protocols.h

  1/* SPDX-License-Identifier: GPL-2.0 */
  2/*
  3 * System Control and Management Interface (SCMI) Message Protocol
  4 * protocols common header file containing some definitions, structures
  5 * and function prototypes used in all the different SCMI protocols.
  6 *
  7 * Copyright (C) 2022 ARM Ltd.
  8 */
  9#ifndef _SCMI_PROTOCOLS_H
 10#define _SCMI_PROTOCOLS_H
 11
 12#include <linux/bitfield.h>
 13#include <linux/completion.h>
 14#include <linux/device.h>
 15#include <linux/errno.h>
 16#include <linux/kernel.h>
 17#include <linux/hashtable.h>
 18#include <linux/list.h>
 19#include <linux/module.h>
 20#include <linux/refcount.h>
 21#include <linux/scmi_protocol.h>
 22#include <linux/spinlock.h>
 23#include <linux/types.h>
 24
 25#include <linux/unaligned.h>
 26
 27#define PROTOCOL_REV_MINOR_MASK	GENMASK(15, 0)
 28#define PROTOCOL_REV_MAJOR_MASK	GENMASK(31, 16)
 29#define PROTOCOL_REV_MAJOR(x)	((u16)(FIELD_GET(PROTOCOL_REV_MAJOR_MASK, (x))))
 30#define PROTOCOL_REV_MINOR(x)	((u16)(FIELD_GET(PROTOCOL_REV_MINOR_MASK, (x))))
 31
 32#define SCMI_PROTOCOL_VENDOR_BASE	0x80
 33
 34#define MSG_SUPPORTS_FASTCHANNEL(x)	((x) & BIT(0))
 35
 36enum scmi_common_cmd {
 37	PROTOCOL_VERSION = 0x0,
 38	PROTOCOL_ATTRIBUTES = 0x1,
 39	PROTOCOL_MESSAGE_ATTRIBUTES = 0x2,
 40	NEGOTIATE_PROTOCOL_VERSION = 0x10,
 41};
 42
 43/**
 44 * struct scmi_msg_resp_prot_version - Response for a message
 45 *
 46 * @minor_version: Minor version of the ABI that firmware supports
 47 * @major_version: Major version of the ABI that firmware supports
 48 *
 49 * In general, ABI version changes follow the rule that minor version increments
 50 * are backward compatible. Major revision changes in ABI may not be
 51 * backward compatible.
 52 *
 53 * Response to a generic message with message type SCMI_MSG_VERSION
 54 */
 55struct scmi_msg_resp_prot_version {
 56	__le16 minor_version;
 57	__le16 major_version;
 58};
 59
 60/**
 61 * struct scmi_msg - Message(Tx/Rx) structure
 62 *
 63 * @buf: Buffer pointer
 64 * @len: Length of data in the Buffer
 65 */
 66struct scmi_msg {
 67	void *buf;
 68	size_t len;
 69};
 70
 71/**
 72 * struct scmi_msg_hdr - Message(Tx/Rx) header
 73 *
 74 * @id: The identifier of the message being sent
 75 * @protocol_id: The identifier of the protocol used to send @id message
 76 * @type: The SCMI type for this message
 77 * @seq: The token to identify the message. When a message returns, the
 78 *	platform returns the whole message header unmodified including the
 79 *	token
 80 * @status: Status of the transfer once it's complete
 81 * @poll_completion: Indicate if the transfer needs to be polled for
 82 *	completion or interrupt mode is used
 83 */
 84struct scmi_msg_hdr {
 85	u8 id;
 86	u8 protocol_id;
 87	u8 type;
 88	u16 seq;
 89	u32 status;
 90	bool poll_completion;
 91};
 92
 93/**
 94 * struct scmi_xfer - Structure representing a message flow
 95 *
 96 * @transfer_id: Unique ID for debug & profiling purpose
 97 * @hdr: Transmit message header
 98 * @tx: Transmit message
 99 * @rx: Receive message, the buffer should be pre-allocated to store
100 *	message. If request-ACK protocol is used, we can reuse the same
101 *	buffer for the rx path as we use for the tx path.
102 * @done: command message transmit completion event
103 * @async_done: pointer to delayed response message received event completion
104 * @pending: True for xfers added to @pending_xfers hashtable
105 * @node: An hlist_node reference used to store this xfer, alternatively, on
106 *	  the free list @free_xfers or in the @pending_xfers hashtable
107 * @users: A refcount to track the active users for this xfer.
108 *	   This is meant to protect against the possibility that, when a command
109 *	   transaction times out concurrently with the reception of a valid
110 *	   response message, the xfer could be finally put on the TX path, and
111 *	   so vanish, while on the RX path scmi_rx_callback() is still
112 *	   processing it: in such a case this refcounting will ensure that, even
113 *	   though the timed-out transaction will anyway cause the command
114 *	   request to be reported as failed by time-out, the underlying xfer
115 *	   cannot be discarded and possibly reused until the last one user on
116 *	   the RX path has released it.
117 * @busy: An atomic flag to ensure exclusive write access to this xfer
118 * @state: The current state of this transfer, with states transitions deemed
119 *	   valid being:
120 *	    - SCMI_XFER_SENT_OK -> SCMI_XFER_RESP_OK [ -> SCMI_XFER_DRESP_OK ]
121 *	    - SCMI_XFER_SENT_OK -> SCMI_XFER_DRESP_OK
122 *	      (Missing synchronous response is assumed OK and ignored)
123 * @flags: Optional flags associated to this xfer.
124 * @lock: A spinlock to protect state and busy fields.
125 * @priv: A pointer for transport private usage.
126 */
127struct scmi_xfer {
128	int transfer_id;
129	struct scmi_msg_hdr hdr;
130	struct scmi_msg tx;
131	struct scmi_msg rx;
132	struct completion done;
133	struct completion *async_done;
134	bool pending;
135	struct hlist_node node;
136	refcount_t users;
137#define SCMI_XFER_FREE		0
138#define SCMI_XFER_BUSY		1
139	atomic_t busy;
140#define SCMI_XFER_SENT_OK	0
141#define SCMI_XFER_RESP_OK	1
142#define SCMI_XFER_DRESP_OK	2
143	int state;
144#define SCMI_XFER_FLAG_IS_RAW	BIT(0)
145#define SCMI_XFER_IS_RAW(x)	((x)->flags & SCMI_XFER_FLAG_IS_RAW)
146#define SCMI_XFER_FLAG_CHAN_SET	BIT(1)
147#define SCMI_XFER_IS_CHAN_SET(x)	\
148	((x)->flags & SCMI_XFER_FLAG_CHAN_SET)
149	int flags;
150	/* A lock to protect state and busy fields */
151	spinlock_t lock;
152	void *priv;
153};
154
155struct scmi_xfer_ops;
156struct scmi_proto_helpers_ops;
157
158/**
159 * struct scmi_protocol_handle  - Reference to an initialized protocol instance
160 *
161 * @dev: A reference to the associated SCMI instance device (handle->dev).
162 * @xops: A reference to a struct holding refs to the core xfer operations that
163 *	  can be used by the protocol implementation to generate SCMI messages.
164 * @set_priv: A method to set protocol private data for this instance.
165 * @get_priv: A method to get protocol private data previously set.
166 *
167 * This structure represents a protocol initialized against specific SCMI
168 * instance and it will be used as follows:
169 * - as a parameter fed from the core to the protocol initialization code so
170 *   that it can access the core xfer operations to build and generate SCMI
171 *   messages exclusively for the specific underlying protocol instance.
172 * - as an opaque handle fed by an SCMI driver user when it tries to access
173 *   this protocol through its own protocol operations.
174 *   In this case this handle will be returned as an opaque object together
175 *   with the related protocol operations when the SCMI driver tries to access
176 *   the protocol.
177 */
178struct scmi_protocol_handle {
179	struct device *dev;
180	const struct scmi_xfer_ops *xops;
181	const struct scmi_proto_helpers_ops *hops;
182	int (*set_priv)(const struct scmi_protocol_handle *ph, void *priv,
183			u32 version);
184	void *(*get_priv)(const struct scmi_protocol_handle *ph);
185};
186
187/**
188 * struct scmi_iterator_state  - Iterator current state descriptor
189 * @desc_index: Starting index for the current mulit-part request.
190 * @num_returned: Number of returned items in the last multi-part reply.
191 * @num_remaining: Number of remaining items in the multi-part message.
192 * @max_resources: Maximum acceptable number of items, configured by the caller
193 *		   depending on the underlying resources that it is querying.
194 * @loop_idx: The iterator loop index in the current multi-part reply.
195 * @rx_len: Size in bytes of the currenly processed message; it can be used by
196 *	    the user of the iterator to verify a reply size.
197 * @priv: Optional pointer to some additional state-related private data setup
198 *	  by the caller during the iterations.
199 */
200struct scmi_iterator_state {
201	unsigned int desc_index;
202	unsigned int num_returned;
203	unsigned int num_remaining;
204	unsigned int max_resources;
205	unsigned int loop_idx;
206	size_t rx_len;
207	void *priv;
208};
209
210/**
211 * struct scmi_iterator_ops  - Custom iterator operations
212 * @prepare_message: An operation to provide the custom logic to fill in the
213 *		     SCMI command request pointed by @message. @desc_index is
214 *		     a reference to the next index to use in the multi-part
215 *		     request.
216 * @update_state: An operation to provide the custom logic to update the
217 *		  iterator state from the actual message response.
218 * @process_response: An operation to provide the custom logic needed to process
219 *		      each chunk of the multi-part message.
220 */
221struct scmi_iterator_ops {
222	void (*prepare_message)(void *message, unsigned int desc_index,
223				const void *priv);
224	int (*update_state)(struct scmi_iterator_state *st,
225			    const void *response, void *priv);
226	int (*process_response)(const struct scmi_protocol_handle *ph,
227				const void *response,
228				struct scmi_iterator_state *st, void *priv);
229};
230
231struct scmi_fc_db_info {
232	int width;
233	u64 set;
234	u64 mask;
235	void __iomem *addr;
236};
237
238struct scmi_fc_info {
239	void __iomem *set_addr;
240	void __iomem *get_addr;
241	struct scmi_fc_db_info *set_db;
242	u32 rate_limit;
243};
244
245/**
246 * struct scmi_proto_helpers_ops  - References to common protocol helpers
247 * @extended_name_get: A common helper function to retrieve extended naming
248 *		       for the specified resource using the specified command.
249 *		       Result is returned as a NULL terminated string in the
250 *		       pre-allocated area pointed to by @name with maximum
251 *		       capacity of @len bytes.
252 * @iter_response_init: A common helper to initialize a generic iterator to
253 *			parse multi-message responses: when run the iterator
254 *			will take care to send the initial command request as
255 *			specified by @msg_id and @tx_size and then to parse the
256 *			multi-part responses using the custom operations
257 *			provided in @ops.
258 * @iter_response_run: A common helper to trigger the run of a previously
259 *		       initialized iterator.
260 * @protocol_msg_check: A common helper to check is a specific protocol message
261 *			is supported.
262 * @fastchannel_init: A common helper used to initialize FC descriptors by
263 *		      gathering FC descriptions from the SCMI platform server.
264 * @fastchannel_db_ring: A common helper to ring a FC doorbell.
265 * @get_max_msg_size: A common helper to get the maximum message size.
266 */
267struct scmi_proto_helpers_ops {
268	int (*extended_name_get)(const struct scmi_protocol_handle *ph,
269				 u8 cmd_id, u32 res_id, u32 *flags, char *name,
270				 size_t len);
271	void *(*iter_response_init)(const struct scmi_protocol_handle *ph,
272				    struct scmi_iterator_ops *ops,
273				    unsigned int max_resources, u8 msg_id,
274				    size_t tx_size, void *priv);
275	int (*iter_response_run)(void *iter);
276	int (*protocol_msg_check)(const struct scmi_protocol_handle *ph,
277				  u32 message_id, u32 *attributes);
278	void (*fastchannel_init)(const struct scmi_protocol_handle *ph,
279				 u8 describe_id, u32 message_id,
280				 u32 valid_size, u32 domain,
281				 void __iomem **p_addr,
282				 struct scmi_fc_db_info **p_db,
283				 u32 *rate_limit);
284	void (*fastchannel_db_ring)(struct scmi_fc_db_info *db);
285	int (*get_max_msg_size)(const struct scmi_protocol_handle *ph);
286};
287
288/**
289 * struct scmi_xfer_ops  - References to the core SCMI xfer operations.
290 * @version_get: Get this version protocol.
291 * @xfer_get_init: Initialize one struct xfer if any xfer slot is free.
292 * @reset_rx_to_maxsz: Reset rx size to max transport size.
293 * @do_xfer: Do the SCMI transfer.
294 * @do_xfer_with_response: Do the SCMI transfer waiting for a response.
295 * @xfer_put: Free the xfer slot.
296 *
297 * Note that all this operations expect a protocol handle as first parameter;
298 * they then internally use it to infer the underlying protocol number: this
299 * way is not possible for a protocol implementation to forge messages for
300 * another protocol.
301 */
302struct scmi_xfer_ops {
303	int (*version_get)(const struct scmi_protocol_handle *ph, u32 *version);
304	int (*xfer_get_init)(const struct scmi_protocol_handle *ph, u8 msg_id,
305			     size_t tx_size, size_t rx_size,
306			     struct scmi_xfer **p);
307	void (*reset_rx_to_maxsz)(const struct scmi_protocol_handle *ph,
308				  struct scmi_xfer *xfer);
309	int (*do_xfer)(const struct scmi_protocol_handle *ph,
310		       struct scmi_xfer *xfer);
311	int (*do_xfer_with_response)(const struct scmi_protocol_handle *ph,
312				     struct scmi_xfer *xfer);
313	void (*xfer_put)(const struct scmi_protocol_handle *ph,
314			 struct scmi_xfer *xfer);
315};
316
317typedef int (*scmi_prot_init_ph_fn_t)(const struct scmi_protocol_handle *);
318
319/**
320 * struct scmi_protocol  - Protocol descriptor
321 * @id: Protocol ID.
322 * @owner: Module reference if any.
323 * @instance_init: Mandatory protocol initialization function.
324 * @instance_deinit: Optional protocol de-initialization function.
325 * @ops: Optional reference to the operations provided by the protocol and
326 *	 exposed in scmi_protocol.h.
327 * @events: An optional reference to the events supported by this protocol.
328 * @supported_version: The highest version currently supported for this
329 *		       protocol by the agent. Each protocol implementation
330 *		       in the agent is supposed to downgrade to match the
331 *		       protocol version supported by the platform.
332 * @vendor_id: A firmware vendor string for vendor protocols matching.
333 *	       Ignored when @id identifies a standard protocol, cannot be NULL
334 *	       otherwise.
335 * @sub_vendor_id: A firmware sub_vendor string for vendor protocols matching.
336 *		   Ignored if NULL or when @id identifies a standard protocol.
337 * @impl_ver: A firmware implementation version for vendor protocols matching.
338 *	      Ignored if zero or if @id identifies a standard protocol.
339 *
340 * Note that vendor protocols matching at load time is performed by attempting
341 * the closest match first against the tuple (vendor, sub_vendor, impl_ver)
342 */
343struct scmi_protocol {
344	const u8				id;
345	struct module				*owner;
346	const scmi_prot_init_ph_fn_t		instance_init;
347	const scmi_prot_init_ph_fn_t		instance_deinit;
348	const void				*ops;
349	const struct scmi_protocol_events	*events;
350	unsigned int				supported_version;
351	char					*vendor_id;
352	char					*sub_vendor_id;
353	u32					impl_ver;
354};
355
356#define DEFINE_SCMI_PROTOCOL_REGISTER_UNREGISTER(name, proto)	\
357static const struct scmi_protocol *__this_proto = &(proto);	\
358								\
359int __init scmi_##name##_register(void)				\
360{								\
361	return scmi_protocol_register(__this_proto);		\
362}								\
363								\
364void __exit scmi_##name##_unregister(void)			\
365{								\
366	scmi_protocol_unregister(__this_proto);			\
367}
368
369#define DECLARE_SCMI_REGISTER_UNREGISTER(func)		\
370	int __init scmi_##func##_register(void);	\
371	void __exit scmi_##func##_unregister(void)
372DECLARE_SCMI_REGISTER_UNREGISTER(base);
373DECLARE_SCMI_REGISTER_UNREGISTER(clock);
374DECLARE_SCMI_REGISTER_UNREGISTER(perf);
375DECLARE_SCMI_REGISTER_UNREGISTER(pinctrl);
376DECLARE_SCMI_REGISTER_UNREGISTER(power);
377DECLARE_SCMI_REGISTER_UNREGISTER(reset);
378DECLARE_SCMI_REGISTER_UNREGISTER(sensors);
379DECLARE_SCMI_REGISTER_UNREGISTER(voltage);
380DECLARE_SCMI_REGISTER_UNREGISTER(system);
381DECLARE_SCMI_REGISTER_UNREGISTER(powercap);
382
383#endif /* _SCMI_PROTOCOLS_H */