tjh.dev
Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
kernel
os
linux
1// SPDX-License-Identifier: GPL-2.0
2/*
3 * AMD Platform Security Processor (PSP) Platform Access interface
4 *
5 * Copyright (C) 2023 Advanced Micro Devices, Inc.
6 *
7 * Author: Mario Limonciello <mario.limonciello@amd.com>
8 *
9 * Some of this code is adapted from drivers/i2c/busses/i2c-designware-amdpsp.c
10 * developed by Jan Dabros <jsd@semihalf.com> and Copyright (C) 2022 Google Inc.
11 *
12 */
13
14#include <linux/bitfield.h>
15#include <linux/errno.h>
16#include <linux/iopoll.h>
17#include <linux/mutex.h>
18
19#include "platform-access.h"
20
21#define PSP_CMD_TIMEOUT_US (500 * USEC_PER_MSEC)
22#define DOORBELL_CMDRESP_STS GENMASK(7, 0)
23
24/* Recovery field should be equal 0 to start sending commands */
25static int check_recovery(u32 __iomem *cmd)
26{
27 return FIELD_GET(PSP_CMDRESP_RECOVERY, ioread32(cmd));
28}
29
30static int wait_cmd(u32 __iomem *cmd)
31{
32 u32 tmp, expected;
33
34 /* Expect mbox_cmd to be cleared and ready bit to be set by PSP */
35 expected = FIELD_PREP(PSP_CMDRESP_RESP, 1);
36
37 /*
38 * Check for readiness of PSP mailbox in a tight loop in order to
39 * process further as soon as command was consumed.
40 */
41 return readl_poll_timeout(cmd, tmp, (tmp & expected), 0,
42 PSP_CMD_TIMEOUT_US);
43}
44
45int psp_check_platform_access_status(void)
46{
47 struct psp_device *psp = psp_get_master_device();
48
49 if (!psp || !psp->platform_access_data)
50 return -ENODEV;
51
52 return 0;
53}
54EXPORT_SYMBOL(psp_check_platform_access_status);
55
56int psp_send_platform_access_msg(enum psp_platform_access_msg msg,
57 struct psp_request *req)
58{
59 struct psp_device *psp = psp_get_master_device();
60 u32 __iomem *cmd, *lo, *hi;
61 struct psp_platform_access_device *pa_dev;
62 phys_addr_t req_addr;
63 u32 cmd_reg;
64 int ret;
65
66 if (!psp || !psp->platform_access_data)
67 return -ENODEV;
68
69 pa_dev = psp->platform_access_data;
70 cmd = psp->io_regs + pa_dev->vdata->cmdresp_reg;
71 lo = psp->io_regs + pa_dev->vdata->cmdbuff_addr_lo_reg;
72 hi = psp->io_regs + pa_dev->vdata->cmdbuff_addr_hi_reg;
73
74 mutex_lock(&pa_dev->mailbox_mutex);
75
76 if (check_recovery(cmd)) {
77 dev_dbg(psp->dev, "platform mailbox is in recovery\n");
78 ret = -EBUSY;
79 goto unlock;
80 }
81
82 if (wait_cmd(cmd)) {
83 dev_dbg(psp->dev, "platform mailbox is not done processing command\n");
84 ret = -EBUSY;
85 goto unlock;
86 }
87
88 /*
89 * Fill mailbox with address of command-response buffer, which will be
90 * used for sending i2c requests as well as reading status returned by
91 * PSP. Use physical address of buffer, since PSP will map this region.
92 */
93 req_addr = __psp_pa(req);
94 iowrite32(lower_32_bits(req_addr), lo);
95 iowrite32(upper_32_bits(req_addr), hi);
96
97 print_hex_dump_debug("->psp ", DUMP_PREFIX_OFFSET, 16, 2, req,
98 req->header.payload_size, false);
99
100 /* Write command register to trigger processing */
101 cmd_reg = FIELD_PREP(PSP_CMDRESP_CMD, msg);
102 iowrite32(cmd_reg, cmd);
103
104 if (wait_cmd(cmd)) {
105 ret = -ETIMEDOUT;
106 goto unlock;
107 }
108
109 /* Ensure it was triggered by this driver */
110 if (ioread32(lo) != lower_32_bits(req_addr) ||
111 ioread32(hi) != upper_32_bits(req_addr)) {
112 ret = -EBUSY;
113 goto unlock;
114 }
115
116 /* Store the status in request header for caller to investigate */
117 cmd_reg = ioread32(cmd);
118 req->header.status = FIELD_GET(PSP_CMDRESP_STS, cmd_reg);
119 if (req->header.status) {
120 ret = -EIO;
121 goto unlock;
122 }
123
124 print_hex_dump_debug("<-psp ", DUMP_PREFIX_OFFSET, 16, 2, req,
125 req->header.payload_size, false);
126
127 ret = 0;
128
129unlock:
130 mutex_unlock(&pa_dev->mailbox_mutex);
131
132 return ret;
133}
134EXPORT_SYMBOL_GPL(psp_send_platform_access_msg);
135
136int psp_ring_platform_doorbell(int msg, u32 *result)
137{
138 struct psp_device *psp = psp_get_master_device();
139 struct psp_platform_access_device *pa_dev;
140 u32 __iomem *button, *cmd;
141 int ret, val;
142
143 if (!psp || !psp->platform_access_data)
144 return -ENODEV;
145
146 pa_dev = psp->platform_access_data;
147 button = psp->io_regs + pa_dev->vdata->doorbell_button_reg;
148 cmd = psp->io_regs + pa_dev->vdata->doorbell_cmd_reg;
149
150 mutex_lock(&pa_dev->doorbell_mutex);
151
152 if (wait_cmd(cmd)) {
153 dev_err(psp->dev, "doorbell command not done processing\n");
154 ret = -EBUSY;
155 goto unlock;
156 }
157
158 iowrite32(FIELD_PREP(DOORBELL_CMDRESP_STS, msg), cmd);
159 iowrite32(PSP_DRBL_RING, button);
160
161 if (wait_cmd(cmd)) {
162 ret = -ETIMEDOUT;
163 goto unlock;
164 }
165
166 val = FIELD_GET(DOORBELL_CMDRESP_STS, ioread32(cmd));
167 if (val) {
168 if (result)
169 *result = val;
170 ret = -EIO;
171 goto unlock;
172 }
173
174 ret = 0;
175unlock:
176 mutex_unlock(&pa_dev->doorbell_mutex);
177
178 return ret;
179}
180EXPORT_SYMBOL_GPL(psp_ring_platform_doorbell);
181
182void platform_access_dev_destroy(struct psp_device *psp)
183{
184 struct psp_platform_access_device *pa_dev = psp->platform_access_data;
185
186 if (!pa_dev)
187 return;
188
189 mutex_destroy(&pa_dev->mailbox_mutex);
190 mutex_destroy(&pa_dev->doorbell_mutex);
191 psp->platform_access_data = NULL;
192}
193
194int platform_access_dev_init(struct psp_device *psp)
195{
196 struct device *dev = psp->dev;
197 struct psp_platform_access_device *pa_dev;
198
199 pa_dev = devm_kzalloc(dev, sizeof(*pa_dev), GFP_KERNEL);
200 if (!pa_dev)
201 return -ENOMEM;
202
203 psp->platform_access_data = pa_dev;
204 pa_dev->psp = psp;
205 pa_dev->dev = dev;
206
207 pa_dev->vdata = (struct platform_access_vdata *)psp->vdata->platform_access;
208
209 mutex_init(&pa_dev->mailbox_mutex);
210 mutex_init(&pa_dev->doorbell_mutex);
211
212 dev_dbg(dev, "platform access enabled\n");
213
214 return 0;
215}