Re: [PATCH 2/2] MIPS: bmips: Add bcm63168-l1 interrupt controller

[Jonas Gorski]

On Sun, Nov 15, 2015 at 5:53 PM, Simon Arlott <simon@xxxxxxxxxxx> wrote:
> Add the BCM63168 interrupt controller based on the SMP-capable BCM7038
> and the BCM3380 but with packed interrupt registers.
>
> Add the BCM63168 interrupt controller to a list with the existing BCM7038
> so that interrupts on CPU1 are not ignored.
>
> Update the maintainers file list for BMIPS to include this driver.
>
> Signed-off-by: Simon Arlott <simon@xxxxxxxxxxx>
> ---
>  MAINTAINERS                       |   1 +
>  arch/mips/Kconfig                 |   1 +
>  arch/mips/bmips/irq.c             |  10 +-
>  drivers/irqchip/Kconfig           |   5 +
>  drivers/irqchip/Makefile          |   1 +
>  drivers/irqchip/irq-bcm63168-l1.c | 372 ++++++++++++++++++++++++++++++++++++++
>  6 files changed, 388 insertions(+), 2 deletions(-)
>  create mode 100644 drivers/irqchip/irq-bcm63168-l1.c
>
> diff --git a/MAINTAINERS b/MAINTAINERS
> index e9caa4b..63bf54a 100644
> --- a/MAINTAINERS
> +++ b/MAINTAINERS
> @@ -2373,6 +2373,7 @@ F:        arch/mips/bmips/*
>  F:     arch/mips/include/asm/mach-bmips/*
>  F:     arch/mips/kernel/*bmips*
>  F:     arch/mips/boot/dts/brcm/bcm*.dts*
> +F:     drivers/irqchip/irq-bcm63*
>  F:     drivers/irqchip/irq-bcm7*
>  F:     drivers/irqchip/irq-brcmstb*
>
> diff --git a/arch/mips/Kconfig b/arch/mips/Kconfig
> index e3aa5b0..1a8decd 100644
> --- a/arch/mips/Kconfig
> +++ b/arch/mips/Kconfig
> @@ -149,6 +149,7 @@ config BMIPS_GENERIC
>         select CSRC_R4K
>         select SYNC_R4K
>         select COMMON_CLK
> +       select BCM63168_L1_IRQ
>         select BCM7038_L1_IRQ
>         select BCM7120_L2_IRQ
>         select BRCMSTB_L2_IRQ
> diff --git a/arch/mips/bmips/irq.c b/arch/mips/bmips/irq.c
> index e7fc6f934..7983cef 100644
> --- a/arch/mips/bmips/irq.c
> +++ b/arch/mips/bmips/irq.c
> @@ -15,6 +15,12 @@
>  #include <asm/irq_cpu.h>
>  #include <asm/time.h>
>
> +static const struct of_device_id smp_intc_dt_match[] = {
> +       { .compatible = "brcm,bcm7038-l1-intc" },
> +       { .compatible = "brcm,bcm63168-l1-intc" },
> +       {}
> +};
> +
>  unsigned int get_c0_compare_int(void)
>  {
>         return CP0_LEGACY_COMPARE_IRQ;
> @@ -24,8 +30,8 @@ void __init arch_init_irq(void)
>  {
>         struct device_node *dn;
>
> -       /* Only the STB (bcm7038) controller supports SMP IRQ affinity */
> -       dn = of_find_compatible_node(NULL, NULL, "brcm,bcm7038-l1-intc");
> +       /* Only these controllers support SMP IRQ affinity */
> +       dn = of_find_matching_node(NULL, smp_intc_dt_match);
>         if (dn)
>                 of_node_put(dn);
>         else
> diff --git a/drivers/irqchip/Kconfig b/drivers/irqchip/Kconfig
> index 4d7294e..82ce318 100644
> --- a/drivers/irqchip/Kconfig
> +++ b/drivers/irqchip/Kconfig
> @@ -65,6 +65,11 @@ config I8259
>         bool
>         select IRQ_DOMAIN
>
> +config BCM63168_L1_IRQ
> +       bool
> +       select GENERIC_IRQ_CHIP
> +       select IRQ_DOMAIN
> +
>  config BCM7038_L1_IRQ
>         bool
>         select GENERIC_IRQ_CHIP
> diff --git a/drivers/irqchip/Makefile b/drivers/irqchip/Makefile
> index 177f78f..a3a21e2 100644
> --- a/drivers/irqchip/Makefile
> +++ b/drivers/irqchip/Makefile
> @@ -43,6 +43,7 @@ obj-$(CONFIG_XTENSA)                  += irq-xtensa-pic.o
>  obj-$(CONFIG_XTENSA_MX)                        += irq-xtensa-mx.o
>  obj-$(CONFIG_IRQ_CROSSBAR)             += irq-crossbar.o
>  obj-$(CONFIG_SOC_VF610)                        += irq-vf610-mscm-ir.o
> +obj-$(CONFIG_BCM63168_L1_IRQ)          += irq-bcm63168-l1.o
>  obj-$(CONFIG_BCM7038_L1_IRQ)           += irq-bcm7038-l1.o
>  obj-$(CONFIG_BCM7120_L2_IRQ)           += irq-bcm7120-l2.o
>  obj-$(CONFIG_BRCMSTB_L2_IRQ)           += irq-brcmstb-l2.o
> diff --git a/drivers/irqchip/irq-bcm63168-l1.c b/drivers/irqchip/irq-bcm63168-l1.c
> new file mode 100644
> index 0000000..5a144af
> --- /dev/null
> +++ b/drivers/irqchip/irq-bcm63168-l1.c
> @@ -0,0 +1,372 @@
> +/*
> + * Broadcom BCM63168 style Level 1 interrupt controller driver
> + *
> + * Copyright (C) 2014 Broadcom Corporation
> + * Copyright 2015 Simon Arlott
> + *
> + * This program is free software; you can redistribute it and/or modify
> + * it under the terms of the GNU General Public License version 2 as
> + * published by the Free Software Foundation.
> + *
> + * This is based on the BCM7038 (which supports SMP) but with a single
> + * enable register instead of separate mask/set/clear registers.
> + *
> + * The BCM3380 has a similar mask/status register layout, but each pair
> + * of words is at separate locations (and SMP is not supported).
> + *
> + * ENABLE/STATUS words are packed next to each other for each CPU:
> + *
> + * 6368:
> + *   0x1000_0020: CPU0_W0_ENABLE
> + *   0x1000_0024: CPU0_W1_ENABLE
> + *   0x1000_0028: CPU0_W0_STATUS               IRQs 31-63
> + *   0x1000_002c: CPU0_W1_STATUS               IRQs 0-31
> + *   0x1000_0030: CPU1_W0_ENABLE
> + *   0x1000_0034: CPU1_W1_ENABLE
> + *   0x1000_0038: CPU1_W0_STATUS               IRQs 31-63
> + *   0x1000_003c: CPU1_W1_STATUS               IRQs 0-31
> + *
> + * 63168:
> + *   0x1000_0020: CPU0_W0_ENABLE
> + *   0x1000_0024: CPU0_W1_ENABLE
> + *   0x1000_0028: CPU0_W2_ENABLE
> + *   0x1000_002c: CPU0_W3_ENABLE
> + *   0x1000_0030: CPU0_W0_STATUS       IRQs 96-127
> + *   0x1000_0034: CPU0_W1_STATUS       IRQs 64-95
> + *   0x1000_0038: CPU0_W2_STATUS       IRQs 32-63
> + *   0x1000_003c: CPU0_W3_STATUS       IRQs 0-31
> + *   0x1000_0040: CPU1_W0_ENABLE
> + *   0x1000_0044: CPU1_W1_ENABLE
> + *   0x1000_0048: CPU1_W2_ENABLE
> + *   0x1000_004c: CPU1_W3_ENABLE
> + *   0x1000_0050: CPU1_W0_STATUS       IRQs 96-127
> + *   0x1000_0054: CPU1_W1_STATUS       IRQs 64-95
> + *   0x1000_0058: CPU1_W2_STATUS       IRQs 32-63
> + *   0x1000_005c: CPU1_W3_STATUS       IRQs 0-31
> + *
> + * IRQs are numbered in CPU native endian order
> + * (which is big-endian in these examples)
> + */
> +
> +#define pr_fmt(fmt)    KBUILD_MODNAME  ": " fmt
> +
> +#include <linux/bitops.h>
> +#include <linux/cpumask.h>
> +#include <linux/kconfig.h>
> +#include <linux/kernel.h>
> +#include <linux/init.h>
> +#include <linux/interrupt.h>
> +#include <linux/io.h>
> +#include <linux/ioport.h>
> +#include <linux/irq.h>
> +#include <linux/irqdomain.h>
> +#include <linux/module.h>
> +#include <linux/of.h>
> +#include <linux/of_irq.h>
> +#include <linux/of_address.h>
> +#include <linux/of_platform.h>
> +#include <linux/platform_device.h>
> +#include <linux/slab.h>
> +#include <linux/smp.h>
> +#include <linux/types.h>
> +#include <linux/irqchip.h>
> +#include <linux/irqchip/chained_irq.h>
> +
> +#define IRQS_PER_WORD          32
> +#define REG_BYTES_PER_IRQ_WORD (sizeof(u32) * 2)
> +#define MAX_WORDS              4
> +
> +struct bcm63168_l1_cpu;
> +
> +struct bcm63168_l1_chip {
> +       raw_spinlock_t          lock[MAX_WORDS];
> +       unsigned int            n_words;
> +       struct irq_domain       *domain;
> +       struct cpumask          cpumask;
> +       struct bcm63168_l1_cpu  *cpus[NR_CPUS];
> +};
> +
> +struct bcm63168_l1_cpu {
> +       void __iomem            *map_base;
> +       unsigned int            parent_irq;
> +       u32                     enable_cache[];
> +};
> +
> +static inline unsigned int reg_enable(struct bcm63168_l1_chip *intc,
> +                                          unsigned int word)
> +{
> +#ifdef __BIG_ENDIAN
> +       return (1 * intc->n_words - word - 1) * sizeof(u32);
> +#else
> +       return (0 * intc->n_words + word) * sizeof(u32);

Huh, do the words really change the order when running in LE? I would
have expected
to each 32-bit word to contain the same interrupts, just bit-order reversed.

> +#endif
> +}
> +
> +static inline unsigned int reg_status(struct bcm63168_l1_chip *intc,
> +                                     unsigned int word)
> +{
> +#ifdef __BIG_ENDIAN
> +       return (2 * intc->n_words - word - 1) * sizeof(u32);
> +#else
> +       return (1 * intc->n_words + word) * sizeof(u32);
> +#endif
> +}
> +
> +static inline unsigned int cpu_for_irq(struct bcm63168_l1_chip *intc,
> +                                       struct irq_data *d)
> +{
> +       return cpumask_first_and(&intc->cpumask, irq_data_get_affinity_mask(d));
> +}
> +
> +static void bcm63168_l1_irq_handle(struct irq_desc *desc)
> +{
> +       struct bcm63168_l1_chip *intc = irq_desc_get_handler_data(desc);
> +       struct bcm63168_l1_cpu *cpu;
> +       struct irq_chip *chip = irq_desc_get_chip(desc);
> +       unsigned int idx;
> +
> +#ifdef CONFIG_SMP
> +       cpu = intc->cpus[cpu_logical_map(smp_processor_id())];
> +#else
> +       cpu = intc->cpus[0];
> +#endif

This looks expensive, can they change during runtime? If not, maybe
just assign intc->cpus[] accordingly at probe time, so you can just do
intc->cpus[smp_processor_id()] without any #ifdefs.

> +
> +       chained_irq_enter(chip, desc);
> +
> +       for (idx = 0; idx < intc->n_words; idx++) {
> +               int base = idx * IRQS_PER_WORD;
> +               unsigned long pending;
> +               irq_hw_number_t hwirq;
> +               unsigned int irq;
> +
> +               pending = __raw_readl(cpu->map_base + reg_status(intc, idx));
> +               pending &= __raw_readl(cpu->map_base + reg_enable(intc, idx));

Is it save to access the registers without any locking? 7038-l1
doesn't think so.

> +
> +               for_each_set_bit(hwirq, &pending, IRQS_PER_WORD) {
> +                       irq = irq_linear_revmap(intc->domain, base + hwirq);
> +                       if (irq)
> +                               do_IRQ(irq);
> +                       else
> +                               spurious_interrupt();
> +               }
> +       }
> +
> +       chained_irq_exit(chip, desc);
> +}
> +
> +static inline void __bcm63168_l1_unmask(struct irq_data *d)
> +{
> +       struct bcm63168_l1_chip *intc = irq_data_get_irq_chip_data(d);
> +       u32 word = d->hwirq / IRQS_PER_WORD;
> +       u32 mask = BIT(d->hwirq % IRQS_PER_WORD);
> +       unsigned int cpu_idx = cpu_for_irq(intc, d);
> +
> +       intc->cpus[cpu_idx]->enable_cache[word] |= mask;
> +       __raw_writel(intc->cpus[cpu_idx]->enable_cache[word],
> +               intc->cpus[cpu_idx]->map_base + reg_enable(intc, word));
> +}
> +
> +static inline void __bcm63168_l1_mask(struct irq_data *d)
> +{
> +       struct bcm63168_l1_chip *intc = irq_data_get_irq_chip_data(d);
> +       u32 word = d->hwirq / IRQS_PER_WORD;
> +       u32 mask = BIT(d->hwirq % IRQS_PER_WORD);
> +       unsigned int cpu_idx = cpu_for_irq(intc, d);
> +
> +       intc->cpus[cpu_idx]->enable_cache[word] &= ~mask;
> +       __raw_writel(intc->cpus[cpu_idx]->enable_cache[word],
> +               intc->cpus[cpu_idx]->map_base + reg_enable(intc, word));
> +}
> +
> +static void bcm63168_l1_unmask(struct irq_data *d)
> +{
> +       struct bcm63168_l1_chip *intc = irq_data_get_irq_chip_data(d);
> +       u32 word = d->hwirq / IRQS_PER_WORD;
> +       unsigned long flags;
> +
> +       raw_spin_lock_irqsave(&intc->lock[word], flags);
> +       __bcm63168_l1_unmask(d);
> +       raw_spin_unlock_irqrestore(&intc->lock[word], flags);
> +}
> +
> +static void bcm63168_l1_mask(struct irq_data *d)
> +{
> +       struct bcm63168_l1_chip *intc = irq_data_get_irq_chip_data(d);
> +       u32 word = d->hwirq / IRQS_PER_WORD;
> +       unsigned long flags;
> +
> +       raw_spin_lock_irqsave(&intc->lock[word], flags);
> +       __bcm63168_l1_mask(d);
> +       raw_spin_unlock_irqrestore(&intc->lock[word], flags);
> +}
> +
> +static int bcm63168_l1_set_affinity(struct irq_data *d,
> +                                  const struct cpumask *dest,
> +                                  bool force)
> +{
> +       struct bcm63168_l1_chip *intc = irq_data_get_irq_chip_data(d);
> +       u32 word = d->hwirq / IRQS_PER_WORD;
> +       u32 mask = BIT(d->hwirq % IRQS_PER_WORD);
> +       unsigned int old_cpu = cpu_for_irq(intc, d);
> +       unsigned int new_cpu;
> +       struct cpumask valid;
> +       unsigned long flags;
> +       bool enabled;
> +
> +       if (!cpumask_and(&valid, &intc->cpumask, dest))
> +               return -EINVAL;
> +
> +       new_cpu = cpumask_any_and(&valid, cpu_online_mask);
> +       if (new_cpu >= nr_cpu_ids)
> +               return -EINVAL;
> +
> +       dest = cpumask_of(new_cpu);
> +
> +       raw_spin_lock_irqsave(&intc->lock[word], flags);
> +       if (old_cpu != new_cpu) {
> +               enabled = intc->cpus[old_cpu]->enable_cache[word] & mask;
> +               if (enabled)
> +                       __bcm63168_l1_mask(d);
> +               cpumask_copy(irq_data_get_affinity_mask(d), dest);
> +               if (enabled)
> +                       __bcm63168_l1_unmask(d);
> +       } else {
> +               cpumask_copy(irq_data_get_affinity_mask(d), dest);
> +       }
> +       raw_spin_unlock_irqrestore(&intc->lock[word], flags);
> +
> +       return IRQ_SET_MASK_OK_NOCOPY;
> +}
> +
> +static int __init bcm63168_l1_init_one(struct device_node *dn,
> +                                     unsigned int idx,
> +                                     struct bcm63168_l1_chip *intc)
> +{
> +       struct resource res;
> +       resource_size_t sz;
> +       struct bcm63168_l1_cpu *cpu;
> +       unsigned int i, n_words;
> +
> +       if (of_address_to_resource(dn, idx, &res))
> +               return -EINVAL;
> +       sz = resource_size(&res);
> +       n_words = sz / REG_BYTES_PER_IRQ_WORD;
> +
> +       if (n_words > MAX_WORDS)
> +               return -EINVAL;
> +       else if (!intc->n_words)
> +               intc->n_words = n_words;
> +       else if (intc->n_words != n_words)
> +               return -EINVAL;
> +
> +       cpu = intc->cpus[idx] = kzalloc(sizeof(*cpu) + n_words * sizeof(u32),
> +                                       GFP_KERNEL);
> +       if (!cpu)
> +               return -ENOMEM;
> +
> +       cpu->map_base = ioremap(res.start, sz);
> +       if (!cpu->map_base)
> +               return -ENOMEM;
> +
> +       for (i = 0; i < n_words; i++) {
> +               cpu->enable_cache[i] = 0;
> +               __raw_writel(0, cpu->map_base + reg_enable(intc, i));
> +       }
> +
> +       cpu->parent_irq = irq_of_parse_and_map(dn, idx);
> +       if (!cpu->parent_irq) {
> +               pr_err("failed to map parent interrupt %d\n", cpu->parent_irq);
> +               return -EINVAL;
> +       }
> +       irq_set_chained_handler_and_data(cpu->parent_irq,
> +                                               bcm63168_l1_irq_handle, intc);
> +
> +       return 0;
> +}
> +
> +static struct irq_chip bcm63168_l1_irq_chip = {
> +       .name                   = "bcm63168-l1",
> +       .irq_mask               = bcm63168_l1_mask,
> +       .irq_unmask             = bcm63168_l1_unmask,
> +       .irq_set_affinity       = bcm63168_l1_set_affinity,
> +};

You are already allocing memory, why not alloc this one as well?

> +
> +static int bcm63168_l1_map(struct irq_domain *d, unsigned int virq,
> +                         irq_hw_number_t hw_irq)
> +{
> +       irq_set_chip_and_handler(virq,
> +               &bcm63168_l1_irq_chip, handle_percpu_irq);
> +       irq_set_chip_data(virq, d->host_data);
> +       return 0;
> +}
> +
> +static const struct irq_domain_ops bcm63168_l1_domain_ops = {
> +       .xlate                  = irq_domain_xlate_onecell,
> +       .map                    = bcm63168_l1_map,
> +};
> +
> +static int __init bcm63168_l1_of_init(struct device_node *dn,
> +                             struct device_node *parent)
> +{
> +       struct bcm63168_l1_chip *intc;
> +       unsigned int idx;
> +       int ret;
> +
> +       intc = kzalloc(sizeof(*intc), GFP_KERNEL);
> +       if (!intc)
> +               return -ENOMEM;
> +
> +       cpumask_clear(&intc->cpumask);

intc->cpumask is already cleared since kzalloc'd.

> +
> +       for_each_possible_cpu(idx) {
> +               ret = bcm63168_l1_init_one(dn, idx, intc);
> +               if (ret)
> +                       pr_err("failed to init intc L1 for cpu %d: %d\n",
> +                               idx, ret);
> +               else
> +                       cpumask_set_cpu(idx, &intc->cpumask);
> +       }
> +
> +       if (!cpumask_weight(&intc->cpumask)) {
> +               ret = -ENODEV;
> +               goto out_free;
> +       }
> +
> +       for (idx = 0; idx < intc->n_words; idx++)
> +               raw_spin_lock_init(&intc->lock[idx]);

Do you really need a spinlock for each word?

> +
> +       intc->domain = irq_domain_add_linear(dn, IRQS_PER_WORD * intc->n_words,
> +                                            &bcm63168_l1_domain_ops,
> +                                            intc);
> +       if (!intc->domain) {
> +               ret = -ENOMEM;
> +               goto out_unmap;
> +       }
> +
> +       pr_info("registered BCM63168 L1 intc (IRQs: %d)\n",
> +                       IRQS_PER_WORD * intc->n_words);
> +       for_each_cpu(idx, &intc->cpumask) {
> +               struct bcm63168_l1_cpu *cpu = intc->cpus[idx];
> +
> +               pr_info("  CPU%u at MMIO 0x%p (irq = %d)\n", idx,
> +                               cpu->map_base, cpu->parent_irq);
> +       }
> +
> +       return 0;
> +
> +out_unmap:
> +       for_each_possible_cpu(idx) {
> +               struct bcm63168_l1_cpu *cpu = intc->cpus[idx];
> +
> +               if (cpu) {
> +                       if (cpu->map_base)
> +                               iounmap(cpu->map_base);
> +                       kfree(cpu);
> +               }
> +       }
> +out_free:
> +       kfree(intc);
> +       return ret;
> +}
> +
> +IRQCHIP_DECLARE(bcm63168_l1, "brcm,bcm63168-l1-intc", bcm63168_l1_of_init);
> --
> 2.1.4


Jonas
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