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 */ 48struct 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 63static 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 71static 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 81static 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 92static 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 118static 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 126static 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 149static 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"); 169 170 return PTR_ERR_OR_ZERO(apb->res); 171} 172 173static int bt1_apb_request_rst(struct bt1_apb *apb) 174{ 175 int ret; 176 177 apb->prst = devm_reset_control_get_optional_exclusive(apb->dev, "prst"); 178 if (IS_ERR(apb->prst)) { 179 dev_warn(apb->dev, "Couldn't get reset control line\n"); 180 return PTR_ERR(apb->prst); 181 } 182 183 ret = reset_control_deassert(apb->prst); 184 if (ret) 185 dev_err(apb->dev, "Failed to deassert the reset line\n"); 186 187 return ret; 188} 189 190static void bt1_apb_disable_clk(void *data) 191{ 192 struct bt1_apb *apb = data; 193 194 clk_disable_unprepare(apb->pclk); 195} 196 197static int bt1_apb_request_clk(struct bt1_apb *apb) 198{ 199 int ret; 200 201 apb->pclk = devm_clk_get(apb->dev, "pclk"); 202 if (IS_ERR(apb->pclk)) { 203 dev_err(apb->dev, "Couldn't get APB clock descriptor\n"); 204 return PTR_ERR(apb->pclk); 205 } 206 207 ret = clk_prepare_enable(apb->pclk); 208 if (ret) { 209 dev_err(apb->dev, "Couldn't enable the APB clock\n"); 210 return ret; 211 } 212 213 ret = devm_add_action_or_reset(apb->dev, bt1_apb_disable_clk, apb); 214 if (ret) { 215 dev_err(apb->dev, "Can't add APB EHB clocks disable action\n"); 216 return ret; 217 } 218 219 apb->rate = clk_get_rate(apb->pclk); 220 if (!apb->rate) { 221 dev_err(apb->dev, "Invalid clock rate\n"); 222 return -EINVAL; 223 } 224 225 return 0; 226} 227 228static void bt1_apb_clear_irq(void *data) 229{ 230 struct bt1_apb *apb = data; 231 232 regmap_update_bits(apb->regs, APB_EHB_ISR, APB_EHB_ISR_MASK, 0); 233} 234 235static int bt1_apb_request_irq(struct bt1_apb *apb) 236{ 237 struct platform_device *pdev = to_platform_device(apb->dev); 238 int ret; 239 240 apb->irq = platform_get_irq(pdev, 0); 241 if (apb->irq < 0) 242 return apb->irq; 243 244 ret = devm_request_irq(apb->dev, apb->irq, bt1_apb_isr, IRQF_SHARED, 245 "bt1-apb", apb); 246 if (ret) { 247 dev_err(apb->dev, "Couldn't request APB EHB IRQ\n"); 248 return ret; 249 } 250 251 ret = devm_add_action(apb->dev, bt1_apb_clear_irq, apb); 252 if (ret) { 253 dev_err(apb->dev, "Can't add APB EHB IRQs clear action\n"); 254 return ret; 255 } 256 257 /* Unmask IRQ and clear it' pending flag. */ 258 regmap_update_bits(apb->regs, APB_EHB_ISR, 259 APB_EHB_ISR_PENDING | APB_EHB_ISR_MASK, 260 APB_EHB_ISR_MASK); 261 262 return 0; 263} 264 265static ssize_t count_show(struct device *dev, struct device_attribute *attr, 266 char *buf) 267{ 268 struct bt1_apb *apb = dev_get_drvdata(dev); 269 270 return scnprintf(buf, PAGE_SIZE, "%d\n", atomic_read(&apb->count)); 271} 272static DEVICE_ATTR_RO(count); 273 274static ssize_t timeout_show(struct device *dev, struct device_attribute *attr, 275 char *buf) 276{ 277 struct bt1_apb *apb = dev_get_drvdata(dev); 278 unsigned long timeout; 279 int ret; 280 u32 n; 281 282 ret = regmap_read(apb->regs, APB_EHB_TIMEOUT, &n); 283 if (ret) 284 return ret; 285 286 timeout = bt1_apb_n_to_timeout_us(apb, n); 287 288 return scnprintf(buf, PAGE_SIZE, "%lu\n", timeout); 289} 290 291static ssize_t timeout_store(struct device *dev, 292 struct device_attribute *attr, 293 const char *buf, size_t count) 294{ 295 struct bt1_apb *apb = dev_get_drvdata(dev); 296 unsigned long timeout; 297 int ret; 298 u32 n; 299 300 if (kstrtoul(buf, 0, &timeout) < 0) 301 return -EINVAL; 302 303 n = bt1_apb_timeout_to_n_us(apb, timeout); 304 n = clamp(n, APB_EHB_TIMEOUT_MIN, APB_EHB_TIMEOUT_MAX); 305 306 ret = regmap_write(apb->regs, APB_EHB_TIMEOUT, n); 307 308 return ret ?: count; 309} 310static DEVICE_ATTR_RW(timeout); 311 312static ssize_t inject_error_show(struct device *dev, 313 struct device_attribute *attr, char *buf) 314{ 315 return scnprintf(buf, PAGE_SIZE, "Error injection: nodev irq\n"); 316} 317 318static ssize_t inject_error_store(struct device *dev, 319 struct device_attribute *attr, 320 const char *data, size_t count) 321{ 322 struct bt1_apb *apb = dev_get_drvdata(dev); 323 324 /* 325 * Either dummy read from the unmapped address in the APB IO area 326 * or manually set the IRQ status. 327 */ 328 if (sysfs_streq(data, "nodev")) 329 readl(apb->res); 330 else if (sysfs_streq(data, "irq")) 331 regmap_update_bits(apb->regs, APB_EHB_ISR, APB_EHB_ISR_PENDING, 332 APB_EHB_ISR_PENDING); 333 else 334 return -EINVAL; 335 336 return count; 337} 338static DEVICE_ATTR_RW(inject_error); 339 340static struct attribute *bt1_apb_sysfs_attrs[] = { 341 &dev_attr_count.attr, 342 &dev_attr_timeout.attr, 343 &dev_attr_inject_error.attr, 344 NULL 345}; 346ATTRIBUTE_GROUPS(bt1_apb_sysfs); 347 348static void bt1_apb_remove_sysfs(void *data) 349{ 350 struct bt1_apb *apb = data; 351 352 device_remove_groups(apb->dev, bt1_apb_sysfs_groups); 353} 354 355static int bt1_apb_init_sysfs(struct bt1_apb *apb) 356{ 357 int ret; 358 359 ret = device_add_groups(apb->dev, bt1_apb_sysfs_groups); 360 if (ret) { 361 dev_err(apb->dev, "Failed to create EHB APB sysfs nodes\n"); 362 return ret; 363 } 364 365 ret = devm_add_action_or_reset(apb->dev, bt1_apb_remove_sysfs, apb); 366 if (ret) 367 dev_err(apb->dev, "Can't add APB EHB sysfs remove action\n"); 368 369 return ret; 370} 371 372static int bt1_apb_probe(struct platform_device *pdev) 373{ 374 struct bt1_apb *apb; 375 int ret; 376 377 apb = bt1_apb_create_data(pdev); 378 if (IS_ERR(apb)) 379 return PTR_ERR(apb); 380 381 ret = bt1_apb_request_regs(apb); 382 if (ret) 383 return ret; 384 385 ret = bt1_apb_request_rst(apb); 386 if (ret) 387 return ret; 388 389 ret = bt1_apb_request_clk(apb); 390 if (ret) 391 return ret; 392 393 ret = bt1_apb_request_irq(apb); 394 if (ret) 395 return ret; 396 397 ret = bt1_apb_init_sysfs(apb); 398 if (ret) 399 return ret; 400 401 return 0; 402} 403 404static const struct of_device_id bt1_apb_of_match[] = { 405 { .compatible = "baikal,bt1-apb" }, 406 { } 407}; 408MODULE_DEVICE_TABLE(of, bt1_apb_of_match); 409 410static struct platform_driver bt1_apb_driver = { 411 .probe = bt1_apb_probe, 412 .driver = { 413 .name = "bt1-apb", 414 .of_match_table = bt1_apb_of_match 415 } 416}; 417module_platform_driver(bt1_apb_driver); 418 419MODULE_AUTHOR("Serge Semin <Sergey.Semin@baikalelectronics.ru>"); 420MODULE_DESCRIPTION("Baikal-T1 APB-bus driver"); 421MODULE_LICENSE("GPL v2"); 422