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 0x0 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 38 #define HICR6 0x4 39 #define HICR6_STR_SNP0W BIT(0) 40 #define HICR6_STR_SNP1W BIT(1) 41 #define SNPWADR 0x10 42 #define SNPWADR_CH0_MASK GENMASK(15, 0) 43 #define SNPWADR_CH0_SHIFT 0 44 #define SNPWADR_CH1_MASK GENMASK(31, 16) 45 #define SNPWADR_CH1_SHIFT 16 46 #define SNPWDR 0x14 47 #define SNPWDR_CH0_MASK GENMASK(7, 0) 48 #define SNPWDR_CH0_SHIFT 0 49 #define SNPWDR_CH1_MASK GENMASK(15, 8) 50 #define SNPWDR_CH1_SHIFT 8 51 #define HICRB 0x80 52 #define HICRB_ENSNP0D BIT(14) 53 #define HICRB_ENSNP1D BIT(15) 54 55 struct aspeed_lpc_snoop_model_data { 56 /* The ast2400 has bits 14 and 15 as reserved, whereas the ast2500 57 * can use them. 58 */ 59 unsigned int has_hicrb_ensnp; 60 }; 61 62 struct aspeed_lpc_snoop_channel { 63 struct kfifo fifo; 64 wait_queue_head_t wq; 65 struct miscdevice miscdev; 66 }; 67 68 struct aspeed_lpc_snoop { 69 struct regmap *regmap; 70 int irq; 71 struct clk *clk; 72 struct aspeed_lpc_snoop_channel chan[NUM_SNOOP_CHANNELS]; 73 }; 74 75 static struct aspeed_lpc_snoop_channel *snoop_file_to_chan(struct file *file) 76 { 77 return container_of(file->private_data, 78 struct aspeed_lpc_snoop_channel, 79 miscdev); 80 } 81 82 static ssize_t snoop_file_read(struct file *file, char __user *buffer, 83 size_t count, loff_t *ppos) 84 { 85 struct aspeed_lpc_snoop_channel *chan = snoop_file_to_chan(file); 86 unsigned int copied; 87 int ret = 0; 88 89 if (kfifo_is_empty(&chan->fifo)) { 90 if (file->f_flags & O_NONBLOCK) 91 return -EAGAIN; 92 ret = wait_event_interruptible(chan->wq, 93 !kfifo_is_empty(&chan->fifo)); 94 if (ret == -ERESTARTSYS) 95 return -EINTR; 96 } 97 ret = kfifo_to_user(&chan->fifo, buffer, count, &copied); 98 99 return ret ? ret : copied; 100 } 101 102 static __poll_t snoop_file_poll(struct file *file, 103 struct poll_table_struct *pt) 104 { 105 struct aspeed_lpc_snoop_channel *chan = snoop_file_to_chan(file); 106 107 poll_wait(file, &chan->wq, pt); 108 return !kfifo_is_empty(&chan->fifo) ? EPOLLIN : 0; 109 } 110 111 static const struct file_operations snoop_fops = { 112 .owner = THIS_MODULE, 113 .read = snoop_file_read, 114 .poll = snoop_file_poll, 115 .llseek = noop_llseek, 116 }; 117 118 /* Save a byte to a FIFO and discard the oldest byte if FIFO is full */ 119 static void put_fifo_with_discard(struct aspeed_lpc_snoop_channel *chan, u8 val) 120 { 121 if (!kfifo_initialized(&chan->fifo)) 122 return; 123 if (kfifo_is_full(&chan->fifo)) 124 kfifo_skip(&chan->fifo); 125 kfifo_put(&chan->fifo, val); 126 wake_up_interruptible(&chan->wq); 127 } 128 129 static irqreturn_t aspeed_lpc_snoop_irq(int irq, void *arg) 130 { 131 struct aspeed_lpc_snoop *lpc_snoop = arg; 132 u32 reg, data; 133 134 if (regmap_read(lpc_snoop->regmap, HICR6, ®)) 135 return IRQ_NONE; 136 137 /* Check if one of the snoop channels is interrupting */ 138 reg &= (HICR6_STR_SNP0W | HICR6_STR_SNP1W); 139 if (!reg) 140 return IRQ_NONE; 141 142 /* Ack pending IRQs */ 143 regmap_write(lpc_snoop->regmap, HICR6, reg); 144 145 /* Read and save most recent snoop'ed data byte to FIFO */ 146 regmap_read(lpc_snoop->regmap, SNPWDR, &data); 147 148 if (reg & HICR6_STR_SNP0W) { 149 u8 val = (data & SNPWDR_CH0_MASK) >> SNPWDR_CH0_SHIFT; 150 151 put_fifo_with_discard(&lpc_snoop->chan[0], val); 152 } 153 if (reg & HICR6_STR_SNP1W) { 154 u8 val = (data & SNPWDR_CH1_MASK) >> SNPWDR_CH1_SHIFT; 155 156 put_fifo_with_discard(&lpc_snoop->chan[1], val); 157 } 158 159 return IRQ_HANDLED; 160 } 161 162 static int aspeed_lpc_snoop_config_irq(struct aspeed_lpc_snoop *lpc_snoop, 163 struct platform_device *pdev) 164 { 165 struct device *dev = &pdev->dev; 166 int rc; 167 168 lpc_snoop->irq = platform_get_irq(pdev, 0); 169 if (!lpc_snoop->irq) 170 return -ENODEV; 171 172 rc = devm_request_irq(dev, lpc_snoop->irq, 173 aspeed_lpc_snoop_irq, IRQF_SHARED, 174 DEVICE_NAME, lpc_snoop); 175 if (rc < 0) { 176 dev_warn(dev, "Unable to request IRQ %d\n", lpc_snoop->irq); 177 lpc_snoop->irq = 0; 178 return rc; 179 } 180 181 return 0; 182 } 183 184 static int aspeed_lpc_enable_snoop(struct aspeed_lpc_snoop *lpc_snoop, 185 struct device *dev, 186 int channel, u16 lpc_port) 187 { 188 int rc = 0; 189 u32 hicr5_en, snpwadr_mask, snpwadr_shift, hicrb_en; 190 const struct aspeed_lpc_snoop_model_data *model_data = 191 of_device_get_match_data(dev); 192 193 init_waitqueue_head(&lpc_snoop->chan[channel].wq); 194 /* Create FIFO datastructure */ 195 rc = kfifo_alloc(&lpc_snoop->chan[channel].fifo, 196 SNOOP_FIFO_SIZE, GFP_KERNEL); 197 if (rc) 198 return rc; 199 200 lpc_snoop->chan[channel].miscdev.minor = MISC_DYNAMIC_MINOR; 201 lpc_snoop->chan[channel].miscdev.name = 202 devm_kasprintf(dev, GFP_KERNEL, "%s%d", DEVICE_NAME, channel); 203 lpc_snoop->chan[channel].miscdev.fops = &snoop_fops; 204 lpc_snoop->chan[channel].miscdev.parent = dev; 205 rc = misc_register(&lpc_snoop->chan[channel].miscdev); 206 if (rc) 207 return rc; 208 209 /* Enable LPC snoop channel at requested port */ 210 switch (channel) { 211 case 0: 212 hicr5_en = HICR5_EN_SNP0W | HICR5_ENINT_SNP0W; 213 snpwadr_mask = SNPWADR_CH0_MASK; 214 snpwadr_shift = SNPWADR_CH0_SHIFT; 215 hicrb_en = HICRB_ENSNP0D; 216 break; 217 case 1: 218 hicr5_en = HICR5_EN_SNP1W | HICR5_ENINT_SNP1W; 219 snpwadr_mask = SNPWADR_CH1_MASK; 220 snpwadr_shift = SNPWADR_CH1_SHIFT; 221 hicrb_en = HICRB_ENSNP1D; 222 break; 223 default: 224 return -EINVAL; 225 } 226 227 regmap_update_bits(lpc_snoop->regmap, HICR5, hicr5_en, hicr5_en); 228 regmap_update_bits(lpc_snoop->regmap, SNPWADR, snpwadr_mask, 229 lpc_port << snpwadr_shift); 230 if (model_data->has_hicrb_ensnp) 231 regmap_update_bits(lpc_snoop->regmap, HICRB, 232 hicrb_en, hicrb_en); 233 234 return rc; 235 } 236 237 static void aspeed_lpc_disable_snoop(struct aspeed_lpc_snoop *lpc_snoop, 238 int channel) 239 { 240 switch (channel) { 241 case 0: 242 regmap_update_bits(lpc_snoop->regmap, HICR5, 243 HICR5_EN_SNP0W | HICR5_ENINT_SNP0W, 244 0); 245 break; 246 case 1: 247 regmap_update_bits(lpc_snoop->regmap, HICR5, 248 HICR5_EN_SNP1W | HICR5_ENINT_SNP1W, 249 0); 250 break; 251 default: 252 return; 253 } 254 255 kfifo_free(&lpc_snoop->chan[channel].fifo); 256 misc_deregister(&lpc_snoop->chan[channel].miscdev); 257 } 258 259 static int aspeed_lpc_snoop_probe(struct platform_device *pdev) 260 { 261 struct aspeed_lpc_snoop *lpc_snoop; 262 struct device *dev; 263 u32 port; 264 int rc; 265 266 dev = &pdev->dev; 267 268 lpc_snoop = devm_kzalloc(dev, sizeof(*lpc_snoop), GFP_KERNEL); 269 if (!lpc_snoop) 270 return -ENOMEM; 271 272 lpc_snoop->regmap = syscon_node_to_regmap( 273 pdev->dev.parent->of_node); 274 if (IS_ERR(lpc_snoop->regmap)) { 275 dev_err(dev, "Couldn't get regmap\n"); 276 return -ENODEV; 277 } 278 279 dev_set_drvdata(&pdev->dev, lpc_snoop); 280 281 rc = of_property_read_u32_index(dev->of_node, "snoop-ports", 0, &port); 282 if (rc) { 283 dev_err(dev, "no snoop ports configured\n"); 284 return -ENODEV; 285 } 286 287 lpc_snoop->clk = devm_clk_get(dev, NULL); 288 if (IS_ERR(lpc_snoop->clk)) { 289 rc = PTR_ERR(lpc_snoop->clk); 290 if (rc != -EPROBE_DEFER) 291 dev_err(dev, "couldn't get clock\n"); 292 return rc; 293 } 294 rc = clk_prepare_enable(lpc_snoop->clk); 295 if (rc) { 296 dev_err(dev, "couldn't enable clock\n"); 297 return rc; 298 } 299 300 rc = aspeed_lpc_snoop_config_irq(lpc_snoop, pdev); 301 if (rc) 302 goto err; 303 304 rc = aspeed_lpc_enable_snoop(lpc_snoop, dev, 0, port); 305 if (rc) 306 goto err; 307 308 /* Configuration of 2nd snoop channel port is optional */ 309 if (of_property_read_u32_index(dev->of_node, "snoop-ports", 310 1, &port) == 0) { 311 rc = aspeed_lpc_enable_snoop(lpc_snoop, dev, 1, port); 312 if (rc) { 313 aspeed_lpc_disable_snoop(lpc_snoop, 0); 314 goto err; 315 } 316 } 317 318 return 0; 319 320 err: 321 clk_disable_unprepare(lpc_snoop->clk); 322 323 return rc; 324 } 325 326 static int aspeed_lpc_snoop_remove(struct platform_device *pdev) 327 { 328 struct aspeed_lpc_snoop *lpc_snoop = dev_get_drvdata(&pdev->dev); 329 330 /* Disable both snoop channels */ 331 aspeed_lpc_disable_snoop(lpc_snoop, 0); 332 aspeed_lpc_disable_snoop(lpc_snoop, 1); 333 334 clk_disable_unprepare(lpc_snoop->clk); 335 336 return 0; 337 } 338 339 static const struct aspeed_lpc_snoop_model_data ast2400_model_data = { 340 .has_hicrb_ensnp = 0, 341 }; 342 343 static const struct aspeed_lpc_snoop_model_data ast2500_model_data = { 344 .has_hicrb_ensnp = 1, 345 }; 346 347 static const struct of_device_id aspeed_lpc_snoop_match[] = { 348 { .compatible = "aspeed,ast2400-lpc-snoop", 349 .data = &ast2400_model_data }, 350 { .compatible = "aspeed,ast2500-lpc-snoop", 351 .data = &ast2500_model_data }, 352 { .compatible = "aspeed,ast2600-lpc-snoop", 353 .data = &ast2500_model_data }, 354 { }, 355 }; 356 357 static struct platform_driver aspeed_lpc_snoop_driver = { 358 .driver = { 359 .name = DEVICE_NAME, 360 .of_match_table = aspeed_lpc_snoop_match, 361 }, 362 .probe = aspeed_lpc_snoop_probe, 363 .remove = aspeed_lpc_snoop_remove, 364 }; 365 366 module_platform_driver(aspeed_lpc_snoop_driver); 367 368 MODULE_DEVICE_TABLE(of, aspeed_lpc_snoop_match); 369 MODULE_LICENSE("GPL"); 370 MODULE_AUTHOR("Robert Lippert <rlippert@google.com>"); 371 MODULE_DESCRIPTION("Linux driver to control Aspeed LPC snoop functionality"); 372