watchdog: MediaTek: add watchdog driver for MediaTek SoCs

This patch adds a common driver for the Mediatek SoC integrated
watchdog.

Signed-off-by: Ryder Lee <ryder.lee@mediatek.com>
Tested-by: Matthias Brugger <matthias.bgg@gmail.com>
Reviewed-by: Simon Glass <sjg@chromium.org>

diff --git a/drivers/watchdog/Kconfig b/drivers/watchdog/Kconfig
index 4796da0..4a9ebb6 100644 (file)
--- a/drivers/watchdog/Kconfig
+++ b/drivers/watchdog/Kconfig
@@ -103,6 +103,14 @@ config WDT_CDNS
           Select this to enable Cadence watchdog timer, which can be found on some
           Xilinx Microzed Platform.
 
+config WDT_MTK
+       bool "MediaTek watchdog timer support"
+       depends on WDT && ARCH_MEDIATEK
+       help
+         Select this to enable watchdog timer for MediaTek SoCs.
+         The watchdog timer is stopped when initialized.
+         It performs full SoC reset.
+
 config XILINX_TB_WATCHDOG
        bool "Xilinx Axi watchdog timer support"
        depends on WDT

diff --git a/drivers/watchdog/Makefile b/drivers/watchdog/Makefile
index b8f2842..74738ee 100644 (file)
--- a/drivers/watchdog/Makefile
+++ b/drivers/watchdog/Makefile
@@ -24,3 +24,4 @@ obj-$(CONFIG_WDT_ORION) += orion_wdt.o
 obj-$(CONFIG_WDT_CDNS) += cdns_wdt.o
 obj-$(CONFIG_MPC8xx_WATCHDOG) += mpc8xx_wdt.o
 obj-$(CONFIG_WDT_MT7621) += mt7621_wdt.o
+obj-$(CONFIG_WDT_MTK) += mtk_wdt.o

diff --git a/drivers/watchdog/mtk_wdt.c b/drivers/watchdog/mtk_wdt.c
new file mode 100644 (file)
index 0000000..0b50173
--- /dev/null
+++ b/drivers/watchdog/mtk_wdt.c
@@ -0,0 +1,135 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Watchdog driver for MediaTek SoCs
+ *
+ * Copyright (C) 2018 MediaTek Inc.
+ * Author: Ryder Lee <ryder.lee@mediatek.com>
+ */
+
+#include <common.h>
+#include <dm.h>
+#include <wdt.h>
+#include <asm/io.h>
+
+#define MTK_WDT_MODE                   0x00
+#define MTK_WDT_LENGTH                 0x04
+#define MTK_WDT_RESTART                        0x08
+#define MTK_WDT_STATUS                 0x0c
+#define MTK_WDT_INTERVAL               0x10
+#define MTK_WDT_SWRST                  0x14
+#define MTK_WDT_REQ_MODE               0x30
+#define MTK_WDT_DEBUG_CTL              0x40
+
+#define WDT_MODE_KEY                   (0x22 << 24)
+#define WDT_MODE_EN                    BIT(0)
+#define WDT_MODE_EXTPOL                        BIT(1)
+#define WDT_MODE_EXTEN                 BIT(2)
+#define WDT_MODE_IRQ_EN                        BIT(3)
+#define WDT_MODE_DUAL_EN               BIT(6)
+
+#define WDT_LENGTH_KEY                 0x8
+#define WDT_LENGTH_TIMEOUT(n)          ((n) << 5)
+
+#define WDT_RESTART_KEY                        0x1971
+#define WDT_SWRST_KEY                  0x1209
+
+struct mtk_wdt_priv {
+       void __iomem *base;
+};
+
+static int mtk_wdt_reset(struct udevice *dev)
+{
+       struct mtk_wdt_priv *priv = dev_get_priv(dev);
+
+       /* Reload watchdog duration */
+       writel(WDT_RESTART_KEY, priv->base + MTK_WDT_RESTART);
+
+       return 0;
+}
+
+static int mtk_wdt_stop(struct udevice *dev)
+{
+       struct mtk_wdt_priv *priv = dev_get_priv(dev);
+
+       clrsetbits_le32(priv->base + MTK_WDT_MODE, WDT_MODE_EN, WDT_MODE_KEY);
+
+       return 0;
+}
+
+static int mtk_wdt_expire_now(struct udevice *dev, ulong flags)
+{
+       struct mtk_wdt_priv *priv = dev_get_priv(dev);
+
+       /* Kick watchdog to prevent counter == 0 */
+       writel(WDT_RESTART_KEY, priv->base + MTK_WDT_RESTART);
+
+       /* Reset */
+       writel(WDT_SWRST_KEY, priv->base + MTK_WDT_SWRST);
+       hang();
+
+       return 0;
+}
+
+static void mtk_wdt_set_timeout(struct udevice *dev, unsigned int timeout)
+{
+       struct mtk_wdt_priv *priv = dev_get_priv(dev);
+
+       /*
+        * One bit is the value of 512 ticks
+        * The clock has 32 KHz
+        */
+       timeout = WDT_LENGTH_TIMEOUT(timeout << 6) | WDT_LENGTH_KEY;
+       writel(timeout, priv->base + MTK_WDT_LENGTH);
+
+       mtk_wdt_reset(dev);
+}
+
+static int mtk_wdt_start(struct udevice *dev, u64 timeout, ulong flags)
+{
+       struct mtk_wdt_priv *priv = dev_get_priv(dev);
+
+       mtk_wdt_set_timeout(dev, timeout);
+
+       /* Enable watchdog reset signal */
+       setbits_le32(priv->base + MTK_WDT_MODE,
+                    WDT_MODE_EN | WDT_MODE_KEY | WDT_MODE_EXTEN);
+
+       return 0;
+}
+
+static int mtk_wdt_probe(struct udevice *dev)
+{
+       struct mtk_wdt_priv *priv = dev_get_priv(dev);
+
+       priv->base = dev_read_addr_ptr(dev);
+       if (!priv->base)
+               return -ENOENT;
+
+       /* Clear status */
+       clrsetbits_le32(priv->base + MTK_WDT_MODE,
+                       WDT_MODE_IRQ_EN | WDT_MODE_EXTPOL, WDT_MODE_KEY);
+
+       return mtk_wdt_stop(dev);
+}
+
+static const struct wdt_ops mtk_wdt_ops = {
+       .start = mtk_wdt_start,
+       .reset = mtk_wdt_reset,
+       .stop = mtk_wdt_stop,
+       .expire_now = mtk_wdt_expire_now,
+};
+
+static const struct udevice_id mtk_wdt_ids[] = {
+       { .compatible = "mediatek,wdt"},
+       {}
+};
+
+U_BOOT_DRIVER(mtk_wdt) = {
+       .name = "mtk_wdt",
+       .id = UCLASS_WDT,
+       .of_match = mtk_wdt_ids,
+       .priv_auto_alloc_size = sizeof(struct mtk_wdt_priv),
+       .probe = mtk_wdt_probe,
+       .ops = &mtk_wdt_ops,
+       .flags = DM_FLAG_PRE_RELOC,
+};