1 // SPDX-License-Identifier: GPL-2.0-or-later 2 /* 3 * Copyright 2017 Google Inc 4 * 5 * Provides a simple driver to control the ASPEED LPC snoop interface which 6 * allows the BMC to listen on and save the data written by 7 * the host to an arbitrary LPC I/O port. 8 * 9 * Typically used by the BMC to "watch" host boot progress via port 10 * 0x80 writes made by the BIOS during the boot process. 11 */ 12 13 #include <linux/bitops.h> 14 #include <linux/clk.h> 15 #include <linux/dev_printk.h> 16 #include <linux/interrupt.h> 17 #include <linux/fs.h> 18 #include <linux/kfifo.h> 19 #include <linux/mfd/syscon.h> 20 #include <linux/miscdevice.h> 21 #include <linux/module.h> 22 #include <linux/of.h> 23 #include <linux/platform_device.h> 24 #include <linux/poll.h> 25 #include <linux/regmap.h> 26 27 #define DEVICE_NAME "aspeed-lpc-snoop" 28 29 #define SNOOP_FIFO_SIZE 2048 30 31 #define HICR5 0x80 32 #define HICR5_EN_SNP0W BIT(0) 33 #define HICR5_ENINT_SNP0W BIT(1) 34 #define HICR5_EN_SNP1W BIT(2) 35 #define HICR5_ENINT_SNP1W BIT(3) 36 #define HICR6 0x84 37 #define HICR6_STR_SNP0W BIT(0) 38 #define HICR6_STR_SNP1W BIT(1) 39 #define SNPWADR 0x90 40 #define SNPWADR_CH0_MASK GENMASK(15, 0) 41 #define SNPWADR_CH0_SHIFT 0 42 #define SNPWADR_CH1_MASK GENMASK(31, 16) 43 #define SNPWADR_CH1_SHIFT 16 44 #define SNPWDR 0x94 45 #define SNPWDR_CH0_MASK GENMASK(7, 0) 46 #define SNPWDR_CH0_SHIFT 0 47 #define SNPWDR_CH1_MASK GENMASK(15, 8) 48 #define SNPWDR_CH1_SHIFT 8 49 #define HICRB 0x100 50 #define HICRB_ENSNP0D BIT(14) 51 #define HICRB_ENSNP1D BIT(15) 52 53 struct aspeed_lpc_snoop_model_data { 54 /* The ast2400 has bits 14 and 15 as reserved, whereas the ast2500 55 * can use them. 56 */ 57 unsigned int has_hicrb_ensnp; 58 }; 59 60 enum aspeed_lpc_snoop_index { 61 ASPEED_LPC_SNOOP_INDEX_0 = 0, 62 ASPEED_LPC_SNOOP_INDEX_1 = 1, 63 ASPEED_LPC_SNOOP_INDEX_MAX = ASPEED_LPC_SNOOP_INDEX_1, 64 }; 65 66 struct aspeed_lpc_snoop_channel_cfg { 67 enum aspeed_lpc_snoop_index index; 68 u32 hicr5_en; 69 u32 snpwadr_mask; 70 u32 snpwadr_shift; 71 u32 hicrb_en; 72 }; 73 74 struct aspeed_lpc_snoop_channel { 75 const struct aspeed_lpc_snoop_channel_cfg *cfg; 76 bool enabled; 77 struct kfifo fifo; 78 wait_queue_head_t wq; 79 struct miscdevice miscdev; 80 }; 81 82 struct aspeed_lpc_snoop { 83 struct regmap *regmap; 84 int irq; 85 struct clk *clk; 86 struct aspeed_lpc_snoop_channel chan[ASPEED_LPC_SNOOP_INDEX_MAX + 1]; 87 }; 88 89 static const struct aspeed_lpc_snoop_channel_cfg channel_cfgs[ASPEED_LPC_SNOOP_INDEX_MAX + 1] = { 90 { 91 .index = ASPEED_LPC_SNOOP_INDEX_0, 92 .hicr5_en = HICR5_EN_SNP0W | HICR5_ENINT_SNP0W, 93 .snpwadr_mask = SNPWADR_CH0_MASK, 94 .snpwadr_shift = SNPWADR_CH0_SHIFT, 95 .hicrb_en = HICRB_ENSNP0D, 96 }, 97 { 98 .index = ASPEED_LPC_SNOOP_INDEX_1, 99 .hicr5_en = HICR5_EN_SNP1W | HICR5_ENINT_SNP1W, 100 .snpwadr_mask = SNPWADR_CH1_MASK, 101 .snpwadr_shift = SNPWADR_CH1_SHIFT, 102 .hicrb_en = HICRB_ENSNP1D, 103 }, 104 }; 105 106 static struct aspeed_lpc_snoop_channel *snoop_file_to_chan(struct file *file) 107 { 108 return container_of(file->private_data, 109 struct aspeed_lpc_snoop_channel, 110 miscdev); 111 } 112 113 static ssize_t snoop_file_read(struct file *file, char __user *buffer, 114 size_t count, loff_t *ppos) 115 { 116 struct aspeed_lpc_snoop_channel *chan = snoop_file_to_chan(file); 117 unsigned int copied; 118 int ret = 0; 119 120 if (kfifo_is_empty(&chan->fifo)) { 121 if (file->f_flags & O_NONBLOCK) 122 return -EAGAIN; 123 ret = wait_event_interruptible(chan->wq, 124 !kfifo_is_empty(&chan->fifo)); 125 if (ret == -ERESTARTSYS) 126 return -EINTR; 127 } 128 ret = kfifo_to_user(&chan->fifo, buffer, count, &copied); 129 if (ret) 130 return ret; 131 132 return copied; 133 } 134 135 static __poll_t snoop_file_poll(struct file *file, 136 struct poll_table_struct *pt) 137 { 138 struct aspeed_lpc_snoop_channel *chan = snoop_file_to_chan(file); 139 140 poll_wait(file, &chan->wq, pt); 141 return !kfifo_is_empty(&chan->fifo) ? EPOLLIN : 0; 142 } 143 144 static const struct file_operations snoop_fops = { 145 .owner = THIS_MODULE, 146 .read = snoop_file_read, 147 .poll = snoop_file_poll, 148 .llseek = noop_llseek, 149 }; 150 151 /* Save a byte to a FIFO and discard the oldest byte if FIFO is full */ 152 static void put_fifo_with_discard(struct aspeed_lpc_snoop_channel *chan, u8 val) 153 { 154 if (!kfifo_initialized(&chan->fifo)) 155 return; 156 if (kfifo_is_full(&chan->fifo)) 157 kfifo_skip(&chan->fifo); 158 kfifo_put(&chan->fifo, val); 159 wake_up_interruptible(&chan->wq); 160 } 161 162 static irqreturn_t aspeed_lpc_snoop_irq(int irq, void *arg) 163 { 164 struct aspeed_lpc_snoop *lpc_snoop = arg; 165 u32 reg, data; 166 167 if (regmap_read(lpc_snoop->regmap, HICR6, ®)) 168 return IRQ_NONE; 169 170 /* Check if one of the snoop channels is interrupting */ 171 reg &= (HICR6_STR_SNP0W | HICR6_STR_SNP1W); 172 if (!reg) 173 return IRQ_NONE; 174 175 /* Ack pending IRQs */ 176 regmap_write(lpc_snoop->regmap, HICR6, reg); 177 178 /* Read and save most recent snoop'ed data byte to FIFO */ 179 regmap_read(lpc_snoop->regmap, SNPWDR, &data); 180 181 if (reg & HICR6_STR_SNP0W) { 182 u8 val = (data & SNPWDR_CH0_MASK) >> SNPWDR_CH0_SHIFT; 183 184 put_fifo_with_discard(&lpc_snoop->chan[0], val); 185 } 186 if (reg & HICR6_STR_SNP1W) { 187 u8 val = (data & SNPWDR_CH1_MASK) >> SNPWDR_CH1_SHIFT; 188 189 put_fifo_with_discard(&lpc_snoop->chan[1], val); 190 } 191 192 return IRQ_HANDLED; 193 } 194 195 static int aspeed_lpc_snoop_config_irq(struct aspeed_lpc_snoop *lpc_snoop, 196 struct platform_device *pdev) 197 { 198 struct device *dev = &pdev->dev; 199 int rc; 200 201 lpc_snoop->irq = platform_get_irq(pdev, 0); 202 if (lpc_snoop->irq < 0) 203 return -ENODEV; 204 205 rc = devm_request_irq(dev, lpc_snoop->irq, 206 aspeed_lpc_snoop_irq, IRQF_SHARED, 207 DEVICE_NAME, lpc_snoop); 208 if (rc < 0) { 209 dev_warn(dev, "Unable to request IRQ %d\n", lpc_snoop->irq); 210 lpc_snoop->irq = 0; 211 return rc; 212 } 213 214 return 0; 215 } 216 217 __attribute__((nonnull)) 218 static int aspeed_lpc_enable_snoop(struct device *dev, 219 struct aspeed_lpc_snoop *lpc_snoop, 220 struct aspeed_lpc_snoop_channel *channel, 221 const struct aspeed_lpc_snoop_channel_cfg *cfg, 222 u16 lpc_port) 223 { 224 const struct aspeed_lpc_snoop_model_data *model_data; 225 int rc = 0; 226 227 if (WARN_ON(channel->enabled)) 228 return -EBUSY; 229 230 init_waitqueue_head(&channel->wq); 231 232 channel->cfg = cfg; 233 channel->miscdev.minor = MISC_DYNAMIC_MINOR; 234 channel->miscdev.fops = &snoop_fops; 235 channel->miscdev.parent = dev; 236 237 channel->miscdev.name = 238 devm_kasprintf(dev, GFP_KERNEL, "%s%d", DEVICE_NAME, cfg->index); 239 if (!channel->miscdev.name) 240 return -ENOMEM; 241 242 rc = kfifo_alloc(&channel->fifo, SNOOP_FIFO_SIZE, GFP_KERNEL); 243 if (rc) 244 return rc; 245 246 rc = misc_register(&channel->miscdev); 247 if (rc) 248 goto err_free_fifo; 249 250 /* Enable LPC snoop channel at requested port */ 251 regmap_set_bits(lpc_snoop->regmap, HICR5, cfg->hicr5_en); 252 regmap_update_bits(lpc_snoop->regmap, SNPWADR, cfg->snpwadr_mask, 253 lpc_port << cfg->snpwadr_shift); 254 255 model_data = of_device_get_match_data(dev); 256 if (model_data && model_data->has_hicrb_ensnp) 257 regmap_set_bits(lpc_snoop->regmap, HICRB, cfg->hicrb_en); 258 259 channel->enabled = true; 260 261 return 0; 262 263 err_free_fifo: 264 kfifo_free(&channel->fifo); 265 return rc; 266 } 267 268 __attribute__((nonnull)) 269 static void aspeed_lpc_disable_snoop(struct aspeed_lpc_snoop *lpc_snoop, 270 struct aspeed_lpc_snoop_channel *channel) 271 { 272 if (!channel->enabled) 273 return; 274 275 /* Disable interrupts along with the device */ 276 regmap_clear_bits(lpc_snoop->regmap, HICR5, channel->cfg->hicr5_en); 277 278 channel->enabled = false; 279 /* Consider improving safety wrt concurrent reader(s) */ 280 misc_deregister(&channel->miscdev); 281 kfifo_free(&channel->fifo); 282 } 283 284 static void aspeed_lpc_snoop_remove(struct platform_device *pdev) 285 { 286 struct aspeed_lpc_snoop *lpc_snoop = dev_get_drvdata(&pdev->dev); 287 288 /* Disable both snoop channels */ 289 aspeed_lpc_disable_snoop(lpc_snoop, &lpc_snoop->chan[0]); 290 aspeed_lpc_disable_snoop(lpc_snoop, &lpc_snoop->chan[1]); 291 } 292 293 static int aspeed_lpc_snoop_probe(struct platform_device *pdev) 294 { 295 struct aspeed_lpc_snoop *lpc_snoop; 296 struct device_node *np; 297 struct device *dev; 298 int idx; 299 int rc; 300 301 dev = &pdev->dev; 302 303 lpc_snoop = devm_kzalloc(dev, sizeof(*lpc_snoop), GFP_KERNEL); 304 if (!lpc_snoop) 305 return -ENOMEM; 306 307 np = pdev->dev.parent->of_node; 308 if (!of_device_is_compatible(np, "aspeed,ast2400-lpc-v2") && 309 !of_device_is_compatible(np, "aspeed,ast2500-lpc-v2") && 310 !of_device_is_compatible(np, "aspeed,ast2600-lpc-v2")) { 311 dev_err(dev, "unsupported LPC device binding\n"); 312 return -ENODEV; 313 } 314 315 lpc_snoop->regmap = syscon_node_to_regmap(np); 316 if (IS_ERR(lpc_snoop->regmap)) 317 return dev_err_probe(dev, PTR_ERR(lpc_snoop->regmap), "Couldn't get regmap\n"); 318 319 dev_set_drvdata(&pdev->dev, lpc_snoop); 320 321 lpc_snoop->clk = devm_clk_get_enabled(dev, NULL); 322 if (IS_ERR(lpc_snoop->clk)) 323 return dev_err_probe(dev, PTR_ERR(lpc_snoop->clk), "couldn't get clock"); 324 325 rc = aspeed_lpc_snoop_config_irq(lpc_snoop, pdev); 326 if (rc) 327 return rc; 328 329 static_assert(ARRAY_SIZE(channel_cfgs) == ARRAY_SIZE(lpc_snoop->chan), 330 "Broken implementation assumption regarding cfg count"); 331 for (idx = ASPEED_LPC_SNOOP_INDEX_0; idx <= ASPEED_LPC_SNOOP_INDEX_MAX; idx++) { 332 u32 port; 333 334 rc = of_property_read_u32_index(dev->of_node, "snoop-ports", idx, &port); 335 if (rc) 336 break; 337 338 rc = aspeed_lpc_enable_snoop(dev, lpc_snoop, &lpc_snoop->chan[idx], 339 &channel_cfgs[idx], port); 340 if (rc) 341 goto cleanup_channels; 342 } 343 344 return idx == ASPEED_LPC_SNOOP_INDEX_0 ? -ENODEV : 0; 345 346 cleanup_channels: 347 aspeed_lpc_snoop_remove(pdev); 348 349 return rc; 350 } 351 352 static const struct aspeed_lpc_snoop_model_data ast2400_model_data = { 353 .has_hicrb_ensnp = 0, 354 }; 355 356 static const struct aspeed_lpc_snoop_model_data ast2500_model_data = { 357 .has_hicrb_ensnp = 1, 358 }; 359 360 static const struct of_device_id aspeed_lpc_snoop_match[] = { 361 { .compatible = "aspeed,ast2400-lpc-snoop", 362 .data = &ast2400_model_data }, 363 { .compatible = "aspeed,ast2500-lpc-snoop", 364 .data = &ast2500_model_data }, 365 { .compatible = "aspeed,ast2600-lpc-snoop", 366 .data = &ast2500_model_data }, 367 { }, 368 }; 369 370 static struct platform_driver aspeed_lpc_snoop_driver = { 371 .driver = { 372 .name = DEVICE_NAME, 373 .of_match_table = aspeed_lpc_snoop_match, 374 }, 375 .probe = aspeed_lpc_snoop_probe, 376 .remove = aspeed_lpc_snoop_remove, 377 }; 378 379 module_platform_driver(aspeed_lpc_snoop_driver); 380 381 MODULE_DEVICE_TABLE(of, aspeed_lpc_snoop_match); 382 MODULE_LICENSE("GPL"); 383 MODULE_AUTHOR("Robert Lippert <rlippert@google.com>"); 384 MODULE_DESCRIPTION("Linux driver to control Aspeed LPC snoop functionality"); 385