lkml.org 
[lkml]   [2015]   [Apr]   [9]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    /
    Date
    From
    SubjectRe: [PATCH v6 04/15] clocksource/drivers: Add ARM System timer driver
    On 04/07/2015 06:30 PM, Maxime Coquelin wrote:
    > This patch adds clocksource support for ARMv7-M's System timer,
    > also known as SysTick.
    >
    > Tested-by: Chanwoo Choi <cw00.choi@samsung.com>
    > Signed-off-by: Maxime Coquelin <mcoquelin.stm32@gmail.com>

    Acked-by: Daniel Lezcano <daniel.lezcano@linaro.org>

    > ---
    > drivers/clocksource/Kconfig | 7 ++++
    > drivers/clocksource/Makefile | 1 +
    > drivers/clocksource/armv7m_systick.c | 79 ++++++++++++++++++++++++++++++++++++
    > 3 files changed, 87 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..addfd2c
    > --- /dev/null
    > +++ b/drivers/clocksource/armv7m_systick.c
    > @@ -0,0 +1,79 @@
    > +/*
    > + * 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 = NULL;
    > + void __iomem *base;
    > + u32 rate;
    > + int ret;
    > +
    > + base = of_iomap(np, 0);
    > + if (!base) {
    > + pr_warn("system-timer: invalid base address\n");
    > + return;
    > + }
    > +
    > + 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_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);
    > + if (clk)
    > + goto out_clk_disable;
    > + else
    > + goto out_unmap;
    > + }
    > +
    > + pr_info("ARM System timer initialized as clocksource\n");
    > +
    > + return;
    > +
    > +out_clk_disable:
    > + clk_disable_unprepare(clk);
    > +out_clk_put:
    > + clk_put(clk);
    > +out_unmap:
    > + iounmap(base);
    > + pr_warn("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



    \
     
     \ /
      Last update: 2015-04-09 13:21    [W:2.367 / U:0.620 seconds]
    ©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site