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:0.169 / U:1.976 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site