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Date: Mon, 03 Jun 2013 16:03:35 +0200
From: Daniel Lezcano <daniel.lezcano@...aro.org>
To: Michal Simek <michal.simek@...inx.com>
CC: linux-kernel@...r.kernel.org, Michal Simek <monstr@...str.eu>,
Arnd Bergmann <arnd@...db.de>,
linux-arm-kernel@...ts.infradead.org,
Josh Cartwright <josh.cartwright@...com>,
Steffen Trumtrar <s.trumtrar@...gutronix.de>,
Rob Herring <robherring2@...il.com>,
Peter Crosthwaite <peter.crosthwaite@...inx.com>,
"Rafael J. Wysocki" <rjw@...k.pl>, linux-pm@...r.kernel.org
Subject: Re: [PATCH v3] arm: zynq: Add cpuidle support
On 06/03/2013 03:40 PM, Michal Simek wrote:
> Add support for cpuidle.
>
> Signed-off-by: Michal Simek <michal.simek@...inx.com>
> ---
> Changes in v3:
> - Move driver to drivers/cpuidle/
> - Check zynq compatible string suggested by Arnd
> - Use zynq_ function prefix because of multiplatform kernel
> - Incorporate comments from Daniel Lezcano
> - Rebase on the top of git://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm.git linux-next
>
> Changes in v2:
> - Fix file header
>
> Changes in v1:
> - It was the part of Zynq core changes
> https://patchwork.kernel.org/patch/2342511/
>
> drivers/cpuidle/Kconfig | 6 +++
> drivers/cpuidle/Makefile | 1 +
> drivers/cpuidle/cpuidle-zynq.c | 100 +++++++++++++++++++++++++++++++++++++++++
> 3 files changed, 107 insertions(+)
> create mode 100644 drivers/cpuidle/cpuidle-zynq.c
>
> diff --git a/drivers/cpuidle/Kconfig b/drivers/cpuidle/Kconfig
> index c4cc27e..8272a08 100644
> --- a/drivers/cpuidle/Kconfig
> +++ b/drivers/cpuidle/Kconfig
> @@ -39,4 +39,10 @@ config CPU_IDLE_CALXEDA
> help
> Select this to enable cpuidle on Calxeda processors.
>
> +config CPU_IDLE_ZYNQ
> + bool "CPU Idle Driver for Xilinx Zynq processors"
> + depends on ARCH_ZYNQ
> + help
> + Select this to enable cpuidle on Xilinx Zynq processors.
> +
> endif
> diff --git a/drivers/cpuidle/Makefile b/drivers/cpuidle/Makefile
> index 0d8bd55..8767a7b 100644
> --- a/drivers/cpuidle/Makefile
> +++ b/drivers/cpuidle/Makefile
> @@ -7,3 +7,4 @@ obj-$(CONFIG_ARCH_NEEDS_CPU_IDLE_COUPLED) += coupled.o
>
> obj-$(CONFIG_CPU_IDLE_CALXEDA) += cpuidle-calxeda.o
> obj-$(CONFIG_ARCH_KIRKWOOD) += cpuidle-kirkwood.o
> +obj-$(CONFIG_CPU_IDLE_ZYNQ) += cpuidle-zynq.o
> diff --git a/drivers/cpuidle/cpuidle-zynq.c b/drivers/cpuidle/cpuidle-zynq.c
> new file mode 100644
> index 0000000..afe6af3
> --- /dev/null
> +++ b/drivers/cpuidle/cpuidle-zynq.c
> @@ -0,0 +1,100 @@
> +/*
> + * Copyright (C) 2012-2013 Xilinx
> + *
> + * CPU idle support for Xilinx Zynq
> + *
> + * based on arch/arm/mach-at91/cpuidle.c
> + *
> + * This file is licensed under the terms of the GNU General Public
> + * License version 2. This program is licensed "as is" without any
> + * warranty of any kind, whether express or implied.
> + *
> + * The cpu idle uses wait-for-interrupt and RAM self refresh in order
> + * to implement two idle states -
> + * #1 wait-for-interrupt
> + * #2 wait-for-interrupt and RAM self refresh
> + */
Please check you headers, it seems you are including unused headers.
> +#include <linux/kernel.h>
> +#include <linux/init.h>
> +#include <linux/platform_device.h>
> +#include <linux/cpuidle.h>
> +#include <linux/io.h>
^^^^^
> +#include <linux/export.h>
^^^^^
> +#include <linux/clockchips.h>
^^^^^
> +#include <linux/cpu_pm.h>
> +#include <linux/clk.h>
^^^^
> +#include <linux/err.h>
> +#include <linux/of.h>
> +#include <asm/proc-fns.h>
> +#include <asm/cpuidle.h>
> +
> +#define ZYNQ_MAX_STATES 2
> +
> +static DEFINE_PER_CPU(struct cpuidle_device, zynq_cpuidle_device);
see below.
> +
> +/* Actual code that puts the SoC in different idle states */
> +static int zynq_enter_idle(struct cpuidle_device *dev,
> + struct cpuidle_driver *drv, int index)
Indentation.
> +{
> + /* Devices must be stopped here */
> + cpu_pm_enter();
> +
> + /* Add code for DDR self refresh start */
> + cpu_do_idle();
> +
> + /* Add code for DDR self refresh stop */
> + cpu_pm_exit();
> +
> + return index;
> +}
> +
> +static struct cpuidle_driver zynq_idle_driver = {
> + .name = "zynq_idle",
> + .owner = THIS_MODULE,
> + .states = {
> + ARM_CPUIDLE_WFI_STATE,
> + {
> + .enter = zynq_enter_idle,
> + .exit_latency = 10,
> + .target_residency = 10000,
> + .flags = CPUIDLE_FLAG_TIME_VALID,
> + CPUIDLE_FLAG_TIMER_STOP,
> + .name = "RAM_SR",
> + .desc = "WFI and RAM Self Refresh",
> + },
> + },
> + .safe_state_index = 0,
> + .state_count = ZYNQ_MAX_STATES,
> +};
> +
> +/* Initialize CPU idle by registering the idle states */
> +static int zynq_init_cpuidle(void)
> +{
> + unsigned int cpu;
> + struct cpuidle_device *device;
> + int ret;
> +
> + if (!of_machine_is_compatible("xlnx,zynq-7000"))
> + return -ENODEV;
> +
> + ret = cpuidle_register_driver(&zynq_idle_driver);
> + if (ret) {
> + pr_err("%s: Driver registration failed\n", __func__);
> + return ret;
> + }
> +
> + for_each_possible_cpu(cpu) {
> + device = &per_cpu(zynq_cpuidle_device, cpu);
> + device->cpu = cpu;
> + ret = cpuidle_register_device(device);
> + if (ret) {
> + pr_err("%s: Device registration failed\n", __func__);
> + return ret;
> + }
> + }
> +
> + pr_info("Xilinx Zynq CpuIdle Driver started\n");
Hi Michal,
actually you can replace this code by
cpuidle_register(&zynq_idle_driver, NULL);
and remove the zynq_cpuidle_device.
The framework will take care of registering the driver and the devices.
> + return 0;
> +}
> +module_init(zynq_init_cpuidle);
Do you really want it as module ?
Thanks
-- Daniel
--
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