| Message ID | 20140122180100.GE27273@localhost |
|---|---|
| State | New |
| Headers | show |
On Wed, Jan 22, 2014 at 03:01:01PM -0300, Ezequiel Garcia wrote: > On Wed, Jan 22, 2014 at 01:21:36PM -0300, Ezequiel Garcia wrote: > > > I don't see a good way out that would preserve backwards compatibility, > > > other than hardcoding the physical address in the driver, which seems > > > just as bad as breaking compatibility. That said, it is always the > > > same constant (0xf1000000 + 0x20000 + 0x0108) on Dove, Kirkwood and > > > Orion5x (not on mv78xx0, but that doesn't use the wdt), so hardcoding > > > a fallback would technically work, but we should print a fat warning at > > > boot time if we actually fall back to that. > > > > > > > Yes, I was thinking just about this. Namely: > > > [..] > > How about something like this? I liked Arnd's idea to use an offset from the first register. With the mbus driver we can now actually change the 0xF1.. prefix via the DT. > + dev_warn(&pdev->dev, "falling back to harcoded RSTOUT reg 0x%x\n", > + ORION_RSTOUT_MASK); Maybe: dev_warn(&pdev->dev, FW_BUG "falling back to harcoded RSTOUT reg 0x%x\n", ? > @@ -139,10 +166,7 @@ static int orion_wdt_probe(struct platform_device *pdev) > if (!wdt_reg) > return -ENOMEM; > > - res = platform_get_resource(pdev, IORESOURCE_MEM, 1); > - if (!res) > - return -ENODEV; > - wdt_rstout = devm_ioremap(&pdev->dev, res->start, resource_size(res)); > + wdt_rstout = try_compat_rstout_ioremap(pdev); > if (!wdt_rstout) > return -ENOMEM; ENOMEM is probably not the right errno? Is there a standard errno for malformed DT? Jason
On Wednesday 22 January 2014 11:14:09 Jason Gunthorpe wrote: > On Wed, Jan 22, 2014 at 03:01:01PM -0300, Ezequiel Garcia wrote: > > On Wed, Jan 22, 2014 at 01:21:36PM -0300, Ezequiel Garcia wrote: > > > > I don't see a good way out that would preserve backwards compatibility, > > > > other than hardcoding the physical address in the driver, which seems > > > > just as bad as breaking compatibility. That said, it is always the > > > > same constant (0xf1000000 + 0x20000 + 0x0108) on Dove, Kirkwood and > > > > Orion5x (not on mv78xx0, but that doesn't use the wdt), so hardcoding > > > > a fallback would technically work, but we should print a fat warning at > > > > boot time if we actually fall back to that. > > > > > > > > > > Yes, I was thinking just about this. Namely: > > > > > [..] > > > > How about something like this? > > I liked Arnd's idea to use an offset from the first register. With the > mbus driver we can now actually change the 0xF1.. prefix via the DT. That wasn't actually my idea, but it does sound reasonable. > > + dev_warn(&pdev->dev, "falling back to harcoded RSTOUT reg 0x%x\n", > > + ORION_RSTOUT_MASK); > > Maybe: > dev_warn(&pdev->dev, FW_BUG "falling back to harcoded RSTOUT reg 0x%x\n", I was thinking of WARN_ON(), i.e. something that users will actually notice ;-) > > @@ -139,10 +166,7 @@ static int orion_wdt_probe(struct platform_device *pdev) > > if (!wdt_reg) > > return -ENOMEM; > > > > - res = platform_get_resource(pdev, IORESOURCE_MEM, 1); > > - if (!res) > > - return -ENODEV; > > - wdt_rstout = devm_ioremap(&pdev->dev, res->start, resource_size(res)); > > + wdt_rstout = try_compat_rstout_ioremap(pdev); > > if (!wdt_rstout) > > return -ENOMEM; > > ENOMEM is probably not the right errno? Is there a standard errno for > malformed DT? I don't think so. I'd probably use ENODEV, but it's not ideal. Arnd
On Wed, Jan 22, 2014 at 11:14:09AM -0700, Jason Gunthorpe wrote: > On Wed, Jan 22, 2014 at 03:01:01PM -0300, Ezequiel Garcia wrote: > > On Wed, Jan 22, 2014 at 01:21:36PM -0300, Ezequiel Garcia wrote: > > > > I don't see a good way out that would preserve backwards compatibility, > > > > other than hardcoding the physical address in the driver, which seems > > > > just as bad as breaking compatibility. That said, it is always the > > > > same constant (0xf1000000 + 0x20000 + 0x0108) on Dove, Kirkwood and > > > > Orion5x (not on mv78xx0, but that doesn't use the wdt), so hardcoding > > > > a fallback would technically work, but we should print a fat warning at > > > > boot time if we actually fall back to that. > > > > > > > > > > Yes, I was thinking just about this. Namely: > > > > > [..] > > > > How about something like this? > > I liked Arnd's idea to use an offset from the first register. With the > mbus driver we can now actually change the 0xF1.. prefix via the DT. > Good idea. Maybe extracting the base address from the timer control register: wdt_reg & 0xff000000 ?
diff --git a/drivers/watchdog/orion_wdt.c b/drivers/watchdog/orion_wdt.c index a861b88..0014d23 100644 --- a/drivers/watchdog/orion_wdt.c +++ b/drivers/watchdog/orion_wdt.c @@ -26,6 +26,9 @@ #include <linux/of.h> #include <mach/bridge-regs.h> +/* RSTOUT mask register physical address for Orion5x, Kirkwood and Dove */ +#define ORION_RSTOUT_MASK 0xf1020108 + /* * Watchdog timer block registers. */ @@ -119,6 +122,30 @@ static irqreturn_t orion_wdt_irq(int irq, void *devid) return IRQ_HANDLED; } +/* + * The original devicetree binding for this driver specified only + * one memory resource, so in order to keep DT backwards compatibility + * we try to fallback to a hardcoded register address, if the resource + * is missing from the devicetree. + */ +static void __iomem * try_compat_rstout_ioremap(struct platform_device *pdev) +{ + struct resource *res; + + res = platform_get_resource(pdev, IORESOURCE_MEM, 1); + if (res) + return devm_ioremap(&pdev->dev, res->start, + resource_size(res)); + + /* This workaround works only for "orion-wdt", DT-enabled */ + if (!of_device_is_compatible(pdev->dev.of_node, "marvell,orion-wdt")) + return NULL; + + dev_warn(&pdev->dev, "falling back to harcoded RSTOUT reg 0x%x\n", + ORION_RSTOUT_MASK); + return devm_ioremap(&pdev->dev, ORION_RSTOUT_MASK, 0x4); +} + static int orion_wdt_probe(struct platform_device *pdev) { struct resource *res; @@ -139,10 +166,7 @@ static int orion_wdt_probe(struct platform_device *pdev) if (!wdt_reg) return -ENOMEM; - res = platform_get_resource(pdev, IORESOURCE_MEM, 1); - if (!res) - return -ENODEV; - wdt_rstout = devm_ioremap(&pdev->dev, res->start, resource_size(res)); + wdt_rstout = try_compat_rstout_ioremap(pdev); if (!wdt_rstout) return -ENOMEM;