smc.c

  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 * @io_ops: Transport specific I/O operations
 49 * @shmem_lock: Lock to protect access to Tx/Rx shared memory area.
 50 *		Used when NOT operating in atomic mode.
 51 * @inflight: Atomic flag to protect access to Tx/Rx shared memory area.
 52 *	      Used when operating in atomic mode.
 53 * @func_id: smc/hvc call function id
 54 * @param_page: 4K page number of the shmem channel
 55 * @param_offset: Offset within the 4K page of the shmem channel
 56 * @cap_id: smc/hvc doorbell's capability id to be used on Qualcomm virtual
 57 *	    platforms
 58 */
 59
 60struct scmi_smc {
 61	int irq;
 62	struct scmi_chan_info *cinfo;
 63	struct scmi_shared_mem __iomem *shmem;
 64	struct scmi_shmem_io_ops *io_ops;
 65	/* Protect access to shmem area */
 66	struct mutex shmem_lock;
 67#define INFLIGHT_NONE	MSG_TOKEN_MAX
 68	atomic_t inflight;
 69	unsigned long func_id;
 70	unsigned long param_page;
 71	unsigned long param_offset;
 72	unsigned long cap_id;
 73};
 74
 75static struct scmi_transport_core_operations *core;
 76
 77static irqreturn_t smc_msg_done_isr(int irq, void *data)
 78{
 79	struct scmi_smc *scmi_info = data;
 80
 81	core->rx_callback(scmi_info->cinfo,
 82			  core->shmem->read_header(scmi_info->shmem), NULL);
 83
 84	return IRQ_HANDLED;
 85}
 86
 87static bool smc_chan_available(struct device_node *of_node, int idx)
 88{
 89	struct device_node *np __free(device_node) =
 90					of_parse_phandle(of_node, "shmem", 0);
 91	if (!np)
 92		return false;
 93
 94	return true;
 95}
 96
 97static inline void smc_channel_lock_init(struct scmi_smc *scmi_info)
 98{
 99	if (IS_ENABLED(CONFIG_ARM_SCMI_TRANSPORT_SMC_ATOMIC_ENABLE))
100		atomic_set(&scmi_info->inflight, INFLIGHT_NONE);
101	else
102		mutex_init(&scmi_info->shmem_lock);
103}
104
105static bool smc_xfer_inflight(struct scmi_xfer *xfer, atomic_t *inflight)
106{
107	int ret;
108
109	ret = atomic_cmpxchg(inflight, INFLIGHT_NONE, xfer->hdr.seq);
110
111	return ret == INFLIGHT_NONE;
112}
113
114static inline void
115smc_channel_lock_acquire(struct scmi_smc *scmi_info,
116			 struct scmi_xfer *xfer __maybe_unused)
117{
118	if (IS_ENABLED(CONFIG_ARM_SCMI_TRANSPORT_SMC_ATOMIC_ENABLE))
119		spin_until_cond(smc_xfer_inflight(xfer, &scmi_info->inflight));
120	else
121		mutex_lock(&scmi_info->shmem_lock);
122}
123
124static inline void smc_channel_lock_release(struct scmi_smc *scmi_info)
125{
126	if (IS_ENABLED(CONFIG_ARM_SCMI_TRANSPORT_SMC_ATOMIC_ENABLE))
127		atomic_set(&scmi_info->inflight, INFLIGHT_NONE);
128	else
129		mutex_unlock(&scmi_info->shmem_lock);
130}
131
132static int smc_chan_setup(struct scmi_chan_info *cinfo, struct device *dev,
133			  bool tx)
134{
135	struct device *cdev = cinfo->dev;
136	unsigned long cap_id = ULONG_MAX;
137	struct scmi_smc *scmi_info;
138	struct resource res = {};
139	u32 func_id;
140	int ret;
141
142	if (!tx)
143		return -ENODEV;
144
145	scmi_info = devm_kzalloc(dev, sizeof(*scmi_info), GFP_KERNEL);
146	if (!scmi_info)
147		return -ENOMEM;
148
149	scmi_info->shmem = core->shmem->setup_iomap(cinfo, dev, tx, &res,
150						    &scmi_info->io_ops);
151	if (IS_ERR(scmi_info->shmem))
152		return PTR_ERR(scmi_info->shmem);
153
154	ret = of_property_read_u32(dev->of_node, "arm,smc-id", &func_id);
155	if (ret < 0)
156		return ret;
157
158	if (of_device_is_compatible(dev->of_node, "qcom,scmi-smc")) {
159		resource_size_t size = resource_size(&res);
160		void __iomem *ptr = (void __iomem *)scmi_info->shmem + size - 8;
161		/* The capability-id is kept in last 8 bytes of shmem.
162		 *     +-------+ <-- 0
163		 *     | shmem |
164		 *     +-------+ <-- size - 8
165		 *     | capId |
166		 *     +-------+ <-- size
167		 */
168		memcpy_fromio(&cap_id, ptr, sizeof(cap_id));
169	}
170
171	if (of_device_is_compatible(dev->of_node, "arm,scmi-smc-param")) {
172		scmi_info->param_page = SHMEM_PAGE(res.start);
173		scmi_info->param_offset = SHMEM_OFFSET(res.start);
174	}
175	/*
176	 * If there is an interrupt named "a2p", then the service and
177	 * completion of a message is signaled by an interrupt rather than by
178	 * the return of the SMC call.
179	 */
180	scmi_info->irq = of_irq_get_byname(cdev->of_node, "a2p");
181	if (scmi_info->irq > 0) {
182		ret = request_irq(scmi_info->irq, smc_msg_done_isr,
183				  IRQF_NO_SUSPEND, dev_name(dev), scmi_info);
184		if (ret) {
185			dev_err(dev, "failed to setup SCMI smc irq\n");
186			return ret;
187		}
188	} else {
189		cinfo->no_completion_irq = true;
190	}
191
192	scmi_info->func_id = func_id;
193	scmi_info->cap_id = cap_id;
194	scmi_info->cinfo = cinfo;
195	smc_channel_lock_init(scmi_info);
196	cinfo->transport_info = scmi_info;
197
198	return 0;
199}
200
201static int smc_chan_free(int id, void *p, void *data)
202{
203	struct scmi_chan_info *cinfo = p;
204	struct scmi_smc *scmi_info = cinfo->transport_info;
205
206	/*
207	 * Different protocols might share the same chan info, so a previous
208	 * smc_chan_free call might have already freed the structure.
209	 */
210	if (!scmi_info)
211		return 0;
212
213	/* Ignore any possible further reception on the IRQ path */
214	if (scmi_info->irq > 0)
215		free_irq(scmi_info->irq, scmi_info);
216
217	cinfo->transport_info = NULL;
218	scmi_info->cinfo = NULL;
219
220	return 0;
221}
222
223static int smc_send_message(struct scmi_chan_info *cinfo,
224			    struct scmi_xfer *xfer)
225{
226	struct scmi_smc *scmi_info = cinfo->transport_info;
227	struct arm_smccc_res res;
228
229	/*
230	 * Channel will be released only once response has been
231	 * surely fully retrieved, so after .mark_txdone()
232	 */
233	smc_channel_lock_acquire(scmi_info, xfer);
234
235	core->shmem->tx_prepare(scmi_info->shmem, xfer, cinfo,
236				scmi_info->io_ops->toio);
237
238	if (scmi_info->cap_id != ULONG_MAX)
239		arm_smccc_1_1_invoke(scmi_info->func_id, scmi_info->cap_id, 0,
240				     0, 0, 0, 0, 0, &res);
241	else
242		arm_smccc_1_1_invoke(scmi_info->func_id, scmi_info->param_page,
243				     scmi_info->param_offset, 0, 0, 0, 0, 0,
244				     &res);
245
246	/* Only SMCCC_RET_NOT_SUPPORTED is valid error code */
247	if (res.a0) {
248		smc_channel_lock_release(scmi_info);
249		return -EOPNOTSUPP;
250	}
251
252	return 0;
253}
254
255static void smc_fetch_response(struct scmi_chan_info *cinfo,
256			       struct scmi_xfer *xfer)
257{
258	struct scmi_smc *scmi_info = cinfo->transport_info;
259
260	core->shmem->fetch_response(scmi_info->shmem, xfer,
261				    scmi_info->io_ops->fromio);
262}
263
264static void smc_mark_txdone(struct scmi_chan_info *cinfo, int ret,
265			    struct scmi_xfer *__unused)
266{
267	struct scmi_smc *scmi_info = cinfo->transport_info;
268
269	smc_channel_lock_release(scmi_info);
270}
271
272static const struct scmi_transport_ops scmi_smc_ops = {
273	.chan_available = smc_chan_available,
274	.chan_setup = smc_chan_setup,
275	.chan_free = smc_chan_free,
276	.send_message = smc_send_message,
277	.mark_txdone = smc_mark_txdone,
278	.fetch_response = smc_fetch_response,
279};
280
281static struct scmi_desc scmi_smc_desc = {
282	.ops = &scmi_smc_ops,
283	.max_rx_timeout_ms = 30,
284	.max_msg = 20,
285	.max_msg_size = SCMI_SHMEM_MAX_PAYLOAD_SIZE,
286	/*
287	 * Setting .sync_cmds_atomic_replies to true for SMC assumes that,
288	 * once the SMC instruction has completed successfully, the issued
289	 * SCMI command would have been already fully processed by the SCMI
290	 * platform firmware and so any possible response value expected
291	 * for the issued command will be immmediately ready to be fetched
292	 * from the shared memory area.
293	 */
294	.sync_cmds_completed_on_ret = true,
295	.atomic_enabled = IS_ENABLED(CONFIG_ARM_SCMI_TRANSPORT_SMC_ATOMIC_ENABLE),
296};
297
298static const struct of_device_id scmi_of_match[] = {
299	{ .compatible = "arm,scmi-smc" },
300	{ .compatible = "arm,scmi-smc-param" },
301	{ .compatible = "qcom,scmi-smc" },
302	{ /* Sentinel */ },
303};
304MODULE_DEVICE_TABLE(of, scmi_of_match);
305
306DEFINE_SCMI_TRANSPORT_DRIVER(scmi_smc, scmi_smc_driver, scmi_smc_desc,
307			     scmi_of_match, core);
308module_platform_driver(scmi_smc_driver);
309
310MODULE_AUTHOR("Peng Fan <peng.fan@nxp.com>");
311MODULE_AUTHOR("Nikunj Kela <quic_nkela@quicinc.com>");
312MODULE_DESCRIPTION("SCMI SMC Transport driver");
313MODULE_LICENSE("GPL");