From mboxrd@z Thu Jan 1 00:00:00 1970 From: u.kleine-koenig@pengutronix.de (Uwe =?iso-8859-1?Q?Kleine-K=F6nig?=) Date: Mon, 6 May 2013 11:30:59 +0200 Subject: [RFC PATCH] implement read_cpuid_ext for v7-M (Was: Re: [PATCHv2 2/3] ARM: Detect support for SDIV/UDIV from ISAR0) register In-Reply-To: <20130418091019.GA21099@pengutronix.de> References: <1363631337-13816-1-git-send-email-sboyd@codeaurora.org> <1363631337-13816-3-git-send-email-sboyd@codeaurora.org> <20130418091019.GA21099@pengutronix.de> Message-ID: <20130506093059.GH23285@pengutronix.de> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org Hello, On Thu, Apr 18, 2013 at 11:10:19AM +0200, Uwe Kleine-K?nig wrote: > On Mon, Mar 18, 2013 at 11:28:56AM -0700, Stephen Boyd wrote: > > The ISAR0 register indicates support for the SDIV and UDIV > > instructions in both the Thumb and ARM instruction set. Read the > > register to detect the supported instructions and update the > > elf_hwcap mask as appropriate. This is better than adding more > > and more cpuid checks in proc-v7.S for each new cpu variant that > > supports these instructions. > you pointed out yesterday that this could work on v7-m, too. As I based > my patches on 3.9-rc1 this patch (8164f7af88) wasn't included. When > updating this results in a warning, because I have > > 6ebd4d0 (ARM: stub out read_cpuid and read_cpuid_ext for CPU_CP15=n) > > from rmk's devel-stable branch. > > > Acked-by: Will Deacon > > Cc: Stepan Moskovchenko > > Signed-off-by: Stephen Boyd > > --- > > arch/arm/kernel/setup.c | 20 ++++++++++++++++++++ > > arch/arm/mm/proc-v7.S | 4 ++-- > > 2 files changed, 22 insertions(+), 2 deletions(-) > > > > diff --git a/arch/arm/kernel/setup.c b/arch/arm/kernel/setup.c > > index e2c8bbf..f3ac13f 100644 > > --- a/arch/arm/kernel/setup.c > > +++ b/arch/arm/kernel/setup.c > > @@ -353,6 +353,23 @@ void __init early_print(const char *str, ...) > > printk("%s", buf); > > } > > > > +static void __init cpuid_init_hwcaps(void) > > +{ > > + unsigned int divide_instrs; > > + > > + if (cpu_architecture() < CPU_ARCH_ARMv7) > > + return; > > + > > + divide_instrs = (read_cpuid_ext(CPUID_EXT_ISAR0) & 0x0f000000) >> 24; > The problem is that read_cpuid_ext is called which doesn't map to > something useful for v7-m. So maybe add a check: > > if (!IS_ENABLED(CONFIG_CPU_CP15)) > return; > > ? The patch below fixes the issue for me on V7-M. The only drawback is that the list of registers isn't shared. Maybe someone has a nice idea? BTW, there doesn't seem to be an equivalent register set for CPUID_{CACHETYPE,TCM,TLBTYPE,MPIDR} on v7-M. Best regards Uwe diff --git a/arch/arm/include/asm/cputype.h b/arch/arm/include/asm/cputype.h index 4eb94a3..ec635ff 100644 --- a/arch/arm/include/asm/cputype.h +++ b/arch/arm/include/asm/cputype.h @@ -10,6 +10,22 @@ #define CPUID_TLBTYPE 3 #define CPUID_MPIDR 5 +#ifdef CONFIG_CPU_V7M +#define CPUID_EXT_PFR0 0x40 +#define CPUID_EXT_PFR1 0x44 +#define CPUID_EXT_DFR0 0x48 +#define CPUID_EXT_AFR0 0x4c +#define CPUID_EXT_MMFR0 0x50 +#define CPUID_EXT_MMFR1 0x54 +#define CPUID_EXT_MMFR2 0x58 +#define CPUID_EXT_MMFR3 0x5c +#define CPUID_EXT_ISAR0 0x60 +#define CPUID_EXT_ISAR1 0x64 +#define CPUID_EXT_ISAR2 0x68 +#define CPUID_EXT_ISAR3 0x6c +#define CPUID_EXT_ISAR4 0x70 +#define CPUID_EXT_ISAR5 0x74 +#else #define CPUID_EXT_PFR0 "c1, 0" #define CPUID_EXT_PFR1 "c1, 1" #define CPUID_EXT_DFR0 "c1, 2" @@ -24,6 +40,7 @@ #define CPUID_EXT_ISAR3 "c2, 3" #define CPUID_EXT_ISAR4 "c2, 4" #define CPUID_EXT_ISAR5 "c2, 5" +#endif #define MPIDR_SMP_BITMASK (0x3 << 30) #define MPIDR_SMP_VALUE (0x2 << 30) @@ -79,7 +96,23 @@ extern unsigned int processor_id; __val; \ }) -#else /* ifdef CONFIG_CPU_CP15 */ +#elif defined(CONFIG_CPU_V7M) + +#include +#include + +#define read_cpuid(reg) \ + ({ \ + WARN_ON_ONCE(1); \ + 0; \ + }) + +static inline unsigned int __attribute_const__ read_cpuid_ext(unsigned offset) +{ + return readl(BASEADDR_V7M_SCB + offset); +} + +#else /* ifdef CONFIG_CPU_CP15 / elif defined (CONFIG_CPU_V7M) */ /* * read_cpuid and read_cpuid_ext should only ever be called on machines that @@ -108,9 +141,6 @@ static inline unsigned int __attribute_const__ read_cpuid_id(void) #elif defined(CONFIG_CPU_V7M) -#include -#include - static inline unsigned int __attribute_const__ read_cpuid_id(void) { return readl(BASEADDR_V7M_SCB + V7M_SCB_CPUID); diff --git a/arch/arm/mm/proc-v7m.S b/arch/arm/mm/proc-v7m.S index 000499c..0c93588 100644 --- a/arch/arm/mm/proc-v7m.S +++ b/arch/arm/mm/proc-v7m.S @@ -144,7 +144,7 @@ __v7m_proc_info: b __v7m_setup @ proc_info_list.__cpu_flush .long cpu_arch_name .long cpu_elf_name - .long HWCAP_HALF|HWCAP_THUMB|HWCAP_FAST_MULT|HWCAP_IDIVT + .long HWCAP_HALF|HWCAP_THUMB|HWCAP_FAST_MULT .long cpu_v7m_name .long v7m_processor_functions @ proc_info_list.proc .long 0 @ proc_info_list.tlb -- Pengutronix e.K. | Uwe Kleine-K?nig | Industrial Linux Solutions | http://www.pengutronix.de/ |