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); 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)); 47 } 48 49 static bool mailbox_chan_available(struct device *dev, int idx) 50 { 51 return !of_parse_phandle_with_args(dev->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 ret = of_address_to_resource(shmem, 0, &res); 73 of_node_put(shmem); 74 if (ret) { 75 dev_err(cdev, "failed to get SCMI %s shared memory\n", desc); 76 return ret; 77 } 78 79 size = resource_size(&res); 80 smbox->shmem = devm_ioremap(dev, res.start, size); 81 if (!smbox->shmem) { 82 dev_err(dev, "failed to ioremap SCMI %s shared memory\n", desc); 83 return -EADDRNOTAVAIL; 84 } 85 86 cl = &smbox->cl; 87 cl->dev = cdev; 88 cl->tx_prepare = tx ? tx_prepare : NULL; 89 cl->rx_callback = rx_callback; 90 cl->tx_block = false; 91 cl->knows_txdone = tx; 92 93 smbox->chan = mbox_request_channel(cl, tx ? 0 : 1); 94 if (IS_ERR(smbox->chan)) { 95 ret = PTR_ERR(smbox->chan); 96 if (ret != -EPROBE_DEFER) 97 dev_err(cdev, "failed to request SCMI %s mailbox\n", 98 tx ? "Tx" : "Rx"); 99 return ret; 100 } 101 102 cinfo->transport_info = smbox; 103 smbox->cinfo = cinfo; 104 105 return 0; 106 } 107 108 static int mailbox_chan_free(int id, void *p, void *data) 109 { 110 struct scmi_chan_info *cinfo = p; 111 struct scmi_mailbox *smbox = cinfo->transport_info; 112 113 if (!IS_ERR(smbox->chan)) { 114 mbox_free_channel(smbox->chan); 115 cinfo->transport_info = NULL; 116 smbox->chan = NULL; 117 smbox->cinfo = NULL; 118 } 119 120 scmi_free_channel(cinfo, data, id); 121 122 return 0; 123 } 124 125 static int mailbox_send_message(struct scmi_chan_info *cinfo, 126 struct scmi_xfer *xfer) 127 { 128 struct scmi_mailbox *smbox = cinfo->transport_info; 129 int ret; 130 131 ret = mbox_send_message(smbox->chan, xfer); 132 133 /* mbox_send_message returns non-negative value on success, so reset */ 134 if (ret > 0) 135 ret = 0; 136 137 return ret; 138 } 139 140 static void mailbox_mark_txdone(struct scmi_chan_info *cinfo, int ret) 141 { 142 struct scmi_mailbox *smbox = cinfo->transport_info; 143 144 /* 145 * NOTE: we might prefer not to need the mailbox ticker to manage the 146 * transfer queueing since the protocol layer queues things by itself. 147 * Unfortunately, we have to kick the mailbox framework after we have 148 * received our message. 149 */ 150 mbox_client_txdone(smbox->chan, ret); 151 } 152 153 static void mailbox_fetch_response(struct scmi_chan_info *cinfo, 154 struct scmi_xfer *xfer) 155 { 156 struct scmi_mailbox *smbox = cinfo->transport_info; 157 158 shmem_fetch_response(smbox->shmem, xfer); 159 } 160 161 static bool 162 mailbox_poll_done(struct scmi_chan_info *cinfo, struct scmi_xfer *xfer) 163 { 164 struct scmi_mailbox *smbox = cinfo->transport_info; 165 166 return shmem_poll_done(smbox->shmem, xfer); 167 } 168 169 static struct scmi_transport_ops scmi_mailbox_ops = { 170 .chan_available = mailbox_chan_available, 171 .chan_setup = mailbox_chan_setup, 172 .chan_free = mailbox_chan_free, 173 .send_message = mailbox_send_message, 174 .mark_txdone = mailbox_mark_txdone, 175 .fetch_response = mailbox_fetch_response, 176 .poll_done = mailbox_poll_done, 177 }; 178 179 const struct scmi_desc scmi_mailbox_desc = { 180 .ops = &scmi_mailbox_ops, 181 .max_rx_timeout_ms = 30, /* We may increase this if required */ 182 .max_msg = 20, /* Limited by MBOX_TX_QUEUE_LEN */ 183 .max_msg_size = 128, 184 }; 185