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Message-ID: <5513D64A.7060702@linaro.org>
Date: Thu, 26 Mar 2015 10:50:02 +0100
From: Daniel Lezcano <daniel.lezcano@...aro.org>
To: Maxime Coquelin <mcoquelin.stm32@...il.com>,
u.kleine-koenig@...gutronix.de, afaerber@...e.de,
geert@...ux-m68k.org, Rob Herring <robh+dt@...nel.org>,
Philipp Zabel <p.zabel@...gutronix.de>,
Linus Walleij <linus.walleij@...aro.org>,
Arnd Bergmann <arnd@...db.de>, stefan@...er.ch,
pmeerw@...erw.net, pebolle@...cali.nl
CC: Jonathan Corbet <corbet@....net>, Pawel Moll <pawel.moll@....com>,
Mark Rutland <mark.rutland@....com>,
Ian Campbell <ijc+devicetree@...lion.org.uk>,
Kumar Gala <galak@...eaurora.org>,
Russell King <linux@....linux.org.uk>,
Thomas Gleixner <tglx@...utronix.de>,
Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
Jiri Slaby <jslaby@...e.cz>,
Andrew Morton <akpm@...ux-foundation.org>,
"David S. Miller" <davem@...emloft.net>,
Mauro Carvalho Chehab <mchehab@....samsung.com>,
Joe Perches <joe@...ches.com>, Antti Palosaari <crope@....fi>,
Tejun Heo <tj@...nel.org>, Will Deacon <will.deacon@....com>,
Nikolay Borisov <Nikolay.Borisov@....com>,
Rusty Russell <rusty@...tcorp.com.au>,
Kees Cook <keescook@...omium.org>,
Michal Marek <mmarek@...e.cz>, linux-doc@...r.kernel.org,
linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
devicetree@...r.kernel.org, linux-gpio@...r.kernel.org,
linux-serial@...r.kernel.org, linux-arch@...r.kernel.org,
linux-api@...r.kernel.org
Subject: Re: [PATCH v3 04/15] clocksource: Add ARM System timer driver
On 03/12/2015 10:55 PM, Maxime Coquelin wrote:
> From: Maxime Coquelin <mcoquelin.stm32@...il.com>
>
> This patch adds clocksource support for ARMv7-M's System timer,
> also known as SysTick.
>
> Signed-off-by: Maxime Coquelin <mcoquelin.stm32@...il.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@...il.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);
>
--
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