| Message ID | 1354795719-5578-2-git-send-email-hechtb+renesas@gmail.com (mailing list archive) |
|---|---|
| State | Superseded |
| Commit | 20aa11358d52e1a3fc037d601ffe704e6f55c5fb |
| Headers | show |
On Thu, Dec 6, 2012 at 9:08 PM, Bastian Hecht <hechtb@gmail.com> wrote: > From: Bastian Hecht <hechtb@gmail.com> > > Add the capability to add and remove CPUs on the fly. > The Cortex-A9 offers the possibility to take single cores out of the > MP Core. We add this capabilty taking care that caches are kept > coherent. For the actual shutdown via a WFI instruction, a code snippet > from the omap2 code tree is copied. Thanks for that! For verifying the > shutdown we rely on the internal SH73A0 Power Status Register > PSTR. > > Signed-off-by: Bastian Hecht <hechtb+renesas@gmail.com> Acked-by: Magnus Damm <damm@opensource.se> -- To unsubscribe from this list: send the line "unsubscribe linux-sh" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
On 12/06/2012 06:08 AM, Bastian Hecht wrote: > From: Bastian Hecht <hechtb@gmail.com> > > Add the capability to add and remove CPUs on the fly. > The Cortex-A9 offers the possibility to take single cores out of the > MP Core. We add this capabilty taking care that caches are kept > coherent. For the actual shutdown via a WFI instruction, a code snippet > from the omap2 code tree is copied. Thanks for that! For verifying the > shutdown we rely on the internal SH73A0 Power Status Register > PSTR. > > Signed-off-by: Bastian Hecht <hechtb+renesas@gmail.com> > --- > arch/arm/mach-shmobile/headsmp-sh73a0.S | 46 ++++++++++++++++++++++++++ > arch/arm/mach-shmobile/include/mach/common.h | 1 + > arch/arm/mach-shmobile/smp-sh73a0.c | 41 +++++++++++++++++++---- > 3 files changed, 82 insertions(+), 6 deletions(-) > > diff --git a/arch/arm/mach-shmobile/headsmp-sh73a0.S b/arch/arm/mach-shmobile/headsmp-sh73a0.S > index bec4c0d..be463a3 100644 > --- a/arch/arm/mach-shmobile/headsmp-sh73a0.S > +++ b/arch/arm/mach-shmobile/headsmp-sh73a0.S > @@ -23,6 +23,52 @@ > #include <linux/init.h> > #include <asm/memory.h> > > +/* Taken from arch/arm/mach-omap2/sleep44xx.S. Thanks! */ > +ENTRY(sh73a0_do_wfi) > + stmfd sp!, {lr} Why does the lr need to be pushed to the stack? > + > + /* > + * Execute an ISB instruction to ensure that all of the > + * CP15 register changes have been committed. > + */ > + isb Generally writes to cp15 registers that need an isb already do so. > + > + /* > + * Execute a barrier instruction to ensure that all cache, > + * TLB and branch predictor maintenance operations issued > + * by any CPU in the cluster have completed. > + */ > + dsb > + dmb A dsb is a superset of a dmb, so you should not need both. > + > + /* > + * Execute a WFI instruction and wait until the > + * STANDBYWFI output is asserted to indicate that the > + * CPU is in idle and low power state. CPU can specualatively > + * prefetch the instructions so add NOPs after WFI. Sixteen > + * NOPs as per Cortex-A9 pipeline. Why do you care what is prefetched? You're never coming back here, right? Rob > + */ > + wfi @ Wait For Interrupt > + nop > + nop > + nop > + nop > + nop > + nop > + nop > + nop > + nop > + nop > + nop > + nop > + nop > + nop > + nop > + nop > + > + ldmfd sp!, {pc} > +ENDPROC(sh73a0_do_wfi) > + > __CPUINIT > /* > * Reset vector for secondary CPUs. > diff --git a/arch/arm/mach-shmobile/include/mach/common.h b/arch/arm/mach-shmobile/include/mach/common.h > index f2e2c29..40f767e 100644 > --- a/arch/arm/mach-shmobile/include/mach/common.h > +++ b/arch/arm/mach-shmobile/include/mach/common.h > @@ -55,6 +55,7 @@ extern void sh73a0_add_standard_devices(void); > extern void sh73a0_clock_init(void); > extern void sh73a0_pinmux_init(void); > extern void sh73a0_secondary_vector(void); > +extern void sh73a0_do_wfi(void); > extern struct clk sh73a0_extal1_clk; > extern struct clk sh73a0_extal2_clk; > extern struct clk sh73a0_extcki_clk; > diff --git a/arch/arm/mach-shmobile/smp-sh73a0.c b/arch/arm/mach-shmobile/smp-sh73a0.c > index 5e36f5d..9237e13 100644 > --- a/arch/arm/mach-shmobile/smp-sh73a0.c > +++ b/arch/arm/mach-shmobile/smp-sh73a0.c > @@ -24,6 +24,7 @@ > #include <linux/io.h> > #include <linux/delay.h> > #include <mach/common.h> > +#include <asm/cacheflush.h> > #include <asm/smp_plat.h> > #include <mach/sh73a0.h> > #include <asm/smp_scu.h> > @@ -36,6 +37,8 @@ > #define SBAR IOMEM(0xe6180020) > #define APARMBAREA IOMEM(0xe6f10020) > > +#define PSTR_SHUTDOWN_MODE 3 > + > static void __iomem *scu_base_addr(void) > { > return (void __iomem *)0xf0000000; > @@ -92,16 +95,20 @@ static void __init sh73a0_smp_init_cpus(void) > shmobile_smp_init_cpus(ncores); > } > > -static int __maybe_unused sh73a0_cpu_kill(unsigned int cpu) > +#ifdef CONFIG_HOTPLUG_CPU > +static int sh73a0_cpu_kill(unsigned int cpu) > { > + > int k; > + u32 pstr; > > - /* this function is running on another CPU than the offline target, > - * here we need wait for shutdown code in platform_cpu_die() to > - * finish before asking SoC-specific code to power off the CPU core. > + /* > + * wait until the power status register confirms the shutdown of the > + * offline target > */ > for (k = 0; k < 1000; k++) { > - if (shmobile_cpu_is_dead(cpu)) > + pstr = (__raw_readl(PSTR) >> (4 * cpu)) & 3; > + if (pstr == PSTR_SHUTDOWN_MODE) > return 1; > > mdelay(1); > @@ -110,6 +117,28 @@ static int __maybe_unused sh73a0_cpu_kill(unsigned int cpu) > return 0; > } > > +static void sh73a0_cpu_die(unsigned int cpu) > +{ > + /* > + * The ARM MPcore does not issue a cache coherency request for the L1 > + * cache when powering off single CPUs. We must take care of this and > + * further caches. > + */ > + dsb(); > + flush_cache_all(); > + > + /* Set power off mode. This takes the CPU out of the MP cluster */ > + scu_power_mode(scu_base_addr(), SCU_PM_POWEROFF); > + > + /* Enter shutdown mode */ > + sh73a0_do_wfi(); > + > + /* We assume success always. We never reach this */ > + pr_err("Shutting down CPU failed. This should never happen!\n"); > + for (;;) > + ; > +} > +#endif /* CONFIG_HOTPLUG_CPU */ > > struct smp_operations sh73a0_smp_ops __initdata = { > .smp_init_cpus = sh73a0_smp_init_cpus, > @@ -118,7 +147,7 @@ struct smp_operations sh73a0_smp_ops __initdata = { > .smp_boot_secondary = sh73a0_boot_secondary, > #ifdef CONFIG_HOTPLUG_CPU > .cpu_kill = sh73a0_cpu_kill, > - .cpu_die = shmobile_cpu_die, > + .cpu_die = sh73a0_cpu_die, > .cpu_disable = shmobile_cpu_disable, > #endif > }; > -- To unsubscribe from this list: send the line "unsubscribe linux-sh" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
Hi, 2012/12/14 Rob Herring <robherring2@gmail.com>: > On 12/06/2012 06:08 AM, Bastian Hecht wrote: >> From: Bastian Hecht <hechtb@gmail.com> >> >> Add the capability to add and remove CPUs on the fly. >> The Cortex-A9 offers the possibility to take single cores out of the >> MP Core. We add this capabilty taking care that caches are kept >> coherent. For the actual shutdown via a WFI instruction, a code snippet >> from the omap2 code tree is copied. Thanks for that! For verifying the >> shutdown we rely on the internal SH73A0 Power Status Register >> PSTR. >> >> Signed-off-by: Bastian Hecht <hechtb+renesas@gmail.com> >> --- >> arch/arm/mach-shmobile/headsmp-sh73a0.S | 46 ++++++++++++++++++++++++++ >> arch/arm/mach-shmobile/include/mach/common.h | 1 + >> arch/arm/mach-shmobile/smp-sh73a0.c | 41 +++++++++++++++++++---- >> 3 files changed, 82 insertions(+), 6 deletions(-) >> >> diff --git a/arch/arm/mach-shmobile/headsmp-sh73a0.S b/arch/arm/mach-shmobile/headsmp-sh73a0.S >> index bec4c0d..be463a3 100644 >> --- a/arch/arm/mach-shmobile/headsmp-sh73a0.S >> +++ b/arch/arm/mach-shmobile/headsmp-sh73a0.S >> @@ -23,6 +23,52 @@ >> #include <linux/init.h> >> #include <asm/memory.h> >> >> +/* Taken from arch/arm/mach-omap2/sleep44xx.S. Thanks! */ >> +ENTRY(sh73a0_do_wfi) >> + stmfd sp!, {lr} > > Why does the lr need to be pushed to the stack? Yes I must admit this is paradox - we never return but prepare to do so... In the OMAP code they've got a lead out code in case the WFI doesn't succeed. I see no reason how this could ever happen here but to take a safe route I've decided to keep the mechanism to be able to return and spit out an error message back in the C code. >> + >> + /* >> + * Execute an ISB instruction to ensure that all of the >> + * CP15 register changes have been committed. >> + */ >> + isb > > Generally writes to cp15 registers that need an isb already do so. Ok nice, I'll check that and throw it out. >> + >> + /* >> + * Execute a barrier instruction to ensure that all cache, >> + * TLB and branch predictor maintenance operations issued >> + * by any CPU in the cluster have completed. >> + */ >> + dsb >> + dmb > > A dsb is a superset of a dmb, so you should not need both. Same here. >> + >> + /* >> + * Execute a WFI instruction and wait until the >> + * STANDBYWFI output is asserted to indicate that the >> + * CPU is in idle and low power state. CPU can specualatively >> + * prefetch the instructions so add NOPs after WFI. Sixteen >> + * NOPs as per Cortex-A9 pipeline. > > Why do you care what is prefetched? You're never coming back here, right? We can jump back to the paradox top. The idea seems to be to have a clean pipeline in case the WFI doesn't succeed. The thing about this whole code snippet is: I saw no reason to reinvent the wheel and tinker on my own solution when there is code that does the job in a clean way. I thought this could maybe be moved to a general ARM code base when more people rely on it. cheers, Bastian > Rob > >> + */ >> + wfi @ Wait For Interrupt >> + nop >> + nop >> + nop >> + nop >> + nop >> + nop >> + nop >> + nop >> + nop >> + nop >> + nop >> + nop >> + nop >> + nop >> + nop >> + nop >> + >> + ldmfd sp!, {pc} >> +ENDPROC(sh73a0_do_wfi) >> + >> __CPUINIT >> /* >> * Reset vector for secondary CPUs. >> diff --git a/arch/arm/mach-shmobile/include/mach/common.h b/arch/arm/mach-shmobile/include/mach/common.h >> index f2e2c29..40f767e 100644 >> --- a/arch/arm/mach-shmobile/include/mach/common.h >> +++ b/arch/arm/mach-shmobile/include/mach/common.h >> @@ -55,6 +55,7 @@ extern void sh73a0_add_standard_devices(void); >> extern void sh73a0_clock_init(void); >> extern void sh73a0_pinmux_init(void); >> extern void sh73a0_secondary_vector(void); >> +extern void sh73a0_do_wfi(void); >> extern struct clk sh73a0_extal1_clk; >> extern struct clk sh73a0_extal2_clk; >> extern struct clk sh73a0_extcki_clk; >> diff --git a/arch/arm/mach-shmobile/smp-sh73a0.c b/arch/arm/mach-shmobile/smp-sh73a0.c >> index 5e36f5d..9237e13 100644 >> --- a/arch/arm/mach-shmobile/smp-sh73a0.c >> +++ b/arch/arm/mach-shmobile/smp-sh73a0.c >> @@ -24,6 +24,7 @@ >> #include <linux/io.h> >> #include <linux/delay.h> >> #include <mach/common.h> >> +#include <asm/cacheflush.h> >> #include <asm/smp_plat.h> >> #include <mach/sh73a0.h> >> #include <asm/smp_scu.h> >> @@ -36,6 +37,8 @@ >> #define SBAR IOMEM(0xe6180020) >> #define APARMBAREA IOMEM(0xe6f10020) >> >> +#define PSTR_SHUTDOWN_MODE 3 >> + >> static void __iomem *scu_base_addr(void) >> { >> return (void __iomem *)0xf0000000; >> @@ -92,16 +95,20 @@ static void __init sh73a0_smp_init_cpus(void) >> shmobile_smp_init_cpus(ncores); >> } >> >> -static int __maybe_unused sh73a0_cpu_kill(unsigned int cpu) >> +#ifdef CONFIG_HOTPLUG_CPU >> +static int sh73a0_cpu_kill(unsigned int cpu) >> { >> + >> int k; >> + u32 pstr; >> >> - /* this function is running on another CPU than the offline target, >> - * here we need wait for shutdown code in platform_cpu_die() to >> - * finish before asking SoC-specific code to power off the CPU core. >> + /* >> + * wait until the power status register confirms the shutdown of the >> + * offline target >> */ >> for (k = 0; k < 1000; k++) { >> - if (shmobile_cpu_is_dead(cpu)) >> + pstr = (__raw_readl(PSTR) >> (4 * cpu)) & 3; >> + if (pstr == PSTR_SHUTDOWN_MODE) >> return 1; >> >> mdelay(1); >> @@ -110,6 +117,28 @@ static int __maybe_unused sh73a0_cpu_kill(unsigned int cpu) >> return 0; >> } >> >> +static void sh73a0_cpu_die(unsigned int cpu) >> +{ >> + /* >> + * The ARM MPcore does not issue a cache coherency request for the L1 >> + * cache when powering off single CPUs. We must take care of this and >> + * further caches. >> + */ >> + dsb(); >> + flush_cache_all(); >> + >> + /* Set power off mode. This takes the CPU out of the MP cluster */ >> + scu_power_mode(scu_base_addr(), SCU_PM_POWEROFF); >> + >> + /* Enter shutdown mode */ >> + sh73a0_do_wfi(); >> + >> + /* We assume success always. We never reach this */ >> + pr_err("Shutting down CPU failed. This should never happen!\n"); >> + for (;;) >> + ; >> +} >> +#endif /* CONFIG_HOTPLUG_CPU */ >> >> struct smp_operations sh73a0_smp_ops __initdata = { >> .smp_init_cpus = sh73a0_smp_init_cpus, >> @@ -118,7 +147,7 @@ struct smp_operations sh73a0_smp_ops __initdata = { >> .smp_boot_secondary = sh73a0_boot_secondary, >> #ifdef CONFIG_HOTPLUG_CPU >> .cpu_kill = sh73a0_cpu_kill, >> - .cpu_die = shmobile_cpu_die, >> + .cpu_die = sh73a0_cpu_die, >> .cpu_disable = shmobile_cpu_disable, >> #endif >> }; >> > -- To unsubscribe from this list: send the line "unsubscribe linux-sh" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
On 12/14/2012 09:33 AM, Bastian Hecht wrote: > Hi, > > 2012/12/14 Rob Herring <robherring2@gmail.com>: >> On 12/06/2012 06:08 AM, Bastian Hecht wrote: >>> From: Bastian Hecht <hechtb@gmail.com> >>> >>> Add the capability to add and remove CPUs on the fly. >>> The Cortex-A9 offers the possibility to take single cores out of the >>> MP Core. We add this capabilty taking care that caches are kept >>> coherent. For the actual shutdown via a WFI instruction, a code snippet >>> from the omap2 code tree is copied. Thanks for that! For verifying the >>> shutdown we rely on the internal SH73A0 Power Status Register >>> PSTR. >>> >>> Signed-off-by: Bastian Hecht <hechtb+renesas@gmail.com> >>> --- >>> arch/arm/mach-shmobile/headsmp-sh73a0.S | 46 ++++++++++++++++++++++++++ >>> arch/arm/mach-shmobile/include/mach/common.h | 1 + >>> arch/arm/mach-shmobile/smp-sh73a0.c | 41 +++++++++++++++++++---- >>> 3 files changed, 82 insertions(+), 6 deletions(-) >>> >>> diff --git a/arch/arm/mach-shmobile/headsmp-sh73a0.S b/arch/arm/mach-shmobile/headsmp-sh73a0.S >>> index bec4c0d..be463a3 100644 >>> --- a/arch/arm/mach-shmobile/headsmp-sh73a0.S >>> +++ b/arch/arm/mach-shmobile/headsmp-sh73a0.S >>> @@ -23,6 +23,52 @@ >>> #include <linux/init.h> >>> #include <asm/memory.h> >>> >>> +/* Taken from arch/arm/mach-omap2/sleep44xx.S. Thanks! */ >>> +ENTRY(sh73a0_do_wfi) >>> + stmfd sp!, {lr} >> >> Why does the lr need to be pushed to the stack? > > Yes I must admit this is paradox - we never return but prepare to do > so... In the OMAP code they've got a lead out code in case the WFI > doesn't succeed. I see no reason how this could ever happen here but > to take a safe route I've decided to keep the mechanism to be able to > return and spit out an error message back in the C code. It's not clear to me that OMAP needed this either. The lr value would have to get lost during wfi. >>> + >>> + /* >>> + * Execute an ISB instruction to ensure that all of the >>> + * CP15 register changes have been committed. >>> + */ >>> + isb >> >> Generally writes to cp15 registers that need an isb already do so. > > Ok nice, I'll check that and throw it out. > >>> + >>> + /* >>> + * Execute a barrier instruction to ensure that all cache, >>> + * TLB and branch predictor maintenance operations issued >>> + * by any CPU in the cluster have completed. >>> + */ >>> + dsb >>> + dmb >> >> A dsb is a superset of a dmb, so you should not need both. > > Same here. > >>> + >>> + /* >>> + * Execute a WFI instruction and wait until the >>> + * STANDBYWFI output is asserted to indicate that the >>> + * CPU is in idle and low power state. CPU can specualatively >>> + * prefetch the instructions so add NOPs after WFI. Sixteen >>> + * NOPs as per Cortex-A9 pipeline. >> >> Why do you care what is prefetched? You're never coming back here, right? > > We can jump back to the paradox top. The idea seems to be to have a > clean pipeline in case the WFI doesn't succeed. > The thing about this whole code snippet is: I saw no reason to > reinvent the wheel and tinker on my own solution when there is code > that does the job in a clean way. I thought this could maybe be moved > to a general ARM code base when more people rely on it. > Blindly copying code is reinventing the wheel. You are making it appear that this is needed, but don't seem to have any reason why other than OMAP did it. If it is in fact needed, then it should be common. Use cpu_do_idle or figure out and explain why you can't. It's important to know that if we do go and consolidate this code later. Rob -- To unsubscribe from this list: send the line "unsubscribe linux-sh" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
Hi Rob, 2012/12/14 Rob Herring <robherring2@gmail.com>: > On 12/14/2012 09:33 AM, Bastian Hecht wrote: >> Hi, >> >> 2012/12/14 Rob Herring <robherring2@gmail.com>: >>> On 12/06/2012 06:08 AM, Bastian Hecht wrote: >>>> From: Bastian Hecht <hechtb@gmail.com> >>>> >>>> Add the capability to add and remove CPUs on the fly. >>>> The Cortex-A9 offers the possibility to take single cores out of the >>>> MP Core. We add this capabilty taking care that caches are kept >>>> coherent. For the actual shutdown via a WFI instruction, a code snippet >>>> from the omap2 code tree is copied. Thanks for that! For verifying the >>>> shutdown we rely on the internal SH73A0 Power Status Register >>>> PSTR. >>>> >>>> Signed-off-by: Bastian Hecht <hechtb+renesas@gmail.com> >>>> --- >>>> arch/arm/mach-shmobile/headsmp-sh73a0.S | 46 ++++++++++++++++++++++++++ >>>> arch/arm/mach-shmobile/include/mach/common.h | 1 + >>>> arch/arm/mach-shmobile/smp-sh73a0.c | 41 +++++++++++++++++++---- >>>> 3 files changed, 82 insertions(+), 6 deletions(-) >>>> >>>> diff --git a/arch/arm/mach-shmobile/headsmp-sh73a0.S b/arch/arm/mach-shmobile/headsmp-sh73a0.S >>>> index bec4c0d..be463a3 100644 >>>> --- a/arch/arm/mach-shmobile/headsmp-sh73a0.S >>>> +++ b/arch/arm/mach-shmobile/headsmp-sh73a0.S >>>> @@ -23,6 +23,52 @@ >>>> #include <linux/init.h> >>>> #include <asm/memory.h> >>>> >>>> +/* Taken from arch/arm/mach-omap2/sleep44xx.S. Thanks! */ >>>> +ENTRY(sh73a0_do_wfi) >>>> + stmfd sp!, {lr} >>> >>> Why does the lr need to be pushed to the stack? >> >> Yes I must admit this is paradox - we never return but prepare to do >> so... In the OMAP code they've got a lead out code in case the WFI >> doesn't succeed. I see no reason how this could ever happen here but >> to take a safe route I've decided to keep the mechanism to be able to >> return and spit out an error message back in the C code. > > It's not clear to me that OMAP needed this either. The lr value would > have to get lost during wfi. > >>>> + >>>> + /* >>>> + * Execute an ISB instruction to ensure that all of the >>>> + * CP15 register changes have been committed. >>>> + */ >>>> + isb >>> >>> Generally writes to cp15 registers that need an isb already do so. >> >> Ok nice, I'll check that and throw it out. >> >>>> + >>>> + /* >>>> + * Execute a barrier instruction to ensure that all cache, >>>> + * TLB and branch predictor maintenance operations issued >>>> + * by any CPU in the cluster have completed. >>>> + */ >>>> + dsb >>>> + dmb >>> >>> A dsb is a superset of a dmb, so you should not need both. >> >> Same here. >> >>>> + >>>> + /* >>>> + * Execute a WFI instruction and wait until the >>>> + * STANDBYWFI output is asserted to indicate that the >>>> + * CPU is in idle and low power state. CPU can specualatively >>>> + * prefetch the instructions so add NOPs after WFI. Sixteen >>>> + * NOPs as per Cortex-A9 pipeline. >>> >>> Why do you care what is prefetched? You're never coming back here, right? >> >> We can jump back to the paradox top. The idea seems to be to have a >> clean pipeline in case the WFI doesn't succeed. >> The thing about this whole code snippet is: I saw no reason to >> reinvent the wheel and tinker on my own solution when there is code >> that does the job in a clean way. I thought this could maybe be moved >> to a general ARM code base when more people rely on it. >> > > Blindly copying code is reinventing the wheel. You are making it appear > that this is needed, but don't seem to have any reason why other than > OMAP did it. If it is in fact needed, then it should be common. > > Use cpu_do_idle or figure out and explain why you can't. It's important > to know that if we do go and consolidate this code later. Yes after thinking about it a bit, I must completely agree to you. Copying OMAP's code was done because of hesitation and uncertainty that I could miss something and brings the drawbacks that you mentioned. It's much straighter to go with cpu_do_idle. Thanks! Bastian > Rob > -- To unsubscribe from this list: send the line "unsubscribe linux-sh" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
diff --git a/arch/arm/mach-shmobile/headsmp-sh73a0.S b/arch/arm/mach-shmobile/headsmp-sh73a0.S index bec4c0d..be463a3 100644 --- a/arch/arm/mach-shmobile/headsmp-sh73a0.S +++ b/arch/arm/mach-shmobile/headsmp-sh73a0.S @@ -23,6 +23,52 @@ #include <linux/init.h> #include <asm/memory.h> +/* Taken from arch/arm/mach-omap2/sleep44xx.S. Thanks! */ +ENTRY(sh73a0_do_wfi) + stmfd sp!, {lr} + + /* + * Execute an ISB instruction to ensure that all of the + * CP15 register changes have been committed. + */ + isb + + /* + * Execute a barrier instruction to ensure that all cache, + * TLB and branch predictor maintenance operations issued + * by any CPU in the cluster have completed. + */ + dsb + dmb + + /* + * Execute a WFI instruction and wait until the + * STANDBYWFI output is asserted to indicate that the + * CPU is in idle and low power state. CPU can specualatively + * prefetch the instructions so add NOPs after WFI. Sixteen + * NOPs as per Cortex-A9 pipeline. + */ + wfi @ Wait For Interrupt + nop + nop + nop + nop + nop + nop + nop + nop + nop + nop + nop + nop + nop + nop + nop + nop + + ldmfd sp!, {pc} +ENDPROC(sh73a0_do_wfi) + __CPUINIT /* * Reset vector for secondary CPUs. diff --git a/arch/arm/mach-shmobile/include/mach/common.h b/arch/arm/mach-shmobile/include/mach/common.h index f2e2c29..40f767e 100644 --- a/arch/arm/mach-shmobile/include/mach/common.h +++ b/arch/arm/mach-shmobile/include/mach/common.h @@ -55,6 +55,7 @@ extern void sh73a0_add_standard_devices(void); extern void sh73a0_clock_init(void); extern void sh73a0_pinmux_init(void); extern void sh73a0_secondary_vector(void); +extern void sh73a0_do_wfi(void); extern struct clk sh73a0_extal1_clk; extern struct clk sh73a0_extal2_clk; extern struct clk sh73a0_extcki_clk; diff --git a/arch/arm/mach-shmobile/smp-sh73a0.c b/arch/arm/mach-shmobile/smp-sh73a0.c index 5e36f5d..9237e13 100644 --- a/arch/arm/mach-shmobile/smp-sh73a0.c +++ b/arch/arm/mach-shmobile/smp-sh73a0.c @@ -24,6 +24,7 @@ #include <linux/io.h> #include <linux/delay.h> #include <mach/common.h> +#include <asm/cacheflush.h> #include <asm/smp_plat.h> #include <mach/sh73a0.h> #include <asm/smp_scu.h> @@ -36,6 +37,8 @@ #define SBAR IOMEM(0xe6180020) #define APARMBAREA IOMEM(0xe6f10020) +#define PSTR_SHUTDOWN_MODE 3 + static void __iomem *scu_base_addr(void) { return (void __iomem *)0xf0000000; @@ -92,16 +95,20 @@ static void __init sh73a0_smp_init_cpus(void) shmobile_smp_init_cpus(ncores); } -static int __maybe_unused sh73a0_cpu_kill(unsigned int cpu) +#ifdef CONFIG_HOTPLUG_CPU +static int sh73a0_cpu_kill(unsigned int cpu) { + int k; + u32 pstr; - /* this function is running on another CPU than the offline target, - * here we need wait for shutdown code in platform_cpu_die() to - * finish before asking SoC-specific code to power off the CPU core. + /* + * wait until the power status register confirms the shutdown of the + * offline target */ for (k = 0; k < 1000; k++) { - if (shmobile_cpu_is_dead(cpu)) + pstr = (__raw_readl(PSTR) >> (4 * cpu)) & 3; + if (pstr == PSTR_SHUTDOWN_MODE) return 1; mdelay(1); @@ -110,6 +117,28 @@ static int __maybe_unused sh73a0_cpu_kill(unsigned int cpu) return 0; } +static void sh73a0_cpu_die(unsigned int cpu) +{ + /* + * The ARM MPcore does not issue a cache coherency request for the L1 + * cache when powering off single CPUs. We must take care of this and + * further caches. + */ + dsb(); + flush_cache_all(); + + /* Set power off mode. This takes the CPU out of the MP cluster */ + scu_power_mode(scu_base_addr(), SCU_PM_POWEROFF); + + /* Enter shutdown mode */ + sh73a0_do_wfi(); + + /* We assume success always. We never reach this */ + pr_err("Shutting down CPU failed. This should never happen!\n"); + for (;;) + ; +} +#endif /* CONFIG_HOTPLUG_CPU */ struct smp_operations sh73a0_smp_ops __initdata = { .smp_init_cpus = sh73a0_smp_init_cpus, @@ -118,7 +147,7 @@ struct smp_operations sh73a0_smp_ops __initdata = { .smp_boot_secondary = sh73a0_boot_secondary, #ifdef CONFIG_HOTPLUG_CPU .cpu_kill = sh73a0_cpu_kill, - .cpu_die = shmobile_cpu_die, + .cpu_die = sh73a0_cpu_die, .cpu_disable = shmobile_cpu_disable, #endif };