drivers/watchdog/xilinx_wwdt.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  * Window watchdog device driver for Xilinx Versal WWDT
   4  *
   5  * Copyright (C) 2022 - 2024, Advanced Micro Devices, Inc.
   6  */
   7
   8 #include <linux/clk.h>
   9 #include <linux/interrupt.h>
  10 #include <linux/io.h>
  11 #include <linux/ioport.h>
  12 #include <linux/math64.h>
  13 #include <linux/mod_devicetable.h>
  14 #include <linux/module.h>
  15 #include <linux/platform_device.h>
  16 #include <linux/watchdog.h>
  17
  18 /* Max timeout is calculated at 100MHz source clock */
  19 #define XWWDT_DEFAULT_TIMEOUT   42
  20 #define XWWDT_MIN_TIMEOUT       1
  21
  22 /* Register offsets for the WWDT device */
  23 #define XWWDT_MWR_OFFSET        0x00
  24 #define XWWDT_ESR_OFFSET        0x04
  25 #define XWWDT_FCR_OFFSET        0x08
  26 #define XWWDT_FWR_OFFSET        0x0c
  27 #define XWWDT_SWR_OFFSET        0x10
  28
  29 /* Master Write Control Register Masks */
  30 #define XWWDT_MWR_MASK          BIT(0)
  31
  32 /* Enable and Status Register Masks */
  33 #define XWWDT_ESR_WINT_MASK     BIT(16)
  34 #define XWWDT_ESR_WSW_MASK      BIT(8)
  35 #define XWWDT_ESR_WEN_MASK      BIT(0)
  36
  37 #define XWWDT_CLOSE_WINDOW_PERCENT      50
  38
  39 /* Maximum count value of each 32 bit window */
  40 #define XWWDT_MAX_COUNT_WINDOW          GENMASK(31, 0)
  41
  42 /* Maximum count value of closed and open window combined */
  43 #define XWWDT_MAX_COUNT_WINDOW_COMBINED GENMASK_ULL(32, 1)
  44
  45 static int wwdt_timeout;
  46 static int closed_window_percent;
  47
  48 module_param(wwdt_timeout, int, 0);
  49 MODULE_PARM_DESC(wwdt_timeout,
  50                  "Watchdog time in seconds. (default="
  51                  __MODULE_STRING(XWWDT_DEFAULT_TIMEOUT) ")");
  52 module_param(closed_window_percent, int, 0);
  53 MODULE_PARM_DESC(closed_window_percent,
  54                  "Watchdog closed window percentage. (default="
  55                  __MODULE_STRING(XWWDT_CLOSE_WINDOW_PERCENT) ")");
  56 /**
  57  * struct xwwdt_device - Watchdog device structure
  58  * @base: base io address of WDT device
  59  * @spinlock: spinlock for IO register access
  60  * @xilinx_wwdt_wdd: watchdog device structure
  61  * @freq: source clock frequency of WWDT
  62  * @close_percent: Closed window percent
  63  * @closed_timeout: Closed window timeout in ticks
  64  * @open_timeout: Open window timeout in ticks
  65  */
  66 struct xwwdt_device {
  67         void __iomem *base;
  68         spinlock_t spinlock; /* spinlock for register handling */
  69         struct watchdog_device xilinx_wwdt_wdd;
  70         unsigned long freq;
  71         u32 close_percent;
  72         u64 closed_timeout;
  73         u64 open_timeout;
  74 };
  75
  76 static int xilinx_wwdt_start(struct watchdog_device *wdd)
  77 {
  78         struct xwwdt_device *xdev = watchdog_get_drvdata(wdd);
  79         struct watchdog_device *xilinx_wwdt_wdd = &xdev->xilinx_wwdt_wdd;
  80         u32 control_status_reg;
  81
  82         spin_lock(&xdev->spinlock);
  83
  84         iowrite32(XWWDT_MWR_MASK, xdev->base + XWWDT_MWR_OFFSET);
  85         iowrite32(~(u32)XWWDT_ESR_WEN_MASK, xdev->base + XWWDT_ESR_OFFSET);
  86         iowrite32((u32)xdev->closed_timeout, xdev->base + XWWDT_FWR_OFFSET);
  87         iowrite32((u32)xdev->open_timeout, xdev->base + XWWDT_SWR_OFFSET);
  88
  89         /* Enable the window watchdog timer */
  90         control_status_reg = ioread32(xdev->base + XWWDT_ESR_OFFSET);
  91         control_status_reg |= XWWDT_ESR_WEN_MASK;
  92         iowrite32(control_status_reg, xdev->base + XWWDT_ESR_OFFSET);
  93
  94         spin_unlock(&xdev->spinlock);
  95
  96         dev_dbg(xilinx_wwdt_wdd->parent, "Watchdog Started!\n");
  97
  98         return 0;
  99 }
 100
 101 static int xilinx_wwdt_keepalive(struct watchdog_device *wdd)
 102 {
 103         struct xwwdt_device *xdev = watchdog_get_drvdata(wdd);
 104         u32 control_status_reg;
 105
 106         spin_lock(&xdev->spinlock);
 107
 108         /* Enable write access control bit for the window watchdog */
 109         iowrite32(XWWDT_MWR_MASK, xdev->base + XWWDT_MWR_OFFSET);
 110
 111         /* Trigger restart kick to watchdog */
 112         control_status_reg = ioread32(xdev->base + XWWDT_ESR_OFFSET);
 113         control_status_reg |= XWWDT_ESR_WSW_MASK;
 114         iowrite32(control_status_reg, xdev->base + XWWDT_ESR_OFFSET);
 115
 116         spin_unlock(&xdev->spinlock);
 117
 118         return 0;
 119 }
 120
 121 static const struct watchdog_info xilinx_wwdt_ident = {
 122         .options = WDIOF_KEEPALIVEPING |
 123                 WDIOF_SETTIMEOUT,
 124         .firmware_version = 1,
 125         .identity = "xlnx_window watchdog",
 126 };
 127
 128 static const struct watchdog_ops xilinx_wwdt_ops = {
 129         .owner = THIS_MODULE,
 130         .start = xilinx_wwdt_start,
 131         .ping = xilinx_wwdt_keepalive,
 132 };
 133
 134 static int xwwdt_probe(struct platform_device *pdev)
 135 {
 136         struct watchdog_device *xilinx_wwdt_wdd;
 137         struct device *dev = &pdev->dev;
 138         struct xwwdt_device *xdev;
 139         u64 max_per_window_ms;
 140         u64 min_per_window_ms;
 141         u64 timeout_count;
 142         struct clk *clk;
 143         u32 timeout_ms;
 144         u64 ms_count;
 145         int ret;
 146
 147         xdev = devm_kzalloc(dev, sizeof(*xdev), GFP_KERNEL);
 148         if (!xdev)
 149                 return -ENOMEM;
 150
 151         xilinx_wwdt_wdd = &xdev->xilinx_wwdt_wdd;
 152         xilinx_wwdt_wdd->info = &xilinx_wwdt_ident;
 153         xilinx_wwdt_wdd->ops = &xilinx_wwdt_ops;
 154         xilinx_wwdt_wdd->parent = dev;
 155
 156         xdev->base = devm_platform_ioremap_resource(pdev, 0);
 157         if (IS_ERR(xdev->base))
 158                 return PTR_ERR(xdev->base);
 159
 160         clk = devm_clk_get_enabled(dev, NULL);
 161         if (IS_ERR(clk))
 162                 return PTR_ERR(clk);
 163
 164         xdev->freq = clk_get_rate(clk);
 165         if (xdev->freq < 1000000)
 166                 return -EINVAL;
 167
 168         xilinx_wwdt_wdd->min_timeout = XWWDT_MIN_TIMEOUT;
 169         xilinx_wwdt_wdd->timeout = XWWDT_DEFAULT_TIMEOUT;
 170         xilinx_wwdt_wdd->max_hw_heartbeat_ms =
 171                 div64_u64(XWWDT_MAX_COUNT_WINDOW_COMBINED, xdev->freq) * 1000;
 172
 173         if (closed_window_percent == 0 || closed_window_percent >= 100)
 174                 xdev->close_percent = XWWDT_CLOSE_WINDOW_PERCENT;
 175         else
 176                 xdev->close_percent = closed_window_percent;
 177
 178         watchdog_init_timeout(xilinx_wwdt_wdd, wwdt_timeout, &pdev->dev);
 179
 180         /* Calculate ticks for 1 milli-second */
 181         ms_count = div_u64(xdev->freq, 1000);
 182         timeout_ms = xilinx_wwdt_wdd->timeout * 1000;
 183         timeout_count = timeout_ms * ms_count;
 184
 185         if (timeout_ms > xilinx_wwdt_wdd->max_hw_heartbeat_ms) {
 186                 /*
 187                  * To avoid ping restrictions until the minimum hardware heartbeat,
 188                  * we will solely rely on the open window and
 189                  * adjust the minimum hardware heartbeat to 0.
 190                  */
 191                 xdev->closed_timeout = 0;
 192                 xdev->open_timeout = XWWDT_MAX_COUNT_WINDOW;
 193                 xilinx_wwdt_wdd->min_hw_heartbeat_ms = 0;
 194                 xilinx_wwdt_wdd->max_hw_heartbeat_ms = xilinx_wwdt_wdd->max_hw_heartbeat_ms / 2;
 195         } else {
 196                 xdev->closed_timeout  = div64_u64(timeout_count * xdev->close_percent, 100);
 197                 xilinx_wwdt_wdd->min_hw_heartbeat_ms =
 198                         div64_u64(timeout_ms * xdev->close_percent, 100);
 199
 200                 if (timeout_ms > xilinx_wwdt_wdd->max_hw_heartbeat_ms / 2) {
 201                         max_per_window_ms = xilinx_wwdt_wdd->max_hw_heartbeat_ms / 2;
 202                         min_per_window_ms = timeout_ms - max_per_window_ms;
 203
 204                         if (xilinx_wwdt_wdd->min_hw_heartbeat_ms > max_per_window_ms) {
 205                                 dev_info(xilinx_wwdt_wdd->parent,
 206                                          "Closed window cannot be set to %d%%. Using maximum supported value.\n",
 207                                         xdev->close_percent);
 208                                 xdev->closed_timeout = max_per_window_ms * ms_count;
 209                                 xilinx_wwdt_wdd->min_hw_heartbeat_ms = max_per_window_ms;
 210                         } else if (xilinx_wwdt_wdd->min_hw_heartbeat_ms < min_per_window_ms) {
 211                                 dev_info(xilinx_wwdt_wdd->parent,
 212                                          "Closed window cannot be set to %d%%. Using minimum supported value.\n",
 213                                         xdev->close_percent);
 214                                 xdev->closed_timeout = min_per_window_ms * ms_count;
 215                                 xilinx_wwdt_wdd->min_hw_heartbeat_ms = min_per_window_ms;
 216                         }
 217                 }
 218                 xdev->open_timeout = timeout_count - xdev->closed_timeout;
 219         }
 220
 221         spin_lock_init(&xdev->spinlock);
 222         watchdog_set_drvdata(xilinx_wwdt_wdd, xdev);
 223         watchdog_set_nowayout(xilinx_wwdt_wdd, 1);
 224
 225         ret = devm_watchdog_register_device(dev, xilinx_wwdt_wdd);
 226         if (ret)
 227                 return ret;
 228
 229         dev_info(dev, "Xilinx window watchdog Timer with timeout %ds\n",
 230                  xilinx_wwdt_wdd->timeout);
 231
 232         return 0;
 233 }
 234
 235 static const struct of_device_id xwwdt_of_match[] = {
 236         { .compatible = "xlnx,versal-wwdt", },
 237         {},
 238 };
 239 MODULE_DEVICE_TABLE(of, xwwdt_of_match);
 240
 241 static struct platform_driver xwwdt_driver = {
 242         .probe = xwwdt_probe,
 243         .driver = {
 244                 .name = "Xilinx window watchdog",
 245                 .of_match_table = xwwdt_of_match,
 246         },
 247 };
 248
 249 module_platform_driver(xwwdt_driver);
 250
 251 MODULE_AUTHOR("Neeli Srinivas <[email protected]>");
 252 MODULE_DESCRIPTION("Xilinx window watchdog driver");
 253 MODULE_LICENSE("GPL");