summaryrefslogtreecommitdiff
path: root/drivers/firmware/arm_scmi/smc.c
blob: 745acfdd0b3dfb2cba2668b1afeed35a9cfef2aa (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
// SPDX-License-Identifier: GPL-2.0
/*
 * System Control and Management Interface (SCMI) Message SMC/HVC
 * Transport driver
 *
 * Copyright 2020 NXP
 */

#include <linux/arm-smccc.h>
#include <linux/atomic.h>
#include <linux/device.h>
#include <linux/err.h>
#include <linux/interrupt.h>
#include <linux/mutex.h>
#include <linux/of.h>
#include <linux/of_address.h>
#include <linux/of_irq.h>
#include <linux/processor.h>
#include <linux/slab.h>

#include "common.h"

/**
 * struct scmi_smc - Structure representing a SCMI smc transport
 *
 * @cinfo: SCMI channel info
 * @shmem: Transmit/Receive shared memory area
 * @shmem_lock: Lock to protect access to Tx/Rx shared memory area.
 *		Used when NOT operating in atomic mode.
 * @inflight: Atomic flag to protect access to Tx/Rx shared memory area.
 *	      Used when operating in atomic mode.
 * @func_id: smc/hvc call function id
 */

struct scmi_smc {
	struct scmi_chan_info *cinfo;
	struct scmi_shared_mem __iomem *shmem;
	/* Protect access to shmem area */
	struct mutex shmem_lock;
#define INFLIGHT_NONE	MSG_TOKEN_MAX
	atomic_t inflight;
	u32 func_id;
};

static irqreturn_t smc_msg_done_isr(int irq, void *data)
{
	struct scmi_smc *scmi_info = data;

	scmi_rx_callback(scmi_info->cinfo,
			 shmem_read_header(scmi_info->shmem), NULL);

	return IRQ_HANDLED;
}

static bool smc_chan_available(struct device *dev, int idx)
{
	struct device_node *np = of_parse_phandle(dev->of_node, "shmem", 0);
	if (!np)
		return false;

	of_node_put(np);
	return true;
}

static inline void smc_channel_lock_init(struct scmi_smc *scmi_info)
{
	if (IS_ENABLED(CONFIG_ARM_SCMI_TRANSPORT_SMC_ATOMIC_ENABLE))
		atomic_set(&scmi_info->inflight, INFLIGHT_NONE);
	else
		mutex_init(&scmi_info->shmem_lock);
}

static bool smc_xfer_inflight(struct scmi_xfer *xfer, atomic_t *inflight)
{
	int ret;

	ret = atomic_cmpxchg(inflight, INFLIGHT_NONE, xfer->hdr.seq);

	return ret == INFLIGHT_NONE;
}

static inline void
smc_channel_lock_acquire(struct scmi_smc *scmi_info,
			 struct scmi_xfer *xfer __maybe_unused)
{
	if (IS_ENABLED(CONFIG_ARM_SCMI_TRANSPORT_SMC_ATOMIC_ENABLE))
		spin_until_cond(smc_xfer_inflight(xfer, &scmi_info->inflight));
	else
		mutex_lock(&scmi_info->shmem_lock);
}

static inline void smc_channel_lock_release(struct scmi_smc *scmi_info)
{
	if (IS_ENABLED(CONFIG_ARM_SCMI_TRANSPORT_SMC_ATOMIC_ENABLE))
		atomic_set(&scmi_info->inflight, INFLIGHT_NONE);
	else
		mutex_unlock(&scmi_info->shmem_lock);
}

static int smc_chan_setup(struct scmi_chan_info *cinfo, struct device *dev,
			  bool tx)
{
	struct device *cdev = cinfo->dev;
	struct scmi_smc *scmi_info;
	resource_size_t size;
	struct resource res;
	struct device_node *np;
	u32 func_id;
	int ret, irq;

	if (!tx)
		return -ENODEV;

	scmi_info = devm_kzalloc(dev, sizeof(*scmi_info), GFP_KERNEL);
	if (!scmi_info)
		return -ENOMEM;

	np = of_parse_phandle(cdev->of_node, "shmem", 0);
	if (!of_device_is_compatible(np, "arm,scmi-shmem"))
		return -ENXIO;

	ret = of_address_to_resource(np, 0, &res);
	of_node_put(np);
	if (ret) {
		dev_err(cdev, "failed to get SCMI Tx shared memory\n");
		return ret;
	}

	size = resource_size(&res);
	scmi_info->shmem = devm_ioremap(dev, res.start, size);
	if (!scmi_info->shmem) {
		dev_err(dev, "failed to ioremap SCMI Tx shared memory\n");
		return -EADDRNOTAVAIL;
	}

	ret = of_property_read_u32(dev->of_node, "arm,smc-id", &func_id);
	if (ret < 0)
		return ret;

	/*
	 * If there is an interrupt named "a2p", then the service and
	 * completion of a message is signaled by an interrupt rather than by
	 * the return of the SMC call.
	 */
	irq = of_irq_get_byname(cdev->of_node, "a2p");
	if (irq > 0) {
		ret = devm_request_irq(dev, irq, smc_msg_done_isr,
				       IRQF_NO_SUSPEND,
				       dev_name(dev), scmi_info);
		if (ret) {
			dev_err(dev, "failed to setup SCMI smc irq\n");
			return ret;
		}
	} else {
		cinfo->no_completion_irq = true;
	}

	scmi_info->func_id = func_id;
	scmi_info->cinfo = cinfo;
	smc_channel_lock_init(scmi_info);
	cinfo->transport_info = scmi_info;

	return 0;
}

static int smc_chan_free(int id, void *p, void *data)
{
	struct scmi_chan_info *cinfo = p;
	struct scmi_smc *scmi_info = cinfo->transport_info;

	cinfo->transport_info = NULL;
	scmi_info->cinfo = NULL;

	scmi_free_channel(cinfo, data, id);

	return 0;
}

static int smc_send_message(struct scmi_chan_info *cinfo,
			    struct scmi_xfer *xfer)
{
	struct scmi_smc *scmi_info = cinfo->transport_info;
	struct arm_smccc_res res;

	/*
	 * Channel will be released only once response has been
	 * surely fully retrieved, so after .mark_txdone()
	 */
	smc_channel_lock_acquire(scmi_info, xfer);

	shmem_tx_prepare(scmi_info->shmem, xfer);

	arm_smccc_1_1_invoke(scmi_info->func_id, 0, 0, 0, 0, 0, 0, 0, &res);

	/* Only SMCCC_RET_NOT_SUPPORTED is valid error code */
	if (res.a0) {
		smc_channel_lock_release(scmi_info);
		return -EOPNOTSUPP;
	}

	return 0;
}

static void smc_fetch_response(struct scmi_chan_info *cinfo,
			       struct scmi_xfer *xfer)
{
	struct scmi_smc *scmi_info = cinfo->transport_info;

	shmem_fetch_response(scmi_info->shmem, xfer);
}

static void smc_mark_txdone(struct scmi_chan_info *cinfo, int ret,
			    struct scmi_xfer *__unused)
{
	struct scmi_smc *scmi_info = cinfo->transport_info;

	smc_channel_lock_release(scmi_info);
}

static const struct scmi_transport_ops scmi_smc_ops = {
	.chan_available = smc_chan_available,
	.chan_setup = smc_chan_setup,
	.chan_free = smc_chan_free,
	.send_message = smc_send_message,
	.mark_txdone = smc_mark_txdone,
	.fetch_response = smc_fetch_response,
};

const struct scmi_desc scmi_smc_desc = {
	.ops = &scmi_smc_ops,
	.max_rx_timeout_ms = 30,
	.max_msg = 20,
	.max_msg_size = 128,
	/*
	 * Setting .sync_cmds_atomic_replies to true for SMC assumes that,
	 * once the SMC instruction has completed successfully, the issued
	 * SCMI command would have been already fully processed by the SCMI
	 * platform firmware and so any possible response value expected
	 * for the issued command will be immmediately ready to be fetched
	 * from the shared memory area.
	 */
	.sync_cmds_completed_on_ret = true,
	.atomic_enabled = IS_ENABLED(CONFIG_ARM_SCMI_TRANSPORT_SMC_ATOMIC_ENABLE),
};