| Message ID | 4E007CEB.6040104@arm.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
Marc, On 06/21/2011 06:13 AM, Marc Zyngier wrote: > On 17/06/11 18:25, Rob Herring wrote: >> Also, device tree support for early platform devices would be useful for >> this. > > What about the attached patch? I've used it to boot a VExpress board > with the following DT snippet (and the corresponding support in the > amp_smp_twd driver): > > localtimer@2c000600 { > device_type = "localtimer"; My understanding is device_type is only supposed to be used for devices with real OpenFirmware. You could just add localtimer or timer as a 2nd compatible string. I think localtimer is a bit of a Linux name, so just timer may be better. Rob > compatible = "arm,smp-twd"; > reg = <0x2c000600 0x1000>; > interrupts = <29>; > }; > > Cheers, > > M.
On 21/06/11 13:51, Rob Herring wrote: > Marc, > > On 06/21/2011 06:13 AM, Marc Zyngier wrote: >> On 17/06/11 18:25, Rob Herring wrote: >>> Also, device tree support for early platform devices would be useful for >>> this. >> >> What about the attached patch? I've used it to boot a VExpress board >> with the following DT snippet (and the corresponding support in the >> amp_smp_twd driver): >> >> localtimer@2c000600 { >> device_type = "localtimer"; > > My understanding is device_type is only supposed to be used for devices > with real OpenFirmware. You could just add localtimer or timer as a 2nd > compatible string. I think localtimer is a bit of a Linux name, so just > timer may be better. Using "compatible" would not work. You'd have to add the same compatible string to all drivers, and get drivers probing the wrong device. Any other property we could use instead? As for the "localtimer" string, this is to differentiate the per-cpu timers versus the global timers, and they may need to be probed in a specific order (global first, and then local). The reason for this is that TWD needs to be calibrated, hence the need for a global timer running. Colin's patch could help getting rid of this restriction though. M.
On 06/21/2011 08:02 AM, Marc Zyngier wrote: > On 21/06/11 13:51, Rob Herring wrote: >> Marc, >> >> On 06/21/2011 06:13 AM, Marc Zyngier wrote: >>> On 17/06/11 18:25, Rob Herring wrote: >>>> Also, device tree support for early platform devices would be useful for >>>> this. >>> >>> What about the attached patch? I've used it to boot a VExpress board >>> with the following DT snippet (and the corresponding support in the >>> amp_smp_twd driver): >>> >>> localtimer@2c000600 { >>> device_type = "localtimer"; >> >> My understanding is device_type is only supposed to be used for devices >> with real OpenFirmware. You could just add localtimer or timer as a 2nd >> compatible string. I think localtimer is a bit of a Linux name, so just >> timer may be better. > > Using "compatible" would not work. You'd have to add the same compatible > string to all drivers, and get drivers probing the wrong device. Any > other property we could use instead? No, I'm saying you have a compatible property like this: compatible = "arm,smp-twd", "timer"; You create the early platform device(s) based on matches with "timer", but match the driver based on "arm,smp-twd". > > As for the "localtimer" string, this is to differentiate the per-cpu > timers versus the global timers, and they may need to be probed in a > specific order (global first, and then local). > > The reason for this is that TWD needs to be calibrated, hence the need > for a global timer running. Colin's patch could help getting rid of this > restriction though. Yes, my original patch adding clock api allowed just that. Rob > > M.
From b707a3a80f51c7a5a30b97d33b8b637f318cf886 Mon Sep 17 00:00:00 2001 From: Marc Zyngier <marc.zyngier@arm.com> Date: Tue, 21 Jun 2011 11:40:51 +0100 Subject: [PATCH] dt: early platform devices support Add support for populating early platform devices from the device tree, by walking the tree and adding nodes whose 'device_type' property matches the 'class' string passed as a parameter. This allows devices to be probed long before the whole device insfrastructure is available. Signed-off-by: Marc Zyngier <marc.zyngier@arm.com> --- drivers/of/platform.c | 31 +++++++++++++++++++++++++++++++ include/linux/of_platform.h | 2 ++ 2 files changed, 33 insertions(+), 0 deletions(-) diff --git a/drivers/of/platform.c b/drivers/of/platform.c index 9b785be..976a9ea 100644 --- a/drivers/of/platform.c +++ b/drivers/of/platform.c @@ -326,4 +326,35 @@ int of_platform_populate(struct device_node *root, of_node_put(root); return rc; } + +/** + * of_early_platform_populate() - Populate early platform devices from DT + * @class: string matching the device type to register + * + * This function walks the device tree and register devices whose + * 'device_type' property matches the 'class' parameter. + * + * Returns 0 on success, < 0 on failure. + */ +int of_early_platform_populate(const char *class) +{ + struct platform_device *pdev; + struct device_node *np = NULL; + int id = 0, rc = 0; + + while ((np = of_find_node_by_type(np, class))) { + pdev = kzalloc(sizeof(*pdev), GFP_KERNEL); + if (!pdev) { + of_node_put(np); + rc = -ENOMEM; + break; + } + pdev->name = np->name; + pdev->id = id++; + pdev->dev.of_node = of_node_get(np); + early_platform_add_devices(&pdev, 1); + } + + return rc; +} #endif /* !CONFIG_SPARC */ diff --git a/include/linux/of_platform.h b/include/linux/of_platform.h index 43c723d..fee17f7 100644 --- a/include/linux/of_platform.h +++ b/include/linux/of_platform.h @@ -58,6 +58,8 @@ extern int of_platform_bus_probe(struct device_node *root, extern int of_platform_populate(struct device_node *root, const struct of_device_id *matches, struct device *parent); + +extern int of_early_platform_populate(const char *class); #endif /* !CONFIG_SPARC */ #endif /* CONFIG_OF_DEVICE */ -- 1.7.0.4