Re: [PATCH v3 7/7] watchdog: dw_wdt: Add DebugFS files

[Guenter Roeck <linux@roeck-us.net>]

On Tue, May 26, 2020 at 06:41:23PM +0300, Serge Semin wrote:
> For the sake of the easier device-driver debug procedure, we added a
> DebugFS file with the controller registers state. It's available only if
> kernel is configured with DebugFS support.
> 
> Signed-off-by: Serge Semin <Sergey.Semin@baikalelectronics.ru>
> Cc: Alexey Malahov <Alexey.Malahov@baikalelectronics.ru>
> Cc: Thomas Bogendoerfer <tsbogend@alpha.franken.de>
> Cc: Arnd Bergmann <arnd@arndb.de>
> Cc: Rob Herring <robh+dt@kernel.org>
> Cc: linux-mips@vger.kernel.org
> Cc: devicetree@vger.kernel.org

Reviewed-by: Guenter Roeck <linux@roeck-us.net>

> ---
> 
> Changelog v2:
> - Rearrange SoBs.
> - Discard timeout/pretimeout/ping/enable DebugFS nodes. Registers state
>   dump node is only left.
> ---
>  drivers/watchdog/dw_wdt.c | 68 +++++++++++++++++++++++++++++++++++++++
>  1 file changed, 68 insertions(+)
> 
> diff --git a/drivers/watchdog/dw_wdt.c b/drivers/watchdog/dw_wdt.c
> index 3cd7c485cd70..012681baaa6d 100644
> --- a/drivers/watchdog/dw_wdt.c
> +++ b/drivers/watchdog/dw_wdt.c
> @@ -28,6 +28,7 @@
>  #include <linux/platform_device.h>
>  #include <linux/reset.h>
>  #include <linux/watchdog.h>
> +#include <linux/debugfs.h>
>  
>  #define WDOG_CONTROL_REG_OFFSET		    0x00
>  #define WDOG_CONTROL_REG_WDT_EN_MASK	    0x01
> @@ -39,8 +40,14 @@
>  #define WDOG_COUNTER_RESTART_KICK_VALUE	    0x76
>  #define WDOG_INTERRUPT_STATUS_REG_OFFSET    0x10
>  #define WDOG_INTERRUPT_CLEAR_REG_OFFSET     0x14
> +#define WDOG_COMP_PARAMS_5_REG_OFFSET       0xe4
> +#define WDOG_COMP_PARAMS_4_REG_OFFSET       0xe8
> +#define WDOG_COMP_PARAMS_3_REG_OFFSET       0xec
> +#define WDOG_COMP_PARAMS_2_REG_OFFSET       0xf0
>  #define WDOG_COMP_PARAMS_1_REG_OFFSET       0xf4
>  #define WDOG_COMP_PARAMS_1_USE_FIX_TOP      BIT(6)
> +#define WDOG_COMP_VERSION_REG_OFFSET        0xf8
> +#define WDOG_COMP_TYPE_REG_OFFSET           0xfc
>  
>  /* There are sixteen TOPs (timeout periods) that can be set in the watchdog. */
>  #define DW_WDT_NUM_TOPS		16
> @@ -85,6 +92,10 @@ struct dw_wdt {
>  	/* Save/restore */
>  	u32			control;
>  	u32			timeout;
> +
> +#ifdef CONFIG_DEBUG_FS
> +	struct dentry		*dbgfs_dir;
> +#endif
>  };
>  
>  #define to_dw_wdt(wdd)	container_of(wdd, struct dw_wdt, wdd)
> @@ -484,6 +495,59 @@ static int dw_wdt_init_timeouts(struct dw_wdt *dw_wdt, struct device *dev)
>  	return 0;
>  }
>  
> +#ifdef CONFIG_DEBUG_FS
> +
> +#define DW_WDT_DBGFS_REG(_name, _off) \
> +{				      \
> +	.name = _name,		      \
> +	.offset = _off		      \
> +}
> +
> +static const struct debugfs_reg32 dw_wdt_dbgfs_regs[] = {
> +	DW_WDT_DBGFS_REG("cr", WDOG_CONTROL_REG_OFFSET),
> +	DW_WDT_DBGFS_REG("torr", WDOG_TIMEOUT_RANGE_REG_OFFSET),
> +	DW_WDT_DBGFS_REG("ccvr", WDOG_CURRENT_COUNT_REG_OFFSET),
> +	DW_WDT_DBGFS_REG("crr", WDOG_COUNTER_RESTART_REG_OFFSET),
> +	DW_WDT_DBGFS_REG("stat", WDOG_INTERRUPT_STATUS_REG_OFFSET),
> +	DW_WDT_DBGFS_REG("param5", WDOG_COMP_PARAMS_5_REG_OFFSET),
> +	DW_WDT_DBGFS_REG("param4", WDOG_COMP_PARAMS_4_REG_OFFSET),
> +	DW_WDT_DBGFS_REG("param3", WDOG_COMP_PARAMS_3_REG_OFFSET),
> +	DW_WDT_DBGFS_REG("param2", WDOG_COMP_PARAMS_2_REG_OFFSET),
> +	DW_WDT_DBGFS_REG("param1", WDOG_COMP_PARAMS_1_REG_OFFSET),
> +	DW_WDT_DBGFS_REG("version", WDOG_COMP_VERSION_REG_OFFSET),
> +	DW_WDT_DBGFS_REG("type", WDOG_COMP_TYPE_REG_OFFSET)
> +};
> +
> +static void dw_wdt_dbgfs_init(struct dw_wdt *dw_wdt)
> +{
> +	struct device *dev = dw_wdt->wdd.parent;
> +	struct debugfs_regset32 *regset;
> +
> +	regset = devm_kzalloc(dev, sizeof(*regset), GFP_KERNEL);
> +	if (!regset)
> +		return;
> +
> +	regset->regs = dw_wdt_dbgfs_regs;
> +	regset->nregs = ARRAY_SIZE(dw_wdt_dbgfs_regs);
> +	regset->base = dw_wdt->regs;
> +
> +	dw_wdt->dbgfs_dir = debugfs_create_dir(dev_name(dev), NULL);
> +
> +	debugfs_create_regset32("registers", 0444, dw_wdt->dbgfs_dir, regset);
> +}
> +
> +static void dw_wdt_dbgfs_clear(struct dw_wdt *dw_wdt)
> +{
> +	debugfs_remove_recursive(dw_wdt->dbgfs_dir);
> +}
> +
> +#else /* !CONFIG_DEBUG_FS */
> +
> +static void dw_wdt_dbgfs_init(struct dw_wdt *dw_wdt) {}
> +static void dw_wdt_dbgfs_clear(struct dw_wdt *dw_wdt) {}
> +
> +#endif /* !CONFIG_DEBUG_FS */
> +
>  static int dw_wdt_drv_probe(struct platform_device *pdev)
>  {
>  	struct device *dev = &pdev->dev;
> @@ -607,6 +671,8 @@ static int dw_wdt_drv_probe(struct platform_device *pdev)
>  	if (ret)
>  		goto out_disable_pclk;
>  
> +	dw_wdt_dbgfs_init(dw_wdt);
> +
>  	return 0;
>  
>  out_disable_pclk:
> @@ -621,6 +687,8 @@ static int dw_wdt_drv_remove(struct platform_device *pdev)
>  {
>  	struct dw_wdt *dw_wdt = platform_get_drvdata(pdev);
>  
> +	dw_wdt_dbgfs_clear(dw_wdt);
> +
>  	watchdog_unregister_device(&dw_wdt->wdd);
>  	reset_control_assert(dw_wdt->rst);
>  	clk_disable_unprepare(dw_wdt->pclk);