1 // SPDX-License-Identifier: GPL-2.0-only 2 /* 3 * Copyright (C) 2020 BAIKAL ELECTRONICS, JSC 4 * 5 * Authors: 6 * Serge Semin <Sergey.Semin@baikalelectronics.ru> 7 * 8 * Baikal-T1 APB-bus driver 9 */ 10 11 #include <linux/kernel.h> 12 #include <linux/module.h> 13 #include <linux/types.h> 14 #include <linux/device.h> 15 #include <linux/atomic.h> 16 #include <linux/platform_device.h> 17 #include <linux/interrupt.h> 18 #include <linux/io.h> 19 #include <linux/nmi.h> 20 #include <linux/of.h> 21 #include <linux/regmap.h> 22 #include <linux/clk.h> 23 #include <linux/reset.h> 24 #include <linux/time64.h> 25 #include <linux/clk.h> 26 #include <linux/sysfs.h> 27 28 #define APB_EHB_ISR 0x00 29 #define APB_EHB_ISR_PENDING BIT(0) 30 #define APB_EHB_ISR_MASK BIT(1) 31 #define APB_EHB_ADDR 0x04 32 #define APB_EHB_TIMEOUT 0x08 33 34 #define APB_EHB_TIMEOUT_MIN 0x000003FFU 35 #define APB_EHB_TIMEOUT_MAX 0xFFFFFFFFU 36 37 /* 38 * struct bt1_apb - Baikal-T1 APB EHB private data 39 * @dev: Pointer to the device structure. 40 * @regs: APB EHB registers map. 41 * @res: No-device error injection memory region. 42 * @irq: Errors IRQ number. 43 * @rate: APB-bus reference clock rate. 44 * @pclk: APB-reference clock. 45 * @prst: APB domain reset line. 46 * @count: Number of errors detected. 47 */ 48 struct bt1_apb { 49 struct device *dev; 50 51 struct regmap *regs; 52 void __iomem *res; 53 int irq; 54 55 unsigned long rate; 56 struct clk *pclk; 57 58 struct reset_control *prst; 59 60 atomic_t count; 61 }; 62 63 static const struct regmap_config bt1_apb_regmap_cfg = { 64 .reg_bits = 32, 65 .val_bits = 32, 66 .reg_stride = 4, 67 .max_register = APB_EHB_TIMEOUT, 68 .fast_io = true 69 }; 70 71 static inline unsigned long bt1_apb_n_to_timeout_us(struct bt1_apb *apb, u32 n) 72 { 73 u64 timeout = (u64)n * USEC_PER_SEC; 74 75 do_div(timeout, apb->rate); 76 77 return timeout; 78 79 } 80 81 static inline unsigned long bt1_apb_timeout_to_n_us(struct bt1_apb *apb, 82 unsigned long timeout) 83 { 84 u64 n = (u64)timeout * apb->rate; 85 86 do_div(n, USEC_PER_SEC); 87 88 return n; 89 90 } 91 92 static irqreturn_t bt1_apb_isr(int irq, void *data) 93 { 94 struct bt1_apb *apb = data; 95 u32 addr = 0; 96 97 regmap_read(apb->regs, APB_EHB_ADDR, &addr); 98 99 dev_crit_ratelimited(apb->dev, 100 "APB-bus fault %d: Slave access timeout at 0x%08x\n", 101 atomic_inc_return(&apb->count), 102 addr); 103 104 /* 105 * Print backtrace on each CPU. This might be pointless if the fault 106 * has happened on the same CPU as the IRQ handler is executed or 107 * the other core proceeded further execution despite the error. 108 * But if it's not, by looking at the trace we would get straight to 109 * the cause of the problem. 110 */ 111 trigger_all_cpu_backtrace(); 112 113 regmap_update_bits(apb->regs, APB_EHB_ISR, APB_EHB_ISR_PENDING, 0); 114 115 return IRQ_HANDLED; 116 } 117 118 static void bt1_apb_clear_data(void *data) 119 { 120 struct bt1_apb *apb = data; 121 struct platform_device *pdev = to_platform_device(apb->dev); 122 123 platform_set_drvdata(pdev, NULL); 124 } 125 126 static struct bt1_apb *bt1_apb_create_data(struct platform_device *pdev) 127 { 128 struct device *dev = &pdev->dev; 129 struct bt1_apb *apb; 130 int ret; 131 132 apb = devm_kzalloc(dev, sizeof(*apb), GFP_KERNEL); 133 if (!apb) 134 return ERR_PTR(-ENOMEM); 135 136 ret = devm_add_action(dev, bt1_apb_clear_data, apb); 137 if (ret) { 138 dev_err(dev, "Can't add APB EHB data clear action\n"); 139 return ERR_PTR(ret); 140 } 141 142 apb->dev = dev; 143 atomic_set(&apb->count, 0); 144 platform_set_drvdata(pdev, apb); 145 146 return apb; 147 } 148 149 static int bt1_apb_request_regs(struct bt1_apb *apb) 150 { 151 struct platform_device *pdev = to_platform_device(apb->dev); 152 void __iomem *regs; 153 154 regs = devm_platform_ioremap_resource_byname(pdev, "ehb"); 155 if (IS_ERR(regs)) { 156 dev_err(apb->dev, "Couldn't map APB EHB registers\n"); 157 return PTR_ERR(regs); 158 } 159 160 apb->regs = devm_regmap_init_mmio(apb->dev, regs, &bt1_apb_regmap_cfg); 161 if (IS_ERR(apb->regs)) { 162 dev_err(apb->dev, "Couldn't create APB EHB regmap\n"); 163 return PTR_ERR(apb->regs); 164 } 165 166 apb->res = devm_platform_ioremap_resource_byname(pdev, "nodev"); 167 if (IS_ERR(apb->res)) { 168 dev_err(apb->dev, "Couldn't map reserved region\n"); 169 return PTR_ERR(apb->res); 170 } 171 172 return 0; 173 } 174 175 static int bt1_apb_request_rst(struct bt1_apb *apb) 176 { 177 int ret; 178 179 apb->prst = devm_reset_control_get_optional_exclusive(apb->dev, "prst"); 180 if (IS_ERR(apb->prst)) { 181 dev_warn(apb->dev, "Couldn't get reset control line\n"); 182 return PTR_ERR(apb->prst); 183 } 184 185 ret = reset_control_deassert(apb->prst); 186 if (ret) 187 dev_err(apb->dev, "Failed to deassert the reset line\n"); 188 189 return ret; 190 } 191 192 static void bt1_apb_disable_clk(void *data) 193 { 194 struct bt1_apb *apb = data; 195 196 clk_disable_unprepare(apb->pclk); 197 } 198 199 static int bt1_apb_request_clk(struct bt1_apb *apb) 200 { 201 int ret; 202 203 apb->pclk = devm_clk_get(apb->dev, "pclk"); 204 if (IS_ERR(apb->pclk)) { 205 dev_err(apb->dev, "Couldn't get APB clock descriptor\n"); 206 return PTR_ERR(apb->pclk); 207 } 208 209 ret = clk_prepare_enable(apb->pclk); 210 if (ret) { 211 dev_err(apb->dev, "Couldn't enable the APB clock\n"); 212 return ret; 213 } 214 215 ret = devm_add_action_or_reset(apb->dev, bt1_apb_disable_clk, apb); 216 if (ret) { 217 dev_err(apb->dev, "Can't add APB EHB clocks disable action\n"); 218 return ret; 219 } 220 221 apb->rate = clk_get_rate(apb->pclk); 222 if (!apb->rate) { 223 dev_err(apb->dev, "Invalid clock rate\n"); 224 return -EINVAL; 225 } 226 227 return 0; 228 } 229 230 static void bt1_apb_clear_irq(void *data) 231 { 232 struct bt1_apb *apb = data; 233 234 regmap_update_bits(apb->regs, APB_EHB_ISR, APB_EHB_ISR_MASK, 0); 235 } 236 237 static int bt1_apb_request_irq(struct bt1_apb *apb) 238 { 239 struct platform_device *pdev = to_platform_device(apb->dev); 240 int ret; 241 242 apb->irq = platform_get_irq(pdev, 0); 243 if (apb->irq < 0) 244 return apb->irq; 245 246 ret = devm_request_irq(apb->dev, apb->irq, bt1_apb_isr, IRQF_SHARED, 247 "bt1-apb", apb); 248 if (ret) { 249 dev_err(apb->dev, "Couldn't request APB EHB IRQ\n"); 250 return ret; 251 } 252 253 ret = devm_add_action(apb->dev, bt1_apb_clear_irq, apb); 254 if (ret) { 255 dev_err(apb->dev, "Can't add APB EHB IRQs clear action\n"); 256 return ret; 257 } 258 259 /* Unmask IRQ and clear it' pending flag. */ 260 regmap_update_bits(apb->regs, APB_EHB_ISR, 261 APB_EHB_ISR_PENDING | APB_EHB_ISR_MASK, 262 APB_EHB_ISR_MASK); 263 264 return 0; 265 } 266 267 static ssize_t count_show(struct device *dev, struct device_attribute *attr, 268 char *buf) 269 { 270 struct bt1_apb *apb = dev_get_drvdata(dev); 271 272 return scnprintf(buf, PAGE_SIZE, "%d\n", atomic_read(&apb->count)); 273 } 274 static DEVICE_ATTR_RO(count); 275 276 static ssize_t timeout_show(struct device *dev, struct device_attribute *attr, 277 char *buf) 278 { 279 struct bt1_apb *apb = dev_get_drvdata(dev); 280 unsigned long timeout; 281 int ret; 282 u32 n; 283 284 ret = regmap_read(apb->regs, APB_EHB_TIMEOUT, &n); 285 if (ret) 286 return ret; 287 288 timeout = bt1_apb_n_to_timeout_us(apb, n); 289 290 return scnprintf(buf, PAGE_SIZE, "%lu\n", timeout); 291 } 292 293 static ssize_t timeout_store(struct device *dev, 294 struct device_attribute *attr, 295 const char *buf, size_t count) 296 { 297 struct bt1_apb *apb = dev_get_drvdata(dev); 298 unsigned long timeout; 299 int ret; 300 u32 n; 301 302 if (kstrtoul(buf, 0, &timeout) < 0) 303 return -EINVAL; 304 305 n = bt1_apb_timeout_to_n_us(apb, timeout); 306 n = clamp(n, APB_EHB_TIMEOUT_MIN, APB_EHB_TIMEOUT_MAX); 307 308 ret = regmap_write(apb->regs, APB_EHB_TIMEOUT, n); 309 310 return ret ?: count; 311 } 312 static DEVICE_ATTR_RW(timeout); 313 314 static ssize_t inject_error_show(struct device *dev, struct device_attribute *attr, 315 char *buf) 316 { 317 return scnprintf(buf, PAGE_SIZE, "Error injection: nodev irq\n"); 318 } 319 320 static ssize_t inject_error_store(struct device *dev, 321 struct device_attribute *attr, 322 const char *data, size_t count) 323 { 324 struct bt1_apb *apb = dev_get_drvdata(dev); 325 326 /* 327 * Either dummy read from the unmapped address in the APB IO area 328 * or manually set the IRQ status. 329 */ 330 if (!strncmp(data, "nodev", 5)) 331 readl(apb->res); 332 else if (!strncmp(data, "irq", 3)) 333 regmap_update_bits(apb->regs, APB_EHB_ISR, APB_EHB_ISR_PENDING, 334 APB_EHB_ISR_PENDING); 335 else 336 return -EINVAL; 337 338 return count; 339 } 340 static DEVICE_ATTR_RW(inject_error); 341 342 static struct attribute *bt1_apb_sysfs_attrs[] = { 343 &dev_attr_count.attr, 344 &dev_attr_timeout.attr, 345 &dev_attr_inject_error.attr, 346 NULL 347 }; 348 ATTRIBUTE_GROUPS(bt1_apb_sysfs); 349 350 static void bt1_apb_remove_sysfs(void *data) 351 { 352 struct bt1_apb *apb = data; 353 354 device_remove_groups(apb->dev, bt1_apb_sysfs_groups); 355 } 356 357 static int bt1_apb_init_sysfs(struct bt1_apb *apb) 358 { 359 int ret; 360 361 ret = device_add_groups(apb->dev, bt1_apb_sysfs_groups); 362 if (ret) { 363 dev_err(apb->dev, "Failed to create EHB APB sysfs nodes\n"); 364 return ret; 365 } 366 367 ret = devm_add_action_or_reset(apb->dev, bt1_apb_remove_sysfs, apb); 368 if (ret) 369 dev_err(apb->dev, "Can't add APB EHB sysfs remove action\n"); 370 371 return ret; 372 } 373 374 static int bt1_apb_probe(struct platform_device *pdev) 375 { 376 struct bt1_apb *apb; 377 int ret; 378 379 apb = bt1_apb_create_data(pdev); 380 if (IS_ERR(apb)) 381 return PTR_ERR(apb); 382 383 ret = bt1_apb_request_regs(apb); 384 if (ret) 385 return ret; 386 387 ret = bt1_apb_request_rst(apb); 388 if (ret) 389 return ret; 390 391 ret = bt1_apb_request_clk(apb); 392 if (ret) 393 return ret; 394 395 ret = bt1_apb_request_irq(apb); 396 if (ret) 397 return ret; 398 399 ret = bt1_apb_init_sysfs(apb); 400 if (ret) 401 return ret; 402 403 return 0; 404 } 405 406 static const struct of_device_id bt1_apb_of_match[] = { 407 { .compatible = "baikal,bt1-apb" }, 408 { } 409 }; 410 MODULE_DEVICE_TABLE(of, bt1_apb_of_match); 411 412 static struct platform_driver bt1_apb_driver = { 413 .probe = bt1_apb_probe, 414 .driver = { 415 .name = "bt1-apb", 416 .of_match_table = bt1_apb_of_match 417 } 418 }; 419 module_platform_driver(bt1_apb_driver); 420 421 MODULE_AUTHOR("Serge Semin <Sergey.Semin@baikalelectronics.ru>"); 422 MODULE_DESCRIPTION("Baikal-T1 APB-bus driver"); 423 MODULE_LICENSE("GPL v2"); 424