drivers/watchdog/of_xilinx_wdt.c

   1 // SPDX-License-Identifier: GPL-2.0+
   2 /*
   3  * Watchdog Device Driver for Xilinx axi/xps_timebase_wdt
   4  *
   5  * (C) Copyright 2013 - 2014 Xilinx, Inc.
   6  * (C) Copyright 2011 (Alejandro Cabrera <aldaya@gmail.com>)
   7  */
   8
   9 #include <linux/clk.h>
  10 #include <linux/err.h>
  11 #include <linux/module.h>
  12 #include <linux/types.h>
  13 #include <linux/kernel.h>
  14 #include <linux/ioport.h>
  15 #include <linux/watchdog.h>
  16 #include <linux/io.h>
  17 #include <linux/of.h>
  18 #include <linux/of_device.h>
  19 #include <linux/of_address.h>
  20
  21 /* Register offsets for the Wdt device */
  22 #define XWT_TWCSR0_OFFSET   0x0 /* Control/Status Register0 */
  23 #define XWT_TWCSR1_OFFSET   0x4 /* Control/Status Register1 */
  24 #define XWT_TBR_OFFSET      0x8 /* Timebase Register Offset */
  25
  26 /* Control/Status Register Masks  */
  27 #define XWT_CSR0_WRS_MASK   0x00000008 /* Reset status */
  28 #define XWT_CSR0_WDS_MASK   0x00000004 /* Timer state  */
  29 #define XWT_CSR0_EWDT1_MASK 0x00000002 /* Enable bit 1 */
  30
  31 /* Control/Status Register 0/1 bits  */
  32 #define XWT_CSRX_EWDT2_MASK 0x00000001 /* Enable bit 2 */
  33
  34 /* SelfTest constants */
  35 #define XWT_MAX_SELFTEST_LOOP_COUNT 0x00010000
  36 #define XWT_TIMER_FAILED            0xFFFFFFFF
  37
  38 #define WATCHDOG_NAME     "Xilinx Watchdog"
  39
  40 struct xwdt_device {
  41         void __iomem *base;
  42         u32 wdt_interval;
  43         spinlock_t spinlock;
  44         struct watchdog_device xilinx_wdt_wdd;
  45         struct clk              *clk;
  46 };
  47
  48 static int xilinx_wdt_start(struct watchdog_device *wdd)
  49 {
  50         int ret;
  51         u32 control_status_reg;
  52         struct xwdt_device *xdev = watchdog_get_drvdata(wdd);
  53
  54         ret = clk_enable(xdev->clk);
  55         if (ret) {
  56                 dev_err(wdd->parent, "Failed to enable clock\n");
  57                 return ret;
  58         }
  59
  60         spin_lock(&xdev->spinlock);
  61
  62         /* Clean previous status and enable the watchdog timer */
  63         control_status_reg = ioread32(xdev->base + XWT_TWCSR0_OFFSET);
  64         control_status_reg |= (XWT_CSR0_WRS_MASK | XWT_CSR0_WDS_MASK);
  65
  66         iowrite32((control_status_reg | XWT_CSR0_EWDT1_MASK),
  67                   xdev->base + XWT_TWCSR0_OFFSET);
  68
  69         iowrite32(XWT_CSRX_EWDT2_MASK, xdev->base + XWT_TWCSR1_OFFSET);
  70
  71         spin_unlock(&xdev->spinlock);
  72
  73         return 0;
  74 }
  75
  76 static int xilinx_wdt_stop(struct watchdog_device *wdd)
  77 {
  78         u32 control_status_reg;
  79         struct xwdt_device *xdev = watchdog_get_drvdata(wdd);
  80
  81         spin_lock(&xdev->spinlock);
  82
  83         control_status_reg = ioread32(xdev->base + XWT_TWCSR0_OFFSET);
  84
  85         iowrite32((control_status_reg & ~XWT_CSR0_EWDT1_MASK),
  86                   xdev->base + XWT_TWCSR0_OFFSET);
  87
  88         iowrite32(0, xdev->base + XWT_TWCSR1_OFFSET);
  89
  90         spin_unlock(&xdev->spinlock);
  91
  92         clk_disable(xdev->clk);
  93
  94         pr_info("Stopped!\n");
  95
  96         return 0;
  97 }
  98
  99 static int xilinx_wdt_keepalive(struct watchdog_device *wdd)
 100 {
 101         u32 control_status_reg;
 102         struct xwdt_device *xdev = watchdog_get_drvdata(wdd);
 103
 104         spin_lock(&xdev->spinlock);
 105
 106         control_status_reg = ioread32(xdev->base + XWT_TWCSR0_OFFSET);
 107         control_status_reg |= (XWT_CSR0_WRS_MASK | XWT_CSR0_WDS_MASK);
 108         iowrite32(control_status_reg, xdev->base + XWT_TWCSR0_OFFSET);
 109
 110         spin_unlock(&xdev->spinlock);
 111
 112         return 0;
 113 }
 114
 115 static const struct watchdog_info xilinx_wdt_ident = {
 116         .options =  WDIOF_MAGICCLOSE |
 117                     WDIOF_KEEPALIVEPING,
 118         .firmware_version =     1,
 119         .identity =     WATCHDOG_NAME,
 120 };
 121
 122 static const struct watchdog_ops xilinx_wdt_ops = {
 123         .owner = THIS_MODULE,
 124         .start = xilinx_wdt_start,
 125         .stop = xilinx_wdt_stop,
 126         .ping = xilinx_wdt_keepalive,
 127 };
 128
 129 static u32 xwdt_selftest(struct xwdt_device *xdev)
 130 {
 131         int i;
 132         u32 timer_value1;
 133         u32 timer_value2;
 134
 135         spin_lock(&xdev->spinlock);
 136
 137         timer_value1 = ioread32(xdev->base + XWT_TBR_OFFSET);
 138         timer_value2 = ioread32(xdev->base + XWT_TBR_OFFSET);
 139
 140         for (i = 0;
 141                 ((i <= XWT_MAX_SELFTEST_LOOP_COUNT) &&
 142                         (timer_value2 == timer_value1)); i++) {
 143                 timer_value2 = ioread32(xdev->base + XWT_TBR_OFFSET);
 144         }
 145
 146         spin_unlock(&xdev->spinlock);
 147
 148         if (timer_value2 != timer_value1)
 149                 return ~XWT_TIMER_FAILED;
 150         else
 151                 return XWT_TIMER_FAILED;
 152 }
 153
 154 static int xwdt_probe(struct platform_device *pdev)
 155 {
 156         int rc;
 157         u32 pfreq = 0, enable_once = 0;
 158         struct resource *res;
 159         struct xwdt_device *xdev;
 160         struct watchdog_device *xilinx_wdt_wdd;
 161
 162         xdev = devm_kzalloc(&pdev->dev, sizeof(*xdev), GFP_KERNEL);
 163         if (!xdev)
 164                 return -ENOMEM;
 165
 166         xilinx_wdt_wdd = &xdev->xilinx_wdt_wdd;
 167         xilinx_wdt_wdd->info = &xilinx_wdt_ident;
 168         xilinx_wdt_wdd->ops = &xilinx_wdt_ops;
 169         xilinx_wdt_wdd->parent = &pdev->dev;
 170
 171         res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
 172         xdev->base = devm_ioremap_resource(&pdev->dev, res);
 173         if (IS_ERR(xdev->base))
 174                 return PTR_ERR(xdev->base);
 175
 176         rc = of_property_read_u32(pdev->dev.of_node, "xlnx,wdt-interval",
 177                                   &xdev->wdt_interval);
 178         if (rc)
 179                 dev_warn(&pdev->dev,
 180                          "Parameter \"xlnx,wdt-interval\" not found\n");
 181
 182         rc = of_property_read_u32(pdev->dev.of_node, "xlnx,wdt-enable-once",
 183                                   &enable_once);
 184         if (rc)
 185                 dev_warn(&pdev->dev,
 186                          "Parameter \"xlnx,wdt-enable-once\" not found\n");
 187
 188         watchdog_set_nowayout(xilinx_wdt_wdd, enable_once);
 189
 190         xdev->clk = devm_clk_get(&pdev->dev, NULL);
 191         if (IS_ERR(xdev->clk)) {
 192                 if (PTR_ERR(xdev->clk) != -ENOENT)
 193                         return PTR_ERR(xdev->clk);
 194
 195                 /*
 196                  * Clock framework support is optional, continue on
 197                  * anyways if we don't find a matching clock.
 198                  */
 199                 xdev->clk = NULL;
 200
 201                 rc = of_property_read_u32(pdev->dev.of_node, "clock-frequency",
 202                                           &pfreq);
 203                 if (rc)
 204                         dev_warn(&pdev->dev,
 205                                  "The watchdog clock freq cannot be obtained\n");
 206         } else {
 207                 pfreq = clk_get_rate(xdev->clk);
 208         }
 209
 210         /*
 211          * Twice of the 2^wdt_interval / freq  because the first wdt overflow is
 212          * ignored (interrupt), reset is only generated at second wdt overflow
 213          */
 214         if (pfreq && xdev->wdt_interval)
 215                 xilinx_wdt_wdd->timeout = 2 * ((1 << xdev->wdt_interval) /
 216                                           pfreq);
 217
 218         spin_lock_init(&xdev->spinlock);
 219         watchdog_set_drvdata(xilinx_wdt_wdd, xdev);
 220
 221         rc = clk_prepare_enable(xdev->clk);
 222         if (rc) {
 223                 dev_err(&pdev->dev, "unable to enable clock\n");
 224                 return rc;
 225         }
 226
 227         rc = xwdt_selftest(xdev);
 228         if (rc == XWT_TIMER_FAILED) {
 229                 dev_err(&pdev->dev, "SelfTest routine error\n");
 230                 goto err_clk_disable;
 231         }
 232
 233         rc = watchdog_register_device(xilinx_wdt_wdd);
 234         if (rc) {
 235                 dev_err(&pdev->dev, "Cannot register watchdog (err=%d)\n", rc);
 236                 goto err_clk_disable;
 237         }
 238
 239         clk_disable(xdev->clk);
 240
 241         dev_info(&pdev->dev, "Xilinx Watchdog Timer at %p with timeout %ds\n",
 242                  xdev->base, xilinx_wdt_wdd->timeout);
 243
 244         platform_set_drvdata(pdev, xdev);
 245
 246         return 0;
 247 err_clk_disable:
 248         clk_disable_unprepare(xdev->clk);
 249
 250         return rc;
 251 }
 252
 253 static int xwdt_remove(struct platform_device *pdev)
 254 {
 255         struct xwdt_device *xdev = platform_get_drvdata(pdev);
 256
 257         watchdog_unregister_device(&xdev->xilinx_wdt_wdd);
 258         clk_disable_unprepare(xdev->clk);
 259
 260         return 0;
 261 }
 262
 263 /**
 264  * xwdt_suspend - Suspend the device.
 265  *
 266  * @dev: handle to the device structure.
 267  * Return: 0 always.
 268  */
 269 static int __maybe_unused xwdt_suspend(struct device *dev)
 270 {
 271         struct xwdt_device *xdev = dev_get_drvdata(dev);
 272
 273         if (watchdog_active(&xdev->xilinx_wdt_wdd))
 274                 xilinx_wdt_stop(&xdev->xilinx_wdt_wdd);
 275
 276         return 0;
 277 }
 278
 279 /**
 280  * xwdt_resume - Resume the device.
 281  *
 282  * @dev: handle to the device structure.
 283  * Return: 0 on success, errno otherwise.
 284  */
 285 static int __maybe_unused xwdt_resume(struct device *dev)
 286 {
 287         struct xwdt_device *xdev = dev_get_drvdata(dev);
 288         int ret = 0;
 289
 290         if (watchdog_active(&xdev->xilinx_wdt_wdd))
 291                 ret = xilinx_wdt_start(&xdev->xilinx_wdt_wdd);
 292
 293         return ret;
 294 }
 295
 296 static SIMPLE_DEV_PM_OPS(xwdt_pm_ops, xwdt_suspend, xwdt_resume);
 297
 298 /* Match table for of_platform binding */
 299 static const struct of_device_id xwdt_of_match[] = {
 300         { .compatible = "xlnx,xps-timebase-wdt-1.00.a", },
 301         { .compatible = "xlnx,xps-timebase-wdt-1.01.a", },
 302         {},
 303 };
 304 MODULE_DEVICE_TABLE(of, xwdt_of_match);
 305
 306 static struct platform_driver xwdt_driver = {
 307         .probe       = xwdt_probe,
 308         .remove      = xwdt_remove,
 309         .driver = {
 310                 .name  = WATCHDOG_NAME,
 311                 .of_match_table = xwdt_of_match,
 312                 .pm = &xwdt_pm_ops,
 313         },
 314 };
 315
 316 module_platform_driver(xwdt_driver);
 317
 318 MODULE_AUTHOR("Alejandro Cabrera <aldaya@gmail.com>");
 319 MODULE_DESCRIPTION("Xilinx Watchdog driver");
 320 MODULE_LICENSE("GPL");