linux-kernel - Re: [PATCHv2] ARM: imx: Add support for low power suspend on MX51.

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Message-ID: <20101109222239.GI6017@pengutronix.de>
Date:	Tue, 9 Nov 2010 23:22:39 +0100
From:	Sascha Hauer <s.hauer@...gutronix.de>
To:	Dinh.Nguyen@...escale.com
Cc:	linux-kernel@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
	linux@....linux.org.uk, u.kleine-koenig@...gutronix.de,
	amit.kucheria@...onical.com, eric@...rea.com
Subject: Re: [PATCHv2] ARM: imx: Add support for low power suspend on MX51.

On Fri, Nov 05, 2010 at 11:49:32AM -0500, Dinh.Nguyen@...escale.com wrote:
> From: Dinh Nguyen <Dinh.Nguyen@...escale.com>
> 
> Adds initial low power suspend functionality to MX51.
> Supports "mem" and "standby" modes.
> 
> Signed-off-by: Dinh Nguyen <Dinh.Nguyen@...escale.com>
> ---
>  arch/arm/mach-mx5/Makefile           |    1 +
>  arch/arm/mach-mx5/pm.c               |   86 ++++++++++++++++++++++++++++++++++
>  arch/arm/plat-mxc/include/mach/mxc.h |    1 +
>  3 files changed, 88 insertions(+), 0 deletions(-)
>  create mode 100644 arch/arm/mach-mx5/pm.c
> 
> diff --git a/arch/arm/mach-mx5/Makefile b/arch/arm/mach-mx5/Makefile
> index 462f177..25b44d1 100644
> --- a/arch/arm/mach-mx5/Makefile
> +++ b/arch/arm/mach-mx5/Makefile
> @@ -5,6 +5,7 @@
>  # Object file lists.
>  obj-y   := cpu.o mm.o clock-mx51.o devices.o
>  
> +obj-$(CONFIG_PM) += pm.o
>  obj-$(CONFIG_CPU_FREQ_IMX)    += cpu_op-mx51.o
>  obj-$(CONFIG_MACH_MX51_BABBAGE) += board-mx51_babbage.o
>  obj-$(CONFIG_MACH_MX51_3DS) += board-mx51_3ds.o
> diff --git a/arch/arm/mach-mx5/pm.c b/arch/arm/mach-mx5/pm.c
> new file mode 100644
> index 0000000..2639125
> --- /dev/null
> +++ b/arch/arm/mach-mx5/pm.c
> @@ -0,0 +1,86 @@
> +/*
> + *  Copyright (C) 2010 Freescale Semiconductor, Inc. All Rights Reserved.
> + *
> + * The code contained herein is licensed under the GNU General Public
> + * License. You may obtain a copy of the GNU General Public License
> + * Version 2 or later at the following locations:
> + *
> + * http://www.opensource.org/licenses/gpl-license.html
> + * http://www.gnu.org/copyleft/gpl.html
> + */
> +#include <linux/suspend.h>
> +#include <asm/mach/map.h>
> +#include <mach/system.h>
> +#include "crm_regs.h"
> +
> +/* set cpu low power mode before WFI instruction */
> +static void mxc_cpu_lp_set(suspend_state_t state)
> +{
> +	u32 plat_lpc, arm_srpgcr, ccm_clpcr;
> +
> +	/* always allow platform to issue a deep sleep mode request */
> +	plat_lpc = __raw_readl(MXC_CORTEXA8_PLAT_LPC) &
> +		~(MXC_CORTEXA8_PLAT_LPC_DSM);

You clear this bit unconditionally here...

> +	ccm_clpcr = __raw_readl(MXC_CCM_CLPCR) & ~(MXC_CCM_CLPCR_LPM_MASK);
> +	arm_srpgcr = __raw_readl(MXC_SRPG_ARM_SRPGCR) & ~(MXC_SRPGCR_PCR);
> +
> +	plat_lpc |= MXC_CORTEXA8_PLAT_LPC_DSM
> +		    | MXC_CORTEXA8_PLAT_LPC_DBG_DSM;

...and set the same bit here again.

> +
> +	switch (state) {
> +	case PM_SUSPEND_MEM:
> +		ccm_clpcr |= (0x2 << MXC_CCM_CLPCR_LPM_OFFSET);
> +		ccm_clpcr |= (0x3 << MXC_CCM_CLPCR_STBY_COUNT_OFFSET);
> +		ccm_clpcr |= MXC_CCM_CLPCR_VSTBY;
> +		ccm_clpcr |= MXC_CCM_CLPCR_SBYOS;
> +		break;
> +	case PM_SUSPEND_STANDBY:
> +		ccm_clpcr |= (0x1 << MXC_CCM_CLPCR_LPM_OFFSET);
> +		ccm_clpcr &= ~MXC_CCM_CLPCR_VSTBY;
> +		ccm_clpcr &= ~MXC_CCM_CLPCR_SBYOS;
> +		break;
> +	}
> +
> +	arm_srpgcr |= MXC_SRPGCR_PCR;

The same with this bit.

> +
> +	__raw_writel(plat_lpc, MXC_CORTEXA8_PLAT_LPC);
> +	__raw_writel(ccm_clpcr, MXC_CCM_CLPCR);
> +	__raw_writel(arm_srpgcr, MXC_SRPG_ARM_SRPGCR);
> +}
> +
> +static int mx5_suspend_enter(suspend_state_t state)
> +{
> +	switch (state) {
> +	case PM_SUSPEND_MEM:
> +		mxc_cpu_lp_set(state);
> +		break;
> +	case PM_SUSPEND_STANDBY:
> +		mxc_cpu_lp_set(state);
> +		break;
> +	default:
> +		return -EINVAL;
> +	}

Can you inline the code of mxc_cpu_lp_set() here? This duplicate
switch/case really does not look good.

> +
> +	if (tzic_enable_wake(0) != 0)
> +		return -EAGAIN;
> +	cpu_do_idle();
> +	return 0;
> +}
> +
> +static int mx5_pm_valid(suspend_state_t state)
> +{
> +	return (state > PM_SUSPEND_ON && state <= PM_SUSPEND_MAX);
> +}
> +
> +static const struct platform_suspend_ops mx5_suspend_ops = {
> +	.valid = mx5_pm_valid,
> +	.enter = mx5_suspend_enter,
> +};
> +
> +static int __init mx5_pm_init(void)
> +{
> +	if (cpu_is_mx51())
> +		suspend_set_ops(&mx5_suspend_ops);
> +	return 0;
> +}
> +device_initcall(mx5_pm_init);
> diff --git a/arch/arm/plat-mxc/include/mach/mxc.h b/arch/arm/plat-mxc/include/mach/mxc.h
> index a42c720..dafacfd 100644
> --- a/arch/arm/plat-mxc/include/mach/mxc.h
> +++ b/arch/arm/plat-mxc/include/mach/mxc.h
> @@ -37,6 +37,7 @@
>  
>  #ifndef __ASSEMBLY__
>  extern unsigned int __mxc_cpu_type;
> +int tzic_enable_wake(int is_idle);
>  #endif
>  
>  #ifdef CONFIG_ARCH_MX1
> -- 
> 1.6.0.4
> 
> 
> 

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