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
71 if (!pa_dev->vdata->cmdresp_reg || !pa_dev->vdata->cmdbuff_addr_lo_reg ||
72 !pa_dev->vdata->cmdbuff_addr_hi_reg)
73 return -ENODEV;
74
75 cmd = psp->io_regs + pa_dev->vdata->cmdresp_reg;
76 lo = psp->io_regs + pa_dev->vdata->cmdbuff_addr_lo_reg;
77 hi = psp->io_regs + pa_dev->vdata->cmdbuff_addr_hi_reg;
78
79 mutex_lock(&pa_dev->mailbox_mutex);
80
81 if (check_recovery(cmd)) {
82 dev_dbg(psp->dev, "platform mailbox is in recovery\n");
83 ret = -EBUSY;
84 goto unlock;
85 }
86
87 if (wait_cmd(cmd)) {
88 dev_dbg(psp->dev, "platform mailbox is not done processing command\n");
89 ret = -EBUSY;
90 goto unlock;
91 }
92
93 /*
94 * Fill mailbox with address of command-response buffer, which will be
95 * used for sending i2c requests as well as reading status returned by
96 * PSP. Use physical address of buffer, since PSP will map this region.
97 */
98 req_addr = __psp_pa(req);
99 iowrite32(lower_32_bits(req_addr), lo);
100 iowrite32(upper_32_bits(req_addr), hi);
101
102 print_hex_dump_debug("->psp ", DUMP_PREFIX_OFFSET, 16, 2, req,
103 req->header.payload_size, false);
104
105 /* Write command register to trigger processing */
106 cmd_reg = FIELD_PREP(PSP_CMDRESP_CMD, msg);
107 iowrite32(cmd_reg, cmd);
108
109 if (wait_cmd(cmd)) {
110 ret = -ETIMEDOUT;
111 goto unlock;
112 }
113
114 /* Ensure it was triggered by this driver */
115 if (ioread32(lo) != lower_32_bits(req_addr) ||
116 ioread32(hi) != upper_32_bits(req_addr)) {
117 ret = -EBUSY;
118 goto unlock;
119 }
120
121 /*
122 * Read status from PSP. If status is non-zero, it indicates an error
123 * occurred during "processing" of the command.
124 * If status is zero, it indicates the command was "processed"
125 * successfully, but the result of the command is in the payload.
126 * Return both cases to the caller as -EIO to investigate.
127 */
128 cmd_reg = ioread32(cmd);
129 if (FIELD_GET(PSP_CMDRESP_STS, cmd_reg))
130 req->header.status = FIELD_GET(PSP_CMDRESP_STS, cmd_reg);
131 if (req->header.status) {
132 ret = -EIO;
133 goto unlock;
134 }
135
136 print_hex_dump_debug("<-psp ", DUMP_PREFIX_OFFSET, 16, 2, req,
137 req->header.payload_size, false);
138
139 ret = 0;
140
141unlock:
142 mutex_unlock(lock: &pa_dev->mailbox_mutex);
143
144 return ret;
145}
146EXPORT_SYMBOL_GPL(psp_send_platform_access_msg);
147
148int psp_ring_platform_doorbell(int msg, u32 *result)
149{
150 struct psp_device *psp = psp_get_master_device();
151 struct psp_platform_access_device *pa_dev;
152 u32 __iomem *button, *cmd;
153 int ret, val;
154
155 if (!psp || !psp->platform_access_data)
156 return -ENODEV;
157
158 pa_dev = psp->platform_access_data;
159 button = psp->io_regs + pa_dev->vdata->doorbell_button_reg;
160 cmd = psp->io_regs + pa_dev->vdata->doorbell_cmd_reg;
161
162 mutex_lock(&pa_dev->doorbell_mutex);
163
164 if (wait_cmd(cmd)) {
165 dev_err(psp->dev, "doorbell command not done processing\n");
166 ret = -EBUSY;
167 goto unlock;
168 }
169
170 iowrite32(FIELD_PREP(DOORBELL_CMDRESP_STS, msg), cmd);
171 iowrite32(PSP_DRBL_RING, button);
172
173 if (wait_cmd(cmd)) {
174 ret = -ETIMEDOUT;
175 goto unlock;
176 }
177
178 val = FIELD_GET(DOORBELL_CMDRESP_STS, ioread32(cmd));
179 if (val) {
180 if (result)
181 *result = val;
182 ret = -EIO;
183 goto unlock;
184 }
185
186 ret = 0;
187unlock:
188 mutex_unlock(lock: &pa_dev->doorbell_mutex);
189
190 return ret;
191}
192EXPORT_SYMBOL_GPL(psp_ring_platform_doorbell);
193
194void platform_access_dev_destroy(struct psp_device *psp)
195{
196 struct psp_platform_access_device *pa_dev = psp->platform_access_data;
197
198 if (!pa_dev)
199 return;
200
201 mutex_destroy(lock: &pa_dev->mailbox_mutex);
202 mutex_destroy(lock: &pa_dev->doorbell_mutex);
203 psp->platform_access_data = NULL;
204}
205
206int platform_access_dev_init(struct psp_device *psp)
207{
208 struct device *dev = psp->dev;
209 struct psp_platform_access_device *pa_dev;
210
211 pa_dev = devm_kzalloc(dev, size: sizeof(*pa_dev), GFP_KERNEL);
212 if (!pa_dev)
213 return -ENOMEM;
214
215 psp->platform_access_data = pa_dev;
216 pa_dev->psp = psp;
217 pa_dev->dev = dev;
218
219 pa_dev->vdata = (struct platform_access_vdata *)psp->vdata->platform_access;
220
221 mutex_init(&pa_dev->mailbox_mutex);
222 mutex_init(&pa_dev->doorbell_mutex);
223
224 dev_dbg(dev, "platform access enabled\n");
225
226 return 0;
227}
228

source code of linux/drivers/crypto/ccp/platform-access.c