smc.c (6188B)
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/processor.h> 19#include <linux/slab.h> 20 21#include "common.h" 22 23/** 24 * struct scmi_smc - Structure representing a SCMI smc transport 25 * 26 * @cinfo: SCMI channel info 27 * @shmem: Transmit/Receive shared memory area 28 * @shmem_lock: Lock to protect access to Tx/Rx shared memory area. 29 * Used when NOT operating in atomic mode. 30 * @inflight: Atomic flag to protect access to Tx/Rx shared memory area. 31 * Used when operating in atomic mode. 32 * @func_id: smc/hvc call function id 33 */ 34 35struct scmi_smc { 36 struct scmi_chan_info *cinfo; 37 struct scmi_shared_mem __iomem *shmem; 38 /* Protect access to shmem area */ 39 struct mutex shmem_lock; 40#define INFLIGHT_NONE MSG_TOKEN_MAX 41 atomic_t inflight; 42 u32 func_id; 43}; 44 45static irqreturn_t smc_msg_done_isr(int irq, void *data) 46{ 47 struct scmi_smc *scmi_info = data; 48 49 scmi_rx_callback(scmi_info->cinfo, 50 shmem_read_header(scmi_info->shmem), NULL); 51 52 return IRQ_HANDLED; 53} 54 55static bool smc_chan_available(struct device *dev, int idx) 56{ 57 struct device_node *np = of_parse_phandle(dev->of_node, "shmem", 0); 58 if (!np) 59 return false; 60 61 of_node_put(np); 62 return true; 63} 64 65static inline void smc_channel_lock_init(struct scmi_smc *scmi_info) 66{ 67 if (IS_ENABLED(CONFIG_ARM_SCMI_TRANSPORT_SMC_ATOMIC_ENABLE)) 68 atomic_set(&scmi_info->inflight, INFLIGHT_NONE); 69 else 70 mutex_init(&scmi_info->shmem_lock); 71} 72 73static bool smc_xfer_inflight(struct scmi_xfer *xfer, atomic_t *inflight) 74{ 75 int ret; 76 77 ret = atomic_cmpxchg(inflight, INFLIGHT_NONE, xfer->hdr.seq); 78 79 return ret == INFLIGHT_NONE; 80} 81 82static inline void 83smc_channel_lock_acquire(struct scmi_smc *scmi_info, 84 struct scmi_xfer *xfer __maybe_unused) 85{ 86 if (IS_ENABLED(CONFIG_ARM_SCMI_TRANSPORT_SMC_ATOMIC_ENABLE)) 87 spin_until_cond(smc_xfer_inflight(xfer, &scmi_info->inflight)); 88 else 89 mutex_lock(&scmi_info->shmem_lock); 90} 91 92static inline void smc_channel_lock_release(struct scmi_smc *scmi_info) 93{ 94 if (IS_ENABLED(CONFIG_ARM_SCMI_TRANSPORT_SMC_ATOMIC_ENABLE)) 95 atomic_set(&scmi_info->inflight, INFLIGHT_NONE); 96 else 97 mutex_unlock(&scmi_info->shmem_lock); 98} 99 100static int smc_chan_setup(struct scmi_chan_info *cinfo, struct device *dev, 101 bool tx) 102{ 103 struct device *cdev = cinfo->dev; 104 struct scmi_smc *scmi_info; 105 resource_size_t size; 106 struct resource res; 107 struct device_node *np; 108 u32 func_id; 109 int ret, irq; 110 111 if (!tx) 112 return -ENODEV; 113 114 scmi_info = devm_kzalloc(dev, sizeof(*scmi_info), GFP_KERNEL); 115 if (!scmi_info) 116 return -ENOMEM; 117 118 np = of_parse_phandle(cdev->of_node, "shmem", 0); 119 if (!of_device_is_compatible(np, "arm,scmi-shmem")) 120 return -ENXIO; 121 122 ret = of_address_to_resource(np, 0, &res); 123 of_node_put(np); 124 if (ret) { 125 dev_err(cdev, "failed to get SCMI Tx shared memory\n"); 126 return ret; 127 } 128 129 size = resource_size(&res); 130 scmi_info->shmem = devm_ioremap(dev, res.start, size); 131 if (!scmi_info->shmem) { 132 dev_err(dev, "failed to ioremap SCMI Tx shared memory\n"); 133 return -EADDRNOTAVAIL; 134 } 135 136 ret = of_property_read_u32(dev->of_node, "arm,smc-id", &func_id); 137 if (ret < 0) 138 return ret; 139 140 /* 141 * If there is an interrupt named "a2p", then the service and 142 * completion of a message is signaled by an interrupt rather than by 143 * the return of the SMC call. 144 */ 145 irq = of_irq_get_byname(cdev->of_node, "a2p"); 146 if (irq > 0) { 147 ret = devm_request_irq(dev, irq, smc_msg_done_isr, 148 IRQF_NO_SUSPEND, 149 dev_name(dev), scmi_info); 150 if (ret) { 151 dev_err(dev, "failed to setup SCMI smc irq\n"); 152 return ret; 153 } 154 } else { 155 cinfo->no_completion_irq = true; 156 } 157 158 scmi_info->func_id = func_id; 159 scmi_info->cinfo = cinfo; 160 smc_channel_lock_init(scmi_info); 161 cinfo->transport_info = scmi_info; 162 163 return 0; 164} 165 166static int smc_chan_free(int id, void *p, void *data) 167{ 168 struct scmi_chan_info *cinfo = p; 169 struct scmi_smc *scmi_info = cinfo->transport_info; 170 171 cinfo->transport_info = NULL; 172 scmi_info->cinfo = NULL; 173 174 scmi_free_channel(cinfo, data, id); 175 176 return 0; 177} 178 179static int smc_send_message(struct scmi_chan_info *cinfo, 180 struct scmi_xfer *xfer) 181{ 182 struct scmi_smc *scmi_info = cinfo->transport_info; 183 struct arm_smccc_res res; 184 185 /* 186 * Channel will be released only once response has been 187 * surely fully retrieved, so after .mark_txdone() 188 */ 189 smc_channel_lock_acquire(scmi_info, xfer); 190 191 shmem_tx_prepare(scmi_info->shmem, xfer); 192 193 arm_smccc_1_1_invoke(scmi_info->func_id, 0, 0, 0, 0, 0, 0, 0, &res); 194 195 /* Only SMCCC_RET_NOT_SUPPORTED is valid error code */ 196 if (res.a0) { 197 smc_channel_lock_release(scmi_info); 198 return -EOPNOTSUPP; 199 } 200 201 return 0; 202} 203 204static void smc_fetch_response(struct scmi_chan_info *cinfo, 205 struct scmi_xfer *xfer) 206{ 207 struct scmi_smc *scmi_info = cinfo->transport_info; 208 209 shmem_fetch_response(scmi_info->shmem, xfer); 210} 211 212static void smc_mark_txdone(struct scmi_chan_info *cinfo, int ret, 213 struct scmi_xfer *__unused) 214{ 215 struct scmi_smc *scmi_info = cinfo->transport_info; 216 217 smc_channel_lock_release(scmi_info); 218} 219 220static const struct scmi_transport_ops scmi_smc_ops = { 221 .chan_available = smc_chan_available, 222 .chan_setup = smc_chan_setup, 223 .chan_free = smc_chan_free, 224 .send_message = smc_send_message, 225 .mark_txdone = smc_mark_txdone, 226 .fetch_response = smc_fetch_response, 227}; 228 229const struct scmi_desc scmi_smc_desc = { 230 .ops = &scmi_smc_ops, 231 .max_rx_timeout_ms = 30, 232 .max_msg = 20, 233 .max_msg_size = 128, 234 /* 235 * Setting .sync_cmds_atomic_replies to true for SMC assumes that, 236 * once the SMC instruction has completed successfully, the issued 237 * SCMI command would have been already fully processed by the SCMI 238 * platform firmware and so any possible response value expected 239 * for the issued command will be immmediately ready to be fetched 240 * from the shared memory area. 241 */ 242 .sync_cmds_completed_on_ret = true, 243 .atomic_enabled = IS_ENABLED(CONFIG_ARM_SCMI_TRANSPORT_SMC_ATOMIC_ENABLE), 244};