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                 return dev_err_probe(axi->dev, PTR_ERR(axi->arst),
 140                                      "Couldn't get reset control line\n");
 141
 142         ret = reset_control_deassert(axi->arst);
 143         if (ret)
 144                 dev_err(axi->dev, "Failed to deassert the reset line\n");
 145
 146         return ret;
 147 }
 148
 149 static int bt1_axi_request_clk(struct bt1_axi *axi)
 150 {
 151         axi->aclk = devm_clk_get_enabled(axi->dev, "aclk");
 152         if (IS_ERR(axi->aclk))
 153                 return dev_err_probe(axi->dev, PTR_ERR(axi->aclk),
 154                                      "Couldn't get AXI Interconnect clock\n");
 155
 156         return 0;
 157 }
 158
 159 static int bt1_axi_request_irq(struct bt1_axi *axi)
 160 {
 161         struct platform_device *pdev = to_platform_device(axi->dev);
 162         int ret;
 163
 164         axi->irq = platform_get_irq(pdev, 0);
 165         if (axi->irq < 0)
 166                 return axi->irq;
 167
 168         ret = devm_request_irq(axi->dev, axi->irq, bt1_axi_isr, IRQF_SHARED,
 169                                "bt1-axi", axi);
 170         if (ret)
 171                 dev_err(axi->dev, "Couldn't request AXI EHB IRQ\n");
 172
 173         return ret;
 174 }
 175
 176 static ssize_t count_show(struct device *dev,
 177                           struct device_attribute *attr, char *buf)
 178 {
 179         struct bt1_axi *axi = dev_get_drvdata(dev);
 180
 181         return scnprintf(buf, PAGE_SIZE, "%d\n", atomic_read(&axi->count));
 182 }
 183 static DEVICE_ATTR_RO(count);
 184
 185 static ssize_t inject_error_show(struct device *dev,
 186                                  struct device_attribute *attr, char *buf)
 187 {
 188         return scnprintf(buf, PAGE_SIZE, "Error injection: bus unaligned\n");
 189 }
 190
 191 static ssize_t inject_error_store(struct device *dev,
 192                                   struct device_attribute *attr,
 193                                   const char *data, size_t count)
 194 {
 195         struct bt1_axi *axi = dev_get_drvdata(dev);
 196
 197         /*
 198          * Performing unaligned read from the memory will cause the CM2 bus
 199          * error while unaligned writing - the AXI bus write error handled
 200          * by this driver.
 201          */
 202         if (sysfs_streq(data, "bus"))
 203                 readb(axi->qos_regs);
 204         else if (sysfs_streq(data, "unaligned"))
 205                 writeb(0, axi->qos_regs);
 206         else
 207                 return -EINVAL;
 208
 209         return count;
 210 }
 211 static DEVICE_ATTR_RW(inject_error);
 212
 213 static struct attribute *bt1_axi_sysfs_attrs[] = {
 214         &dev_attr_count.attr,
 215         &dev_attr_inject_error.attr,
 216         NULL
 217 };
 218 ATTRIBUTE_GROUPS(bt1_axi_sysfs);
 219
 220 static void bt1_axi_remove_sysfs(void *data)
 221 {
 222         struct bt1_axi *axi = data;
 223
 224         device_remove_groups(axi->dev, bt1_axi_sysfs_groups);
 225 }
 226
 227 static int bt1_axi_init_sysfs(struct bt1_axi *axi)
 228 {
 229         int ret;
 230
 231         ret = device_add_groups(axi->dev, bt1_axi_sysfs_groups);
 232         if (ret) {
 233                 dev_err(axi->dev, "Failed to add sysfs files group\n");
 234                 return ret;
 235         }
 236
 237         ret = devm_add_action_or_reset(axi->dev, bt1_axi_remove_sysfs, axi);
 238         if (ret)
 239                 dev_err(axi->dev, "Can't add AXI EHB sysfs remove action\n");
 240
 241         return ret;
 242 }
 243
 244 static int bt1_axi_probe(struct platform_device *pdev)
 245 {
 246         struct bt1_axi *axi;
 247         int ret;
 248
 249         axi = bt1_axi_create_data(pdev);
 250         if (IS_ERR(axi))
 251                 return PTR_ERR(axi);
 252
 253         ret = bt1_axi_request_regs(axi);
 254         if (ret)
 255                 return ret;
 256
 257         ret = bt1_axi_request_rst(axi);
 258         if (ret)
 259                 return ret;
 260
 261         ret = bt1_axi_request_clk(axi);
 262         if (ret)
 263                 return ret;
 264
 265         ret = bt1_axi_request_irq(axi);
 266         if (ret)
 267                 return ret;
 268
 269         ret = bt1_axi_init_sysfs(axi);
 270         if (ret)
 271                 return ret;
 272
 273         return 0;
 274 }
 275
 276 static const struct of_device_id bt1_axi_of_match[] = {
 277         { .compatible = "baikal,bt1-axi" },
 278         { }
 279 };
 280 MODULE_DEVICE_TABLE(of, bt1_axi_of_match);
 281
 282 static struct platform_driver bt1_axi_driver = {
 283         .probe = bt1_axi_probe,
 284         .driver = {
 285                 .name = "bt1-axi",
 286                 .of_match_table = bt1_axi_of_match
 287         }
 288 };
 289 module_platform_driver(bt1_axi_driver);
 290
 291 MODULE_AUTHOR("Serge Semin <Sergey.Semin@baikalelectronics.ru>");
 292 MODULE_DESCRIPTION("Baikal-T1 AXI-bus driver");