[PATCH 01/18] irqchip: vf610-gpc: add Vybrid GPC IRQ controller

Stefan Agner
2016-03-11T18:11:43Z

Hi Marc,

On 2016-03-10 19:41, Marc Zyngier wrote:
> On Wed, 9 Mar 2016 18:16:42 -0800
> Stefan Agner <stefan@agner.ch> wrote:
>
> Hi Stefan,
>
>> This patch introduces a driver for Vybrids GPC (Global Power
>> Controller). Vybrids GPC IP is simpler than the one found in
>> i.MX 6: There is no power gating control (GPC) and the GPC INTC
>> does not need to clear IRQ masks for an interrupt to get routed
>> to the GIC (the mask only applys for wake-up control).
>>
>> Signed-off-by: Stefan Agner <stefan@agner.ch>
>> ---
>> drivers/irqchip/Makefile | 1 +
>> drivers/irqchip/irq-vf610-gpc.c | 138 ++++++++++++++++++++++++++++++++++++++++
>> 2 files changed, 139 insertions(+)
>> create mode 100644 drivers/irqchip/irq-vf610-gpc.c
>>
>> diff --git a/drivers/irqchip/Makefile b/drivers/irqchip/Makefile
>> index 18caacb..0a77ac6 100644
>> --- a/drivers/irqchip/Makefile
>> +++ b/drivers/irqchip/Makefile
>> @@ -45,6 +45,7 @@ obj-$(CONFIG_TS4800_IRQ) += irq-ts4800.o
>> obj-$(CONFIG_XTENSA) += irq-xtensa-pic.o
>> obj-$(CONFIG_XTENSA_MX) += irq-xtensa-mx.o
>> obj-$(CONFIG_IRQ_CROSSBAR) += irq-crossbar.o
>> +obj-$(CONFIG_SOC_VF610) += irq-vf610-gpc.o
>> obj-$(CONFIG_SOC_VF610) += irq-vf610-mscm-ir.o
>> obj-$(CONFIG_BCM7038_L1_IRQ) += irq-bcm7038-l1.o
>> obj-$(CONFIG_BCM7120_L2_IRQ) += irq-bcm7120-l2.o
>> diff --git a/drivers/irqchip/irq-vf610-gpc.c b/drivers/irqchip/irq-vf610-gpc.c
>> new file mode 100644
>> index 0000000..2c6a043
>> --- /dev/null
>> +++ b/drivers/irqchip/irq-vf610-gpc.c
>> @@ -0,0 +1,138 @@
>> +/*
>> + * Copyright (C) 2016 Toradex AG
>> + * Author: Stefan Agner <stefan@agner.ch>
>> + *
>> + * This program is free software; you can redistribute it and/or modify
>> + * it under the terms of the GNU General Public License version 2 as
>> + * published by the Free Software Foundation.
>> + *
>> + *
>> + * The GPC (General Power Controller) irqchip driver takes care of the
>> + * interrupt wakeup functionality.
>> + *
>> + * o All peripheral interrupts of the Vybrid SoC can be used as wakeup
>> + * source from STOP mode. In LPSTOP mode however, the GPC is unpowered
>> + * too and cannot be used to as a wakeup source. The WKPU (Wakeup Unit)
>> + * is responsible for wakeups from LPSTOP modes.
>> + */
>> +
>> +#include <linux/cpu_pm.h>
>> +#include <linux/io.h>
>> +#include <linux/irq.h>
>> +#include <linux/irqchip.h>
>> +#include <linux/irqdomain.h>
>> +#include <linux/mfd/syscon.h>
>> +#include <dt-bindings/interrupt-controller/arm-gic.h>
>> +#include <linux/of.h>
>> +#include <linux/of_address.h>
>> +#include <linux/slab.h>
>> +#include <linux/regmap.h>
>> +
>> +#define IMR_NUM 4
>> +#define VF610_GPC_IMR1 0x044
>> +#define VF610_GPC_MAX_IRQS (IMR_NUM * 32)
>> +
>> +static void __iomem *gpc_base;
>> +
>> +static int vf610_gpc_irq_set_wake(struct irq_data *d, unsigned int on)
>> +{
>> + unsigned int idx = d->hwirq / 32;
>> + void __iomem *reg_imr = gpc_base + VF610_GPC_IMR1 + (idx * 4);
>> + u32 mask = 1 << d->hwirq % 32;
>> +
>> + if (on)
>> + writel_relaxed(readl_relaxed(reg_imr) & ~mask, reg_imr);
>> + else
>> + writel_relaxed(readl_relaxed(reg_imr) | mask, reg_imr);
>> +
>> + /*
>> + * Do *not* call into the parent, as the GIC doesn't have any
>> + * wake-up facility...
>> + */
>> + return 0;
>> +}
>> +
>> +static struct irq_chip vf610_gpc_chip = {
>> + .name = "vf610-gpc",
>> + .irq_mask = irq_chip_mask_parent,
>> + .irq_unmask = irq_chip_unmask_parent,
>> + .irq_enable = irq_chip_enable_parent,
>> + .irq_disable = irq_chip_disable_parent,
>
> Any reason why you are providing enable/disable methods? This driver
> seems to be GIC specific (various comments in the code), but the GIC
> doesn't implement those.

There is another IRQ controller between the CPU's IRQ controller and the
peripherals: the MSCM Interrupt Router
(drivers/irqchip/irq-vf610-mscm-ir.c).

This router allows to select to which CPU an interrupt gets routed
(VF6xx variants of Vybrid with a Cortex-A5 and Cortex-M4 core).

>
>> + .irq_eoi = irq_chip_eoi_parent,
>> + .irq_retrigger = irq_chip_retrigger_hierarchy,
>> + .irq_set_wake = vf610_gpc_irq_set_wake,
>> +};
>> +
>> +static int vf610_gpc_domain_alloc(struct irq_domain *domain, unsigned int virq,
>> + unsigned int nr_irqs, void *arg)
>> +{
>> + int i;
>> + irq_hw_number_t hwirq;
>> + struct irq_fwspec *fwspec = arg;
>> + struct irq_fwspec parent_fwspec;
>> +
>> + if (!irq_domain_get_of_node(domain->parent))
>> + return -EINVAL;
>> +
>> + if (fwspec->param_count != 2)
>> + return -EINVAL;
>> +
>> + hwirq = fwspec->param[0];
>> + for (i = 0; i < nr_irqs; i++)
>> + irq_domain_set_hwirq_and_chip(domain, virq + i, hwirq + i,
>> + &vf610_gpc_chip, NULL);
>> +
>> + parent_fwspec = *fwspec;
>
> Now I'm confused. The next irqchip in the hierarchy cannot be the GIC,
> because that's the wrong fwspec format (the GIC expect 3 parameters).
> Glancing at patch #2, I can see that this points to the mscm, so maybe
> it is that the comments are just wrong?

The above should explain that...

So with this driver the domain hierarchy stacks 3 IRQ controllers

GPC -> MSCM-IR -> NVIC/GIC (depending on CPU)

>
>> + parent_fwspec.fwnode = domain->parent->fwnode;
>> + return irq_domain_alloc_irqs_parent(domain, virq, nr_irqs,
>> + &parent_fwspec);
>> +}
>> +
>> +static int vf610_gpc_domain_translate(struct irq_domain *d,
>> + struct irq_fwspec *fwspec,
>> + unsigned long *hwirq,
>> + unsigned int *type)
>> +{
>> + if (WARN_ON(fwspec->param_count < 2))
>> + return -EINVAL;
>> + *hwirq = fwspec->param[0];
>> + *type = fwspec->param[1] & IRQ_TYPE_SENSE_MASK;
>> + return 0;
>> +}
>> +
>> +static const struct irq_domain_ops gpc_irq_domain_ops = {
>> + .translate = vf610_gpc_domain_translate,
>> + .alloc = vf610_gpc_domain_alloc,
>> + .free = irq_domain_free_irqs_common,
>> +};
>> +
>> +static int __init vf610_gpc_of_init(struct device_node *node,
>> + struct device_node *parent)
>> +{
>> + struct irq_domain *domain, *domain_parent;
>> + int i;
>> +
>> + domain_parent = irq_find_host(parent);
>> + if (!domain_parent) {
>> + pr_err("vf610_gpc: interrupt-parent not found\n");
>> + return -EINVAL;
>> + }
>> +
>> + gpc_base = of_io_request_and_map(node, 0, "gpc");
>> + if (WARN_ON(!gpc_base))
>> + return PTR_ERR(gpc_base);
>
> If gpc_base is NULL, PTR_ERR(NULL) returns 0. Probably not what you
> want here...
>

Hm, of_io_request_and_map actually returns a ERR_PTR, hence WARN_ON is
not appropriate as it is used here.

Will remove that and replace with

if (IS_ERR(gpc_base))
return PTR_ERR(gpc_base);

>> +
>> + domain = irq_domain_add_hierarchy(domain_parent, 0, VF610_GPC_MAX_IRQS,
>> + node, &gpc_irq_domain_ops, NULL);
>> + if (!domain) {
>> + iounmap(gpc_base);
>> + return -ENOMEM;
>> + }
>> +
>> + /* Initially mask all interrupts for wakeup */
>> + for (i = 0; i < IMR_NUM; i++)
>> + writel_relaxed(~0, gpc_base + VF610_GPC_IMR1 + i * 4);
>> +
>> + return 0;
>> +}
>> +IRQCHIP_DECLARE(vf610_gpc, "fsl,vf610-gpc", vf610_gpc_of_init);
>
> It would be good to have some binding documentation as well.

Will add that

Thanks!

--
Stefan