1 // SPDX-License-Identifier: GPL-2.0
2 #include <asm/byteorder.h>
3 #include "vphn.h"
4 
5 /*
6  * The associativity domain numbers are returned from the hypervisor as a
7  * stream of mixed 16-bit and 32-bit fields. The stream is terminated by the
8  * special value of "all ones" (aka. 0xffff) and its size may not exceed 48
9  * bytes.
10  *
11  *    --- 16-bit fields -->
12  *  _________________________
13  *  |  0  |  1  |  2  |  3  |   be_packed[0]
14  *  ------+-----+-----+------
15  *  _________________________
16  *  |  4  |  5  |  6  |  7  |   be_packed[1]
17  *  -------------------------
18  *            ...
19  *  _________________________
20  *  | 20  | 21  | 22  | 23  |   be_packed[5]
21  *  -------------------------
22  *
23  * Convert to the sequence they would appear in the ibm,associativity property.
24  */
25 int vphn_unpack_associativity(const long *packed, __be32 *unpacked)
26 {
27 	__be64 be_packed[VPHN_REGISTER_COUNT];
28 	int i, nr_assoc_doms = 0;
29 	const __be16 *field = (const __be16 *) be_packed;
30 	u16 last = 0;
31 	bool is_32bit = false;
32 
33 #define VPHN_FIELD_UNUSED	(0xffff)
34 #define VPHN_FIELD_MSB		(0x8000)
35 #define VPHN_FIELD_MASK		(~VPHN_FIELD_MSB)
36 
37 	/* Let's fix the values returned by plpar_hcall9() */
38 	for (i = 0; i < VPHN_REGISTER_COUNT; i++)
39 		be_packed[i] = cpu_to_be64(packed[i]);
40 
41 	for (i = 1; i < VPHN_ASSOC_BUFSIZE; i++) {
42 		u16 new = be16_to_cpup(field++);
43 
44 		if (is_32bit) {
45 			/*
46 			 * Let's concatenate the 16 bits of this field to the
47 			 * 15 lower bits of the previous field
48 			 */
49 			unpacked[++nr_assoc_doms] =
50 				cpu_to_be32(last << 16 | new);
51 			is_32bit = false;
52 		} else if (new == VPHN_FIELD_UNUSED)
53 			/* This is the list terminator */
54 			break;
55 		else if (new & VPHN_FIELD_MSB) {
56 			/* Data is in the lower 15 bits of this field */
57 			unpacked[++nr_assoc_doms] =
58 				cpu_to_be32(new & VPHN_FIELD_MASK);
59 		} else {
60 			/*
61 			 * Data is in the lower 15 bits of this field
62 			 * concatenated with the next 16 bit field
63 			 */
64 			last = new;
65 			is_32bit = true;
66 		}
67 	}
68 
69 	/* The first cell contains the length of the property */
70 	unpacked[0] = cpu_to_be32(nr_assoc_doms);
71 
72 	return nr_assoc_doms;
73 }
74