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Sat, 31 Aug 2019 08:01:23 -0700 (PDT) Date: Sat, 31 Aug 2019 08:01:22 -0700 From: Guenter Roeck To: Ivan Mikhaylov Subject: Re: [PATCH v4 3/4] watchdog/aspeed: add support for dual boot Message-ID: <20190831150122.GA7207@roeck-us.net> References: <20190828102402.13155-1-i.mikhaylov@yadro.com> <20190828102402.13155-4-i.mikhaylov@yadro.com> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <20190828102402.13155-4-i.mikhaylov@yadro.com> User-Agent: Mutt/1.5.24 (2015-08-30) X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20190831_080125_450097_9D7815D0 X-CRM114-Status: GOOD ( 24.01 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Mark Rutland , devicetree@vger.kernel.org, linux-watchdog@vger.kernel.org, linux-aspeed@lists.ozlabs.org, Andrew Jeffery , openbmc@lists.ozlabs.org, Alexander Amelkin , linux-kernel@vger.kernel.org, Rob Herring , Joel Stanley , Wim Van Sebroeck , linux-arm-kernel@lists.infradead.org Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+infradead-linux-arm-kernel=archiver.kernel.org@lists.infradead.org On Wed, Aug 28, 2019 at 01:24:01PM +0300, Ivan Mikhaylov wrote: > Set WDT_CLEAR_TIMEOUT_AND_BOOT_CODE_SELECTION into WDT_CLEAR_TIMEOUT_STATUS > to clear out boot code source and re-enable access to the primary SPI flash > chip while booted via wdt2 from the alternate chip. > > AST2400 datasheet says: > "In the 2nd flash booting mode, all the address mapping to CS0# would be > re-directed to CS1#. And CS0# is not accessible under this mode. To access > CS0#, firmware should clear the 2nd boot mode register in the WDT2 status > register WDT30.bit[1]." > > Signed-off-by: Ivan Mikhaylov Reviewed-by: Guenter Roeck > --- > drivers/watchdog/aspeed_wdt.c | 65 ++++++++++++++++++++++++++++++++++- > 1 file changed, 64 insertions(+), 1 deletion(-) > > diff --git a/drivers/watchdog/aspeed_wdt.c b/drivers/watchdog/aspeed_wdt.c > index cc71861e033a..125dbd349b00 100644 > --- a/drivers/watchdog/aspeed_wdt.c > +++ b/drivers/watchdog/aspeed_wdt.c > @@ -53,6 +53,8 @@ MODULE_DEVICE_TABLE(of, aspeed_wdt_of_table); > #define WDT_CTRL_ENABLE BIT(0) > #define WDT_TIMEOUT_STATUS 0x10 > #define WDT_TIMEOUT_STATUS_BOOT_SECONDARY BIT(1) > +#define WDT_CLEAR_TIMEOUT_STATUS 0x14 > +#define WDT_CLEAR_TIMEOUT_AND_BOOT_CODE_SELECTION BIT(0) > > /* > * WDT_RESET_WIDTH controls the characteristics of the external pulse (if > @@ -165,6 +167,60 @@ static int aspeed_wdt_restart(struct watchdog_device *wdd, > return 0; > } > > +/* access_cs0 shows if cs0 is accessible, hence the reverted bit */ > +static ssize_t access_cs0_show(struct device *dev, > + struct device_attribute *attr, char *buf) > +{ > + struct aspeed_wdt *wdt = dev_get_drvdata(dev); > + u32 status = readl(wdt->base + WDT_TIMEOUT_STATUS); > + > + return sprintf(buf, "%u\n", > + !(status & WDT_TIMEOUT_STATUS_BOOT_SECONDARY)); > +} > + > +static ssize_t access_cs0_store(struct device *dev, > + struct device_attribute *attr, const char *buf, > + size_t size) > +{ > + struct aspeed_wdt *wdt = dev_get_drvdata(dev); > + unsigned long val; > + > + if (kstrtoul(buf, 10, &val)) > + return -EINVAL; > + > + if (val) > + writel(WDT_CLEAR_TIMEOUT_AND_BOOT_CODE_SELECTION, > + wdt->base + WDT_CLEAR_TIMEOUT_STATUS); > + > + return size; > +} > + > +/* > + * This attribute exists only if the system has booted from the alternate > + * flash with 'alt-boot' option. > + * > + * At alternate flash the 'access_cs0' sysfs node provides: > + * ast2400: a way to get access to the primary SPI flash chip at CS0 > + * after booting from the alternate chip at CS1. > + * ast2500: a way to restore the normal address mapping from > + * (CS0->CS1, CS1->CS0) to (CS0->CS0, CS1->CS1). > + * > + * Clearing the boot code selection and timeout counter also resets to the > + * initial state the chip select line mapping. When the SoC is in normal > + * mapping state (i.e. booted from CS0), clearing those bits does nothing for > + * both versions of the SoC. For alternate boot mode (booted from CS1 due to > + * wdt2 expiration) the behavior differs as described above. > + * > + * This option can be used with wdt2 (watchdog1) only. > + */ > +static DEVICE_ATTR_RW(access_cs0); > + > +static struct attribute *bswitch_attrs[] = { > + &dev_attr_access_cs0.attr, > + NULL > +}; > +ATTRIBUTE_GROUPS(bswitch); > + > static const struct watchdog_ops aspeed_wdt_ops = { > .start = aspeed_wdt_start, > .stop = aspeed_wdt_stop, > @@ -306,9 +362,16 @@ static int aspeed_wdt_probe(struct platform_device *pdev) > } > > status = readl(wdt->base + WDT_TIMEOUT_STATUS); > - if (status & WDT_TIMEOUT_STATUS_BOOT_SECONDARY) > + if (status & WDT_TIMEOUT_STATUS_BOOT_SECONDARY) { > wdt->wdd.bootstatus = WDIOF_CARDRESET; > > + if (of_device_is_compatible(np, "aspeed,ast2400-wdt") || > + of_device_is_compatible(np, "aspeed,ast2500-wdt")) > + wdt->wdd.groups = bswitch_groups; > + } > + > + dev_set_drvdata(dev, wdt); > + > return devm_watchdog_register_device(dev, &wdt->wdd); > } > _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel