1// SPDX-License-Identifier: GPL-2.0
2/*
3 * System Control and Management Interface (SCMI) Message SMC/HVC
4 * Transport driver
5 *
6 * Copyright 2020 NXP
7 */
8
9#include <linux/arm-smccc.h>
10#include <linux/atomic.h>
11#include <linux/device.h>
12#include <linux/err.h>
13#include <linux/interrupt.h>
14#include <linux/mutex.h>
15#include <linux/of.h>
16#include <linux/of_address.h>
17#include <linux/of_irq.h>
18#include <linux/limits.h>
19#include <linux/processor.h>
20#include <linux/slab.h>
21
22#include "common.h"
23
24/*
25 * The shmem address is split into 4K page and offset.
26 * This is to make sure the parameters fit in 32bit arguments of the
27 * smc/hvc call to keep it uniform across smc32/smc64 conventions.
28 * This however limits the shmem address to 44 bit.
29 *
30 * These optional parameters can be used to distinguish among multiple
31 * scmi instances that are using the same smc-id.
32 * The page parameter is passed in r1/x1/w1 register and the offset parameter
33 * is passed in r2/x2/w2 register.
34 */
35
36#define SHMEM_SIZE (SZ_4K)
37#define SHMEM_SHIFT 12
38#define SHMEM_PAGE(x) (_UL((x) >> SHMEM_SHIFT))
39#define SHMEM_OFFSET(x) ((x) & (SHMEM_SIZE - 1))
40
41/**
42 * struct scmi_smc - Structure representing a SCMI smc transport
43 *
44 * @irq: An optional IRQ for completion
45 * @cinfo: SCMI channel info
46 * @shmem: Transmit/Receive shared memory area
47 * @shmem_lock: Lock to protect access to Tx/Rx shared memory area.
48 * Used when NOT operating in atomic mode.
49 * @inflight: Atomic flag to protect access to Tx/Rx shared memory area.
50 * Used when operating in atomic mode.
51 * @func_id: smc/hvc call function id
52 * @param_page: 4K page number of the shmem channel
53 * @param_offset: Offset within the 4K page of the shmem channel
54 * @cap_id: smc/hvc doorbell's capability id to be used on Qualcomm virtual
55 * platforms
56 */
57
58struct scmi_smc {
59 int irq;
60 struct scmi_chan_info *cinfo;
61 struct scmi_shared_mem __iomem *shmem;
62 /* Protect access to shmem area */
63 struct mutex shmem_lock;
64#define INFLIGHT_NONE MSG_TOKEN_MAX
65 atomic_t inflight;
66 unsigned long func_id;
67 unsigned long param_page;
68 unsigned long param_offset;
69 unsigned long cap_id;
70};
71
72static irqreturn_t smc_msg_done_isr(int irq, void *data)
73{
74 struct scmi_smc *scmi_info = data;
75
76 scmi_rx_callback(cinfo: scmi_info->cinfo,
77 msg_hdr: shmem_read_header(shmem: scmi_info->shmem), NULL);
78
79 return IRQ_HANDLED;
80}
81
82static bool smc_chan_available(struct device_node *of_node, int idx)
83{
84 struct device_node *np = of_parse_phandle(np: of_node, phandle_name: "shmem", index: 0);
85 if (!np)
86 return false;
87
88 of_node_put(node: np);
89 return true;
90}
91
92static inline void smc_channel_lock_init(struct scmi_smc *scmi_info)
93{
94 if (IS_ENABLED(CONFIG_ARM_SCMI_TRANSPORT_SMC_ATOMIC_ENABLE))
95 atomic_set(v: &scmi_info->inflight, INFLIGHT_NONE);
96 else
97 mutex_init(&scmi_info->shmem_lock);
98}
99
100static bool smc_xfer_inflight(struct scmi_xfer *xfer, atomic_t *inflight)
101{
102 int ret;
103
104 ret = atomic_cmpxchg(v: inflight, INFLIGHT_NONE, new: xfer->hdr.seq);
105
106 return ret == INFLIGHT_NONE;
107}
108
109static inline void
110smc_channel_lock_acquire(struct scmi_smc *scmi_info,
111 struct scmi_xfer *xfer __maybe_unused)
112{
113 if (IS_ENABLED(CONFIG_ARM_SCMI_TRANSPORT_SMC_ATOMIC_ENABLE))
114 spin_until_cond(smc_xfer_inflight(xfer, &scmi_info->inflight));
115 else
116 mutex_lock(&scmi_info->shmem_lock);
117}
118
119static inline void smc_channel_lock_release(struct scmi_smc *scmi_info)
120{
121 if (IS_ENABLED(CONFIG_ARM_SCMI_TRANSPORT_SMC_ATOMIC_ENABLE))
122 atomic_set(v: &scmi_info->inflight, INFLIGHT_NONE);
123 else
124 mutex_unlock(lock: &scmi_info->shmem_lock);
125}
126
127static int smc_chan_setup(struct scmi_chan_info *cinfo, struct device *dev,
128 bool tx)
129{
130 struct device *cdev = cinfo->dev;
131 unsigned long cap_id = ULONG_MAX;
132 struct scmi_smc *scmi_info;
133 resource_size_t size;
134 struct resource res;
135 struct device_node *np;
136 u32 func_id;
137 int ret;
138
139 if (!tx)
140 return -ENODEV;
141
142 scmi_info = devm_kzalloc(dev, size: sizeof(*scmi_info), GFP_KERNEL);
143 if (!scmi_info)
144 return -ENOMEM;
145
146 np = of_parse_phandle(np: cdev->of_node, phandle_name: "shmem", index: 0);
147 if (!of_device_is_compatible(device: np, "arm,scmi-shmem")) {
148 of_node_put(node: np);
149 return -ENXIO;
150 }
151
152 ret = of_address_to_resource(dev: np, index: 0, r: &res);
153 of_node_put(node: np);
154 if (ret) {
155 dev_err(cdev, "failed to get SCMI Tx shared memory\n");
156 return ret;
157 }
158
159 size = resource_size(res: &res);
160 scmi_info->shmem = devm_ioremap(dev, offset: res.start, size);
161 if (!scmi_info->shmem) {
162 dev_err(dev, "failed to ioremap SCMI Tx shared memory\n");
163 return -EADDRNOTAVAIL;
164 }
165
166 ret = of_property_read_u32(np: dev->of_node, propname: "arm,smc-id", out_value: &func_id);
167 if (ret < 0)
168 return ret;
169
170 if (of_device_is_compatible(device: dev->of_node, "qcom,scmi-smc")) {
171 void __iomem *ptr = (void __iomem *)scmi_info->shmem + size - 8;
172 /* The capability-id is kept in last 8 bytes of shmem.
173 * +-------+ <-- 0
174 * | shmem |
175 * +-------+ <-- size - 8
176 * | capId |
177 * +-------+ <-- size
178 */
179 memcpy_fromio(&cap_id, ptr, sizeof(cap_id));
180 }
181
182 if (of_device_is_compatible(device: dev->of_node, "arm,scmi-smc-param")) {
183 scmi_info->param_page = SHMEM_PAGE(res.start);
184 scmi_info->param_offset = SHMEM_OFFSET(res.start);
185 }
186 /*
187 * If there is an interrupt named "a2p", then the service and
188 * completion of a message is signaled by an interrupt rather than by
189 * the return of the SMC call.
190 */
191 scmi_info->irq = of_irq_get_byname(dev: cdev->of_node, name: "a2p");
192 if (scmi_info->irq > 0) {
193 ret = request_irq(irq: scmi_info->irq, handler: smc_msg_done_isr,
194 IRQF_NO_SUSPEND, name: dev_name(dev), dev: scmi_info);
195 if (ret) {
196 dev_err(dev, "failed to setup SCMI smc irq\n");
197 return ret;
198 }
199 } else {
200 cinfo->no_completion_irq = true;
201 }
202
203 scmi_info->func_id = func_id;
204 scmi_info->cap_id = cap_id;
205 scmi_info->cinfo = cinfo;
206 smc_channel_lock_init(scmi_info);
207 cinfo->transport_info = scmi_info;
208
209 return 0;
210}
211
212static int smc_chan_free(int id, void *p, void *data)
213{
214 struct scmi_chan_info *cinfo = p;
215 struct scmi_smc *scmi_info = cinfo->transport_info;
216
217 /*
218 * Different protocols might share the same chan info, so a previous
219 * smc_chan_free call might have already freed the structure.
220 */
221 if (!scmi_info)
222 return 0;
223
224 /* Ignore any possible further reception on the IRQ path */
225 if (scmi_info->irq > 0)
226 free_irq(scmi_info->irq, scmi_info);
227
228 cinfo->transport_info = NULL;
229 scmi_info->cinfo = NULL;
230
231 return 0;
232}
233
234static int smc_send_message(struct scmi_chan_info *cinfo,
235 struct scmi_xfer *xfer)
236{
237 struct scmi_smc *scmi_info = cinfo->transport_info;
238 struct arm_smccc_res res;
239
240 /*
241 * Channel will be released only once response has been
242 * surely fully retrieved, so after .mark_txdone()
243 */
244 smc_channel_lock_acquire(scmi_info, xfer);
245
246 shmem_tx_prepare(shmem: scmi_info->shmem, xfer, cinfo);
247
248 if (scmi_info->cap_id != ULONG_MAX)
249 arm_smccc_1_1_invoke(scmi_info->func_id, scmi_info->cap_id, 0,
250 0, 0, 0, 0, 0, &res);
251 else
252 arm_smccc_1_1_invoke(scmi_info->func_id, scmi_info->param_page,
253 scmi_info->param_offset, 0, 0, 0, 0, 0,
254 &res);
255
256 /* Only SMCCC_RET_NOT_SUPPORTED is valid error code */
257 if (res.a0) {
258 smc_channel_lock_release(scmi_info);
259 return -EOPNOTSUPP;
260 }
261
262 return 0;
263}
264
265static void smc_fetch_response(struct scmi_chan_info *cinfo,
266 struct scmi_xfer *xfer)
267{
268 struct scmi_smc *scmi_info = cinfo->transport_info;
269
270 shmem_fetch_response(shmem: scmi_info->shmem, xfer);
271}
272
273static void smc_mark_txdone(struct scmi_chan_info *cinfo, int ret,
274 struct scmi_xfer *__unused)
275{
276 struct scmi_smc *scmi_info = cinfo->transport_info;
277
278 smc_channel_lock_release(scmi_info);
279}
280
281static const struct scmi_transport_ops scmi_smc_ops = {
282 .chan_available = smc_chan_available,
283 .chan_setup = smc_chan_setup,
284 .chan_free = smc_chan_free,
285 .send_message = smc_send_message,
286 .mark_txdone = smc_mark_txdone,
287 .fetch_response = smc_fetch_response,
288};
289
290const struct scmi_desc scmi_smc_desc = {
291 .ops = &scmi_smc_ops,
292 .max_rx_timeout_ms = 30,
293 .max_msg = 20,
294 .max_msg_size = 128,
295 /*
296 * Setting .sync_cmds_atomic_replies to true for SMC assumes that,
297 * once the SMC instruction has completed successfully, the issued
298 * SCMI command would have been already fully processed by the SCMI
299 * platform firmware and so any possible response value expected
300 * for the issued command will be immmediately ready to be fetched
301 * from the shared memory area.
302 */
303 .sync_cmds_completed_on_ret = true,
304 .atomic_enabled = IS_ENABLED(CONFIG_ARM_SCMI_TRANSPORT_SMC_ATOMIC_ENABLE),
305};
306

source code of linux/drivers/firmware/arm_scmi/smc.c