Date: Fri, 11 Mar 2016 03:41:37 +0000
From: Marc Zyngier <marc.zyngier@arm.com>
To: Stefan Agner <stefan@agner.ch>
Cc: shawnguo@kernel.org, mturquette@baylibre.com, sboyd@codeaurora.org,
        kernel@pengutronix.de, sergeimir@emcraft.com, tglx@linutronix.de,
        jason@lakedaemon.net, robh+dt@kernel.org, pawel.moll@arm.com,
        mark.rutland@arm.com, ijc+devicetree@hellion.org.uk,
        galak@codeaurora.org, devicetree@vger.kernel.org,
        linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org,
        linux-clk@vger.kernel.org
Subject: Re: [PATCH 01/18] irqchip: vf610-gpc: add Vybrid GPC IRQ controller
Message-ID: <20160311034137.169f22ae@arm.com>
In-Reply-To: <1457576219-7971-2-git-send-email-stefan@agner.ch>
References: <1457576219-7971-1-git-send-email-stefan@agner.ch>
	<1457576219-7971-2-git-send-email-stefan@agner.ch>
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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.

> +	.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?

> +	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...

> +
> +	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.

Thanks,

	M.
-- 
Jazz is not dead. It just smells funny.