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/interrupt.h> 15 #include <linux/fs.h> 16 #include <linux/kfifo.h> 17 #include <linux/mfd/syscon.h> 18 #include <linux/miscdevice.h> 19 #include <linux/module.h> 20 #include <linux/of.h> 21 #include <linux/of_device.h> 22 #include <linux/platform_device.h> 23 #include <linux/poll.h> 24 #include <linux/regmap.h> 25 26 #define DEVICE_NAME "aspeed-lpc-snoop" 27 28 #define NUM_SNOOP_CHANNELS 2 29 #define SNOOP_FIFO_SIZE 2048 30 31 #define HICR5 0x0 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 37 #define HICR6 0x4 38 #define HICR6_STR_SNP0W BIT(0) 39 #define HICR6_STR_SNP1W BIT(1) 40 #define SNPWADR 0x10 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 0x14 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 0x80 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 aspeed_lpc_snoop_channel chan[NUM_SNOOP_CHANNELS]; 71 }; 72 73 static struct aspeed_lpc_snoop_channel *snoop_file_to_chan(struct file *file) 74 { 75 return container_of(file->private_data, 76 struct aspeed_lpc_snoop_channel, 77 miscdev); 78 } 79 80 static ssize_t snoop_file_read(struct file *file, char __user *buffer, 81 size_t count, loff_t *ppos) 82 { 83 struct aspeed_lpc_snoop_channel *chan = snoop_file_to_chan(file); 84 unsigned int copied; 85 int ret = 0; 86 87 if (kfifo_is_empty(&chan->fifo)) { 88 if (file->f_flags & O_NONBLOCK) 89 return -EAGAIN; 90 ret = wait_event_interruptible(chan->wq, 91 !kfifo_is_empty(&chan->fifo)); 92 if (ret == -ERESTARTSYS) 93 return -EINTR; 94 } 95 ret = kfifo_to_user(&chan->fifo, buffer, count, &copied); 96 97 return ret ? ret : copied; 98 } 99 100 static __poll_t snoop_file_poll(struct file *file, 101 struct poll_table_struct *pt) 102 { 103 struct aspeed_lpc_snoop_channel *chan = snoop_file_to_chan(file); 104 105 poll_wait(file, &chan->wq, pt); 106 return !kfifo_is_empty(&chan->fifo) ? EPOLLIN : 0; 107 } 108 109 static const struct file_operations snoop_fops = { 110 .owner = THIS_MODULE, 111 .read = snoop_file_read, 112 .poll = snoop_file_poll, 113 .llseek = noop_llseek, 114 }; 115 116 /* Save a byte to a FIFO and discard the oldest byte if FIFO is full */ 117 static void put_fifo_with_discard(struct aspeed_lpc_snoop_channel *chan, u8 val) 118 { 119 if (!kfifo_initialized(&chan->fifo)) 120 return; 121 if (kfifo_is_full(&chan->fifo)) 122 kfifo_skip(&chan->fifo); 123 kfifo_put(&chan->fifo, val); 124 wake_up_interruptible(&chan->wq); 125 } 126 127 static irqreturn_t aspeed_lpc_snoop_irq(int irq, void *arg) 128 { 129 struct aspeed_lpc_snoop *lpc_snoop = arg; 130 u32 reg, data; 131 132 if (regmap_read(lpc_snoop->regmap, HICR6, ®)) 133 return IRQ_NONE; 134 135 /* Check if one of the snoop channels is interrupting */ 136 reg &= (HICR6_STR_SNP0W | HICR6_STR_SNP1W); 137 if (!reg) 138 return IRQ_NONE; 139 140 /* Ack pending IRQs */ 141 regmap_write(lpc_snoop->regmap, HICR6, reg); 142 143 /* Read and save most recent snoop'ed data byte to FIFO */ 144 regmap_read(lpc_snoop->regmap, SNPWDR, &data); 145 146 if (reg & HICR6_STR_SNP0W) { 147 u8 val = (data & SNPWDR_CH0_MASK) >> SNPWDR_CH0_SHIFT; 148 149 put_fifo_with_discard(&lpc_snoop->chan[0], val); 150 } 151 if (reg & HICR6_STR_SNP1W) { 152 u8 val = (data & SNPWDR_CH1_MASK) >> SNPWDR_CH1_SHIFT; 153 154 put_fifo_with_discard(&lpc_snoop->chan[1], val); 155 } 156 157 return IRQ_HANDLED; 158 } 159 160 static int aspeed_lpc_snoop_config_irq(struct aspeed_lpc_snoop *lpc_snoop, 161 struct platform_device *pdev) 162 { 163 struct device *dev = &pdev->dev; 164 int rc; 165 166 lpc_snoop->irq = platform_get_irq(pdev, 0); 167 if (!lpc_snoop->irq) 168 return -ENODEV; 169 170 rc = devm_request_irq(dev, lpc_snoop->irq, 171 aspeed_lpc_snoop_irq, IRQF_SHARED, 172 DEVICE_NAME, lpc_snoop); 173 if (rc < 0) { 174 dev_warn(dev, "Unable to request IRQ %d\n", lpc_snoop->irq); 175 lpc_snoop->irq = 0; 176 return rc; 177 } 178 179 return 0; 180 } 181 182 static int aspeed_lpc_enable_snoop(struct aspeed_lpc_snoop *lpc_snoop, 183 struct device *dev, 184 int channel, u16 lpc_port) 185 { 186 int rc = 0; 187 u32 hicr5_en, snpwadr_mask, snpwadr_shift, hicrb_en; 188 const struct aspeed_lpc_snoop_model_data *model_data = 189 of_device_get_match_data(dev); 190 191 init_waitqueue_head(&lpc_snoop->chan[channel].wq); 192 /* Create FIFO datastructure */ 193 rc = kfifo_alloc(&lpc_snoop->chan[channel].fifo, 194 SNOOP_FIFO_SIZE, GFP_KERNEL); 195 if (rc) 196 return rc; 197 198 lpc_snoop->chan[channel].miscdev.minor = MISC_DYNAMIC_MINOR; 199 lpc_snoop->chan[channel].miscdev.name = 200 devm_kasprintf(dev, GFP_KERNEL, "%s%d", DEVICE_NAME, channel); 201 lpc_snoop->chan[channel].miscdev.fops = &snoop_fops; 202 lpc_snoop->chan[channel].miscdev.parent = dev; 203 rc = misc_register(&lpc_snoop->chan[channel].miscdev); 204 if (rc) 205 return rc; 206 207 /* Enable LPC snoop channel at requested port */ 208 switch (channel) { 209 case 0: 210 hicr5_en = HICR5_EN_SNP0W | HICR5_ENINT_SNP0W; 211 snpwadr_mask = SNPWADR_CH0_MASK; 212 snpwadr_shift = SNPWADR_CH0_SHIFT; 213 hicrb_en = HICRB_ENSNP0D; 214 break; 215 case 1: 216 hicr5_en = HICR5_EN_SNP1W | HICR5_ENINT_SNP1W; 217 snpwadr_mask = SNPWADR_CH1_MASK; 218 snpwadr_shift = SNPWADR_CH1_SHIFT; 219 hicrb_en = HICRB_ENSNP1D; 220 break; 221 default: 222 return -EINVAL; 223 } 224 225 regmap_update_bits(lpc_snoop->regmap, HICR5, hicr5_en, hicr5_en); 226 regmap_update_bits(lpc_snoop->regmap, SNPWADR, snpwadr_mask, 227 lpc_port << snpwadr_shift); 228 if (model_data->has_hicrb_ensnp) 229 regmap_update_bits(lpc_snoop->regmap, HICRB, 230 hicrb_en, hicrb_en); 231 232 return rc; 233 } 234 235 static void aspeed_lpc_disable_snoop(struct aspeed_lpc_snoop *lpc_snoop, 236 int channel) 237 { 238 switch (channel) { 239 case 0: 240 regmap_update_bits(lpc_snoop->regmap, HICR5, 241 HICR5_EN_SNP0W | HICR5_ENINT_SNP0W, 242 0); 243 break; 244 case 1: 245 regmap_update_bits(lpc_snoop->regmap, HICR5, 246 HICR5_EN_SNP1W | HICR5_ENINT_SNP1W, 247 0); 248 break; 249 default: 250 return; 251 } 252 253 kfifo_free(&lpc_snoop->chan[channel].fifo); 254 misc_deregister(&lpc_snoop->chan[channel].miscdev); 255 } 256 257 static int aspeed_lpc_snoop_probe(struct platform_device *pdev) 258 { 259 struct aspeed_lpc_snoop *lpc_snoop; 260 struct device *dev; 261 u32 port; 262 int rc; 263 264 dev = &pdev->dev; 265 266 lpc_snoop = devm_kzalloc(dev, sizeof(*lpc_snoop), GFP_KERNEL); 267 if (!lpc_snoop) 268 return -ENOMEM; 269 270 lpc_snoop->regmap = syscon_node_to_regmap( 271 pdev->dev.parent->of_node); 272 if (IS_ERR(lpc_snoop->regmap)) { 273 dev_err(dev, "Couldn't get regmap\n"); 274 return -ENODEV; 275 } 276 277 dev_set_drvdata(&pdev->dev, lpc_snoop); 278 279 rc = of_property_read_u32_index(dev->of_node, "snoop-ports", 0, &port); 280 if (rc) { 281 dev_err(dev, "no snoop ports configured\n"); 282 return -ENODEV; 283 } 284 285 rc = aspeed_lpc_snoop_config_irq(lpc_snoop, pdev); 286 if (rc) 287 return rc; 288 289 rc = aspeed_lpc_enable_snoop(lpc_snoop, dev, 0, port); 290 if (rc) 291 return rc; 292 293 /* Configuration of 2nd snoop channel port is optional */ 294 if (of_property_read_u32_index(dev->of_node, "snoop-ports", 295 1, &port) == 0) { 296 rc = aspeed_lpc_enable_snoop(lpc_snoop, dev, 1, port); 297 if (rc) 298 aspeed_lpc_disable_snoop(lpc_snoop, 0); 299 } 300 301 return rc; 302 } 303 304 static int aspeed_lpc_snoop_remove(struct platform_device *pdev) 305 { 306 struct aspeed_lpc_snoop *lpc_snoop = dev_get_drvdata(&pdev->dev); 307 308 /* Disable both snoop channels */ 309 aspeed_lpc_disable_snoop(lpc_snoop, 0); 310 aspeed_lpc_disable_snoop(lpc_snoop, 1); 311 312 return 0; 313 } 314 315 static const struct aspeed_lpc_snoop_model_data ast2400_model_data = { 316 .has_hicrb_ensnp = 0, 317 }; 318 319 static const struct aspeed_lpc_snoop_model_data ast2500_model_data = { 320 .has_hicrb_ensnp = 1, 321 }; 322 323 static const struct of_device_id aspeed_lpc_snoop_match[] = { 324 { .compatible = "aspeed,ast2400-lpc-snoop", 325 .data = &ast2400_model_data }, 326 { .compatible = "aspeed,ast2500-lpc-snoop", 327 .data = &ast2500_model_data }, 328 { }, 329 }; 330 331 static struct platform_driver aspeed_lpc_snoop_driver = { 332 .driver = { 333 .name = DEVICE_NAME, 334 .of_match_table = aspeed_lpc_snoop_match, 335 }, 336 .probe = aspeed_lpc_snoop_probe, 337 .remove = aspeed_lpc_snoop_remove, 338 }; 339 340 module_platform_driver(aspeed_lpc_snoop_driver); 341 342 MODULE_DEVICE_TABLE(of, aspeed_lpc_snoop_match); 343 MODULE_LICENSE("GPL"); 344 MODULE_AUTHOR("Robert Lippert <rlippert@google.com>"); 345 MODULE_DESCRIPTION("Linux driver to control Aspeed LPC snoop functionality"); 346