watchdog: qcom: introduce qcom-wdt driver

Some Qualcomm device vendors decide to turn the watchdog on in the
bootloader, resulting in the device being reset if it isn't petted every
~30 seconds. Introduce a driver to keep the watchdog happy and prevent this
annoying behaviour.

Signed-off-by: Paul Sajna <hello@paulsajna.com>
Co-authored-by: Paul Sajna <hello@paulsajna.com>
Tested-by: Paul Sajna <hello@paulsajna.com>
Reviewed-by: Stefan Roese <sr@denx.de>
Acked-by: Sumit Garg <sumit.garg@oss.qualcomm.com>
Reviewed-by: Neil Armstrong <neil.armstrong@linaro.org>
Link: https://lore.kernel.org/r/20250422-b4-qcom-wdt-v3-1-730d4d5a858d@paulsajna.com
Signed-off-by: Casey Connolly <casey.connolly@linaro.org>

diff --git a/configs/qcom_defconfig b/configs/qcom_defconfig
index 5eb027ba27b882d3ed10094bf16aeb5cb63c0ef2..e53691df4ca79e137a32b2339656fb1102a7aa8c 100644 (file)
--- a/configs/qcom_defconfig
+++ b/configs/qcom_defconfig
@@ -143,3 +143,5 @@ CONFIG_VIDEO_FONT_16X32=y
 CONFIG_SYS_WHITE_ON_BLACK=y
 CONFIG_NO_FB_CLEAR=y
 CONFIG_VIDEO_SIMPLE=y
+CONFIG_WDT_QCOM=y
+CONFIG_WDT=y

diff --git a/drivers/watchdog/Kconfig b/drivers/watchdog/Kconfig
index a0f2948335f9c3b74b7823f039e578ff4030e97c..38519add771b0abc5b56137873e9d148db49d5c3 100644 (file)
--- a/drivers/watchdog/Kconfig
+++ b/drivers/watchdog/Kconfig
@@ -335,6 +335,13 @@ config WDT_K3_RTI_FW_FILE
 
 endif
 
+config WDT_QCOM
+       bool "Qualcomm watchdog timer support"
+       depends on WDT && ARCH_SNAPDRAGON
+       help
+         Select this to enable Qualcomm watchdog timer, which can be found on
+         some Qualcomm chips.
+
 config WDT_RENESAS
        bool "Renesas watchdog timer support"
        depends on WDT && R8A779F0

diff --git a/drivers/watchdog/Makefile b/drivers/watchdog/Makefile
index c4467d6e126d0c3e119bf8014b302e5b1432f541..d52d17e1c90912e2a248d4d27bf78c9a7a508b46 100644 (file)
--- a/drivers/watchdog/Makefile
+++ b/drivers/watchdog/Makefile
@@ -55,3 +55,4 @@ obj-$(CONFIG_WDT_SUNXI) += sunxi_wdt.o
 obj-$(CONFIG_WDT_TANGIER) += tangier_wdt.o
 obj-$(CONFIG_WDT_XILINX) += xilinx_wwdt.o
 obj-$(CONFIG_WDT_ADI) += adi_wdt.o
+obj-$(CONFIG_WDT_QCOM) += qcom-wdt.o

diff --git a/drivers/watchdog/qcom-wdt.c b/drivers/watchdog/qcom-wdt.c
new file mode 100644 (file)
index 0000000..3601ba9
--- /dev/null
+++ b/drivers/watchdog/qcom-wdt.c
@@ -0,0 +1,117 @@
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * Copyright (c) 2014, The Linux Foundation. All rights reserved.
+ * Copyright (c) Linaro Ltd. 2024
+ *
+ * Authors:
+ *   Casey Connolly <casey.connolly@linaro.org>
+ *   Paul Sajna <hello@paulsajna.com>
+ *
+ * Derived from linux/drivers/watchdog/qcom-wdt.c
+ */
+
+#include <dm.h>
+#include <dm/device_compat.h>
+#include <wdt.h>
+
+#include <asm/io.h>
+
+enum wdt_reg {
+       WDT_RST,
+       WDT_EN,
+       WDT_STS,
+       WDT_BARK_TIME,
+       WDT_BITE_TIME,
+};
+
+struct qcom_wdt_match_data {
+       const u32 *offset;
+};
+
+struct qcom_wdt {
+       void __iomem *base;
+       const u32 *layout;
+};
+
+static const u32 reg_offset_data_kpss[] = {
+       [WDT_RST] = 0x4,
+       [WDT_EN] = 0x8,
+       [WDT_STS] = 0xC,
+       [WDT_BARK_TIME] = 0x10,
+       [WDT_BITE_TIME] = 0x14,
+};
+
+static const struct qcom_wdt_match_data match_data_kpss = {
+       .offset = reg_offset_data_kpss,
+};
+
+static void __iomem *wdt_addr(struct qcom_wdt *wdt, enum wdt_reg reg)
+{
+       return wdt->base + wdt->layout[reg];
+}
+
+int qcom_wdt_start(struct udevice *dev, u64 timeout_ms, ulong flags)
+{
+       struct qcom_wdt *wdt = dev_get_priv(dev);
+
+       writel(0, wdt_addr(wdt, WDT_EN));
+       writel(1, wdt_addr(wdt, WDT_RST));
+       writel(1, wdt_addr(wdt, WDT_EN));
+       if (readl(wdt_addr(wdt, WDT_EN)) != 1) {
+               dev_err(dev, "Failed to enable Qualcomm watchdog!\n");
+               return -EIO;
+       }
+       return 0;
+}
+
+int qcom_wdt_stop(struct udevice *dev)
+{
+       struct qcom_wdt *wdt = dev_get_priv(dev);
+
+       writel(0, wdt_addr(wdt, WDT_EN));
+       if (readl(wdt_addr(wdt, WDT_EN))) {
+               dev_err(dev, "Failed to disable Qualcomm watchdog!\n");
+               return -EIO;
+       }
+
+       return 0;
+}
+
+int qcom_wdt_reset(struct udevice *dev)
+{
+       struct qcom_wdt *wdt = dev_get_priv(dev);
+
+       writel(1, wdt_addr(wdt, WDT_RST));
+       return 0;
+}
+
+static int qcom_wdt_probe(struct udevice *dev)
+{
+       struct qcom_wdt *wdt = dev_get_priv(dev);
+       struct qcom_wdt_match_data *data = (void *)dev_get_driver_data(dev);
+
+       wdt->base = dev_read_addr_ptr(dev);
+       wdt->layout = data->offset;
+
+       return 0;
+}
+
+static const struct wdt_ops qcom_wdt_ops = {
+       .start = qcom_wdt_start,
+       .stop = qcom_wdt_stop,
+       .reset = qcom_wdt_reset,
+};
+
+static const struct udevice_id qcom_wdt_ids[] = {
+       { .compatible = "qcom,kpss-wdt", .data = (ulong)&match_data_kpss },
+       {}
+};
+
+U_BOOT_DRIVER(qcom_wdt) = {
+       .name = "qcom_wdt",
+       .id = UCLASS_WDT,
+       .of_match = qcom_wdt_ids,
+       .ops = &qcom_wdt_ops,
+       .probe = qcom_wdt_probe,
+       .priv_auto = sizeof(struct qcom_wdt),
+};