include <linux/of_platform.h>
+#include <linux/i2c.h>
+#include <linux/spi/spi.h>
+#include "96boards-mezzanines.h"
+
+/**
+ * struct mezzanine - daughter boards (mezzanines) data
+ * Having dynamic data here means that we can only plug ONE board
+ * of each type. Stacking two different boards is fine. This
+ * should be fixed using a linked list of mezzanines if we
+ * go for this solution.
+ */
+struct mezzanine {
+	const char *compatible;
+	const char *sysfs_name;
+	struct dev_ext_attribute ext_attr;
+	void * (*populate) (struct lscon *ls);
+	void (*depopulate) (void *data);
+	void *data;
+};
+
+static struct mezzanine mezzanines[] = {
+#if IS_ENABLED(96BOARDS_SECURE96)
+	{
+		.compatible = "96boards,secure96",
+		.sysfs_name = "secure96",
+		.populate = secure96_populate,
+		.depopulate = secure96_depopulate,
+	},
+#endif
+	/* Add any other mezzanines here */
+};
+
+struct gpio_desc *mezzanine_ls_get_gpiod(struct lscon *ls,
+					 enum mezzanine_ls_gpio pin,
+					 const char *consumer_name,
+					 enum gpiod_flags flags)
+{
+	struct gpio_desc *retdesc;
+
+	/*
+	 * TODO: get all the LS GPIOs as an array on probe() then
+	 * the consumers can skip error handling of IS_ERR() descriptors
+	 * and this need only set the consumer name.
+	 */
+	retdesc = devm_gpiod_get_index(ls->dev, NULL, pin, flags);
+	if (!IS_ERR(retdesc) && consumer_name)
+		gpiod_set_consumer_name(retdesc, consumer_name);
+
+	return retdesc;
+}
+EXPORT_SYMBOL_GPL(mezzanine_ls_get_gpiod);
+
+/*
+ * Mezzanine boards will call this to orderly remove their claimed
+ * gpio descriptors, since we acquired them all with devm_gpiod_get()
+ * they will eventually be released once this connector device
+ * disappears if the board do not release them in order.
+ */
+void mezzanine_ls_put_gpiod(struct lscon *ls, struct gpio_desc *gpiod)
+{
+	devm_gpiod_put(ls->dev, gpiod);
+}
+EXPORT_SYMBOL_GPL(mezzanine_ls_put_gpiod);
+
+static ssize_t mezzanine_show(struct device *dev,
+			      struct device_attribute *attr,
+			      char *buf)
+{
+	struct lscon *ls = dev_get_drvdata(dev);
+	struct dev_ext_attribute *d = container_of(attr,
+						   struct dev_ext_attribute,
+						   attr);
+	struct mezzanine *mez = d->var;
+
+	dev_info(ls->dev, "called %s on %s\n", __func__, mez->sysfs_name);
+	return 0;
+}
+
+static ssize_t mezzanine_store(struct device *dev,
+			       struct device_attribute *attr,
+			       const char *buf, size_t count)
+{
+	struct lscon *ls = dev_get_drvdata(dev);
+	struct dev_ext_attribute *d = container_of(attr,
+						   struct dev_ext_attribute,
+						   attr);
+	struct mezzanine *mez = d->var;
+	unsigned long state;
+	int ret;
+
+	dev_info(ls->dev, "called %s on %s\n", __func__, mez->sysfs_name);
+
+	ret = kstrtoul(buf, 0, &state);
+	if (ret)
+		return ret;
+
+	if (state == 1) {
+		void *data;
+
+		/* Already populated */
+		if (mez->data)
+			return count;
+
+		data = mez->populate(ls);
+		if (IS_ERR(data))
+			return PTR_ERR(data);
+		mez->data = data;
+		return count;
+	}
+
+	if (state == 0) {
+		/* Not populated so nothing to do here */
+		if (!mez->data)
+			return count;
+		mez->depopulate(mez->data);
+		mez->data = NULL;
+		return count;
+	}
+
+	return -EINVAL;
+}
+
+/**
+ * This adds one sysfs file per mezzanine board that we support, so they
+ * can be probed and added from userspace.
+ */
+static int lscon_add_sysfs_mezzanines(struct lscon *ls)
+{
+	struct mezzanine *mez;
+	struct dev_ext_attribute *ext_attr;
+	int ret;
+	int i;
+
+	for (i = 0; i < ARRAY_SIZE(mezzanines); i++) {
+		mez = &mezzanines[i];
+		ext_attr = &mez->ext_attr;
+
+		ext_attr->var = mez;
+		ext_attr->attr.attr.name = mez->sysfs_name;
+		ext_attr->attr.attr.mode = VERIFY_OCTAL_PERMISSIONS(0644);
+		ext_attr->attr.show = mezzanine_show;
+		ext_attr->attr.store = mezzanine_store;
+		ret = device_create_file(ls->dev, &ext_attr->attr);
+		if (ret)
+			dev_err(ls->dev, "unable to create sysfs entries\n");
+
+	}
+
+	return 0;
+}
+
+static int lscon_probe_of_mezzanine(struct lscon *ls, struct device_node *np)
+{
+	struct mezzanine *mez;
+	void *data;
+	int i;
+
+	for (i = 0; i < ARRAY_SIZE(mezzanines); i++) {
+		mez = &mezzanines[i];
+		if (of_device_is_compatible(np, mez->compatible)) {
+			dev_info(ls->dev, "found %s\n", mez->compatible);
+			data = mez->populate(ls);
+			if (IS_ERR(data))
+				return PTR_ERR(data);
+			mez->data = data;
+			return 0;
+		}
+	}
+
+	return 0;
+}
+
+static int lscon_probe(struct platform_device *pdev)
+{
+	struct device *dev = &pdev->dev;
+	struct device_node *np = dev->of_node;
+	struct device_node *child;
+	struct spi_controller *spi;
+	struct mezzanine *mez;
+	struct lscon *ls;
+	int ret;
+	int i;
+
+	ls = devm_kzalloc(dev, sizeof(*ls), GFP_KERNEL);
+	if (!ls)
+		return -ENOMEM;
+	ls->dev = dev;
+
+	/* Bridge I2C busses */
+	child = of_parse_phandle(np, "i2c0", 0);
+	if (!child) {
+		dev_err(dev, "no i2c0 phandle\n");
+		return -ENODEV;
+	}
+	ls->i2c0 = of_get_i2c_adapter_by_node(child);
+	if (!ls->i2c0) {
+		dev_err(dev, "no i2c0 adapter, deferring\n");
+		return -EPROBE_DEFER;
+	}
+
+	child = of_parse_phandle(np, "i2c1", 0);
+	if (!child) {
+		dev_err(dev, "no i2c1 phandle\n");
+		ret = -ENODEV;
+		goto out_put_i2c0;
+	}
+	ls->i2c1 = of_get_i2c_adapter_by_node(child);
+	if (!ls->i2c1) {
+		dev_err(dev, "no i2c0 adapter, deferring\n");
+		ret = -EPROBE_DEFER;
+		goto out_put_i2c0;
+	}
+
+	/* Bride SPI bus */
+	child = of_parse_phandle(np, "spi", 0);
+	if (!child) {
+		dev_err(dev, "no spi phandle\n");
+		ret = -ENODEV;
+		goto out_put_i2c1;
+	}
+	spi = of_find_spi_controller_by_node(child);
+	if (!spi) {
+		dev_err(dev, "no spi controller, deferring\n");
+		ret = -EPROBE_DEFER;
+		goto out_put_i2c1;
+	}
+	ls->spi = spi_controller_get(spi);
+	if (!ls->spi) {
+		dev_err(dev, "no spi reference\n");
+		ret = -ENODEV;
+		goto out_put_i2c1;
+	}
+
+	platform_set_drvdata(pdev, ls);
+
+	/* Get the mezzanine boards, stacking possible */
+	for_each_available_child_of_node(np, child)
+		lscon_probe_of_mezzanine(ls, child);
+
+	ret = lscon_add_sysfs_mezzanines(ls);
+	if (ret)
+		goto out_remove_mezzanines;
+
+	return 0;
+
+out_remove_mezzanines:
+	/* Depopulate any populated boards */
+	for (i = 0; i < ARRAY_SIZE(mezzanines); i++) {
+		mez = &mezzanines[i];
+		if (mez->data)
+			mez->depopulate(mez->data);
+		mez->data = NULL;
+	}
+out_put_i2c1:
+	i2c_put_adapter(ls->i2c1);
+out_put_i2c0:
+	i2c_put_adapter(ls->i2c0);
+	return ret;
+}
+
+static int lscon_remove(struct platform_device *pdev)
+{
+	struct lscon *ls = platform_get_drvdata(pdev);
+	struct mezzanine *mez;
+	int i;
+
+	/* Depopulate any populated boards */
+	for (i = 0; i < ARRAY_SIZE(mezzanines); i++) {
+		mez = &mezzanines[i];
+		if (mez->data)
+			mez->depopulate(mez->data);
+		mez->data = NULL;
+	}
+
+	spi_controller_put(ls->spi);
+	i2c_put_adapter(ls->i2c1);
+	i2c_put_adapter(ls->i2c0);
+
+	return 0;
+}
+
+static const struct of_device_id lscon_of_match[] = {
+	{
+		.compatible = "96boards,low-speed-connector",
+	},
+};
+
+static struct platform_driver lscon_driver = {
+	.driver = {
+		.name = "lscon",
+		.of_match_table = of_match_ptr(lscon_of_match),
+	},
+	.probe  = lscon_probe,
+	.remove = lscon_remove,
+};
+builtin_platform_driver(lscon_driver);
diff --git a/drivers/bus/96boards-mezzanines/96boards-mezzanines.h b/drivers/bus/96boards-mezzanines/96boards-mezzanines.h
new file mode 100644
index 000000000000..f6a460766ff3
--- /dev/null
+++ b/drivers/bus/96boards-mezzanines/96boards-mezzanines.h
@@ -0,0 +1,46 @@ 
+// SPDX-License-Identifier: GPL-2.0
+
+#include <linux/of.h>
+#include <linux/i2c.h>
+#include <linux/gpio/consumer.h>
+
+/**
+ * enum mezzanine_ls_gpio - the GPIO lines on the low-speed connector
+ */
+enum mezzanine_ls_gpio {
+	MEZZANINE_LS_GPIO_A = 0,
+	MEZZANINE_LS_GPIO_B,
+	MEZZANINE_LS_GPIO_C,
+	MEZZANINE_LS_GPIO_D,
+	MEZZANINE_LS_GPIO_E,
+	MEZZANINE_LS_GPIO_F,
+	MEZZANINE_LS_GPIO_G,
+	MEZZANINE_LS_GPIO_H,
+	MEZZANINE_LS_GPIO_I,
+	MEZZANINE_LS_GPIO_J,
+	MEZZANINE_LS_GPIO_K,
+	MEZZANINE_LS_GPIO_L,
+};
+
+/**
+ * struct lscon - low speed connector state container
+ * @dev: containing device for this instance
+ */
+struct lscon {
+	struct device *dev;
+	struct i2c_adapter *i2c0;
+	struct i2c_adapter *i2c1;
+	struct spi_controller *spi;
+};
+
+struct gpio_desc *mezzanine_ls_get_gpiod(struct lscon *ls,
+					 enum mezzanine_ls_gpio pin,
+					 const char *consumer_name,
+					 enum gpiod_flags flags);
+void mezzanine_ls_put_gpiod(struct lscon *ls, struct gpio_desc *gpiod);
+
+#if IS_ENABLED(96BOARDS_SECURE96)
+void *secure96_populate(struct lscon *ls);
+void secure96_depopulate(void *data);
+#endif
+/* Add any other mezzanine population calls here */
diff --git a/drivers/bus/96boards-mezzanines/96boards-secure96.c b/drivers/bus/96boards-mezzanines/96boards-secure96.c
new file mode 100644
index 000000000000..6c44a699d2e0
--- /dev/null
+++ b/drivers/bus/96boards-mezzanines/96boards-secure96.c
@@ -0,0 +1,249 @@ 
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * 96boards Secure96 mezzanine board driver
+ * (C) 2018 Linus Walleij <linus.walleij@linaro.org>
+ */
+#include <linux/gpio/consumer.h>
+#include <linux/platform_device.h>
+#include <linux/leds.h>
+#include <linux/i2c.h>
+#include <linux/spi/spi.h>
+#include <linux/sizes.h>
+#include <linux/platform_data/at24.h>
+#include <linux/delay.h>
+
+#include "96boards-mezzanines.h"
+
+struct secure96 {
+	struct device *dev;
+	struct lscon *ls;
+	struct platform_device *leds_device;
+	struct gpio_led *secure96_leds;
+	struct i2c_client *eeprom;
+	struct i2c_client *crypto;
+	struct i2c_client *hash;
+	struct gpio_desc *tpm_reset;
+	struct gpio_desc *tpm_irq;
+	struct spi_device *tpm;
+};
+
+struct secure96_ledinfo {
+	enum mezzanine_ls_gpio pin;
+	const char *ledname;
+};
+
+/*
+ * GPIO-F, G, H and I are connected to LEDs, two red and two green
+ */
+static const struct secure96_ledinfo ledinfos[] = {
+	{
+		.pin = MEZZANINE_LS_GPIO_F,
+		.ledname = "secure96:red:0",
+	},
+	{
+		.pin = MEZZANINE_LS_GPIO_G,
+		.ledname = "secure96:red:1",
+	},
+	{
+		.pin = MEZZANINE_LS_GPIO_H,
+		.ledname = "secure96:green:0",
+	},
+	{
+		.pin = MEZZANINE_LS_GPIO_I,
+		.ledname = "secure96:green:1",
+	},
+};
+
+/*
+ * The On Semiconductor CAT21M01 is 131072bits i.e. 16KB. This should be
+ * mostly compatible to 24c128 so we register that with special pdata so
+ * that we can fill in the GPIO descriptor for write protect.
+ */
+static struct at24_platform_data secure96_eeprom_pdata = {
+	.byte_len = SZ_16K / 8,
+	.page_size = 256,
+	.flags = AT24_FLAG_ADDR16,
+};
+
+static const struct i2c_board_info secure96_eeprom = {
+	I2C_BOARD_INFO("24c128", 0x50),
+	.platform_data  = &secure96_eeprom_pdata,
+};
+
+/* Crypto chip */
+static const struct i2c_board_info secure96_crypto = {
+	I2C_BOARD_INFO("atecc508a", 0x60),
+};
+
+/* SHA hash chip */
+static const struct i2c_board_info secure96_hash = {
+	I2C_BOARD_INFO("atsha204a", 0x64),
+};
+
+/* Infineon SLB9670 TPM 2.0 chip */
+static struct spi_board_info secure96_tpm = {
+	.modalias = "tpm_tis_spi",
+	/* The manual says 22.5MHz for 1.8V supply */
+	.max_speed_hz = 22500000,
+	.chip_select = 0,
+};
+
+void *secure96_populate(struct lscon *ls)
+{
+	struct device *dev = ls->dev;
+	struct secure96 *sec;
+	struct gpio_desc *gpiod;
+	struct gpio_led_platform_data secure96_leds_pdata;
+	int ret;
+	int i;
+
+	/* TODO: create a struct device for secure96? */
+
+	sec = devm_kzalloc(dev, sizeof(*sec), GFP_KERNEL);
+	if (!sec)
+		return ERR_PTR(-ENOMEM);
+	sec->dev = dev;
+	sec->ls = ls;
+
+	sec->secure96_leds = devm_kzalloc(dev,
+			ARRAY_SIZE(ledinfos) * sizeof(*sec->secure96_leds),
+			GFP_KERNEL);
+	if (!sec->secure96_leds)
+		return ERR_PTR(-ENOMEM);
+
+	dev_info(ls->dev, "populate secure96\n");
+
+	/* Populate the four LEDs */
+	for (i = 0; i < ARRAY_SIZE(ledinfos); i++) {
+		const struct secure96_ledinfo *linfo;
+
+		linfo = &ledinfos[i];
+
+		gpiod = mezzanine_ls_get_gpiod(ls, linfo->pin, linfo->ledname,
+					       GPIOD_OUT_LOW);
+		if (IS_ERR(gpiod)) {
+			dev_err(dev, "failed to get GPIO line %d\n",
+				linfo->pin);
+			return ERR_PTR(-ENODEV);
+		}
+		sec->secure96_leds[i].gpiod = gpiod;
+		sec->secure96_leds[i].name = linfo->ledname;
+		/* Heartbeat on first LED */
+		if (i == 0)
+			sec->secure96_leds[i].default_trigger = "heartbeat";
+	}
+
+	secure96_leds_pdata.num_leds = ARRAY_SIZE(ledinfos);
+	secure96_leds_pdata.leds = sec->secure96_leds;
+
+	sec->leds_device = platform_device_register_data(dev,
+					"leds-gpio",
+					PLATFORM_DEVID_AUTO,
+					&secure96_leds_pdata,
+					sizeof(secure96_leds_pdata));
+	if (IS_ERR(sec->leds_device)) {
+		dev_err(dev, "failed to populate LEDs device\n");
+		return ERR_PTR(-ENODEV);
+	}
+
+	/* Populate the three I2C0 devices */
+	gpiod = mezzanine_ls_get_gpiod(ls, MEZZANINE_LS_GPIO_B, "cat21m01-wp",
+				       GPIOD_OUT_HIGH);
+	if (IS_ERR(gpiod))
+		dev_err(dev, "no CAT21M01 write-protect GPIO\n");
+	else
+		secure96_eeprom_pdata.wp_gpiod = gpiod;
+	sec->eeprom = i2c_new_device(ls->i2c0, &secure96_eeprom);
+	if (!sec->eeprom) {
+		dev_err(dev, "failed to populate EEPROM\n");
+		ret = -ENODEV;
+		goto out_unreg_leds;
+	}
+
+	sec->crypto = i2c_new_device(ls->i2c0, &secure96_crypto);
+	if (!sec->eeprom) {
+		dev_err(dev, "failed to populate crypto device\n");
+		ret = -ENODEV;
+		goto out_remove_eeprom;
+	}
+
+	sec->hash = i2c_new_device(ls->i2c0, &secure96_hash);
+	if (!sec->eeprom) {
+		dev_err(dev, "failed to populate hash device\n");
+		ret = -ENODEV;
+		goto out_remove_crypto;
+	}
+
+	/* Populate the SPI TPM device */
+	gpiod = mezzanine_ls_get_gpiod(ls, MEZZANINE_LS_GPIO_D,
+				       "tpm-slb9670-rst",
+				       GPIOD_OUT_LOW);
+	if (IS_ERR(gpiod)) {
+		dev_err(dev, "failed to get TPM RESET\n");
+		ret = -ENODEV;
+		goto out_remove_hash;
+	}
+	udelay(80);
+	/* Deassert RST */
+	gpiod_set_value(gpiod, 1);
+	sec->tpm_reset = gpiod;
+
+	gpiod = mezzanine_ls_get_gpiod(ls, MEZZANINE_LS_GPIO_C,
+				       "tpm-slb9670-irq",
+				       GPIOD_IN);
+	if (IS_ERR(gpiod)) {
+		dev_err(dev, "failed to get TPM IRQ GPIO\n");
+		ret = -ENODEV;
+		goto out_remove_tpm_reset;
+	}
+	sec->tpm_irq = gpiod;
+	secure96_tpm.irq = gpiod_to_irq(gpiod);
+	sec->tpm = spi_new_device(ls->spi, &secure96_tpm);
+	if (!sec->tpm) {
+		dev_err(dev, "failed to populate TPM device\n");
+		ret = -ENODEV;
+		goto out_remove_tpm_irq;
+	}
+
+	return sec;
+
+out_remove_tpm_irq:
+	mezzanine_ls_put_gpiod(ls, sec->tpm_irq);
+out_remove_tpm_reset:
+	mezzanine_ls_put_gpiod(ls, sec->tpm_reset);
+out_remove_hash:
+	i2c_unregister_device(sec->hash);
+out_remove_crypto:
+	i2c_unregister_device(sec->crypto);
+out_remove_eeprom:
+	i2c_unregister_device(sec->eeprom);
+	if (secure96_eeprom_pdata.wp_gpiod)
+		mezzanine_ls_put_gpiod(ls, secure96_eeprom_pdata.wp_gpiod);
+out_unreg_leds:
+	platform_device_unregister(sec->leds_device);
+	for (i = 0; i < ARRAY_SIZE(ledinfos); i++) {
+		mezzanine_ls_put_gpiod(ls, sec->secure96_leds[i].gpiod);
+	};
+	return ERR_PTR(ret);
+}
+EXPORT_SYMBOL_GPL(secure96_populate);
+
+void secure96_depopulate(void *data)
+{
+	struct secure96 *sec = data;
+	int i;
+
+	spi_unregister_device(sec->tpm);
+	mezzanine_ls_put_gpiod(sec->ls, sec->tpm_irq);
+	mezzanine_ls_put_gpiod(sec->ls, sec->tpm_reset);
+	i2c_unregister_device(sec->hash);
+	i2c_unregister_device(sec->crypto);
+	i2c_unregister_device(sec->eeprom);
+	if (secure96_eeprom_pdata.wp_gpiod)
+		mezzanine_ls_put_gpiod(sec->ls, secure96_eeprom_pdata.wp_gpiod);
+	platform_device_unregister(sec->leds_device);
+	for (i = 0; i < ARRAY_SIZE(ledinfos); i++) {
+		mezzanine_ls_put_gpiod(sec->ls, sec->secure96_leds[i].gpiod);
+	};
+}
+EXPORT_SYMBOL_GPL(secure96_depopulate);
diff --git a/drivers/bus/96boards-mezzanines/Kconfig b/drivers/bus/96boards-mezzanines/Kconfig
new file mode 100644
index 000000000000..18f94e9ec0f8
--- /dev/null
+++ b/drivers/bus/96boards-mezzanines/Kconfig
@@ -0,0 +1,36 @@ 
+# SPDX-License-Identifier: GPL-2.0
+#
+# 96boards mezzanine connectors and drivers
+
+menuconfig 96BOARDS_MEZZANINES
+	bool "96boards mezzanine boards"
+
+if 96BOARDS_MEZZANINES
+
+config 96BOARDS_LS_CONNECTOR
+	bool "96boards low speed connector driver"
+	depends on OF
+	depends on I2C
+	depends on SPI_MASTER
+	depends on GPIOLIB
+	help
+	 Driver for the 96boards low speed connector
+
+config 96BOARDS_SECURE96
+	bool "96boards Secure96 board driver"
+	depends on 96BOARDS_LS_CONNECTOR
+	select NEW_LEDS
+	select LEDS_CLASS
+	select LEDS_GPIO
+	select EEPROM_AT24
+	select CRYPTO_HW
+	select CRYPTO_DEV_ATMEL_ECC
+	select HW_RANDOM
+	select TCG_TPM
+	select HW_RANDOM_TPM
+	select TCG_TIS
+	select TCG_TIS_SPI
+	help
+	 Driver for the 96boards Secure96 mezzanine
+
+endif
diff --git a/drivers/bus/96boards-mezzanines/Makefile b/drivers/bus/96boards-mezzanines/Makefile
new file mode 100644
index 000000000000..a6e1f3507672
--- /dev/null
+++ b/drivers/bus/96boards-mezzanines/Makefile
@@ -0,0 +1,6 @@ 
+# SPDX-License-Identifier: GPL-2.0
+#
+# Makefile for the 96boards mezzanines
+#
+obj-$(CONFIG_96BOARDS_LS_CONNECTOR)	+= 96boards-ls-connector.o
+obj-$(CONFIG_96BOARDS_SECURE96)		+= 96boards-secure96.o
diff --git a/drivers/bus/Kconfig b/drivers/bus/Kconfig
index d1c0b60e9326..46f7785f27e9 100644
--- a/drivers/bus/Kconfig
+++ b/drivers/bus/Kconfig
@@ -173,4 +173,6 @@  config DA8XX_MSTPRI
 
 source "drivers/bus/fsl-mc/Kconfig"
 
+source "drivers/bus/96boards-mezzanines/Kconfig"
+
 endmenu
diff --git a/drivers/bus/Makefile b/drivers/bus/Makefile
index b8f036cca7ff..f6d080a63bd7 100644
--- a/drivers/bus/Makefile
+++ b/drivers/bus/Makefile
@@ -29,5 +29,7 @@  obj-$(CONFIG_TI_SYSC)		+= ti-sysc.o
 obj-$(CONFIG_TS_NBUS)		+= ts-nbus.o
 obj-$(CONFIG_UNIPHIER_SYSTEM_BUS)	+= uniphier-system-bus.o
 obj-$(CONFIG_VEXPRESS_CONFIG)	+= vexpress-config.o
-
 obj-$(CONFIG_DA8XX_MSTPRI)	+= da8xx-mstpri.o
+
+# 96boards mezzanines
+obj-$(CONFIG_96BOARDS_MEZZANINES)	+= 96boards-mezzanines/