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 - 2023, 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 static int wwdt_timeout;
  40 static int closed_window_percent;
  41
  42 module_param(wwdt_timeout, int, 0);
  43 MODULE_PARM_DESC(wwdt_timeout,
  44                  "Watchdog time in seconds. (default="
  45                  __MODULE_STRING(XWWDT_DEFAULT_TIMEOUT) ")");
  46 module_param(closed_window_percent, int, 0);
  47 MODULE_PARM_DESC(closed_window_percent,
  48                  "Watchdog closed window percentage. (default="
  49                  __MODULE_STRING(XWWDT_CLOSE_WINDOW_PERCENT) ")");
  50 /**
  51  * struct xwwdt_device - Watchdog device structure
  52  * @base: base io address of WDT device
  53  * @spinlock: spinlock for IO register access
  54  * @xilinx_wwdt_wdd: watchdog device structure
  55  * @freq: source clock frequency of WWDT
  56  * @close_percent: Closed window percent
  57  */
  58 struct xwwdt_device {
  59         void __iomem *base;
  60         spinlock_t spinlock; /* spinlock for register handling */
  61         struct watchdog_device xilinx_wwdt_wdd;
  62         unsigned long freq;
  63         u32 close_percent;
  64 };
  65
  66 static int xilinx_wwdt_start(struct watchdog_device *wdd)
  67 {
  68         struct xwwdt_device *xdev = watchdog_get_drvdata(wdd);
  69         struct watchdog_device *xilinx_wwdt_wdd = &xdev->xilinx_wwdt_wdd;
  70         u64 time_out, closed_timeout, open_timeout;
  71         u32 control_status_reg;
  72
  73         /* Calculate timeout count */
  74         time_out = xdev->freq * wdd->timeout;
  75         closed_timeout = div_u64(time_out * xdev->close_percent, 100);
  76         open_timeout = time_out - closed_timeout;
  77         wdd->min_hw_heartbeat_ms = xdev->close_percent * 10 * wdd->timeout;
  78
  79         spin_lock(&xdev->spinlock);
  80
  81         iowrite32(XWWDT_MWR_MASK, xdev->base + XWWDT_MWR_OFFSET);
  82         iowrite32(~(u32)XWWDT_ESR_WEN_MASK, xdev->base + XWWDT_ESR_OFFSET);
  83         iowrite32((u32)closed_timeout, xdev->base + XWWDT_FWR_OFFSET);
  84         iowrite32((u32)open_timeout, xdev->base + XWWDT_SWR_OFFSET);
  85
  86         /* Enable the window watchdog timer */
  87         control_status_reg = ioread32(xdev->base + XWWDT_ESR_OFFSET);
  88         control_status_reg |= XWWDT_ESR_WEN_MASK;
  89         iowrite32(control_status_reg, xdev->base + XWWDT_ESR_OFFSET);
  90
  91         spin_unlock(&xdev->spinlock);
  92
  93         dev_dbg(xilinx_wwdt_wdd->parent, "Watchdog Started!\n");
  94
  95         return 0;
  96 }
  97
  98 static int xilinx_wwdt_keepalive(struct watchdog_device *wdd)
  99 {
 100         struct xwwdt_device *xdev = watchdog_get_drvdata(wdd);
 101         u32 control_status_reg;
 102
 103         spin_lock(&xdev->spinlock);
 104
 105         /* Enable write access control bit for the window watchdog */
 106         iowrite32(XWWDT_MWR_MASK, xdev->base + XWWDT_MWR_OFFSET);
 107
 108         /* Trigger restart kick to watchdog */
 109         control_status_reg = ioread32(xdev->base + XWWDT_ESR_OFFSET);
 110         control_status_reg |= XWWDT_ESR_WSW_MASK;
 111         iowrite32(control_status_reg, xdev->base + XWWDT_ESR_OFFSET);
 112
 113         spin_unlock(&xdev->spinlock);
 114
 115         return 0;
 116 }
 117
 118 static const struct watchdog_info xilinx_wwdt_ident = {
 119         .options = WDIOF_KEEPALIVEPING |
 120                 WDIOF_SETTIMEOUT,
 121         .firmware_version = 1,
 122         .identity = "xlnx_window watchdog",
 123 };
 124
 125 static const struct watchdog_ops xilinx_wwdt_ops = {
 126         .owner = THIS_MODULE,
 127         .start = xilinx_wwdt_start,
 128         .ping = xilinx_wwdt_keepalive,
 129 };
 130
 131 static int xwwdt_probe(struct platform_device *pdev)
 132 {
 133         struct watchdog_device *xilinx_wwdt_wdd;
 134         struct device *dev = &pdev->dev;
 135         struct xwwdt_device *xdev;
 136         struct clk *clk;
 137         int ret;
 138
 139         xdev = devm_kzalloc(dev, sizeof(*xdev), GFP_KERNEL);
 140         if (!xdev)
 141                 return -ENOMEM;
 142
 143         xilinx_wwdt_wdd = &xdev->xilinx_wwdt_wdd;
 144         xilinx_wwdt_wdd->info = &xilinx_wwdt_ident;
 145         xilinx_wwdt_wdd->ops = &xilinx_wwdt_ops;
 146         xilinx_wwdt_wdd->parent = dev;
 147
 148         xdev->base = devm_platform_ioremap_resource(pdev, 0);
 149         if (IS_ERR(xdev->base))
 150                 return PTR_ERR(xdev->base);
 151
 152         clk = devm_clk_get_enabled(dev, NULL);
 153         if (IS_ERR(clk))
 154                 return PTR_ERR(clk);
 155
 156         xdev->freq = clk_get_rate(clk);
 157         if (!xdev->freq)
 158                 return -EINVAL;
 159
 160         xilinx_wwdt_wdd->min_timeout = XWWDT_MIN_TIMEOUT;
 161         xilinx_wwdt_wdd->timeout = XWWDT_DEFAULT_TIMEOUT;
 162         xilinx_wwdt_wdd->max_hw_heartbeat_ms = 1000 * xilinx_wwdt_wdd->timeout;
 163
 164         if (closed_window_percent == 0 || closed_window_percent >= 100)
 165                 xdev->close_percent = XWWDT_CLOSE_WINDOW_PERCENT;
 166         else
 167                 xdev->close_percent = closed_window_percent;
 168
 169         watchdog_init_timeout(xilinx_wwdt_wdd, wwdt_timeout, &pdev->dev);
 170         spin_lock_init(&xdev->spinlock);
 171         watchdog_set_drvdata(xilinx_wwdt_wdd, xdev);
 172         watchdog_set_nowayout(xilinx_wwdt_wdd, 1);
 173
 174         ret = devm_watchdog_register_device(dev, xilinx_wwdt_wdd);
 175         if (ret)
 176                 return ret;
 177
 178         dev_info(dev, "Xilinx window watchdog Timer with timeout %ds\n",
 179                  xilinx_wwdt_wdd->timeout);
 180
 181         return 0;
 182 }
 183
 184 static const struct of_device_id xwwdt_of_match[] = {
 185         { .compatible = "xlnx,versal-wwdt", },
 186         {},
 187 };
 188 MODULE_DEVICE_TABLE(of, xwwdt_of_match);
 189
 190 static struct platform_driver xwwdt_driver = {
 191         .probe = xwwdt_probe,
 192         .driver = {
 193                 .name = "Xilinx window watchdog",
 194                 .of_match_table = xwwdt_of_match,
 195         },
 196 };
 197
 198 module_platform_driver(xwwdt_driver);
 199
 200 MODULE_AUTHOR("Neeli Srinivas <srinivas.neeli@amd.com>");
 201 MODULE_DESCRIPTION("Xilinx window watchdog driver");
 202 MODULE_LICENSE("GPL");