On 7/14/2012 3:56 AM, Jon Hunter wrote: > OMAP3 devices may or may not have security features enabled. Security enabled > devices are known as high-secure (HS) and devices without security are known as > general purpose (GP). > > For OMAP3 devices there are 12 general purpose timers available. On secure > devices the 12th timer is reserved for secure usage and so cannot be used by > the kernel, where as for a GP device it is available. We can detect the OMAP > device type, secure or GP, at runtime via an on-chip register. Today, when not > using DT, we do not register the 12th timer as a linux device if the device is > secure. > > When using device tree, device tree is going to register all the timer devices > it finds in the device tree blob. To prevent device tree from registering 12th > timer on a secure OMAP3 device we can add a status property to the timer > binding with the value "disabled" at boot time. Note that timer 12 on a OMAP3 > device has a property "ti,timer-secure" to indicate that it will not be > available on a secure device and so for secure OMAP3 devices, we search for > timers with this property and then disable them. Using the prom_add_property() > function to dynamically add a property was a recommended approach suggested by > Rob Herring [1]. > > I have tested this on an OMAP3 GP device and faking it to pretend to be a > secure device to ensure that any timers marked with "ti,timer-secure" are not > registered on boot. I have also made sure that all timers are registered as > expected on a GP device by default. > > [1] http://comments.gmane.org/gmane.linux.ports.arm.omap/79203 > > Signed-off-by: Jon Hunter <jon-hunter@xxxxxx> > --- > arch/arm/mach-omap2/board-generic.c | 1 + > arch/arm/mach-omap2/common.h | 1 + > arch/arm/mach-omap2/timer.c | 36 +++++++++++++++++++++++++++++++++++ > 3 files changed, 38 insertions(+) > > diff --git a/arch/arm/mach-omap2/board-generic.c b/arch/arm/mach-omap2/board-generic.c > index 6f93a20..20124d7 100644 > --- a/arch/arm/mach-omap2/board-generic.c > +++ b/arch/arm/mach-omap2/board-generic.c > @@ -40,6 +40,7 @@ static struct of_device_id omap_dt_match_table[] __initdata = { > static void __init omap_generic_init(void) > { > omap_sdrc_init(NULL, NULL); > + omap_dmtimer_init(); > > of_platform_populate(NULL, omap_dt_match_table, NULL, NULL); > } > diff --git a/arch/arm/mach-omap2/common.h b/arch/arm/mach-omap2/common.h > index 1f65b18..d6a4875 100644 > --- a/arch/arm/mach-omap2/common.h > +++ b/arch/arm/mach-omap2/common.h > @@ -326,6 +326,7 @@ extern void omap_sdrc_init(struct omap_sdrc_params *sdrc_cs0, > struct omap_sdrc_params *sdrc_cs1); > struct omap2_hsmmc_info; > extern int omap4_twl6030_hsmmc_init(struct omap2_hsmmc_info *controllers); > +extern void omap_dmtimer_init(void); > > #endif /* __ASSEMBLER__ */ > #endif /* __ARCH_ARM_MACH_OMAP2PLUS_COMMON_H */ > diff --git a/arch/arm/mach-omap2/timer.c b/arch/arm/mach-omap2/timer.c > index 13d20c8..e3b9931 100644 > --- a/arch/arm/mach-omap2/timer.c > +++ b/arch/arm/mach-omap2/timer.c > @@ -36,6 +36,7 @@ > #include <linux/clocksource.h> > #include <linux/clockchips.h> > #include <linux/slab.h> > +#include <linux/of.h> > > #include <asm/mach/time.h> > #include <plat/dmtimer.h> > @@ -482,6 +483,41 @@ static int __init omap2_dm_timer_init(void) > } > arch_initcall(omap2_dm_timer_init); > > +static struct property timer_disabled = { > + .name = "status", > + .length = sizeof("disabled"), > + .value = "disabled", > +}; > + > +static struct of_device_id omap3_timer_match[] __initdata = { > + { .compatible = "ti,omap3-timer", }, > + { } > +}; > + > +/** > + * omap_dmtimer_init - initialisation function when device tree is used > + * > + * For secure OMAP3 devices, timers with device type "timer-secure" cannot > + * be used by the kernel as they are reserved. Therefore, to prevent the > + * kernel registering these devices remove them dynamically from the device > + * tree on boot. > + */ > +void __init omap_dmtimer_init(void) > +{ > + struct device_node *np; > + > + if (!cpu_is_omap34xx()) > + return; > + Sorry for responding so late, but why only omap34xx check here? Isn't this applicable to all omap & non-omap devices? Thanks, Vaibhav > + /* If we are a secure device, remove any secure timer nodes */ > + if ((omap_type() != OMAP2_DEVICE_TYPE_GP)) { > + for_each_matching_node(np, omap3_timer_match) { > + if (of_get_property(np, "ti,timer-secure", NULL)) > + prom_add_property(np, &timer_disabled); > + } > + } > +} > + > /** > * omap2_override_clocksource - clocksource override with user configuration > * > -- To unsubscribe from this list: send the line "unsubscribe linux-omap" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
