drivers/bus/bt1-axi.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 AXI-bus driver
   9  */
  10
  11 #include <linux/kernel.h>
  12 #include <linux/module.h>
  13 #include <linux/types.h>
  14 #include <linux/bitfield.h>
  15 #include <linux/device.h>
  16 #include <linux/atomic.h>
  17 #include <linux/regmap.h>
  18 #include <linux/platform_device.h>
  19 #include <linux/mfd/syscon.h>
  20 #include <linux/interrupt.h>
  21 #include <linux/io.h>
  22 #include <linux/nmi.h>
  23 #include <linux/of.h>
  24 #include <linux/clk.h>
  25 #include <linux/reset.h>
  26 #include <linux/sysfs.h>
  27
  28 #define BT1_AXI_WERRL                   0x110
  29 #define BT1_AXI_WERRH                   0x114
  30 #define BT1_AXI_WERRH_TYPE              BIT(23)
  31 #define BT1_AXI_WERRH_ADDR_FLD          24
  32 #define BT1_AXI_WERRH_ADDR_MASK         GENMASK(31, BT1_AXI_WERRH_ADDR_FLD)
  33
  34 /*
  35  * struct bt1_axi - Baikal-T1 AXI-bus private data
  36  * @dev: Pointer to the device structure.
  37  * @qos_regs: AXI Interconnect QoS tuning registers.
  38  * @sys_regs: Baikal-T1 System Controller registers map.
  39  * @irq: Errors IRQ number.
  40  * @aclk: AXI reference clock.
  41  * @arst: AXI Interconnect reset line.
  42  * @count: Number of errors detected.
  43  */
  44 struct bt1_axi {
  45         struct device *dev;
  46
  47         void __iomem *qos_regs;
  48         struct regmap *sys_regs;
  49         int irq;
  50
  51         struct clk *aclk;
  52
  53         struct reset_control *arst;
  54
  55         atomic_t count;
  56 };
  57
  58 static irqreturn_t bt1_axi_isr(int irq, void *data)
  59 {
  60         struct bt1_axi *axi = data;
  61         u32 low = 0, high = 0;
  62
  63         regmap_read(axi->sys_regs, BT1_AXI_WERRL, &low);
  64         regmap_read(axi->sys_regs, BT1_AXI_WERRH, &high);
  65
  66         dev_crit_ratelimited(axi->dev,
  67                 "AXI-bus fault %d: %s at 0x%x%08x\n",
  68                 atomic_inc_return(&axi->count),
  69                 high & BT1_AXI_WERRH_TYPE ? "no slave" : "slave protocol error",
  70                 high, low);
  71
  72         /*
  73          * Print backtrace on each CPU. This might be pointless if the fault
  74          * has happened on the same CPU as the IRQ handler is executed or
  75          * the other core proceeded further execution despite the error.
  76          * But if it's not, by looking at the trace we would get straight to
  77          * the cause of the problem.
  78          */
  79         trigger_all_cpu_backtrace();
  80
  81         return IRQ_HANDLED;
  82 }
  83
  84 static void bt1_axi_clear_data(void *data)
  85 {
  86         struct bt1_axi *axi = data;
  87         struct platform_device *pdev = to_platform_device(axi->dev);
  88
  89         platform_set_drvdata(pdev, NULL);
  90 }
  91
  92 static struct bt1_axi *bt1_axi_create_data(struct platform_device *pdev)
  93 {
  94         struct device *dev = &pdev->dev;
  95         struct bt1_axi *axi;
  96         int ret;
  97
  98         axi = devm_kzalloc(dev, sizeof(*axi), GFP_KERNEL);
  99         if (!axi)
 100                 return ERR_PTR(-ENOMEM);
 101
 102         ret = devm_add_action(dev, bt1_axi_clear_data, axi);
 103         if (ret) {
 104                 dev_err(dev, "Can't add AXI EHB data clear action\n");
 105                 return ERR_PTR(ret);
 106         }
 107
 108         axi->dev = dev;
 109         atomic_set(&axi->count, 0);
 110         platform_set_drvdata(pdev, axi);
 111
 112         return axi;
 113 }
 114
 115 static int bt1_axi_request_regs(struct bt1_axi *axi)
 116 {
 117         struct platform_device *pdev = to_platform_device(axi->dev);
 118         struct device *dev = axi->dev;
 119
 120         axi->sys_regs = syscon_regmap_lookup_by_phandle(dev->of_node, "syscon");
 121         if (IS_ERR(axi->sys_regs)) {
 122                 dev_err(dev, "Couldn't find syscon registers\n");
 123                 return PTR_ERR(axi->sys_regs);
 124         }
 125
 126         axi->qos_regs = devm_platform_ioremap_resource_byname(pdev, "qos");
 127         if (IS_ERR(axi->qos_regs))
 128                 dev_err(dev, "Couldn't map AXI-bus QoS registers\n");
 129
 130         return PTR_ERR_OR_ZERO(axi->qos_regs);
 131 }
 132
 133 static int bt1_axi_request_rst(struct bt1_axi *axi)
 134 {
 135         int ret;
 136
 137         axi->arst = devm_reset_control_get_optional_exclusive(axi->dev, "arst");
 138         if (IS_ERR(axi->arst)) {
 139                 dev_warn(axi->dev, "Couldn't get reset control line\n");
 140                 return PTR_ERR(axi->arst);
 141         }
 142
 143         ret = reset_control_deassert(axi->arst);
 144         if (ret)
 145                 dev_err(axi->dev, "Failed to deassert the reset line\n");
 146
 147         return ret;
 148 }
 149
 150 static void bt1_axi_disable_clk(void *data)
 151 {
 152         struct bt1_axi *axi = data;
 153
 154         clk_disable_unprepare(axi->aclk);
 155 }
 156
 157 static int bt1_axi_request_clk(struct bt1_axi *axi)
 158 {
 159         int ret;
 160
 161         axi->aclk = devm_clk_get(axi->dev, "aclk");
 162         if (IS_ERR(axi->aclk)) {
 163                 dev_err(axi->dev, "Couldn't get AXI Interconnect clock\n");
 164                 return PTR_ERR(axi->aclk);
 165         }
 166
 167         ret = clk_prepare_enable(axi->aclk);
 168         if (ret) {
 169                 dev_err(axi->dev, "Couldn't enable the AXI clock\n");
 170                 return ret;
 171         }
 172
 173         ret = devm_add_action_or_reset(axi->dev, bt1_axi_disable_clk, axi);
 174         if (ret)
 175                 dev_err(axi->dev, "Can't add AXI clock disable action\n");
 176
 177         return ret;
 178 }
 179
 180 static int bt1_axi_request_irq(struct bt1_axi *axi)
 181 {
 182         struct platform_device *pdev = to_platform_device(axi->dev);
 183         int ret;
 184
 185         axi->irq = platform_get_irq(pdev, 0);
 186         if (axi->irq < 0)
 187                 return axi->irq;
 188
 189         ret = devm_request_irq(axi->dev, axi->irq, bt1_axi_isr, IRQF_SHARED,
 190                                "bt1-axi", axi);
 191         if (ret)
 192                 dev_err(axi->dev, "Couldn't request AXI EHB IRQ\n");
 193
 194         return ret;
 195 }
 196
 197 static ssize_t count_show(struct device *dev,
 198                           struct device_attribute *attr, char *buf)
 199 {
 200         struct bt1_axi *axi = dev_get_drvdata(dev);
 201
 202         return scnprintf(buf, PAGE_SIZE, "%d\n", atomic_read(&axi->count));
 203 }
 204 static DEVICE_ATTR_RO(count);
 205
 206 static ssize_t inject_error_show(struct device *dev,
 207                                  struct device_attribute *attr, char *buf)
 208 {
 209         return scnprintf(buf, PAGE_SIZE, "Error injection: bus unaligned\n");
 210 }
 211
 212 static ssize_t inject_error_store(struct device *dev,
 213                                   struct device_attribute *attr,
 214                                   const char *data, size_t count)
 215 {
 216         struct bt1_axi *axi = dev_get_drvdata(dev);
 217
 218         /*
 219          * Performing unaligned read from the memory will cause the CM2 bus
 220          * error while unaligned writing - the AXI bus write error handled
 221          * by this driver.
 222          */
 223         if (sysfs_streq(data, "bus"))
 224                 readb(axi->qos_regs);
 225         else if (sysfs_streq(data, "unaligned"))
 226                 writeb(0, axi->qos_regs);
 227         else
 228                 return -EINVAL;
 229
 230         return count;
 231 }
 232 static DEVICE_ATTR_RW(inject_error);
 233
 234 static struct attribute *bt1_axi_sysfs_attrs[] = {
 235         &dev_attr_count.attr,
 236         &dev_attr_inject_error.attr,
 237         NULL
 238 };
 239 ATTRIBUTE_GROUPS(bt1_axi_sysfs);
 240
 241 static void bt1_axi_remove_sysfs(void *data)
 242 {
 243         struct bt1_axi *axi = data;
 244
 245         device_remove_groups(axi->dev, bt1_axi_sysfs_groups);
 246 }
 247
 248 static int bt1_axi_init_sysfs(struct bt1_axi *axi)
 249 {
 250         int ret;
 251
 252         ret = device_add_groups(axi->dev, bt1_axi_sysfs_groups);
 253         if (ret) {
 254                 dev_err(axi->dev, "Failed to add sysfs files group\n");
 255                 return ret;
 256         }
 257
 258         ret = devm_add_action_or_reset(axi->dev, bt1_axi_remove_sysfs, axi);
 259         if (ret)
 260                 dev_err(axi->dev, "Can't add AXI EHB sysfs remove action\n");
 261
 262         return ret;
 263 }
 264
 265 static int bt1_axi_probe(struct platform_device *pdev)
 266 {
 267         struct bt1_axi *axi;
 268         int ret;
 269
 270         axi = bt1_axi_create_data(pdev);
 271         if (IS_ERR(axi))
 272                 return PTR_ERR(axi);
 273
 274         ret = bt1_axi_request_regs(axi);
 275         if (ret)
 276                 return ret;
 277
 278         ret = bt1_axi_request_rst(axi);
 279         if (ret)
 280                 return ret;
 281
 282         ret = bt1_axi_request_clk(axi);
 283         if (ret)
 284                 return ret;
 285
 286         ret = bt1_axi_request_irq(axi);
 287         if (ret)
 288                 return ret;
 289
 290         ret = bt1_axi_init_sysfs(axi);
 291         if (ret)
 292                 return ret;
 293
 294         return 0;
 295 }
 296
 297 static const struct of_device_id bt1_axi_of_match[] = {
 298         { .compatible = "baikal,bt1-axi" },
 299         { }
 300 };
 301 MODULE_DEVICE_TABLE(of, bt1_axi_of_match);
 302
 303 static struct platform_driver bt1_axi_driver = {
 304         .probe = bt1_axi_probe,
 305         .driver = {
 306                 .name = "bt1-axi",
 307                 .of_match_table = bt1_axi_of_match
 308         }
 309 };
 310 module_platform_driver(bt1_axi_driver);
 311
 312 MODULE_AUTHOR("Serge Semin <Sergey.Semin@baikalelectronics.ru>");
 313 MODULE_DESCRIPTION("Baikal-T1 AXI-bus driver");
 314 MODULE_LICENSE("GPL v2");