watchdog: dw_wdt: Add DebugFS files

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>
Reviewed-by: Guenter Roeck <linux@roeck-us.net>
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
Link: https://lore.kernel.org/r/20200530073557.22661-8-Sergey.Semin@baikalelectronics.ru
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Wim Van Sebroeck <wim@linux-watchdog.org>

diff --git a/drivers/watchdog/dw_wdt.c b/drivers/watchdog/dw_wdt.c
index 7a17192..4fec2c6 100644 (file)
--- 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);