Re: [PATCH 2/3] irqchip: SigmaStar SSD20xD gpi

[Marc Zyngier <maz@kernel.org>]

On Tue, 14 Sep 2021 11:04:14 +0100,
Daniel Palmer <daniel@0x0f.com> wrote:
> 
> Add support for the SigmaStar GPIO interrupt controller, gpi,
> that is present in SSD201 and SSD202D SoCs.
> 
> This routes interrupts from many interrupts into a single
> interrupt that is connected to the peripheral interrupt
> controller.
> 
> Signed-off-by: Daniel Palmer <daniel@0x0f.com>
> ---
>  MAINTAINERS                       |   1 +
>  drivers/irqchip/Kconfig           |  11 ++
>  drivers/irqchip/Makefile          |   2 +
>  drivers/irqchip/irq-ssd20xd-gpi.c | 211 ++++++++++++++++++++++++++++++
>  4 files changed, 225 insertions(+)
>  create mode 100644 drivers/irqchip/irq-ssd20xd-gpi.c
> 
> diff --git a/MAINTAINERS b/MAINTAINERS
> index 3004c0f735b6..487d5e62c287 100644
> --- a/MAINTAINERS
> +++ b/MAINTAINERS
> @@ -2248,6 +2248,7 @@ F:	arch/arm/boot/dts/mstar-*
>  F:	arch/arm/mach-mstar/
>  F:	drivers/clk/mstar/
>  F:	drivers/gpio/gpio-msc313.c
> +F:	drivers/irqchip/irq-ssd20xd-gpi.c
>  F:	drivers/watchdog/msc313e_wdt.c
>  F:	include/dt-bindings/clock/mstar-*
>  F:	include/dt-bindings/gpio/msc313-gpio.h
> diff --git a/drivers/irqchip/Kconfig b/drivers/irqchip/Kconfig
> index 4d5924e9f766..8786aed7f776 100644
> --- a/drivers/irqchip/Kconfig
> +++ b/drivers/irqchip/Kconfig
> @@ -582,6 +582,17 @@ config MST_IRQ
>  	help
>  	  Support MStar Interrupt Controller.
>  
> +config SSD20XD_GPI
> +	bool "SigmaStar SSD20xD GPIO Interrupt Controller"
> +	depends on ARCH_MSTARV7 || COMPILE_TEST
> +	default ARCH_MSTARV7
> +	select IRQ_DOMAIN
> +	select IRQ_DOMAIN_HIERARCHY
> +	select REGMAP
> +	help
> +	  Support for the SigmaStar GPIO interrupt controller
> +	  found in SSD201, SSD202D and others.
> +
>  config WPCM450_AIC
>  	bool "Nuvoton WPCM450 Advanced Interrupt Controller"
>  	depends on ARCH_WPCM450
> diff --git a/drivers/irqchip/Makefile b/drivers/irqchip/Makefile
> index f88cbf36a9d2..1a6c3dbd67a8 100644
> --- a/drivers/irqchip/Makefile
> +++ b/drivers/irqchip/Makefile
> @@ -116,3 +116,5 @@ obj-$(CONFIG_MACH_REALTEK_RTL)		+= irq-realtek-rtl.o
>  obj-$(CONFIG_WPCM450_AIC)		+= irq-wpcm450-aic.o
>  obj-$(CONFIG_IRQ_IDT3243X)		+= irq-idt3243x.o
>  obj-$(CONFIG_APPLE_AIC)			+= irq-apple-aic.o
> +obj-$(CONFIG_SSD20XD_GPI)		+= irq-ssd20xd-gpi.o
> +
> diff --git a/drivers/irqchip/irq-ssd20xd-gpi.c b/drivers/irqchip/irq-ssd20xd-gpi.c
> new file mode 100644
> index 000000000000..c34f41380717
> --- /dev/null
> +++ b/drivers/irqchip/irq-ssd20xd-gpi.c
> @@ -0,0 +1,211 @@
> +// SPDX-License-Identifier: GPL-2.0
> +/*
> + * Copyright (C) 2021 Daniel Palmer <daniel@thingy.jp>
> + */
> +
> +#include <linux/irq.h>
> +#include <linux/irqchip.h>
> +#include <linux/irqdomain.h>
> +#include <linux/irqchip/chained_irq.h>
> +#include <linux/of.h>
> +#include <linux/of_address.h>
> +#include <linux/of_irq.h>
> +#include <linux/mfd/syscon.h>
> +#include <linux/regmap.h>
> +#include <linux/interrupt.h>
> +
> +#define NUM_IRQ		76
> +#define IRQS_PER_REG	16
> +#define STRIDE		4
> +
> +#define REG_MASK	0x0
> +#define REG_ACK		0x28
> +#define REG_TYPE	0x40
> +#define REG_STATUS	0xc0
> +
> +struct ssd20xd_gpi {
> +	struct regmap *regmap;
> +	struct irq_domain *domain;
> +};
> +
> +#define REG_OFFSET(_hwirq) ((hwirq >> 4) * STRIDE)
> +#define BIT_OFFSET(_hwirq) (1 << (hwirq & 0xf))
> +
> +static void ssd20xd_gpi_mask_irq(struct irq_data *data)
> +{
> +	irq_hw_number_t hwirq = irqd_to_hwirq(data);
> +	struct ssd20xd_gpi *gpi = irq_data_get_irq_chip_data(data);
> +	int offset_reg = REG_OFFSET(hwirq);
> +	int offset_bit = BIT_OFFSET(hwirq);
> +
> +	regmap_update_bits(gpi->regmap, REG_MASK + offset_reg, offset_bit, offset_bit);
> +}
> +
> +static void ssd20xd_gpi_unmask_irq(struct irq_data *data)
> +{
> +	irq_hw_number_t hwirq = irqd_to_hwirq(data);
> +	struct ssd20xd_gpi *gpi = irq_data_get_irq_chip_data(data);
> +	int offset_reg = REG_OFFSET(hwirq);
> +	int offset_bit = BIT_OFFSET(hwirq);
> +
> +	regmap_update_bits(gpi->regmap, REG_MASK + offset_reg, offset_bit, 0);

Is this regmap call atomic? When running this, you are holding a
raw_spinlock already. From what I can see, this is unlikely to work
correctly with the current state of regmap.

> +}
> +
> +static void ssd20xd_gpi_irq_eoi(struct irq_data *data)
> +{
> +	struct ssd20xd_gpi *gpi = irq_data_get_irq_chip_data(data);
> +	irq_hw_number_t hwirq = irqd_to_hwirq(data);
> +	int offset_reg = REG_OFFSET(hwirq);
> +	int offset_bit = BIT_OFFSET(hwirq);
> +
> +	regmap_update_bits_base(gpi->regmap, REG_ACK + offset_reg,
> +			offset_bit, offset_bit, NULL, false, true);
> +}
> +
> +static int ssd20xd_gpi_set_type_irq(struct irq_data *data, unsigned int flow_type)
> +{
> +	irq_hw_number_t hwirq = irqd_to_hwirq(data);
> +	struct ssd20xd_gpi *gpi = irq_data_get_irq_chip_data(data);
> +	int offset_reg = REG_OFFSET(hwirq);
> +	int offset_bit = BIT_OFFSET(hwirq);
> +
> +	switch (flow_type) {
> +	case IRQ_TYPE_EDGE_FALLING:
> +		regmap_update_bits(gpi->regmap, REG_TYPE + offset_reg, offset_bit, offset_bit);
> +		break;
> +	case IRQ_TYPE_EDGE_RISING:
> +		regmap_update_bits(gpi->regmap, REG_TYPE + offset_reg, offset_bit, 0);
> +		break;
> +	default:
> +		return -EINVAL;
> +	}
> +
> +	return 0;
> +}
> +
> +static struct irq_chip ssd20xd_gpi_chip = {
> +	.name		= "GPI",
> +	.irq_mask	= ssd20xd_gpi_mask_irq,
> +	.irq_unmask	= ssd20xd_gpi_unmask_irq,
> +	.irq_eoi	= ssd20xd_gpi_irq_eoi,
> +	.irq_set_type	= ssd20xd_gpi_set_type_irq,
> +};
> +
> +static int ssd20xd_gpi_domain_alloc(struct irq_domain *domain, unsigned int virq,
> +				    unsigned int nr_irqs, void *arg)
> +{
> +	struct ssd20xd_gpi *intc = domain->host_data;
> +	struct irq_fwspec *fwspec = arg;
> +	int i;
> +
> +	for (i = 0; i < nr_irqs; i++)
> +		irq_domain_set_info(domain, virq + i, fwspec->param[0] + i,
> +				&ssd20xd_gpi_chip, intc, handle_fasteoi_irq, NULL, NULL);
> +
> +	return 0;
> +}
> +
> +static void ssd20xd_gpi_domain_free(struct irq_domain *domain, unsigned int virq,
> +				    unsigned int nr_irqs)
> +{
> +	int i;
> +
> +	for (i = 0; i < nr_irqs; i++) {
> +		struct irq_data *d = irq_domain_get_irq_data(domain, virq + i);
> +
> +		irq_set_handler(virq + i, NULL);
> +		irq_domain_reset_irq_data(d);
> +	}
> +}
> +
> +static const struct irq_domain_ops ssd20xd_gpi_domain_ops = {
> +	.alloc = ssd20xd_gpi_domain_alloc,
> +	.free = ssd20xd_gpi_domain_free,
> +};
> +
> +static const struct regmap_config ssd20xd_gpi_regmap_config = {
> +	.reg_bits = 16,
> +	.val_bits = 16,
> +	.reg_stride = 4,
> +};
> +
> +static void ssd20x_gpi_chainedhandler(struct irq_desc *desc)
> +{
> +	struct ssd20xd_gpi *intc = irq_desc_get_handler_data(desc);
> +	struct irq_chip *chip = irq_desc_get_chip(desc);
> +	unsigned int irqbit, hwirq, virq, status;
> +	int i;
> +
> +	chained_irq_enter(chip, desc);
> +
> +	for (i = 0; i < NUM_IRQ / IRQS_PER_REG; i++) {
> +		int offset_reg = STRIDE * i;
> +		int offset_irq = IRQS_PER_REG * i;
> +
> +		regmap_read(intc->regmap, REG_STATUS + offset_reg, &status);

Does this act as an ACK in the HW?

> +
> +		while (status) {
> +			irqbit = __ffs(status);
> +			hwirq = offset_irq + irqbit;
> +			virq = irq_find_mapping(intc->domain, hwirq);
> +			if (virq)
> +				generic_handle_irq(virq);

Please replace this with generic_handle_domain_irq().

> +			status &= ~BIT(irqbit);
> +		}
> +	}
> +
> +	chained_irq_exit(chip, desc);
> +}
> +
> +static int __init ssd20xd_gpi_of_init(struct device_node *node,
> +				      struct device_node *parent)
> +{
> +	struct ssd20xd_gpi *intc;
> +	void __iomem *base;
> +	int irq, ret;
> +
> +	intc = kzalloc(sizeof(*intc), GFP_KERNEL);
> +	if (!intc)
> +		return -ENOMEM;
> +
> +	base = of_iomap(node, 0);
> +	if (!base) {
> +		ret = -ENODEV;
> +		goto out_free;
> +	}
> +
> +	intc->regmap = regmap_init_mmio(NULL, base, &ssd20xd_gpi_regmap_config);
> +	if (IS_ERR(intc->regmap)) {
> +		ret = PTR_ERR(intc->regmap);
> +		goto out_unmap;
> +	}
> +
> +	intc->domain = irq_domain_add_linear(node, NUM_IRQ, &ssd20xd_gpi_domain_ops, intc);
> +	if (!intc->domain) {
> +		ret = -ENOMEM;
> +		goto out_free_regmap;
> +	}
> +
> +	irq = of_irq_get(node, 0);
> +	if (irq <= 0) {
> +		ret = irq;
> +		goto out_free_domain;
> +	}
> +
> +	irq_set_chained_handler_and_data(irq, ssd20x_gpi_chainedhandler,
> +			intc);
> +
> +	return 0;
> +
> +out_free_domain:
> +	irq_domain_remove(intc->domain);
> +out_free_regmap:
> +	regmap_exit(intc->regmap);
> +out_unmap:
> +	iounmap(base);
> +out_free:
> +	kfree(intc);
> +	return ret;
> +}
> +
> +IRQCHIP_DECLARE(ssd20xd_gpi, "sstar,ssd20xd-gpi", ssd20xd_gpi_of_init);

Is there any reason why this isn't a standard platform device? In
general, irqchips that are not part of the root hierarchy shouldn't
need this anymore.

	M.

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