xref: /illumos-gate/usr/src/uts/intel/sys/amdzen/smn.h (revision 92101ea43dccf9afc9af34c02a30de381d3fe66a)
1 /*
2  * This file and its contents are supplied under the terms of the
3  * Common Development and Distribution License ("CDDL"), version 1.0.
4  * You may only use this file in accordance with the terms of version
5  * 1.0 of the CDDL.
6  *
7  * A full copy of the text of the CDDL should have accompanied this
8  * source.  A copy of the CDDL is also available via the Internet at
9  * http://www.illumos.org/license/CDDL.
10  */
11 
12 /*
13  * Copyright 2023 Oxide Computer Co.
14  */
15 
16 #ifndef _SYS_AMDZEN_SMN_H
17 #define	_SYS_AMDZEN_SMN_H
18 
19 #include <sys/debug.h>
20 #include <sys/sysmacros.h>
21 #include <sys/types.h>
22 
23 /*
24  * Generic definitions for the system management network (SMN) in Milan and many
25  * other AMD Zen processors.  These are shared between the amdzen nexus and its
26  * client drivers and kernel code that may require SMN access to resources.
27  *
28  * ------------------------
29  * Endpoints and Addressing
30  * ------------------------
31  *
32  * SMN addresses are 36 bits long but in practice we can use only 32.  Bits
33  * [35:32] identify a destination node, but all consumers instead direct SMN
34  * transactions to a specific node by selecting the address/data register pair
35  * in the NBIO PCI config space corresponding to the destination.  Additional
36  * information about nodes and the organisation of devices in the Zen
37  * architecture may be found in the block comments in amdzen.c and cpuid.c.
38  *
39  * The SMN provides access to instances of various functional units present on
40  * or accessed via each node.  Some functional units have only a single instance
41  * per node while others may have many.  Each functional unit instance has one
42  * or more apertures in which it decodes addresses.  The aperture portion of the
43  * address consists of bits [31:20] and the remainder of the address is used to
44  * specify a register instance within that functional unit.  To complicate
45  * matters, some functional units have multiple smaller sub-units that decode
46  * smaller regions within its parent's aperture; in some cases, the bits in a
47  * mask describing the sub-unit's registers may not be contiguous.  To keep
48  * software relatively simple, we generally treat sub-units and parent units the
49  * same and try to choose collections of registers whose addresses can all be
50  * computed in the same manner to form what we will describe as a unit.
51  *
52  * Each functional unit should typically have its own header containing register
53  * definitions, accessors, and address calculation routines; some functional
54  * units are small and straightforward while others may have numerous complex
55  * sub-units, registers with many instances whose locations are computed in
56  * unusual and nonstandard ways, and other features that need to be declared for
57  * consumers.  Those functional units that are present across many processors
58  * and have similar or identical contents across them should live in this
59  * directory; umc.h is such an example.  Others may be specific to a particular
60  * processor family (see cpuid.c) or other collection and may require their own
61  * subdirectories, symbol prefixes, and so on.  Unlike the DF, the existence,
62  * location, and format of registers accessible over SMN are not versioned nor
63  * are they generally self-discoverable.  Each functional unit may be present or
64  * absent, in varying numbers and with varying functionality, across the entire
65  * Zen product range.  Therefore, at this time most per-unit headers are
66  * intended for use only by code that will execute on a specific processor
67  * family.  Unifying them over time is considered desirable to the extent the
68  * hardware allows it.
69  *
70  * -----
71  * Types
72  * -----
73  *
74  * Practically every last one of us has screwed up the order of arguments to
75  * functions like amdzen_smn_write32() when they take an address and a value of
76  * the same type.  Repeatedly.  Often.  To safety this particularly annoying
77  * footgun, we pass SMN register addresses around in a dedicated struct type
78  * smn_reg_t, intended to be instantiated only by the amdzen_xx_smn_reg() and
79  * analogous kernel functions and the macros that expand to them or, for the
80  * YOLO crew, SMN_MAKE_REG().  Since the struct type and uint32_t are not
81  * compatible, the compiler will always squawk if the register and value
82  * arguments are reversed, leaving us far fewer baffling failures to debug at
83  * runtime.  Typical callers don't require any awareness of this at all, but
84  * those that want to pass the address around to e.g. log warnings can obtain
85  * the uint32_t address via SMN_REG_ADDR().
86  *
87  * Register definitions within functional units are provided by objects of type
88  * `const smn_reg_def_t`, the usage of which is described in detail in the next
89  * section.  For now these are produced on demand by macros; see additional
90  * notes on conventions below.  In time, this mechanism may be extended to
91  * incorporate version information in a manner similar to that used in df.h.  An
92  * automated mechanism for creating a single collection of register and field
93  * definitions for C, in CTF, and/or for other language consumers as well as
94  * automated register value decoding remains an open area for future work.
95  *
96  * -----------------------
97  * Instances and Iterators
98  * -----------------------
99  *
100  * Not only do some functional units have many instances, so too do many
101  * registers.  AMD documentation describes registers in terms of a series of
102  * iterators over various functional units, subunits, and other entities and
103  * attributes that each multiply the number of register instances.  A concrete
104  * example from the publicly-available Naples PPR (publication 54945 rev. 1.14)
105  * may make this simpler to understand.  Unfortunately, SMN is not described by
106  * this document, but the register instance syntax used is the same and is
107  * described in additional detail in sections 1.3.3-4.  For our example, let us
108  * consider the same MSR that AMD uses in their own example,
109  * Core::X86::MSR::TSC.  We are given that this register has the following
110  * instances: lthree[1:0]_core[3:0]_thread[1:0].  We therefore have three
111  * iterators: one for 'lthree's, one for 'core's for each 'lthree', and one for
112  * 'thread's for each 'core'.  We can also see that there are 16 total
113  * instances; in fact, there are actually 16 per core-complex die (CCD), which
114  * documents for more recent processors would expose as a fourth iterator.  To
115  * keep things relatively simple, we will assume that there are only 16 per
116  * processor.  If it were possible to access all of these instances via MMIO,
117  * SMN, or some other flat address space (it isn't, as far as we can tell), a
118  * function for computing the address of each instance would require three
119  * parameters.  Let us suppose that this register really were accessible via
120  * SMN; in that case, we would also be provided with a list of instance alias
121  * such as
122  *
123  *	_thread[1:0]_core[7:0]_lthree[1:0]_alias_SMN: THREADREGS[1:0]x0000_0010;
124  *	THREADREGS[1:0]=COREREGS[7:0]x0000_[4,0]000;
125  *	COREREGS[7:0]=L3REGS[1:0]x000[7:0]_5000; L3REGS[1:0]=57[A,6]0_0000
126  *
127  * To compute the address of an instance of this hypothetical register, we would
128  * begin by determining that its top-level functional unit is L3REGS with a base
129  * aperture at 0x5760_0000.  There are two instances of this functional unit (01
130  * and 1) and each subsequent instance is offset 0x40_0000 from the previous.
131  * This allows us to compute the base address of each L3REGS block; a similar
132  * process is then used to compute the base address of each COREREGS block, and
133  * finally the address of each THREADREGS block that contains the register
134  * instance.  In practice, we might choose instead to consider the COREREGS as
135  * our functional unit, with instances at 0x5760_5000, 0x5761_5000, 0x57A0_5000,
136  * and 0x57A1_5000; whether it is useful to do this depends on whether we need
137  * to consider other registers in the L3REGS unit that may not have per-core
138  * blocks or instances but would otherwise be interleaved with these.  This ends
139  * up being something of a judgment call.  Let's suppose we want to consider the
140  * entire L3REGS functional unit and write a function to compute the address of
141  * any register (including our hypothetical TSC) in the subordinate THREADREGS
142  * blocks.  We'll start by adding the new unit to the smn_unit_t enumeration;
143  * let's call it SMN_UNIT_L3REGS_COREREGS since that's the sub-unit level at
144  * which we can uniformly compute register instance addresses.  We have already
145  * determined our base aperture and we know that we have 3 iterators and
146  * therefore three parameters; all SMN address calculators return an smn_reg_t
147  * and must accept an smn_reg_def_t.  Therefore our function's signature is:
148  *
149  * smn_reg_t amdzen_smn_l3regs_coreregs_reg(uint8_t l3no,
150  *     const smn_reg_def_t def, uint16_t coreinst, uint16_t threadinst);
151  *
152  * We have chosen to use a base aperture of 0x5760_0000 and unit offset
153  * 0x40_0000, so we can begin by computing a COREREGS aperture:
154  *
155  * const uint32_t aperture_base = 0x57600000;
156  * const uint32_t aperture_off = l3no * 0x400000;
157  * const uint32_t coreregs_aperture_base = 0x5000;
158  * const uint32_t coreregs_aperture_off = coreinst * 0x10000;
159  *
160  * We can now consider the smn_reg_def_t our function will be given, which
161  * describes THREADREGS::TSC.  Within the COREREGS functional sub-unit, each
162  * thread register has 2 instances present at a stride of 0x4000 bytes (from our
163  * hypothetical register definition), so the register would be defined as
164  * follows:
165  *
166  * #define	D_L3REGS_COREREGS_THREAD_TSC	(const smn_reg_def_t){	\
167  *	.srd_unit = SMN_UNIT_L3REGS_COREREGS,	\
168  *	.srd_reg = 0x10,	\
169  *	.srd_nents = 2,	\
170  *	.srd_stride = 0x4000	\
171  * }
172  *
173  * Note that describing the number of entries and their stride in the register
174  * definition allows us to collapse the last functional sub-unit in our
175  * calculation process: we need not compute the base aperture address of the
176  * THREADREGS sub-unit.  Instead, we can follow our previous code with:
177  *
178  * const uint32_t aperture = aperture_base +
179  *     coreregs_aperture_base + coreregs_aperture_off;
180  * const uint32_t reg = def.srd_reg + threadinst * def.srd_stride;
181  *
182  * Finally, we convert the aperture address and register offset into the
183  * appropriate type and return it:
184  *
185  * return (SMN_MAKE_REG(aperture + reg));
186  *
187  * As you can see, other registers in THREADREGS would be defined with the same
188  * number entries and stride but a different offset (srd_reg member), while
189  * other registers in the COREREGS block would have a different offset and
190  * stride.  For example, if a block of per-core (not per-thread) registers were
191  * located at COREREGS[7:0]x0000_1000, a register called "COREREGS::FrobberCntl"
192  * in that block with a single instance at offset 0x48 might be defined as
193  *
194  * #define	D_L3REGS_COREREGS_FROB_CTL	(const smn_reg_def_t){	\
195  *	.srd_unit = SMN_UNIT_L3REGS_COREREGS,	\
196  *	.srd_reg = 0x1048,	\
197  *	.srd_nents = 1	\
198  * }
199  *
200  * You can satisfy yourself that the same calculation function we wrote above
201  * will correctly compute the address of the sole instance (0) of this register.
202  * To further simplify register definitions and callers, the actual address
203  * calculation functions are written to treat srd_nents == 0 to mean a register
204  * with a single instance, and to treat srd_stride == 0 as if it were 4 (the
205  * space occupied by registers accessed by SMN is -- so far as we can tell,
206  * practically always -- 4 bytes in size, even if the register itself is
207  * smaller).  Additionally, a large number of assertions should be present in
208  * such functions to guard against foreign unit register definitions,
209  * out-of-bounds unit and register instance parameters, address overflow, and
210  * register instance offsets that overflow improperly into an aperture base
211  * address.  All of these conditions indicate either an incorrect register
212  * definition or a bug in the caller.  See the template macro at the bottom of
213  * this file and umc.h for additional examples of calculating and checking
214  * register addresses.
215  *
216  * With address computation out of the way, we can then provide an accessor for
217  * each instance this register:
218  *
219  * #define	L3REGS_COREREGS_THREAD_TSC(l3, core, thread)	\
220  *	amdzen_l3regs_coreregs_reg(l3, D_L3REGS_COREREGS_THREAD_TSC, \
221  *	core, thread)
222  *
223  * Our other per-core register's accessor would look like:
224  *
225  * #define	L3REGS_COREREGS_FROB_CTL(l3, core)	\
226  *	amdzen_l3regs_coreregs_reg(l3, D_L3REGS_COREREGS_FROB_CTL, core, 0)
227  *
228  * The next section describes these conventions in greater detail.
229  *
230  * -----------
231  * Conventions
232  * -----------
233  *
234  * First, let's consider the names of the register definition and the
235  * convenience macro supplied to obtain an instance of that register: we've
236  * prefixed the global definition of the registers with D_ and the convenience
237  * macros to return a specific instance are simply named for the register
238  * itself.  Additionally, the two macros expand to objects of incompatible
239  * types, so that using the wrong one will always be detected at compile time.
240  * Why do we expose both of these?  The instance macro is useful for callers who
241  * know at compile-time the name of the register of which they want instances;
242  * this makes it unnecessary to remember the names of functions used to compute
243  * register instance addresses.  The definition itself is useful to callers that
244  * accept const smn_reg_def_t arguments referring to registers of which the
245  * immediate caller does not know the names at compile time.
246  *
247  * You may wonder why we don't declare named constants for the definitions.
248  * There are two ways we could do that and both are unfortunate: one would be to
249  * declare them static in the header, the other to separate declarations in the
250  * header from initialisation in a separate source file.  Measurements revealed
251  * that the former causes a very substantial increase in data size, which will
252  * be multiplied by the number of registers defined and the number of source
253  * files including the header.  As convenient as it is to have these symbolic
254  * constants available to debuggers and other tools at runtime, they're just too
255  * big.  However, it is possible to generate code to be compiled into loadable
256  * modules that would contain a single copy of the constants for this purpose as
257  * well as for providing CTF to foreign-language binding generators.  The other
258  * option considered here, putting the constants in separate source files, makes
259  * maintenance significantly more challenging and makes it likely not only that
260  * new registers may not be added properly but also that definitions, macros, or
261  * both may be incorrect.  Neither of these options is terrible but for now
262  * we've optimised for simplicity of maintenance and minimal data size at the
263  * immediate but not necessarily permanent expense of some debugging
264  * convenience.
265  *
266  * We wish to standardise as much as possible on conventions across all
267  * Zen-related functional units and blocks (including those accessed by SMN,
268  * through the DF directly, and by other means).  In general, some register and
269  * field names are shortened from their official names for clarity and brevity;
270  * the official names are always given in the comment above the definition.
271  * AMD's functional units come from many internal teams and presumably several
272  * outside vendors as well; as a result, there is no single convention to be
273  * found throughout the PPRs and other documentation.  For example, different
274  * units may have registers containing "CTL", "CNTL", "CTRL", "CNTRL", and
275  * "CONTROL", as well as "FOO_CNTL", "FooCntl", and "Foo_Cntl".  Reflecting
276  * longstanding illumos conventions, we collapse all such register names
277  * regardless of case as follows:
278  *
279  * CTL/CTRL/CNTL/CNTRL/CONTROL				=> CTL
280  * CFG/CONF/CONFIG/CONFIGURATION			=> CFG
281  * EN/ENAB/ENABLE/ENABLED				=> EN
282  * DIS/DISAB/DISABLE/DISABLED				=> DIS
283  *
284  * Note that if collapsing these would result in ambiguity, more of the official
285  * names will be preserved.  In addition to collapsing register and field names
286  * in this case-insensitive manner, we also follow standard code style practice
287  * and name macros and constants in SCREAMING_SNAKE_CASE regardless of AMD's
288  * official name.  It is similarly reasonable to truncate or abbreviate other
289  * common terms in a consistent manner where doing so preserves uniqueness and
290  * at least some semantic value; without doing so, some official register names
291  * will be excessively unwieldy and may not even fit into 80 columns.  Please
292  * maintain these practices and strive for consistency with existing examples
293  * when abbreviation is required.
294  *
295  * As we have done elsewhere throughout the amdzen body of work, register fields
296  * should always be given in order starting with the most significant bits and
297  * working down toward 0; this matches AMD's documentation and makes it easier
298  * for reviewers and other readers to follow.  The routines in bitext.h should
299  * be used to extract and set bitfields unless there is a compelling reason to
300  * do otherwise (e.g., assembly consumers).  Accessors should be named
301  * UNIT_REG_GET_FIELD and UNIT_REG_SET_FIELD respectively, unless the register
302  * has a single field that has no meaningful name (i.e., the field's name is the
303  * same as the register's or it's otherwise obvious from the context what its
304  * purpose is), in which case UNIT_REG_GET and UNIT_REG_SET are appropriate.
305  * Additional getters and setters that select a particular bit from a register
306  * or field consisting entirely of individual bits describing or controlling the
307  * state of some entity may also be useful.  As with register names, be as brief
308  * as possible without sacrificing too much information.
309  *
310  * Constant values associated with a field should be declared immediately
311  * following that field.  If a constant or collection of constants is used in
312  * multiple fields of the same register, the definitions should follow the last
313  * such field; similarly, constants used in multiple registers should follow the
314  * last such register, and a comment explaining the scope of their validity is
315  * recommended.  Such constants should be named for the common elements of the
316  * fields or registers in which they are valid.
317  *
318  * As noted above, SMN register definitions should omit the srd_nents and
319  * srd_stride members when there is a single instance of the register within the
320  * unit.  The srd_stride member should also be elided when the register
321  * instances are contiguous.  All address calculation routines should be written
322  * to support these conventions.  Each register should have an accessor macro or
323  * function, and should accept instance numbers in order from superior to
324  * inferior (e.g., from the largest functional unit to the smallest, ending with
325  * the register instance itself).  This convention is similar to that used in
326  * generic PCIe code in which a register is specified by bus, device, and
327  * function numbers in that order.  Register accessor macros or inline functions
328  * should not expose inapplicable taxons to callers; in our example above,
329  * COREREGS_FROB_CTL has an instance for each core but is not associated with a
330  * thread; therefore its accessor should not accept a thread instance argument
331  * even though the address calculation function it uses does.
332  *
333  * Most of these conventions are not specific to registers accessed via SMN;
334  * note also that some registers may be accessed in multiple ways (e.g., SMN and
335  * MMIO, or SMN and the MSR instructions).  While the code here is generally
336  * unaware of such aliased access methods, following these conventions will
337  * simplify naming and usage if such a register needs to be accessed in multiple
338  * ways.  Sensible additions to macro and symbol names such as the access method
339  * to be used will generally be sufficient to disambiguate while allowing reuse
340  * of associated field accessors, constants, and in some cases even register
341  * offset, instance count, and stride.
342  */
343 
344 #ifdef __cplusplus
345 extern "C" {
346 #endif
347 
348 #define	SMN_APERTURE_MASK	0xfff00000
349 
350 /*
351  * An instance of an SMN-accessible register.
352  */
353 typedef struct smn_reg {
354 	uint32_t sr_addr;
355 	uint8_t sr_size;	/* Not size_t: can't ever be that big. */
356 } smn_reg_t;
357 
358 /*
359  * These are intended to be macro-like (and indeed some used to be macros) but
360  * are implemented as inline functions so that we can use compound statements
361  * without extensions and don't have to worry about multiple evaluation.  Hence
362  * their capitalised names.
363  */
364 static inline smn_reg_t
365 SMN_MAKE_REG_SIZED(const uint32_t addr, const uint8_t size)
366 {
367 	const uint8_t size_always = (size == 0) ? 4 : size;
368 	const smn_reg_t rv = {
369 	    .sr_addr = addr,
370 	    .sr_size = size_always
371 	};
372 
373 	return (rv);
374 }
375 
376 #define	SMN_MAKE_REG(x)		SMN_MAKE_REG_SIZED(x, 4)
377 #define	SMN_REG_ADDR(x)		((x).sr_addr)
378 #define	SMN_REG_SIZE(x)		((x).sr_size)
379 
380 static inline boolean_t
381 SMN_REG_SIZE_IS_VALID(const smn_reg_t reg)
382 {
383 	return (reg.sr_size == 1 || reg.sr_size == 2 || reg.sr_size == 4);
384 }
385 
386 /* Is this register suitably aligned for access of <size> bytes? */
387 #define	SMN_REG_IS_ALIGNED(x, size)	IS_P2ALIGNED(SMN_REG_ADDR(x), size)
388 
389 /* Is this register naturally aligned with respect to its own width? */
390 static inline boolean_t
391 SMN_REG_IS_NATURALLY_ALIGNED(const smn_reg_t reg)
392 {
393 	return (SMN_REG_IS_ALIGNED(reg, reg.sr_size));
394 }
395 
396 /* Does <val> fit into SMN register <x>? */
397 #define	SMN_REG_VALUE_FITS(x, val)	\
398 	(((val) & ~(0xffffffffU >> ((4 - SMN_REG_SIZE(x)) << 3))) == 0)
399 
400 /*
401  * Retrieve the base address of the register.  This is the address that will
402  * actually be set in the index register when performing a read or write of the
403  * underlying register via SMN.  It must always be 32-bit aligned.
404  */
405 static inline uint32_t
406 SMN_REG_ADDR_BASE(const smn_reg_t reg)
407 {
408 	return (reg.sr_addr & ~3);
409 }
410 
411 /*
412  * The offset address is the byte offset into the 32-bit-wide data register that
413  * will be returned by a read or set by a write, if the register is smaller than
414  * 32 bits wide.  For registers that are 32 bits wide, this is always 0.
415  */
416 static inline uint32_t
417 SMN_REG_ADDR_OFF(const smn_reg_t reg)
418 {
419 	return (reg.sr_addr & 3);
420 }
421 
422 /*
423  * This exists so that address calculation functions can check that the register
424  * definitions they're passed are something they understand how to use.  While
425  * many address calculation functions are similar, some functional units define
426  * registers with multiple iterators, have differently-sized apertures, or both;
427  * it's important that we reject foreign register definitions in these
428  * functions.  In principle this could be done at compile time, but the
429  * preprocessor gymnastics required to do so are excessively vile and we are
430  * really already hanging it pretty far over the edge in terms of what the C
431  * preprocessor can do for us.
432  */
433 typedef enum smn_unit {
434 	SMN_UNIT_UNKNOWN,
435 	SMN_UNIT_IOAPIC,
436 	SMN_UNIT_IOHC,
437 	SMN_UNIT_IOHCDEV_PCIE,
438 	SMN_UNIT_IOHCDEV_NBIF,
439 	SMN_UNIT_IOHCDEV_SB,
440 	SMN_UNIT_IOAGR,
441 	SMN_UNIT_SDPMUX,
442 	SMN_UNIT_UMC,
443 	SMN_UNIT_PCIE_CORE,
444 	SMN_UNIT_PCIE_PORT,
445 	SMN_UNIT_PCIE_RSMU,
446 	SMN_UNIT_SCFCTP,
447 	SMN_UNIT_SMUPWR,
448 	SMN_UNIT_IOMMUL1,
449 	SMN_UNIT_IOMMUL2,
450 	SMN_UNIT_NBIF,
451 	SMN_UNIT_NBIF_ALT,
452 	SMN_UNIT_NBIF_FUNC
453 } smn_unit_t;
454 
455 /*
456  * srd_unit and srd_reg are required; they describe the functional unit and the
457  * register's address within that unit's aperture (which may be the SDP-defined
458  * aperture described above or a smaller one if a unit has been broken down
459  * logically into smaller units).  srd_nents is optional; if not set, all
460  * existing consumers assume a value of 0 is equivalent to 1: the register has
461  * but a single instance in each unit.  srd_size is the width of the register in
462  * bytes, which must be 0, 1, 2, or 4.  If 0, the size is assumed to be 4 bytes.
463  * srd_stride is ignored if srd_nents is 0 or 1 and optional otherwise; it
464  * describes the number of bytes to be added to the previous instance's address
465  * to obtain that of the next instance.  If left at 0 it is assumed to be equal
466  * to the width of the register.
467  *
468  * There are units in which registers have more complicated collections of
469  * instances that cannot be represented perfectly by this simple descriptor;
470  * they require custom address calculation macros and functions that may take
471  * additional arguments, and they may not be able to check their arguments or
472  * the computed addresses as carefully as would be ideal.
473  */
474 typedef struct smn_reg_def {
475 	smn_unit_t	srd_unit;
476 	uint32_t	srd_reg;
477 	uint32_t	srd_stride;
478 	uint16_t	srd_nents;
479 	uint8_t		srd_size;
480 } smn_reg_def_t;
481 
482 /*
483  * This macro may be used by per-functional-unit code to construct an address
484  * calculation function.  It is usable by some, BUT NOT ALL, functional units;
485  * see the block comment above for an example that cannot be accommodated.  Here
486  * we assume that there are at most 2 iterators in any register's definition.
487  * Use this when possible, as it provides a large number of useful checks on
488  * DEBUG bits.  Similar checks should be incorporated into implementations for
489  * nonstandard functional units to the extent possible.
490  */
491 
492 #define	AMDZEN_MAKE_SMN_REG_FN(_fn, _unit, _base, _mask, _nunits, _unitshift) \
493 CTASSERT(((_base) & ~(_mask)) == 0);					\
494 static inline smn_reg_t							\
495 _fn(const uint8_t unitno, const smn_reg_def_t def, const uint16_t reginst) \
496 {									\
497 	const uint32_t unit32 = (const uint32_t)unitno;			\
498 	const uint32_t reginst32 = (const uint32_t)reginst;		\
499 	const uint32_t size32 = (def.srd_size == 0) ? 4 :		\
500 	    (const uint32_t)def.srd_size;				\
501 	ASSERT(size32 == 1 || size32 == 2 || size32 == 4);		\
502 	const uint32_t stride = (def.srd_stride == 0) ? size32 :	\
503 	    def.srd_stride;						\
504 	ASSERT3U(stride, >=, size32);					\
505 	const uint32_t nents = (def.srd_nents == 0) ? 1 :		\
506 	    (const uint32_t)def.srd_nents;				\
507 									\
508 	ASSERT3S(def.srd_unit, ==, SMN_UNIT_ ## _unit);			\
509 	ASSERT3U(unit32, <, (_nunits));					\
510 	ASSERT3U(nents, >, reginst32);					\
511 	ASSERT0(def.srd_reg & (_mask));					\
512 									\
513 	const uint32_t aperture_base = (_base);				\
514 									\
515 	const uint32_t aperture_off = (unit32 << (_unitshift));		\
516 	ASSERT3U(aperture_off, <=, UINT32_MAX - aperture_base);		\
517 									\
518 	const uint32_t aperture = aperture_base + aperture_off;		\
519 	ASSERT0(aperture & ~(_mask));					\
520 									\
521 	const uint32_t reg = def.srd_reg + reginst32 * stride;		\
522 	ASSERT0(reg & (_mask));						\
523 									\
524 	return (SMN_MAKE_REG_SIZED(aperture + reg, size32));		\
525 }
526 
527 /*
528  * An invalid SMN read will return all 1s similar to PCI.
529  */
530 #define	SMN_EINVAL32	0xffffffff
531 
532 #ifdef __cplusplus
533 }
534 #endif
535 
536 #endif /* _SYS_AMDZEN_SMN_H */
537