diff options
Diffstat (limited to 'drivers/irqchip/irq-ompic.c')
| -rw-r--r-- | drivers/irqchip/irq-ompic.c | 202 |
1 files changed, 202 insertions, 0 deletions
diff --git a/drivers/irqchip/irq-ompic.c b/drivers/irqchip/irq-ompic.c new file mode 100644 index 000000000..e66ef4373 --- /dev/null +++ b/drivers/irqchip/irq-ompic.c @@ -0,0 +1,202 @@ +/* + * Open Multi-Processor Interrupt Controller driver + * + * Copyright (C) 2014 Stefan Kristiansson <stefan.kristiansson@saunalahti.fi> + * Copyright (C) 2017 Stafford Horne <shorne@gmail.com> + * + * This file is licensed under the terms of the GNU General Public License + * version 2. This program is licensed "as is" without any warranty of any + * kind, whether express or implied. + * + * The ompic device handles IPI communication between cores in multi-core + * OpenRISC systems. + * + * Registers + * + * For each CPU the ompic has 2 registers. The control register for sending + * and acking IPIs and the status register for receiving IPIs. The register + * layouts are as follows: + * + * Control register + * +---------+---------+----------+---------+ + * | 31 | 30 | 29 .. 16 | 15 .. 0 | + * ----------+---------+----------+---------- + * | IRQ ACK | IRQ GEN | DST CORE | DATA | + * +---------+---------+----------+---------+ + * + * Status register + * +----------+-------------+----------+---------+ + * | 31 | 30 | 29 .. 16 | 15 .. 0 | + * -----------+-------------+----------+---------+ + * | Reserved | IRQ Pending | SRC CORE | DATA | + * +----------+-------------+----------+---------+ + * + * Architecture + * + * - The ompic generates a level interrupt to the CPU PIC when a message is + * ready. Messages are delivered via the memory bus. + * - The ompic does not have any interrupt input lines. + * - The ompic is wired to the same irq line on each core. + * - Devices are wired to the same irq line on each core. + * + * +---------+ +---------+ + * | CPU | | CPU | + * | Core 0 |<==\ (memory access) /==>| Core 1 | + * | [ PIC ]| | | | [ PIC ]| + * +----^-^--+ | | +----^-^--+ + * | | v v | | + * <====|=|=================================|=|==> (memory bus) + * | | ^ ^ | | + * (ipi | +------|---------+--------|-------|-+ (device irq) + * irq | | | | | + * core0)| +------|---------|--------|-------+ (ipi irq core1) + * | | | | | + * +----o-o-+ | +--------+ | + * | ompic |<===/ | Device |<===/ + * | IPI | +--------+ + * +--------+* + * + */ + +#include <linux/io.h> +#include <linux/ioport.h> +#include <linux/interrupt.h> +#include <linux/smp.h> +#include <linux/of.h> +#include <linux/of_irq.h> +#include <linux/of_address.h> + +#include <linux/irqchip.h> + +#define OMPIC_CPUBYTES 8 +#define OMPIC_CTRL(cpu) (0x0 + (cpu * OMPIC_CPUBYTES)) +#define OMPIC_STAT(cpu) (0x4 + (cpu * OMPIC_CPUBYTES)) + +#define OMPIC_CTRL_IRQ_ACK (1 << 31) +#define OMPIC_CTRL_IRQ_GEN (1 << 30) +#define OMPIC_CTRL_DST(cpu) (((cpu) & 0x3fff) << 16) + +#define OMPIC_STAT_IRQ_PENDING (1 << 30) + +#define OMPIC_DATA(x) ((x) & 0xffff) + +DEFINE_PER_CPU(unsigned long, ops); + +static void __iomem *ompic_base; + +static inline u32 ompic_readreg(void __iomem *base, loff_t offset) +{ + return ioread32be(base + offset); +} + +static void ompic_writereg(void __iomem *base, loff_t offset, u32 data) +{ + iowrite32be(data, base + offset); +} + +static void ompic_raise_softirq(const struct cpumask *mask, + unsigned int ipi_msg) +{ + unsigned int dst_cpu; + unsigned int src_cpu = smp_processor_id(); + + for_each_cpu(dst_cpu, mask) { + set_bit(ipi_msg, &per_cpu(ops, dst_cpu)); + + /* + * On OpenRISC the atomic set_bit() call implies a memory + * barrier. Otherwise we would need: smp_wmb(); paired + * with the read in ompic_ipi_handler. + */ + + ompic_writereg(ompic_base, OMPIC_CTRL(src_cpu), + OMPIC_CTRL_IRQ_GEN | + OMPIC_CTRL_DST(dst_cpu) | + OMPIC_DATA(1)); + } +} + +static irqreturn_t ompic_ipi_handler(int irq, void *dev_id) +{ + unsigned int cpu = smp_processor_id(); + unsigned long *pending_ops = &per_cpu(ops, cpu); + unsigned long ops; + + ompic_writereg(ompic_base, OMPIC_CTRL(cpu), OMPIC_CTRL_IRQ_ACK); + while ((ops = xchg(pending_ops, 0)) != 0) { + + /* + * On OpenRISC the atomic xchg() call implies a memory + * barrier. Otherwise we may need an smp_rmb(); paired + * with the write in ompic_raise_softirq. + */ + + do { + unsigned long ipi_msg; + + ipi_msg = __ffs(ops); + ops &= ~(1UL << ipi_msg); + + handle_IPI(ipi_msg); + } while (ops); + } + + return IRQ_HANDLED; +} + +static int __init ompic_of_init(struct device_node *node, + struct device_node *parent) +{ + struct resource res; + int irq; + int ret; + + /* Validate the DT */ + if (ompic_base) { + pr_err("ompic: duplicate ompic's are not supported"); + return -EEXIST; + } + + if (of_address_to_resource(node, 0, &res)) { + pr_err("ompic: reg property requires an address and size"); + return -EINVAL; + } + + if (resource_size(&res) < (num_possible_cpus() * OMPIC_CPUBYTES)) { + pr_err("ompic: reg size, currently %d must be at least %d", + resource_size(&res), + (num_possible_cpus() * OMPIC_CPUBYTES)); + return -EINVAL; + } + + /* Setup the device */ + ompic_base = ioremap(res.start, resource_size(&res)); + if (!ompic_base) { + pr_err("ompic: unable to map registers"); + return -ENOMEM; + } + + irq = irq_of_parse_and_map(node, 0); + if (irq <= 0) { + pr_err("ompic: unable to parse device irq"); + ret = -EINVAL; + goto out_unmap; + } + + ret = request_irq(irq, ompic_ipi_handler, IRQF_PERCPU, + "ompic_ipi", NULL); + if (ret) + goto out_irq_disp; + + set_smp_cross_call(ompic_raise_softirq); + + return 0; + +out_irq_disp: + irq_dispose_mapping(irq); +out_unmap: + iounmap(ompic_base); + ompic_base = NULL; + return ret; +} +IRQCHIP_DECLARE(ompic, "openrisc,ompic", ompic_of_init); |