1 // SPDX-License-Identifier: GPL-2.0 2 /* 3 * System Control and Management Interface (SCMI) Message Mailbox Transport 4 * driver. 5 * 6 * Copyright (C) 2019 ARM Ltd. 7 */ 8 9 #include <linux/err.h> 10 #include <linux/device.h> 11 #include <linux/mailbox_client.h> 12 #include <linux/of.h> 13 #include <linux/of_address.h> 14 #include <linux/slab.h> 15 16 #include "common.h" 17 18 /** 19 * struct scmi_mailbox - Structure representing a SCMI mailbox transport 20 * 21 * @cl: Mailbox Client 22 * @chan: Transmit/Receive mailbox uni/bi-directional channel 23 * @chan_receiver: Optional Receiver mailbox unidirectional channel 24 * @cinfo: SCMI channel info 25 * @shmem: Transmit/Receive shared memory area 26 */ 27 struct scmi_mailbox { 28 struct mbox_client cl; 29 struct mbox_chan *chan; 30 struct mbox_chan *chan_receiver; 31 struct scmi_chan_info *cinfo; 32 struct scmi_shared_mem __iomem *shmem; 33 }; 34 35 #define client_to_scmi_mailbox(c) container_of(c, struct scmi_mailbox, cl) 36 37 static void tx_prepare(struct mbox_client *cl, void *m) 38 { 39 struct scmi_mailbox *smbox = client_to_scmi_mailbox(cl); 40 41 shmem_tx_prepare(smbox->shmem, m, smbox->cinfo); 42 } 43 44 static void rx_callback(struct mbox_client *cl, void *m) 45 { 46 struct scmi_mailbox *smbox = client_to_scmi_mailbox(cl); 47 48 /* 49 * An A2P IRQ is NOT valid when received while the platform still has 50 * the ownership of the channel, because the platform at first releases 51 * the SMT channel and then sends the completion interrupt. 52 * 53 * This addresses a possible race condition in which a spurious IRQ from 54 * a previous timed-out reply which arrived late could be wrongly 55 * associated with the next pending transaction. 56 */ 57 if (cl->knows_txdone && !shmem_channel_free(smbox->shmem)) { 58 dev_warn(smbox->cinfo->dev, "Ignoring spurious A2P IRQ !\n"); 59 return; 60 } 61 62 scmi_rx_callback(smbox->cinfo, shmem_read_header(smbox->shmem), NULL); 63 } 64 65 static bool mailbox_chan_available(struct device_node *of_node, int idx) 66 { 67 int num_mb; 68 69 /* 70 * Just check if bidirrectional channels are involved, and check the 71 * index accordingly; proper full validation will be made later 72 * in mailbox_chan_setup(). 73 */ 74 num_mb = of_count_phandle_with_args(of_node, "mboxes", "#mbox-cells"); 75 if (num_mb == 3 && idx == 1) 76 idx = 2; 77 78 return !of_parse_phandle_with_args(of_node, "mboxes", 79 "#mbox-cells", idx, NULL); 80 } 81 82 /** 83 * mailbox_chan_validate - Validate transport configuration and map channels 84 * 85 * @cdev: Reference to the underlying transport device carrying the 86 * of_node descriptor to analyze. 87 * @a2p_rx_chan: A reference to an optional unidirectional channel to use 88 * for replies on the a2p channel. Set as zero if not present. 89 * @p2a_chan: A reference to the optional p2a channel. 90 * Set as zero if not present. 91 * 92 * At first, validate the transport configuration as described in terms of 93 * 'mboxes' and 'shmem', then determin which mailbox channel indexes are 94 * appropriate to be use in the current configuration. 95 * 96 * Return: 0 on Success or error 97 */ 98 static int mailbox_chan_validate(struct device *cdev, 99 int *a2p_rx_chan, int *p2a_chan) 100 { 101 int num_mb, num_sh, ret = 0; 102 struct device_node *np = cdev->of_node; 103 104 num_mb = of_count_phandle_with_args(np, "mboxes", "#mbox-cells"); 105 num_sh = of_count_phandle_with_args(np, "shmem", NULL); 106 dev_dbg(cdev, "Found %d mboxes and %d shmems !\n", num_mb, num_sh); 107 108 /* Bail out if mboxes and shmem descriptors are inconsistent */ 109 if (num_mb <= 0 || num_sh <= 0 || num_sh > 2 || num_mb > 3 || 110 (num_mb == 1 && num_sh != 1) || (num_mb == 3 && num_sh != 2)) { 111 dev_warn(cdev, 112 "Invalid channel descriptor for '%s' - mbs:%d shm:%d\n", 113 of_node_full_name(np), num_mb, num_sh); 114 return -EINVAL; 115 } 116 117 /* Bail out if provided shmem descriptors do not refer distinct areas */ 118 if (num_sh > 1) { 119 struct device_node *np_tx, *np_rx; 120 121 np_tx = of_parse_phandle(np, "shmem", 0); 122 np_rx = of_parse_phandle(np, "shmem", 1); 123 if (!np_tx || !np_rx || np_tx == np_rx) { 124 dev_warn(cdev, "Invalid shmem descriptor for '%s'\n", 125 of_node_full_name(np)); 126 ret = -EINVAL; 127 } 128 129 of_node_put(np_tx); 130 of_node_put(np_rx); 131 } 132 133 /* Calculate channels IDs to use depending on mboxes/shmem layout */ 134 if (!ret) { 135 switch (num_mb) { 136 case 1: 137 *a2p_rx_chan = 0; 138 *p2a_chan = 0; 139 break; 140 case 2: 141 if (num_sh == 2) { 142 *a2p_rx_chan = 0; 143 *p2a_chan = 1; 144 } else { 145 *a2p_rx_chan = 1; 146 *p2a_chan = 0; 147 } 148 break; 149 case 3: 150 *a2p_rx_chan = 1; 151 *p2a_chan = 2; 152 break; 153 } 154 } 155 156 return ret; 157 } 158 159 static int mailbox_chan_setup(struct scmi_chan_info *cinfo, struct device *dev, 160 bool tx) 161 { 162 const char *desc = tx ? "Tx" : "Rx"; 163 struct device *cdev = cinfo->dev; 164 struct scmi_mailbox *smbox; 165 struct device_node *shmem; 166 int ret, a2p_rx_chan, p2a_chan, idx = tx ? 0 : 1; 167 struct mbox_client *cl; 168 resource_size_t size; 169 struct resource res; 170 171 ret = mailbox_chan_validate(cdev, &a2p_rx_chan, &p2a_chan); 172 if (ret) 173 return ret; 174 175 if (!tx && !p2a_chan) 176 return -ENODEV; 177 178 smbox = devm_kzalloc(dev, sizeof(*smbox), GFP_KERNEL); 179 if (!smbox) 180 return -ENOMEM; 181 182 shmem = of_parse_phandle(cdev->of_node, "shmem", idx); 183 if (!of_device_is_compatible(shmem, "arm,scmi-shmem")) { 184 of_node_put(shmem); 185 return -ENXIO; 186 } 187 188 ret = of_address_to_resource(shmem, 0, &res); 189 of_node_put(shmem); 190 if (ret) { 191 dev_err(cdev, "failed to get SCMI %s shared memory\n", desc); 192 return ret; 193 } 194 195 size = resource_size(&res); 196 smbox->shmem = devm_ioremap(dev, res.start, size); 197 if (!smbox->shmem) { 198 dev_err(dev, "failed to ioremap SCMI %s shared memory\n", desc); 199 return -EADDRNOTAVAIL; 200 } 201 202 cl = &smbox->cl; 203 cl->dev = cdev; 204 cl->tx_prepare = tx ? tx_prepare : NULL; 205 cl->rx_callback = rx_callback; 206 cl->tx_block = false; 207 cl->knows_txdone = tx; 208 209 smbox->chan = mbox_request_channel(cl, tx ? 0 : p2a_chan); 210 if (IS_ERR(smbox->chan)) { 211 ret = PTR_ERR(smbox->chan); 212 if (ret != -EPROBE_DEFER) 213 dev_err(cdev, 214 "failed to request SCMI %s mailbox\n", desc); 215 return ret; 216 } 217 218 /* Additional unidirectional channel for TX if needed */ 219 if (tx && a2p_rx_chan) { 220 smbox->chan_receiver = mbox_request_channel(cl, a2p_rx_chan); 221 if (IS_ERR(smbox->chan_receiver)) { 222 ret = PTR_ERR(smbox->chan_receiver); 223 if (ret != -EPROBE_DEFER) 224 dev_err(cdev, "failed to request SCMI Tx Receiver mailbox\n"); 225 return ret; 226 } 227 } 228 229 cinfo->transport_info = smbox; 230 smbox->cinfo = cinfo; 231 232 return 0; 233 } 234 235 static int mailbox_chan_free(int id, void *p, void *data) 236 { 237 struct scmi_chan_info *cinfo = p; 238 struct scmi_mailbox *smbox = cinfo->transport_info; 239 240 if (smbox && !IS_ERR(smbox->chan)) { 241 mbox_free_channel(smbox->chan); 242 mbox_free_channel(smbox->chan_receiver); 243 cinfo->transport_info = NULL; 244 smbox->chan = NULL; 245 smbox->chan_receiver = NULL; 246 smbox->cinfo = NULL; 247 } 248 249 return 0; 250 } 251 252 static int mailbox_send_message(struct scmi_chan_info *cinfo, 253 struct scmi_xfer *xfer) 254 { 255 struct scmi_mailbox *smbox = cinfo->transport_info; 256 int ret; 257 258 ret = mbox_send_message(smbox->chan, xfer); 259 260 /* mbox_send_message returns non-negative value on success, so reset */ 261 if (ret > 0) 262 ret = 0; 263 264 return ret; 265 } 266 267 static void mailbox_mark_txdone(struct scmi_chan_info *cinfo, int ret, 268 struct scmi_xfer *__unused) 269 { 270 struct scmi_mailbox *smbox = cinfo->transport_info; 271 272 /* 273 * NOTE: we might prefer not to need the mailbox ticker to manage the 274 * transfer queueing since the protocol layer queues things by itself. 275 * Unfortunately, we have to kick the mailbox framework after we have 276 * received our message. 277 */ 278 mbox_client_txdone(smbox->chan, ret); 279 } 280 281 static void mailbox_fetch_response(struct scmi_chan_info *cinfo, 282 struct scmi_xfer *xfer) 283 { 284 struct scmi_mailbox *smbox = cinfo->transport_info; 285 286 shmem_fetch_response(smbox->shmem, xfer); 287 } 288 289 static void mailbox_fetch_notification(struct scmi_chan_info *cinfo, 290 size_t max_len, struct scmi_xfer *xfer) 291 { 292 struct scmi_mailbox *smbox = cinfo->transport_info; 293 294 shmem_fetch_notification(smbox->shmem, max_len, xfer); 295 } 296 297 static void mailbox_clear_channel(struct scmi_chan_info *cinfo) 298 { 299 struct scmi_mailbox *smbox = cinfo->transport_info; 300 301 shmem_clear_channel(smbox->shmem); 302 } 303 304 static bool 305 mailbox_poll_done(struct scmi_chan_info *cinfo, struct scmi_xfer *xfer) 306 { 307 struct scmi_mailbox *smbox = cinfo->transport_info; 308 309 return shmem_poll_done(smbox->shmem, xfer); 310 } 311 312 static const struct scmi_transport_ops scmi_mailbox_ops = { 313 .chan_available = mailbox_chan_available, 314 .chan_setup = mailbox_chan_setup, 315 .chan_free = mailbox_chan_free, 316 .send_message = mailbox_send_message, 317 .mark_txdone = mailbox_mark_txdone, 318 .fetch_response = mailbox_fetch_response, 319 .fetch_notification = mailbox_fetch_notification, 320 .clear_channel = mailbox_clear_channel, 321 .poll_done = mailbox_poll_done, 322 }; 323 324 const struct scmi_desc scmi_mailbox_desc = { 325 .ops = &scmi_mailbox_ops, 326 .max_rx_timeout_ms = 30, /* We may increase this if required */ 327 .max_msg = 20, /* Limited by MBOX_TX_QUEUE_LEN */ 328 .max_msg_size = 128, 329 }; 330