[PATCH 2/2] Adding support for the plat-mxc cpuidle driver to mach-mx5. Tested on i.MX51 Babbage board with ARM core running at 800Mhz. Idle OS ARM core power before patch = ~400mW. Idle OS ARM core power after patch = ~1.25mW.

[linux@arm.linux.org.uk (Russell King - ARM Linux)]

> Subject: [PATCH 2/2] Adding support for the plat-mxc cpuidle driver to
>         mach-mx5. Tested on i.MX51 Babbage board with ARM core running
>         at 800Mhz. Idle OS ARM core power before patch = ~400mW. Idle
>         OS ARM core power after patch = ~1.25mW.

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On Thu, Aug 25, 2011 at 09:33:15PM -0500, Robert Lee wrote:
> Signed-off-by: Robert Lee <rob.lee@linaro.org>
> ---
>  arch/arm/mach-mx5/Kconfig                |    4 ++
>  arch/arm/mach-mx5/include/mach/cpuidle.h |   45 ++++++++++++++++++++++++++++++
>  arch/arm/mach-mx5/system.c               |   42 ++++++++++++++++++++++++++++
>  3 files changed, 91 insertions(+), 0 deletions(-)
>  create mode 100644 arch/arm/mach-mx5/include/mach/cpuidle.h
> 
> diff --git a/arch/arm/mach-mx5/Kconfig b/arch/arm/mach-mx5/Kconfig
> index b4e7c58..1672cfe 100644
> --- a/arch/arm/mach-mx5/Kconfig
> +++ b/arch/arm/mach-mx5/Kconfig
> @@ -19,6 +19,7 @@ config SOC_IMX50
>  	select ARCH_MXC_IOMUX_V3
>  	select ARCH_MXC_AUDMUX_V2
>  	select ARCH_HAS_CPUFREQ
> +	select ARCH_HAS_CPUIDLE
>  	select ARCH_MX5
>  	select ARCH_MX50
>  
> @@ -30,6 +31,7 @@ config	SOC_IMX51
>  	select ARCH_MXC_IOMUX_V3
>  	select ARCH_MXC_AUDMUX_V2
>  	select ARCH_HAS_CPUFREQ
> +	select ARCH_HAS_CPUIDLE
>  	select ARCH_MX5
>  
>  config	SOC_IMX53
> @@ -38,9 +40,11 @@ config	SOC_IMX53
>  	select ARM_L1_CACHE_SHIFT_6
>  	select MXC_TZIC
>  	select ARCH_MXC_IOMUX_V3
> +	select ARCH_HAS_CPUIDLE
>  	select ARCH_MX5
>  	select ARCH_MX53
>  
> +
>  if ARCH_MX50_SUPPORTED
>  #comment "i.MX50 machines:"
>  
> diff --git a/arch/arm/mach-mx5/include/mach/cpuidle.h b/arch/arm/mach-mx5/include/mach/cpuidle.h
> new file mode 100644
> index 0000000..6c37963
> --- /dev/null
> +++ b/arch/arm/mach-mx5/include/mach/cpuidle.h
> @@ -0,0 +1,45 @@
> +/*
> + * 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.
> + */
> +
> +#ifndef __ARCH_ARM_PLAT_MXC_CPUIDLE_H__
> +#define __ARCH_ARM_PLAT_MXC_CPUIDLE_H__
> +
> +
> +/* CPUIDLE state parameters: name, description, exit_latency (us)
> + * exit_latencies were tested using i.MX51 running at 160MHz P-state
> + * for worst case latencies as to not cause a pm_qos violation when
> + * running at lower speeds.
> + */
> +#define MXC_CPUIDLE_TABLE {\
> +MXC_X_MACRO(POWERED_CLOCKED, "idle cpu clocked, powered.", 12),\
> +MXC_X_MACRO(POWERED_NOCLOCK, "idle cpu powered, unclocked.", 14),\
> +MXC_X_MACRO(NOPOWER_NOCLOCK, "idle cpu unpowered, unclocked.", 20),\
> +MXC_X_MACRO(MXC_NUM_CPUIDLE_STATES, "", -1)}
> +
> +#define MXC_X_MACRO(a, b, c) a
> +enum MXC_CPUIDLE_STATE_NAME MXC_CPUIDLE_TABLE;
> +#undef MXC_X_MACRO
> +
> +struct imx_cpuidle_params {
> +	unsigned int latency;
> +};
> +
> +void imx_cpu_do_idle(int cpuidle_state_num);
> +
> +/* if you want to override the mach level params at the board level,
> + * define MXC_OVERRIDE_CPUIDLE_PARAMS and pass your board level paramaters
> + * into the imx_cpuidle_board_params function */
> +
> +/* #define MXC_OVERRIDE_DEFAULT_CPUIDLE_PARAMS */
> +
> +#ifdef CONFIG_MXC_CPUIDLE
> +extern void imx_cpuidle_board_params(struct imx_cpuidle_params *cpuidle_params);
> +#else
> +inline void imx_cpuidle_board_params(struct imx_cpuidle_params *cpuidle_params)
> +{}
> +#endif
> +
> +#endif /* #ifndef __ARCH_ARM_PLAT_MXC_CPUIDLE_H__ */
> diff --git a/arch/arm/mach-mx5/system.c b/arch/arm/mach-mx5/system.c
> index 76ae8dc..6ff938d 100644
> --- a/arch/arm/mach-mx5/system.c
> +++ b/arch/arm/mach-mx5/system.c
> @@ -12,9 +12,16 @@
>   */
>  #include <linux/platform_device.h>
>  #include <linux/io.h>
> +#include <linux/clk.h>
> +#include <asm/proc-fns.h>
>  #include <mach/hardware.h>
> +#include <mach/mxc.h>
> +#include <mach/cpuidle.h>
>  #include "crm_regs.h"
>  
> +static int arch_idle_mode = WAIT_UNCLOCKED_POWER_OFF;
> +static struct clk *gpc_dvfs_clk;
> +
>  /* set cpu low power mode before WFI instruction. This function is called
>    * mx5 because it can be used for mx50, mx51, and mx53.*/
>  void mx5_cpu_lp_set(enum mxc_cpu_pwr_mode mode)
> @@ -82,3 +89,38 @@ void mx5_cpu_lp_set(enum mxc_cpu_pwr_mode mode)
>  		__raw_writel(empgc1, MXC_SRPG_EMPGC1_SRPGCR);
>  	}
>  }
> +
> +void imx_cpu_do_idle(int cpuidle_state_num)
> +{
> +
> +	int local_arch_idle_mode = arch_idle_mode;
> +
> +	if (gpc_dvfs_clk == NULL)
> +		gpc_dvfs_clk = clk_get(NULL, "gpc_dvfs_clk");
> +	/* gpc clock is needed for SRPG */
> +	clk_enable(gpc_dvfs_clk);
> +
> +	/* convert MXC_CPUIDLE_STATE_NAME to mxc_cpu_pwr_mode. */
> +	switch (cpuidle_state_num) {
> +	case POWERED_CLOCKED:
> +		local_arch_idle_mode = WAIT_CLOCKED;
> +		break;
> +	case POWERED_NOCLOCK:
> +		local_arch_idle_mode = WAIT_UNCLOCKED;
> +		break;
> +	case NOPOWER_NOCLOCK:
> +		local_arch_idle_mode = WAIT_UNCLOCKED_POWER_OFF;
> +		break;
> +	default:
> +		break;
> +	}
> +	/* prepare registers for upcoming idle mode */
> +	mx5_cpu_lp_set(local_arch_idle_mode);
> +
> +	/* enter wfi state which on i.MX5 can trigger */
> +	cpu_do_idle();
> +
> +	clk_disable(gpc_dvfs_clk);
> +}
> +
> +
> -- 
> 1.7.1
> 
> 
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