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 channel 23 * @cinfo: SCMI channel info 24 * @shmem: Transmit/Receive shared memory area 25 */ 26 struct scmi_mailbox { 27 struct mbox_client cl; 28 struct mbox_chan *chan; 29 struct scmi_chan_info *cinfo; 30 struct scmi_shared_mem __iomem *shmem; 31 }; 32 33 #define client_to_scmi_mailbox(c) container_of(c, struct scmi_mailbox, cl) 34 35 static void tx_prepare(struct mbox_client *cl, void *m) 36 { 37 struct scmi_mailbox *smbox = client_to_scmi_mailbox(cl); 38 39 shmem_tx_prepare(smbox->shmem, m, smbox->cinfo); 40 } 41 42 static void rx_callback(struct mbox_client *cl, void *m) 43 { 44 struct scmi_mailbox *smbox = client_to_scmi_mailbox(cl); 45 46 scmi_rx_callback(smbox->cinfo, shmem_read_header(smbox->shmem), NULL); 47 } 48 49 static bool mailbox_chan_available(struct device_node *of_node, int idx) 50 { 51 return !of_parse_phandle_with_args(of_node, "mboxes", 52 "#mbox-cells", idx, NULL); 53 } 54 55 static int mailbox_chan_setup(struct scmi_chan_info *cinfo, struct device *dev, 56 bool tx) 57 { 58 const char *desc = tx ? "Tx" : "Rx"; 59 struct device *cdev = cinfo->dev; 60 struct scmi_mailbox *smbox; 61 struct device_node *shmem; 62 int ret, idx = tx ? 0 : 1; 63 struct mbox_client *cl; 64 resource_size_t size; 65 struct resource res; 66 67 smbox = devm_kzalloc(dev, sizeof(*smbox), GFP_KERNEL); 68 if (!smbox) 69 return -ENOMEM; 70 71 shmem = of_parse_phandle(cdev->of_node, "shmem", idx); 72 if (!of_device_is_compatible(shmem, "arm,scmi-shmem")) 73 return -ENXIO; 74 75 ret = of_address_to_resource(shmem, 0, &res); 76 of_node_put(shmem); 77 if (ret) { 78 dev_err(cdev, "failed to get SCMI %s shared memory\n", desc); 79 return ret; 80 } 81 82 size = resource_size(&res); 83 smbox->shmem = devm_ioremap(dev, res.start, size); 84 if (!smbox->shmem) { 85 dev_err(dev, "failed to ioremap SCMI %s shared memory\n", desc); 86 return -EADDRNOTAVAIL; 87 } 88 89 cl = &smbox->cl; 90 cl->dev = cdev; 91 cl->tx_prepare = tx ? tx_prepare : NULL; 92 cl->rx_callback = rx_callback; 93 cl->tx_block = false; 94 cl->knows_txdone = tx; 95 96 smbox->chan = mbox_request_channel(cl, tx ? 0 : 1); 97 if (IS_ERR(smbox->chan)) { 98 ret = PTR_ERR(smbox->chan); 99 if (ret != -EPROBE_DEFER) 100 dev_err(cdev, "failed to request SCMI %s mailbox\n", 101 tx ? "Tx" : "Rx"); 102 return ret; 103 } 104 105 cinfo->transport_info = smbox; 106 smbox->cinfo = cinfo; 107 108 return 0; 109 } 110 111 static int mailbox_chan_free(int id, void *p, void *data) 112 { 113 struct scmi_chan_info *cinfo = p; 114 struct scmi_mailbox *smbox = cinfo->transport_info; 115 116 if (smbox && !IS_ERR(smbox->chan)) { 117 mbox_free_channel(smbox->chan); 118 cinfo->transport_info = NULL; 119 smbox->chan = NULL; 120 smbox->cinfo = NULL; 121 } 122 123 return 0; 124 } 125 126 static int mailbox_send_message(struct scmi_chan_info *cinfo, 127 struct scmi_xfer *xfer) 128 { 129 struct scmi_mailbox *smbox = cinfo->transport_info; 130 int ret; 131 132 ret = mbox_send_message(smbox->chan, xfer); 133 134 /* mbox_send_message returns non-negative value on success, so reset */ 135 if (ret > 0) 136 ret = 0; 137 138 return ret; 139 } 140 141 static void mailbox_mark_txdone(struct scmi_chan_info *cinfo, int ret, 142 struct scmi_xfer *__unused) 143 { 144 struct scmi_mailbox *smbox = cinfo->transport_info; 145 146 /* 147 * NOTE: we might prefer not to need the mailbox ticker to manage the 148 * transfer queueing since the protocol layer queues things by itself. 149 * Unfortunately, we have to kick the mailbox framework after we have 150 * received our message. 151 */ 152 mbox_client_txdone(smbox->chan, ret); 153 } 154 155 static void mailbox_fetch_response(struct scmi_chan_info *cinfo, 156 struct scmi_xfer *xfer) 157 { 158 struct scmi_mailbox *smbox = cinfo->transport_info; 159 160 shmem_fetch_response(smbox->shmem, xfer); 161 } 162 163 static void mailbox_fetch_notification(struct scmi_chan_info *cinfo, 164 size_t max_len, struct scmi_xfer *xfer) 165 { 166 struct scmi_mailbox *smbox = cinfo->transport_info; 167 168 shmem_fetch_notification(smbox->shmem, max_len, xfer); 169 } 170 171 static void mailbox_clear_channel(struct scmi_chan_info *cinfo) 172 { 173 struct scmi_mailbox *smbox = cinfo->transport_info; 174 175 shmem_clear_channel(smbox->shmem); 176 } 177 178 static bool 179 mailbox_poll_done(struct scmi_chan_info *cinfo, struct scmi_xfer *xfer) 180 { 181 struct scmi_mailbox *smbox = cinfo->transport_info; 182 183 return shmem_poll_done(smbox->shmem, xfer); 184 } 185 186 static const struct scmi_transport_ops scmi_mailbox_ops = { 187 .chan_available = mailbox_chan_available, 188 .chan_setup = mailbox_chan_setup, 189 .chan_free = mailbox_chan_free, 190 .send_message = mailbox_send_message, 191 .mark_txdone = mailbox_mark_txdone, 192 .fetch_response = mailbox_fetch_response, 193 .fetch_notification = mailbox_fetch_notification, 194 .clear_channel = mailbox_clear_channel, 195 .poll_done = mailbox_poll_done, 196 }; 197 198 const struct scmi_desc scmi_mailbox_desc = { 199 .ops = &scmi_mailbox_ops, 200 .max_rx_timeout_ms = 30, /* We may increase this if required */ 201 .max_msg = 20, /* Limited by MBOX_TX_QUEUE_LEN */ 202 .max_msg_size = 128, 203 }; 204