Re: [PATCH v4 04/10] irqchip/sun6i-r: Add wakeup support

[Samuel Holland]

On 1/14/21 3:44 PM, Marc Zyngier wrote:
> On Tue, 12 Jan 2021 05:59:44 +0000,
> Samuel Holland <samuel@xxxxxxxxxxxx> wrote:
>>
>> Maintain bitmaps of wake-enabled IRQs and mux inputs, and program them
>> to the hardware during the syscore phase of suspend and shutdown. Then
>> restore the original set of enabled IRQs (only the NMI) during resume.
>>
>> This serves two purposes. First, it lets power management firmware
>> running on the ARISC coprocessor know which wakeup sources Linux wants
>> to have enabled. That way, it can avoid turning them off when it shuts
>> down the remainder of the clock tree. Second, it preconfigures the
>> coprocessor's interrupt controller, so the firmware's wakeup logic
>> is as simple as waiting for an interrupt to arrive.
>>
>> The suspend/resume logic is not conditional on PM_SLEEP because it is
>> identical to the init/shutdown logic. Wake IRQs may be enabled during
>> shutdown to allow powering the board back on. As an example, see
>> commit a5c5e50cce9d ("Input: gpio-keys - add shutdown callback").
>>
>> Signed-off-by: Samuel Holland <samuel@xxxxxxxxxxxx>
>> ---
>>  drivers/irqchip/irq-sun6i-r.c | 107 ++++++++++++++++++++++++++++++++--
>>  1 file changed, 101 insertions(+), 6 deletions(-)
>>
>> diff --git a/drivers/irqchip/irq-sun6i-r.c b/drivers/irqchip/irq-sun6i-r.c
>> index d04d067423f4..a1b58c98d6ca 100644
>> --- a/drivers/irqchip/irq-sun6i-r.c
>> +++ b/drivers/irqchip/irq-sun6i-r.c
>> @@ -39,6 +39,7 @@
>>   * set of 128 mux bits. This requires a second set of top-level registers.
>>   */
>>  
>> +#include <linux/bitmap.h>
>>  #include <linux/interrupt.h>
>>  #include <linux/irq.h>
>>  #include <linux/irqchip.h>
>> @@ -46,6 +47,7 @@
>>  #include <linux/of.h>
>>  #include <linux/of_address.h>
>>  #include <linux/of_irq.h>
>> +#include <linux/syscore_ops.h>
>>  
>>  #include <dt-bindings/interrupt-controller/arm-gic.h>
>>  
>> @@ -67,8 +69,17 @@
>>  #define SUN6I_NR_DIRECT_IRQS		16
>>  #define SUN6I_NR_MUX_BITS		128
>>  
>> +struct sun6i_r_intc_variant {
>> +	u32		first_mux_irq;
>> +	u32		nr_mux_irqs;
>> +	u32		mux_valid[BITS_TO_U32(SUN6I_NR_MUX_BITS)];
>> +};
>> +
>>  static void __iomem *base;
>>  static irq_hw_number_t nmi_hwirq;
>> +static DECLARE_BITMAP(wake_irq_enabled, SUN6I_NR_TOP_LEVEL_IRQS);
>> +static DECLARE_BITMAP(wake_mux_enabled, SUN6I_NR_MUX_BITS);
>> +static DECLARE_BITMAP(wake_mux_valid, SUN6I_NR_MUX_BITS);
>>  
>>  static void sun6i_r_intc_ack_nmi(void)
>>  {
>> @@ -145,6 +156,21 @@ static int sun6i_r_intc_nmi_set_irqchip_state(struct irq_data *data,
>>  	return irq_chip_set_parent_state(data, which, state);
>>  }
>>  
>> +static int sun6i_r_intc_irq_set_wake(struct irq_data *data, unsigned int on)
>> +{
>> +	unsigned long offset_from_nmi = data->hwirq - nmi_hwirq;
>> +
>> +	if (offset_from_nmi < SUN6I_NR_DIRECT_IRQS)
>> +		assign_bit(offset_from_nmi, wake_irq_enabled, on);
>> +	else if (test_bit(data->hwirq, wake_mux_valid))
>> +		assign_bit(data->hwirq, wake_mux_enabled, on);
>> +	else
>> +		/* Not wakeup capable. */
>> +		return -EPERM;
>> +
>> +	return 0;
>> +}
>> +
>>  static struct irq_chip sun6i_r_intc_nmi_chip = {
>>  	.name			= "sun6i-r-intc",
>>  	.irq_ack		= sun6i_r_intc_nmi_ack,
>> @@ -154,8 +180,19 @@ static struct irq_chip sun6i_r_intc_nmi_chip = {
>>  	.irq_set_affinity	= irq_chip_set_affinity_parent,
>>  	.irq_set_type		= sun6i_r_intc_nmi_set_type,
>>  	.irq_set_irqchip_state	= sun6i_r_intc_nmi_set_irqchip_state,
>> -	.flags			= IRQCHIP_SET_TYPE_MASKED |
>> -				  IRQCHIP_SKIP_SET_WAKE,
>> +	.irq_set_wake		= sun6i_r_intc_irq_set_wake,
>> +	.flags			= IRQCHIP_SET_TYPE_MASKED,
>> +};
>> +
>> +static struct irq_chip sun6i_r_intc_wakeup_chip = {
>> +	.name			= "sun6i-r-intc",
>> +	.irq_mask		= irq_chip_mask_parent,
>> +	.irq_unmask		= irq_chip_unmask_parent,
>> +	.irq_eoi		= irq_chip_eoi_parent,
>> +	.irq_set_affinity	= irq_chip_set_affinity_parent,
>> +	.irq_set_type		= irq_chip_set_type_parent,
>> +	.irq_set_wake		= sun6i_r_intc_irq_set_wake,
>> +	.flags			= IRQCHIP_SET_TYPE_MASKED,
> 
> Worth implementing irq_get/set_irqchip_state() using the _parent
> helper, I guess.

This is the same situation as the previous patch. Assuming it is safe to
rely on the behavior of the top-level functions, adding the callbacks
here would be redundant.

Cheers,
Samuel

> Thanks,
> 
> 	M.
>