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/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"); 168 169 return PTR_ERR_OR_ZERO(apb->res); 170 } 171 172 static int bt1_apb_request_rst(struct bt1_apb *apb) 173 { 174 int ret; 175 176 apb->prst = devm_reset_control_get_optional_exclusive(apb->dev, "prst"); 177 if (IS_ERR(apb->prst)) 178 return dev_err_probe(apb->dev, PTR_ERR(apb->prst), 179 "Couldn't get reset control line\n"); 180 181 ret = reset_control_deassert(apb->prst); 182 if (ret) 183 dev_err(apb->dev, "Failed to deassert the reset line\n"); 184 185 return ret; 186 } 187 188 static void bt1_apb_disable_clk(void *data) 189 { 190 struct bt1_apb *apb = data; 191 192 clk_disable_unprepare(apb->pclk); 193 } 194 195 static int bt1_apb_request_clk(struct bt1_apb *apb) 196 { 197 int ret; 198 199 apb->pclk = devm_clk_get(apb->dev, "pclk"); 200 if (IS_ERR(apb->pclk)) 201 return dev_err_probe(apb->dev, PTR_ERR(apb->pclk), 202 "Couldn't get APB clock descriptor\n"); 203 204 ret = clk_prepare_enable(apb->pclk); 205 if (ret) { 206 dev_err(apb->dev, "Couldn't enable the APB clock\n"); 207 return ret; 208 } 209 210 ret = devm_add_action_or_reset(apb->dev, bt1_apb_disable_clk, apb); 211 if (ret) { 212 dev_err(apb->dev, "Can't add APB EHB clocks disable action\n"); 213 return ret; 214 } 215 216 apb->rate = clk_get_rate(apb->pclk); 217 if (!apb->rate) { 218 dev_err(apb->dev, "Invalid clock rate\n"); 219 return -EINVAL; 220 } 221 222 return 0; 223 } 224 225 static void bt1_apb_clear_irq(void *data) 226 { 227 struct bt1_apb *apb = data; 228 229 regmap_update_bits(apb->regs, APB_EHB_ISR, APB_EHB_ISR_MASK, 0); 230 } 231 232 static int bt1_apb_request_irq(struct bt1_apb *apb) 233 { 234 struct platform_device *pdev = to_platform_device(apb->dev); 235 int ret; 236 237 apb->irq = platform_get_irq(pdev, 0); 238 if (apb->irq < 0) 239 return apb->irq; 240 241 ret = devm_request_irq(apb->dev, apb->irq, bt1_apb_isr, IRQF_SHARED, 242 "bt1-apb", apb); 243 if (ret) { 244 dev_err(apb->dev, "Couldn't request APB EHB IRQ\n"); 245 return ret; 246 } 247 248 ret = devm_add_action(apb->dev, bt1_apb_clear_irq, apb); 249 if (ret) { 250 dev_err(apb->dev, "Can't add APB EHB IRQs clear action\n"); 251 return ret; 252 } 253 254 /* Unmask IRQ and clear it' pending flag. */ 255 regmap_update_bits(apb->regs, APB_EHB_ISR, 256 APB_EHB_ISR_PENDING | APB_EHB_ISR_MASK, 257 APB_EHB_ISR_MASK); 258 259 return 0; 260 } 261 262 static ssize_t count_show(struct device *dev, struct device_attribute *attr, 263 char *buf) 264 { 265 struct bt1_apb *apb = dev_get_drvdata(dev); 266 267 return scnprintf(buf, PAGE_SIZE, "%d\n", atomic_read(&apb->count)); 268 } 269 static DEVICE_ATTR_RO(count); 270 271 static ssize_t timeout_show(struct device *dev, struct device_attribute *attr, 272 char *buf) 273 { 274 struct bt1_apb *apb = dev_get_drvdata(dev); 275 unsigned long timeout; 276 int ret; 277 u32 n; 278 279 ret = regmap_read(apb->regs, APB_EHB_TIMEOUT, &n); 280 if (ret) 281 return ret; 282 283 timeout = bt1_apb_n_to_timeout_us(apb, n); 284 285 return scnprintf(buf, PAGE_SIZE, "%lu\n", timeout); 286 } 287 288 static ssize_t timeout_store(struct device *dev, 289 struct device_attribute *attr, 290 const char *buf, size_t count) 291 { 292 struct bt1_apb *apb = dev_get_drvdata(dev); 293 unsigned long timeout; 294 int ret; 295 u32 n; 296 297 if (kstrtoul(buf, 0, &timeout) < 0) 298 return -EINVAL; 299 300 n = bt1_apb_timeout_to_n_us(apb, timeout); 301 n = clamp(n, APB_EHB_TIMEOUT_MIN, APB_EHB_TIMEOUT_MAX); 302 303 ret = regmap_write(apb->regs, APB_EHB_TIMEOUT, n); 304 305 return ret ?: count; 306 } 307 static DEVICE_ATTR_RW(timeout); 308 309 static ssize_t inject_error_show(struct device *dev, 310 struct device_attribute *attr, char *buf) 311 { 312 return scnprintf(buf, PAGE_SIZE, "Error injection: nodev irq\n"); 313 } 314 315 static ssize_t inject_error_store(struct device *dev, 316 struct device_attribute *attr, 317 const char *data, size_t count) 318 { 319 struct bt1_apb *apb = dev_get_drvdata(dev); 320 321 /* 322 * Either dummy read from the unmapped address in the APB IO area 323 * or manually set the IRQ status. 324 */ 325 if (sysfs_streq(data, "nodev")) 326 readl(apb->res); 327 else if (sysfs_streq(data, "irq")) 328 regmap_update_bits(apb->regs, APB_EHB_ISR, APB_EHB_ISR_PENDING, 329 APB_EHB_ISR_PENDING); 330 else 331 return -EINVAL; 332 333 return count; 334 } 335 static DEVICE_ATTR_RW(inject_error); 336 337 static struct attribute *bt1_apb_sysfs_attrs[] = { 338 &dev_attr_count.attr, 339 &dev_attr_timeout.attr, 340 &dev_attr_inject_error.attr, 341 NULL 342 }; 343 ATTRIBUTE_GROUPS(bt1_apb_sysfs); 344 345 static void bt1_apb_remove_sysfs(void *data) 346 { 347 struct bt1_apb *apb = data; 348 349 device_remove_groups(apb->dev, bt1_apb_sysfs_groups); 350 } 351 352 static int bt1_apb_init_sysfs(struct bt1_apb *apb) 353 { 354 int ret; 355 356 ret = device_add_groups(apb->dev, bt1_apb_sysfs_groups); 357 if (ret) { 358 dev_err(apb->dev, "Failed to create EHB APB sysfs nodes\n"); 359 return ret; 360 } 361 362 ret = devm_add_action_or_reset(apb->dev, bt1_apb_remove_sysfs, apb); 363 if (ret) 364 dev_err(apb->dev, "Can't add APB EHB sysfs remove action\n"); 365 366 return ret; 367 } 368 369 static int bt1_apb_probe(struct platform_device *pdev) 370 { 371 struct bt1_apb *apb; 372 int ret; 373 374 apb = bt1_apb_create_data(pdev); 375 if (IS_ERR(apb)) 376 return PTR_ERR(apb); 377 378 ret = bt1_apb_request_regs(apb); 379 if (ret) 380 return ret; 381 382 ret = bt1_apb_request_rst(apb); 383 if (ret) 384 return ret; 385 386 ret = bt1_apb_request_clk(apb); 387 if (ret) 388 return ret; 389 390 ret = bt1_apb_request_irq(apb); 391 if (ret) 392 return ret; 393 394 ret = bt1_apb_init_sysfs(apb); 395 if (ret) 396 return ret; 397 398 return 0; 399 } 400 401 static const struct of_device_id bt1_apb_of_match[] = { 402 { .compatible = "baikal,bt1-apb" }, 403 { } 404 }; 405 MODULE_DEVICE_TABLE(of, bt1_apb_of_match); 406 407 static struct platform_driver bt1_apb_driver = { 408 .probe = bt1_apb_probe, 409 .driver = { 410 .name = "bt1-apb", 411 .of_match_table = bt1_apb_of_match 412 } 413 }; 414 module_platform_driver(bt1_apb_driver); 415 416 MODULE_AUTHOR("Serge Semin <Sergey.Semin@baikalelectronics.ru>"); 417 MODULE_DESCRIPTION("Baikal-T1 APB-bus driver"); 418