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