// SPDX-License-Identifier: GPL-2.0
/*
 * MIPI SyS-T framing protocol for STM devices.
 * Copyright (c) 2018, Intel Corporation.
 */

#include <linux/configfs.h>
#include <linux/module.h>
#include <linux/device.h>
#include <linux/slab.h>
#include <linux/uuid.h>
#include <linux/stm.h>
#include "stm.h"

enum sys_t_message_type {
	MIPI_SYST_TYPE_BUILD	= 0,
	MIPI_SYST_TYPE_SHORT32,
	MIPI_SYST_TYPE_STRING,
	MIPI_SYST_TYPE_CATALOG,
	MIPI_SYST_TYPE_RAW	= 6,
	MIPI_SYST_TYPE_SHORT64,
	MIPI_SYST_TYPE_CLOCK,
};

enum sys_t_message_severity {
	MIPI_SYST_SEVERITY_MAX	= 0,
	MIPI_SYST_SEVERITY_FATAL,
	MIPI_SYST_SEVERITY_ERROR,
	MIPI_SYST_SEVERITY_WARNING,
	MIPI_SYST_SEVERITY_INFO,
	MIPI_SYST_SEVERITY_USER1,
	MIPI_SYST_SEVERITY_USER2,
	MIPI_SYST_SEVERITY_DEBUG,
};

enum sys_t_message_build_subtype {
	MIPI_SYST_BUILD_ID_COMPACT32 = 0,
	MIPI_SYST_BUILD_ID_COMPACT64,
	MIPI_SYST_BUILD_ID_LONG,
};

enum sys_t_message_clock_subtype {
	MIPI_SYST_CLOCK_TRANSPORT_SYNC = 1,
};

enum sys_t_message_string_subtype {
	MIPI_SYST_STRING_GENERIC	= 1,
	MIPI_SYST_STRING_FUNCTIONENTER,
	MIPI_SYST_STRING_FUNCTIONEXIT,
	MIPI_SYST_STRING_INVALIDPARAM	= 5,
	MIPI_SYST_STRING_ASSERT		= 7,
	MIPI_SYST_STRING_PRINTF_32	= 11,
	MIPI_SYST_STRING_PRINTF_64	= 12,
};

#define MIPI_SYST_TYPE(t)		((u32)(MIPI_SYST_TYPE_ ## t))
#define MIPI_SYST_SEVERITY(s)		((u32)(MIPI_SYST_SEVERITY_ ## s) << 4)
#define MIPI_SYST_OPT_LOC		BIT(8)
#define MIPI_SYST_OPT_LEN		BIT(9)
#define MIPI_SYST_OPT_CHK		BIT(10)
#define MIPI_SYST_OPT_TS		BIT(11)
#define MIPI_SYST_UNIT(u)		((u32)(u) << 12)
#define MIPI_SYST_ORIGIN(o)		((u32)(o) << 16)
#define MIPI_SYST_OPT_GUID		BIT(23)
#define MIPI_SYST_SUBTYPE(s)		((u32)(MIPI_SYST_ ## s) << 24)
#define MIPI_SYST_UNITLARGE(u)		(MIPI_SYST_UNIT(u & 0xf) | \
					 MIPI_SYST_ORIGIN(u >> 4))
#define MIPI_SYST_TYPES(t, s)		(MIPI_SYST_TYPE(t) | \
					 MIPI_SYST_SUBTYPE(t ## _ ## s))

#define DATA_HEADER	(MIPI_SYST_TYPES(STRING, GENERIC)	| \
			 MIPI_SYST_SEVERITY(INFO)		| \
			 MIPI_SYST_OPT_GUID)

#define CLOCK_SYNC_HEADER	(MIPI_SYST_TYPES(CLOCK, TRANSPORT_SYNC)	| \
				 MIPI_SYST_SEVERITY(MAX))

struct sys_t_policy_node {
	uuid_t		uuid;
	bool		do_len;
	unsigned long	ts_interval;
	unsigned long	clocksync_interval;
};

struct sys_t_output {
	struct sys_t_policy_node	node;
	unsigned long	ts_jiffies;
	unsigned long	clocksync_jiffies;
};

static void sys_t_policy_node_init(void *priv)
{
	struct sys_t_policy_node *pn = priv;

	generate_random_uuid(pn->uuid.b);
}

static int sys_t_output_open(void *priv, struct stm_output *output)
{
	struct sys_t_policy_node *pn = priv;
	struct sys_t_output *opriv;

	opriv = kzalloc(sizeof(*opriv), GFP_ATOMIC);
	if (!opriv)
		return -ENOMEM;

	memcpy(&opriv->node, pn, sizeof(opriv->node));
	output->pdrv_private = opriv;

	return 0;
}

static void sys_t_output_close(struct stm_output *output)
{
	kfree(output->pdrv_private);
}

static ssize_t sys_t_policy_uuid_show(struct config_item *item,
				      char *page)
{
	struct sys_t_policy_node *pn = to_pdrv_policy_node(item);

	return sprintf(page, "%pU\n", &pn->uuid);
}

static ssize_t
sys_t_policy_uuid_store(struct config_item *item, const char *page,
			size_t count)
{
	struct mutex *mutexp = &item->ci_group->cg_subsys->su_mutex;
	struct sys_t_policy_node *pn = to_pdrv_policy_node(item);
	int ret;

	mutex_lock(mutexp);
	ret = uuid_parse(page, &pn->uuid);
	mutex_unlock(mutexp);

	return ret < 0 ? ret : count;
}

CONFIGFS_ATTR(sys_t_policy_, uuid);

static ssize_t sys_t_policy_do_len_show(struct config_item *item,
				      char *page)
{
	struct sys_t_policy_node *pn = to_pdrv_policy_node(item);

	return sprintf(page, "%d\n", pn->do_len);
}

static ssize_t
sys_t_policy_do_len_store(struct config_item *item, const char *page,
			size_t count)
{
	struct mutex *mutexp = &item->ci_group->cg_subsys->su_mutex;
	struct sys_t_policy_node *pn = to_pdrv_policy_node(item);
	int ret;

	mutex_lock(mutexp);
	ret = kstrtobool(page, &pn->do_len);
	mutex_unlock(mutexp);

	return ret ? ret : count;
}

CONFIGFS_ATTR(sys_t_policy_, do_len);

static ssize_t sys_t_policy_ts_interval_show(struct config_item *item,
					     char *page)
{
	struct sys_t_policy_node *pn = to_pdrv_policy_node(item);

	return sprintf(page, "%u\n", jiffies_to_msecs(pn->ts_interval));
}

static ssize_t
sys_t_policy_ts_interval_store(struct config_item *item, const char *page,
			       size_t count)
{
	struct mutex *mutexp = &item->ci_group->cg_subsys->su_mutex;
	struct sys_t_policy_node *pn = to_pdrv_policy_node(item);
	unsigned int ms;
	int ret;

	mutex_lock(mutexp);
	ret = kstrtouint(page, 10, &ms);
	mutex_unlock(mutexp);

	if (!ret) {
		pn->ts_interval = msecs_to_jiffies(ms);
		return count;
	}

	return ret;
}

CONFIGFS_ATTR(sys_t_policy_, ts_interval);

static ssize_t sys_t_policy_clocksync_interval_show(struct config_item *item,
						    char *page)
{
	struct sys_t_policy_node *pn = to_pdrv_policy_node(item);

	return sprintf(page, "%u\n", jiffies_to_msecs(pn->clocksync_interval));
}

static ssize_t
sys_t_policy_clocksync_interval_store(struct config_item *item,
				      const char *page, size_t count)
{
	struct mutex *mutexp = &item->ci_group->cg_subsys->su_mutex;
	struct sys_t_policy_node *pn = to_pdrv_policy_node(item);
	unsigned int ms;
	int ret;

	mutex_lock(mutexp);
	ret = kstrtouint(page, 10, &ms);
	mutex_unlock(mutexp);

	if (!ret) {
		pn->clocksync_interval = msecs_to_jiffies(ms);
		return count;
	}

	return ret;
}

CONFIGFS_ATTR(sys_t_policy_, clocksync_interval);

static struct configfs_attribute *sys_t_policy_attrs[] = {
	&sys_t_policy_attr_uuid,
	&sys_t_policy_attr_do_len,
	&sys_t_policy_attr_ts_interval,
	&sys_t_policy_attr_clocksync_interval,
	NULL,
};

static inline bool sys_t_need_ts(struct sys_t_output *op)
{
	if (op->node.ts_interval &&
	    time_after(op->ts_jiffies + op->node.ts_interval, jiffies)) {
		op->ts_jiffies = jiffies;

		return true;
	}

	return false;
}

static bool sys_t_need_clock_sync(struct sys_t_output *op)
{
	if (op->node.clocksync_interval &&
	    time_after(op->clocksync_jiffies + op->node.clocksync_interval,
		       jiffies)) {
		op->clocksync_jiffies = jiffies;

		return true;
	}

	return false;
}

static ssize_t
sys_t_clock_sync(struct stm_data *data, unsigned int m, unsigned int c)
{
	u32 header = CLOCK_SYNC_HEADER;
	const unsigned char nil = 0;
	u64 payload[2]; /* Clock value and frequency */
	ssize_t sz;

	sz = data->packet(data, m, c, STP_PACKET_DATA, STP_PACKET_TIMESTAMPED,
			  4, (u8 *)&header);
	if (sz <= 0)
		return sz;

	payload[0] = ktime_get_real_ns();
	payload[1] = NSEC_PER_SEC;
	sz = stm_data_write(data, m, c, false, &payload, sizeof(payload));
	if (sz <= 0)
		return sz;

	data->packet(data, m, c, STP_PACKET_FLAG, 0, 0, &nil);

	return sizeof(header) + sizeof(payload);
}

static ssize_t sys_t_write(struct stm_data *data, struct stm_output *output,
			   unsigned int chan, const char *buf, size_t count)
{
	struct sys_t_output *op = output->pdrv_private;
	unsigned int c = output->channel + chan;
	unsigned int m = output->master;
	const unsigned char nil = 0;
	u32 header = DATA_HEADER;
	ssize_t sz;

	/* We require an existing policy node to proceed */
	if (!op)
		return -EINVAL;

	if (sys_t_need_clock_sync(op)) {
		sz = sys_t_clock_sync(data, m, c);
		if (sz <= 0)
			return sz;
	}

	if (op->node.do_len)
		header |= MIPI_SYST_OPT_LEN;
	if (sys_t_need_ts(op))
		header |= MIPI_SYST_OPT_TS;

	/*
	 * STP framing rules for SyS-T frames:
	 *   * the first packet of the SyS-T frame is timestamped;
	 *   * the last packet is a FLAG.
	 */
	/* Message layout: HEADER / GUID / [LENGTH /][TIMESTAMP /] DATA */
	/* HEADER */
	sz = data->packet(data, m, c, STP_PACKET_DATA, STP_PACKET_TIMESTAMPED,
			  4, (u8 *)&header);
	if (sz <= 0)
		return sz;

	/* GUID */
	sz = stm_data_write(data, m, c, false, op->node.uuid.b, UUID_SIZE);
	if (sz <= 0)
		return sz;

	/* [LENGTH] */
	if (op->node.do_len) {
		u16 length = count;

		sz = data->packet(data, m, c, STP_PACKET_DATA, 0, 2,
				  (u8 *)&length);
		if (sz <= 0)
			return sz;
	}

	/* [TIMESTAMP] */
	if (header & MIPI_SYST_OPT_TS) {
		u64 ts = ktime_get_real_ns();

		sz = stm_data_write(data, m, c, false, &ts, sizeof(ts));
		if (sz <= 0)
			return sz;
	}

	/* DATA */
	sz = stm_data_write(data, m, c, false, buf, count);
	if (sz > 0)
		data->packet(data, m, c, STP_PACKET_FLAG, 0, 0, &nil);

	return sz;
}

static const struct stm_protocol_driver sys_t_pdrv = {
	.owner			= THIS_MODULE,
	.name			= "p_sys-t",
	.priv_sz		= sizeof(struct sys_t_policy_node),
	.write			= sys_t_write,
	.policy_attr		= sys_t_policy_attrs,
	.policy_node_init	= sys_t_policy_node_init,
	.output_open		= sys_t_output_open,
	.output_close		= sys_t_output_close,
};

static int sys_t_stm_init(void)
{
	return stm_register_protocol(&sys_t_pdrv);
}

static void sys_t_stm_exit(void)
{
	stm_unregister_protocol(&sys_t_pdrv);
}

module_init(sys_t_stm_init);
module_exit(sys_t_stm_exit);

MODULE_LICENSE("GPL v2");
MODULE_DESCRIPTION("MIPI SyS-T STM framing protocol driver");
MODULE_AUTHOR("Alexander Shishkin <alexander.shishkin@linux.intel.com>");