common.h

/* SPDX-License-Identifier: GPL-2.0 */
/*
 * System Control and Management Interface (SCMI) Message Protocol
 * driver common header file containing some definitions, structures
 * and function prototypes used in all the different SCMI protocols.
 *
 * Copyright (C) 2018-2024 ARM Ltd.
 */
#ifndef _SCMI_COMMON_H
#define _SCMI_COMMON_H

#include <linux/bitfield.h>
#include <linux/completion.h>
#include <linux/device.h>
#include <linux/errno.h>
#include <linux/kernel.h>
#include <linux/hashtable.h>
#include <linux/list.h>
#include <linux/module.h>
#include <linux/refcount.h>
#include <linux/scmi_protocol.h>
#include <linux/spinlock.h>
#include <linux/types.h>

#include <linux/unaligned.h>

#include "protocols.h"
#include "notify.h"

#define SCMI_MAX_CHANNELS		256

#define SCMI_MAX_RESPONSE_TIMEOUT	(2 * MSEC_PER_SEC)

#define SCMI_SHMEM_MAX_PAYLOAD_SIZE	104

enum scmi_error_codes {
	SCMI_SUCCESS = 0,	/* Success */
	SCMI_ERR_SUPPORT = -1,	/* Not supported */
	SCMI_ERR_PARAMS = -2,	/* Invalid Parameters */
	SCMI_ERR_ACCESS = -3,	/* Invalid access/permission denied */
	SCMI_ERR_ENTRY = -4,	/* Not found */
	SCMI_ERR_RANGE = -5,	/* Value out of range */
	SCMI_ERR_BUSY = -6,	/* Device busy */
	SCMI_ERR_COMMS = -7,	/* Communication Error */
	SCMI_ERR_GENERIC = -8,	/* Generic Error */
	SCMI_ERR_HARDWARE = -9,	/* Hardware Error */
	SCMI_ERR_PROTOCOL = -10,/* Protocol Error */
};

static const int scmi_linux_errmap[] = {
	/* better than switch case as long as return value is continuous */
	0,			/* SCMI_SUCCESS */
	-EOPNOTSUPP,		/* SCMI_ERR_SUPPORT */
	-EINVAL,		/* SCMI_ERR_PARAM */
	-EACCES,		/* SCMI_ERR_ACCESS */
	-ENOENT,		/* SCMI_ERR_ENTRY */
	-ERANGE,		/* SCMI_ERR_RANGE */
	-EBUSY,			/* SCMI_ERR_BUSY */
	-ECOMM,			/* SCMI_ERR_COMMS */
	-EIO,			/* SCMI_ERR_GENERIC */
	-EREMOTEIO,		/* SCMI_ERR_HARDWARE */
	-EPROTO,		/* SCMI_ERR_PROTOCOL */
};

static inline int scmi_to_linux_errno(int errno)
{
	int err_idx = -errno;

	if (err_idx >= SCMI_SUCCESS && err_idx < ARRAY_SIZE(scmi_linux_errmap))
		return scmi_linux_errmap[err_idx];
	return -EIO;
}

#define MSG_ID_MASK		GENMASK(7, 0)
#define MSG_XTRACT_ID(hdr)	FIELD_GET(MSG_ID_MASK, (hdr))
#define MSG_TYPE_MASK		GENMASK(9, 8)
#define MSG_XTRACT_TYPE(hdr)	FIELD_GET(MSG_TYPE_MASK, (hdr))
#define MSG_TYPE_COMMAND	0
#define MSG_TYPE_DELAYED_RESP	2
#define MSG_TYPE_NOTIFICATION	3
#define MSG_PROTOCOL_ID_MASK	GENMASK(17, 10)
#define MSG_XTRACT_PROT_ID(hdr)	FIELD_GET(MSG_PROTOCOL_ID_MASK, (hdr))
#define MSG_TOKEN_ID_MASK	GENMASK(27, 18)
#define MSG_XTRACT_TOKEN(hdr)	FIELD_GET(MSG_TOKEN_ID_MASK, (hdr))
#define MSG_TOKEN_MAX		(MSG_XTRACT_TOKEN(MSG_TOKEN_ID_MASK) + 1)

/*
 * Size of @pending_xfers hashtable included in @scmi_xfers_info; ideally, in
 * order to minimize space and collisions, this should equal max_msg, i.e. the
 * maximum number of in-flight messages on a specific platform, but such value
 * is only available at runtime while kernel hashtables are statically sized:
 * pick instead as a fixed static size the maximum number of entries that can
 * fit the whole table into one 4k page.
 */
#define SCMI_PENDING_XFERS_HT_ORDER_SZ		9

/**
 * pack_scmi_header() - packs and returns 32-bit header
 *
 * @hdr: pointer to header containing all the information on message id,
 *	protocol id, sequence id and type.
 *
 * Return: 32-bit packed message header to be sent to the platform.
 */
static inline u32 pack_scmi_header(struct scmi_msg_hdr *hdr)
{
	return FIELD_PREP(MSG_ID_MASK, hdr->id) |
		FIELD_PREP(MSG_TYPE_MASK, hdr->type) |
		FIELD_PREP(MSG_TOKEN_ID_MASK, hdr->seq) |
		FIELD_PREP(MSG_PROTOCOL_ID_MASK, hdr->protocol_id);
}

/**
 * unpack_scmi_header() - unpacks and records message and protocol id
 *
 * @msg_hdr: 32-bit packed message header sent from the platform
 * @hdr: pointer to header to fetch message and protocol id.
 */
static inline void unpack_scmi_header(u32 msg_hdr, struct scmi_msg_hdr *hdr)
{
	hdr->id = MSG_XTRACT_ID(msg_hdr);
	hdr->protocol_id = MSG_XTRACT_PROT_ID(msg_hdr);
	hdr->type = MSG_XTRACT_TYPE(msg_hdr);
}

/*
 * An helper macro to lookup an xfer from the @pending_xfers hashtable
 * using the message sequence number token as a key.
 */
#define XFER_FIND(__ht, __k)					\
({								\
	typeof(__k) k_ = __k;					\
	struct scmi_xfer *xfer_ = NULL;				\
								\
	hash_for_each_possible((__ht), xfer_, node, k_)		\
		if (xfer_->hdr.seq == k_)			\
			break;					\
	xfer_;							\
})

struct scmi_revision_info *
scmi_revision_area_get(const struct scmi_protocol_handle *ph);
void scmi_setup_protocol_implemented(const struct scmi_protocol_handle *ph,
				     u8 *prot_imp);

extern const struct bus_type scmi_bus_type;

#define SCMI_BUS_NOTIFY_DEVICE_REQUEST		0
#define SCMI_BUS_NOTIFY_DEVICE_UNREQUEST	1
extern struct blocking_notifier_head scmi_requested_devices_nh;

struct scmi_device *scmi_device_create(struct device_node *np,
				       struct device *parent, int protocol,
				       const char *name);
void scmi_device_destroy(struct device *parent, int protocol, const char *name);

int scmi_protocol_acquire(const struct scmi_handle *handle, u8 protocol_id);
void scmi_protocol_release(const struct scmi_handle *handle, u8 protocol_id);

/* SCMI Transport */
/**
 * struct scmi_chan_info - Structure representing a SCMI channel information
 *
 * @id: An identifier for this channel: this matches the protocol number
 *      used to initialize this channel
 * @dev: Reference to device in the SCMI hierarchy corresponding to this
 *	 channel
 * @is_p2a: A flag to identify a channel as P2A (RX)
 * @rx_timeout_ms: The configured RX timeout in milliseconds.
 * @max_msg_size: Maximum size of message payload.
 * @handle: Pointer to SCMI entity handle
 * @no_completion_irq: Flag to indicate that this channel has no completion
 *		       interrupt mechanism for synchronous commands.
 *		       This can be dynamically set by transports at run-time
 *		       inside their provided .chan_setup().
 * @transport_info: Transport layer related information
 */
struct scmi_chan_info {
	int id;
	struct device *dev;
	bool is_p2a;
	unsigned int rx_timeout_ms;
	unsigned int max_msg_size;
	struct scmi_handle *handle;
	bool no_completion_irq;
	void *transport_info;
};

/**
 * struct scmi_transport_ops - Structure representing a SCMI transport ops
 *
 * @chan_available: Callback to check if channel is available or not
 * @chan_setup: Callback to allocate and setup a channel
 * @chan_free: Callback to free a channel
 * @get_max_msg: Optional callback to provide max_msg dynamically
 *		 Returns the maximum number of messages for the channel type
 *		 (tx or rx) that can be pending simultaneously in the system
 * @send_message: Callback to send a message
 * @mark_txdone: Callback to mark tx as done
 * @fetch_response: Callback to fetch response
 * @fetch_notification: Callback to fetch notification
 * @clear_channel: Callback to clear a channel
 * @poll_done: Callback to poll transfer status
 */
struct scmi_transport_ops {
	bool (*chan_available)(struct device_node *of_node, int idx);
	int (*chan_setup)(struct scmi_chan_info *cinfo, struct device *dev,
			  bool tx);
	int (*chan_free)(int id, void *p, void *data);
	unsigned int (*get_max_msg)(struct scmi_chan_info *base_cinfo);
	int (*send_message)(struct scmi_chan_info *cinfo,
			    struct scmi_xfer *xfer);
	void (*mark_txdone)(struct scmi_chan_info *cinfo, int ret,
			    struct scmi_xfer *xfer);
	void (*fetch_response)(struct scmi_chan_info *cinfo,
			       struct scmi_xfer *xfer);
	void (*fetch_notification)(struct scmi_chan_info *cinfo,
				   size_t max_len, struct scmi_xfer *xfer);
	void (*clear_channel)(struct scmi_chan_info *cinfo);
	bool (*poll_done)(struct scmi_chan_info *cinfo, struct scmi_xfer *xfer);
};

/**
 * struct scmi_desc - Description of SoC integration
 *
 * @ops: Pointer to the transport specific ops structure
 * @max_rx_timeout_ms: Timeout for communication with SoC (in Milliseconds)
 * @max_msg: Maximum number of messages for a channel type (tx or rx) that can
 *	be pending simultaneously in the system. May be overridden by the
 *	get_max_msg op.
 * @max_msg_size: Maximum size of data payload per message that can be handled.
 * @atomic_threshold: Optional system wide DT-configured threshold, expressed
 *		      in microseconds, for atomic operations.
 *		      Only SCMI synchronous commands reported by the platform
 *		      to have an execution latency lesser-equal to the threshold
 *		      should be considered for atomic mode operation: such
 *		      decision is finally left up to the SCMI drivers.
 * @force_polling: Flag to force this whole transport to use SCMI core polling
 *		   mechanism instead of completion interrupts even if available.
 * @sync_cmds_completed_on_ret: Flag to indicate that the transport assures
 *				synchronous-command messages are atomically
 *				completed on .send_message: no need to poll
 *				actively waiting for a response.
 *				Used by core internally only when polling is
 *				selected as a waiting for reply method: i.e.
 *				if a completion irq was found use that anyway.
 * @atomic_enabled: Flag to indicate that this transport, which is assured not
 *		    to sleep anywhere on the TX path, can be used in atomic mode
 *		    when requested.
 */
struct scmi_desc {
	const struct scmi_transport_ops *ops;
	int max_rx_timeout_ms;
	int max_msg;
	int max_msg_size;
	unsigned int atomic_threshold;
	const bool force_polling;
	const bool sync_cmds_completed_on_ret;
	const bool atomic_enabled;
};

static inline bool is_polling_required(struct scmi_chan_info *cinfo,
				       const struct scmi_desc *desc)
{
	return cinfo->no_completion_irq || desc->force_polling;
}

static inline bool is_transport_polling_capable(const struct scmi_desc *desc)
{
	return desc->ops->poll_done || desc->sync_cmds_completed_on_ret;
}

static inline bool is_polling_enabled(struct scmi_chan_info *cinfo,
				      const struct scmi_desc *desc)
{
	return is_polling_required(cinfo, desc) &&
		is_transport_polling_capable(desc);
}

void scmi_xfer_raw_put(const struct scmi_handle *handle,
		       struct scmi_xfer *xfer);
struct scmi_xfer *scmi_xfer_raw_get(const struct scmi_handle *handle);
struct scmi_chan_info *
scmi_xfer_raw_channel_get(const struct scmi_handle *handle, u8 protocol_id);

int scmi_xfer_raw_inflight_register(const struct scmi_handle *handle,
				    struct scmi_xfer *xfer);

int scmi_xfer_raw_wait_for_message_response(struct scmi_chan_info *cinfo,
					    struct scmi_xfer *xfer,
					    unsigned int timeout_ms);

enum debug_counters {
	SENT_OK,
	SENT_FAIL,
	SENT_FAIL_POLLING_UNSUPPORTED,
	SENT_FAIL_CHANNEL_NOT_FOUND,
	RESPONSE_OK,
	NOTIFICATION_OK,
	DELAYED_RESPONSE_OK,
	XFERS_RESPONSE_TIMEOUT,
	XFERS_RESPONSE_POLLED_TIMEOUT,
	RESPONSE_POLLED_OK,
	ERR_MSG_UNEXPECTED,
	ERR_MSG_INVALID,
	ERR_MSG_NOMEM,
	ERR_PROTOCOL,
	XFERS_INFLIGHT,
	SCMI_DEBUG_COUNTERS_LAST
};

static inline void scmi_inc_count(atomic_t *arr, int stat)
{
	if (IS_ENABLED(CONFIG_ARM_SCMI_DEBUG_COUNTERS))
		atomic_inc(&arr[stat]);
}

static inline void scmi_dec_count(atomic_t *arr, int stat)
{
	if (IS_ENABLED(CONFIG_ARM_SCMI_DEBUG_COUNTERS))
		atomic_dec(&arr[stat]);
}

enum scmi_bad_msg {
	MSG_UNEXPECTED = -1,
	MSG_INVALID = -2,
	MSG_UNKNOWN = -3,
	MSG_NOMEM = -4,
	MSG_MBOX_SPURIOUS = -5,
};

/* Used for compactness and signature validation of the function pointers being
 * passed.
 */
typedef void (*shmem_copy_toio_t)(void __iomem *to, const void *from,
				  size_t count);
typedef void (*shmem_copy_fromio_t)(void *to, const void __iomem *from,
				    size_t count);

/**
 * struct scmi_shmem_io_ops  - I/O operations to read from/write to
 * Shared Memory
 *
 * @toio: Copy data to the shared memory area
 * @fromio: Copy data from the shared memory area
 */
struct scmi_shmem_io_ops {
	shmem_copy_fromio_t fromio;
	shmem_copy_toio_t toio;
};

/* shmem related declarations */
struct scmi_shared_mem;

/**
 * struct scmi_shared_mem_operations  - Transport core operations for
 * Shared Memory
 *
 * @tx_prepare: Prepare the @xfer message for transmission on the chosen @shmem
 * @read_header: Read header of the message currently hold in @shmem
 * @fetch_response: Copy the message response from @shmem into @xfer
 * @fetch_notification: Copy the message notification from @shmem into @xfer
 * @clear_channel: Clear the @shmem channel busy flag
 * @poll_done: Check if poll has completed for @xfer on @shmem
 * @channel_free: Check if @shmem channel is marked as free
 * @channel_intr_enabled: Check is @shmem channel has requested a completion irq
 * @setup_iomap: Setup IO shared memory for channel @cinfo
 */
struct scmi_shared_mem_operations {
	void (*tx_prepare)(struct scmi_shared_mem __iomem *shmem,
			   struct scmi_xfer *xfer,
			   struct scmi_chan_info *cinfo,
			   shmem_copy_toio_t toio);
	u32 (*read_header)(struct scmi_shared_mem __iomem *shmem);

	void (*fetch_response)(struct scmi_shared_mem __iomem *shmem,
			       struct scmi_xfer *xfer,
			       shmem_copy_fromio_t fromio);
	void (*fetch_notification)(struct scmi_shared_mem __iomem *shmem,
				   size_t max_len, struct scmi_xfer *xfer,
				   shmem_copy_fromio_t fromio);
	void (*clear_channel)(struct scmi_shared_mem __iomem *shmem);
	bool (*poll_done)(struct scmi_shared_mem __iomem *shmem,
			  struct scmi_xfer *xfer);
	bool (*channel_free)(struct scmi_shared_mem __iomem *shmem);
	bool (*channel_intr_enabled)(struct scmi_shared_mem __iomem *shmem);
	void __iomem *(*setup_iomap)(struct scmi_chan_info *cinfo,
				     struct device *dev,
				     bool tx, struct resource *res,
				     struct scmi_shmem_io_ops **ops);
};

const struct scmi_shared_mem_operations *scmi_shared_mem_operations_get(void);

/* declarations for message passing transports */
struct scmi_msg_payld;

/* Maximum overhead of message w.r.t. struct scmi_desc.max_msg_size */
#define SCMI_MSG_MAX_PROT_OVERHEAD (2 * sizeof(__le32))

/**
 * struct scmi_message_operations  - Transport core operations for Message
 *
 * @response_size: Get calculated response size for @xfer
 * @command_size: Get calculated command size for @xfer
 * @tx_prepare: Prepare the @xfer message for transmission on the provided @msg
 * @read_header: Read header of the message currently hold in @msg
 * @fetch_response: Copy the message response from @msg into @xfer
 * @fetch_notification: Copy the message notification from @msg into @xfer
 */
struct scmi_message_operations {
	size_t (*response_size)(struct scmi_xfer *xfer);
	size_t (*command_size)(struct scmi_xfer *xfer);
	void (*tx_prepare)(struct scmi_msg_payld *msg, struct scmi_xfer *xfer);
	u32 (*read_header)(struct scmi_msg_payld *msg);
	void (*fetch_response)(struct scmi_msg_payld *msg, size_t len,
			       struct scmi_xfer *xfer);
	void (*fetch_notification)(struct scmi_msg_payld *msg, size_t len,
				   size_t max_len, struct scmi_xfer *xfer);
};

const struct scmi_message_operations *scmi_message_operations_get(void);

/**
 * struct scmi_transport_core_operations  - Transpoert core operations
 *
 * @bad_message_trace: An helper to report a malformed/unexpected message
 * @rx_callback: Callback to report received messages
 * @shmem: Datagram operations for shared memory based transports
 * @msg: Datagram operations for message based transports
 */
struct scmi_transport_core_operations {
	void (*bad_message_trace)(struct scmi_chan_info *cinfo,
				  u32 msg_hdr, enum scmi_bad_msg err);
	void (*rx_callback)(struct scmi_chan_info *cinfo, u32 msg_hdr,
			    void *priv);
	const struct scmi_shared_mem_operations *shmem;
	const struct scmi_message_operations *msg;
};

/**
 * struct scmi_transport  - A structure representing a configured transport
 *
 * @supplier: Device representing the transport and acting as a supplier for
 *	      the core SCMI stack
 * @desc: Transport descriptor
 * @core_ops: A pointer to a pointer used by the core SCMI stack to make the
 *	      core transport operations accessible to the transports.
 */
struct scmi_transport {
	struct device *supplier;
	struct scmi_desc desc;
	struct scmi_transport_core_operations **core_ops;
};

#define DEFINE_SCMI_TRANSPORT_DRIVER(__tag, __drv, __desc, __match, __core_ops)\
static void __tag##_dev_free(void *data)				       \
{									       \
	struct platform_device *spdev = data;				       \
									       \
	platform_device_unregister(spdev);				       \
}									       \
									       \
static int __tag##_probe(struct platform_device *pdev)			       \
{									       \
	struct device *dev = &pdev->dev;				       \
	struct platform_device *spdev;					       \
	struct scmi_transport strans;					       \
	int ret;							       \
									       \
	spdev = platform_device_alloc("arm-scmi", PLATFORM_DEVID_AUTO);	       \
	if (!spdev)							       \
		return -ENOMEM;						       \
									       \
	device_set_of_node_from_dev(&spdev->dev, dev);			       \
									       \
	strans.supplier = dev;						       \
	memcpy(&strans.desc, &(__desc), sizeof(strans.desc));		       \
	strans.core_ops = &(__core_ops);				       \
									       \
	ret = platform_device_add_data(spdev, &strans, sizeof(strans));	       \
	if (ret)							       \
		goto err;						       \
									       \
	spdev->dev.parent = dev;					       \
	ret = platform_device_add(spdev);				       \
	if (ret)							       \
		goto err;						       \
									       \
	return devm_add_action_or_reset(dev, __tag##_dev_free, spdev);	       \
									       \
err:									       \
	platform_device_put(spdev);					       \
	return ret;							       \
}									       \
									       \
static struct platform_driver __drv = {					       \
	.driver = {							       \
		   .name = #__tag "_transport",				       \
		   .of_match_table = __match,				       \
		   },							       \
	.probe = __tag##_probe,						       \
}

void scmi_notification_instance_data_set(const struct scmi_handle *handle,
					 void *priv);
void *scmi_notification_instance_data_get(const struct scmi_handle *handle);
int scmi_inflight_count(const struct scmi_handle *handle);
#endif /* _SCMI_COMMON_H */