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// SPDX-License-Identifier: GPL-2.0
/*
* Copyright (C) 2017 SiFive
* Copyright (C) 2018 Christoph Hellwig
*/
#define pr_fmt(fmt) "plic: " fmt
#include <linux/cpu.h>
#include <linux/interrupt.h>
#include <linux/io.h>
#include <linux/irq.h>
#include <linux/irqchip.h>
#include <linux/irqdomain.h>
#include <linux/module.h>
#include <linux/of.h>
#include <linux/of_address.h>
#include <linux/of_irq.h>
#include <linux/platform_device.h>
#include <linux/spinlock.h>
#include <asm/smp.h>
/*
* This driver implements a version of the RISC-V PLIC with the actual layout
* specified in chapter 8 of the SiFive U5 Coreplex Series Manual:
*
* https://static.dev.sifive.com/U54-MC-RVCoreIP.pdf
*
* The largest number supported by devices marked as 'sifive,plic-1.0.0', is
* 1024, of which device 0 is defined as non-existent by the RISC-V Privileged
* Spec.
*/
#define MAX_DEVICES 1024
#define MAX_CONTEXTS 15872
/*
* Each interrupt source has a priority register associated with it.
* We always hardwire it to one in Linux.
*/
#define PRIORITY_BASE 0
#define PRIORITY_PER_ID 4
/*
* Each hart context has a vector of interrupt enable bits associated with it.
* There's one bit for each interrupt source.
*/
#define ENABLE_BASE 0x2000
#define ENABLE_PER_HART 0x80
/*
* Each hart context has a set of control registers associated with it. Right
* now there's only two: a source priority threshold over which the hart will
* take an interrupt, and a register to claim interrupts.
*/
#define CONTEXT_BASE 0x200000
#define CONTEXT_PER_HART 0x1000
#define CONTEXT_THRESHOLD 0x00
#define CONTEXT_CLAIM 0x04
#define PLIC_DISABLE_THRESHOLD 0x7
#define PLIC_ENABLE_THRESHOLD 0
struct plic_priv {
struct cpumask lmask;
struct irq_domain *irqdomain;
void __iomem *regs;
};
struct plic_handler {
bool present;
void __iomem *hart_base;
/*
* Protect mask operations on the registers given that we can't
* assume atomic memory operations work on them.
*/
raw_spinlock_t enable_lock;
void __iomem *enable_base;
struct plic_priv *priv;
};
static DEFINE_PER_CPU(struct plic_handler, plic_handlers);
static inline void plic_toggle(struct plic_handler *handler,
int hwirq, int enable)
{
u32 __iomem *reg = handler->enable_base + (hwirq / 32) * sizeof(u32);
u32 hwirq_mask = 1 << (hwirq % 32);
raw_spin_lock(&handler->enable_lock);
if (enable)
writel(readl(reg) | hwirq_mask, reg);
else
writel(readl(reg) & ~hwirq_mask, reg);
raw_spin_unlock(&handler->enable_lock);
}
static inline void plic_irq_toggle(const struct cpumask *mask,
struct irq_data *d, int enable)
{
int cpu;
struct plic_priv *priv = irq_get_chip_data(d->irq);
writel(enable, priv->regs + PRIORITY_BASE + d->hwirq * PRIORITY_PER_ID);
for_each_cpu(cpu, mask) {
struct plic_handler *handler = per_cpu_ptr(&plic_handlers, cpu);
if (handler->present &&
cpumask_test_cpu(cpu, &handler->priv->lmask))
plic_toggle(handler, d->hwirq, enable);
}
}
static void plic_irq_unmask(struct irq_data *d)
{
struct cpumask amask;
unsigned int cpu;
struct plic_priv *priv = irq_get_chip_data(d->irq);
cpumask_and(&amask, &priv->lmask, cpu_online_mask);
cpu = cpumask_any_and(irq_data_get_affinity_mask(d),
&amask);
if (WARN_ON_ONCE(cpu >= nr_cpu_ids))
return;
plic_irq_toggle(cpumask_of(cpu), d, 1);
}
static void plic_irq_mask(struct irq_data *d)
{
struct plic_priv *priv = irq_get_chip_data(d->irq);
plic_irq_toggle(&priv->lmask, d, 0);
}
#ifdef CONFIG_SMP
static int plic_set_affinity(struct irq_data *d,
const struct cpumask *mask_val, bool force)
{
unsigned int cpu;
struct cpumask amask;
struct plic_priv *priv = irq_get_chip_data(d->irq);
cpumask_and(&amask, &priv->lmask, mask_val);
if (force)
cpu = cpumask_first(&amask);
else
cpu = cpumask_any_and(&amask, cpu_online_mask);
if (cpu >= nr_cpu_ids)
return -EINVAL;
plic_irq_toggle(&priv->lmask, d, 0);
plic_irq_toggle(cpumask_of(cpu), d, 1);
irq_data_update_effective_affinity(d, cpumask_of(cpu));
return IRQ_SET_MASK_OK_DONE;
}
#endif
static void plic_irq_eoi(struct irq_data *d)
{
struct plic_handler *handler = this_cpu_ptr(&plic_handlers);
writel(d->hwirq, handler->hart_base + CONTEXT_CLAIM);
}
static struct irq_chip plic_chip = {
.name = "SiFive PLIC",
.irq_mask = plic_irq_mask,
.irq_unmask = plic_irq_unmask,
.irq_eoi = plic_irq_eoi,
#ifdef CONFIG_SMP
.irq_set_affinity = plic_set_affinity,
#endif
};
static int plic_irqdomain_map(struct irq_domain *d, unsigned int irq,
irq_hw_number_t hwirq)
{
irq_domain_set_info(d, irq, hwirq, &plic_chip, d->host_data,
handle_fasteoi_irq, NULL, NULL);
irq_set_noprobe(irq);
return 0;
}
static int plic_irq_domain_alloc(struct irq_domain *domain, unsigned int virq,
unsigned int nr_irqs, void *arg)
{
int i, ret;
irq_hw_number_t hwirq;
unsigned int type;
struct irq_fwspec *fwspec = arg;
ret = irq_domain_translate_onecell(domain, fwspec, &hwirq, &type);
if (ret)
return ret;
for (i = 0; i < nr_irqs; i++) {
ret = plic_irqdomain_map(domain, virq + i, hwirq + i);
if (ret)
return ret;
}
return 0;
}
static const struct irq_domain_ops plic_irqdomain_ops = {
.translate = irq_domain_translate_onecell,
.alloc = plic_irq_domain_alloc,
.free = irq_domain_free_irqs_top,
};
/*
* Handling an interrupt is a two-step process: first you claim the interrupt
* by reading the claim register, then you complete the interrupt by writing
* that source ID back to the same claim register. This automatically enables
* and disables the interrupt, so there's nothing else to do.
*/
static void plic_handle_irq(struct pt_regs *regs)
{
struct plic_handler *handler = this_cpu_ptr(&plic_handlers);
void __iomem *claim = handler->hart_base + CONTEXT_CLAIM;
irq_hw_number_t hwirq;
WARN_ON_ONCE(!handler->present);
csr_clear(CSR_IE, IE_EIE);
while ((hwirq = readl(claim))) {
int irq = irq_find_mapping(handler->priv->irqdomain, hwirq);
if (unlikely(irq <= 0))
pr_warn_ratelimited("can't find mapping for hwirq %lu\n",
hwirq);
else
generic_handle_irq(irq);
}
csr_set(CSR_IE, IE_EIE);
}
/*
* Walk up the DT tree until we find an active RISC-V core (HART) node and
* extract the cpuid from it.
*/
static int plic_find_hart_id(struct device_node *node)
{
for (; node; node = node->parent) {
if (of_device_is_compatible(node, "riscv"))
return riscv_of_processor_hartid(node);
}
return -1;
}
static void plic_set_threshold(struct plic_handler *handler, u32 threshold)
{
/* priority must be > threshold to trigger an interrupt */
writel(threshold, handler->hart_base + CONTEXT_THRESHOLD);
}
static int plic_dying_cpu(unsigned int cpu)
{
struct plic_handler *handler = this_cpu_ptr(&plic_handlers);
csr_clear(CSR_IE, IE_EIE);
plic_set_threshold(handler, PLIC_DISABLE_THRESHOLD);
return 0;
}
static int plic_starting_cpu(unsigned int cpu)
{
struct plic_handler *handler = this_cpu_ptr(&plic_handlers);
csr_set(CSR_IE, IE_EIE);
plic_set_threshold(handler, PLIC_ENABLE_THRESHOLD);
return 0;
}
static int __init plic_init(struct device_node *node,
struct device_node *parent)
{
int error = 0, nr_contexts, nr_handlers = 0, i;
u32 nr_irqs;
struct plic_priv *priv;
priv = kzalloc(sizeof(*priv), GFP_KERNEL);
if (!priv)
return -ENOMEM;
priv->regs = of_iomap(node, 0);
if (WARN_ON(!priv->regs)) {
error = -EIO;
goto out_free_priv;
}
error = -EINVAL;
of_property_read_u32(node, "riscv,ndev", &nr_irqs);
if (WARN_ON(!nr_irqs))
goto out_iounmap;
nr_contexts = of_irq_count(node);
if (WARN_ON(!nr_contexts))
goto out_iounmap;
if (WARN_ON(nr_contexts < num_possible_cpus()))
goto out_iounmap;
error = -ENOMEM;
priv->irqdomain = irq_domain_add_linear(node, nr_irqs + 1,
&plic_irqdomain_ops, priv);
if (WARN_ON(!priv->irqdomain))
goto out_iounmap;
for (i = 0; i < nr_contexts; i++) {
struct of_phandle_args parent;
struct plic_handler *handler;
irq_hw_number_t hwirq;
int cpu, hartid;
if (of_irq_parse_one(node, i, &parent)) {
pr_err("failed to parse parent for context %d.\n", i);
continue;
}
/*
* Skip contexts other than external interrupts for our
* privilege level.
*/
if (parent.args[0] != RV_IRQ_EXT)
continue;
hartid = plic_find_hart_id(parent.np);
if (hartid < 0) {
pr_warn("failed to parse hart ID for context %d.\n", i);
continue;
}
cpu = riscv_hartid_to_cpuid(hartid);
if (cpu < 0) {
pr_warn("Invalid cpuid for context %d\n", i);
continue;
}
/*
* When running in M-mode we need to ignore the S-mode handler.
* Here we assume it always comes later, but that might be a
* little fragile.
*/
handler = per_cpu_ptr(&plic_handlers, cpu);
if (handler->present) {
pr_warn("handler already present for context %d.\n", i);
plic_set_threshold(handler, PLIC_DISABLE_THRESHOLD);
goto done;
}
cpumask_set_cpu(cpu, &priv->lmask);
handler->present = true;
handler->hart_base =
priv->regs + CONTEXT_BASE + i * CONTEXT_PER_HART;
raw_spin_lock_init(&handler->enable_lock);
handler->enable_base =
priv->regs + ENABLE_BASE + i * ENABLE_PER_HART;
handler->priv = priv;
done:
for (hwirq = 1; hwirq <= nr_irqs; hwirq++)
plic_toggle(handler, hwirq, 0);
nr_handlers++;
}
cpuhp_setup_state(CPUHP_AP_IRQ_SIFIVE_PLIC_STARTING,
"irqchip/sifive/plic:starting",
plic_starting_cpu, plic_dying_cpu);
pr_info("mapped %d interrupts with %d handlers for %d contexts.\n",
nr_irqs, nr_handlers, nr_contexts);
set_handle_irq(plic_handle_irq);
return 0;
out_iounmap:
iounmap(priv->regs);
out_free_priv:
kfree(priv);
return error;
}
IRQCHIP_DECLARE(sifive_plic, "sifive,plic-1.0.0", plic_init);
IRQCHIP_DECLARE(riscv_plic0, "riscv,plic0", plic_init); /* for legacy systems */