[PATCH v3] watchdog: qcom: introduce qcom-wdt driver

Wed Apr 23 09:31:25 CEST 2025

On 23/04/2025 09:02, Sumit Garg wrote:
> On Wed, Apr 23, 2025 at 02:19:39AM +0000, Paul Sajna wrote:
>> From: Casey Connolly <casey.connolly at linaro.org>
>>
>> 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: Casey Connolly <casey.connolly at linaro.org>
>> Signed-off-by: Paul Sajna <hello at paulsajna.com>
>> Co-authored-by: Paul Sajna <hello at paulsajna.com>
>> Tested-by: Paul Sajna <hello at paulsajna.com>
>> ---
>> This patch introduces a simple watchdog driver for Qualcomm devices.
>>
>> Some devices, including one I have been spending a lot of time with,
>> the LG G7 ThinQ (codename judyln, arch sdm845) will reset within 30
>> seconds if the watchdog is not serviced.
>>
>> I have tested this patch from Casey Connolly that is over a year old and has
>> not yet been upstreamed, and it is very useful to me. I can hardly use
>> u-boot on this device without it. I have received Casey's permission to
>> work on upstreaming this patch.
>>
>> This is my first contribution to U-Boot, and I am unfamiliar with
>> mailing list workflows, so please be patient :)
>> ---
>> Changes in v3:
>> - Squash commit 1 and 2
>> - remove duplicated line of code
>> - Link to v2: https://lore.kernel.org/r/20250421-b4-qcom-wdt-v2-0-b2250efa0f39@paulsajna.com
>>
>> Changes in v2:
>> - Add watchdog start
>> - Add watchdog reset
>> - Remove stop from the probe function
>> - Use dev_err instead of printf
>> - Update Casey's name
>> - Add myself as an author
>> -
>> - Link to v1: https://lore.kernel.org/r/20250413-b4-qcom-wdt-v1-1-db42cb93dff8@paulsajna.com
>> ---
>>   configs/qcom_defconfig      |   2 +
>>   drivers/watchdog/Kconfig    |   7 +++
>>   drivers/watchdog/Makefile   |   1 +
>>   drivers/watchdog/qcom-wdt.c | 117 ++++++++++++++++++++++++++++++++++++++++++++
>>   4 files changed, 127 insertions(+)
>>
> 
> Looks reasonable to me, FWIW:
> 
> Acked-by: Sumit Garg <sumit.garg at oss.qualcomm.com>
> 
> -Sumit
> 
>> diff --git a/configs/qcom_defconfig b/configs/qcom_defconfig
>> index 537806450dc4a61d3c617cdd2b0cfb8eab1c343c..0232f6d51c552bd06c8ba72b71edb5cb72fe0706 100644
>> --- a/configs/qcom_defconfig
>> +++ b/configs/qcom_defconfig
>> @@ -144,3 +144,5 @@ 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 1bb67f5035231df9f6ce01adb08d074855393143..808f4e578e28e7812f93b393a7f7d95d9501cdd4 100644
>> --- 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_SANDBOX
>>   	bool "Enable Watchdog Timer support for Sandbox"
>>   	depends on SANDBOX && WDT
>> diff --git a/drivers/watchdog/Makefile b/drivers/watchdog/Makefile
>> index e6bd4c587af6133c405dde6dbada8050debc781c..5eaabd4aba58c815de4165f901aecfba0e0da255 100644
>> --- a/drivers/watchdog/Makefile
>> +++ b/drivers/watchdog/Makefile
>> @@ -54,3 +54,4 @@ 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
>> index 0000000000000000000000000000000000000000..3601ba93774730f78574b2fd74b8c513e7ce22e1
>> --- /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 at linaro.org>
>> + *   Paul Sajna <hello at 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),
>> +};
>>
>> ---
>> base-commit: 0eebdd17888005751cd77cf3794c5292d36f481a
>> change-id: 20250413-b4-qcom-wdt-e7b913fc375e
>>
>> Best regards,
>> -- 
>> Paul Sajna <hello at paulsajna.com>
>>
>>

Reviewed-by: Neil Armstrong <neil.armstrong at linaro.org>