Re: [PATCH V8 3/3] irqchip: qcom: Add IRQ combiner driver

Agustin Vega-Frias
2016-12-13T15:23:04Z

On 2016-12-07 13:16, Marc Zyngier wrote:
> Hi Agustin,
>
> On 29/11/16 22:57, Agustin Vega-Frias wrote:
>> Driver for interrupt combiners in the Top-level Control and Status
>> Registers (TCSR) hardware block in Qualcomm Technologies chips.
>>
>> An interrupt combiner in this block combines a set of interrupts by
>> OR'ing the individual interrupt signals into a summary interrupt
>> signal routed to a parent interrupt controller, and provides read-
>> only, 32-bit registers to query the status of individual interrupts.
>> The status bit for IRQ n is bit (n % 32) within register (n / 32)
>> of the given combiner. Thus, each combiner can be described as a set
>> of register offsets and the number of IRQs managed.
>>
>> Signed-off-by: Agustin Vega-Frias <agustinv@codeaurora.org>
>> ---
>> drivers/irqchip/Kconfig | 8 +
>> drivers/irqchip/Makefile | 1 +
>> drivers/irqchip/qcom-irq-combiner.c | 337
>> ++++++++++++++++++++++++++++++++++++
>> 3 files changed, 346 insertions(+)
>> create mode 100644 drivers/irqchip/qcom-irq-combiner.c
>>
>> diff --git a/drivers/irqchip/Kconfig b/drivers/irqchip/Kconfig
>> index bc0af33..610f902 100644
>> --- a/drivers/irqchip/Kconfig
>> +++ b/drivers/irqchip/Kconfig
>> @@ -279,3 +279,11 @@ config EZNPS_GIC
>> config STM32_EXTI
>> bool
>> select IRQ_DOMAIN
>> +
>> +config QCOM_IRQ_COMBINER
>> + bool "QCOM IRQ combiner support"
>> + depends on ARCH_QCOM
>> + select IRQ_DOMAIN
>> + help
>> + Say yes here to add support for the IRQ combiner devices embedded
>> + in Qualcomm Technologies chips.
>> diff --git a/drivers/irqchip/Makefile b/drivers/irqchip/Makefile
>> index e4dbfc8..1818a0b 100644
>> --- a/drivers/irqchip/Makefile
>> +++ b/drivers/irqchip/Makefile
>> @@ -74,3 +74,4 @@ obj-$(CONFIG_LS_SCFG_MSI) += irq-ls-scfg-msi.o
>> obj-$(CONFIG_EZNPS_GIC) += irq-eznps.o
>> obj-$(CONFIG_ARCH_ASPEED) += irq-aspeed-vic.o
>> obj-$(CONFIG_STM32_EXTI) += irq-stm32-exti.o
>> +obj-$(CONFIG_QCOM_IRQ_COMBINER) += qcom-irq-combiner.o
>> diff --git a/drivers/irqchip/qcom-irq-combiner.c
>> b/drivers/irqchip/qcom-irq-combiner.c
>> new file mode 100644
>> index 0000000..fc25251
>> --- /dev/null
>> +++ b/drivers/irqchip/qcom-irq-combiner.c
>> @@ -0,0 +1,337 @@
>> +/* Copyright (c) 2015-2016, The Linux Foundation. All rights
>> reserved.
>> + *
>> + * This program is free software; you can redistribute it and/or
>> modify
>> + * it under the terms of the GNU General Public License version 2 and
>> + * only version 2 as published by the Free Software Foundation.
>> + *
>> + * This program is distributed in the hope that it will be useful,
>> + * but WITHOUT ANY WARRANTY; without even the implied warranty of
>> + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
>> + * GNU General Public License for more details.
>> + */
>> +
>> +/*
>> + * Driver for interrupt combiners in the Top-level Control and Status
>> + * Registers (TCSR) hardware block in Qualcomm Technologies chips.
>> + * An interrupt combiner in this block combines a set of interrupts
>> by
>> + * OR'ing the individual interrupt signals into a summary interrupt
>> + * signal routed to a parent interrupt controller, and provides read-
>> + * only, 32-bit registers to query the status of individual
>> interrupts.
>> + * The status bit for IRQ n is bit (n % 32) within register (n / 32)
>> + * of the given combiner. Thus, each combiner can be described as a
>> set
>> + * of register offsets and the number of IRQs managed.
>> + */
>> +
>> +#include <linux/acpi.h>
>> +#include <linux/irqchip/chained_irq.h>
>> +#include <linux/irqdomain.h>
>> +#include <linux/platform_device.h>
>> +
>> +#define REG_SIZE 32
>> +
>> +struct combiner_reg {
>> + void __iomem *addr;
>> + unsigned long mask;
>> +};
>> +
>> +struct combiner {
>> + struct irq_chip irq_chip;
>> + struct irq_domain *domain;
>> + int parent_irq;
>> + u32 nirqs;
>> + u32 nregs;
>> + struct combiner_reg regs[0];
>> +};
>> +
>> +static inline u32 irq_register(int irq)
>> +{
>> + return irq / REG_SIZE;
>> +}
>> +
>> +static inline u32 irq_bit(int irq)
>> +{
>> + return irq % REG_SIZE;
>> +
>> +}
>> +
>> +static inline int irq_nr(u32 reg, u32 bit)
>> +{
>> + return reg * REG_SIZE + bit;
>> +}
>> +
>> +/*
>> + * Handler for the cascaded IRQ.
>> + */
>> +static void combiner_handle_irq(struct irq_desc *desc)
>> +{
>> + struct combiner *combiner = irq_desc_get_handler_data(desc);
>> + struct irq_chip *chip = irq_desc_get_chip(desc);
>> + u32 reg;
>> +
>> + chained_irq_enter(chip, desc);
>> +
>> + for (reg = 0; reg < combiner->nregs; reg++) {
>> + int virq;
>> + int hwirq;
>> + u32 bit;
>> + u32 status;
>> +
>> + if (combiner->regs[reg].mask == 0)
>> + continue;
>> +
>> + status = readl_relaxed(combiner->regs[reg].addr);
>> + status &= combiner->regs[reg].mask;
>> +
>> + while (status) {
>> + bit = __ffs(status);
>> + status &= ~(1 << bit);
>> + hwirq = irq_nr(reg, bit);
>> + virq = irq_find_mapping(combiner->domain, hwirq);
>> + if (virq >= 0)
>> + generic_handle_irq(virq);
>> +
>> + }
>> + }
>> +
>> + chained_irq_exit(chip, desc);
>> +}
>> +
>> +/*
>> + * irqchip callbacks
>> + */
>> +
>> +static void combiner_irq_chip_mask_irq(struct irq_data *data)
>> +{
>> + struct combiner *combiner = irq_data_get_irq_chip_data(data);
>> + struct combiner_reg *reg = combiner->regs +
>> irq_register(data->hwirq);
>> +
>> + clear_bit(irq_bit(data->hwirq), &reg->mask);
>> +}
>> +
>> +static void combiner_irq_chip_unmask_irq(struct irq_data *data)
>> +{
>> + struct combiner *combiner = irq_data_get_irq_chip_data(data);
>> + struct combiner_reg *reg = combiner->regs +
>> irq_register(data->hwirq);
>> +
>> + set_bit(irq_bit(data->hwirq), &reg->mask);
>> +}
>> +
>> +/*
>> + * irq_domain_ops callbacks
>> + */
>> +
>> +static int combiner_irq_map(struct irq_domain *domain, unsigned int
>> irq,
>> + irq_hw_number_t hwirq)
>> +{
>> + struct combiner *combiner = domain->host_data;
>> +
>> + if (hwirq >= combiner->nirqs)
>> + return -EINVAL;
>> +
>> + irq_set_chip_and_handler(irq, &combiner->irq_chip,
>> handle_level_irq);
>> + irq_set_chip_data(irq, combiner);
>> + irq_set_parent(irq, combiner->parent_irq);
>
> Do you really need this irq_set_parent? This only makes sense if you're
> resending edge interrupts, and you seem to be level only.

OK, I'll take a look.

>
>> + irq_set_noprobe(irq);
>> + return 0;
>> +}
>> +
>> +static void combiner_irq_unmap(struct irq_domain *domain, unsigned
>> int irq)
>> +{
>> + irq_set_chip_and_handler(irq, NULL, NULL);
>> + irq_set_chip_data(irq, NULL);
>> + irq_set_parent(irq, -1);
>
> All of this should probably be replaced with a call to
> irq_domain_reset_irq_data().

Will do.

>
>> +}
>> +
>> +#ifdef CONFIG_IRQ_DOMAIN_HIERARCHY
>
> Is there any case where this is not valid?

What do you mean? Are you asking why is this under a preprocessor
conditional? If so I did it to be on the safe side since translate
in struct irq_domain_ops under that conditional.

>
>> +static int combiner_irq_translate(struct irq_domain *d, struct
>> irq_fwspec *fws,
>> + unsigned long *hwirq, unsigned int *type)
>> +{
>> + if (is_acpi_node(fws->fwnode)) {
>> + if (fws->param_count != 2)
>> + return -EINVAL;
>> +
>> + *hwirq = fws->param[0];
>> + *type = fws->param[1];
>
> Given that you're only handling level interrupts, shouldn't you abort
> if
> detecting an edge interrupt?

I'll add the check.

>
>> + return 0;
>> + }
>> +
>> + return -EINVAL;
>> +}
>> +#endif
>> +
>> +static const struct irq_domain_ops domain_ops = {
>> + .map = combiner_irq_map,
>> + .unmap = combiner_irq_unmap,
>> +#ifdef CONFIG_IRQ_DOMAIN_HIERARCHY
>> + .translate = combiner_irq_translate
>> +#endif
>> +};
>> +
>> +/*
>> + * Device probing
>> + */
>> +
>> +#ifdef CONFIG_ACPI
>> +
>> +static acpi_status count_registers_cb(struct acpi_resource *ares,
>> void *context)
>> +{
>> + int *count = context;
>> +
>> + if (ares->type == ACPI_RESOURCE_TYPE_GENERIC_REGISTER)
>> + ++(*count);
>> + return AE_OK;
>> +}
>> +
>> +static int count_registers(struct platform_device *pdev)
>> +{
>> + struct acpi_device *adev = ACPI_COMPANION(&pdev->dev);
>> + acpi_status status;
>> + int count = 0;
>> +
>> + if (!acpi_has_method(adev->handle, METHOD_NAME__CRS))
>> + return -EINVAL;
>> +
>> + status = acpi_walk_resources(adev->handle, METHOD_NAME__CRS,
>> + count_registers_cb, &count);
>> + if (ACPI_FAILURE(status))
>> + return -EINVAL;
>> + return count;
>> +}
>> +
>> +struct get_registers_context {
>> + struct device *dev;
>> + struct combiner *combiner;
>> + int err;
>> +};
>> +
>> +static acpi_status get_registers_cb(struct acpi_resource *ares, void
>> *context)
>> +{
>> + struct get_registers_context *ctx = context;
>> + struct acpi_resource_generic_register *reg;
>> + phys_addr_t paddr;
>> + void __iomem *vaddr;
>> +
>> + if (ares->type != ACPI_RESOURCE_TYPE_GENERIC_REGISTER)
>> + return AE_OK;
>> +
>> + reg = &ares->data.generic_reg;
>> + paddr = reg->address;
>> + if ((reg->space_id != ACPI_SPACE_MEM) ||
>> + (reg->bit_offset != 0) ||
>> + (reg->bit_width > REG_SIZE)) {
>> + dev_err(ctx->dev, "Bad register resource @%pa\n", &paddr);
>> + ctx->err = -EINVAL;
>> + return AE_ERROR;
>> + }
>> +
>> + vaddr = devm_ioremap(ctx->dev, reg->address, REG_SIZE);
>> + if (IS_ERR(vaddr)) {
>> + dev_err(ctx->dev, "Can't map register @%pa\n", &paddr);
>> + ctx->err = PTR_ERR(vaddr);
>> + return AE_ERROR;
>> + }
>> +
>> + ctx->combiner->regs[ctx->combiner->nregs].addr = vaddr;
>> + ctx->combiner->nirqs += reg->bit_width;
>> + ctx->combiner->nregs++;
>> + return AE_OK;
>> +}
>> +
>> +static int get_registers(struct platform_device *pdev, struct
>> combiner *comb)
>> +{
>> + struct acpi_device *adev = ACPI_COMPANION(&pdev->dev);
>> + acpi_status status;
>> + struct get_registers_context ctx;
>> +
>> + if (!acpi_has_method(adev->handle, METHOD_NAME__CRS))
>> + return -EINVAL;
>> +
>> + ctx.dev = &pdev->dev;
>> + ctx.combiner = comb;
>> + ctx.err = 0;
>> +
>> + status = acpi_walk_resources(adev->handle, METHOD_NAME__CRS,
>> + get_registers_cb, &ctx);
>> + if (ACPI_FAILURE(status))
>> + return ctx.err;
>> + return 0;
>> +}
>> +
>> +#else /* !CONFIG_ACPI */
>> +
>> +static int count_registers(struct platform_device *pdev)
>> +{
>> + return -EINVAL;
>> +}
>> +
>> +static int get_registers(struct platform_device *pdev, struct
>> combiner *comb)
>> +{
>> + return -EINVAL;
>> +}
>
> So this driver is obviously ACPI only. Can't you just get rid of these,
> of the #ifdef CONFIG_ACPI, and simply make it depend on ACPI?

Good point, will do.

>
>> +
>> +#endif
>> +
>> +static int __init combiner_probe(struct platform_device *pdev)
>> +{
>> + struct combiner *combiner;
>> + size_t alloc_sz;
>> + u32 nregs;
>> + int err;
>> +
>> + nregs = count_registers(pdev);
>> + if (nregs <= 0) {
>> + dev_err(&pdev->dev, "Error reading register resources\n");
>> + return -EINVAL;
>> + }
>> +
>> + alloc_sz = sizeof(*combiner) + sizeof(struct combiner_reg) * nregs;
>> + combiner = devm_kzalloc(&pdev->dev, alloc_sz, GFP_KERNEL);
>> + if (!combiner)
>> + return -ENOMEM;
>> +
>> + err = get_registers(pdev, combiner);
>> + if (err < 0)
>> + return err;
>> +
>> + combiner->parent_irq = platform_get_irq(pdev, 0);
>> + if (combiner->parent_irq <= 0) {
>> + dev_err(&pdev->dev, "Error getting IRQ resource\n");
>> + return -EINVAL;
>
> Can you ever get in a situation where it'd be more sensible to return
> -EPROBE_DEFER? I'm thinking of a case where you'd have this irq chip
> cascaded into another one, which is not present yet?

Not in the current architecture, but I agree it would accommodate other
use cases. I will change it to return -EPROBE_DEFER.

>
>> + }
>> +
>> + combiner->domain = irq_domain_create_linear(
>> + pdev->dev.fwnode, combiner->nirqs, &domain_ops, combiner);
>
> On a single line, please. Do no listen to the checkpatch police that
> will tell you otherwise. It really hurt my eyes to see this opening
> bracket and *nothing* after that.

Will do.

>
>> + if (!combiner->domain)
>> + /* Errors printed by irq_domain_create_linear */
>> + return -ENODEV;
>> +
>> + irq_set_chained_handler_and_data(combiner->parent_irq,
>> + combiner_handle_irq, combiner);
>> + combiner->irq_chip.irq_mask = combiner_irq_chip_mask_irq;
>> + combiner->irq_chip.irq_unmask = combiner_irq_chip_unmask_irq;
>> + combiner->irq_chip.name = pdev->name;
>
> Arghh. Please don't do that. Once you've called irq_set_chained_*, the
> interrupt is live, and can be requested. Unlikely, but still. In
> general, feeding uninitialized data to a function is pretty bad.
>
> Also, do you really need to show pdev->name in /proc/cpuinfo? Just make
> the irq_chip structure static, outside of combiner, and have "QCOM80B1"
> (or something of your liking) as the name once and for all.

I'll look at this.

Thanks for the detailed feedback.

Agustin.

>
>> +
>> + dev_info(&pdev->dev, "Initialized with [p=%d,n=%d,r=%p]\n",
>> + combiner->parent_irq, combiner->nirqs, combiner->regs[0].addr);
>> + return 0;
>> +}
>> +
>> +static const struct acpi_device_id qcom_irq_combiner_acpi_match[] = {
>> + { "QCOM80B1", },
>> + { }
>> +};
>> +
>> +static struct platform_driver qcom_irq_combiner_probe = {
>> + .driver = {
>> + .name = "qcom-irq-combiner",
>> + .owner = THIS_MODULE,
>> + .acpi_match_table = ACPI_PTR(qcom_irq_combiner_acpi_match),
>> + },
>> + .probe = combiner_probe,
>> +};
>> +
>> +static int __init register_qcom_irq_combiner(void)
>> +{
>> + return platform_driver_register(&qcom_irq_combiner_probe);
>> +}
>> +device_initcall(register_qcom_irq_combiner);
>>
>
> Thanks,
>
> M.
> --
> Jazz is not dead. It just smells funny...

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