Re: [PATCH 2/2] watchdog: mediatek: mt7988: add wdt support
From: Guenter Roeck
Date: Fri Nov 10 2023 - 13:29:21 EST
On 11/9/23 16:30, Daniel Golle wrote:
Add support for watchdog and reset generator unit of the MediaTek
MT7988 SoC.
Signed-off-by: Daniel Golle <daniel@xxxxxxxxxxxxxx>
---
drivers/watchdog/mtk_wdt.c | 56 +++++++++++++++++++++++++++++++++++++-
1 file changed, 55 insertions(+), 1 deletion(-)
diff --git a/drivers/watchdog/mtk_wdt.c b/drivers/watchdog/mtk_wdt.c
index b2330b16b497a..b98b8c29735aa 100644
--- a/drivers/watchdog/mtk_wdt.c
+++ b/drivers/watchdog/mtk_wdt.c
@@ -12,6 +12,7 @@
#include <dt-bindings/reset/mt2712-resets.h>
#include <dt-bindings/reset/mediatek,mt6795-resets.h>
#include <dt-bindings/reset/mt7986-resets.h>
+#include <dt-bindings/reset/mediatek,mt7988-resets.h>
#include <dt-bindings/reset/mt8183-resets.h>
#include <dt-bindings/reset/mt8186-resets.h>
#include <dt-bindings/reset/mt8188-resets.h>
@@ -58,6 +59,8 @@
#define WDT_SWSYSRST 0x18U
#define WDT_SWSYS_RST_KEY 0x88000000
+#define WDT_SWSYSRST_EN 0xfc
+
#define DRV_NAME "mtk-wdt"
#define DRV_VERSION "1.0"
@@ -71,44 +74,85 @@ struct mtk_wdt_dev {
struct reset_controller_dev rcdev;
bool disable_wdt_extrst;
bool reset_by_toprgu;
+ bool has_swsysrst_en;
};
struct mtk_wdt_data {
int toprgu_sw_rst_num;
+ bool has_swsysrst_en;
};
static const struct mtk_wdt_data mt2712_data = {
.toprgu_sw_rst_num = MT2712_TOPRGU_SW_RST_NUM,
+ .has_swsysrst_en = false,
Those assignments to false, just like assignments to 0, are unnecessary
for static variables.
};
static const struct mtk_wdt_data mt6795_data = {
.toprgu_sw_rst_num = MT6795_TOPRGU_SW_RST_NUM,
+ .has_swsysrst_en = false,
};
static const struct mtk_wdt_data mt7986_data = {
.toprgu_sw_rst_num = MT7986_TOPRGU_SW_RST_NUM,
+ .has_swsysrst_en = false,
+};
+
+static const struct mtk_wdt_data mt7988_data = {
+ .toprgu_sw_rst_num = MT7988_TOPRGU_SW_RST_NUM,
+ .has_swsysrst_en = true,
};
static const struct mtk_wdt_data mt8183_data = {
.toprgu_sw_rst_num = MT8183_TOPRGU_SW_RST_NUM,
+ .has_swsysrst_en = false,
};
static const struct mtk_wdt_data mt8186_data = {
.toprgu_sw_rst_num = MT8186_TOPRGU_SW_RST_NUM,
+ .has_swsysrst_en = false,
};
static const struct mtk_wdt_data mt8188_data = {
.toprgu_sw_rst_num = MT8188_TOPRGU_SW_RST_NUM,
+ .has_swsysrst_en = false,
};
static const struct mtk_wdt_data mt8192_data = {
.toprgu_sw_rst_num = MT8192_TOPRGU_SW_RST_NUM,
+ .has_swsysrst_en = false,
};
static const struct mtk_wdt_data mt8195_data = {
.toprgu_sw_rst_num = MT8195_TOPRGU_SW_RST_NUM,
+ .has_swsysrst_en = false,
};
+static int toprgu_reset_sw_enable(struct reset_controller_dev *rcdev,
+ unsigned long id, bool enable)
This function name is a bit misleading. It doesn't always
_enable_ something, it updates it based on the enable parameter.
+{
+ unsigned int tmp;
+ unsigned long flags;
+ struct mtk_wdt_dev *data =
+ container_of(rcdev, struct mtk_wdt_dev, rcdev);
+
+ if (!data->has_swsysrst_en)
+ return 0;
+
+ spin_lock_irqsave(&data->lock, flags);
+
+ tmp = readl(data->wdt_base + WDT_SWSYSRST_EN);
+ if (enable)
+ tmp |= BIT(id);
+ else
+ tmp &= ~BIT(id);
+
+ writel(tmp, data->wdt_base + WDT_SWSYSRST_EN);
+
+ spin_unlock_irqrestore(&data->lock, flags);
+
I find this code quite confusing. If it is really necessary to set both
WDT_SWSYSRST_EN and WDT_SWSYSRST together, what is the point of locking twice ?
Why not just handle this in toprgu_reset_update() while the lock is
alread held ? There is a lot of code duplication and inefficiency between
toprgu_reset_sw_enable() and toprgu_reset_update(), and I really don't
see the value of it if WDT_SWSYSRST_EN and WDT_SWSYSRST have to be
written together anyway.
+ return 0;
This function always returns 0. That does not add any value.
+}
+
static int toprgu_reset_update(struct reset_controller_dev *rcdev,
unsigned long id, bool assert)
{
@@ -135,13 +179,20 @@ static int toprgu_reset_update(struct reset_controller_dev *rcdev,
static int toprgu_reset_assert(struct reset_controller_dev *rcdev,
unsigned long id)
{
+ int ret;
+
+ ret = toprgu_reset_sw_enable(rcdev, id, true);
+ if (ret)
+ return ret;
+
I am kind of missing the point of this return value check. I guess it is in line
with the other unnecessary return values / return value checks in this code,
but this really gets a bit out of control. It kind of creates the wrong
assumption or expectation that the called code _may_ return an error,
but in reality it doesn't.
return toprgu_reset_update(rcdev, id, true);
}
static int toprgu_reset_deassert(struct reset_controller_dev *rcdev,
unsigned long id)
{
- return toprgu_reset_update(rcdev, id, false);
+ toprgu_reset_update(rcdev, id, false);
In a way it is commendable that the unnecessary return value handling was dropped,
but that makes the code inconsistent with the reset_assert() function. Also, it is
inconsistent to have the unnecessary return value check in toprgu_reset_assert()
but not here.
+ return toprgu_reset_sw_enable(rcdev, id, false);
}
static int toprgu_reset(struct reset_controller_dev *rcdev,
@@ -406,6 +457,8 @@ static int mtk_wdt_probe(struct platform_device *pdev)
wdt_data->toprgu_sw_rst_num);
if (err)
return err;
+
+ mtk_wdt->has_swsysrst_en = wdt_data->has_swsysrst_en;
This is too late. The reset controller is already registered here,
and the reset controller functions may already have been called.
}
mtk_wdt->disable_wdt_extrst =
Oh well, this and the next property are also called too late because they
affect watchdog operation and the watchdog device has already been registered,
but that is a different bug and not a reason to add even more race conditions
to the driver.
@@ -444,6 +497,7 @@ static const struct of_device_id mtk_wdt_dt_ids[] = {
{ .compatible = "mediatek,mt6589-wdt" },
{ .compatible = "mediatek,mt6795-wdt", .data = &mt6795_data },
{ .compatible = "mediatek,mt7986-wdt", .data = &mt7986_data },
+ { .compatible = "mediatek,mt7988-wdt", .data = &mt7988_data },
{ .compatible = "mediatek,mt8183-wdt", .data = &mt8183_data },
{ .compatible = "mediatek,mt8186-wdt", .data = &mt8186_data },
{ .compatible = "mediatek,mt8188-wdt", .data = &mt8188_data },