[PATCH 1/2] Adding platform level cpuidle driver for i.MX SoCs.

[Sascha Hauer]

On Thu, Aug 25, 2011 at 09:33:14PM -0500, Robert Lee wrote:
> Signed-off-by: Robert Lee <rob.lee at linaro.org>
> ---
> --- /dev/null
> +++ b/arch/arm/plat-mxc/cpuidle.c
> @@ -0,0 +1,112 @@
> +/*
> + * 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.
> + */
> +
> +#include <linux/io.h>
> +#include <linux/cpuidle.h>
> +#include <asm/proc-fns.h>
> +#include <mach/hardware.h>
> +#include <mach/system.h>
> +#include <mach/cpuidle.h>
> +
> +
> +#ifndef MXC_OVERRIDE_DEFAULT_CPUIDLE_PARAMS

Either there is a possibility to overwrite the cpuidle parameters
or there is none, but we don't need a define for this. I'm not
convinced we need this possibility at all though.

> +
> +#define MXC_X_MACRO(a, b, c) {c}
> +static struct imx_cpuidle_params default_cpuidle_params[] = \
> +	MXC_CPUIDLE_TABLE;
> +#undef MXC_X_MACRO

Hell! This is one of the worst unnecessary preprocessor abuses I've ever
seen. Do not show this in public again.

> +
> +static struct imx_cpuidle_params *imx_cpuidle_params = default_cpuidle_params;
> +
> +#else
> +
> +static struct imx_cpuidle_params *imx_cpuidle_params;
> +
> +#endif
> +
> +
> +
> +/* in case you want to override the mach level params at the board level */
> +void imx_cpuidle_board_params(struct imx_cpuidle_params *cpuidle_params)
> +{
> +	imx_cpuidle_params = cpuidle_params;
> +}
> +
> +static int imx_enter_idle(struct cpuidle_device *dev,
> +			       struct cpuidle_state *state)
> +{
> +	struct timeval before, after;
> +	int idle_time, i;
> +
> +	/* We only need to pass an index to the mach level so here we
> +	 * find the index of the name contained in the cpuidle_state
> +	 * to pass. */
> +	for (i = 0; i < MXC_NUM_CPUIDLE_STATES && i < CPUIDLE_STATE_MAX; i++)

A define for MXC_NUM_CPUIDLE_STATES looks wrong, it is not constant for
different SoCs.

> +		if (state == &dev->states[i])
> +			break;
> +
> +	local_irq_disable();
> +	local_fiq_disable();
> +
> +	do_gettimeofday(&before);
> +
> +	imx_cpu_do_idle(i);

We are currently working on running a single image on as many SoCs we
can. Take a step back and imagine what the linker says when it finds
6 different functions named imx_cpu_do_idle()

> +
> +	do_gettimeofday(&after);
> +
> +	local_fiq_enable();
> +	local_irq_enable();
> +
> +	idle_time = (after.tv_sec - before.tv_sec) * USEC_PER_SEC +
> +			(after.tv_usec - before.tv_usec);
> +
> +	return idle_time;
> +}
> +
> +static struct cpuidle_driver imx_cpuidle_driver = {
> +	.name =         "imx_idle",
> +	.owner =        THIS_MODULE,
> +};
> +
> +static DEFINE_PER_CPU(struct cpuidle_device, imx_cpuidle_device);
> +
> +static int __init imx_cpuidle_init(void)
> +{
> +	struct cpuidle_device *device;
> +	int i;
> +
> +	#define MXC_X_MACRO(a, b, c) #a
> +	char *mxc_cpuidle_state_name[] = MXC_CPUIDLE_TABLE;
> +	#undef MXC_X_MACRO
> +
> +	#define MXC_X_MACRO(a, b, c) b
> +	char *mxc_cpuidle_state_desc[] = MXC_CPUIDLE_TABLE;
> +	#undef MXC_X_MACRO
> +
> +	if (imx_cpuidle_params == NULL)
> +		return -ENODEV;
> +
> +	cpuidle_register_driver(&imx_cpuidle_driver);
> +
> +	device = &per_cpu(imx_cpuidle_device, smp_processor_id());
> +	device->state_count = MXC_NUM_CPUIDLE_STATES;
> +
> +	for (i = 0; i < MXC_NUM_CPUIDLE_STATES && i < CPUIDLE_STATE_MAX; i++) {
> +		device->states[i].enter = imx_enter_idle;
> +		device->states[i].exit_latency = imx_cpuidle_params[i].latency;
> +		device->states[i].flags = CPUIDLE_FLAG_TIME_VALID;
> +		strcpy(device->states[i].name, mxc_cpuidle_state_name[i]);
> +		strcpy(device->states[i].desc, mxc_cpuidle_state_desc[i]);
> +	}
> +
> +	if (cpuidle_register_device(device)) {
> +		printk(KERN_ERR "imx_cpuidle_init: Failed registering\n");
> +		return -ENODEV;
> +	}
> +	return 0;

This should really be a platform driver.


I'm glad I'm on holiday for the next two weeks.

Sascha

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