| Message ID | 1426197361-19290-5-git-send-email-maxime.coquelin@st.com |
|---|---|
| State | New |
| Headers | show |
On 03/12/2015 10:55 PM, Maxime Coquelin wrote: > From: Maxime Coquelin <mcoquelin.stm32@gmail.com> > > This patch adds clocksource support for ARMv7-M's System timer, > also known as SysTick. > > Signed-off-by: Maxime Coquelin <mcoquelin.stm32@gmail.com> Hi Maxime, the driver looks good. Three comments below. -- Daniel > --- > drivers/clocksource/Kconfig | 7 ++++ > drivers/clocksource/Makefile | 1 + > drivers/clocksource/armv7m_systick.c | 78 ++++++++++++++++++++++++++++++++++++ > 3 files changed, 86 insertions(+) > create mode 100644 drivers/clocksource/armv7m_systick.c > > diff --git a/drivers/clocksource/Kconfig b/drivers/clocksource/Kconfig > index 1c2506f..b82e58b 100644 > --- a/drivers/clocksource/Kconfig > +++ b/drivers/clocksource/Kconfig > @@ -134,6 +134,13 @@ config CLKSRC_ARM_GLOBAL_TIMER_SCHED_CLOCK > help > Use ARM global timer clock source as sched_clock > > +config ARMV7M_SYSTICK > + bool > + select CLKSRC_OF if OF > + select CLKSRC_MMIO > + help > + This options enables support for the ARMv7M system timer unit > + > config ATMEL_PIT > select CLKSRC_OF if OF > def_bool SOC_AT91SAM9 || SOC_SAMA5 > diff --git a/drivers/clocksource/Makefile b/drivers/clocksource/Makefile > index 752d5c7..1c9a643 100644 > --- a/drivers/clocksource/Makefile > +++ b/drivers/clocksource/Makefile > @@ -44,6 +44,7 @@ obj-$(CONFIG_MTK_TIMER) += mtk_timer.o > > obj-$(CONFIG_ARM_ARCH_TIMER) += arm_arch_timer.o > obj-$(CONFIG_ARM_GLOBAL_TIMER) += arm_global_timer.o > +obj-$(CONFIG_ARMV7M_SYSTICK) += armv7m_systick.o > obj-$(CONFIG_CLKSRC_METAG_GENERIC) += metag_generic.o > obj-$(CONFIG_ARCH_HAS_TICK_BROADCAST) += dummy_timer.o > obj-$(CONFIG_ARCH_KEYSTONE) += timer-keystone.o > diff --git a/drivers/clocksource/armv7m_systick.c b/drivers/clocksource/armv7m_systick.c > new file mode 100644 > index 0000000..23d8249 > --- /dev/null > +++ b/drivers/clocksource/armv7m_systick.c > @@ -0,0 +1,78 @@ > +/* > + * Copyright (C) Maxime Coquelin 2015 > + * Author: Maxime Coquelin <mcoquelin.stm32@gmail.com> > + * License terms: GNU General Public License (GPL), version 2 > + */ > + > +#include <linux/kernel.h> > +#include <linux/clocksource.h> > +#include <linux/clockchips.h> > +#include <linux/of.h> > +#include <linux/of_address.h> > +#include <linux/clk.h> > +#include <linux/bitops.h> > + > +#define SYST_CSR 0x00 > +#define SYST_RVR 0x04 > +#define SYST_CVR 0x08 > +#define SYST_CALIB 0x0c > + > +#define SYST_CSR_ENABLE BIT(0) > + > +#define SYSTICK_LOAD_RELOAD_MASK 0x00FFFFFF > + > +static void __init system_timer_of_register(struct device_node *np) > +{ > + struct clk *clk; > + void __iomem *base; > + u32 rate = 0; > + int ret; > + > + base = of_iomap(np, 0); > + if (!base) { > + pr_warn("system-timer: invalid base address\n"); > + return; > + } > + > + clk = of_clk_get(np, 0); > + if (!IS_ERR(clk)) { > + ret = clk_prepare_enable(clk); > + if (ret) { > + clk_put(clk); > + goto out_unmap; > + } > + > + rate = clk_get_rate(clk); > + } > + > + /* If no clock found, try to get clock-frequency property */ > + if (!rate) { > + ret = of_property_read_u32(np, "clock-frequency", &rate); > + if (ret) > + goto out_unmap; Shouldn't be 'goto out_clk_disable' ? > + } > + > + writel_relaxed(SYSTICK_LOAD_RELOAD_MASK, base + SYST_RVR); > + writel_relaxed(SYST_CSR_ENABLE, base + SYST_CSR); > + > + ret = clocksource_mmio_init(base + SYST_CVR, "arm_system_timer", rate, > + 200, 24, clocksource_mmio_readl_down); > + if (ret) { > + pr_err("failed to init clocksource (%d)\n", ret); > + goto out_clk_disable; > + } > + > + pr_info("ARM System timer initialized as clocksource\n"); > + > + return; > + > +out_clk_disable: > + if (!IS_ERR(clk)) Why do you need this check ? It isn't missing a clk_put ? > + clk_disable_unprepare(clk); > +out_unmap: > + iounmap(base); > + WARN(ret, "ARM System timer register failed (%d)\n", ret); > +} > + > +CLOCKSOURCE_OF_DECLARE(arm_systick, "arm,armv7m-systick", > + system_timer_of_register); >
Hi Daniel, Thanks for the review. Please find my answers below. 2015-03-26 10:50 GMT+01:00 Daniel Lezcano <daniel.lezcano@linaro.org>: > On 03/12/2015 10:55 PM, Maxime Coquelin wrote: >> >> From: Maxime Coquelin <mcoquelin.stm32@gmail.com> >> >> This patch adds clocksource support for ARMv7-M's System timer, >> also known as SysTick. >> >> Signed-off-by: Maxime Coquelin <mcoquelin.stm32@gmail.com> > > > Hi Maxime, > > the driver looks good. Three comments below. > > -- Daniel > > >> --- >> drivers/clocksource/Kconfig | 7 ++++ >> drivers/clocksource/Makefile | 1 + >> drivers/clocksource/armv7m_systick.c | 78 >> ++++++++++++++++++++++++++++++++++++ >> 3 files changed, 86 insertions(+) >> create mode 100644 drivers/clocksource/armv7m_systick.c >> >> diff --git a/drivers/clocksource/Kconfig b/drivers/clocksource/Kconfig >> index 1c2506f..b82e58b 100644 >> --- a/drivers/clocksource/Kconfig >> +++ b/drivers/clocksource/Kconfig >> @@ -134,6 +134,13 @@ config CLKSRC_ARM_GLOBAL_TIMER_SCHED_CLOCK >> help >> Use ARM global timer clock source as sched_clock >> >> +config ARMV7M_SYSTICK >> + bool >> + select CLKSRC_OF if OF >> + select CLKSRC_MMIO >> + help >> + This options enables support for the ARMv7M system timer unit >> + >> config ATMEL_PIT >> select CLKSRC_OF if OF >> def_bool SOC_AT91SAM9 || SOC_SAMA5 >> diff --git a/drivers/clocksource/Makefile b/drivers/clocksource/Makefile >> index 752d5c7..1c9a643 100644 >> --- a/drivers/clocksource/Makefile >> +++ b/drivers/clocksource/Makefile >> @@ -44,6 +44,7 @@ obj-$(CONFIG_MTK_TIMER) += mtk_timer.o >> >> obj-$(CONFIG_ARM_ARCH_TIMER) += arm_arch_timer.o >> obj-$(CONFIG_ARM_GLOBAL_TIMER) += arm_global_timer.o >> +obj-$(CONFIG_ARMV7M_SYSTICK) += armv7m_systick.o >> obj-$(CONFIG_CLKSRC_METAG_GENERIC) += metag_generic.o >> obj-$(CONFIG_ARCH_HAS_TICK_BROADCAST) += dummy_timer.o >> obj-$(CONFIG_ARCH_KEYSTONE) += timer-keystone.o >> diff --git a/drivers/clocksource/armv7m_systick.c >> b/drivers/clocksource/armv7m_systick.c >> new file mode 100644 >> index 0000000..23d8249 >> --- /dev/null >> +++ b/drivers/clocksource/armv7m_systick.c >> @@ -0,0 +1,78 @@ >> +/* >> + * Copyright (C) Maxime Coquelin 2015 >> + * Author: Maxime Coquelin <mcoquelin.stm32@gmail.com> >> + * License terms: GNU General Public License (GPL), version 2 >> + */ >> + >> +#include <linux/kernel.h> >> +#include <linux/clocksource.h> >> +#include <linux/clockchips.h> >> +#include <linux/of.h> >> +#include <linux/of_address.h> >> +#include <linux/clk.h> >> +#include <linux/bitops.h> >> + >> +#define SYST_CSR 0x00 >> +#define SYST_RVR 0x04 >> +#define SYST_CVR 0x08 >> +#define SYST_CALIB 0x0c >> + >> +#define SYST_CSR_ENABLE BIT(0) >> + >> +#define SYSTICK_LOAD_RELOAD_MASK 0x00FFFFFF >> + >> +static void __init system_timer_of_register(struct device_node *np) >> +{ >> + struct clk *clk; >> + void __iomem *base; >> + u32 rate = 0; >> + int ret; >> + >> + base = of_iomap(np, 0); >> + if (!base) { >> + pr_warn("system-timer: invalid base address\n"); >> + return; >> + } >> + >> + clk = of_clk_get(np, 0); >> + if (!IS_ERR(clk)) { >> + ret = clk_prepare_enable(clk); >> + if (ret) { >> + clk_put(clk); >> + goto out_unmap; >> + } >> + >> + rate = clk_get_rate(clk); >> + } >> + >> + /* If no clock found, try to get clock-frequency property */ >> + if (!rate) { >> + ret = of_property_read_u32(np, "clock-frequency", &rate); >> + if (ret) >> + goto out_unmap; > > > Shouldn't be 'goto out_clk_disable' ? No, because I assumed !rate means we failed to get the clock. Actually, clk_get_rate could return 0, so relying on rate value is not safe. I propose to get clock-frequency property if IS_ERR(clk). Is it fine for you? > >> + } >> + >> + writel_relaxed(SYSTICK_LOAD_RELOAD_MASK, base + SYST_RVR); >> + writel_relaxed(SYST_CSR_ENABLE, base + SYST_CSR); >> + >> + ret = clocksource_mmio_init(base + SYST_CVR, "arm_system_timer", >> rate, >> + 200, 24, clocksource_mmio_readl_down); >> + if (ret) { >> + pr_err("failed to init clocksource (%d)\n", ret); >> + goto out_clk_disable; >> + } >> + >> + pr_info("ARM System timer initialized as clocksource\n"); >> + >> + return; >> + >> +out_clk_disable: >> + if (!IS_ERR(clk)) > > > Why do you need this check ? To handle the case were no clock was found, but a clk-frequency value was provided. > > It isn't missing a clk_put ? Right, thanks for spotting this. I wonder if it makes sense to implement the error path. If we fail to initialize the clocksource, the system will be unusable. Maybe I should just perform a BUG_ON() in the error cases, as most of the other clocksource drivers do. What is your view? Regards, Maxime > >> + clk_disable_unprepare(clk); >> +out_unmap: >> + iounmap(base); >> + WARN(ret, "ARM System timer register failed (%d)\n", ret); >> +} >> + >> +CLOCKSOURCE_OF_DECLARE(arm_systick, "arm,armv7m-systick", >> + system_timer_of_register); >> > > > -- > <http://www.linaro.org/> Linaro.org │ Open source software for ARM SoCs > > Follow Linaro: <http://www.facebook.com/pages/Linaro> Facebook | > <http://twitter.com/#!/linaroorg> Twitter | > <http://www.linaro.org/linaro-blog/> Blog > -- To unsubscribe from this list: send the line "unsubscribe linux-gpio" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
On 03/26/2015 09:19 PM, Maxime Coquelin wrote: > Hi Daniel, > > Thanks for the review. Please find my answers below. > > 2015-03-26 10:50 GMT+01:00 Daniel Lezcano <daniel.lezcano@linaro.org>: >> On 03/12/2015 10:55 PM, Maxime Coquelin wrote: >>> >>> From: Maxime Coquelin <mcoquelin.stm32@gmail.com> >>> >>> This patch adds clocksource support for ARMv7-M's System timer, >>> also known as SysTick. >>> >>> Signed-off-by: Maxime Coquelin <mcoquelin.stm32@gmail.com> >> >> >> Hi Maxime, >> >> the driver looks good. Three comments below. >> >> -- Daniel >> >> [ ... ] >>> +static void __init system_timer_of_register(struct device_node *np) >>> +{ >>> + struct clk *clk; >>> + void __iomem *base; >>> + u32 rate = 0; >>> + int ret; >>> + >>> + base = of_iomap(np, 0); >>> + if (!base) { >>> + pr_warn("system-timer: invalid base address\n"); >>> + return; >>> + } >>> + >>> + clk = of_clk_get(np, 0); >>> + if (!IS_ERR(clk)) { >>> + ret = clk_prepare_enable(clk); >>> + if (ret) { >>> + clk_put(clk); >>> + goto out_unmap; >>> + } >>> + >>> + rate = clk_get_rate(clk); >>> + } >>> + >>> + /* If no clock found, try to get clock-frequency property */ >>> + if (!rate) { >>> + ret = of_property_read_u32(np, "clock-frequency", &rate); >>> + if (ret) >>> + goto out_unmap; >> >> >> Shouldn't be 'goto out_clk_disable' ? > > No, because I assumed !rate means we failed to get the clock. > Actually, clk_get_rate could return 0, so relying on rate value is not safe. > > I propose to get clock-frequency property if IS_ERR(clk). > > Is it fine for you? Why not invert the conditions ? If the 'clock-frequency' is specified in the DT then it overrides the clk_get_rate(). So the resulting code will be: ret = of_property_read_u32(np, "clock-frequency", &rate); if (ret) { clk = of_clk_get(np, 0); if (IS_ERR(clk)) goto out_unmap; ret = clk_prepare_enable(clk); if (ret) goto out_clk_put; rate = clk_get_rate(clk); if (!rate) goto out_clk_unprepare; } >>> + } >>> + >>> + writel_relaxed(SYSTICK_LOAD_RELOAD_MASK, base + SYST_RVR); >>> + writel_relaxed(SYST_CSR_ENABLE, base + SYST_CSR); >>> + >>> + ret = clocksource_mmio_init(base + SYST_CVR, "arm_system_timer", >>> rate, >>> + 200, 24, clocksource_mmio_readl_down); >>> + if (ret) { >>> + pr_err("failed to init clocksource (%d)\n", ret); >>> + goto out_clk_disable; >>> + } >>> + >>> + pr_info("ARM System timer initialized as clocksource\n"); >>> + >>> + return; >>> + >>> +out_clk_disable: >>> + if (!IS_ERR(clk)) >> >> >> Why do you need this check ? > > To handle the case were no clock was found, but a clk-frequency value > was provided. > >> >> It isn't missing a clk_put ? > > Right, thanks for spotting this. > > I wonder if it makes sense to implement the error path. > If we fail to initialize the clocksource, the system will be unusable. > > Maybe I should just perform a BUG_ON() in the error cases, as most of > the other clocksource drivers do. > What is your view? I prefer to not BUG_ON in the init functions because it already happen that drivers were bugging at init time and when a driver was reused on another platform with several timers available, the board was not able to boot because one timer was not used, hence not defined in the DT. I don't know if that could be the case for this platform but I prefer to keep thing going smoothly and return from init even if that lead to a kernel hang. Of course, the errors must be displayed (pr_warn, pr_err, pr_notice, etc ...). >> >>> + clk_disable_unprepare(clk); >>> +out_unmap: >>> + iounmap(base); >>> + WARN(ret, "ARM System timer register failed (%d)\n", ret); pr_warn Thanks -- Daniel
2015-03-27 9:36 GMT+01:00 Daniel Lezcano <daniel.lezcano@linaro.org>: > On 03/26/2015 09:19 PM, Maxime Coquelin wrote: >> >> Hi Daniel, >> >> Thanks for the review. Please find my answers below. >> >> 2015-03-26 10:50 GMT+01:00 Daniel Lezcano <daniel.lezcano@linaro.org>: >>> >>> On 03/12/2015 10:55 PM, Maxime Coquelin wrote: >>>> >>>> >>>> From: Maxime Coquelin <mcoquelin.stm32@gmail.com> >>>> >>>> This patch adds clocksource support for ARMv7-M's System timer, >>>> also known as SysTick. >>>> >>>> Signed-off-by: Maxime Coquelin <mcoquelin.stm32@gmail.com> >>> >>> >>> >>> Hi Maxime, >>> >>> the driver looks good. Three comments below. >>> >>> -- Daniel >>> >>> > > [ ... ] > > >>>> +static void __init system_timer_of_register(struct device_node *np) >>>> +{ >>>> + struct clk *clk; >>>> + void __iomem *base; >>>> + u32 rate = 0; >>>> + int ret; >>>> + >>>> + base = of_iomap(np, 0); >>>> + if (!base) { >>>> + pr_warn("system-timer: invalid base address\n"); >>>> + return; >>>> + } >>>> + >>>> + clk = of_clk_get(np, 0); >>>> + if (!IS_ERR(clk)) { >>>> + ret = clk_prepare_enable(clk); >>>> + if (ret) { >>>> + clk_put(clk); >>>> + goto out_unmap; >>>> + } >>>> + >>>> + rate = clk_get_rate(clk); >>>> + } >>>> + >>>> + /* If no clock found, try to get clock-frequency property */ >>>> + if (!rate) { >>>> + ret = of_property_read_u32(np, "clock-frequency", >>>> &rate); >>>> + if (ret) >>>> + goto out_unmap; >>> >>> >>> >>> Shouldn't be 'goto out_clk_disable' ? >> >> >> No, because I assumed !rate means we failed to get the clock. >> Actually, clk_get_rate could return 0, so relying on rate value is not >> safe. >> >> I propose to get clock-frequency property if IS_ERR(clk). >> >> Is it fine for you? > > > Why not invert the conditions ? If the 'clock-frequency' is specified in the > DT then it overrides the clk_get_rate(). So the resulting code will be: > > ret = of_property_read_u32(np, "clock-frequency", &rate); > if (ret) { > clk = of_clk_get(np, 0); > if (IS_ERR(clk)) > goto out_unmap; > > ret = clk_prepare_enable(clk); > if (ret) > goto out_clk_put; > > rate = clk_get_rate(clk); > if (!rate) > goto out_clk_unprepare; > > } Ok, it looks sensible. I will do this in next version. > > > >>>> + } >>>> + >>>> + writel_relaxed(SYSTICK_LOAD_RELOAD_MASK, base + SYST_RVR); >>>> + writel_relaxed(SYST_CSR_ENABLE, base + SYST_CSR); >>>> + >>>> + ret = clocksource_mmio_init(base + SYST_CVR, "arm_system_timer", >>>> rate, >>>> + 200, 24, clocksource_mmio_readl_down); >>>> + if (ret) { >>>> + pr_err("failed to init clocksource (%d)\n", ret); >>>> + goto out_clk_disable; >>>> + } >>>> + >>>> + pr_info("ARM System timer initialized as clocksource\n"); >>>> + >>>> + return; >>>> + >>>> +out_clk_disable: >>>> + if (!IS_ERR(clk)) >>> >>> >>> >>> Why do you need this check ? >> >> >> To handle the case were no clock was found, but a clk-frequency value >> was provided. >> >>> >>> It isn't missing a clk_put ? >> >> >> Right, thanks for spotting this. >> >> I wonder if it makes sense to implement the error path. >> If we fail to initialize the clocksource, the system will be unusable. >> >> Maybe I should just perform a BUG_ON() in the error cases, as most of >> the other clocksource drivers do. >> What is your view? > > > I prefer to not BUG_ON in the init functions because it already happen that > drivers were bugging at init time and when a driver was reused on another > platform with several timers available, the board was not able to boot > because one timer was not used, hence not defined in the DT. I don't know if > that could be the case for this platform but I prefer to keep thing going > smoothly and return from init even if that lead to a kernel hang. Of course, > the errors must be displayed (pr_warn, pr_err, pr_notice, etc ...). Ok, let's keep the error path, that's much cleaner indeed. > >>> >>>> + clk_disable_unprepare(clk); >>>> +out_unmap: >>>> + iounmap(base); >>>> + WARN(ret, "ARM System timer register failed (%d)\n", ret); > > > pr_warn Sure, will fix. Thanks, Maxime > > Thanks > > -- Daniel > > > -- > <http://www.linaro.org/> Linaro.org │ Open source software for ARM SoCs > > Follow Linaro: <http://www.facebook.com/pages/Linaro> Facebook | > <http://twitter.com/#!/linaroorg> Twitter | > <http://www.linaro.org/linaro-blog/> Blog > -- To unsubscribe from this list: send the line "unsubscribe linux-gpio" 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/drivers/clocksource/Kconfig b/drivers/clocksource/Kconfig index 1c2506f..b82e58b 100644 --- a/drivers/clocksource/Kconfig +++ b/drivers/clocksource/Kconfig @@ -134,6 +134,13 @@ config CLKSRC_ARM_GLOBAL_TIMER_SCHED_CLOCK help Use ARM global timer clock source as sched_clock +config ARMV7M_SYSTICK + bool + select CLKSRC_OF if OF + select CLKSRC_MMIO + help + This options enables support for the ARMv7M system timer unit + config ATMEL_PIT select CLKSRC_OF if OF def_bool SOC_AT91SAM9 || SOC_SAMA5 diff --git a/drivers/clocksource/Makefile b/drivers/clocksource/Makefile index 752d5c7..1c9a643 100644 --- a/drivers/clocksource/Makefile +++ b/drivers/clocksource/Makefile @@ -44,6 +44,7 @@ obj-$(CONFIG_MTK_TIMER) += mtk_timer.o obj-$(CONFIG_ARM_ARCH_TIMER) += arm_arch_timer.o obj-$(CONFIG_ARM_GLOBAL_TIMER) += arm_global_timer.o +obj-$(CONFIG_ARMV7M_SYSTICK) += armv7m_systick.o obj-$(CONFIG_CLKSRC_METAG_GENERIC) += metag_generic.o obj-$(CONFIG_ARCH_HAS_TICK_BROADCAST) += dummy_timer.o obj-$(CONFIG_ARCH_KEYSTONE) += timer-keystone.o diff --git a/drivers/clocksource/armv7m_systick.c b/drivers/clocksource/armv7m_systick.c new file mode 100644 index 0000000..23d8249 --- /dev/null +++ b/drivers/clocksource/armv7m_systick.c @@ -0,0 +1,78 @@ +/* + * Copyright (C) Maxime Coquelin 2015 + * Author: Maxime Coquelin <mcoquelin.stm32@gmail.com> + * License terms: GNU General Public License (GPL), version 2 + */ + +#include <linux/kernel.h> +#include <linux/clocksource.h> +#include <linux/clockchips.h> +#include <linux/of.h> +#include <linux/of_address.h> +#include <linux/clk.h> +#include <linux/bitops.h> + +#define SYST_CSR 0x00 +#define SYST_RVR 0x04 +#define SYST_CVR 0x08 +#define SYST_CALIB 0x0c + +#define SYST_CSR_ENABLE BIT(0) + +#define SYSTICK_LOAD_RELOAD_MASK 0x00FFFFFF + +static void __init system_timer_of_register(struct device_node *np) +{ + struct clk *clk; + void __iomem *base; + u32 rate = 0; + int ret; + + base = of_iomap(np, 0); + if (!base) { + pr_warn("system-timer: invalid base address\n"); + return; + } + + clk = of_clk_get(np, 0); + if (!IS_ERR(clk)) { + ret = clk_prepare_enable(clk); + if (ret) { + clk_put(clk); + goto out_unmap; + } + + rate = clk_get_rate(clk); + } + + /* If no clock found, try to get clock-frequency property */ + if (!rate) { + ret = of_property_read_u32(np, "clock-frequency", &rate); + if (ret) + goto out_unmap; + } + + writel_relaxed(SYSTICK_LOAD_RELOAD_MASK, base + SYST_RVR); + writel_relaxed(SYST_CSR_ENABLE, base + SYST_CSR); + + ret = clocksource_mmio_init(base + SYST_CVR, "arm_system_timer", rate, + 200, 24, clocksource_mmio_readl_down); + if (ret) { + pr_err("failed to init clocksource (%d)\n", ret); + goto out_clk_disable; + } + + pr_info("ARM System timer initialized as clocksource\n"); + + return; + +out_clk_disable: + if (!IS_ERR(clk)) + clk_disable_unprepare(clk); +out_unmap: + iounmap(base); + WARN(ret, "ARM System timer register failed (%d)\n", ret); +} + +CLOCKSOURCE_OF_DECLARE(arm_systick, "arm,armv7m-systick", + system_timer_of_register);