drivers/bus/bt1-apb.c

   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
 170         return PTR_ERR_OR_ZERO(apb->res);
 171 }
 172
 173 static 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
 190 static void bt1_apb_disable_clk(void *data)
 191 {
 192         struct bt1_apb *apb = data;
 193
 194         clk_disable_unprepare(apb->pclk);
 195 }
 196
 197 static 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
 228 static 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
 235 static 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
 265 static 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 }
 272 static DEVICE_ATTR_RO(count);
 273
 274 static 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
 291 static 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 }
 310 static DEVICE_ATTR_RW(timeout);
 311
 312 static 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
 318 static 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 }
 338 static DEVICE_ATTR_RW(inject_error);
 339
 340 static 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 };
 346 ATTRIBUTE_GROUPS(bt1_apb_sysfs);
 347
 348 static 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
 355 static 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
 372 static 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
 404 static const struct of_device_id bt1_apb_of_match[] = {
 405         { .compatible = "baikal,bt1-apb" },
 406         { }
 407 };
 408 MODULE_DEVICE_TABLE(of, bt1_apb_of_match);
 409
 410 static 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 };
 417 module_platform_driver(bt1_apb_driver);
 418
 419 MODULE_AUTHOR("Serge Semin <Sergey.Semin@baikalelectronics.ru>");
 420 MODULE_DESCRIPTION("Baikal-T1 APB-bus driver");
 421 MODULE_LICENSE("GPL v2");