1 // SPDX-License-Identifier: GPL-2.0
5 #include <linux/psp-platform-access.h>
7 #include <linux/workqueue.h>
9 #include "i2c-designware-core.h"
11 #define PSP_I2C_RESERVATION_TIME_MS 100
13 #define PSP_I2C_REQ_RETRY_CNT 400
14 #define PSP_I2C_REQ_RETRY_DELAY_US (25 * USEC_PER_MSEC)
15 #define PSP_I2C_REQ_STS_OK 0x0
16 #define PSP_I2C_REQ_STS_BUS_BUSY 0x1
17 #define PSP_I2C_REQ_STS_INV_PARAM 0x3
19 enum psp_i2c_req_type
{
26 struct psp_req_buffer_hdr hdr
;
27 enum psp_i2c_req_type type
;
30 static DEFINE_MUTEX(psp_i2c_access_mutex
);
31 static unsigned long psp_i2c_sem_acquired
;
32 static u32 psp_i2c_access_count
;
33 static bool psp_i2c_mbox_fail
;
34 static struct device
*psp_i2c_dev
;
36 static int (*_psp_send_i2c_req
)(struct psp_i2c_req
*req
);
38 /* Helper to verify status returned by PSP */
39 static int check_i2c_req_sts(struct psp_i2c_req
*req
)
43 /* Status field in command-response buffer is updated by PSP */
44 status
= READ_ONCE(req
->hdr
.status
);
47 case PSP_I2C_REQ_STS_OK
:
49 case PSP_I2C_REQ_STS_BUS_BUSY
:
51 case PSP_I2C_REQ_STS_INV_PARAM
:
58 * Errors in x86-PSP i2c-arbitration protocol may occur at two levels:
59 * 1. mailbox communication - PSP is not operational or some IO errors with
60 * basic communication had happened.
61 * 2. i2c-requests - PSP refuses to grant i2c arbitration to x86 for too long.
63 * In order to distinguish between these in error handling code all mailbox
64 * communication errors on the first level (from CCP symbols) will be passed
65 * up and if -EIO is returned the second level will be checked.
67 static int psp_send_i2c_req_cezanne(struct psp_i2c_req
*req
)
71 ret
= psp_send_platform_access_msg(PSP_I2C_REQ_BUS_CMD
, (struct psp_request
*)req
);
73 return check_i2c_req_sts(req
);
78 static int psp_send_i2c_req_doorbell(struct psp_i2c_req
*req
)
82 ret
= psp_ring_platform_doorbell(req
->type
, &req
->hdr
.status
);
84 return check_i2c_req_sts(req
);
89 static int psp_send_i2c_req(enum psp_i2c_req_type i2c_req_type
)
91 struct psp_i2c_req
*req
;
95 /* Allocate command-response buffer */
96 req
= kzalloc(sizeof(*req
), GFP_KERNEL
);
100 req
->hdr
.payload_size
= sizeof(*req
);
101 req
->type
= i2c_req_type
;
104 ret
= read_poll_timeout(_psp_send_i2c_req
, status
,
106 PSP_I2C_REQ_RETRY_DELAY_US
,
107 PSP_I2C_REQ_RETRY_CNT
* PSP_I2C_REQ_RETRY_DELAY_US
,
110 dev_err(psp_i2c_dev
, "Timed out waiting for PSP to %s I2C bus\n",
111 (i2c_req_type
== PSP_I2C_REQ_ACQUIRE
) ?
112 "release" : "acquire");
118 dev_err(psp_i2c_dev
, "PSP communication error\n");
122 dev_dbg(psp_i2c_dev
, "Request accepted by PSP after %ums\n",
123 jiffies_to_msecs(jiffies
- start
));
127 dev_err(psp_i2c_dev
, "Assume i2c bus is for exclusive host usage\n");
128 psp_i2c_mbox_fail
= true;
135 static void release_bus(void)
139 if (!psp_i2c_sem_acquired
)
142 status
= psp_send_i2c_req(PSP_I2C_REQ_RELEASE
);
146 dev_dbg(psp_i2c_dev
, "PSP semaphore held for %ums\n",
147 jiffies_to_msecs(jiffies
- psp_i2c_sem_acquired
));
149 psp_i2c_sem_acquired
= 0;
152 static void psp_release_i2c_bus_deferred(struct work_struct
*work
)
154 mutex_lock(&psp_i2c_access_mutex
);
157 * If there is any pending transaction, cannot release the bus here.
158 * psp_release_i2c_bus() will take care of this later.
160 if (psp_i2c_access_count
)
166 mutex_unlock(&psp_i2c_access_mutex
);
168 static DECLARE_DELAYED_WORK(release_queue
, psp_release_i2c_bus_deferred
);
170 static int psp_acquire_i2c_bus(void)
174 mutex_lock(&psp_i2c_access_mutex
);
176 /* Return early if mailbox malfunctioned */
177 if (psp_i2c_mbox_fail
)
180 psp_i2c_access_count
++;
183 * No need to request bus arbitration once we are inside semaphore
184 * reservation period.
186 if (psp_i2c_sem_acquired
)
189 status
= psp_send_i2c_req(PSP_I2C_REQ_ACQUIRE
);
193 psp_i2c_sem_acquired
= jiffies
;
195 schedule_delayed_work(&release_queue
,
196 msecs_to_jiffies(PSP_I2C_RESERVATION_TIME_MS
));
199 * In case of errors with PSP arbitrator psp_i2c_mbox_fail variable is
200 * set above. As a consequence consecutive calls to acquire will bypass
201 * communication with PSP. At any case i2c bus is granted to the caller,
202 * thus always return success.
205 mutex_unlock(&psp_i2c_access_mutex
);
209 static void psp_release_i2c_bus(void)
211 mutex_lock(&psp_i2c_access_mutex
);
213 /* Return early if mailbox was malfunctioned */
214 if (psp_i2c_mbox_fail
)
218 * If we are last owner of PSP semaphore, need to release arbitration
221 psp_i2c_access_count
--;
222 if (psp_i2c_access_count
)
226 * Send a release command to PSP if the semaphore reservation timeout
227 * elapsed but x86 still owns the controller.
229 if (!delayed_work_pending(&release_queue
))
233 mutex_unlock(&psp_i2c_access_mutex
);
237 * Locking methods are based on the default implementation from
238 * drivers/i2c/i2c-core-base.c, but with PSP acquire and release operations
239 * added. With this in place we can ensure that i2c clients on the bus shared
240 * with PSP are able to lock HW access to the bus for arbitrary number of
241 * operations - that is e.g. write-wait-read.
243 static void i2c_adapter_dw_psp_lock_bus(struct i2c_adapter
*adapter
,
246 psp_acquire_i2c_bus();
247 rt_mutex_lock_nested(&adapter
->bus_lock
, i2c_adapter_depth(adapter
));
250 static int i2c_adapter_dw_psp_trylock_bus(struct i2c_adapter
*adapter
,
255 ret
= rt_mutex_trylock(&adapter
->bus_lock
);
259 psp_acquire_i2c_bus();
264 static void i2c_adapter_dw_psp_unlock_bus(struct i2c_adapter
*adapter
,
267 psp_release_i2c_bus();
268 rt_mutex_unlock(&adapter
->bus_lock
);
271 static const struct i2c_lock_operations i2c_dw_psp_lock_ops
= {
272 .lock_bus
= i2c_adapter_dw_psp_lock_bus
,
273 .trylock_bus
= i2c_adapter_dw_psp_trylock_bus
,
274 .unlock_bus
= i2c_adapter_dw_psp_unlock_bus
,
277 int i2c_dw_amdpsp_probe_lock_support(struct dw_i2c_dev
*dev
)
279 struct pci_dev
*rdev
;
281 if (!IS_REACHABLE(CONFIG_CRYPTO_DEV_CCP_DD
))
287 if (!(dev
->flags
& ARBITRATION_SEMAPHORE
))
290 /* Allow to bind only one instance of a driver */
294 /* Cezanne uses platform mailbox, Mendocino and later use doorbell */
295 rdev
= pci_get_domain_bus_and_slot(0, 0, PCI_DEVFN(0, 0));
296 if (rdev
->device
== 0x1630)
297 _psp_send_i2c_req
= psp_send_i2c_req_cezanne
;
299 _psp_send_i2c_req
= psp_send_i2c_req_doorbell
;
302 if (psp_check_platform_access_status())
303 return -EPROBE_DEFER
;
305 psp_i2c_dev
= dev
->dev
;
307 dev_info(psp_i2c_dev
, "I2C bus managed by AMD PSP\n");
310 * Install global locking callbacks for adapter as well as internal i2c
313 dev
->adapter
.lock_ops
= &i2c_dw_psp_lock_ops
;
314 dev
->acquire_lock
= psp_acquire_i2c_bus
;
315 dev
->release_lock
= psp_release_i2c_bus
;