Date:   Thu, 22 Mar 2018 14:35:08 +0000
From:   Marc Zyngier <marc.zyngier@....com>
To:     Alexandre Belloni <alexandre.belloni@...tlin.com>
Cc:     Jason Cooper <jason@...edaemon.net>,
        Thomas Gleixner <tglx@...utronix.de>,
        Thomas Petazzoni <thomas.petazzoni@...tlin.com>,
        <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v2 2/2] irqchip: Add a driver for the Microsemi Ocelot controller

On Thu, 22 Mar 2018 13:55:42 +0000,
Alexandre Belloni wrote:

Hi Alexandre,

> 
> The Microsemi Ocelot SoC has a pretty simple IRQ controller in its ICPU
> block. Add a driver for it.
> 
> Signed-off-by: Alexandre Belloni <alexandre.belloni@...tlin.com>
> ---
> changes since v1:
>  - removed license in favor of SPDX tag
>  - reworked style as suggested by Thomas
> 
>  drivers/irqchip/Kconfig           |   5 ++
>  drivers/irqchip/Makefile          |   1 +
>  drivers/irqchip/irq-mscc-ocelot.c | 109 ++++++++++++++++++++++++++++++++++++++
>  3 files changed, 115 insertions(+)
>  create mode 100644 drivers/irqchip/irq-mscc-ocelot.c
> 
> diff --git a/drivers/irqchip/Kconfig b/drivers/irqchip/Kconfig
> index d913aec85109..0270797765f9 100644
> --- a/drivers/irqchip/Kconfig
> +++ b/drivers/irqchip/Kconfig
> @@ -286,6 +286,11 @@ config IRQ_MXS
>  	select IRQ_DOMAIN
>  	select STMP_DEVICE
>  
> +config MSCC_OCELOT_IRQ
> +	bool
> +	select IRQ_DOMAIN
> +	select GENERIC_IRQ_CHIP
> +
>  config MVEBU_GICP
>  	bool
>  
> diff --git a/drivers/irqchip/Makefile b/drivers/irqchip/Makefile
> index d27e3e3619e0..63d7bb434c33 100644
> --- a/drivers/irqchip/Makefile
> +++ b/drivers/irqchip/Makefile
> @@ -72,6 +72,7 @@ obj-$(CONFIG_ARCH_SA1100)		+= irq-sa11x0.o
>  obj-$(CONFIG_INGENIC_IRQ)		+= irq-ingenic.o
>  obj-$(CONFIG_IMX_GPCV2)			+= irq-imx-gpcv2.o
>  obj-$(CONFIG_PIC32_EVIC)		+= irq-pic32-evic.o
> +obj-$(CONFIG_MSCC_OCELOT_IRQ)		+= irq-mscc-ocelot.o
>  obj-$(CONFIG_MVEBU_GICP)		+= irq-mvebu-gicp.o
>  obj-$(CONFIG_MVEBU_ICU)			+= irq-mvebu-icu.o
>  obj-$(CONFIG_MVEBU_ODMI)		+= irq-mvebu-odmi.o
> diff --git a/drivers/irqchip/irq-mscc-ocelot.c b/drivers/irqchip/irq-mscc-ocelot.c
> new file mode 100644
> index 000000000000..c71094de3cbd
> --- /dev/null
> +++ b/drivers/irqchip/irq-mscc-ocelot.c
> @@ -0,0 +1,109 @@
> +// SPDX-License-Identifier: (GPL-2.0 OR MIT)
> +/*
> + * Microsemi Ocelot IRQ controller driver
> + *
> + * Copyright (c) 2017 Microsemi Corporation
> + */
> +#include <linux/bitops.h>
> +#include <linux/irq.h>
> +#include <linux/of_address.h>
> +#include <linux/of_irq.h>
> +#include <linux/irqchip.h>
> +#include <linux/irqchip/chained_irq.h>
> +#include <linux/interrupt.h>
> +
> +#define ICPU_CFG_INTR_INTR_STICKY	0x10
> +#define ICPU_CFG_INTR_INTR_ENA		0x18
> +#define ICPU_CFG_INTR_INTR_ENA_CLR	0x1c
> +#define ICPU_CFG_INTR_INTR_ENA_SET	0x20
> +#define ICPU_CFG_INTR_DST_INTR_IDENT(x)	(0x38 + 0x4 * (x))
> +#define ICPU_CFG_INTR_INTR_TRIGGER(x)	(0x5c + 0x4 * (x))
> +
> +#define OCELOT_NR_IRQ 24
> +
> +static void ocelot_irq_unmask(struct irq_data *data)
> +{
> +	struct irq_chip_generic *gc = irq_data_get_irq_chip_data(data);
> +	struct irq_chip_type *ct = irq_data_get_chip_type(data);
> +	unsigned int mask = data->mask;
> +	u32 val;
> +
> +	irq_gc_lock(gc);
> +	val = irq_reg_readl(gc, ICPU_CFG_INTR_INTR_TRIGGER(0)) |
> +	      irq_reg_readl(gc, ICPU_CFG_INTR_INTR_TRIGGER(1));
> +	if (!(val & mask))
> +		irq_reg_writel(gc, mask, ICPU_CFG_INTR_INTR_STICKY);
> +
> +	*ct->mask_cache &= ~mask;
> +	irq_reg_writel(gc, mask, ICPU_CFG_INTR_INTR_ENA_SET);
> +	irq_gc_unlock(gc);
> +}
> +
> +static void ocelot_irq_handler(struct irq_desc *desc)
> +{
> +	struct irq_chip *chip = irq_desc_get_chip(desc);
> +	struct irq_domain *d = irq_desc_get_handler_data(desc);
> +	struct irq_chip_generic *gc = irq_get_domain_generic_chip(d, 0);
> +	u32 reg = irq_reg_readl(gc, ICPU_CFG_INTR_DST_INTR_IDENT(0));
> +
> +	chained_irq_enter(chip, desc);
> +
> +	while (reg) {
> +		u32 hwirq = __fls(reg);
> +
> +		generic_handle_irq(irq_find_mapping(d, hwirq));
> +		reg &= ~(BIT(hwirq));
> +	}
> +
> +	chained_irq_exit(chip, desc);
> +}
> +
> +static int __init ocelot_irq_init(struct device_node *node,
> +				  struct device_node *parent)
> +{
> +	struct irq_domain *domain;
> +	struct irq_chip_generic *gc;
> +	int parent_irq, ret;
> +
> +	domain = irq_domain_add_linear(node, OCELOT_NR_IRQ,
> +				       &irq_generic_chip_ops, NULL);
> +	if (!domain) {
> +		pr_err("%s: unable to add irq domain\n", node->name);
> +		return -ENOMEM;
> +	}
> +
> +	ret = irq_alloc_domain_generic_chips(domain, OCELOT_NR_IRQ, 1,
> +					     "icpu", handle_level_irq,
> +					     0, 0, 0);
> +	if (ret) {
> +		pr_err("%s: unable to alloc irq domain gc\n", node->name);
> +		return ret;

You're now leaking the allocated domain.

> +	}
> +
> +	gc = irq_get_domain_generic_chip(domain, 0);
> +	gc->reg_base = of_iomap(node, 0);
> +	if (!gc->reg_base) {
> +		pr_err("%s: unable to map resource\n", node->name);
> +		return -ENOMEM;

And here the chip.

> +	}
> +
> +	gc->chip_types[0].regs.ack = ICPU_CFG_INTR_INTR_STICKY;
> +	gc->chip_types[0].regs.mask = ICPU_CFG_INTR_INTR_ENA_CLR;
> +	gc->chip_types[0].chip.irq_ack = irq_gc_ack_set_bit;
> +	gc->chip_types[0].chip.irq_mask = irq_gc_mask_set_bit;
> +	gc->chip_types[0].chip.irq_unmask = ocelot_irq_unmask;
> +
> +	/* Mask and ack all interrupts */
> +	irq_reg_writel(gc, 0, ICPU_CFG_INTR_INTR_ENA);
> +	irq_reg_writel(gc, 0xffffffff, ICPU_CFG_INTR_INTR_STICKY);
> +
> +	parent_irq = irq_of_parse_and_map(node, 0);
> +	if (!parent_irq)

and here the ioremap space. You could also check that parent is
non-NULL early on, just in case...

> +		return -EINVAL;
> +
> +	irq_set_chained_handler_and_data(parent_irq, ocelot_irq_handler,
> +					 domain);
> +
> +	return 0;
> +}
> +IRQCHIP_DECLARE(ocelot_icpu, "mscc,ocelot-icpu-intr", ocelot_irq_init);
> -- 
> 2.16.2
> 

If you rework the error handling quickly, I'll queue this for 4.17. It
is quite refreshing to see an irqchip with only 3 functions...

Thanks,

	M.

-- 
Jazz is not dead, it just smell funny.

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