[PATCH V11 3/3] irqchip: qcom: Add IRQ combiner driver
Agustin Vega-Frias
agustinv at codeaurora.org
Thu Feb 2 14:20:28 PST 2017
Hi Andy,
On 2017-01-25 19:44, Andy Shevchenko wrote:
> On Fri, Jan 20, 2017 at 4:34 AM, Agustin Vega-Frias
> <agustinv at codeaurora.org> 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.
>
>> +static inline u32 irq_register(int irq)
>> +{
>> + return irq / REG_SIZE;
>> +}
>> +
>> +static inline u32 irq_bit(int irq)
>> +{
>> + return irq % REG_SIZE;
>> +
>> +}
>
> Besides extra line I do not see a benefit of those helpers. On first
> glance they even increase characters to type.
>
Will remove these.
>> +static inline int irq_nr(u32 reg, u32 bit)
>> +{
>> + return reg * REG_SIZE + bit;
>> +}
>
> This one might make sense.
>
>> +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;
>> +
>> + bit = readl_relaxed(combiner->regs[reg].addr);
>> + status = bit & combiner->regs[reg].enabled;
>> + if (!status)
>> + pr_warn_ratelimited("Unexpected IRQ on CPU%d:
>> (%08x %08lx %p)\n",
>> + smp_processor_id(), bit,
>> +
>> combiner->regs[reg].enabled,
>> + combiner->regs[reg].addr);
>> +
>
>> + while (status) {
>> + bit = __ffs(status);
>> + status &= ~(1 << bit);
>
> Interesting way of for_each_set_bit() ?
>
I'm leaving this as-is since in arm64 using __ffs can be optimized
better by using the bic instruction.
>> + 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
>> + */
>
> Useless.
>
Will remove
>> +/*
>> + * irq_domain_ops callbacks
>> + */
>
> Ditto.
>
Will remove
>> +/*
>> + * Device probing
>> + */
>
> Ditto.
>
Will remove
>> +static acpi_status count_registers_cb(struct acpi_resource *ares,
>> void *context)
>> +{
>> + int *count = context;
>
> I would consider to define a struct. It would be easy to extend if
> needed and...
>
The intent here is always to get the count so I don't see value
in adding the struct.
>> +
>> + if (ares->type == ACPI_RESOURCE_TYPE_GENERIC_REGISTER)
>> + ++(*count);
>
> ...allows not to use such of constructions. (I think above is
> equivalent to ++*count).
>
IMHO having the parentheses makes the code clearer.
>> + return AE_OK;
>
>> +}
>> +
>> +static int count_registers(struct platform_device *pdev)
>> +{
>> + struct acpi_device *adev = ACPI_COMPANION(&pdev->dev);
>
> You don't use adev, so, ACPI_HANDLE() ?
>
Will change
>> + 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;
>> +}
>
> Oh, since you are using this just as a helper to get count first, why
> not to combine this in one callback?
> What's the benefit of separation?
>
This is because we do an allocation based on the count first.
>> +
>> +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;
>> + }
>
> This all sounds to me like an OperationalRegion. But I'm not sure it's
> suitable here.
> Do you have ACPI table carved in stone?
>
I decided to go with registers because in some cases these might be non-
contiguous.
>> +
>> + 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;
>> +}
>> +
>> +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 -EPROBE_DEFER;
>> + }
>> +
>> + combiner->domain = irq_domain_create_linear(pdev->dev.fwnode,
>> combiner->nirqs,
>> + &domain_ops,
>> combiner);
>> + 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);
>> +
>> + 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_ids[]
>> __dsdt_irqchip = {
>> + { "QCOM80B1", },
>> + { }
>> +};
>> +
>> +static struct platform_driver qcom_irq_combiner_probe = {
>> + .driver = {
>> + .name = "qcom-irq-combiner",
>
>> + .owner = THIS_MODULE,
>
> Do you still need this?
>
Will remove
Thanks,
Agustin
>> + .acpi_match_table = ACPI_PTR(qcom_irq_combiner_ids),
>> + },
>
> --
> With Best Regards,
> Andy Shevchenko
--
Qualcomm Datacenter Technologies, Inc. on behalf of the Qualcomm
Technologies, Inc.
Qualcomm Technologies, Inc. is a member of the Code Aurora Forum, a
Linux Foundation Collaborative Project.
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