Date:	Tue, 19 Feb 2013 10:03:32 +0900
From:	Simon Horman <horms@...ge.net.au>
To:	Magnus Damm <magnus.damm@...il.com>
Cc:	linux-kernel@...r.kernel.org, linux-sh@...r.kernel.org,
	benh@...nel.crashing.org, grant.likely@...retlab.ca,
	tglx@...utronix.de
Subject: Re: [PATCH] irqchip: Renesas INTC External IRQ pin driver

On Mon, Feb 18, 2013 at 11:28:34PM +0900, Magnus Damm wrote:
> From: Magnus Damm <damm@...nsource.se>
> 
> This patch adds a driver for external IRQ pins connected
> to the INTC block on recent SoCs from Renesas.
> 
> The INTC hardware block usually contains a rather wide
> range of features ranging from external IRQ pin handling
> to legacy interrupt controller support. On older SoCs
> the INTC is used as a general purpose interrupt controller
> both for external IRQ pins and on-chip devices.
> 
> On more recent ARM based SoCs with Cortex-A9 the main
> interrupt controller is the GIC, but IRQ trigger setup
> still need to happen in the INTC hardware block.
> 
> This driver implements the glue code needed to configure
> IRQ trigger and also handle mask/unmask and demux of
> external IRQ pins hooked up from the INTC to the GIC.
> 
> Tested on sh73a0 and r8a7779. The hardware varies quite
> a bit with SoC model, for instance register width and
> bitfield widths vary wildly. The driver requires one GIC
> SPI per external IRQ pin to operate.  Each driver instance
> will handle up to 8 external IRQ pins.
> 
> The SoCs using this driver are currently mainly used
> together with regular platform devices so this driver
> allows configuration via platform data to support things
> like static interrupt base address. DT support will
> be added incrementally in the not so distant future.
> 
> Signed-off-by: Magnus Damm <damm@...nsource.se>

Hi Magnus, Hi all,

I do not expect this code to go through the renesas tree.  However, in
order to provide a basis for work on renesas SoCs I have added this patch
to the topic/intc-external-irq topic branch in the reneas tree on
kernel.org and merged it into topic/all+next.

In other words, I am not picking this series up to merge it or add it to
linux-next, rather I am storing it for reference.


In the course of adding the branch I noticed a 3 whitespace warnings
from git. I have highlighted them below.

> ---
> 
>  drivers/irqchip/Kconfig                               |    4 
>  drivers/irqchip/Makefile                              |    1 
>  drivers/irqchip/irq-renesas-intc-irqpin.c             |  464 +++++++++++++++++
>  include/linux/platform_data/irq-renesas-intc-irqpin.h |   10 
>  4 files changed, 479 insertions(+)
> 
> --- 0001/drivers/irqchip/Kconfig
> +++ work/drivers/irqchip/Kconfig	2013-02-18 18:28:22.000000000 +0900
> @@ -25,6 +25,10 @@ config ARM_VIC_NR
>  	  The maximum number of VICs available in the system, for
>  	  power management.
>  
> +config RENESAS_INTC_IRQPIN
> +	bool
> +	select IRQ_DOMAIN
> +
>  config VERSATILE_FPGA_IRQ
>  	bool
>  	select IRQ_DOMAIN
> --- 0001/drivers/irqchip/Makefile
> +++ work/drivers/irqchip/Makefile	2013-02-18 18:28:22.000000000 +0900
> @@ -5,4 +5,5 @@ obj-$(CONFIG_ARCH_SUNXI)		+= irq-sunxi.o
>  obj-$(CONFIG_ARCH_SPEAR3XX)		+= spear-shirq.o
>  obj-$(CONFIG_ARM_GIC)			+= irq-gic.o
>  obj-$(CONFIG_ARM_VIC)			+= irq-vic.o
> +obj-$(CONFIG_RENESAS_INTC_IRQPIN)	+= irq-renesas-intc-irqpin.o
>  obj-$(CONFIG_VERSATILE_FPGA_IRQ)	+= irq-versatile-fpga.o
> --- /dev/null
> +++ work/drivers/irqchip/irq-renesas-intc-irqpin.c	2013-02-18 21:06:32.000000000 +0900
> @@ -0,0 +1,464 @@
> +/*
> + * Renesas INTC External IRQ Pin Driver
> + *
> + *  Copyright (C) 2013 Magnus Damm
> + *
> + * This program is free software; you can redistribute it and/or modify
> + * it under the terms of the GNU General Public License as published by
> + * the Free Software Foundation; either version 2 of the License
> + *
> + * This program is distributed in the hope that it will be useful,
> + * but WITHOUT ANY WARRANTY; without even the implied warranty of
> + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
> + * GNU General Public License for more details.
> + *
> + * You should have received a copy of the GNU General Public License
> + * along with this program; if not, write to the Free Software
> + * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
> + */
> +
> +#include <linux/init.h>
> +#include <linux/platform_device.h>
> +#include <linux/spinlock.h>
> +#include <linux/interrupt.h>
> +#include <linux/ioport.h>
> +#include <linux/io.h>
> +#include <linux/irq.h>
> +#include <linux/irqdomain.h>
> +#include <linux/err.h>
> +#include <linux/slab.h>
> +#include <linux/module.h>
> +#include <linux/platform_data/irq-renesas-intc-irqpin.h>
> +
> +#define INTC_IRQPIN_MAX 8 /* maximum 8 interrupts per driver instance */
> +
> +#define INTC_IRQPIN_REG_SENSE 0 /* ICRn */
> +#define INTC_IRQPIN_REG_PRIO 1 /* INTPRInn */
> +#define INTC_IRQPIN_REG_SOURCE 2 /* INTREQnn */
> +#define INTC_IRQPIN_REG_MASK 3 /* INTMSKnn */
> +#define INTC_IRQPIN_REG_CLEAR 4 /* INTMSKCLRnn */
> +#define INTC_IRQPIN_REG_NR 5
> +
> +/* INTC external IRQ PIN hardware register access:
> + *
> + * SENSE is read-write 32-bit with 2-bits or 4-bits per IRQ (*)
> + * PRIO is read-write 32-bit with 4-bits per IRQ (**)
> + * SOURCE is read-only 32-bit or 8-bit with 1-bit per IRQ (***)
> + * MASK is write-only 32-bit or 8-bit with 1-bit per IRQ (***)
> + * CLEAR is write-only 32-bit or 8-bit with 1-bit per IRQ (***)
> + *
> + * (*) May be accessed by more than one driver instance - lock needed
> + * (**) Read-modify-write access by one driver instance - lock needed
> + * (***) Accessed by one driver instance only - no locking needed
> + */
> +
> +struct intc_irqpin_iomem {
> +	void __iomem *iomem;
> +	unsigned long (*read)(void __iomem *iomem);
> +	void (*write)(void __iomem *iomem, unsigned long data);
> +	int width;
> +};  

git tells me there is trailing whitespace here.

> +
> +struct intc_irqpin_irq {
> +	int hw_irq;
> +	int irq;
> +	struct intc_irqpin_priv *p;
> +};  

And here.

> +
> +struct intc_irqpin_priv {
> +	struct intc_irqpin_iomem iomem[INTC_IRQPIN_REG_NR];
> +	struct intc_irqpin_irq irq[INTC_IRQPIN_MAX];
> +	struct renesas_intc_irqpin_config config;
> +	unsigned int number_of_irqs;
> +	struct platform_device *pdev;
> +	struct irq_chip irq_chip;
> +	struct irq_domain *irq_domain;
> +};
> +
> +static unsigned long intc_irqpin_read32(void __iomem *iomem)
> +{
> +	return ioread32(iomem);
> +}
> +
> +static unsigned long intc_irqpin_read8(void __iomem *iomem)
> +{
> +	return ioread8(iomem);
> +}
> +
> +static void intc_irqpin_write32(void __iomem *iomem, unsigned long data)
> +{
> +	iowrite32(data, iomem);
> +}
> +
> +static void intc_irqpin_write8(void __iomem *iomem, unsigned long data)
> +{
> +	iowrite8(data, iomem);
> +}
> +
> +static inline unsigned long intc_irqpin_read(struct intc_irqpin_priv *p,
> +					     int reg)
> +{
> +	struct intc_irqpin_iomem *i = &p->iomem[reg];
> +	return i->read(i->iomem);
> +}
> +
> +static inline void intc_irqpin_write(struct intc_irqpin_priv *p,
> +				     int reg, unsigned long data)
> +{
> +	struct intc_irqpin_iomem *i = &p->iomem[reg];
> +	i->write(i->iomem, data);
> +}
> +
> +static inline unsigned long intc_irqpin_hwirq_mask(struct intc_irqpin_priv *p,
> +						   int reg, int hw_irq)
> +{
> +	return BIT((p->iomem[reg].width - 1) - hw_irq);
> +}
> +
> +static inline void intc_irqpin_irq_write_hwirq(struct intc_irqpin_priv *p,
> +					       int reg, int hw_irq)
> +{
> +	intc_irqpin_write(p, reg, intc_irqpin_hwirq_mask(p, reg, hw_irq));
> +}
> +
> +static DEFINE_RAW_SPINLOCK(intc_irqpin_lock); /* only used by slow path */
> +
> +static void intc_irqpin_read_modify_write(struct intc_irqpin_priv *p,
> +					  int reg, int shift,
> +					  int width, int value)
> +{
> +	unsigned long flags;
> +	unsigned long tmp;
> +
> +	raw_spin_lock_irqsave(&intc_irqpin_lock, flags);
> +
> +	tmp = intc_irqpin_read(p, reg);
> +	tmp &= ~(((1 << width) - 1) << shift);
> +	tmp |= value << shift;
> +	intc_irqpin_write(p, reg, tmp);
> +
> +	raw_spin_unlock_irqrestore(&intc_irqpin_lock, flags);
> +}
> +
> +static void intc_irqpin_mask_unmask_prio(struct intc_irqpin_priv *p,
> +					 int irq, int do_mask)
> +{
> +	int bitfield_width = 4; /* PRIO assumed to have fixed bitfield width */
> +	int shift = (7 - irq) * bitfield_width; /* PRIO assumed to be 32-bit */
> +
> +	intc_irqpin_read_modify_write(p, INTC_IRQPIN_REG_PRIO,
> +				      shift, bitfield_width,
> +				      do_mask ? 0 : (1 << bitfield_width) - 1);
> +}
> +
> +static int intc_irqpin_set_sense(struct intc_irqpin_priv *p, int irq, int value)
> +{
> +	int bitfield_width = p->config.sense_bitfield_width;
> +	int shift = (7 - irq) * bitfield_width; /* SENSE assumed to be 32-bit */
> +
> +	dev_dbg(&p->pdev->dev, "sense irq = %d, mode = %d\n", irq, value);
> +
> +	if (value >= (1 << bitfield_width))
> +		return -EINVAL;
> +
> +	intc_irqpin_read_modify_write(p, INTC_IRQPIN_REG_SENSE, shift,
> +				      bitfield_width, value);
> +	return 0;
> +}
> +
> +static void intc_irqpin_dbg(struct intc_irqpin_irq *i, char *str)
> +{
> +	dev_dbg(&i->p->pdev->dev, "%s (%d:%d:%d)\n",
> +		str, i->irq, i->hw_irq,
> +		irq_find_mapping(i->p->irq_domain, i->hw_irq));
> +}
> +
> +static void intc_irqpin_irq_enable(struct irq_data *d)
> +{
> +	struct intc_irqpin_priv *p = irq_data_get_irq_chip_data(d);
> +	int hw_irq = irqd_to_hwirq(d);
> +
> +	intc_irqpin_dbg(&p->irq[hw_irq], "enable");
> +	intc_irqpin_irq_write_hwirq(p, INTC_IRQPIN_REG_CLEAR, hw_irq);
> +}
> +
> +static void intc_irqpin_irq_disable(struct irq_data *d)
> +{
> +	struct intc_irqpin_priv *p = irq_data_get_irq_chip_data(d);
> +	int hw_irq = irqd_to_hwirq(d);
> +
> +	intc_irqpin_dbg(&p->irq[hw_irq], "disable");
> +	intc_irqpin_irq_write_hwirq(p, INTC_IRQPIN_REG_MASK, hw_irq);
> +}
> +
> +static void intc_irqpin_irq_enable_force(struct irq_data *d)
> +{
> +	struct intc_irqpin_priv *p = irq_data_get_irq_chip_data(d);
> +	int irq = p->irq[irqd_to_hwirq(d)].irq;
> +
> +	intc_irqpin_irq_enable(d);
> +	irq_get_chip(irq)->irq_unmask(irq_get_irq_data(irq));
> +}
> +
> +static void intc_irqpin_irq_disable_force(struct irq_data *d)
> +{
> +	struct intc_irqpin_priv *p = irq_data_get_irq_chip_data(d);
> +	int irq = p->irq[irqd_to_hwirq(d)].irq;
> +
> +	irq_get_chip(irq)->irq_mask(irq_get_irq_data(irq));
> +	intc_irqpin_irq_disable(d);
> +}
> +
> +#define INTC_IRQ_SENSE_VALID 0x10
> +#define INTC_IRQ_SENSE(x) (x + INTC_IRQ_SENSE_VALID)
> +
> +static unsigned char intc_irqpin_sense[IRQ_TYPE_SENSE_MASK + 1] = {
> +	[IRQ_TYPE_EDGE_FALLING] = INTC_IRQ_SENSE(0x00),
> +	[IRQ_TYPE_EDGE_RISING] = INTC_IRQ_SENSE(0x01),
> +	[IRQ_TYPE_LEVEL_LOW] = INTC_IRQ_SENSE(0x02),
> +	[IRQ_TYPE_LEVEL_HIGH] = INTC_IRQ_SENSE(0x03),
> +	[IRQ_TYPE_EDGE_BOTH] = INTC_IRQ_SENSE(0x04),
> +};
> +
> +static int intc_irqpin_irq_set_type(struct irq_data *d, unsigned int type)
> +{
> +	unsigned char value = intc_irqpin_sense[type & IRQ_TYPE_SENSE_MASK];
> +	struct intc_irqpin_priv *p = irq_data_get_irq_chip_data(d);
> +
> +	if (!(value & INTC_IRQ_SENSE_VALID))
> +		return -EINVAL;
> +
> +	return intc_irqpin_set_sense(p, irqd_to_hwirq(d),
> +				     value ^ INTC_IRQ_SENSE_VALID);
> +}
> +
> +static irqreturn_t intc_irqpin_irq_handler(int irq, void *dev_id)
> +{
> +	struct intc_irqpin_irq *i = dev_id;
> +	struct intc_irqpin_priv *p = i->p;
> +	unsigned long bit;
> +
> +	intc_irqpin_dbg(i, "demux1");
> +	bit = intc_irqpin_hwirq_mask(p, INTC_IRQPIN_REG_SOURCE, i->hw_irq);
> +
> +	if (intc_irqpin_read(p, INTC_IRQPIN_REG_SOURCE) & bit) {
> +		intc_irqpin_write(p, INTC_IRQPIN_REG_SOURCE, ~bit);
> +		intc_irqpin_dbg(i, "demux2");
> +		generic_handle_irq(irq_find_mapping(p->irq_domain, i->hw_irq));
> +		return IRQ_HANDLED;
> +	}
> +	return IRQ_NONE;
> +}
> +
> +static int intc_irqpin_irq_domain_map(struct irq_domain *h, unsigned int virq,
> +				      irq_hw_number_t hw)
> +{
> +	struct intc_irqpin_priv *p = h->host_data;
> +
> +	intc_irqpin_dbg(&p->irq[hw], "map");
> +	irq_set_chip_data(virq, h->host_data);
> +	irq_set_chip_and_handler(virq, &p->irq_chip, handle_level_irq);
> +	set_irq_flags(virq, IRQF_VALID); /* kill me now */
> +	return 0;
> +}
> +
> +static struct irq_domain_ops intc_irqpin_irq_domain_ops = {
> +	.map	= intc_irqpin_irq_domain_map,
> +};
> +
> +static int intc_irqpin_probe(struct platform_device *pdev)
> +{
> +	struct renesas_intc_irqpin_config *pdata = pdev->dev.platform_data;
> +	struct intc_irqpin_priv *p;
> +	struct intc_irqpin_iomem *i;
> +	struct resource *io[INTC_IRQPIN_REG_NR];
> +	struct resource *irq;
> +	struct irq_chip *irq_chip;
> +	void (*enable_fn)(struct irq_data *d);
> +	void (*disable_fn)(struct irq_data *d);
> +	const char *name = dev_name(&pdev->dev);
> +	int ret;
> +	int k;
> +
> +	p = kzalloc(sizeof(*p), GFP_KERNEL);
> +	if (!p) {
> +		dev_err(&pdev->dev, "failed to allocate driver data\n");
> +		ret = -ENOMEM;
> +		goto err0;
> +	}
> +
> +	/* deal with driver instance configuration */
> +	if (pdata)
> +		memcpy(&p->config, pdata, sizeof(*pdata));
> +	if (!p->config.sense_bitfield_width)
> +		p->config.sense_bitfield_width = 4; /* default to 4 bits */
> +
> +	p->pdev = pdev;
> +	platform_set_drvdata(pdev, p);
> +
> +	/* get hold of manadatory IOMEM */
> +	for (k = 0; k < INTC_IRQPIN_REG_NR; k++) {
> +		io[k] = platform_get_resource(pdev, IORESOURCE_MEM, k);
> +		if (!io[k]) {
> +			dev_err(&pdev->dev, "not enough IOMEM resources\n");
> +			ret = -EINVAL;
> +			goto err1;
> +		}
> +	}
> +
> +	/* allow any number of IRQs between 1 and INTC_IRQPIN_MAX */
> +	for (k = 0; k < INTC_IRQPIN_MAX; k++) {
> +		irq = platform_get_resource(pdev, IORESOURCE_IRQ, k);
> +		if (!irq)
> +			break;
> +
> +		p->irq[k].hw_irq = k;
> +		p->irq[k].p = p;
> +		p->irq[k].irq = irq->start;
> +	}
> +
> +	p->number_of_irqs = k;
> +	if (p->number_of_irqs < 1) {
> +		dev_err(&pdev->dev, "not enough IRQ resources\n");
> +		ret = -EINVAL;
> +		goto err1;
> +	}
> +
> +	/* ioremap IOMEM and setup read/write callbacks */
> +	for (k = 0; k < INTC_IRQPIN_REG_NR; k++) {
> +		i = &p->iomem[k];
> +
> +		switch (resource_size(io[k])) {
> +		case 1:
> +			i->width = 8;
> +			i->read = intc_irqpin_read8;
> +			i->write = intc_irqpin_write8;
> +			break;
> +		case 4:
> +			i->width = 32;
> +			i->read = intc_irqpin_read32;
> +			i->write = intc_irqpin_write32;
> +			break;
> +		default:
> +			dev_err(&pdev->dev, "IOMEM size mismatch\n");
> +			ret = -EINVAL;
> +			goto err2;
> +		}
> +
> +		i->iomem = ioremap_nocache(io[k]->start, resource_size(io[k]));
> +		if (!i->iomem) {
> +			dev_err(&pdev->dev, "failed to remap IOMEM\n");
> +			ret = -ENXIO;
> +			goto err2;
> +		}
> +	}
> +
> +	/* mask all interrupts using priority */
> +	for (k = 0; k < p->number_of_irqs; k++)
> +		intc_irqpin_mask_unmask_prio(p, k, 1);
> +
> +	/* use more severe masking method if requested */
> +	if (p->config.control_parent) {
> +		enable_fn = intc_irqpin_irq_enable_force;
> +		disable_fn = intc_irqpin_irq_disable_force;
> +	} else {
> +		enable_fn = intc_irqpin_irq_enable;
> +		disable_fn = intc_irqpin_irq_disable;
> +	}
> +
> +	irq_chip = &p->irq_chip;
> +	irq_chip->name = name;
> +	irq_chip->irq_mask = disable_fn;
> +	irq_chip->irq_unmask = enable_fn;
> +	irq_chip->irq_enable = enable_fn;
> +	irq_chip->irq_disable = disable_fn;
> +	irq_chip->irq_set_type = intc_irqpin_irq_set_type;
> +	irq_chip->flags	= IRQCHIP_SKIP_SET_WAKE;
> +
> +	p->irq_domain = irq_domain_add_simple(pdev->dev.of_node,
> +					      p->number_of_irqs,
> +					      p->config.irq_base,
> +					      &intc_irqpin_irq_domain_ops, p);
> +	if (!p->irq_domain) {
> +		ret = -ENXIO;
> +		dev_err(&pdev->dev, "cannot initialize irq domain\n");
> +		goto err2;
> +	}
> +
> +	/* request and set priority on interrupts one by one */
> +	for (k = 0; k < p->number_of_irqs; k++) {
> +		if (request_irq(p->irq[k].irq, intc_irqpin_irq_handler,
> +				0, name, &p->irq[k])) {
> +			dev_err(&pdev->dev, "failed to request low IRQ\n");
> +			ret = -ENOENT;
> +			goto err3;
> +		}
> +		intc_irqpin_mask_unmask_prio(p, k, 0);
> +	}
> +
> +	dev_info(&pdev->dev, "driving %d irqs\n", p->number_of_irqs);
> +
> +	/* warn in case of mismatch if irq base is specified */
> +	if (p->config.irq_base) {
> +		k = irq_find_mapping(p->irq_domain, 0);
> +		if (p->config.irq_base != k)
> +			dev_warn(&pdev->dev, "irq base mismatch (%d/%d)\n",
> +				 p->config.irq_base, k);
> +	}
> +	

And here.

> +	return 0;
> +
> +err3:
> +	for (; k >= 0; k--)
> +		free_irq(p->irq[k - 1].irq, &p->irq[k - 1]);
> +
> +	irq_domain_remove(p->irq_domain);
> +err2:
> +	for (k = 0; k < INTC_IRQPIN_REG_NR; k++)
> +		iounmap(p->iomem[k].iomem);
> +err1:
> +	kfree(p);
> +err0:
> +	return ret;
> +}
> +
> +static int intc_irqpin_remove(struct platform_device *pdev)
> +{
> +	struct intc_irqpin_priv *p = platform_get_drvdata(pdev);
> +	int k;
> +
> +	for (k = 0; k < p->number_of_irqs; k++)
> +		free_irq(p->irq[k].irq, &p->irq[k]);
> +
> +	irq_domain_remove(p->irq_domain);
> +
> +	for (k = 0; k < INTC_IRQPIN_REG_NR; k++)
> +		iounmap(p->iomem[k].iomem);
> +
> +	kfree(p);
> +	return 0;
> +}
> +
> +static struct platform_driver intc_irqpin_device_driver = {
> +	.probe		= intc_irqpin_probe,
> +	.remove		= intc_irqpin_remove,
> +	.driver		= {
> +		.name	= "renesas_intc_irqpin",
> +	}
> +};
> +
> +static int __init intc_irqpin_init(void)
> +{
> +	return platform_driver_register(&intc_irqpin_device_driver);
> +}
> +postcore_initcall(intc_irqpin_init);
> +
> +static void __exit intc_irqpin_exit(void)
> +{
> +	platform_driver_unregister(&intc_irqpin_device_driver);
> +}
> +module_exit(intc_irqpin_exit);
> +
> +MODULE_AUTHOR("Magnus Damm");
> +MODULE_DESCRIPTION("Renesas INTC External IRQ Pin Driver");
> +MODULE_LICENSE("GPL v2");
> --- /dev/null
> +++ work/include/linux/platform_data/irq-renesas-intc-irqpin.h	2013-02-18 18:28:24.000000000 +0900
> @@ -0,0 +1,10 @@
> +#ifndef __IRQ_RENESAS_INTC_IRQPIN_H__
> +#define __IRQ_RENESAS_INTC_IRQPIN_H__
> +
> +struct renesas_intc_irqpin_config {
> +	unsigned int sense_bitfield_width;
> +	unsigned int irq_base;
> +	bool control_parent;
> +};
> +
> +#endif /* __IRQ_RENESAS_INTC_IRQPIN_H__ */
> 
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