Subject: Re: [RESEND PATCH v5 2/5] irqchip/irq-pruss-intc: Add a PRUSS irqchip driver for PRUSS interrupts

From: Marc Zyngier <[email-masked]>
Date: Sat, 12 Sep 2020 10:44:45 +0100

On Mon, 31 Aug 2020 16:09:15 +0100,
Grzegorz Jaszczyk <[email-masked]> wrote:
> 
> 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 (for interrupts routed to PRU cores) or via the PRU
> application's device tree node (for interrupt routed to the main CPU).
> In the first case the mappings will be programmed on PRU remoteproc
> driver demand (via irq_create_fwspec_mapping) during the boot of a PRU
> core and cleaned up after the PRU core is stopped.
> 
> Reference counting is used to allow multiple system events to share a
> single channel and to allow multiple channels to share a single host
> event.
> 
> 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: Suman Anna <[email-masked]>
> Signed-off-by: Andrew F. Davis <[email-masked]>
> Signed-off-by: Roger Quadros <[email-masked]>
> Signed-off-by: David Lechner <[email-masked]>
> Signed-off-by: Grzegorz Jaszczyk <[email-masked]>
> ---
> v4->v5:
> - Use more meaningful define and variable names.
> - Drop redundant error messages.
> - Fix error handling in case of irq == 0.
> - Improve @lock description.
> - Add David Lechner copyright and sign-off.
> v3->v4:
> - Introduce new structure for host_irq data and associate it to the
>   chained interrupt handler.
> - Improve pruss_intc_irq_handler: get use of new host_irq data
>   structure; improve while loop to use one register read; convert
>   WARN_ON to WARN_ON_ONCE.
> - Convert irq_linear_revmap into irq_find_mapping.
> - Clarify information about PRU system events type (edge vs level) by
>   introducing proper updates to the driver description.
> - Squash generic part of "irqchip/irq-pruss-intc: Add support for ICSSG
>   INTC on K3 SoCs" patch into this one - it allows to reduce entire
>   patchset diff.
> - Drop reviewed-by due to introduced changes.
> - Extend module authors list.
> - Squash patch #6 of previous patchset "irqchip/irq-pruss-intc: Add
>   event mapping support" into this one and introduce below changes:
>   - Get rid of the two distinct code paths in the xlate function and allow
>     to proceed only with 3 parameters description
>     (system_event/channel/host_irq).
>   - Improve error messages and introduce code simplification.
>   - Add extra logic to xlate function which allows to validate existing
>     interrupt routing violation.
>   - Relax map/unmap validation due to introduced changes in xlate
>     function.
>   - Update commit log description.
> v2->v3:
> - use single irqchip description instead of separately allocating it for
>   each pruss_intc
> - get rid of unused mutex
> - improve error handling
> v1->v2:
> - https://patchwork.kernel.org/patch/11069771/
> ---
>  drivers/irqchip/Kconfig          |  10 +
>  drivers/irqchip/Makefile         |   1 +
>  drivers/irqchip/irq-pruss-intc.c | 590 +++++++++++++++++++++++++++++++++++++++
>  3 files changed, 601 insertions(+)
>  create mode 100644 drivers/irqchip/irq-pruss-intc.c
> 
> diff --git a/drivers/irqchip/Kconfig b/drivers/irqchip/Kconfig
> index bb70b71..a112a76 100644
> --- a/drivers/irqchip/Kconfig
> +++ b/drivers/irqchip/Kconfig
> @@ -493,6 +493,16 @@ 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_AM43XX || 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.
> +
>  config RISCV_INTC
>  	bool "RISC-V Local Interrupt Controller"
>  	depends on RISCV
> diff --git a/drivers/irqchip/Makefile b/drivers/irqchip/Makefile
> index 133f9c4..990a106 100644
> --- a/drivers/irqchip/Makefile
> +++ b/drivers/irqchip/Makefile
> @@ -106,6 +106,7 @@ 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-$(CONFIG_TI_PRUSS_INTC)		+= irq-pruss-intc.o
>  obj-$(CONFIG_LOONGSON_LIOINTC)		+= irq-loongson-liointc.o
>  obj-$(CONFIG_LOONGSON_HTPIC)		+= irq-loongson-htpic.o
>  obj-$(CONFIG_LOONGSON_HTVEC)		+= irq-loongson-htvec.o
> diff --git a/drivers/irqchip/irq-pruss-intc.c b/drivers/irqchip/irq-pruss-intc.c
> new file mode 100644
> index 0000000..461e81e
> --- /dev/null
> +++ b/drivers/irqchip/irq-pruss-intc.c
> @@ -0,0 +1,590 @@
> +// SPDX-License-Identifier: GPL-2.0-only
> +/*
> + * PRU-ICSS INTC IRQChip driver for various TI SoCs
> + *
> + * Copyright (C) 2016-2020 Texas Instruments Incorporated - http://www.ti.com/
> + *	Andrew F. Davis <[email-masked]>
> + *	Suman Anna <[email-masked]>
> + *
> + * Copyright (C) 2019 David Lechner <[email-masked]>
> + */
> +
> +#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 FIRST_PRU_HOST_INT	2
> +
> +/* 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_SRSR(x)	(0x0200 + (x) * 4)
> +#define PRU_INTC_SECR(x)	(0x0280 + (x) * 4)
> +#define PRU_INTC_ESR(x)		(0x0300 + (x) * 4)
> +#define PRU_INTC_ECR(x)		(0x0380 + (x) * 4)
> +#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_SIPR(x)	(0x0d00 + (x) * 4)
> +#define PRU_INTC_SITR(x)	(0x0d80 + (x) * 4)
> +#define PRU_INTC_HINLR(x)	(0x1100 + (x) * 4)
> +#define PRU_INTC_HIER		0x1500
> +
> +/* CMR register bit-field macros */
> +#define CMR_EVT_MAP_MASK	0xf
> +#define CMR_EVT_MAP_BITS	8
> +#define CMR_EVT_PER_REG		4
> +
> +/* HMR register bit-field macros */
> +#define HMR_CH_MAP_MASK		0xf
> +#define HMR_CH_MAP_BITS		8
> +#define HMR_CH_PER_REG		4
> +
> +/* HIPIR register bit-fields */
> +#define INTC_HIPIR_NONE_HINT	0x80000000
> +
> +#define MAX_PRU_SYS_EVENTS 160
> +#define MAX_PRU_CHANNELS 20
> +
> +/**
> + * struct pruss_intc_map_record - keeps track of actual mapping state
> + * @value: The currently mapped value (channel or host)
> + * @ref_count: Keeps track of number of current users of this resource
> + */
> +struct pruss_intc_map_record {
> +	u8 value;
> +	u8 ref_count;
> +};
> +
> +/**
> + * struct pruss_intc_match_data - match data to handle SoC variations
> + * @num_system_events: number of input system events handled by the PRUSS INTC
> + * @num_host_events: number of host events (which is equal to number of
> + *		     channels) supported by the PRUSS INTC
> + */
> +struct pruss_intc_match_data {
> +	u8 num_system_events;
> +	u8 num_host_events;
> +};
> +
> +/**
> + * struct pruss_intc - PRUSS interrupt controller structure
> + * @event_channel: current state of system event to channel mappings
> + * @channel_host: current state of channel to host mappings
> + * @irqs: kernel irq numbers corresponding to PRUSS host interrupts
> + * @base: base virtual address of INTC register space
> + * @domain: irq domain for this interrupt controller
> + * @soc_config: cached PRUSS INTC IP configuration data
> + * @dev: PRUSS INTC device pointer
> + * @lock: mutex to serialize interrupts mapping
> + */
> +struct pruss_intc {
> +	struct pruss_intc_map_record event_channel[MAX_PRU_SYS_EVENTS];
> +	struct pruss_intc_map_record channel_host[MAX_PRU_CHANNELS];
> +	unsigned int irqs[MAX_NUM_HOST_IRQS];
> +	void __iomem *base;
> +	struct irq_domain *domain;
> +	const struct pruss_intc_match_data *soc_config;
> +	struct device *dev;
> +	struct mutex lock; /* PRUSS INTC lock */
> +};
> +
> +/**
> + * struct pruss_host_irq_data - PRUSS host irq data structure
> + * @intc: PRUSS interrupt controller pointer
> + * @host_irq: host irq number
> + */
> +struct pruss_host_irq_data {
> +	struct pruss_intc *intc;
> +	u8 host_irq;
> +};
> +
> +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 void pruss_intc_update_cmr(struct pruss_intc *intc, int evt, s8 ch)
> +{
> +	u32 idx, offset, val;
> +
> +	idx = evt / CMR_EVT_PER_REG;
> +	offset = (evt % CMR_EVT_PER_REG) * CMR_EVT_MAP_BITS;
> +
> +	val = pruss_intc_read_reg(intc, PRU_INTC_CMR(idx));
> +	val &= ~(CMR_EVT_MAP_MASK << offset);
> +	val |= ch << offset;

Why is 'ch' a signed value? Shifting a signed value, specially when
casing it to a larger, unsigned type definitely is in UB territory.
Similar funnies can be said about evt.

And given that the caller does use unsigned types, you really are
asking for trouble. Please fix this.

> +	pruss_intc_write_reg(intc, PRU_INTC_CMR(idx), val);
> +
> +	dev_dbg(intc->dev, "SYSEV%u -> CH%d (CMR%d 0x%08x)\n", evt, ch,
> +		idx, pruss_intc_read_reg(intc, PRU_INTC_CMR(idx)));
> +}
> +
> +static void pruss_intc_update_hmr(struct pruss_intc *intc, int ch, s8 host)
> +{
> +	u32 idx, offset, val;
> +
> +	idx = ch / HMR_CH_PER_REG;
> +	offset = (ch % HMR_CH_PER_REG) * HMR_CH_MAP_BITS;
> +
> +	val = pruss_intc_read_reg(intc, PRU_INTC_HMR(idx));
> +	val &= ~(HMR_CH_MAP_MASK << offset);
> +	val |= host << offset;

Same issues.

> +	pruss_intc_write_reg(intc, PRU_INTC_HMR(idx), val);
> +
> +	dev_dbg(intc->dev, "CH%d -> HOST%d (HMR%d 0x%08x)\n", ch, host, idx,
> +		pruss_intc_read_reg(intc, PRU_INTC_HMR(idx)));
> +}
> +
> +/**
> + * pruss_intc_map() - configure the PRUSS INTC
> + * @intc: PRUSS interrupt controller pointer
> + * @hwirq: the system event number
> + *
> + * Configures the PRUSS INTC with the provided configuration from the one parsed
> + * in the xlate function.
> + */
> +static void pruss_intc_map(struct pruss_intc *intc, unsigned long hwirq)
> +{
> +	struct device *dev = intc->dev;
> +	u8 ch, host, reg_idx;
> +	u32 val;
> +
> +	mutex_lock(&intc->lock);
> +
> +	intc->event_channel[hwirq].ref_count++;
> +
> +	ch = intc->event_channel[hwirq].value;
> +	host = intc->channel_host[ch].value;
> +
> +	pruss_intc_update_cmr(intc, hwirq, ch);
> +
> +	reg_idx = hwirq / 32;
> +	val = BIT(hwirq  % 32);
> +
> +	/* clear and enable system event */
> +	pruss_intc_write_reg(intc, PRU_INTC_ESR(reg_idx), val);
> +	pruss_intc_write_reg(intc, PRU_INTC_SECR(reg_idx), val);
> +
> +	if (++intc->channel_host[ch].ref_count == 1) {
> +		pruss_intc_update_hmr(intc, ch, host);
> +
> +		/* enable host interrupts */
> +		pruss_intc_write_reg(intc, PRU_INTC_HIEISR, host);
> +	}
> +
> +	dev_dbg(dev, "mapped system_event = %lu channel = %d host = %d",
> +		hwirq, ch, host);
> +
> +	/* global interrupt enable */
> +	pruss_intc_write_reg(intc, PRU_INTC_GER, 1);

Is it safe to always write this register every time something gets
mapped?

> +
> +	mutex_unlock(&intc->lock);
> +}
> +
> +/**
> + * pruss_intc_unmap() - unconfigure the PRUSS INTC
> + * @intc: PRUSS interrupt controller pointer
> + * @hwirq: the system event number
> + *
> + * Undo whatever was done in pruss_intc_map() for a PRU core.
> + * Mappings are reference counted, so resources are only disabled when there
> + * are no longer any users.
> + */
> +static void pruss_intc_unmap(struct pruss_intc *intc, unsigned long hwirq)
> +{
> +	u8 ch, host, reg_idx;
> +	u32 val;
> +
> +	mutex_lock(&intc->lock);
> +
> +	ch = intc->event_channel[hwirq].value;
> +	host = intc->channel_host[ch].value;
> +
> +	if (--intc->channel_host[ch].ref_count == 0) {
> +		/* disable host interrupts */
> +		pruss_intc_write_reg(intc, PRU_INTC_HIDISR, host);
> +
> +		/* clear the map using reset value 0 */
> +		pruss_intc_update_hmr(intc, ch, 0);
> +	}
> +
> +	intc->event_channel[hwirq].ref_count--;
> +	reg_idx = hwirq / 32;
> +	val = BIT(hwirq  % 32);
> +
> +	/* disable system events */
> +	pruss_intc_write_reg(intc, PRU_INTC_ECR(reg_idx), val);
> +	/* clear any pending status */
> +	pruss_intc_write_reg(intc, PRU_INTC_SECR(reg_idx), val);
> +
> +	/* clear the map using reset value 0 */
> +	pruss_intc_update_cmr(intc, hwirq, 0);
> +
> +	dev_dbg(intc->dev, "unmapped system_event = %lu channel = %d host = %d\n",
> +		hwirq, ch, host);
> +
> +	mutex_unlock(&intc->lock);

Conversely, you never write 0 to PRU_INTC_GER. So why is the enable in
the map function and not simply set at init time, once and for all?

> +}
> +
> +static void pruss_intc_init(struct pruss_intc *intc)
> +{
> +	const struct pruss_intc_match_data *soc_config = intc->soc_config;
> +	int i;
> +	int num_chnl_map_regs = DIV_ROUND_UP(soc_config->num_system_events,
> +					     CMR_EVT_PER_REG);
> +	int num_host_intr_regs = DIV_ROUND_UP(soc_config->num_host_events,
> +					      HMR_CH_PER_REG);
> +	int num_event_type_regs =
> +			DIV_ROUND_UP(soc_config->num_system_events, 32);

Please keep assignments on a single line.

> +
> +	/*
> +	 * configure polarity (SIPR register) to active high and
> +	 * type (SITR register) to level interrupt for all system events
> +	 */
> +	for (i = 0; i < num_event_type_regs; i++) {
> +		pruss_intc_write_reg(intc, PRU_INTC_SIPR(i), 0xffffffff);
> +		pruss_intc_write_reg(intc, PRU_INTC_SITR(i), 0);
> +	}
> +
> +	/* clear all interrupt channel map registers, 4 events per register */
> +	for (i = 0; i < num_chnl_map_regs; i++)
> +		pruss_intc_write_reg(intc, PRU_INTC_CMR(i), 0);
> +
> +	/* clear all host interrupt map registers, 4 channels per register */
> +	for (i = 0; i < num_host_intr_regs; 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_write_reg(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_write_reg(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_write_reg(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 struct irq_chip pruss_irqchip = {
> +	.name = "pruss-intc",
> +	.irq_ack = pruss_intc_irq_ack,
> +	.irq_mask = pruss_intc_irq_mask,
> +	.irq_unmask = pruss_intc_irq_unmask,
> +	.irq_request_resources = pruss_intc_irq_reqres,
> +	.irq_release_resources = pruss_intc_irq_relres,

nit: align the = signs vertically so that the structure is readable.

> +};
> +
> +static int pruss_intc_validate_mapping(struct pruss_intc *intc, int event,
> +				       int channel, int host)
> +{
> +	struct device *dev = intc->dev;
> +	int ret = 0;
> +
> +	mutex_lock(&intc->lock);
> +
> +	/* check if sysevent already assigned */
> +	if (intc->event_channel[event].ref_count > 0 &&
> +	    intc->event_channel[event].value != channel) {
> +		dev_err(dev, "event %d (req. ch %d) already assigned to channel %d\n",
> +			event, channel, intc->event_channel[event].value);
> +		ret = -EBUSY;
> +		goto unlock;
> +	}
> +
> +	/* check if channel already assigned */
> +	if (intc->channel_host[channel].ref_count > 0 &&
> +	    intc->channel_host[channel].value != host) {
> +		dev_err(dev, "channel %d (req. host %d) already assigned to host %d\n",
> +			channel, host, intc->channel_host[channel].value);
> +		ret = -EBUSY;
> +		goto unlock;
> +	}
> +
> +	intc->event_channel[event].value = channel;
> +	intc->channel_host[channel].value = host;
> +
> +unlock:
> +	mutex_unlock(&intc->lock);
> +	return ret;
> +}
> +
> +static int
> +pruss_intc_irq_domain_xlate(struct irq_domain *d, struct device_node *node,
> +			    const u32 *intspec, unsigned int intsize,
> +			    unsigned long *out_hwirq, unsigned int *out_type)
> +{
> +	struct pruss_intc *intc = d->host_data;
> +	struct device *dev = intc->dev;
> +	int ret, sys_event, channel, host;
> +
> +	if (intsize < 3)
> +		return -EINVAL;
> +
> +	sys_event = intspec[0];
> +	if (sys_event < 0 || sys_event >= intc->soc_config->num_system_events) {
> +		dev_err(dev, "%d is not valid event number\n", sys_event);
> +		return -EINVAL;
> +	}
> +
> +	channel = intspec[1];
> +	if (channel < 0 || channel >= intc->soc_config->num_host_events) {
> +		dev_err(dev, "%d is not valid channel number", channel);
> +		return -EINVAL;
> +	}
> +
> +	host = intspec[2];
> +	if (host < 0 || host >= intc->soc_config->num_host_events) {
> +		dev_err(dev, "%d is not valid host irq number\n", host);
> +		return -EINVAL;
> +	}
> +
> +	/* check if requested sys_event was already mapped, if so validate it */
> +	ret = pruss_intc_validate_mapping(intc, sys_event, channel, host);
> +	if (ret)
> +		return ret;
> +
> +	*out_hwirq = sys_event;
> +	*out_type = IRQ_TYPE_NONE;

No. You configure all your interrupts as level interrupts, please let
the kernel know what you are doing.

> +
> +	return 0;
> +}
> +
> +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;
> +
> +	pruss_intc_map(intc, hw);
> +
> +	irq_set_chip_data(virq, intc);
> +	irq_set_chip_and_handler(virq, &pruss_irqchip, handle_level_irq);
> +
> +	return 0;
> +}
> +
> +static void pruss_intc_irq_domain_unmap(struct irq_domain *d, unsigned int virq)
> +{
> +	struct pruss_intc *intc = d->host_data;
> +	unsigned long hwirq = irqd_to_hwirq(irq_get_irq_data(virq));
> +
> +	irq_set_chip_and_handler(virq, NULL, NULL);
> +	irq_set_chip_data(virq, NULL);
> +	pruss_intc_unmap(intc, hwirq);
> +}
> +
> +static const struct irq_domain_ops pruss_intc_irq_domain_ops = {
> +	.xlate	= pruss_intc_irq_domain_xlate,
> +	.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_host_irq_data *host_irq_data = irq_get_handler_data(irq);
> +	struct pruss_intc *intc = host_irq_data->intc;
> +	u32 hipir;
> +	unsigned int virq;
> +	int hwirq;

Move these 3 variables to the inner loop so that it becomes a bit more
readable.

> +	u8 host_irq = host_irq_data->host_irq + FIRST_PRU_HOST_INT;
> +
> +	chained_irq_enter(chip, desc);
> +
> +	while (true) {
> +		/* get highest priority pending PRUSS system event */
> +		hipir = pruss_intc_read_reg(intc, PRU_INTC_HIPIR(host_irq));
> +		if (hipir & INTC_HIPIR_NONE_HINT)
> +			break;
> +
> +		hwirq = hipir & GENMASK(9, 0);
> +		virq = irq_find_mapping(intc->domain, hwirq);
> +
> +		/*
> +		 * NOTE: manually ACK any system events that do not have a
> +		 * handler mapped yet
> +		 */
> +		if (WARN_ON_ONCE(!virq))
> +			pruss_intc_write_reg(intc, PRU_INTC_SICR, hwirq);
> +		else
> +			generic_handle_irq(virq);
> +	}
> +
> +	chained_irq_exit(chip, desc);
> +}
> +
> +static int pruss_intc_probe(struct platform_device *pdev)
> +{
> +	static const char * const irq_names[MAX_NUM_HOST_IRQS] = {
> +		"host_intr0", "host_intr1", "host_intr2", "host_intr3",
> +		"host_intr4", "host_intr5", "host_intr6", "host_intr7", };

Move the static data out of the function. The private scope doesn't
bring anything.

> +	const struct pruss_intc_match_data *data;
> +	struct device *dev = &pdev->dev;
> +	struct pruss_intc *intc;
> +	struct pruss_host_irq_data *host_data[MAX_NUM_HOST_IRQS] = { NULL };
> +	int i, irq, ret;
> +	u8 max_system_events;
> +
> +	data = of_device_get_match_data(dev);
> +	if (!data)
> +		return -ENODEV;
> +
> +	max_system_events = data->num_system_events;
> +
> +	intc = devm_kzalloc(dev, sizeof(*intc), GFP_KERNEL);
> +	if (!intc)
> +		return -ENOMEM;
> +
> +	intc->soc_config = data;
> +	intc->dev = dev;
> +	platform_set_drvdata(pdev, intc);
> +
> +	intc->base = devm_platform_ioremap_resource(pdev, 0);
> +	if (IS_ERR(intc->base))
> +		return PTR_ERR(intc->base);
> +
> +	pruss_intc_init(intc);
> +
> +	mutex_init(&intc->lock);
> +
> +	intc->domain = irq_domain_add_linear(dev->of_node, max_system_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) {
> +			ret = (irq == 0) ? -EINVAL : irq;
> +			goto fail_irq;
> +		}
> +
> +		intc->irqs[i] = irq;
> +
> +		host_data[i] = devm_kzalloc(dev, sizeof(*host_data[0]),
> +					    GFP_KERNEL);

Why is host_data an array? It really doesn't need to.

	M.

-- 
Without deviation from the norm, progress is not possible.

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