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