target/linux/ixp4xx/patches-6.1/0007-watchdog-ixp4xx-Make-sure-restart-always-works.patch

   1 From b09e5ea32e099821b1cddc1e26e625ad994ba11e Mon Sep 17 00:00:00 2001
   2 From: Linus Walleij <linus.walleij@linaro.org>
   3 Date: Sun, 24 Sep 2023 21:20:24 +0200
   4 Subject: [PATCH] watchdog: ixp4xx: Make sure restart always works
   5
   6 The IXP4xx watchdog in early "A0" silicon is unreliable and
   7 cannot be registered, however for some systems such as the
   8 USRobotics USR8200 the watchdog is the only restart option,
   9 so implement a "dummy" watchdog that can only support restart
  10 in this case.
  11
  12 Fixes: 1aea522809e6 ("watchdog: ixp4xx: Implement restart")
  13 Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
  14 ---
  15 Other solutions like implementing a pure restart notifier
  16 callback catch in the driver is possible, but this method
  17 will minimize the amount of code and reuse infrastructure
  18 in the core.
  19 ---
  20  drivers/watchdog/ixp4xx_wdt.c | 28 +++++++++++++++++++++++++---
  21  1 file changed, 25 insertions(+), 3 deletions(-)
  22
  23 --- a/drivers/watchdog/ixp4xx_wdt.c
  24 +++ b/drivers/watchdog/ixp4xx_wdt.c
  25 @@ -105,6 +105,25 @@ static const struct watchdog_ops ixp4xx_
  26         .owner = THIS_MODULE,
  27  };
  28
  29 +/*
  30 + * The A0 version of the IXP422 had a bug in the watchdog making
  31 + * is useless, but we still need to use it to restart the system
  32 + * as it is the only way, so in this special case we register a
  33 + * "dummy" watchdog that doesn't really work, but will support
  34 + * the restart operation.
  35 + */
  36 +static int ixp4xx_wdt_dummy(struct watchdog_device *wdd)
  37 +{
  38 +       return 0;
  39 +}
  40 +
  41 +static const struct watchdog_ops ixp4xx_wdt_restart_only_ops = {
  42 +       .start = ixp4xx_wdt_dummy,
  43 +       .stop = ixp4xx_wdt_dummy,
  44 +       .restart = ixp4xx_wdt_restart,
  45 +       .owner = THIS_MODULE,
  46 +};
  47 +
  48  static const struct watchdog_info ixp4xx_wdt_info = {
  49         .options = WDIOF_KEEPALIVEPING
  50                 | WDIOF_MAGICCLOSE
  51 @@ -120,14 +139,17 @@ static void ixp4xx_clock_action(void *d)
  52
  53  static int ixp4xx_wdt_probe(struct platform_device *pdev)
  54  {
  55 +       static const struct watchdog_ops *iwdt_ops;
  56         struct device *dev = &pdev->dev;
  57         struct ixp4xx_wdt *iwdt;
  58         struct clk *clk;
  59         int ret;
  60
  61         if (!(read_cpuid_id() & 0xf) && !cpu_is_ixp46x()) {
  62 -               dev_err(dev, "Rev. A0 IXP42x CPU detected - watchdog disabled\n");
  63 -               return -ENODEV;
  64 +               dev_err(dev, "Rev. A0 IXP42x CPU detected - only restart supported\n");
  65 +               iwdt_ops = &ixp4xx_wdt_restart_only_ops;
  66 +       } else {
  67 +               iwdt_ops = &ixp4xx_wdt_ops;
  68         }
  69
  70         iwdt = devm_kzalloc(dev, sizeof(*iwdt), GFP_KERNEL);
  71 @@ -153,7 +175,7 @@ static int ixp4xx_wdt_probe(struct platf
  72                 iwdt->rate = IXP4XX_TIMER_FREQ;
  73
  74         iwdt->wdd.info = &ixp4xx_wdt_info;
  75 -       iwdt->wdd.ops = &ixp4xx_wdt_ops;
  76 +       iwdt->wdd.ops = iwdt_ops;
  77         iwdt->wdd.min_timeout = 1;
  78         iwdt->wdd.max_timeout = U32_MAX / iwdt->rate;
  79         iwdt->wdd.parent = dev;