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

Eddie James
2019-09-24T18:11:25Z

On 9/24/19 11:47 AM, Marc Zyngier wrote:
> 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.

Sure thing.

>
>> + 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...

That's correct. The top half is the status bits and the bottom half is
the enable bits. I'll add some comments.

>
>> +
>> + 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.

Good point, thanks.

>
>> +}
>> +
>> +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.

OK.

>
>> +};
>> +
>> +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.

Thanks for the quick review!

Eddie

>
> M.