1// SPDX-License-Identifier: GPL-2.0-only
2
3#define pr_fmt(fmt)	"papr-sysparm: " fmt
4
5#include <linux/bug.h>
6#include <linux/init.h>
7#include <linux/kernel.h>
8#include <linux/printk.h>
9#include <linux/slab.h>
10#include <asm/rtas.h>
11#include <asm/papr-sysparm.h>
12#include <asm/rtas-work-area.h>
13
14struct papr_sysparm_buf *papr_sysparm_buf_alloc(void)
15{
16	struct papr_sysparm_buf *buf = kzalloc(sizeof(*buf), GFP_KERNEL);
17
18	return buf;
19}
20
21void papr_sysparm_buf_free(struct papr_sysparm_buf *buf)
22{
23	kfree(buf);
24}
25
26/**
27 * papr_sysparm_get() - Retrieve the value of a PAPR system parameter.
28 * @param: PAPR system parameter token as described in
29 *         7.3.16 "System Parameters Option".
30 * @buf: A &struct papr_sysparm_buf as returned from papr_sysparm_buf_alloc().
31 *
32 * Place the result of querying the specified parameter, if available,
33 * in @buf. The result includes a be16 length header followed by the
34 * value, which may be a string or binary data. See &struct papr_sysparm_buf.
35 *
36 * Since there is at least one parameter (60, OS Service Entitlement
37 * Status) where the results depend on the incoming contents of the
38 * work area, the caller-supplied buffer is copied unmodified into the
39 * work area before calling ibm,get-system-parameter.
40 *
41 * A defined parameter may not be implemented on a given system, and
42 * some implemented parameters may not be available to all partitions
43 * on a system. A parameter's disposition may change at any time due
44 * to system configuration changes or partition migration.
45 *
46 * Context: This function may sleep.
47 *
48 * Return: 0 on success, -errno otherwise. @buf is unmodified on error.
49 */
50
51int papr_sysparm_get(papr_sysparm_t param, struct papr_sysparm_buf *buf)
52{
53	const s32 token = rtas_function_token(RTAS_FN_IBM_GET_SYSTEM_PARAMETER);
54	struct rtas_work_area *work_area;
55	s32 fwrc;
56	int ret;
57
58	might_sleep();
59
60	if (WARN_ON(!buf))
61		return -EFAULT;
62
63	if (token == RTAS_UNKNOWN_SERVICE)
64		return -ENOENT;
65
66	work_area = rtas_work_area_alloc(sizeof(*buf));
67
68	memcpy(rtas_work_area_raw_buf(work_area), buf, sizeof(*buf));
69
70	do {
71		fwrc = rtas_call(token, 3, 1, NULL, param.token,
72				 rtas_work_area_phys(work_area),
73				 rtas_work_area_size(work_area));
74	} while (rtas_busy_delay(fwrc));
75
76	switch (fwrc) {
77	case 0:
78		ret = 0;
79		memcpy(buf, rtas_work_area_raw_buf(work_area), sizeof(*buf));
80		break;
81	case -3: /* parameter not implemented */
82		ret = -EOPNOTSUPP;
83		break;
84	case -9002: /* this partition not authorized to retrieve this parameter */
85		ret = -EPERM;
86		break;
87	case -9999: /* "parameter error" e.g. the buffer is too small */
88		ret = -EINVAL;
89		break;
90	default:
91		pr_err("unexpected ibm,get-system-parameter result %d\n", fwrc);
92		fallthrough;
93	case -1: /* Hardware/platform error */
94		ret = -EIO;
95		break;
96	}
97
98	rtas_work_area_free(work_area);
99
100	return ret;
101}
102
103int papr_sysparm_set(papr_sysparm_t param, const struct papr_sysparm_buf *buf)
104{
105	const s32 token = rtas_function_token(RTAS_FN_IBM_SET_SYSTEM_PARAMETER);
106	struct rtas_work_area *work_area;
107	s32 fwrc;
108	int ret;
109
110	might_sleep();
111
112	if (WARN_ON(!buf))
113		return -EFAULT;
114
115	if (token == RTAS_UNKNOWN_SERVICE)
116		return -ENOENT;
117
118	work_area = rtas_work_area_alloc(sizeof(*buf));
119
120	memcpy(rtas_work_area_raw_buf(work_area), buf, sizeof(*buf));
121
122	do {
123		fwrc = rtas_call(token, 2, 1, NULL, param.token,
124				 rtas_work_area_phys(work_area));
125	} while (rtas_busy_delay(fwrc));
126
127	switch (fwrc) {
128	case 0:
129		ret = 0;
130		break;
131	case -3: /* parameter not supported */
132		ret = -EOPNOTSUPP;
133		break;
134	case -9002: /* this partition not authorized to modify this parameter */
135		ret = -EPERM;
136		break;
137	case -9999: /* "parameter error" e.g. invalid input data */
138		ret = -EINVAL;
139		break;
140	default:
141		pr_err("unexpected ibm,set-system-parameter result %d\n", fwrc);
142		fallthrough;
143	case -1: /* Hardware/platform error */
144		ret = -EIO;
145		break;
146	}
147
148	rtas_work_area_free(work_area);
149
150	return ret;
151}
152