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Subject: Re: [PATCH v2 2/6] irqchip/irq-pruss-intc: Add a PRUSS irqchip driver
 for PRUSS interrupts
To:     Suman Anna <s-anna@ti.com>, Thomas Gleixner <tglx@linutronix.de>,
        Jason Cooper <jason@lakedaemon.net>
Cc:     Rob Herring <robh+dt@kernel.org>,
        David Lechner <david@lechnology.com>,
        Tony Lindgren <tony@atomide.com>,
        "Andrew F. Davis" <afd@ti.com>, Roger Quadros <rogerq@ti.com>,
        Lokesh Vutla <lokeshvutla@ti.com>,
        Grygorii Strashko <grygorii.strashko@ti.com>,
        Sekhar Nori <nsekhar@ti.com>,
        Murali Karicheri <m-karicheri2@ti.com>,
        devicetree@vger.kernel.org, linux-omap@vger.kernel.org,
        linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org
References: <20190731224149.11153-1-s-anna@ti.com>
 <20190731224149.11153-3-s-anna@ti.com>
From:   Marc Zyngier <maz@kernel.org>
Organization: Approximate
Message-ID: <d0d539c2-4247-d74e-3bb2-ddb98e0bafb5@kernel.org>
Date:   Thu, 1 Aug 2019 10:42:55 +0100
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On 31/07/2019 23:41, Suman Anna wrote:
> From: "Andrew F. Davis" <afd@ti.com>
> 
> The Programmable Real-Time Unit Subsystem (PRUSS) contains a local
> interrupt controller (INTC) that can handle various system input events
> and post interrupts back to the device-level initiators. The INTC can
> support upto 64 input events with individual control configuration and
> hardware prioritization. These events are mapped onto 10 output interrupt
> lines through two levels of many-to-one mapping support. Different
> interrupt lines are routed to the individual PRU cores or to the host
> CPU, or to other devices on the SoC. Some of these events are sourced
> from peripherals or other sub-modules within that PRUSS, while a few
> others are sourced from SoC-level peripherals/devices.
> 
> The PRUSS INTC platform driver manages this PRUSS interrupt controller
> and implements an irqchip driver to provide a Linux standard way for
> the PRU client users to enable/disable/ack/re-trigger a PRUSS system
> event. The system events to interrupt channels and output interrupts
> relies on the mapping configuration provided either through the PRU
> firmware blob or via the PRU application's device tree node. The
> mappings will be programmed during the boot/shutdown of a PRU core.
> 
> The PRUSS INTC module is reference counted during the interrupt
> setup phase through the irqchip's irq_request_resources() and
> irq_release_resources() ops. This restricts the module from being
> removed as long as there are active interrupt users.
> 
> The driver currently supports and can be built for OMAP architecture
> based AM335x, AM437x and AM57xx SoCs; Keystone2 architecture based
> 66AK2G SoCs and Davinci architecture based OMAP-L13x/AM18x/DA850 SoCs.
> All of these SoCs support 64 system events, 10 interrupt channels and
> 10 output interrupt lines per PRUSS INTC with a few SoC integration
> differences.
> 
> NOTE:
> Each PRU-ICSS's INTC on AM57xx SoCs is preceded by a Crossbar that
> enables multiple external events to be routed to a specific number
> of input interrupt events. Any non-default external interrupt event
> directed towards PRUSS needs this crossbar to be setup properly.
> 
> Signed-off-by: Andrew F. Davis <afd@ti.com>
> Signed-off-by: Suman Anna <s-anna@ti.com>
> Signed-off-by: Roger Quadros <rogerq@ti.com>
> ---
> v2: 
>  - Addressed all of David Lechner's comments
>  - Dropped irq_retrigger callback
>  - Updated interrupt names from "hostX" to "host_intrX"
>  - Moved host_mask variable to patch 4
> v1: https://patchwork.kernel.org/patch/11034545/
> v0: https://patchwork.kernel.org/patch/10795761/
> 
>  drivers/irqchip/Kconfig          |  10 +
>  drivers/irqchip/Makefile         |   1 +
>  drivers/irqchip/irq-pruss-intc.c | 338 +++++++++++++++++++++++++++++++
>  3 files changed, 349 insertions(+)
>  create mode 100644 drivers/irqchip/irq-pruss-intc.c
> 
> diff --git a/drivers/irqchip/Kconfig b/drivers/irqchip/Kconfig
> index 80e10f4e213a..dc6b5aa77a5d 100644
> --- a/drivers/irqchip/Kconfig
> +++ b/drivers/irqchip/Kconfig
> @@ -471,6 +471,16 @@ config TI_SCI_INTA_IRQCHIP
>  	  If you wish to use interrupt aggregator irq resources managed by the
>  	  TI System Controller, say Y here. Otherwise, say N.
>  
> +config TI_PRUSS_INTC
> +	tristate "TI PRU-ICSS Interrupt Controller"
> +	depends on ARCH_DAVINCI || SOC_AM33XX || SOC_AM437X || SOC_DRA7XX || ARCH_KEYSTONE
> +	select IRQ_DOMAIN
> +	help
> +	   This enables support for the PRU-ICSS Local Interrupt Controller
> +	   present within a PRU-ICSS subsystem present on various TI SoCs.
> +	   The PRUSS INTC enables various interrupts to be routed to multiple
> +	   different processors within the SoC.
> +
>  endmenu
>  
>  config SIFIVE_PLIC
> diff --git a/drivers/irqchip/Makefile b/drivers/irqchip/Makefile
> index 8d0fcec6ab23..a02e652ca805 100644
> --- a/drivers/irqchip/Makefile
> +++ b/drivers/irqchip/Makefile
> @@ -102,3 +102,4 @@ obj-$(CONFIG_MADERA_IRQ)		+= irq-madera.o
>  obj-$(CONFIG_LS1X_IRQ)			+= irq-ls1x.o
>  obj-$(CONFIG_TI_SCI_INTR_IRQCHIP)	+= irq-ti-sci-intr.o
>  obj-$(CONFIG_TI_SCI_INTA_IRQCHIP)	+= irq-ti-sci-inta.o
> +obj-$(CONFIG_TI_PRUSS_INTC)		+= irq-pruss-intc.o
> diff --git a/drivers/irqchip/irq-pruss-intc.c b/drivers/irqchip/irq-pruss-intc.c
> new file mode 100644
> index 000000000000..4a9456544fd0
> --- /dev/null
> +++ b/drivers/irqchip/irq-pruss-intc.c
> @@ -0,0 +1,338 @@
> +// SPDX-License-Identifier: GPL-2.0
> +/*
> + * PRU-ICSS INTC IRQChip driver for various TI SoCs
> + *
> + * Copyright (C) 2016-2019 Texas Instruments Incorporated - http://www.ti.com/
> + *	Andrew F. Davis <afd@ti.com>
> + *	Suman Anna <s-anna@ti.com>
> + */
> +
> +#include <linux/irq.h>
> +#include <linux/irqchip/chained_irq.h>
> +#include <linux/irqdomain.h>
> +#include <linux/module.h>
> +#include <linux/of_device.h>
> +#include <linux/platform_device.h>
> +
> +/*
> + * Number of host interrupts reaching the main MPU sub-system. Note that this
> + * is not the same as the total number of host interrupts supported by the PRUSS
> + * INTC instance
> + */
> +#define MAX_NUM_HOST_IRQS	8
> +
> +/* minimum starting host interrupt number for MPU */
> +#define MIN_PRU_HOST_INT	2
> +
> +/* maximum number of system events */
> +#define MAX_PRU_SYS_EVENTS	64
> +
> +/* PRU_ICSS_INTC registers */
> +#define PRU_INTC_REVID		0x0000
> +#define PRU_INTC_CR		0x0004
> +#define PRU_INTC_GER		0x0010
> +#define PRU_INTC_GNLR		0x001c
> +#define PRU_INTC_SISR		0x0020
> +#define PRU_INTC_SICR		0x0024
> +#define PRU_INTC_EISR		0x0028
> +#define PRU_INTC_EICR		0x002c
> +#define PRU_INTC_HIEISR		0x0034
> +#define PRU_INTC_HIDISR		0x0038
> +#define PRU_INTC_GPIR		0x0080
> +#define PRU_INTC_SRSR0		0x0200
> +#define PRU_INTC_SRSR1		0x0204
> +#define PRU_INTC_SECR0		0x0280
> +#define PRU_INTC_SECR1		0x0284
> +#define PRU_INTC_ESR0		0x0300
> +#define PRU_INTC_ESR1		0x0304
> +#define PRU_INTC_ECR0		0x0380
> +#define PRU_INTC_ECR1		0x0384
> +#define PRU_INTC_CMR(x)		(0x0400 + (x) * 4)
> +#define PRU_INTC_HMR(x)		(0x0800 + (x) * 4)
> +#define PRU_INTC_HIPIR(x)	(0x0900 + (x) * 4)
> +#define PRU_INTC_SIPR0		0x0d00
> +#define PRU_INTC_SIPR1		0x0d04
> +#define PRU_INTC_SITR0		0x0d80
> +#define PRU_INTC_SITR1		0x0d84
> +#define PRU_INTC_HINLR(x)	(0x1100 + (x) * 4)
> +#define PRU_INTC_HIER		0x1500
> +
> +/* HIPIR register bit-fields */
> +#define INTC_HIPIR_NONE_HINT	0x80000000
> +
> +/**
> + * struct pruss_intc - PRUSS interrupt controller structure
> + * @irqs: kernel irq numbers corresponding to PRUSS host interrupts
> + * @base: base virtual address of INTC register space
> + * @irqchip: irq chip for this interrupt controller
> + * @domain: irq domain for this interrupt controller
> + * @lock: mutex to serialize access to INTC
> + */
> +struct pruss_intc {
> +	unsigned int irqs[MAX_NUM_HOST_IRQS];
> +	void __iomem *base;
> +	struct irq_chip *irqchip;
> +	struct irq_domain *domain;
> +	struct mutex lock; /* PRUSS INTC lock */

Nothing seem to use that lock in this patch (other than to initialize it).

> +};
> +
> +static inline u32 pruss_intc_read_reg(struct pruss_intc *intc, unsigned int reg)
> +{
> +	return readl_relaxed(intc->base + reg);
> +}
> +
> +static inline void pruss_intc_write_reg(struct pruss_intc *intc,
> +					unsigned int reg, u32 val)
> +{
> +	writel_relaxed(val, intc->base + reg);
> +}
> +
> +static int pruss_intc_check_write(struct pruss_intc *intc, unsigned int reg,
> +				  unsigned int sysevent)
> +{
> +	if (!intc)
> +		return -EINVAL;
> +
> +	if (sysevent >= MAX_PRU_SYS_EVENTS)
> +		return -EINVAL;

How can any of these happen?  That'd be a bug in the driver surely.
Also, nothing ever checks the return value.

> +
> +	pruss_intc_write_reg(intc, reg, sysevent);
> +
> +	return 0;
> +}
> +
> +static void pruss_intc_init(struct pruss_intc *intc)
> +{
> +	int i;
> +
> +	/* configure polarity to active high for all system interrupts */
> +	pruss_intc_write_reg(intc, PRU_INTC_SIPR0, 0xffffffff);
> +	pruss_intc_write_reg(intc, PRU_INTC_SIPR1, 0xffffffff);
> +
> +	/* configure type to pulse interrupt for all system interrupts */
> +	pruss_intc_write_reg(intc, PRU_INTC_SITR0, 0);
> +	pruss_intc_write_reg(intc, PRU_INTC_SITR1, 0);
> +
> +	/* clear all 16 interrupt channel map registers */
> +	for (i = 0; i < 16; i++)
> +		pruss_intc_write_reg(intc, PRU_INTC_CMR(i), 0);
> +
> +	/* clear all 3 host interrupt map registers */
> +	for (i = 0; i < 3; i++)
> +		pruss_intc_write_reg(intc, PRU_INTC_HMR(i), 0);
> +}
> +
> +static void pruss_intc_irq_ack(struct irq_data *data)
> +{
> +	struct pruss_intc *intc = irq_data_get_irq_chip_data(data);
> +	unsigned int hwirq = data->hwirq;
> +
> +	pruss_intc_check_write(intc, PRU_INTC_SICR, hwirq);
> +}
> +
> +static void pruss_intc_irq_mask(struct irq_data *data)
> +{
> +	struct pruss_intc *intc = irq_data_get_irq_chip_data(data);
> +	unsigned int hwirq = data->hwirq;
> +
> +	pruss_intc_check_write(intc, PRU_INTC_EICR, hwirq);
> +}
> +
> +static void pruss_intc_irq_unmask(struct irq_data *data)
> +{
> +	struct pruss_intc *intc = irq_data_get_irq_chip_data(data);
> +	unsigned int hwirq = data->hwirq;
> +
> +	pruss_intc_check_write(intc, PRU_INTC_EISR, hwirq);
> +}
> +
> +static int pruss_intc_irq_reqres(struct irq_data *data)
> +{
> +	if (!try_module_get(THIS_MODULE))
> +		return -ENODEV;
> +
> +	return 0;
> +}
> +
> +static void pruss_intc_irq_relres(struct irq_data *data)
> +{
> +	module_put(THIS_MODULE);
> +}
> +
> +static int pruss_intc_irq_domain_map(struct irq_domain *d, unsigned int virq,
> +				     irq_hw_number_t hw)
> +{
> +	struct pruss_intc *intc = d->host_data;
> +
> +	irq_set_chip_data(virq, intc);
> +	irq_set_chip_and_handler(virq, intc->irqchip, handle_level_irq);
> +
> +	return 0;
> +}
> +
> +static void pruss_intc_irq_domain_unmap(struct irq_domain *d, unsigned int virq)
> +{
> +	irq_set_chip_and_handler(virq, NULL, NULL);
> +	irq_set_chip_data(virq, NULL);
> +}
> +
> +static const struct irq_domain_ops pruss_intc_irq_domain_ops = {
> +	.xlate	= irq_domain_xlate_onecell,
> +	.map	= pruss_intc_irq_domain_map,
> +	.unmap	= pruss_intc_irq_domain_unmap,
> +};
> +
> +static void pruss_intc_irq_handler(struct irq_desc *desc)
> +{
> +	unsigned int irq = irq_desc_get_irq(desc);
> +	struct irq_chip *chip = irq_desc_get_chip(desc);
> +	struct pruss_intc *intc = irq_get_handler_data(irq);
> +	u32 hipir;
> +	unsigned int virq;
> +	int i, hwirq;
> +
> +	chained_irq_enter(chip, desc);
> +
> +	/* find our host irq number */
> +	for (i = 0; i < MAX_NUM_HOST_IRQS; i++)
> +		if (intc->irqs[i] == irq)
> +			break;
> +	if (i == MAX_NUM_HOST_IRQS)
> +		goto err;
> +
> +	i += MIN_PRU_HOST_INT;
> +
> +	/* get highest priority pending PRUSS system event */
> +	hipir = pruss_intc_read_reg(intc, PRU_INTC_HIPIR(i));
> +	while (!(hipir & INTC_HIPIR_NONE_HINT)) {
> +		hwirq = hipir & GENMASK(9, 0);
> +		virq = irq_linear_revmap(intc->domain, hwirq);
> +
> +		/*
> +		 * NOTE: manually ACK any system events that do not have a
> +		 * handler mapped yet
> +		 */
> +		if (unlikely(!virq))
> +			pruss_intc_check_write(intc, PRU_INTC_SICR, hwirq);

How were they configured the first place?

> +		else
> +			generic_handle_irq(virq);
> +
> +		/* get next system event */
> +		hipir = pruss_intc_read_reg(intc, PRU_INTC_HIPIR(i));
> +	}
> +err:
> +	chained_irq_exit(chip, desc);
> +}
> +
> +static int pruss_intc_probe(struct platform_device *pdev)
> +{
> +	static const char * const irq_names[] = {

Should this be sized with MAX_NUM_HOST_IRQS, given that this is how you
parse it?

> +		"host_intr0", "host_intr1", "host_intr2", "host_intr3",
> +		"host_intr4", "host_intr5", "host_intr6", "host_intr7", };
> +	struct device *dev = &pdev->dev;
> +	struct pruss_intc *intc;
> +	struct resource *res;
> +	struct irq_chip *irqchip;
> +	int i, irq;
> +
> +	intc = devm_kzalloc(dev, sizeof(*intc), GFP_KERNEL);
> +	if (!intc)
> +		return -ENOMEM;
> +	platform_set_drvdata(pdev, intc);
> +
> +	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
> +	intc->base = devm_ioremap_resource(dev, res);
> +	if (IS_ERR(intc->base)) {
> +		dev_err(dev, "failed to parse and map intc memory resource\n");
> +		return PTR_ERR(intc->base);
> +	}
> +
> +	dev_dbg(dev, "intc memory: pa %pa size 0x%zx va %pK\n", &res->start,
> +		(size_t)resource_size(res), intc->base);
> +
> +	mutex_init(&intc->lock);
> +
> +	pruss_intc_init(intc);
> +
> +	irqchip = devm_kzalloc(dev, sizeof(*irqchip), GFP_KERNEL);
> +	if (!irqchip)
> +		return -ENOMEM;
> +
> +	irqchip->irq_ack = pruss_intc_irq_ack;
> +	irqchip->irq_mask = pruss_intc_irq_mask;
> +	irqchip->irq_unmask = pruss_intc_irq_unmask;
> +	irqchip->irq_request_resources = pruss_intc_irq_reqres;
> +	irqchip->irq_release_resources = pruss_intc_irq_relres;
> +	irqchip->name = dev_name(dev);
> +	intc->irqchip = irqchip;

Given that each and every pruss_intc ends up with a pointer to its own
irqchip, why is it a separate allocation instead of directly embedding
the structure?

Alternatively, have a single 'static const struct irq_chip' and lose the
slightly pointless dev_name as the irqchip name.

> +
> +	/* always 64 events */
> +	intc->domain = irq_domain_add_linear(dev->of_node, MAX_PRU_SYS_EVENTS,
> +					     &pruss_intc_irq_domain_ops, intc);
> +	if (!intc->domain)
> +		return -ENOMEM;
> +
> +	for (i = 0; i < MAX_NUM_HOST_IRQS; i++) {
> +		irq = platform_get_irq_byname(pdev, irq_names[i]);
> +		if (irq < 0) {

irq == 0 is also an error.

> +			dev_err(dev, "platform_get_irq_byname failed for %s : %d\n",
> +				irq_names[i], irq);
> +			goto fail_irq;
> +		}
> +
> +		intc->irqs[i] = irq;
> +		irq_set_handler_data(irq, intc);
> +		irq_set_chained_handler(irq, pruss_intc_irq_handler);
> +	}
> +
> +	return 0;
> +
> +fail_irq:
> +	while (--i >= 0) {
> +		if (intc->irqs[i])

This 'if' seems supperfluous.

> +			irq_set_chained_handler_and_data(intc->irqs[i], NULL,
> +							 NULL);
> +	}
> +	irq_domain_remove(intc->domain);
> +	return irq;
> +}
> +
> +static int pruss_intc_remove(struct platform_device *pdev)
> +{
> +	struct pruss_intc *intc = platform_get_drvdata(pdev);
> +	unsigned int hwirq;
> +	int i;
> +
> +	for (i = 0; i < MAX_NUM_HOST_IRQS; i++) {
> +		if (intc->irqs[i])

Same here.

> +			irq_set_chained_handler_and_data(intc->irqs[i], NULL,
> +							 NULL);
> +	}
> +
> +	for (hwirq = 0; hwirq < MAX_PRU_SYS_EVENTS; hwirq++)
> +		irq_dispose_mapping(irq_find_mapping(intc->domain, hwirq));
> +	irq_domain_remove(intc->domain);
> +
> +	return 0;
> +}
> +
> +static const struct of_device_id pruss_intc_of_match[] = {
> +	{ .compatible = "ti,pruss-intc", },
> +	{ /* sentinel */ },
> +};
> +MODULE_DEVICE_TABLE(of, pruss_intc_of_match);
> +
> +static struct platform_driver pruss_intc_driver = {
> +	.driver = {
> +		.name = "pruss-intc",
> +		.of_match_table = pruss_intc_of_match,
> +	},
> +	.probe  = pruss_intc_probe,
> +	.remove = pruss_intc_remove,
> +};
> +module_platform_driver(pruss_intc_driver);
> +
> +MODULE_AUTHOR("Andrew F. Davis <afd@ti.com>");
> +MODULE_AUTHOR("Suman Anna <s-anna@ti.com>");
> +MODULE_DESCRIPTION("TI PRU-ICSS INTC Driver");
> +MODULE_LICENSE("GPL v2");
> 

Thanks,
	
	M.
-- 
Jazz is not dead, it just smells funny...