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