1 // SPDX-License-Identifier: GPL-2.0-only
2 /* Copyright (c) 2010,2015,2019 The Linux Foundation. All rights reserved.
3  * Copyright (C) 2015 Linaro Ltd.
4  */
5 
6 #include <linux/slab.h>
7 #include <linux/io.h>
8 #include <linux/module.h>
9 #include <linux/mutex.h>
10 #include <linux/errno.h>
11 #include <linux/err.h>
12 #include <linux/qcom_scm.h>
13 #include <linux/arm-smccc.h>
14 #include <linux/dma-mapping.h>
15 
16 #include "qcom_scm.h"
17 
18 static DEFINE_MUTEX(qcom_scm_lock);
19 
20 
21 /**
22  * struct arm_smccc_args
23  * @args:	The array of values used in registers in smc instruction
24  */
25 struct arm_smccc_args {
26 	unsigned long args[8];
27 };
28 
29 
30 /**
31  * struct scm_legacy_command - one SCM command buffer
32  * @len: total available memory for command and response
33  * @buf_offset: start of command buffer
34  * @resp_hdr_offset: start of response buffer
35  * @id: command to be executed
36  * @buf: buffer returned from scm_legacy_get_command_buffer()
37  *
38  * An SCM command is laid out in memory as follows:
39  *
40  *	------------------- <--- struct scm_legacy_command
41  *	| command header  |
42  *	------------------- <--- scm_legacy_get_command_buffer()
43  *	| command buffer  |
44  *	------------------- <--- struct scm_legacy_response and
45  *	| response header |      scm_legacy_command_to_response()
46  *	------------------- <--- scm_legacy_get_response_buffer()
47  *	| response buffer |
48  *	-------------------
49  *
50  * There can be arbitrary padding between the headers and buffers so
51  * you should always use the appropriate scm_legacy_get_*_buffer() routines
52  * to access the buffers in a safe manner.
53  */
54 struct scm_legacy_command {
55 	__le32 len;
56 	__le32 buf_offset;
57 	__le32 resp_hdr_offset;
58 	__le32 id;
59 	__le32 buf[];
60 };
61 
62 /**
63  * struct scm_legacy_response - one SCM response buffer
64  * @len: total available memory for response
65  * @buf_offset: start of response data relative to start of scm_legacy_response
66  * @is_complete: indicates if the command has finished processing
67  */
68 struct scm_legacy_response {
69 	__le32 len;
70 	__le32 buf_offset;
71 	__le32 is_complete;
72 };
73 
74 /**
75  * scm_legacy_command_to_response() - Get a pointer to a scm_legacy_response
76  * @cmd: command
77  *
78  * Returns a pointer to a response for a command.
79  */
80 static inline struct scm_legacy_response *scm_legacy_command_to_response(
81 		const struct scm_legacy_command *cmd)
82 {
83 	return (void *)cmd + le32_to_cpu(cmd->resp_hdr_offset);
84 }
85 
86 /**
87  * scm_legacy_get_command_buffer() - Get a pointer to a command buffer
88  * @cmd: command
89  *
90  * Returns a pointer to the command buffer of a command.
91  */
92 static inline void *scm_legacy_get_command_buffer(
93 		const struct scm_legacy_command *cmd)
94 {
95 	return (void *)cmd->buf;
96 }
97 
98 /**
99  * scm_legacy_get_response_buffer() - Get a pointer to a response buffer
100  * @rsp: response
101  *
102  * Returns a pointer to a response buffer of a response.
103  */
104 static inline void *scm_legacy_get_response_buffer(
105 		const struct scm_legacy_response *rsp)
106 {
107 	return (void *)rsp + le32_to_cpu(rsp->buf_offset);
108 }
109 
110 static void __scm_legacy_do(const struct arm_smccc_args *smc,
111 			    struct arm_smccc_res *res)
112 {
113 	do {
114 		arm_smccc_smc(smc->args[0], smc->args[1], smc->args[2],
115 			      smc->args[3], smc->args[4], smc->args[5],
116 			      smc->args[6], smc->args[7], res);
117 	} while (res->a0 == QCOM_SCM_INTERRUPTED);
118 }
119 
120 /**
121  * qcom_scm_call() - Sends a command to the SCM and waits for the command to
122  * finish processing.
123  *
124  * A note on cache maintenance:
125  * Note that any buffers that are expected to be accessed by the secure world
126  * must be flushed before invoking qcom_scm_call and invalidated in the cache
127  * immediately after qcom_scm_call returns. Cache maintenance on the command
128  * and response buffers is taken care of by qcom_scm_call; however, callers are
129  * responsible for any other cached buffers passed over to the secure world.
130  */
131 int scm_legacy_call(struct device *dev, const struct qcom_scm_desc *desc,
132 		    struct qcom_scm_res *res)
133 {
134 	u8 arglen = desc->arginfo & 0xf;
135 	int ret = 0, context_id;
136 	unsigned int i;
137 	struct scm_legacy_command *cmd;
138 	struct scm_legacy_response *rsp;
139 	struct arm_smccc_args smc = {0};
140 	struct arm_smccc_res smc_res;
141 	const size_t cmd_len = arglen * sizeof(__le32);
142 	const size_t resp_len = MAX_QCOM_SCM_RETS * sizeof(__le32);
143 	size_t alloc_len = sizeof(*cmd) + cmd_len + sizeof(*rsp) + resp_len;
144 	dma_addr_t cmd_phys;
145 	__le32 *arg_buf;
146 	const __le32 *res_buf;
147 
148 	cmd = kzalloc(PAGE_ALIGN(alloc_len), GFP_KERNEL);
149 	if (!cmd)
150 		return -ENOMEM;
151 
152 	cmd->len = cpu_to_le32(alloc_len);
153 	cmd->buf_offset = cpu_to_le32(sizeof(*cmd));
154 	cmd->resp_hdr_offset = cpu_to_le32(sizeof(*cmd) + cmd_len);
155 	cmd->id = cpu_to_le32(SCM_LEGACY_FNID(desc->svc, desc->cmd));
156 
157 	arg_buf = scm_legacy_get_command_buffer(cmd);
158 	for (i = 0; i < arglen; i++)
159 		arg_buf[i] = cpu_to_le32(desc->args[i]);
160 
161 	rsp = scm_legacy_command_to_response(cmd);
162 
163 	cmd_phys = dma_map_single(dev, cmd, alloc_len, DMA_TO_DEVICE);
164 	if (dma_mapping_error(dev, cmd_phys)) {
165 		kfree(cmd);
166 		return -ENOMEM;
167 	}
168 
169 	smc.args[0] = 1;
170 	smc.args[1] = (unsigned long)&context_id;
171 	smc.args[2] = cmd_phys;
172 
173 	mutex_lock(&qcom_scm_lock);
174 	__scm_legacy_do(&smc, &smc_res);
175 	if (smc_res.a0)
176 		ret = qcom_scm_remap_error(smc_res.a0);
177 	mutex_unlock(&qcom_scm_lock);
178 	if (ret)
179 		goto out;
180 
181 	do {
182 		dma_sync_single_for_cpu(dev, cmd_phys + sizeof(*cmd) + cmd_len,
183 					sizeof(*rsp), DMA_FROM_DEVICE);
184 	} while (!rsp->is_complete);
185 
186 	dma_sync_single_for_cpu(dev, cmd_phys + sizeof(*cmd) + cmd_len +
187 				le32_to_cpu(rsp->buf_offset),
188 				resp_len, DMA_FROM_DEVICE);
189 
190 	if (res) {
191 		res_buf = scm_legacy_get_response_buffer(rsp);
192 		for (i = 0; i < MAX_QCOM_SCM_RETS; i++)
193 			res->result[i] = le32_to_cpu(res_buf[i]);
194 	}
195 out:
196 	dma_unmap_single(dev, cmd_phys, alloc_len, DMA_TO_DEVICE);
197 	kfree(cmd);
198 	return ret;
199 }
200 
201 #define SCM_LEGACY_ATOMIC_N_REG_ARGS	5
202 #define SCM_LEGACY_ATOMIC_FIRST_REG_IDX	2
203 #define SCM_LEGACY_CLASS_REGISTER		(0x2 << 8)
204 #define SCM_LEGACY_MASK_IRQS		BIT(5)
205 #define SCM_LEGACY_ATOMIC_ID(svc, cmd, n) \
206 				((SCM_LEGACY_FNID(svc, cmd) << 12) | \
207 				SCM_LEGACY_CLASS_REGISTER | \
208 				SCM_LEGACY_MASK_IRQS | \
209 				(n & 0xf))
210 
211 /**
212  * qcom_scm_call_atomic() - Send an atomic SCM command with up to 5 arguments
213  * and 3 return values
214  * @desc: SCM call descriptor containing arguments
215  * @res:  SCM call return values
216  *
217  * This shall only be used with commands that are guaranteed to be
218  * uninterruptable, atomic and SMP safe.
219  */
220 int scm_legacy_call_atomic(struct device *unused,
221 			   const struct qcom_scm_desc *desc,
222 			   struct qcom_scm_res *res)
223 {
224 	int context_id;
225 	struct arm_smccc_res smc_res;
226 	size_t arglen = desc->arginfo & 0xf;
227 
228 	BUG_ON(arglen > SCM_LEGACY_ATOMIC_N_REG_ARGS);
229 
230 	arm_smccc_smc(SCM_LEGACY_ATOMIC_ID(desc->svc, desc->cmd, arglen),
231 		      (unsigned long)&context_id,
232 		      desc->args[0], desc->args[1], desc->args[2],
233 		      desc->args[3], desc->args[4], 0, &smc_res);
234 
235 	if (res) {
236 		res->result[0] = smc_res.a1;
237 		res->result[1] = smc_res.a2;
238 		res->result[2] = smc_res.a3;
239 	}
240 
241 	return smc_res.a0;
242 }
243