Message-ID: <52EF7D85.5070705@ti.com>
Date:	Mon, 3 Feb 2014 16:59:09 +0530
From:	Sricharan R <r.sricharan@...com>
To:	Thomas Gleixner <tglx@...utronix.de>
CC:	<linux-kernel@...r.kernel.org>, <devicetree@...r.kernel.org>,
	<linux-doc@...r.kernel.org>,
	<linux-arm-kernel@...ts.infradead.org>,
	<linux-omap@...r.kernel.org>, <linus.walleij@...aro.org>,
	<linux@....linux.org.uk>, <tony@...mide.com>, <rnayak@...com>,
	<marc.zyngier@....com>, <grant.likely@...aro.org>,
	<mark.rutland@....com>, <robherring2@...il.com>,
	<tglx@...utronix.de>, <galak@...eaurora.org>,
	<rob.herring@...xeda.com>, <santosh.shilimkar@...com>, <nm@...com>,
	<bcousson@...libre.com>, Kevin Hilman <khilman@...aro.org>,
	Sricharan R <r.sricharan@...com>
Subject: Re: [PATCH V5 2/4] DRIVERS: IRQCHIP: CROSSBAR: Add support for Crossbar
 IP

Hi Thomas,

On Thursday 16 January 2014 03:52 PM, Sricharan R wrote:
> Hi Thomas,
> 
> On Tuesday 03 December 2013 03:57 PM, Sricharan R wrote:
>> Some socs have a large number of interrupts requests to service
>> the needs of its many peripherals and subsystems. All of the
>> interrupt lines from the subsystems are not needed at the same
>> time, so they have to be muxed to the irq-controller appropriately.
>> In such places a interrupt controllers are preceded by an CROSSBAR
>> that provides flexibility in muxing the device requests to the controller
>> inputs.
>>
>> This driver takes care a allocating a free irq and then configuring the
>> crossbar IP as a part of the mpu's irqchip callbacks. crossbar_init should
>> be called right before the irqchip_init, so that it is setup to handle the
>> irqchip callbacks.
>>
>> Cc: Thomas Gleixner <tglx@...utronix.de>
>> Cc: Linus Walleij <linus.walleij@...aro.org>
>> Cc: Santosh Shilimkar <santosh.shilimkar@...com>
>> Cc: Russell King <linux@....linux.org.uk>
>> Cc: Tony Lindgren <tony@...mide.com>
>> Cc: Rajendra Nayak <rnayak@...com>
>> Cc: Marc Zyngier <marc.zyngier@....com>
>> Cc: Grant Likely <grant.likely@...aro.org>
>> Cc: Rob Herring <rob.herring@...xeda.com>
>> Signed-off-by: Sricharan R <r.sricharan@...com>
>> Acked-by: Kumar Gala <galak@...eaurora.org> (for DT binding portion)
>> Acked-by: Santosh Shilimkar <santosh.shilimkar@...com>
>> Acked-by: Linus Walleij <linus.walleij@...aro.org>
>> ---
>>  [v5] Used the function of_property_read_u32_index instead of raw reading
>>       from DT as per comments from Mark Rutland <mark.rutland@....com>
>>
>>  .../devicetree/bindings/arm/omap/crossbar.txt      |   27 +++
>>  drivers/irqchip/Kconfig                            |    8 +
>>  drivers/irqchip/Makefile                           |    1 +
>>  drivers/irqchip/irq-crossbar.c                     |  208 ++++++++++++++++++++
>>  include/linux/irqchip/irq-crossbar.h               |   11 ++
>>  5 files changed, 255 insertions(+)
>>  create mode 100644 Documentation/devicetree/bindings/arm/omap/crossbar.txt
>>  create mode 100644 drivers/irqchip/irq-crossbar.c
>>  create mode 100644 include/linux/irqchip/irq-crossbar.h
>>
>> diff --git a/Documentation/devicetree/bindings/arm/omap/crossbar.txt b/Documentation/devicetree/bindings/arm/omap/crossbar.txt
>> new file mode 100644
>> index 0000000..fb88585
>> --- /dev/null
>> +++ b/Documentation/devicetree/bindings/arm/omap/crossbar.txt
>> @@ -0,0 +1,27 @@
>> +Some socs have a large number of interrupts requests to service
>> +the needs of its many peripherals and subsystems. All of the
>> +interrupt lines from the subsystems are not needed at the same
>> +time, so they have to be muxed to the irq-controller appropriately.
>> +In such places a interrupt controllers are preceded by an CROSSBAR
>> +that provides flexibility in muxing the device requests to the controller
>> +inputs.
>> +
>> +Required properties:
>> +- compatible : Should be "ti,irq-crossbar"
>> +- reg: Base address and the size of the crossbar registers.
>> +- ti,max-irqs: Total number of irqs available at the interrupt controller.
>> +- ti,reg-size: Size of a individual register in bytes. Every individual
>> +	    register is assumed to be of same size. Valid sizes are 1, 2, 4.
>> +- ti,irqs-reserved: List of the reserved irq lines that are not muxed using
>> +		 crossbar. These interrupt lines are reserved in the soc,
>> +		 so crossbar bar driver should not consider them as free
>> +		 lines.
>> +
>> +Examples:
>> +		crossbar_mpu: @4a020000 {
>> +			compatible = "ti,irq-crossbar";
>> +			reg = <0x4a002a48 0x130>;
>> +			ti,max-irqs = <160>;
>> +			ti,reg-size = <2>;
>> +			ti,irqs-reserved = <0 1 2 3 5 6 131 132 139 140>;
>> +		};
>> diff --git a/drivers/irqchip/Kconfig b/drivers/irqchip/Kconfig
>> index 3792a1a..2efcde6 100644
>> --- a/drivers/irqchip/Kconfig
>> +++ b/drivers/irqchip/Kconfig
>> @@ -61,3 +61,11 @@ config VERSATILE_FPGA_IRQ_NR
>>         int
>>         default 4
>>         depends on VERSATILE_FPGA_IRQ
>> +
>> +config IRQ_CROSSBAR
>> +	bool
>> +	help
>> +	  Support for a CROSSBAR ip that preceeds the main interrupt controller.
>> +	  The primary irqchip invokes the crossbar's callback which inturn allocates
>> +	  a free irq and configures the IP. Thus the peripheral interrupts are
>> +	  routed to one of the free irqchip interrupt lines.
>> diff --git a/drivers/irqchip/Makefile b/drivers/irqchip/Makefile
>> index c60b901..2edead9 100644
>> --- a/drivers/irqchip/Makefile
>> +++ b/drivers/irqchip/Makefile
>> @@ -22,3 +22,4 @@ obj-$(CONFIG_RENESAS_IRQC)		+= irq-renesas-irqc.o
>>  obj-$(CONFIG_VERSATILE_FPGA_IRQ)	+= irq-versatile-fpga.o
>>  obj-$(CONFIG_ARCH_VT8500)		+= irq-vt8500.o
>>  obj-$(CONFIG_TB10X_IRQC)		+= irq-tb10x.o
>> +obj-$(CONFIG_IRQ_CROSSBAR)		+= irq-crossbar.o
>> diff --git a/drivers/irqchip/irq-crossbar.c b/drivers/irqchip/irq-crossbar.c
>> new file mode 100644
>> index 0000000..ae605a3
>> --- /dev/null
>> +++ b/drivers/irqchip/irq-crossbar.c
>> @@ -0,0 +1,208 @@
>> +/*
>> + *  drivers/irqchip/irq-crossbar.c
>> + *
>> + *  Copyright (C) 2013 Texas Instruments Incorporated - http://www.ti.com
>> + *  Author: Sricharan R <r.sricharan@...com>
>> + *
>> + * 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.
>> + *
>> + */
>> +#include <linux/err.h>
>> +#include <linux/io.h>
>> +#include <linux/of_address.h>
>> +#include <linux/of_irq.h>
>> +#include <linux/slab.h>
>> +#include <linux/irqchip/arm-gic.h>
>> +
>> +#define IRQ_FREE	-1
>> +#define GIC_IRQ_START	32
>> +
>> +/*
>> + * @int_max: maximum number of supported interrupts
>> + * @irq_map: array of interrupts to crossbar number mapping
>> + * @crossbar_base: crossbar base address
>> + * @register_offsets: offsets for each irq number
>> + */
>> +struct crossbar_device {
>> +	uint int_max;
>> +	uint *irq_map;
>> +	void __iomem *crossbar_base;
>> +	int *register_offsets;
>> +	void (*write) (int, int);
>> +};
>> +
>> +static struct crossbar_device *cb;
>> +
>> +static inline void crossbar_writel(int irq_no, int cb_no)
>> +{
>> +	writel(cb_no, cb->crossbar_base + cb->register_offsets[irq_no]);
>> +}
>> +
>> +static inline void crossbar_writew(int irq_no, int cb_no)
>> +{
>> +	writew(cb_no, cb->crossbar_base + cb->register_offsets[irq_no]);
>> +}
>> +
>> +static inline void crossbar_writeb(int irq_no, int cb_no)
>> +{
>> +	writeb(cb_no, cb->crossbar_base + cb->register_offsets[irq_no]);
>> +}
>> +
>> +static inline int allocate_free_irq(int cb_no)
>> +{
>> +	int i;
>> +
>> +	for (i = 0; i < cb->int_max; i++) {
>> +		if (cb->irq_map[i] == IRQ_FREE) {
>> +			cb->irq_map[i] = cb_no;
>> +			return i;
>> +		}
>> +	}
>> +
>> +	return -ENODEV;
>> +}
>> +
>> +static int crossbar_domain_map(struct irq_domain *d, unsigned int irq,
>> +			       irq_hw_number_t hw)
>> +{
>> +	cb->write(hw - GIC_IRQ_START, cb->irq_map[hw - GIC_IRQ_START]);
>> +	return 0;
>> +}
>> +
>> +static void crossbar_domain_unmap(struct irq_domain *d, unsigned int irq)
>> +{
>> +	irq_hw_number_t hw = irq_get_irq_data(irq)->hwirq;
>> +
>> +	if (hw > GIC_IRQ_START)
>> +		cb->irq_map[hw - GIC_IRQ_START] = IRQ_FREE;
>> +}
>> +
>> +static int crossbar_domain_xlate(struct irq_domain *d,
>> +				 struct device_node *controller,
>> +				 const u32 *intspec, unsigned int intsize,
>> +				 unsigned long *out_hwirq,
>> +				 unsigned int *out_type)
>> +{
>> +	unsigned long ret;
>> +
>> +	ret = allocate_free_irq(intspec[1]);
>> +
>> +	if (IS_ERR_VALUE(ret))
>> +		return ret;
>> +
>> +	*out_hwirq = ret + GIC_IRQ_START;
>> +	return 0;
>> +}
>> +
>> +const struct irq_domain_ops routable_irq_domain_ops = {
>> +	.map = crossbar_domain_map,
>> +	.unmap = crossbar_domain_unmap,
>> +	.xlate = crossbar_domain_xlate
>> +};
>> +
>> +static int __init crossbar_of_init(struct device_node *node)
>> +{
>> +	int i, size, max, reserved = 0, entry;
>> +	const __be32 *irqsr;
>> +
>> +	cb = kzalloc(sizeof(struct cb_device *), GFP_KERNEL);
>> +
>> +	if (!cb)
>> +		return -ENOMEM;
>> +
>> +	cb->crossbar_base = of_iomap(node, 0);
>> +	if (!cb->crossbar_base)
>> +		goto err1;
>> +
>> +	of_property_read_u32(node, "ti,max-irqs", &max);
>> +	cb->irq_map = kzalloc(max * sizeof(int), GFP_KERNEL);
>> +	if (!cb->irq_map)
>> +		goto err2;
>> +
>> +	cb->int_max = max;
>> +
>> +	for (i = 0; i < max; i++)
>> +		cb->irq_map[i] = IRQ_FREE;
>> +
>> +	/* Get and mark reserved irqs */
>> +	irqsr = of_get_property(node, "ti,irqs-reserved", &size);
>> +	if (irqsr) {
>> +		size /= sizeof(__be32);
>> +
>> +		for (i = 0; i < size; i++) {
>> +			of_property_read_u32_index(node,
>> +						   "ti,irqs-reserved",
>> +						   i, &entry);
>> +			if (entry > max) {
>> +				pr_err("Invalid reserved entry\n");
>> +				goto err3;
>> +			}
>> +			cb->irq_map[entry] = 0;
>> +		}
>> +	}
>> +
>> +	cb->register_offsets = kzalloc(max * sizeof(int), GFP_KERNEL);
>> +	if (!cb->register_offsets)
>> +		goto err3;
>> +
>> +	of_property_read_u32(node, "ti,reg-size", &size);
>> +
>> +	switch (size) {
>> +	case 1:
>> +		cb->write = crossbar_writeb;
>> +		break;
>> +	case 2:
>> +		cb->write = crossbar_writew;
>> +		break;
>> +	case 4:
>> +		cb->write = crossbar_writel;
>> +		break;
>> +	default:
>> +		pr_err("Invalid reg-size property\n");
>> +		goto err4;
>> +		break;
>> +	}
>> +
>> +	/*
>> +	 * Register offsets are not linear because of the
>> +	 * reserved irqs. so find and store the offsets once.
>> +	 */
>> +	for (i = 0; i < max; i++) {
>> +		if (!cb->irq_map[i])
>> +			continue;
>> +
>> +		cb->register_offsets[i] = reserved;
>> +		reserved += size;
>> +	}
>> +
>> +	register_routable_domain_ops(&routable_irq_domain_ops);
>> +	return 0;
>> +
>> +err4:
>> +	kfree(cb->register_offsets);
>> +err3:
>> +	kfree(cb->irq_map);
>> +err2:
>> +	iounmap(cb->crossbar_base);
>> +err1:
>> +	kfree(cb);
>> +	return -ENOMEM;
>> +}
>> +
>> +static const struct of_device_id crossbar_match[] __initconst = {
>> +	{ .compatible = "ti,irq-crossbar" },
>> +	{}
>> +};
>> +
>> +int irqcrossbar_init(void)
>> +{
>> +	struct device_node *np;
>> +	np = of_find_matching_node(NULL, crossbar_match);
>> +	if (!np)
>> +		return -ENODEV;
>> +
>> +	crossbar_of_init(np);
>> +	return 0;
>> +}
>> diff --git a/include/linux/irqchip/irq-crossbar.h b/include/linux/irqchip/irq-crossbar.h
>> new file mode 100644
>> index 0000000..e5537b8
>> --- /dev/null
>> +++ b/include/linux/irqchip/irq-crossbar.h
>> @@ -0,0 +1,11 @@
>> +/*
>> + *  drivers/irqchip/irq-crossbar.h
>> + *
>> + *  Copyright (C) 2013 Texas Instruments Incorporated - http://www.ti.com
>> + *
>> + * 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.
>> + *
>> + */
>> +int irqcrossbar_init(void);
> 
> I already have your reviewed-by tag for the first patch in this series.
> 
> Kevin was pointing out that irqchip maintainer tag is needed for this patch as well
> to be merged. We are planning to take this series through arm-soc tree.
> 
> Can i please have your tag for this patch as well ?
> 
  Ping..

Regards,
 Sricharan

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