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/platform_device.h>
20 #include <linux/processor.h>
21 #include <linux/slab.h>
22
23 #include "../common.h"
24
25 /*
26 * The shmem address is split into 4K page and offset.
27 * This is to make sure the parameters fit in 32bit arguments of the
28 * smc/hvc call to keep it uniform across smc32/smc64 conventions.
29 * This however limits the shmem address to 44 bit.
30 *
31 * These optional parameters can be used to distinguish among multiple
32 * scmi instances that are using the same smc-id.
33 * The page parameter is passed in r1/x1/w1 register and the offset parameter
34 * is passed in r2/x2/w2 register.
35 */
36
37 #define SHMEM_SIZE (SZ_4K)
38 #define SHMEM_SHIFT 12
39 #define SHMEM_PAGE(x) (_UL((x) >> SHMEM_SHIFT))
40 #define SHMEM_OFFSET(x) ((x) & (SHMEM_SIZE - 1))
41
42 /**
43 * struct scmi_smc - Structure representing a SCMI smc transport
44 *
45 * @irq: An optional IRQ for completion
46 * @cinfo: SCMI channel info
47 * @shmem: Transmit/Receive shared memory area
48 * @shmem_lock: Lock to protect access to Tx/Rx shared memory area.
49 * Used when NOT operating in atomic mode.
50 * @inflight: Atomic flag to protect access to Tx/Rx shared memory area.
51 * Used when operating in atomic mode.
52 * @func_id: smc/hvc call function id
53 * @param_page: 4K page number of the shmem channel
54 * @param_offset: Offset within the 4K page of the shmem channel
55 * @cap_id: smc/hvc doorbell's capability id to be used on Qualcomm virtual
56 * platforms
57 */
58
59 struct scmi_smc {
60 int irq;
61 struct scmi_chan_info *cinfo;
62 struct scmi_shared_mem __iomem *shmem;
63 /* Protect access to shmem area */
64 struct mutex shmem_lock;
65 #define INFLIGHT_NONE MSG_TOKEN_MAX
66 atomic_t inflight;
67 unsigned long func_id;
68 unsigned long param_page;
69 unsigned long param_offset;
70 unsigned long cap_id;
71 };
72
73 static struct scmi_transport_core_operations *core;
74
smc_msg_done_isr(int irq,void * data)75 static irqreturn_t smc_msg_done_isr(int irq, void *data)
76 {
77 struct scmi_smc *scmi_info = data;
78
79 core->rx_callback(scmi_info->cinfo,
80 core->shmem->read_header(scmi_info->shmem), NULL);
81
82 return IRQ_HANDLED;
83 }
84
smc_chan_available(struct device_node * of_node,int idx)85 static bool smc_chan_available(struct device_node *of_node, int idx)
86 {
87 struct device_node *np __free(device_node) =
88 of_parse_phandle(of_node, "shmem", 0);
89 if (!np)
90 return false;
91
92 return true;
93 }
94
smc_channel_lock_init(struct scmi_smc * scmi_info)95 static inline void smc_channel_lock_init(struct scmi_smc *scmi_info)
96 {
97 if (IS_ENABLED(CONFIG_ARM_SCMI_TRANSPORT_SMC_ATOMIC_ENABLE))
98 atomic_set(&scmi_info->inflight, INFLIGHT_NONE);
99 else
100 mutex_init(&scmi_info->shmem_lock);
101 }
102
smc_xfer_inflight(struct scmi_xfer * xfer,atomic_t * inflight)103 static bool smc_xfer_inflight(struct scmi_xfer *xfer, atomic_t *inflight)
104 {
105 int ret;
106
107 ret = atomic_cmpxchg(inflight, INFLIGHT_NONE, xfer->hdr.seq);
108
109 return ret == INFLIGHT_NONE;
110 }
111
112 static inline void
smc_channel_lock_acquire(struct scmi_smc * scmi_info,struct scmi_xfer * xfer __maybe_unused)113 smc_channel_lock_acquire(struct scmi_smc *scmi_info,
114 struct scmi_xfer *xfer __maybe_unused)
115 {
116 if (IS_ENABLED(CONFIG_ARM_SCMI_TRANSPORT_SMC_ATOMIC_ENABLE))
117 spin_until_cond(smc_xfer_inflight(xfer, &scmi_info->inflight));
118 else
119 mutex_lock(&scmi_info->shmem_lock);
120 }
121
smc_channel_lock_release(struct scmi_smc * scmi_info)122 static inline void smc_channel_lock_release(struct scmi_smc *scmi_info)
123 {
124 if (IS_ENABLED(CONFIG_ARM_SCMI_TRANSPORT_SMC_ATOMIC_ENABLE))
125 atomic_set(&scmi_info->inflight, INFLIGHT_NONE);
126 else
127 mutex_unlock(&scmi_info->shmem_lock);
128 }
129
smc_chan_setup(struct scmi_chan_info * cinfo,struct device * dev,bool tx)130 static int smc_chan_setup(struct scmi_chan_info *cinfo, struct device *dev,
131 bool tx)
132 {
133 struct device *cdev = cinfo->dev;
134 unsigned long cap_id = ULONG_MAX;
135 struct scmi_smc *scmi_info;
136 struct resource res = {};
137 u32 func_id;
138 int ret;
139
140 if (!tx)
141 return -ENODEV;
142
143 scmi_info = devm_kzalloc(dev, sizeof(*scmi_info), GFP_KERNEL);
144 if (!scmi_info)
145 return -ENOMEM;
146
147 scmi_info->shmem = core->shmem->setup_iomap(cinfo, dev, tx, &res);
148 if (IS_ERR(scmi_info->shmem))
149 return PTR_ERR(scmi_info->shmem);
150
151 ret = of_property_read_u32(dev->of_node, "arm,smc-id", &func_id);
152 if (ret < 0)
153 return ret;
154
155 if (of_device_is_compatible(dev->of_node, "qcom,scmi-smc")) {
156 resource_size_t size = resource_size(&res);
157 void __iomem *ptr = (void __iomem *)scmi_info->shmem + size - 8;
158 /* The capability-id is kept in last 8 bytes of shmem.
159 * +-------+ <-- 0
160 * | shmem |
161 * +-------+ <-- size - 8
162 * | capId |
163 * +-------+ <-- size
164 */
165 memcpy_fromio(&cap_id, ptr, sizeof(cap_id));
166 }
167
168 if (of_device_is_compatible(dev->of_node, "arm,scmi-smc-param")) {
169 scmi_info->param_page = SHMEM_PAGE(res.start);
170 scmi_info->param_offset = SHMEM_OFFSET(res.start);
171 }
172 /*
173 * If there is an interrupt named "a2p", then the service and
174 * completion of a message is signaled by an interrupt rather than by
175 * the return of the SMC call.
176 */
177 scmi_info->irq = of_irq_get_byname(cdev->of_node, "a2p");
178 if (scmi_info->irq > 0) {
179 ret = request_irq(scmi_info->irq, smc_msg_done_isr,
180 IRQF_NO_SUSPEND, dev_name(dev), scmi_info);
181 if (ret) {
182 dev_err(dev, "failed to setup SCMI smc irq\n");
183 return ret;
184 }
185 } else {
186 cinfo->no_completion_irq = true;
187 }
188
189 scmi_info->func_id = func_id;
190 scmi_info->cap_id = cap_id;
191 scmi_info->cinfo = cinfo;
192 smc_channel_lock_init(scmi_info);
193 cinfo->transport_info = scmi_info;
194
195 return 0;
196 }
197
smc_chan_free(int id,void * p,void * data)198 static int smc_chan_free(int id, void *p, void *data)
199 {
200 struct scmi_chan_info *cinfo = p;
201 struct scmi_smc *scmi_info = cinfo->transport_info;
202
203 /*
204 * Different protocols might share the same chan info, so a previous
205 * smc_chan_free call might have already freed the structure.
206 */
207 if (!scmi_info)
208 return 0;
209
210 /* Ignore any possible further reception on the IRQ path */
211 if (scmi_info->irq > 0)
212 free_irq(scmi_info->irq, scmi_info);
213
214 cinfo->transport_info = NULL;
215 scmi_info->cinfo = NULL;
216
217 return 0;
218 }
219
smc_send_message(struct scmi_chan_info * cinfo,struct scmi_xfer * xfer)220 static int smc_send_message(struct scmi_chan_info *cinfo,
221 struct scmi_xfer *xfer)
222 {
223 struct scmi_smc *scmi_info = cinfo->transport_info;
224 struct arm_smccc_res res;
225
226 /*
227 * Channel will be released only once response has been
228 * surely fully retrieved, so after .mark_txdone()
229 */
230 smc_channel_lock_acquire(scmi_info, xfer);
231
232 core->shmem->tx_prepare(scmi_info->shmem, xfer, cinfo);
233
234 if (scmi_info->cap_id != ULONG_MAX)
235 arm_smccc_1_1_invoke(scmi_info->func_id, scmi_info->cap_id, 0,
236 0, 0, 0, 0, 0, &res);
237 else
238 arm_smccc_1_1_invoke(scmi_info->func_id, scmi_info->param_page,
239 scmi_info->param_offset, 0, 0, 0, 0, 0,
240 &res);
241
242 /* Only SMCCC_RET_NOT_SUPPORTED is valid error code */
243 if (res.a0) {
244 smc_channel_lock_release(scmi_info);
245 return -EOPNOTSUPP;
246 }
247
248 return 0;
249 }
250
smc_fetch_response(struct scmi_chan_info * cinfo,struct scmi_xfer * xfer)251 static void smc_fetch_response(struct scmi_chan_info *cinfo,
252 struct scmi_xfer *xfer)
253 {
254 struct scmi_smc *scmi_info = cinfo->transport_info;
255
256 core->shmem->fetch_response(scmi_info->shmem, xfer);
257 }
258
smc_mark_txdone(struct scmi_chan_info * cinfo,int ret,struct scmi_xfer * __unused)259 static void smc_mark_txdone(struct scmi_chan_info *cinfo, int ret,
260 struct scmi_xfer *__unused)
261 {
262 struct scmi_smc *scmi_info = cinfo->transport_info;
263
264 smc_channel_lock_release(scmi_info);
265 }
266
267 static const struct scmi_transport_ops scmi_smc_ops = {
268 .chan_available = smc_chan_available,
269 .chan_setup = smc_chan_setup,
270 .chan_free = smc_chan_free,
271 .send_message = smc_send_message,
272 .mark_txdone = smc_mark_txdone,
273 .fetch_response = smc_fetch_response,
274 };
275
276 static struct scmi_desc scmi_smc_desc = {
277 .ops = &scmi_smc_ops,
278 .max_rx_timeout_ms = 30,
279 .max_msg = 20,
280 .max_msg_size = 128,
281 /*
282 * Setting .sync_cmds_atomic_replies to true for SMC assumes that,
283 * once the SMC instruction has completed successfully, the issued
284 * SCMI command would have been already fully processed by the SCMI
285 * platform firmware and so any possible response value expected
286 * for the issued command will be immmediately ready to be fetched
287 * from the shared memory area.
288 */
289 .sync_cmds_completed_on_ret = true,
290 .atomic_enabled = IS_ENABLED(CONFIG_ARM_SCMI_TRANSPORT_SMC_ATOMIC_ENABLE),
291 };
292
293 static const struct of_device_id scmi_of_match[] = {
294 { .compatible = "arm,scmi-smc" },
295 { .compatible = "arm,scmi-smc-param" },
296 { .compatible = "qcom,scmi-smc" },
297 { /* Sentinel */ },
298 };
299
300 DEFINE_SCMI_TRANSPORT_DRIVER(scmi_smc, scmi_smc_driver, scmi_smc_desc,
301 scmi_of_match, core);
302 module_platform_driver(scmi_smc_driver);
303
304 MODULE_AUTHOR("Peng Fan <peng.fan@nxp.com>");
305 MODULE_AUTHOR("Nikunj Kela <quic_nkela@quicinc.com>");
306 MODULE_DESCRIPTION("SCMI SMC Transport driver");
307 MODULE_LICENSE("GPL");
308