drivers/firmware/turris-mox-rwtm.c - kernel/msm-5.4 - Gitiles

 // SPDX-License-Identifier: GPL-2.0
 /*
  * Turris Mox rWTM firmware driver
  *
  * Copyright (C) 2019 Marek Behun <marek.behun@nic.cz>
  */

 #include <linux/armada-37xx-rwtm-mailbox.h>
 #include <linux/completion.h>
 #include <linux/dma-mapping.h>
 #include <linux/hw_random.h>
 #include <linux/mailbox_client.h>
 #include <linux/module.h>
 #include <linux/mutex.h>
 #include <linux/of.h>
 #include <linux/platform_device.h>
 #include <linux/slab.h>

 #define DRIVER_NAME		"turris-mox-rwtm"

 /*
  * The macros and constants below come from Turris Mox's rWTM firmware code.
  * This firmware is open source and it's sources can be found at
  * https://gitlab.labs.nic.cz/turris/mox-boot-builder/tree/master/wtmi.
  */

 #define MBOX_STS_SUCCESS	(0 << 30)
 #define MBOX_STS_FAIL		(1 << 30)
 #define MBOX_STS_BADCMD		(2 << 30)
 #define MBOX_STS_ERROR(s)	((s) & (3 << 30))
 #define MBOX_STS_VALUE(s)	(((s) >> 10) & 0xfffff)
 #define MBOX_STS_CMD(s)		((s) & 0x3ff)

 enum mbox_cmd {
 	MBOX_CMD_GET_RANDOM	= 1,
 	MBOX_CMD_BOARD_INFO	= 2,
 	MBOX_CMD_ECDSA_PUB_KEY	= 3,
 	MBOX_CMD_HASH		= 4,
 	MBOX_CMD_SIGN		= 5,
 	MBOX_CMD_VERIFY		= 6,

 	MBOX_CMD_OTP_READ	= 7,
 	MBOX_CMD_OTP_WRITE	= 8,
 };

 struct mox_kobject;

 struct mox_rwtm {
 	struct device *dev;
 	struct mbox_client mbox_client;
 	struct mbox_chan *mbox;
 	struct mox_kobject *kobj;
 	struct hwrng hwrng;

 	struct armada_37xx_rwtm_rx_msg reply;

 	void *buf;
 	dma_addr_t buf_phys;

 	struct mutex busy;
 	struct completion cmd_done;

 	/* board information */
 	int has_board_info;
 	u64 serial_number;
 	int board_version, ram_size;
 	u8 mac_address1[6], mac_address2[6];

 	/* public key burned in eFuse */
 	int has_pubkey;
 	u8 pubkey[135];
 };

 struct mox_kobject {
 	struct kobject kobj;
 	struct mox_rwtm *rwtm;
 };

 static inline struct kobject *rwtm_to_kobj(struct mox_rwtm *rwtm)
 {
 	return &rwtm->kobj->kobj;
 }

 static inline struct mox_rwtm *to_rwtm(struct kobject *kobj)
 {
 	return container_of(kobj, struct mox_kobject, kobj)->rwtm;
 }

 static void mox_kobj_release(struct kobject *kobj)
 {
 	kfree(to_rwtm(kobj)->kobj);
 }

 static struct kobj_type mox_kobj_ktype = {
 	.release	= mox_kobj_release,
 	.sysfs_ops	= &kobj_sysfs_ops,
 };

 static int mox_kobj_create(struct mox_rwtm *rwtm)
 {
 	rwtm->kobj = kzalloc(sizeof(*rwtm->kobj), GFP_KERNEL);
 	if (!rwtm->kobj)
 		return -ENOMEM;

 	kobject_init(rwtm_to_kobj(rwtm), &mox_kobj_ktype);
 	if (kobject_add(rwtm_to_kobj(rwtm), firmware_kobj, "turris-mox-rwtm")) {
 		kobject_put(rwtm_to_kobj(rwtm));
 		return -ENXIO;
 	}

 	rwtm->kobj->rwtm = rwtm;

 	return 0;
 }

 #define MOX_ATTR_RO(name, format, cat)				\
 static ssize_t							\
 name##_show(struct kobject *kobj, struct kobj_attribute *a,	\
 	    char *buf)						\
 {								\
 	struct mox_rwtm *rwtm = to_rwtm(kobj);	\
 	if (!rwtm->has_##cat)					\
 		return -ENODATA;				\
 	return sprintf(buf, format, rwtm->name);		\
 }								\
 static struct kobj_attribute mox_attr_##name = __ATTR_RO(name)

 MOX_ATTR_RO(serial_number, "%016llX\n", board_info);
 MOX_ATTR_RO(board_version, "%i\n", board_info);
 MOX_ATTR_RO(ram_size, "%i\n", board_info);
 MOX_ATTR_RO(mac_address1, "%pM\n", board_info);
 MOX_ATTR_RO(mac_address2, "%pM\n", board_info);
 MOX_ATTR_RO(pubkey, "%s\n", pubkey);

 static int mox_get_status(enum mbox_cmd cmd, u32 retval)
 {
 	if (MBOX_STS_CMD(retval) != cmd)
 		return -EIO;
 	else if (MBOX_STS_ERROR(retval) == MBOX_STS_FAIL)
 		return -(int)MBOX_STS_VALUE(retval);
 	else if (MBOX_STS_ERROR(retval) == MBOX_STS_BADCMD)
 		return -ENOSYS;
 	else if (MBOX_STS_ERROR(retval) != MBOX_STS_SUCCESS)
 		return -EIO;
 	else
 		return MBOX_STS_VALUE(retval);
 }

 static const struct attribute *mox_rwtm_attrs[] = {
 	&mox_attr_serial_number.attr,
 	&mox_attr_board_version.attr,
 	&mox_attr_ram_size.attr,
 	&mox_attr_mac_address1.attr,
 	&mox_attr_mac_address2.attr,
 	&mox_attr_pubkey.attr,
 	NULL
 };

 static void mox_rwtm_rx_callback(struct mbox_client *cl, void *data)
 {
 	struct mox_rwtm *rwtm = dev_get_drvdata(cl->dev);
 	struct armada_37xx_rwtm_rx_msg *msg = data;

 	rwtm->reply = *msg;
 	complete(&rwtm->cmd_done);
 }

 static void reply_to_mac_addr(u8 *mac, u32 t1, u32 t2)
 {
 	mac[0] = t1 >> 8;
 	mac[1] = t1;
 	mac[2] = t2 >> 24;
 	mac[3] = t2 >> 16;
 	mac[4] = t2 >> 8;
 	mac[5] = t2;
 }

 static int mox_get_board_info(struct mox_rwtm *rwtm)
 {
 	struct armada_37xx_rwtm_tx_msg msg;
 	struct armada_37xx_rwtm_rx_msg *reply = &rwtm->reply;
 	int ret;

 	msg.command = MBOX_CMD_BOARD_INFO;
 	ret = mbox_send_message(rwtm->mbox, &msg);
 	if (ret < 0)
 		return ret;

 	ret = wait_for_completion_timeout(&rwtm->cmd_done, HZ / 2);
 	if (ret < 0)
 		return ret;

 	ret = mox_get_status(MBOX_CMD_BOARD_INFO, reply->retval);
 	if (ret == -ENODATA) {
 		dev_warn(rwtm->dev,
 			 "Board does not have manufacturing information burned!\n");
 	} else if (ret == -ENOSYS) {
 		dev_notice(rwtm->dev,
 			   "Firmware does not support the BOARD_INFO command\n");
 	} else if (ret < 0) {
 		return ret;
 	} else {
 		rwtm->serial_number = reply->status[1];
 		rwtm->serial_number <<= 32;
 		rwtm->serial_number |= reply->status[0];
 			rwtm->board_version = reply->status[2];
 		rwtm->ram_size = reply->status[3];
 		reply_to_mac_addr(rwtm->mac_address1, reply->status[4],
 				  reply->status[5]);
 		reply_to_mac_addr(rwtm->mac_address2, reply->status[6],
 				  reply->status[7]);
 		rwtm->has_board_info = 1;

 		pr_info("Turris Mox serial number %016llX\n",
 			rwtm->serial_number);
 		pr_info("           board version %i\n", rwtm->board_version);
 		pr_info("           burned RAM size %i MiB\n", rwtm->ram_size);
 	}

 	msg.command = MBOX_CMD_ECDSA_PUB_KEY;
 	ret = mbox_send_message(rwtm->mbox, &msg);
 	if (ret < 0)
 		return ret;

 	ret = wait_for_completion_timeout(&rwtm->cmd_done, HZ / 2);
 	if (ret < 0)
 		return ret;

 	ret = mox_get_status(MBOX_CMD_ECDSA_PUB_KEY, reply->retval);
 	if (ret == -ENODATA) {
 		dev_warn(rwtm->dev, "Board has no public key burned!\n");
 	} else if (ret == -ENOSYS) {
 		dev_notice(rwtm->dev,
 			   "Firmware does not support the ECDSA_PUB_KEY command\n");
 	} else if (ret < 0) {
 		return ret;
 	} else {
 		u32 *s = reply->status;

 		rwtm->has_pubkey = 1;
 		sprintf(rwtm->pubkey,
 			"%06x%08x%08x%08x%08x%08x%08x%08x%08x%08x%08x%08x%08x%08x%08x%08x%08x",
 			ret, s[0], s[1], s[2], s[3], s[4], s[5], s[6], s[7],
 			s[8], s[9], s[10], s[11], s[12], s[13], s[14], s[15]);
 	}

 	return 0;
 }

 static int check_get_random_support(struct mox_rwtm *rwtm)
 {
 	struct armada_37xx_rwtm_tx_msg msg;
 	int ret;

 	msg.command = MBOX_CMD_GET_RANDOM;
 	msg.args[0] = 1;
 	msg.args[1] = rwtm->buf_phys;
 	msg.args[2] = 4;

 	ret = mbox_send_message(rwtm->mbox, &msg);
 	if (ret < 0)
 		return ret;

 	ret = wait_for_completion_timeout(&rwtm->cmd_done, HZ / 2);
 	if (ret < 0)
 		return ret;

 	return mox_get_status(MBOX_CMD_GET_RANDOM, rwtm->reply.retval);
 }

 static int mox_hwrng_read(struct hwrng *rng, void *data, size_t max, bool wait)
 {
 	struct mox_rwtm *rwtm = (struct mox_rwtm *) rng->priv;
 	struct armada_37xx_rwtm_tx_msg msg;
 	int ret;

 	if (max > 4096)
 		max = 4096;

 	msg.command = MBOX_CMD_GET_RANDOM;
 	msg.args[0] = 1;
 	msg.args[1] = rwtm->buf_phys;
 	msg.args[2] = (max + 3) & ~3;

 	if (!wait) {
 		if (!mutex_trylock(&rwtm->busy))
 			return -EBUSY;
 	} else {
 		mutex_lock(&rwtm->busy);
 	}

 	ret = mbox_send_message(rwtm->mbox, &msg);
 	if (ret < 0)
 		goto unlock_mutex;

 	ret = wait_for_completion_interruptible(&rwtm->cmd_done);
 	if (ret < 0)
 		goto unlock_mutex;

 	ret = mox_get_status(MBOX_CMD_GET_RANDOM, rwtm->reply.retval);
 	if (ret < 0)
 		goto unlock_mutex;

 	memcpy(data, rwtm->buf, max);
 	ret = max;

 unlock_mutex:
 	mutex_unlock(&rwtm->busy);
 	return ret;
 }

 static int turris_mox_rwtm_probe(struct platform_device *pdev)
 {
 	struct mox_rwtm *rwtm;
 	struct device *dev = &pdev->dev;
 	int ret;

 	rwtm = devm_kzalloc(dev, sizeof(*rwtm), GFP_KERNEL);
 	if (!rwtm)
 		return -ENOMEM;

 	rwtm->dev = dev;
 	rwtm->buf = dmam_alloc_coherent(dev, PAGE_SIZE, &rwtm->buf_phys,
 					GFP_KERNEL);
 	if (!rwtm->buf)
 		return -ENOMEM;

 	ret = mox_kobj_create(rwtm);
 	if (ret < 0) {
 		dev_err(dev, "Cannot create turris-mox-rwtm kobject!\n");
 		return ret;
 	}

 	ret = sysfs_create_files(rwtm_to_kobj(rwtm), mox_rwtm_attrs);
 	if (ret < 0) {
 		dev_err(dev, "Cannot create sysfs files!\n");
 		goto put_kobj;
 	}

 	platform_set_drvdata(pdev, rwtm);

 	mutex_init(&rwtm->busy);

 	rwtm->mbox_client.dev = dev;
 	rwtm->mbox_client.rx_callback = mox_rwtm_rx_callback;

 	rwtm->mbox = mbox_request_channel(&rwtm->mbox_client, 0);
 	if (IS_ERR(rwtm->mbox)) {
 		ret = PTR_ERR(rwtm->mbox);
 		if (ret != -EPROBE_DEFER)
 			dev_err(dev, "Cannot request mailbox channel: %i\n",
 				ret);
 		goto remove_files;
 	}

 	init_completion(&rwtm->cmd_done);

 	ret = mox_get_board_info(rwtm);
 	if (ret < 0)
 		dev_warn(dev, "Cannot read board information: %i\n", ret);

 	ret = check_get_random_support(rwtm);
 	if (ret < 0) {
 		dev_notice(dev,
 			   "Firmware does not support the GET_RANDOM command\n");
 		goto free_channel;
 	}

 	rwtm->hwrng.name = DRIVER_NAME "_hwrng";
 	rwtm->hwrng.read = mox_hwrng_read;
 	rwtm->hwrng.priv = (unsigned long) rwtm;
 	rwtm->hwrng.quality = 1024;

 	ret = devm_hwrng_register(dev, &rwtm->hwrng);
 	if (ret < 0) {
 		dev_err(dev, "Cannot register HWRNG: %i\n", ret);
 		goto free_channel;
 	}

 	return 0;

 free_channel:
 	mbox_free_channel(rwtm->mbox);
 remove_files:
 	sysfs_remove_files(rwtm_to_kobj(rwtm), mox_rwtm_attrs);
 put_kobj:
 	kobject_put(rwtm_to_kobj(rwtm));
 	return ret;
 }

 static int turris_mox_rwtm_remove(struct platform_device *pdev)
 {
 	struct mox_rwtm *rwtm = platform_get_drvdata(pdev);

 	sysfs_remove_files(rwtm_to_kobj(rwtm), mox_rwtm_attrs);
 	kobject_put(rwtm_to_kobj(rwtm));
 	mbox_free_channel(rwtm->mbox);

 	return 0;
 }

 static const struct of_device_id turris_mox_rwtm_match[] = {
 	{ .compatible = "cznic,turris-mox-rwtm", },
 	{ .compatible = "marvell,armada-3700-rwtm-firmware", },
 	{ },
 };

 MODULE_DEVICE_TABLE(of, turris_mox_rwtm_match);

 static struct platform_driver turris_mox_rwtm_driver = {
 	.probe	= turris_mox_rwtm_probe,
 	.remove	= turris_mox_rwtm_remove,
 	.driver	= {
 		.name		= DRIVER_NAME,
 		.of_match_table	= turris_mox_rwtm_match,
 	},
 };
 module_platform_driver(turris_mox_rwtm_driver);

 MODULE_LICENSE("GPL v2");
 MODULE_DESCRIPTION("Turris Mox rWTM firmware driver");
 MODULE_AUTHOR("Marek Behun <marek.behun@nic.cz>");
	// SPDX-License-Identifier: GPL-2.0
	/*
	* Turris Mox rWTM firmware driver
	*
	* Copyright (C) 2019 Marek Behun <marek.behun@nic.cz>
	*/

	#include <linux/armada-37xx-rwtm-mailbox.h>
	#include <linux/completion.h>
	#include <linux/dma-mapping.h>
	#include <linux/hw_random.h>
	#include <linux/mailbox_client.h>
	#include <linux/module.h>
	#include <linux/mutex.h>
	#include <linux/of.h>
	#include <linux/platform_device.h>
	#include <linux/slab.h>

	#define DRIVER_NAME "turris-mox-rwtm"

	/*
	* The macros and constants below come from Turris Mox's rWTM firmware code.
	* This firmware is open source and it's sources can be found at
	* https://gitlab.labs.nic.cz/turris/mox-boot-builder/tree/master/wtmi.
	*/

	#define MBOX_STS_SUCCESS (0 << 30)
	#define MBOX_STS_FAIL (1 << 30)
	#define MBOX_STS_BADCMD (2 << 30)
	#define MBOX_STS_ERROR(s) ((s) & (3 << 30))
	#define MBOX_STS_VALUE(s) (((s) >> 10) & 0xfffff)
	#define MBOX_STS_CMD(s) ((s) & 0x3ff)

	enum mbox_cmd {
	MBOX_CMD_GET_RANDOM = 1,
	MBOX_CMD_BOARD_INFO = 2,
	MBOX_CMD_ECDSA_PUB_KEY = 3,
	MBOX_CMD_HASH = 4,
	MBOX_CMD_SIGN = 5,
	MBOX_CMD_VERIFY = 6,

	MBOX_CMD_OTP_READ = 7,
	MBOX_CMD_OTP_WRITE = 8,
	};

	struct mox_kobject;

	struct mox_rwtm {
	struct device *dev;
	struct mbox_client mbox_client;
	struct mbox_chan *mbox;
	struct mox_kobject *kobj;
	struct hwrng hwrng;

	struct armada_37xx_rwtm_rx_msg reply;

	void *buf;
	dma_addr_t buf_phys;

	struct mutex busy;
	struct completion cmd_done;

	/* board information */
	int has_board_info;
	u64 serial_number;
	int board_version, ram_size;
	u8 mac_address1[6], mac_address2[6];

	/* public key burned in eFuse */
	int has_pubkey;
	u8 pubkey[135];
	};

	struct mox_kobject {
	struct kobject kobj;
	struct mox_rwtm *rwtm;
	};

	static inline struct kobject rwtm_to_kobj(struct mox_rwtm rwtm)
	{
	return &rwtm->kobj->kobj;
	}

	static inline struct mox_rwtm to_rwtm(struct kobject kobj)
	{
	return container_of(kobj, struct mox_kobject, kobj)->rwtm;
	}

	static void mox_kobj_release(struct kobject *kobj)
	{
	kfree(to_rwtm(kobj)->kobj);
	}

	static struct kobj_type mox_kobj_ktype = {
	.release = mox_kobj_release,
	.sysfs_ops = &kobj_sysfs_ops,
	};

	static int mox_kobj_create(struct mox_rwtm *rwtm)
	{
	rwtm->kobj = kzalloc(sizeof(*rwtm->kobj), GFP_KERNEL);
	if (!rwtm->kobj)
	return -ENOMEM;

	kobject_init(rwtm_to_kobj(rwtm), &mox_kobj_ktype);
	if (kobject_add(rwtm_to_kobj(rwtm), firmware_kobj, "turris-mox-rwtm")) {
	kobject_put(rwtm_to_kobj(rwtm));
	return -ENXIO;
	}

	rwtm->kobj->rwtm = rwtm;

	return 0;
	}

	#define MOX_ATTR_RO(name, format, cat) \
	static ssize_t \
	name##_show(struct kobject kobj, struct kobj_attribute a, \
	char *buf) \
	{ \
	struct mox_rwtm *rwtm = to_rwtm(kobj); \
	if (!rwtm->has_##cat) \
	return -ENODATA; \
	return sprintf(buf, format, rwtm->name); \
	} \
	static struct kobj_attribute mox_attr_##name = __ATTR_RO(name)

	MOX_ATTR_RO(serial_number, "%016llX\n", board_info);
	MOX_ATTR_RO(board_version, "%i\n", board_info);
	MOX_ATTR_RO(ram_size, "%i\n", board_info);
	MOX_ATTR_RO(mac_address1, "%pM\n", board_info);
	MOX_ATTR_RO(mac_address2, "%pM\n", board_info);
	MOX_ATTR_RO(pubkey, "%s\n", pubkey);

	static int mox_get_status(enum mbox_cmd cmd, u32 retval)
	{
	if (MBOX_STS_CMD(retval) != cmd)
	return -EIO;
	else if (MBOX_STS_ERROR(retval) == MBOX_STS_FAIL)
	return -(int)MBOX_STS_VALUE(retval);
	else if (MBOX_STS_ERROR(retval) == MBOX_STS_BADCMD)
	return -ENOSYS;
	else if (MBOX_STS_ERROR(retval) != MBOX_STS_SUCCESS)
	return -EIO;
	else
	return MBOX_STS_VALUE(retval);
	}

	static const struct attribute *mox_rwtm_attrs[] = {
	&mox_attr_serial_number.attr,
	&mox_attr_board_version.attr,
	&mox_attr_ram_size.attr,
	&mox_attr_mac_address1.attr,
	&mox_attr_mac_address2.attr,
	&mox_attr_pubkey.attr,
	NULL
	};

	static void mox_rwtm_rx_callback(struct mbox_client cl, void data)
	{
	struct mox_rwtm *rwtm = dev_get_drvdata(cl->dev);
	struct armada_37xx_rwtm_rx_msg *msg = data;

	rwtm->reply = *msg;
	complete(&rwtm->cmd_done);
	}

	static void reply_to_mac_addr(u8 *mac, u32 t1, u32 t2)
	{
	mac[0] = t1 >> 8;
	mac[1] = t1;
	mac[2] = t2 >> 24;
	mac[3] = t2 >> 16;
	mac[4] = t2 >> 8;
	mac[5] = t2;
	}

	static int mox_get_board_info(struct mox_rwtm *rwtm)
	{
	struct armada_37xx_rwtm_tx_msg msg;
	struct armada_37xx_rwtm_rx_msg *reply = &rwtm->reply;
	int ret;

	msg.command = MBOX_CMD_BOARD_INFO;
	ret = mbox_send_message(rwtm->mbox, &msg);
	if (ret < 0)
	return ret;

	ret = wait_for_completion_timeout(&rwtm->cmd_done, HZ / 2);
	if (ret < 0)
	return ret;

	ret = mox_get_status(MBOX_CMD_BOARD_INFO, reply->retval);
	if (ret == -ENODATA) {
	dev_warn(rwtm->dev,
	"Board does not have manufacturing information burned!\n");
	} else if (ret == -ENOSYS) {
	dev_notice(rwtm->dev,
	"Firmware does not support the BOARD_INFO command\n");
	} else if (ret < 0) {
	return ret;
	} else {
	rwtm->serial_number = reply->status[1];
	rwtm->serial_number <<= 32;
	rwtm->serial_number \|= reply->status[0];
	rwtm->board_version = reply->status[2];
	rwtm->ram_size = reply->status[3];
	reply_to_mac_addr(rwtm->mac_address1, reply->status[4],
	reply->status[5]);
	reply_to_mac_addr(rwtm->mac_address2, reply->status[6],
	reply->status[7]);
	rwtm->has_board_info = 1;

	pr_info("Turris Mox serial number %016llX\n",
	rwtm->serial_number);
	pr_info(" board version %i\n", rwtm->board_version);
	pr_info(" burned RAM size %i MiB\n", rwtm->ram_size);
	}

	msg.command = MBOX_CMD_ECDSA_PUB_KEY;
	ret = mbox_send_message(rwtm->mbox, &msg);
	if (ret < 0)
	return ret;

	ret = wait_for_completion_timeout(&rwtm->cmd_done, HZ / 2);
	if (ret < 0)
	return ret;

	ret = mox_get_status(MBOX_CMD_ECDSA_PUB_KEY, reply->retval);
	if (ret == -ENODATA) {
	dev_warn(rwtm->dev, "Board has no public key burned!\n");
	} else if (ret == -ENOSYS) {
	dev_notice(rwtm->dev,
	"Firmware does not support the ECDSA_PUB_KEY command\n");
	} else if (ret < 0) {
	return ret;
	} else {
	u32 *s = reply->status;

	rwtm->has_pubkey = 1;
	sprintf(rwtm->pubkey,
	"%06x%08x%08x%08x%08x%08x%08x%08x%08x%08x%08x%08x%08x%08x%08x%08x%08x",
	ret, s[0], s[1], s[2], s[3], s[4], s[5], s[6], s[7],
	s[8], s[9], s[10], s[11], s[12], s[13], s[14], s[15]);
	}

	return 0;
	}

	static int check_get_random_support(struct mox_rwtm *rwtm)
	{
	struct armada_37xx_rwtm_tx_msg msg;
	int ret;

	msg.command = MBOX_CMD_GET_RANDOM;
	msg.args[0] = 1;
	msg.args[1] = rwtm->buf_phys;
	msg.args[2] = 4;

	ret = mbox_send_message(rwtm->mbox, &msg);
	if (ret < 0)
	return ret;

	ret = wait_for_completion_timeout(&rwtm->cmd_done, HZ / 2);
	if (ret < 0)
	return ret;

	return mox_get_status(MBOX_CMD_GET_RANDOM, rwtm->reply.retval);
	}

	static int mox_hwrng_read(struct hwrng rng, void data, size_t max, bool wait)
	{
	struct mox_rwtm rwtm = (struct mox_rwtm ) rng->priv;
	struct armada_37xx_rwtm_tx_msg msg;
	int ret;

	if (max > 4096)
	max = 4096;

	msg.command = MBOX_CMD_GET_RANDOM;
	msg.args[0] = 1;
	msg.args[1] = rwtm->buf_phys;
	msg.args[2] = (max + 3) & ~3;

	if (!wait) {
	if (!mutex_trylock(&rwtm->busy))
	return -EBUSY;
	} else {
	mutex_lock(&rwtm->busy);
	}

	ret = mbox_send_message(rwtm->mbox, &msg);
	if (ret < 0)
	goto unlock_mutex;

	ret = wait_for_completion_interruptible(&rwtm->cmd_done);
	if (ret < 0)
	goto unlock_mutex;

	ret = mox_get_status(MBOX_CMD_GET_RANDOM, rwtm->reply.retval);
	if (ret < 0)
	goto unlock_mutex;

	memcpy(data, rwtm->buf, max);
	ret = max;

	unlock_mutex:
	mutex_unlock(&rwtm->busy);
	return ret;
	}

	static int turris_mox_rwtm_probe(struct platform_device *pdev)
	{
	struct mox_rwtm *rwtm;
	struct device *dev = &pdev->dev;
	int ret;

	rwtm = devm_kzalloc(dev, sizeof(*rwtm), GFP_KERNEL);
	if (!rwtm)
	return -ENOMEM;

	rwtm->dev = dev;
	rwtm->buf = dmam_alloc_coherent(dev, PAGE_SIZE, &rwtm->buf_phys,
	GFP_KERNEL);
	if (!rwtm->buf)
	return -ENOMEM;

	ret = mox_kobj_create(rwtm);
	if (ret < 0) {
	dev_err(dev, "Cannot create turris-mox-rwtm kobject!\n");
	return ret;
	}

	ret = sysfs_create_files(rwtm_to_kobj(rwtm), mox_rwtm_attrs);
	if (ret < 0) {
	dev_err(dev, "Cannot create sysfs files!\n");
	goto put_kobj;
	}

	platform_set_drvdata(pdev, rwtm);

	mutex_init(&rwtm->busy);

	rwtm->mbox_client.dev = dev;
	rwtm->mbox_client.rx_callback = mox_rwtm_rx_callback;

	rwtm->mbox = mbox_request_channel(&rwtm->mbox_client, 0);
	if (IS_ERR(rwtm->mbox)) {
	ret = PTR_ERR(rwtm->mbox);
	if (ret != -EPROBE_DEFER)
	dev_err(dev, "Cannot request mailbox channel: %i\n",
	ret);
	goto remove_files;
	}

	init_completion(&rwtm->cmd_done);

	ret = mox_get_board_info(rwtm);
	if (ret < 0)
	dev_warn(dev, "Cannot read board information: %i\n", ret);

	ret = check_get_random_support(rwtm);
	if (ret < 0) {
	dev_notice(dev,
	"Firmware does not support the GET_RANDOM command\n");
	goto free_channel;
	}

	rwtm->hwrng.name = DRIVER_NAME "_hwrng";
	rwtm->hwrng.read = mox_hwrng_read;
	rwtm->hwrng.priv = (unsigned long) rwtm;
	rwtm->hwrng.quality = 1024;

	ret = devm_hwrng_register(dev, &rwtm->hwrng);
	if (ret < 0) {
	dev_err(dev, "Cannot register HWRNG: %i\n", ret);
	goto free_channel;
	}

	return 0;

	free_channel:
	mbox_free_channel(rwtm->mbox);
	remove_files:
	sysfs_remove_files(rwtm_to_kobj(rwtm), mox_rwtm_attrs);
	put_kobj:
	kobject_put(rwtm_to_kobj(rwtm));
	return ret;
	}

	static int turris_mox_rwtm_remove(struct platform_device *pdev)
	{
	struct mox_rwtm *rwtm = platform_get_drvdata(pdev);

	sysfs_remove_files(rwtm_to_kobj(rwtm), mox_rwtm_attrs);
	kobject_put(rwtm_to_kobj(rwtm));
	mbox_free_channel(rwtm->mbox);

	return 0;
	}

	static const struct of_device_id turris_mox_rwtm_match[] = {
	{ .compatible = "cznic,turris-mox-rwtm", },
	{ .compatible = "marvell,armada-3700-rwtm-firmware", },
	{ },
	};

	MODULE_DEVICE_TABLE(of, turris_mox_rwtm_match);

	static struct platform_driver turris_mox_rwtm_driver = {
	.probe = turris_mox_rwtm_probe,
	.remove = turris_mox_rwtm_remove,
	.driver = {
	.name = DRIVER_NAME,
	.of_match_table = turris_mox_rwtm_match,
	},
	};
	module_platform_driver(turris_mox_rwtm_driver);

	MODULE_LICENSE("GPL v2");
	MODULE_DESCRIPTION("Turris Mox rWTM firmware driver");
	MODULE_AUTHOR("Marek Behun <marek.behun@nic.cz>");