| Message ID | 20190826104636.19324-4-i.mikhaylov@yadro.com |
|---|---|
| State | Superseded, archived |
| Headers | show |
| Series | add dual-boot support | expand |
On Mon, 2019-08-26 at 17:14 -0700, Guenter Roeck wrote: > > +/* > > + * At alternate side 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. > > + * > The above needs to be in the sysfs attribute documentation as well. My apologies but I didn't find any suitable, only watchdog parameters with dtbindings file, where should I put it? Documentation/watchdog/aspeed-wdt- sysfs.rst? > > + * This option can be used with wdt2 (watchdog1) only. > > This implies a specific watchdog numbering which is not guaranteed. > Someone might implement a system with some external watchdog. > > > + */ > > +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 +359,16 @@ 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; > Kind of odd that the attribute only exists if the system booted from the > second flash, but if that is what you want I won't object. Just make sure > that this is explained properly. Perhaps dts configuration option would be better solution for it then? "force- cs0-switch" as example? Also, if it would be an option, dtbindings/wdt file for documentation will be the right place for it. Usage of this at side 0 will not get any good/bad results, it just makes user confused, so I decided to put it only at side 1. It works only for ast2400/2500 board unfortunately, for 2600 there is big difference in switching mechanism. Any other thoughts how to make it better? Thanks.
diff --git a/drivers/watchdog/aspeed_wdt.c b/drivers/watchdog/aspeed_wdt.c index cc71861e033a..bbc42847c0e3 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 +167,57 @@ 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); + uint32_t 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; +} + +/* + * At alternate side 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 +359,16 @@ 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); }
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 accessable 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 <i.mikhaylov@yadro.com> --- drivers/watchdog/aspeed_wdt.c | 62 ++++++++++++++++++++++++++++++++++- 1 file changed, 61 insertions(+), 1 deletion(-)