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/device.h>
11#include <linux/err.h>
12#include <linux/mutex.h>
13#include <linux/of.h>
14#include <linux/of_address.h>
15#include <linux/slab.h>
16
17#include "common.h"
18
19/**
20 * struct scmi_smc - Structure representing a SCMI smc transport
21 *
22 * @cinfo: SCMI channel info
23 * @shmem: Transmit/Receive shared memory area
24 * @shmem_lock: Lock to protect access to Tx/Rx shared memory area
25 * @func_id: smc/hvc call function id
26 */
27
28struct scmi_smc {
29	struct scmi_chan_info *cinfo;
30	struct scmi_shared_mem __iomem *shmem;
31	struct mutex shmem_lock;
32	u32 func_id;
33};
34
35static bool smc_chan_available(struct device *dev, int idx)
36{
37	struct device_node *np = of_parse_phandle(dev->of_node, "shmem", 0);
38	if (!np)
39		return false;
40
41	of_node_put(np);
42	return true;
43}
44
45static int smc_chan_setup(struct scmi_chan_info *cinfo, struct device *dev,
46			  bool tx)
47{
48	struct device *cdev = cinfo->dev;
49	struct scmi_smc *scmi_info;
50	resource_size_t size;
51	struct resource res;
52	struct device_node *np;
53	u32 func_id;
54	int ret;
55
56	if (!tx)
57		return -ENODEV;
58
59	scmi_info = devm_kzalloc(dev, sizeof(*scmi_info), GFP_KERNEL);
60	if (!scmi_info)
61		return -ENOMEM;
62
63	np = of_parse_phandle(cdev->of_node, "shmem", 0);
64	ret = of_address_to_resource(np, 0, &res);
65	of_node_put(np);
66	if (ret) {
67		dev_err(cdev, "failed to get SCMI Tx shared memory\n");
68		return ret;
69	}
70
71	size = resource_size(&res);
72	scmi_info->shmem = devm_ioremap(dev, res.start, size);
73	if (!scmi_info->shmem) {
74		dev_err(dev, "failed to ioremap SCMI Tx shared memory\n");
75		return -EADDRNOTAVAIL;
76	}
77
78	ret = of_property_read_u32(dev->of_node, "arm,smc-id", &func_id);
79	if (ret < 0)
80		return ret;
81
82	scmi_info->func_id = func_id;
83	scmi_info->cinfo = cinfo;
84	mutex_init(&scmi_info->shmem_lock);
85	cinfo->transport_info = scmi_info;
86
87	return 0;
88}
89
90static int smc_chan_free(int id, void *p, void *data)
91{
92	struct scmi_chan_info *cinfo = p;
93	struct scmi_smc *scmi_info = cinfo->transport_info;
94
95	cinfo->transport_info = NULL;
96	scmi_info->cinfo = NULL;
97
98	scmi_free_channel(cinfo, data, id);
99
100	return 0;
101}
102
103static int smc_send_message(struct scmi_chan_info *cinfo,
104			    struct scmi_xfer *xfer)
105{
106	struct scmi_smc *scmi_info = cinfo->transport_info;
107	struct arm_smccc_res res;
108
109	mutex_lock(&scmi_info->shmem_lock);
110
111	shmem_tx_prepare(scmi_info->shmem, xfer);
112
113	arm_smccc_1_1_invoke(scmi_info->func_id, 0, 0, 0, 0, 0, 0, 0, &res);
114	scmi_rx_callback(scmi_info->cinfo, shmem_read_header(scmi_info->shmem));
115
116	mutex_unlock(&scmi_info->shmem_lock);
117
118	/* Only SMCCC_RET_NOT_SUPPORTED is valid error code */
119	if (res.a0)
120		return -EOPNOTSUPP;
121	return 0;
122}
123
124static void smc_fetch_response(struct scmi_chan_info *cinfo,
125			       struct scmi_xfer *xfer)
126{
127	struct scmi_smc *scmi_info = cinfo->transport_info;
128
129	shmem_fetch_response(scmi_info->shmem, xfer);
130}
131
132static bool
133smc_poll_done(struct scmi_chan_info *cinfo, struct scmi_xfer *xfer)
134{
135	struct scmi_smc *scmi_info = cinfo->transport_info;
136
137	return shmem_poll_done(scmi_info->shmem, xfer);
138}
139
140static const struct scmi_transport_ops scmi_smc_ops = {
141	.chan_available = smc_chan_available,
142	.chan_setup = smc_chan_setup,
143	.chan_free = smc_chan_free,
144	.send_message = smc_send_message,
145	.fetch_response = smc_fetch_response,
146	.poll_done = smc_poll_done,
147};
148
149const struct scmi_desc scmi_smc_desc = {
150	.ops = &scmi_smc_ops,
151	.max_rx_timeout_ms = 30,
152	.max_msg = 20,
153	.max_msg_size = 128,
154};
155