Re: [PATCH 2/4] irqchip: Add Aspeed SCU interrupt controller

Marc Zyngier
2019-09-24T16:47:17Z

Eddie,

On 24/09/2019 17:14, Eddie James wrote:
> The Aspeed SOCs provide some interrupts through the System Control
> Unit registers. Add an interrupt controller that provides these
> interrupts to the system.
>
> Signed-off-by: Eddie James <eajames@linux.ibm.com>
> ---
> MAINTAINERS | 1 +
> drivers/irqchip/Makefile | 2 +-
> drivers/irqchip/irq-aspeed-scu-ic.c | 199 ++++++++++++++++++++++++++++++++++++
> 3 files changed, 201 insertions(+), 1 deletion(-)
> create mode 100644 drivers/irqchip/irq-aspeed-scu-ic.c
>
> diff --git a/MAINTAINERS b/MAINTAINERS
> index 4a1687b..f3f6c3d 100644
> --- a/MAINTAINERS
> +++ b/MAINTAINERS
> @@ -2655,6 +2655,7 @@ M: Eddie James <eajames@linux.ibm.com>
> L: linux-aspeed@lists.ozlabs.org (moderated for non-subscribers)
> S: Maintained
> F: Documentation/devicetree/bindings/interrupt-controller/aspeed,ast2xxx-scu-ic.txt
> +F: drivers/irqchip/irq-aspeed-scu-ic.c
> F: include/dt-bindings/interrupt-controller/aspeed-scu-ic.h
>
> ASPEED VIDEO ENGINE DRIVER
> diff --git a/drivers/irqchip/Makefile b/drivers/irqchip/Makefile
> index cc7c439..fce6b1d 100644
> --- a/drivers/irqchip/Makefile
> +++ b/drivers/irqchip/Makefile
> @@ -86,7 +86,7 @@ obj-$(CONFIG_MVEBU_PIC) += irq-mvebu-pic.o
> obj-$(CONFIG_MVEBU_SEI) += irq-mvebu-sei.o
> obj-$(CONFIG_LS_SCFG_MSI) += irq-ls-scfg-msi.o
> obj-$(CONFIG_EZNPS_GIC) += irq-eznps.o
> -obj-$(CONFIG_ARCH_ASPEED) += irq-aspeed-vic.o irq-aspeed-i2c-ic.o
> +obj-$(CONFIG_ARCH_ASPEED) += irq-aspeed-vic.o irq-aspeed-i2c-ic.o irq-aspeed-scu-ic.o
> obj-$(CONFIG_STM32_EXTI) += irq-stm32-exti.o
> obj-$(CONFIG_QCOM_IRQ_COMBINER) += qcom-irq-combiner.o
> obj-$(CONFIG_IRQ_UNIPHIER_AIDET) += irq-uniphier-aidet.o
> diff --git a/drivers/irqchip/irq-aspeed-scu-ic.c b/drivers/irqchip/irq-aspeed-scu-ic.c
> new file mode 100644
> index 0000000..a23802d
> --- /dev/null
> +++ b/drivers/irqchip/irq-aspeed-scu-ic.c
> @@ -0,0 +1,199 @@
> +// SPDX-License-Identifier: GPL-2.0+
> +/*
> + * Aspeed AST24XX, AST25XX, and AST26XX SCU Interrupt Controller
> + * Copyright 2019 IBM Corporation
> + *
> + * Eddie James <eajames@linux.ibm.com>
> + */
> +
> +#include <linux/bitops.h>
> +#include <linux/irq.h>
> +#include <linux/irqchip.h>
> +#include <linux/irqchip/chained_irq.h>
> +#include <linux/irqdomain.h>
> +#include <linux/of_address.h>
> +#include <linux/of_irq.h>
> +#include <linux/io.h>
> +
> +#define ASPEED_SCU_IC_SHIFT 0
> +#define ASPEED_SCU_IC_ENABLE GENMASK(6, ASPEED_SCU_IC_SHIFT)
> +#define ASPEED_SCU_IC_NUM_IRQS 7
> +#define ASPEED_SCU_IC_STATUS_SHIFT 16
> +
> +#define ASPEED_AST2600_SCU_IC0_SHIFT 0
> +#define ASPEED_AST2600_SCU_IC0_ENABLE \
> + GENMASK(5, ASPEED_AST2600_SCU_IC0_SHIFT)
> +#define ASPEED_AST2600_SCU_IC0_NUM_IRQS 6
> +
> +#define ASPEED_AST2600_SCU_IC1_SHIFT 4
> +#define ASPEED_AST2600_SCU_IC1_ENABLE \
> + GENMASK(5, ASPEED_AST2600_SCU_IC1_SHIFT)
> +#define ASPEED_AST2600_SCU_IC1_NUM_IRQS 2
> +
> +struct aspeed_scu_ic {
> + unsigned long irq_enable;
> + unsigned long irq_shift;
> + unsigned int num_irqs;
> + void __iomem *regs;
> + struct irq_domain *irq_domain;
> +};
> +
> +static void aspeed_scu_ic_irq_handler(struct irq_desc *desc)
> +{
> + unsigned int irq;
> + unsigned long bit;
> + unsigned long enabled;
> + unsigned long max;
> + unsigned long status;
> + struct aspeed_scu_ic *scu_ic = irq_desc_get_handler_data(desc);
> + struct irq_chip *chip = irq_desc_get_chip(desc);
> +
> + chained_irq_enter(chip, desc);
> +
> + status = readl(scu_ic->regs);

You may want to be easy on the interconnect and turn these readl/writel
into their relaxed version. This will remove a number of unnecessary
barriers.

> + enabled = status & scu_ic->irq_enable;
> + status = (status >> ASPEED_SCU_IC_STATUS_SHIFT) & enabled;

This masking looks weird. Does it mean that the status register is split
in half, with the two half serving different purposes? This requires
some documentation...

> +
> + bit = scu_ic->irq_shift;
> + max = scu_ic->num_irqs + bit;
> +
> + for_each_set_bit_from(bit, &status, max) {
> + irq = irq_find_mapping(scu_ic->irq_domain,
> + bit - scu_ic->irq_shift);
> + generic_handle_irq(irq);
> +
> + writel(enabled | BIT(bit + ASPEED_SCU_IC_STATUS_SHIFT),
> + scu_ic->regs);
> + }
> +
> + chained_irq_exit(chip, desc);
> +}
> +
> +static void aspeed_scu_ic_irq_mask(struct irq_data *data)
> +{
> + struct aspeed_scu_ic *scu_ic = irq_data_get_irq_chip_data(data);
> + unsigned long bit = BIT(data->hwirq + scu_ic->irq_shift);
> + unsigned long reg = readl(scu_ic->regs);
> +
> + writel((reg & ~bit) & scu_ic->irq_enable, scu_ic->regs);

What if you have another CPU masking or unmasking another interrupt at
the same time? These RMW operations need to be protected.

> +}
> +
> +static void aspeed_scu_ic_irq_unmask(struct irq_data *data)
> +{
> + struct aspeed_scu_ic *scu_ic = irq_data_get_irq_chip_data(data);
> + unsigned long bit = BIT(data->hwirq + scu_ic->irq_shift);
> + unsigned long reg = readl(scu_ic->regs);
> +
> + writel((reg | bit) & scu_ic->irq_enable, scu_ic->regs);
> +}
> +
> +struct irq_chip aspeed_scu_ic_chip = {
> + .name = "aspeed-scu-ic",
> + .irq_mask = aspeed_scu_ic_irq_mask,
> + .irq_unmask = aspeed_scu_ic_irq_unmask,

In an SMP system, you may want to provide an affinity callback returning
-EINVAL.

> +};
> +
> +static int aspeed_scu_ic_map(struct irq_domain *domain, unsigned int irq,
> + irq_hw_number_t hwirq)
> +{
> + irq_set_chip_and_handler(irq, &aspeed_scu_ic_chip, handle_simple_irq);
> + irq_set_chip_data(irq, domain->host_data);
> +
> + return 0;
> +}
> +
> +static const struct irq_domain_ops aspeed_scu_ic_domain_ops = {
> + .map = aspeed_scu_ic_map,
> +};
> +
> +static int aspeed_scu_ic_of_init_common(struct aspeed_scu_ic *scu_ic,
> + struct device_node *node)
> +{
> + int irq;
> + int rc = 0;
> +
> + scu_ic->regs = of_iomap(node, 0);
> + if (!scu_ic->regs) {
> + rc = -ENOMEM;
> + goto err_free;
> + }
> +
> + irq = irq_of_parse_and_map(node, 0);
> + if (irq < 0) {
> + rc = irq;
> + goto err_iounmap;
> + }
> +
> + scu_ic->irq_domain = irq_domain_add_linear(node, scu_ic->num_irqs,
> + &aspeed_scu_ic_domain_ops,
> + scu_ic);
> + if (!scu_ic->irq_domain) {
> + rc = -ENOMEM;
> + goto err_iounmap;
> + }
> +
> + irq_set_chained_handler_and_data(irq, aspeed_scu_ic_irq_handler,
> + scu_ic);
> +
> + return 0;
> +
> +err_iounmap:
> + iounmap(scu_ic->regs);
> +
> +err_free:
> + kfree(scu_ic);
> +
> + return rc;
> +}
> +
> +static int __init aspeed_scu_ic_of_init(struct device_node *node,
> + struct device_node *parent)
> +{
> + struct aspeed_scu_ic *scu_ic = kzalloc(sizeof(*scu_ic), GFP_KERNEL);
> +
> + if (!scu_ic)
> + return -ENOMEM;
> +
> + scu_ic->irq_enable = ASPEED_SCU_IC_ENABLE;
> + scu_ic->irq_shift = ASPEED_SCU_IC_SHIFT;
> + scu_ic->num_irqs = ASPEED_SCU_IC_NUM_IRQS;
> +
> + return aspeed_scu_ic_of_init_common(scu_ic, node);
> +}
> +
> +static int __init aspeed_ast2600_scu_ic0_of_init(struct device_node *node,
> + struct device_node *parent)
> +{
> + struct aspeed_scu_ic *scu_ic = kzalloc(sizeof(*scu_ic), GFP_KERNEL);
> +
> + if (!scu_ic)
> + return -ENOMEM;
> +
> + scu_ic->irq_enable = ASPEED_AST2600_SCU_IC0_ENABLE;
> + scu_ic->irq_shift = ASPEED_AST2600_SCU_IC0_SHIFT;
> + scu_ic->num_irqs = ASPEED_AST2600_SCU_IC0_NUM_IRQS;
> +
> + return aspeed_scu_ic_of_init_common(scu_ic, node);
> +}
> +
> +static int __init aspeed_ast2600_scu_ic1_of_init(struct device_node *node,
> + struct device_node *parent)
> +{
> + struct aspeed_scu_ic *scu_ic = kzalloc(sizeof(*scu_ic), GFP_KERNEL);
> +
> + if (!scu_ic)
> + return -ENOMEM;
> +
> + scu_ic->irq_enable = ASPEED_AST2600_SCU_IC1_ENABLE;
> + scu_ic->irq_shift = ASPEED_AST2600_SCU_IC1_SHIFT;
> + scu_ic->num_irqs = ASPEED_AST2600_SCU_IC1_NUM_IRQS;
> +
> + return aspeed_scu_ic_of_init_common(scu_ic, node);
> +}
> +
> +IRQCHIP_DECLARE(ast2400_scu_ic, "aspeed,ast2400-scu-ic", aspeed_scu_ic_of_init);
> +IRQCHIP_DECLARE(ast2500_scu_ic, "aspeed,ast2500-scu-ic", aspeed_scu_ic_of_init);
> +IRQCHIP_DECLARE(ast2600_scu_ic0, "aspeed,ast2600-scu-ic0",
> + aspeed_ast2600_scu_ic0_of_init);
> +IRQCHIP_DECLARE(ast2600_scu_ic1, "aspeed,ast2600-scu-ic1",
> + aspeed_ast2600_scu_ic1_of_init);
>

This otherwise looks nice and clean.

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