On 7/11/23 21:03, Li, Hua Qian wrote:
On Tue, 2023-07-11 at 19:32 -0700, Guenter Roeck wrote:
On 7/11/23 02:17, huaqian.li@xxxxxxxxxxx wrote:
From: Li Hua Qian <huaqian.li@xxxxxxxxxxx>
This patch adds the WDIOF_CARDRESET support for the platform
watchdog
whose hardware does not support this feature, to know if the board
reboot is due to a watchdog reset.
This is done via reserved memory(RAM), which indicates if specific
info saved, triggering the watchdog reset in last boot.
Signed-off-by: Li Hua Qian <huaqian.li@xxxxxxxxxxx>
---
drivers/watchdog/rti_wdt.c | 48
++++++++++++++++++++++++++++++++++++++
1 file changed, 48 insertions(+)
diff --git a/drivers/watchdog/rti_wdt.c
b/drivers/watchdog/rti_wdt.c
index ce8f18e93aa9..77fd6b54137c 100644
--- a/drivers/watchdog/rti_wdt.c
+++ b/drivers/watchdog/rti_wdt.c
@@ -18,6 +18,7 @@
#include <linux/pm_runtime.h>
#include <linux/types.h>
#include <linux/watchdog.h>
+#include <linux/of.h>
#define DEFAULT_HEARTBEAT 60
@@ -52,6 +53,11 @@
#define DWDST BIT(1)
+#define PON_REASON_SOF_NUM 0xBBBBCCCC
+#define PON_REASON_MAGIC_NUM 0xDDDDDDDD
+#define PON_REASON_EOF_NUM 0xCCCCBBBB
+#define PON_REASON_ITEM_BITS 0xFFFFFFFF
+
static int heartbeat = DEFAULT_HEARTBEAT;
/*
@@ -198,6 +204,11 @@ static int rti_wdt_probe(struct
platform_device *pdev)
struct rti_wdt_device *wdt;
struct clk *clk;
u32 last_ping = 0;
+ u32 reserved_mem_size;
+ unsigned long *vaddr;
+ unsigned long paddr;
+ u32 data[3];
+ u32 reg[8];
wdt = devm_kzalloc(dev, sizeof(*wdt), GFP_KERNEL);
if (!wdt)
@@ -284,6 +295,43 @@ static int rti_wdt_probe(struct
platform_device *pdev)
}
}
+ ret = of_property_read_variable_u32_array(pdev-
dev.of_node, "reg", reg,
+ 0, ARRAY_SIZE(reg));
+ if (ret < 0) {
+ dev_err(dev, "cannot read the reg info.\n");
+ goto err_iomap;
+ }
This aborts if the property does not exist, which is unacceptable.
Any such addition must be optional.
Agree, refactor it.
+
+ /*
+ * If reserved memory is defined for watchdog reset cause.
+ * Readout the Power-on(PON) reason and pass to bootstatus.
+ */
+ if (ret == 8) {
+ paddr = reg[5];
+ reserved_mem_size = reg[7];
It seems odd that reserved_mem_size is not checked,
ACK
and that it is even provided
given that it needs to be (at least) 24 bytes, and any other value
does not really
make sense.
I was thinkg to add the reliability, but it seems to be unnecessary and
pointless. Were you suggesting that 8 bytes are enough?
No.
MEMREMAP_WB);
+ if (vaddr == NULL) {
+ dev_err(dev, "Failed to map memory-
region.\n");
+ goto err_iomap;
This returns 8, which would be an odd error return.
ACK,refactor it.
+ }
+
+ data[0] = *vaddr & PON_REASON_ITEM_BITS;
+ data[1] = *(vaddr + 1) & PON_REASON_ITEM_BITS;
+ data[2] = *(vaddr + 2) & PON_REASON_ITEM_BITS;
+
The & seems pointless / wasteful. Why ignore the upper 32 bits of
each location ?
Either make it u32 or make it u64 and use the entire 64 bit. Besides,
vaddr[0..2] would make the code much easier to read.
ACK, refactor it.
+ dev_dbg(dev, "Watchdog: sof = %lX, data = %lX, eof
= %lX\n",
+ data[0], data[1], data[2]);
+
+ if ((data[0] == PON_REASON_SOF_NUM)
+ && (data[1] == PON_REASON_MAGIC_NUM)
+ && (data[1] == PON_REASON_MAGIC_NUM)) {
Unnecessary inner (), and I don't see the point of checking data[1]
twice.
Yeah, a typo happened.
+ dev_info(dev, "Watchdog reset cause
detected.\n");
Unnecessary noise.
ACK,rename dev_info to dev_dbg.
+ wdd->bootstatus |= WDIOF_CARDRESET;
+ }
+ memset(vaddr, 0, reserved_mem_size);
+ memunmap(vaddr);
+ }
And some random data in the property is acceptable ? That is odd,
especially
after mandating the property itself.
Yeah, do you have any suggestions about how to store the watchdog
reset cause?
No, and that is not the point I was trying to make. Your code actively
aborts probe if the "reg" property does not exist at all, but then it
silently ignores if it contains a random number of elements (other
than 8). For example, something like
reg = <0x1234 0x5678>
is silently ignored. If anything, _that_ should return -EINVAL
because it is obviously wrong.
On a higher level, the entire code puzzles me. Obviously there
must be a means for the BIOS or ROMMON to write PON_REASON_SOF_NUM
into some memory area. That means the BIOS/ROMMON must be able
to detect that situation. Why not use the same code to detect this
in the driver without the complexity of passing it from BIOS/ROMMON
to driver in some random memory area ?
Best regards,
Li Hua Qian
+
watchdog_init_timeout(wdd, heartbeat, dev);
ret = watchdog_register_device(wdd);
