[PATCH RFC] ARM: imx: avic: set low-power interrupt mask for imx25

[Shawn Guo]

On Fri, Feb 09, 2018 at 01:43:23PM +0100, Martin Kaiser wrote:
> imx25 contains two registers (LPIMR0 and 1) to define which interrupts
> are enabled in low-power mode. As of today, those two registers are
> configured to enable all interrupts. Before going to low-power mode, the
> AVIC's INTENABLEH and INTENABLEL registers are configured to enable only
> those interrupts which are used as wakeup sources.
> 
> It turned out that this approach is not sufficient if we want the imx25
> to go into stop mode during suspend-to-ram. (Stop mode is the low-power
> mode that consumes the least power. The peripheral master clock is
> switched off in this mode). For stop mode to work, the LPIMR0 and 1
> registers have to be configured with the set of interrupts that are
> allowed in low-power mode. Fortunately, the bits in the LPIMR registers
> are assigned to the same interrups as the bits in INTENABLEH and
> INTENABLEL. However, LPIMR uses 1 to mask an interrupt whereas the
> INTENABLE registers use 1 to enable an interrupt.
> 
> This patch sets the LPIMR registers to the inverted bitmask of the
> INTENABLE registers during suspend and goes back to "all interrupts
> masked" when we wake up again. We also make this the default at startup.
> 
> As far as I know, the other supported imx architectures have no similar
> mechanism. Since the LPIMR registers are part of the CCM module, we
> query the device tree for an imx25 ccm node in order to detect if we're
> running on imx25.
> 
> Signed-off-by: Martin Kaiser <martin at kaiser.cx>
> ---
> 
> Dear all,
> 
> could you have a look at this first draft? The approach to detect imx25
> looks a bit hackish, I'd appreciate your suggestions how to do this
> properly.
> 
> Thanks & best regards,
> 
>    Martin
> 
>  arch/arm/mach-imx/avic.c | 24 +++++++++++++++++++++++-
>  1 file changed, 23 insertions(+), 1 deletion(-)
> 
> diff --git a/arch/arm/mach-imx/avic.c b/arch/arm/mach-imx/avic.c
> index 1afccae..bd6d3f2 100644
> --- a/arch/arm/mach-imx/avic.c
> +++ b/arch/arm/mach-imx/avic.c
> @@ -22,6 +22,7 @@
>  #include <linux/irqdomain.h>
>  #include <linux/io.h>
>  #include <linux/of.h>
> +#include <linux/of_address.h>
>  #include <asm/mach/irq.h>
>  #include <asm/exception.h>
>  
> @@ -51,7 +52,10 @@
>  
>  #define AVIC_NUM_IRQS 64
>  
> -static void __iomem *avic_base;
> +#define MX25_CCM_LPIMR0	0x68
> +#define MX25_CCM_LPIMR1	0x6C
> +
> +static void __iomem *avic_base, *mx25_ccm_base;

Keep avic_base line untouched, and add a new one for mx25_ccm_base.

>  static struct irq_domain *domain;
>  
>  #ifdef CONFIG_FIQ
> @@ -93,6 +97,11 @@ static void avic_irq_suspend(struct irq_data *d)
>  
>  	avic_saved_mask_reg[idx] = imx_readl(avic_base + ct->regs.mask);
>  	imx_writel(gc->wake_active, avic_base + ct->regs.mask);

Have a newline here.

> +	if (mx25_ccm_base) {
> +		u8 offs = d->hwirq < AVIC_NUM_IRQS / 2 ?
> +			MX25_CCM_LPIMR0 : MX25_CCM_LPIMR1;
> +		imx_writel(~gc->wake_active, mx25_ccm_base + offs);
> +	}
>  }
>  
>  static void avic_irq_resume(struct irq_data *d)
> @@ -102,6 +111,11 @@ static void avic_irq_resume(struct irq_data *d)
>  	int idx = d->hwirq >> 5;
>  
>  	imx_writel(avic_saved_mask_reg[idx], avic_base + ct->regs.mask);

Ditto

Shawn

> +	if (mx25_ccm_base) {
> +		u8 offs = d->hwirq < AVIC_NUM_IRQS / 2 ?
> +			MX25_CCM_LPIMR0 : MX25_CCM_LPIMR1;
> +		imx_writel(0xffffffff, mx25_ccm_base + offs);
> +	}
>  }
>  
>  #else
> @@ -158,6 +172,14 @@ void __init mxc_init_irq(void __iomem *irqbase)
>  
>  	avic_base = irqbase;
>  
> +	np = of_find_compatible_node(NULL, NULL, "fsl,imx25-ccm");
> +	mx25_ccm_base = of_iomap(np, 0);
> +
> +	if (mx25_ccm_base) {
> +		imx_writel(0xffffffff, mx25_ccm_base + MX25_CCM_LPIMR0);
> +		imx_writel(0xffffffff, mx25_ccm_base + MX25_CCM_LPIMR1);
> +	}
> +
>  	/* put the AVIC into the reset value with
>  	 * all interrupts disabled
>  	 */
> -- 
> 2.1.4
>