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