ARK-OS/arkos/kernel/drivers/greybus/svc.c

// SPDX-License-Identifier: GPL-2.0
/*
 * SVC Greybus driver.
 *
 * Copyright 2015 Google Inc.
 * Copyright 2015 Linaro Ltd.
 */

#include <linux/debugfs.h>
#include <linux/kstrtox.h>
#include <linux/workqueue.h>
#include <linux/greybus.h>
#include <linux/string_choices.h>

#define SVC_INTF_EJECT_TIMEOUT		9000
#define SVC_INTF_ACTIVATE_TIMEOUT	6000
#define SVC_INTF_RESUME_TIMEOUT		3000

struct gb_svc_deferred_request {
	struct work_struct work;
	struct gb_operation *operation;
};

static int gb_svc_queue_deferred_request(struct gb_operation *operation);

static ssize_t endo_id_show(struct device *dev,
			    struct device_attribute *attr, char *buf)
{
	struct gb_svc *svc = to_gb_svc(dev);

	return sprintf(buf, "0x%04x\n", svc->endo_id);
}
static DEVICE_ATTR_RO(endo_id);

static ssize_t ap_intf_id_show(struct device *dev,
			       struct device_attribute *attr, char *buf)
{
	struct gb_svc *svc = to_gb_svc(dev);

	return sprintf(buf, "%u\n", svc->ap_intf_id);
}
static DEVICE_ATTR_RO(ap_intf_id);

// FIXME
// This is a hack, we need to do this "right" and clean the interface up
// properly, not just forcibly yank the thing out of the system and hope for the
// best.  But for now, people want their modules to come out without having to
// throw the thing to the ground or get out a screwdriver.
static ssize_t intf_eject_store(struct device *dev,
				struct device_attribute *attr, const char *buf,
				size_t len)
{
	struct gb_svc *svc = to_gb_svc(dev);
	unsigned short intf_id;
	int ret;

	ret = kstrtou16(buf, 10, &intf_id);
	if (ret < 0)
		return ret;

	dev_warn(dev, "Forcibly trying to eject interface %d\n", intf_id);

	ret = gb_svc_intf_eject(svc, intf_id);
	if (ret < 0)
		return ret;

	return len;
}
static DEVICE_ATTR_WO(intf_eject);

static ssize_t watchdog_show(struct device *dev, struct device_attribute *attr,
			     char *buf)
{
	struct gb_svc *svc = to_gb_svc(dev);

	return sprintf(buf, "%s\n",
		       str_enabled_disabled(gb_svc_watchdog_enabled(svc)));
}

static ssize_t watchdog_store(struct device *dev,
			      struct device_attribute *attr, const char *buf,
			      size_t len)
{
	struct gb_svc *svc = to_gb_svc(dev);
	int retval;
	bool user_request;

	retval = kstrtobool(buf, &user_request);
	if (retval)
		return retval;

	if (user_request)
		retval = gb_svc_watchdog_enable(svc);
	else
		retval = gb_svc_watchdog_disable(svc);
	if (retval)
		return retval;
	return len;
}
static DEVICE_ATTR_RW(watchdog);

static ssize_t watchdog_action_show(struct device *dev,
				    struct device_attribute *attr, char *buf)
{
	struct gb_svc *svc = to_gb_svc(dev);

	if (svc->action == GB_SVC_WATCHDOG_BITE_PANIC_KERNEL)
		return sprintf(buf, "panic\n");
	else if (svc->action == GB_SVC_WATCHDOG_BITE_RESET_UNIPRO)
		return sprintf(buf, "reset\n");

	return -EINVAL;
}

static ssize_t watchdog_action_store(struct device *dev,
				     struct device_attribute *attr,
				     const char *buf, size_t len)
{
	struct gb_svc *svc = to_gb_svc(dev);

	if (sysfs_streq(buf, "panic"))
		svc->action = GB_SVC_WATCHDOG_BITE_PANIC_KERNEL;
	else if (sysfs_streq(buf, "reset"))
		svc->action = GB_SVC_WATCHDOG_BITE_RESET_UNIPRO;
	else
		return -EINVAL;

	return len;
}
static DEVICE_ATTR_RW(watchdog_action);

static int gb_svc_pwrmon_rail_count_get(struct gb_svc *svc, u8 *value)
{
	struct gb_svc_pwrmon_rail_count_get_response response;
	int ret;

	ret = gb_operation_sync(svc->connection,
				GB_SVC_TYPE_PWRMON_RAIL_COUNT_GET, NULL, 0,
				&response, sizeof(response));
	if (ret) {
		dev_err(&svc->dev, "failed to get rail count: %d\n", ret);
		return ret;
	}

	*value = response.rail_count;

	return 0;
}

static int gb_svc_pwrmon_rail_names_get(struct gb_svc *svc,
		struct gb_svc_pwrmon_rail_names_get_response *response,
		size_t bufsize)
{
	int ret;

	ret = gb_operation_sync(svc->connection,
				GB_SVC_TYPE_PWRMON_RAIL_NAMES_GET, NULL, 0,
				response, bufsize);
	if (ret) {
		dev_err(&svc->dev, "failed to get rail names: %d\n", ret);
		return ret;
	}

	if (response->status != GB_SVC_OP_SUCCESS) {
		dev_err(&svc->dev,
			"SVC error while getting rail names: %u\n",
			response->status);
		return -EREMOTEIO;
	}

	return 0;
}

static int gb_svc_pwrmon_sample_get(struct gb_svc *svc, u8 rail_id,
				    u8 measurement_type, u32 *value)
{
	struct gb_svc_pwrmon_sample_get_request request;
	struct gb_svc_pwrmon_sample_get_response response;
	int ret;

	request.rail_id = rail_id;
	request.measurement_type = measurement_type;

	ret = gb_operation_sync(svc->connection, GB_SVC_TYPE_PWRMON_SAMPLE_GET,
				&request, sizeof(request),
				&response, sizeof(response));
	if (ret) {
		dev_err(&svc->dev, "failed to get rail sample: %d\n", ret);
		return ret;
	}

	if (response.result) {
		dev_err(&svc->dev,
			"UniPro error while getting rail power sample (%d %d): %d\n",
			rail_id, measurement_type, response.result);
		switch (response.result) {
		case GB_SVC_PWRMON_GET_SAMPLE_INVAL:
			return -EINVAL;
		case GB_SVC_PWRMON_GET_SAMPLE_NOSUPP:
			return -ENOMSG;
		default:
			return -EREMOTEIO;
		}
	}

	*value = le32_to_cpu(response.measurement);

	return 0;
}

int gb_svc_pwrmon_intf_sample_get(struct gb_svc *svc, u8 intf_id,
				  u8 measurement_type, u32 *value)
{
	struct gb_svc_pwrmon_intf_sample_get_request request;
	struct gb_svc_pwrmon_intf_sample_get_response response;
	int ret;

	request.intf_id = intf_id;
	request.measurement_type = measurement_type;

	ret = gb_operation_sync(svc->connection,
				GB_SVC_TYPE_PWRMON_INTF_SAMPLE_GET,
				&request, sizeof(request),
				&response, sizeof(response));
	if (ret) {
		dev_err(&svc->dev, "failed to get intf sample: %d\n", ret);
		return ret;
	}

	if (response.result) {
		dev_err(&svc->dev,
			"UniPro error while getting intf power sample (%d %d): %d\n",
			intf_id, measurement_type, response.result);
		switch (response.result) {
		case GB_SVC_PWRMON_GET_SAMPLE_INVAL:
			return -EINVAL;
		case GB_SVC_PWRMON_GET_SAMPLE_NOSUPP:
			return -ENOMSG;
		default:
			return -EREMOTEIO;
		}
	}

	*value = le32_to_cpu(response.measurement);

	return 0;
}

static struct attribute *svc_attrs[] = {
	&dev_attr_endo_id.attr,
	&dev_attr_ap_intf_id.attr,
	&dev_attr_intf_eject.attr,
	&dev_attr_watchdog.attr,
	&dev_attr_watchdog_action.attr,
	NULL,
};
ATTRIBUTE_GROUPS(svc);

int gb_svc_intf_device_id(struct gb_svc *svc, u8 intf_id, u8 device_id)
{
	struct gb_svc_intf_device_id_request request;

	request.intf_id = intf_id;
	request.device_id = device_id;

	return gb_operation_sync(svc->connection, GB_SVC_TYPE_INTF_DEVICE_ID,
				 &request, sizeof(request), NULL, 0);
}

int gb_svc_intf_eject(struct gb_svc *svc, u8 intf_id)
{
	struct gb_svc_intf_eject_request request;
	int ret;

	request.intf_id = intf_id;

	/*
	 * The pulse width for module release in svc is long so we need to
	 * increase the timeout so the operation will not return to soon.
	 */
	ret = gb_operation_sync_timeout(svc->connection,
					GB_SVC_TYPE_INTF_EJECT, &request,
					sizeof(request), NULL, 0,
					SVC_INTF_EJECT_TIMEOUT);
	if (ret) {
		dev_err(&svc->dev, "failed to eject interface %u\n", intf_id);
		return ret;
	}

	return 0;
}

int gb_svc_intf_vsys_set(struct gb_svc *svc, u8 intf_id, bool enable)
{
	struct gb_svc_intf_vsys_request request;
	struct gb_svc_intf_vsys_response response;
	int type, ret;

	request.intf_id = intf_id;

	if (enable)
		type = GB_SVC_TYPE_INTF_VSYS_ENABLE;
	else
		type = GB_SVC_TYPE_INTF_VSYS_DISABLE;

	ret = gb_operation_sync(svc->connection, type,
				&request, sizeof(request),
				&response, sizeof(response));
	if (ret < 0)
		return ret;
	if (response.result_code != GB_SVC_INTF_VSYS_OK)
		return -EREMOTEIO;
	return 0;
}

int gb_svc_intf_refclk_set(struct gb_svc *svc, u8 intf_id, bool enable)
{
	struct gb_svc_intf_refclk_request request;
	struct gb_svc_intf_refclk_response response;
	int type, ret;

	request.intf_id = intf_id;

	if (enable)
		type = GB_SVC_TYPE_INTF_REFCLK_ENABLE;
	else
		type = GB_SVC_TYPE_INTF_REFCLK_DISABLE;

	ret = gb_operation_sync(svc->connection, type,
				&request, sizeof(request),
				&response, sizeof(response));
	if (ret < 0)
		return ret;
	if (response.result_code != GB_SVC_INTF_REFCLK_OK)
		return -EREMOTEIO;
	return 0;
}

int gb_svc_intf_unipro_set(struct gb_svc *svc, u8 intf_id, bool enable)
{
	struct gb_svc_intf_unipro_request request;
	struct gb_svc_intf_unipro_response response;
	int type, ret;

	request.intf_id = intf_id;

	if (enable)
		type = GB_SVC_TYPE_INTF_UNIPRO_ENABLE;
	else
		type = GB_SVC_TYPE_INTF_UNIPRO_DISABLE;

	ret = gb_operation_sync(svc->connection, type,
				&request, sizeof(request),
				&response, sizeof(response));
	if (ret < 0)
		return ret;
	if (response.result_code != GB_SVC_INTF_UNIPRO_OK)
		return -EREMOTEIO;
	return 0;
}

int gb_svc_intf_activate(struct gb_svc *svc, u8 intf_id, u8 *intf_type)
{
	struct gb_svc_intf_activate_request request;
	struct gb_svc_intf_activate_response response;
	int ret;

	request.intf_id = intf_id;

	ret = gb_operation_sync_timeout(svc->connection,
					GB_SVC_TYPE_INTF_ACTIVATE,
					&request, sizeof(request),
					&response, sizeof(response),
					SVC_INTF_ACTIVATE_TIMEOUT);
	if (ret < 0)
		return ret;
	if (response.status != GB_SVC_OP_SUCCESS) {
		dev_err(&svc->dev, "failed to activate interface %u: %u\n",
			intf_id, response.status);
		return -EREMOTEIO;
	}

	*intf_type = response.intf_type;

	return 0;
}

int gb_svc_intf_resume(struct gb_svc *svc, u8 intf_id)
{
	struct gb_svc_intf_resume_request request;
	struct gb_svc_intf_resume_response response;
	int ret;

	request.intf_id = intf_id;

	ret = gb_operation_sync_timeout(svc->connection,
					GB_SVC_TYPE_INTF_RESUME,
					&request, sizeof(request),
					&response, sizeof(response),
					SVC_INTF_RESUME_TIMEOUT);
	if (ret < 0) {
		dev_err(&svc->dev, "failed to send interface resume %u: %d\n",
			intf_id, ret);
		return ret;
	}

	if (response.status != GB_SVC_OP_SUCCESS) {
		dev_err(&svc->dev, "failed to resume interface %u: %u\n",
			intf_id, response.status);
		return -EREMOTEIO;
	}

	return 0;
}

int gb_svc_dme_peer_get(struct gb_svc *svc, u8 intf_id, u16 attr, u16 selector,
			u32 *value)
{
	struct gb_svc_dme_peer_get_request request;
	struct gb_svc_dme_peer_get_response response;
	u16 result;
	int ret;

	request.intf_id = intf_id;
	request.attr = cpu_to_le16(attr);
	request.selector = cpu_to_le16(selector);

	ret = gb_operation_sync(svc->connection, GB_SVC_TYPE_DME_PEER_GET,
				&request, sizeof(request),
				&response, sizeof(response));
	if (ret) {
		dev_err(&svc->dev, "failed to get DME attribute (%u 0x%04x %u): %d\n",
			intf_id, attr, selector, ret);
		return ret;
	}

	result = le16_to_cpu(response.result_code);
	if (result) {
		dev_err(&svc->dev, "UniPro error while getting DME attribute (%u 0x%04x %u): %u\n",
			intf_id, attr, selector, result);
		return -EREMOTEIO;
	}

	if (value)
		*value = le32_to_cpu(response.attr_value);

	return 0;
}

int gb_svc_dme_peer_set(struct gb_svc *svc, u8 intf_id, u16 attr, u16 selector,
			u32 value)
{
	struct gb_svc_dme_peer_set_request request;
	struct gb_svc_dme_peer_set_response response;
	u16 result;
	int ret;

	request.intf_id = intf_id;
	request.attr = cpu_to_le16(attr);
	request.selector = cpu_to_le16(selector);
	request.value = cpu_to_le32(value);

	ret = gb_operation_sync(svc->connection, GB_SVC_TYPE_DME_PEER_SET,
				&request, sizeof(request),
				&response, sizeof(response));
	if (ret) {
		dev_err(&svc->dev, "failed to set DME attribute (%u 0x%04x %u %u): %d\n",
			intf_id, attr, selector, value, ret);
		return ret;
	}

	result = le16_to_cpu(response.result_code);
	if (result) {
		dev_err(&svc->dev, "UniPro error while setting DME attribute (%u 0x%04x %u %u): %u\n",
			intf_id, attr, selector, value, result);
		return -EREMOTEIO;
	}

	return 0;
}

int gb_svc_connection_create(struct gb_svc *svc,
			     u8 intf1_id, u16 cport1_id,
			     u8 intf2_id, u16 cport2_id,
			     u8 cport_flags)
{
	struct gb_svc_conn_create_request request;

	request.intf1_id = intf1_id;
	request.cport1_id = cpu_to_le16(cport1_id);
	request.intf2_id = intf2_id;
	request.cport2_id = cpu_to_le16(cport2_id);
	request.tc = 0;		/* TC0 */
	request.flags = cport_flags;

	return gb_operation_sync(svc->connection, GB_SVC_TYPE_CONN_CREATE,
				 &request, sizeof(request), NULL, 0);
}

void gb_svc_connection_destroy(struct gb_svc *svc, u8 intf1_id, u16 cport1_id,
			       u8 intf2_id, u16 cport2_id)
{
	struct gb_svc_conn_destroy_request request;
	struct gb_connection *connection = svc->connection;
	int ret;

	request.intf1_id = intf1_id;
	request.cport1_id = cpu_to_le16(cport1_id);
	request.intf2_id = intf2_id;
	request.cport2_id = cpu_to_le16(cport2_id);

	ret = gb_operation_sync(connection, GB_SVC_TYPE_CONN_DESTROY,
				&request, sizeof(request), NULL, 0);
	if (ret) {
		dev_err(&svc->dev, "failed to destroy connection (%u:%u %u:%u): %d\n",
			intf1_id, cport1_id, intf2_id, cport2_id, ret);
	}
}

/* Creates bi-directional routes between the devices */
int gb_svc_route_create(struct gb_svc *svc, u8 intf1_id, u8 dev1_id,
			u8 intf2_id, u8 dev2_id)
{
	struct gb_svc_route_create_request request;

	request.intf1_id = intf1_id;
	request.dev1_id = dev1_id;
	request.intf2_id = intf2_id;
	request.dev2_id = dev2_id;

	return gb_operation_sync(svc->connection, GB_SVC_TYPE_ROUTE_CREATE,
				 &request, sizeof(request), NULL, 0);
}

/* Destroys bi-directional routes between the devices */
void gb_svc_route_destroy(struct gb_svc *svc, u8 intf1_id, u8 intf2_id)
{
	struct gb_svc_route_destroy_request request;
	int ret;

	request.intf1_id = intf1_id;
	request.intf2_id = intf2_id;

	ret = gb_operation_sync(svc->connection, GB_SVC_TYPE_ROUTE_DESTROY,
				&request, sizeof(request), NULL, 0);
	if (ret) {
		dev_err(&svc->dev, "failed to destroy route (%u %u): %d\n",
			intf1_id, intf2_id, ret);
	}
}

int gb_svc_intf_set_power_mode(struct gb_svc *svc, u8 intf_id, u8 hs_series,
			       u8 tx_mode, u8 tx_gear, u8 tx_nlanes,
			       u8 tx_amplitude, u8 tx_hs_equalizer,
			       u8 rx_mode, u8 rx_gear, u8 rx_nlanes,
			       u8 flags, u32 quirks,
			       struct gb_svc_l2_timer_cfg *local,
			       struct gb_svc_l2_timer_cfg *remote)
{
	struct gb_svc_intf_set_pwrm_request request;
	struct gb_svc_intf_set_pwrm_response response;
	int ret;
	u16 result_code;

	memset(&request, 0, sizeof(request));

	request.intf_id = intf_id;
	request.hs_series = hs_series;
	request.tx_mode = tx_mode;
	request.tx_gear = tx_gear;
	request.tx_nlanes = tx_nlanes;
	request.tx_amplitude = tx_amplitude;
	request.tx_hs_equalizer = tx_hs_equalizer;
	request.rx_mode = rx_mode;
	request.rx_gear = rx_gear;
	request.rx_nlanes = rx_nlanes;
	request.flags = flags;
	request.quirks = cpu_to_le32(quirks);
	if (local)
		request.local_l2timerdata = *local;
	if (remote)
		request.remote_l2timerdata = *remote;

	ret = gb_operation_sync(svc->connection, GB_SVC_TYPE_INTF_SET_PWRM,
				&request, sizeof(request),
				&response, sizeof(response));
	if (ret < 0)
		return ret;

	result_code = response.result_code;
	if (result_code != GB_SVC_SETPWRM_PWR_LOCAL) {
		dev_err(&svc->dev, "set power mode = %d\n", result_code);
		return -EIO;
	}

	return 0;
}
EXPORT_SYMBOL_GPL(gb_svc_intf_set_power_mode);

int gb_svc_intf_set_power_mode_hibernate(struct gb_svc *svc, u8 intf_id)
{
	struct gb_svc_intf_set_pwrm_request request;
	struct gb_svc_intf_set_pwrm_response response;
	int ret;
	u16 result_code;

	memset(&request, 0, sizeof(request));

	request.intf_id = intf_id;
	request.hs_series = GB_SVC_UNIPRO_HS_SERIES_A;
	request.tx_mode = GB_SVC_UNIPRO_HIBERNATE_MODE;
	request.rx_mode = GB_SVC_UNIPRO_HIBERNATE_MODE;

	ret = gb_operation_sync(svc->connection, GB_SVC_TYPE_INTF_SET_PWRM,
				&request, sizeof(request),
				&response, sizeof(response));
	if (ret < 0) {
		dev_err(&svc->dev,
			"failed to send set power mode operation to interface %u: %d\n",
			intf_id, ret);
		return ret;
	}

	result_code = response.result_code;
	if (result_code != GB_SVC_SETPWRM_PWR_OK) {
		dev_err(&svc->dev,
			"failed to hibernate the link for interface %u: %u\n",
			intf_id, result_code);
		return -EIO;
	}

	return 0;
}

int gb_svc_ping(struct gb_svc *svc)
{
	return gb_operation_sync_timeout(svc->connection, GB_SVC_TYPE_PING,
					 NULL, 0, NULL, 0,
					 GB_OPERATION_TIMEOUT_DEFAULT * 2);
}

static int gb_svc_version_request(struct gb_operation *op)
{
	struct gb_connection *connection = op->connection;
	struct gb_svc *svc = gb_connection_get_data(connection);
	struct gb_svc_version_request *request;
	struct gb_svc_version_response *response;

	if (op->request->payload_size < sizeof(*request)) {
		dev_err(&svc->dev, "short version request (%zu < %zu)\n",
			op->request->payload_size,
			sizeof(*request));
		return -EINVAL;
	}

	request = op->request->payload;

	if (request->major > GB_SVC_VERSION_MAJOR) {
		dev_warn(&svc->dev, "unsupported major version (%u > %u)\n",
			 request->major, GB_SVC_VERSION_MAJOR);
		return -ENOTSUPP;
	}

	svc->protocol_major = request->major;
	svc->protocol_minor = request->minor;

	if (!gb_operation_response_alloc(op, sizeof(*response), GFP_KERNEL))
		return -ENOMEM;

	response = op->response->payload;
	response->major = svc->protocol_major;
	response->minor = svc->protocol_minor;

	return 0;
}

static ssize_t pwr_debugfs_voltage_read(struct file *file, char __user *buf,
					size_t len, loff_t *offset)
{
	struct svc_debugfs_pwrmon_rail *pwrmon_rails =
		file_inode(file)->i_private;
	struct gb_svc *svc = pwrmon_rails->svc;
	int ret, desc;
	u32 value;
	char buff[16];

	ret = gb_svc_pwrmon_sample_get(svc, pwrmon_rails->id,
				       GB_SVC_PWRMON_TYPE_VOL, &value);
	if (ret) {
		dev_err(&svc->dev,
			"failed to get voltage sample %u: %d\n",
			pwrmon_rails->id, ret);
		return ret;
	}

	desc = scnprintf(buff, sizeof(buff), "%u\n", value);

	return simple_read_from_buffer(buf, len, offset, buff, desc);
}

static ssize_t pwr_debugfs_current_read(struct file *file, char __user *buf,
					size_t len, loff_t *offset)
{
	struct svc_debugfs_pwrmon_rail *pwrmon_rails =
		file_inode(file)->i_private;
	struct gb_svc *svc = pwrmon_rails->svc;
	int ret, desc;
	u32 value;
	char buff[16];

	ret = gb_svc_pwrmon_sample_get(svc, pwrmon_rails->id,
				       GB_SVC_PWRMON_TYPE_CURR, &value);
	if (ret) {
		dev_err(&svc->dev,
			"failed to get current sample %u: %d\n",
			pwrmon_rails->id, ret);
		return ret;
	}

	desc = scnprintf(buff, sizeof(buff), "%u\n", value);

	return simple_read_from_buffer(buf, len, offset, buff, desc);
}

static ssize_t pwr_debugfs_power_read(struct file *file, char __user *buf,
				      size_t len, loff_t *offset)
{
	struct svc_debugfs_pwrmon_rail *pwrmon_rails =
		file_inode(file)->i_private;
	struct gb_svc *svc = pwrmon_rails->svc;
	int ret, desc;
	u32 value;
	char buff[16];

	ret = gb_svc_pwrmon_sample_get(svc, pwrmon_rails->id,
				       GB_SVC_PWRMON_TYPE_PWR, &value);
	if (ret) {
		dev_err(&svc->dev, "failed to get power sample %u: %d\n",
			pwrmon_rails->id, ret);
		return ret;
	}

	desc = scnprintf(buff, sizeof(buff), "%u\n", value);

	return simple_read_from_buffer(buf, len, offset, buff, desc);
}

static const struct file_operations pwrmon_debugfs_voltage_fops = {
	.read		= pwr_debugfs_voltage_read,
};

static const struct file_operations pwrmon_debugfs_current_fops = {
	.read		= pwr_debugfs_current_read,
};

static const struct file_operations pwrmon_debugfs_power_fops = {
	.read		= pwr_debugfs_power_read,
};

static void gb_svc_pwrmon_debugfs_init(struct gb_svc *svc)
{
	int i;
	size_t bufsize;
	struct dentry *dent;
	struct gb_svc_pwrmon_rail_names_get_response *rail_names;
	u8 rail_count;

	dent = debugfs_create_dir("pwrmon", svc->debugfs_dentry);
	if (IS_ERR_OR_NULL(dent))
		return;

	if (gb_svc_pwrmon_rail_count_get(svc, &rail_count))
		goto err_pwrmon_debugfs;

	if (!rail_count || rail_count > GB_SVC_PWRMON_MAX_RAIL_COUNT)
		goto err_pwrmon_debugfs;

	bufsize = sizeof(*rail_names) +
		GB_SVC_PWRMON_RAIL_NAME_BUFSIZE * rail_count;

	rail_names = kzalloc(bufsize, GFP_KERNEL);
	if (!rail_names)
		goto err_pwrmon_debugfs;

	svc->pwrmon_rails = kzalloc_objs(*svc->pwrmon_rails, rail_count);
	if (!svc->pwrmon_rails)
		goto err_pwrmon_debugfs_free;

	if (gb_svc_pwrmon_rail_names_get(svc, rail_names, bufsize))
		goto err_pwrmon_debugfs_free;

	for (i = 0; i < rail_count; i++) {
		struct dentry *dir;
		struct svc_debugfs_pwrmon_rail *rail = &svc->pwrmon_rails[i];
		char fname[GB_SVC_PWRMON_RAIL_NAME_BUFSIZE];

		snprintf(fname, sizeof(fname), "%s",
			 (char *)&rail_names->name[i]);

		rail->id = i;
		rail->svc = svc;

		dir = debugfs_create_dir(fname, dent);
		debugfs_create_file("voltage_now", 0444, dir, rail,
				    &pwrmon_debugfs_voltage_fops);
		debugfs_create_file("current_now", 0444, dir, rail,
				    &pwrmon_debugfs_current_fops);
		debugfs_create_file("power_now", 0444, dir, rail,
				    &pwrmon_debugfs_power_fops);
	}

	kfree(rail_names);
	return;

err_pwrmon_debugfs_free:
	kfree(rail_names);
	kfree(svc->pwrmon_rails);
	svc->pwrmon_rails = NULL;

err_pwrmon_debugfs:
	debugfs_remove(dent);
}

static void gb_svc_debugfs_init(struct gb_svc *svc)
{
	svc->debugfs_dentry = debugfs_create_dir(dev_name(&svc->dev),
						 gb_debugfs_get());
	gb_svc_pwrmon_debugfs_init(svc);
}

static void gb_svc_debugfs_exit(struct gb_svc *svc)
{
	debugfs_remove_recursive(svc->debugfs_dentry);
	kfree(svc->pwrmon_rails);
	svc->pwrmon_rails = NULL;
}

static int gb_svc_hello(struct gb_operation *op)
{
	struct gb_connection *connection = op->connection;
	struct gb_svc *svc = gb_connection_get_data(connection);
	struct gb_svc_hello_request *hello_request;
	int ret;

	if (op->request->payload_size < sizeof(*hello_request)) {
		dev_warn(&svc->dev, "short hello request (%zu < %zu)\n",
			 op->request->payload_size,
			 sizeof(*hello_request));
		return -EINVAL;
	}

	hello_request = op->request->payload;
	svc->endo_id = le16_to_cpu(hello_request->endo_id);
	svc->ap_intf_id = hello_request->interface_id;

	ret = device_add(&svc->dev);
	if (ret) {
		dev_err(&svc->dev, "failed to register svc device: %d\n", ret);
		return ret;
	}

	ret = gb_svc_watchdog_create(svc);
	if (ret) {
		dev_err(&svc->dev, "failed to create watchdog: %d\n", ret);
		goto err_deregister_svc;
	}

	/*
	 * FIXME: This is a temporary hack to reconfigure the link at HELLO
	 * (which abuses the deferred request processing mechanism).
	 */
	ret = gb_svc_queue_deferred_request(op);
	if (ret)
		goto err_destroy_watchdog;

	gb_svc_debugfs_init(svc);

	return 0;

err_destroy_watchdog:
	gb_svc_watchdog_destroy(svc);
err_deregister_svc:
	device_del(&svc->dev);

	return ret;
}

static struct gb_interface *gb_svc_interface_lookup(struct gb_svc *svc,
						    u8 intf_id)
{
	struct gb_host_device *hd = svc->hd;
	struct gb_module *module;
	size_t num_interfaces;
	u8 module_id;

	list_for_each_entry(module, &hd->modules, hd_node) {
		module_id = module->module_id;
		num_interfaces = module->num_interfaces;

		if (intf_id >= module_id &&
		    intf_id < module_id + num_interfaces) {
			return module->interfaces[intf_id - module_id];
		}
	}

	return NULL;
}

static struct gb_module *gb_svc_module_lookup(struct gb_svc *svc, u8 module_id)
{
	struct gb_host_device *hd = svc->hd;
	struct gb_module *module;

	list_for_each_entry(module, &hd->modules, hd_node) {
		if (module->module_id == module_id)
			return module;
	}

	return NULL;
}

static void gb_svc_process_hello_deferred(struct gb_operation *operation)
{
	struct gb_connection *connection = operation->connection;
	struct gb_svc *svc = gb_connection_get_data(connection);
	int ret;

	/*
	 * XXX This is a hack/work-around to reconfigure the APBridgeA-Switch
	 * link to PWM G2, 1 Lane, Slow Auto, so that it has sufficient
	 * bandwidth for 3 audio streams plus boot-over-UniPro of a hot-plugged
	 * module.
	 *
	 * The code should be removed once SW-2217, Heuristic for UniPro
	 * Power Mode Changes is resolved.
	 */
	ret = gb_svc_intf_set_power_mode(svc, svc->ap_intf_id,
					 GB_SVC_UNIPRO_HS_SERIES_A,
					 GB_SVC_UNIPRO_SLOW_AUTO_MODE,
					 2, 1,
					 GB_SVC_SMALL_AMPLITUDE,
					 GB_SVC_NO_DE_EMPHASIS,
					 GB_SVC_UNIPRO_SLOW_AUTO_MODE,
					 2, 1,
					 0, 0,
					 NULL, NULL);

	if (ret)
		dev_warn(&svc->dev,
			 "power mode change failed on AP to switch link: %d\n",
			 ret);
}

static void gb_svc_process_module_inserted(struct gb_operation *operation)
{
	struct gb_svc_module_inserted_request *request;
	struct gb_connection *connection = operation->connection;
	struct gb_svc *svc = gb_connection_get_data(connection);
	struct gb_host_device *hd = svc->hd;
	struct gb_module *module;
	size_t num_interfaces;
	u8 module_id;
	u16 flags;
	int ret;

	/* The request message size has already been verified. */
	request = operation->request->payload;
	module_id = request->primary_intf_id;
	num_interfaces = request->intf_count;
	flags = le16_to_cpu(request->flags);

	dev_dbg(&svc->dev, "%s - id = %u, num_interfaces = %zu, flags = 0x%04x\n",
		__func__, module_id, num_interfaces, flags);

	if (flags & GB_SVC_MODULE_INSERTED_FLAG_NO_PRIMARY) {
		dev_warn(&svc->dev, "no primary interface detected on module %u\n",
			 module_id);
	}

	module = gb_svc_module_lookup(svc, module_id);
	if (module) {
		dev_warn(&svc->dev, "unexpected module-inserted event %u\n",
			 module_id);
		return;
	}

	module = gb_module_create(hd, module_id, num_interfaces);
	if (!module) {
		dev_err(&svc->dev, "failed to create module\n");
		return;
	}

	ret = gb_module_add(module);
	if (ret) {
		gb_module_put(module);
		return;
	}

	list_add(&module->hd_node, &hd->modules);
}

static void gb_svc_process_module_removed(struct gb_operation *operation)
{
	struct gb_svc_module_removed_request *request;
	struct gb_connection *connection = operation->connection;
	struct gb_svc *svc = gb_connection_get_data(connection);
	struct gb_module *module;
	u8 module_id;

	/* The request message size has already been verified. */
	request = operation->request->payload;
	module_id = request->primary_intf_id;

	dev_dbg(&svc->dev, "%s - id = %u\n", __func__, module_id);

	module = gb_svc_module_lookup(svc, module_id);
	if (!module) {
		dev_warn(&svc->dev, "unexpected module-removed event %u\n",
			 module_id);
		return;
	}

	module->disconnected = true;

	gb_module_del(module);
	list_del(&module->hd_node);
	gb_module_put(module);
}

static void gb_svc_process_intf_oops(struct gb_operation *operation)
{
	struct gb_svc_intf_oops_request *request;
	struct gb_connection *connection = operation->connection;
	struct gb_svc *svc = gb_connection_get_data(connection);
	struct gb_interface *intf;
	u8 intf_id;
	u8 reason;

	/* The request message size has already been verified. */
	request = operation->request->payload;
	intf_id = request->intf_id;
	reason = request->reason;

	intf = gb_svc_interface_lookup(svc, intf_id);
	if (!intf) {
		dev_warn(&svc->dev, "unexpected interface-oops event %u\n",
			 intf_id);
		return;
	}

	dev_info(&svc->dev, "Deactivating interface %u, interface oops reason = %u\n",
		 intf_id, reason);

	mutex_lock(&intf->mutex);
	intf->disconnected = true;
	gb_interface_disable(intf);
	gb_interface_deactivate(intf);
	mutex_unlock(&intf->mutex);
}

static void gb_svc_process_intf_mailbox_event(struct gb_operation *operation)
{
	struct gb_svc_intf_mailbox_event_request *request;
	struct gb_connection *connection = operation->connection;
	struct gb_svc *svc = gb_connection_get_data(connection);
	struct gb_interface *intf;
	u8 intf_id;
	u16 result_code;
	u32 mailbox;

	/* The request message size has already been verified. */
	request = operation->request->payload;
	intf_id = request->intf_id;
	result_code = le16_to_cpu(request->result_code);
	mailbox = le32_to_cpu(request->mailbox);

	dev_dbg(&svc->dev, "%s - id = %u, result = 0x%04x, mailbox = 0x%08x\n",
		__func__, intf_id, result_code, mailbox);

	intf = gb_svc_interface_lookup(svc, intf_id);
	if (!intf) {
		dev_warn(&svc->dev, "unexpected mailbox event %u\n", intf_id);
		return;
	}

	gb_interface_mailbox_event(intf, result_code, mailbox);
}

static void gb_svc_process_deferred_request(struct work_struct *work)
{
	struct gb_svc_deferred_request *dr;
	struct gb_operation *operation;
	struct gb_svc *svc;
	u8 type;

	dr = container_of(work, struct gb_svc_deferred_request, work);
	operation = dr->operation;
	svc = gb_connection_get_data(operation->connection);
	type = operation->request->header->type;

	switch (type) {
	case GB_SVC_TYPE_SVC_HELLO:
		gb_svc_process_hello_deferred(operation);
		break;
	case GB_SVC_TYPE_MODULE_INSERTED:
		gb_svc_process_module_inserted(operation);
		break;
	case GB_SVC_TYPE_MODULE_REMOVED:
		gb_svc_process_module_removed(operation);
		break;
	case GB_SVC_TYPE_INTF_MAILBOX_EVENT:
		gb_svc_process_intf_mailbox_event(operation);
		break;
	case GB_SVC_TYPE_INTF_OOPS:
		gb_svc_process_intf_oops(operation);
		break;
	default:
		dev_err(&svc->dev, "bad deferred request type: 0x%02x\n", type);
	}

	gb_operation_put(operation);
	kfree(dr);
}

static int gb_svc_queue_deferred_request(struct gb_operation *operation)
{
	struct gb_svc *svc = gb_connection_get_data(operation->connection);
	struct gb_svc_deferred_request *dr;

	dr = kmalloc_obj(*dr);
	if (!dr)
		return -ENOMEM;

	gb_operation_get(operation);

	dr->operation = operation;
	INIT_WORK(&dr->work, gb_svc_process_deferred_request);

	queue_work(svc->wq, &dr->work);

	return 0;
}

static int gb_svc_intf_reset_recv(struct gb_operation *op)
{
	struct gb_svc *svc = gb_connection_get_data(op->connection);
	struct gb_message *request = op->request;
	struct gb_svc_intf_reset_request *reset;

	if (request->payload_size < sizeof(*reset)) {
		dev_warn(&svc->dev, "short reset request received (%zu < %zu)\n",
			 request->payload_size, sizeof(*reset));
		return -EINVAL;
	}
	reset = request->payload;

	/* FIXME Reset the interface here */

	return 0;
}

static int gb_svc_module_inserted_recv(struct gb_operation *op)
{
	struct gb_svc *svc = gb_connection_get_data(op->connection);
	struct gb_svc_module_inserted_request *request;

	if (op->request->payload_size < sizeof(*request)) {
		dev_warn(&svc->dev, "short module-inserted request received (%zu < %zu)\n",
			 op->request->payload_size, sizeof(*request));
		return -EINVAL;
	}

	request = op->request->payload;

	dev_dbg(&svc->dev, "%s - id = %u\n", __func__,
		request->primary_intf_id);

	return gb_svc_queue_deferred_request(op);
}

static int gb_svc_module_removed_recv(struct gb_operation *op)
{
	struct gb_svc *svc = gb_connection_get_data(op->connection);
	struct gb_svc_module_removed_request *request;

	if (op->request->payload_size < sizeof(*request)) {
		dev_warn(&svc->dev, "short module-removed request received (%zu < %zu)\n",
			 op->request->payload_size, sizeof(*request));
		return -EINVAL;
	}

	request = op->request->payload;

	dev_dbg(&svc->dev, "%s - id = %u\n", __func__,
		request->primary_intf_id);

	return gb_svc_queue_deferred_request(op);
}

static int gb_svc_intf_oops_recv(struct gb_operation *op)
{
	struct gb_svc *svc = gb_connection_get_data(op->connection);
	struct gb_svc_intf_oops_request *request;

	if (op->request->payload_size < sizeof(*request)) {
		dev_warn(&svc->dev, "short intf-oops request received (%zu < %zu)\n",
			 op->request->payload_size, sizeof(*request));
		return -EINVAL;
	}

	return gb_svc_queue_deferred_request(op);
}

static int gb_svc_intf_mailbox_event_recv(struct gb_operation *op)
{
	struct gb_svc *svc = gb_connection_get_data(op->connection);
	struct gb_svc_intf_mailbox_event_request *request;

	if (op->request->payload_size < sizeof(*request)) {
		dev_warn(&svc->dev, "short mailbox request received (%zu < %zu)\n",
			 op->request->payload_size, sizeof(*request));
		return -EINVAL;
	}

	request = op->request->payload;

	dev_dbg(&svc->dev, "%s - id = %u\n", __func__, request->intf_id);

	return gb_svc_queue_deferred_request(op);
}

static int gb_svc_request_handler(struct gb_operation *op)
{
	struct gb_connection *connection = op->connection;
	struct gb_svc *svc = gb_connection_get_data(connection);
	u8 type = op->type;
	int ret = 0;

	/*
	 * SVC requests need to follow a specific order (at least initially) and
	 * below code takes care of enforcing that. The expected order is:
	 * - PROTOCOL_VERSION
	 * - SVC_HELLO
	 * - Any other request, but the earlier two.
	 *
	 * Incoming requests are guaranteed to be serialized and so we don't
	 * need to protect 'state' for any races.
	 */
	switch (type) {
	case GB_SVC_TYPE_PROTOCOL_VERSION:
		if (svc->state != GB_SVC_STATE_RESET)
			ret = -EINVAL;
		break;
	case GB_SVC_TYPE_SVC_HELLO:
		if (svc->state != GB_SVC_STATE_PROTOCOL_VERSION)
			ret = -EINVAL;
		break;
	default:
		if (svc->state != GB_SVC_STATE_SVC_HELLO)
			ret = -EINVAL;
		break;
	}

	if (ret) {
		dev_warn(&svc->dev, "unexpected request 0x%02x received (state %u)\n",
			 type, svc->state);
		return ret;
	}

	switch (type) {
	case GB_SVC_TYPE_PROTOCOL_VERSION:
		ret = gb_svc_version_request(op);
		if (!ret)
			svc->state = GB_SVC_STATE_PROTOCOL_VERSION;
		return ret;
	case GB_SVC_TYPE_SVC_HELLO:
		ret = gb_svc_hello(op);
		if (!ret)
			svc->state = GB_SVC_STATE_SVC_HELLO;
		return ret;
	case GB_SVC_TYPE_INTF_RESET:
		return gb_svc_intf_reset_recv(op);
	case GB_SVC_TYPE_MODULE_INSERTED:
		return gb_svc_module_inserted_recv(op);
	case GB_SVC_TYPE_MODULE_REMOVED:
		return gb_svc_module_removed_recv(op);
	case GB_SVC_TYPE_INTF_MAILBOX_EVENT:
		return gb_svc_intf_mailbox_event_recv(op);
	case GB_SVC_TYPE_INTF_OOPS:
		return gb_svc_intf_oops_recv(op);
	default:
		dev_warn(&svc->dev, "unsupported request 0x%02x\n", type);
		return -EINVAL;
	}
}

static void gb_svc_release(struct device *dev)
{
	struct gb_svc *svc = to_gb_svc(dev);

	if (svc->connection)
		gb_connection_destroy(svc->connection);
	ida_destroy(&svc->device_id_map);
	destroy_workqueue(svc->wq);
	kfree(svc);
}

const struct device_type greybus_svc_type = {
	.name		= "greybus_svc",
	.release	= gb_svc_release,
};

struct gb_svc *gb_svc_create(struct gb_host_device *hd)
{
	struct gb_svc *svc;

	svc = kzalloc_obj(*svc);
	if (!svc)
		return NULL;

	svc->wq = alloc_ordered_workqueue("%s:svc", 0, dev_name(&hd->dev));
	if (!svc->wq) {
		kfree(svc);
		return NULL;
	}

	svc->dev.parent = &hd->dev;
	svc->dev.bus = &greybus_bus_type;
	svc->dev.type = &greybus_svc_type;
	svc->dev.groups = svc_groups;
	svc->dev.dma_mask = svc->dev.parent->dma_mask;
	device_initialize(&svc->dev);

	dev_set_name(&svc->dev, "%d-svc", hd->bus_id);

	ida_init(&svc->device_id_map);
	svc->state = GB_SVC_STATE_RESET;
	svc->hd = hd;

	svc->connection = gb_connection_create_static(hd, GB_SVC_CPORT_ID,
						      gb_svc_request_handler);
	if (IS_ERR(svc->connection)) {
		dev_err(&svc->dev, "failed to create connection: %ld\n",
			PTR_ERR(svc->connection));
		goto err_put_device;
	}

	gb_connection_set_data(svc->connection, svc);

	return svc;

err_put_device:
	put_device(&svc->dev);
	return NULL;
}

int gb_svc_add(struct gb_svc *svc)
{
	int ret;

	/*
	 * The SVC protocol is currently driven by the SVC, so the SVC device
	 * is added from the connection request handler when enough
	 * information has been received.
	 */
	ret = gb_connection_enable(svc->connection);
	if (ret)
		return ret;

	return 0;
}

static void gb_svc_remove_modules(struct gb_svc *svc)
{
	struct gb_host_device *hd = svc->hd;
	struct gb_module *module, *tmp;

	list_for_each_entry_safe(module, tmp, &hd->modules, hd_node) {
		gb_module_del(module);
		list_del(&module->hd_node);
		gb_module_put(module);
	}
}

void gb_svc_del(struct gb_svc *svc)
{
	gb_connection_disable_rx(svc->connection);

	/*
	 * The SVC device may have been registered from the request handler.
	 */
	if (device_is_registered(&svc->dev)) {
		gb_svc_debugfs_exit(svc);
		gb_svc_watchdog_destroy(svc);
		device_del(&svc->dev);
	}

	flush_workqueue(svc->wq);

	gb_svc_remove_modules(svc);

	gb_connection_disable(svc->connection);
}

void gb_svc_put(struct gb_svc *svc)
{
	put_device(&svc->dev);
}