linux-kernel - Re: [PATCH 07/17] watchdog: qcom: add option for standalone watchdog not in timer block

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Date:	Mon, 28 Mar 2016 11:13:56 -0700
From:	Guenter Roeck <linux@...ck-us.net>
To:	Matthew McClintock <mmcclint@...eaurora.org>
Cc:	andy.gross@...aro.org, linux-arm-msm@...r.kernel.org,
	"qca-upstream.external" <qca-upstream.external@....qualcomm.com>,
	Wim Van Sebroeck <wim@...ana.be>,
	"open list:WATCHDOG DEVICE DRIVERS" <linux-watchdog@...r.kernel.org>,
	open list <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 07/17] watchdog: qcom: add option for standalone watchdog
 not in timer block

On Mon, Mar 28, 2016 at 11:55:28AM -0500, Matthew McClintock wrote:
> 
> > On Mar 25, 2016, at 11:23 AM, Guenter Roeck <linux@...ck-us.net> wrote:
> > 
> >> -#define WDT_RST		0x38
> >> -#define WDT_EN		0x40
> >> -#define WDT_BITE_TIME	0x5C
> >> +enum wdt_reg {
> >> +	WDT_RST,
> >> +	WDT_EN,
> >> +	WDT_BITE_TIME,
> >> +};
> >> +
> >> +static const u32 reg_offset_data_apcs_tmr[] = {
> >> +	[WDT_RST] = 0x38,
> >> +	[WDT_EN] = 0x40,
> >> +	[WDT_BITE_TIME] = 0x5C,
> >> +};
> >> +
> >> +static const u32 reg_offset_data_kpss[] = {
> >> +	[WDT_RST] = 0x4,
> >> +	[WDT_EN] = 0x8,
> > 
> > Does this work ? In the datasheet I have in front of me (APQ8064), the watchdog
> > at this address uses different bits. At address 0x40 (eg GSS_A5_APCS_WDT0_EN),
> 
> 0x40 is acps_tmr, and looks fine.
> 
> > bit 0 is the enable bit, and bit 1 enables interrupts. At address 0x08 (eg
> > LPASS_QDSP6SS_WDOG_UNMASKED_INT_EN), bit 0 enables interrupts and bit 1 is
> > undefined.
> 
> I honestly don’t see anything at 0x8 for either blocks that looks like this. For the new block bit 0 is enabling and bit 1 enabled interrupts.
> 
That is from the APQ8064 datasheet. 

> > Or does "qcom,kpss-standalone" refer to some other watchdog ?
> 
> APQ8064 would be the apcs_tmr block variant which is unchanged. MSM8916 as well as IPQ4019 would use the new kpss variant.
> 
Unfortunately I don't have access to those datasheets.

> I went with block names I found internally here, but I will be the first to admit I am terrible at names. The old block name for APQ was CPU0_ACPS_TMR (where really the watchdog is a subset of a timer block), and on the IPQ4019 it’s called APCS_KPSS_WDT and it’s really just a watchdog block.
> 
> I kept the same driver because the register’s currently in use were compatible. By the way, I tested this on an IPQ806x and IPQ4019 both new and old blocks.
> 

The property name should probably be something like 'qcom,kpss-wdt'
(or 'qcom,kpss-watchdog' ?), possibly in addition to 'qcom,kpss-ipq4019-wdt'
and 'qcom,kpss-msm8916-wdt'.

Guenter